BOREAS AFM-01 NOAA/ATDD Long-EZ Aircraft Flux Data over the SSA Summary This data set contains measurements from the NOAA/ATDD Long-EZ Aircraft collected during the 1994 IFCs at the SSA. These measurements were made from various instruments mounted on the aircraft. The data that were collected include: aircraft altitude, wind direction, wind speed, air temperature, potential temperature, water mixing ratio, U and V components of wind velocity, static pressure, surface radiative temperature, downwelling and upwelling total radiation, downwelling and upwelling longwave radiation, net radiation, downwelling and upwelling PAR, greenness index, CO2 concentration, O3 concentration, and CH4 concentration. There are also various columns that indicate the standard deviation, skewness, kurtosis, and trend of some of these data. The data are stored in tabular ASCII files. Table of Contents * 1 Data Set Overview * 2 Investigator(s) * 3 Theory of Measurements * 4 Equipment * 5 Data Acquisition Methods * 6 Observations * 7 Data Description * 8 Data Organization * 9 Data Manipulations * 10 Errors * 11 Notes * 12 Application of the Data Set * 13 Future Modifications and Plans * 14 Software * 15 Data Access * 16 Output Products and Availability * 17 References * 18 Glossary of Terms * 19 List of Acronyms * 20 Document Information 1. Data Set Overview 1.1 Data Set Identification BOREAS AFM-01 NOAA/ATDD Long-EZ Aircraft Flux Data over the SSA 1.2 Data Set Introduction This data set contains measurements from the National Oceanic and Atmospheric Administration (NOAA) Atmospheric Turbulence and Diffusion Division (ATDD) Long- EZ Aircraft collected during the 1994 Intensive Field Campaigns (IFCs) at the BOReal Ecosystem-Atmosphere Study (BOREAS) Southern Study Area (SSA). These measurements were made from various instruments mounted on the aircraft. The data that were collected include: aircraft altitude, wind direction, wind speed, air temperature, potential temperature, water mixing ratio, U and V components of wind velocity, static pressure, surface radiative temperature, downwelling and upwelling total radiation, downwelling and upwelling longwave radiation, net radiation, downwelling and upwelling photosynthetically active radiation (PAR), greenness index, CO2 concentration, O3 concentration, and CH4 concentration. There are also various columns that indicate the standard deviation, skewness, kurtosis, and trend of some of these data. The data are stored in tabular American Standard Code for Information Interchange (ASCII) files. 1.3 Objective/Purpose The primary objective was to measure the vertical flux density of sensible and latent heat, CO2, ozone, and momentum for extrapolating surface-based measurements to regional scales. An ultimate objective is to develop algorithms to relate boundary-layer processes to satellite-derived data. The AFM-01 team measured water vapor, sensible heat, CO2, and O3 air-surface exchange from the boreal forest to study the factors that control spatial variability of the exchange. Scalar flux densities were measured with ATDD's Long-EZ flux aircraft. The purpose of its flights was to observe energy, momentum, carbon, and ozone air-surface exchange with a 3-km resolution. Additionally, supporting meteorological parameters such as temperature, humidity, CO2 and O3 concentration, wind speed and direction, surface temperature, and incoming and net radiation were observed. All data were tagged with accurate time, position, and altitude. It is expected that these data will also be used to relate surface exchange to radiometric data available from satellites, i.e., validation of satellite data. Through this research, it is hoped that techniques can be developed to more accurately model air/surface exchange and to use satellite data for global monitoring of landscape health and climate change. 1.4 Summary of Parameters The following parameters have been submitted to the BOREAS Information System (BORIS) data base: temperature, dewpoint temperature, pressure, incoming and outgoing PAR, net radiation, wind velocity, H2O mixing ratio, CO2 mixing ratio, ozone mixing ratio, sensible heat flux, latent heat flux, momentum flux, CO2 flux, O3 flux, aircraft position, altitude (radar and pressure), and surface temperature. Profile parameters are not available at this date. 1.5 Discussion NOAA operated the Long-EZ in the one 1993 IFC and in all three 1994 IFCs. However, only the 1994 data are included in this data set. The main purpose of Long-EZ flights was to observe energy, momentum, ozone, and carbon dioxide air- surface exchange. The Long-EZ's strength is its ability to observe spatial variability in surface exchange with a 3-km resolution. This is accomplished by flying low (at 10 to 15 m above the surface) and slow (50 m/s) while making high frequency eddy flux measurements. Due to the short sampling time of 60 s, the flux variance in the reported 3-km segments is large. However, each 3-km segment is an unbiased estimate of the mean, and variance can be reduced by transects' superposition. Ideally, six repeated transects should be superimposed. This is usually possible since a key element of the Long-EZ flight plans is repeated observations. The data were collected during straight and level flux runs over the BOREAS site and in various project areas. A variety of flight strategies is reported (the Candle Lake transect, asterisks, grids, "L" patterns, soundings, etc.), from those described in the BOREAS experimental plan. The archive data include segment-averaged data, focusing on the fluxes, and the supporting meteorological, radiometric and aircraft positional data. No attempt will be made to archive the high rate (40 Hz) "raw" or processed output data (POD), which can be acquired from ATDD by special request. The references give a complete description of the Long-EZ and its instrument systems. The following table gives a quick overview of flight operations. BOREAS 1993-1994 NOAA Long-EZ Flight Operations Summary ITEM IFC 93 IFC 1 IFC 2 IFC 3 TOTAL ---- ----- ----- ----- ----- ----- Flight Hours 46 83 75 68 272 OJP Passes 84 98 33 71 296 OA Passes -- 44 47 23 114 OBS Passes -- 37 -- 32 69 Candle Lake 15 35 55 32 137 Grid Pattern -- -- 5 3 8 "L" Pattern -- 6 14 -- 20 Calibrations -- 28 5 2 35 Intercomparisons -- 18 8 2 28 NOTES: 1. Summary excludes experimental sampling patterns and miscellaneous sites. 2. Flight hours include all flight operations except ferry to and from Tennessee. 3. A pass is any flux tower crossing. Site-specific patterns such as "asterisk", 8's, and button holes were centered on the flux towers. 1.6 Related Data Sets BOREAS AFM-02 King Air 1994 Aircraft Flux and Moving Window Data BOREAS AFM-02 Aircraft Sounding Data BOREAS AFM-03 Aircraft Flux and Moving Window Data BOREAS AFM-03 Aircraft Sounding Data BOREAS AFM-04 Aircraft Flux Data BOREAS AFM-04 Aircraft Sounding Data 2. Investigator(s) 2.1 Investigator(s) Name and Title Timothy L. Crawford and Dennis Baldocchi Atmospheric Turbulence and Diffusion Laboratory NOAA Oak Ridge, TN (865) 576-0452 (865) 576-1327 (fax) T29@ornl.gov 2.2 Title of Investigation AFM-01: Experimental and Modeling Studies of Water Vapor, Heat and CO2 Exchange over a BOREAL Forest 2.3 Contact Information Contact 1 ------------ Laureen Gunter/Ed Dumas Atmospheric Turbulence and Diffusion Laboratory NOAA Oak Ridge, TN (865) 576-1246 (865) 576-3500 (865) 576-1327 (fax) Contact 2 ------------ David Knapp NASA/GSFC Greenbelt, MD (301) 286-1424 (301) 286-0239 (fax) David.Knapp@gsfc.nasa.gov 3. Theory of Measurements Air-surface exchange, or the surface flux, is a fundamental boundary condition controlling the atmospheric mass, momentum, and energy budgets. The species exchanged at the surface passes through the near surface boundary layer by turbulent transport. Thus, the surface exchange may be determined by measuring the near-surface turbulent or "eddy" flux. The eddy flux measurement is simple in concept, mathematically expressed as the covariance F = <(rw)'s'> 3.1 Here (rw)' is the turbulent fluctuation of the product of the dry air density and vertical velocity (i.e., dry air mass flux density), and s' is the turbulent fluctuation in the mixing ratio, relative to dry air, of the species of interest. The angle brackets indicate the appropriate ensemble average. This method has a first-principles basis, and a direct noninvasive nature. Since the near-surface flux is directly observed, the only assumption is that the flux divergence or gradient between the measurement and the surface is small. This assumption is valid when the mean transport, sources, and storage terms within the conservation equation are small. The reliability of this assumption weakens with increasing measurement altitude, and/or increasingly complex atmospheric and site conditions. The measurement principles for wind velocity and species concentration are well developed. Since the flux measurement is made above the surface without disturbing the surface, it cannot influence the exchange observed. Tower observations using a 15-min time scale, and airborne observations using a 3-km space scale, give data with sufficiently small time/space scale to permit the process studies needed to improve predictive capabilities. In the last 10 years, the accuracy of this technique has improved because of significant advancements in instrumentation and processing techniques. However, the details associated with proper instrument operation, data processing, and data interpretations are complex. This is especially true for airborne flux systems. For aircraft, both the instrument systems and data processing programs are more complex when compared to tower systems. For example, to determine wind velocity on an aircraft, the air velocity relative to the sensors is added to the sensor velocity relative to Earth. Both vectors are large and nearly cancel each other out (i.e., similar magnitude, opposite signs). Neither vector can be directly observed, but must be synthesized from many sensors. The synthesis process is intolerant to phase or amplitude errors introduced by sensors, data systems, or processing algorithms. Eddy Flux Measurement Theory The eddy flux method allows the short-term measurement of flux densities (vertical transport of mass, momentum, and energy per unit area and time). The measurement becomes especially powerful, but often difficult to interpret, when made from an aircraft. Aircraft turbulence data derive their power from information density per unit time, and the spatial freedom of the measurement platform. Both require greater effort in an analysis. Further, interpretation of aircraft data becomes more difficult whenever the data set also contains spatial trends and inhomogeneities. Mass conservation provides the basic framework for correct interpretation. Conservation of a conservative species, s, requires that the time rate of change of s within a control volume be balanced by the mean and turbulent flux through the volume's boundaries. From the Long-EZ, fluxes are measured usually around 15 m above the surface (higher from other aircraft and lower from towers). The flux measurement accurately defines the flux occurring at the flight altitude and along the flight track. However, most are interested in the surface flux. The flux observed at a flight altitude represents the surface flux if the following conditions are met. 1) The flight altitude is low enough to be within the constant flux layer. Above this, flux divergence becomes increasingly important with increasing altitudes, which makes the observed flux no longer representative of the surface flux. Such flux divergence usually causes an underestimate of the surface flux, but not always. Typically, mitigating concerns about flux divergence requires measurement within the lowest 10% of the turbulent boundary layer. With the exception of stable night boundary layers, the Long-EZ's 15 m sampling altitude satisfies this condition. However, the importance of storage and transport terms below the flight altitude should be considered. In unusual situations such as front passages, strong temperature, or species advection, such terms can still become significant. 2) The underlying surface is homogeneous. It should extend upwind of the flight track for about 100 times the sampling altitude. Also, it should extend along the flight track for a distance equivalent to the space average being applied in data processing. This ensures the development of an equilibrium surface boundary layer and adequate sampling time before conditions change. Airplane measurements remain valid whether or not these conditions are met. However, small-scale inhomogeneity greatly increases the difficulty of specifying and interpreting the mean state from which the turbulence departs and introduces samples from multiple populations into the measurement set. This difficulty increases as the contrast between inhomogeneous regions increases. 3) Stationary meteorological conditions should prevail during sampling. Such conditions as frontal passage and nightfall clearly violate this, featuring important contributions from the horizontal transport or storage terms, explicitly rejected by Eq. 3.1. However, less abrupt change can also be important. For example, if the air is warming 3 deg/hr, the heat flux at 15 m (Long-EZ flight level) will be 20 W/m2 less than at the surface due to storage. 4) Below the measurement height, s must be a conservative property. Fast chemical reactions involving s invalidate this assumption. For example, ozone reacts rapidly with NO. If there is a significant NO emission below the sampling altitude (soil flux or automobile emissions), it could easily lead to an incorrect interpretation of the observed flux. Eddy Flux Technique A significant part of the complexity of this measurement lies in separating turbulent fluctuation from mean, and defining an appropriate ensemble average. Equation 3.1 is not computationally useful until the turbulent fluctuations are defined. Traditionally, the fluctuations are defined as s = s' + S 3.2 where S is the appropriate ensemble mean of s. Given this definition, Eq. 3.1 may be rewritten as F = <[(rw) - (RW)](s -S)> = <(rw)s-(RW)S> 3.3 Here (RW) is not the product of the mean of the dry air density and the mean vertical velocity but the mean of their product. For heat flux, s =Cp*T where Cp is the moist air specific heat at constant pressure. Cp depends locally (i.e., at 40 Hz) on water vapor concentration. T is the potential temperature. The use of potential temperature compensates for the compressible nature of the atmosphere. Since there is a correlation between w and the aircraft altitude, the use of potential temperature is necessary to eliminate this false (rw)t correlation. For latent heat flux, s = Lq where L is the local temperature- dependent evaporation energy for water and q is the water vapor mixing ratio relative to dry air. For CO2, s becomes the CO2 mixing ratio relative to the dry air component. This approach satisfies the constraint outlined by Webb et.al. (1980) (no flux of dry air), and implicitly corrects all fluxes for heat and water vapor transport. On a tower, the mean is a time average. The fluctuation is then obtained as s' = s - S where S is the average over periods of around 15 to 30 min. However, s observed from an airplane contains both space- and time-related trends. In aircraft flux data, a space trend should also be considered. This is a tedious and difficult correction that requires much investigator interpretation. Only time trends have been removed for data submitted to BORIS. Eddies in a wide range of scales contribute to turbulent transfer. Successful eddy flux measurement requires proper sampling over this spectrum. The eddy size is expressed by a dimensionless frequency, nz/u, where n is the eddy size as a frequency, z the sampling height, and u the eddy transport speed past the sensor. The important eddy size ranges contributing to turbulent transfer are typically within 0.005 < nz/u < 5. For the Long-EZ, u = 50 m/s and z = 10 m. Therefore, from the Long-EZ, eddy sizes between 1.25 m and 1,250 m are important. Over deciduous forest during typical daytime turbulent conditions, little flux contribution occurs outside this range (Anderson et al. (1986)). However, due to the greater roughness of the BOREAS site, we suspect the important eddy flux range may be driven to longer wavelengths. The nz/u scaling points out the need for and advantage of fast-response turbulent measuring systems. Fast-response sensors/data systems combined with low-altitude flying allow the contributing eddies to be sampled in a shorter time and enhance the spatial resolution of the flux observation. The significant heterogeneity of the BOREAS experimental site makes it difficult quantitatively to specify the important eddy-size range contributing to turbulent transfer. Traditional spectral analysis is not appropriate due to strong site heterogeneity. To address this issue, two Candle Lake transects were processed with various covariance time scales or wavelength. The average flux along the transect normalized by the largest covariance result is presented in the following table. As the table shows, little flux is lost even at 20 s; therefore, our 60 s choice for BORIS submission is conservative. Normalized Covariance (%) vs. Wavelength(s) Wavelength U* H LE FluxCO2 5 s (250 m) 0.05 0.7 0.7 0.8 10 s (500 m) 0.69 0.9 0.8 0.9 20 s (1000 m) 0.39 0.9 0.9 0.9 30 s (1500 m) 0.24 0.9 0.9 0.9 40 s (2000 m) 0.16 0.9 0.9 0.9 60 s (3000 m) 0.10 0.9 0.9 0.9 80 s (4000 m) 0.01 1.0 0.9 0.9 100 s (5000 m) 0.03 0.9 1.0 1.0 110 s (5500 m) 0.00 0.9 0.9 0.9 Evaluating the accuracy of the eddy correlation method is not straightforward. Factors contributing to uncertainties are instrument errors, sensor time response, signal-to-noise ratio, sensor separation distance, height of the measurement, signal attenuation due to path averaging, and corruption through tubing. Natural variability, due to nonsteady conditions, turbulence intermittency, and surface inhomogeneities, can add additional uncertainty. Under ideal meteorological and site conditions, natural variability is around ±10%. Therefore, systems should be designed with an error less than this. However, the biggest problems with aircraft data are not related to data accuracy, but to data interpretations. Aircraft data implicitly represent a space average. The spatial variance is usually larger than 10%. 4. Equipment 4.1 Sensor/Instrument Description The equipment used for the airborne flux measurement includes ATDD's Long-EZ flux research aircraft, the airborne flux instrumentation, and ATDD's data reduction hardware with software. These three systems were specifically designed and manufactured by ATDD staff to ensure high-fidelity flux observations. The optimum use of this airborne system is boundary layer flux measurement. Long-EZ Description The Long-EZ flux research aircraft, N3R, is well suited and is specifically instrumented for high-fidelity, air-surface-exchange research (Crawford et al., 1996). The wide-body Long-EZ is an experimental aircraft built by Timothy L. Crawford. It is a larger, higher-powered and more capable version of the Rutan Long-EZ, a two-passenger, high-performance canard airplane. The aerodynamic characteristics of the Long-EZ are well suited for high-fidelity turbulent flux measurement. The pusher configuration leaves the front of the airframe free of propeller-induced disturbance, engine vibration, and exhaust. The small, laminar-flow airframe has an equivalent flat plate drag area of 0.2 m2. As a result, the nose region has small flow disturbance and is ideal for high- fidelity measurements of winds, temperature, and trace species. The canard design cannot stall and has superior pitch stability in turbulent conditions. This, combined with its low wing loading, allows for safe low-speed (50 m/s), low-altitude (10 m) flux measurement. For enhanced safety, the Long-EZ is equipped with a ballistically deployed safety parachute (deployment requires 0.9 s). The Long-EZ has an empty weight of 430 kg and a maximum gross takeoff weight of 800 kg. The aircraft service ceiling of 9,000 m must be reduced to 5,500 m because of oxygen system limitations. Endurance significantly exceeds 10 hours and a 2,000-nm range; however, pilot fatigue precludes routine 10-hour missions. More typical operations are two 4-hr or three 3-hr missions. Although small size (low flow distortion) is important to high-quality turbulence measurements, it is also a disadvantage. The small size combined with the current instrumentation leaves little room for additional instruments. Airborne Flux Instrumentation Description Wind velocity and virtual temperature fluctuations were measured with ATDD's turbulence probe (Crawford et al., 1992). The probe is mounted five chord lengths ahead of the wings, where flow disturbance is small. It carries pressure, temperature, and acceleration sensors in a nine-hole pressure-sphere gust probe of ATDD design. This sensor suite is specifically designed to extend eddy flux measurement at the higher frequencies required for low altitude flight. A thermistor in the central pressure port provides simultaneous temperature measurement, at a location symmetrical with respect to the flow, for accurate determination of true air speed and heat flux. CO2 and water vapor fluctuations were measured with an open-path, infrared gas absorption (IRGA) analyzer, developed at ATDD (Auble and Meyers, 1992). This sensor responds to frequencies up to 40 Hz and has low noise and high sensitivity (for CO2, 20 mg/m3/v). The sensor is rugged and experiences little drift. A unique difference in the Long-EZ instrument system is its pioneering use of a differential Global Positioning System (GPS) for extremely accurate position, velocity, and platform attitude measurement. The airborne flux instrumentation and the data system with its associated software were specifically designed and built by ATDD (Crawford et al., 1991). This system connects to the pilot's digital interface, which controls instrument power distribution, two-way "smart" instrument communication, and the data- storage algorithm. The data stream is dominated by the high-frequency analog signals. Analog signals are first electronically conditioned by 30-Hz lowpass Butterworth anti-aliasing filters. The conditioned and voltage scaled signals are then digitized at 200 Hz. The 200-Hz data are digitally filtered and subsampled to 40 Hz. Although several other data frequencies are being written to disk, all are synchronized to a single clock frequency. Spectra and co- spectra data analysis show that the 40-Hz flux data rate is adequate for measuring fluxes above forest canopies at the Long-EZ flight speed and altitude. Data Reduction Hardware With Software The eddy flux densities are determined by calculating the covariance between vertical velocity and scalar fluctuations while correcting for aircraft speed variations (Crawford et al., 1993a). 4.1.1 Collection Environment Data were collected during IFCs 1, 2, and 3 under flight conditions outlined in the BOREAS Flight Plans for flux aircraft. 4.1.2 Source/Platform The platform used to collect this data was a Long-EZ aircraft built by Timothy Crawford. 4.1.3 Source/Platform Mission Objectives The mission objective was to collect CO2, O3, CH4 concentrations as well as other atmospheric and radiation parameters over various BOREAS sites. 4.1.4 Key Variables The data that were collected include: aircraft altitude, wind direction, wind speed, air temperature, potential temperature, water mixing ratio, U and V components of wind velocity, static pressure, surface radiative temperature, downwelling and upwelling total radiation, downwelling and upwelling longwave radiation, net radiation, downwelling and upwelling PAR, greenness index, CO2 concentration, O3 concentration, and CH4 concentration. There are also various columns that indicate the standard deviation, skewness, kurtosis, and trend of some of these data. 4.1.5 Principles of Operation None given. 4.1.6 Sensor/Instrument Measurement Geometry ATDD's turbulence and heat flux probe is mounted on the airplane at the end of a 1-m nose boom. This places the probe five wing chords in front of the canard and six wing chords in front of the main wing. All high-frequency motion (acceleration, pressure, and temperature) sensors are within the nine-hole pressure sphere. The center of the sphere is the origin of the computational coordinate system. A backup fast-response temperature sensor and slow-response temperature sensor for calibration reference are mounted on the nose of the airplane along with ATDD's fast-response IRGA H2O/CO2 analyzer. Forward on the left side of the nose is the net radiometer. The small airframe size results in very small solid angle interference from the airframe at the nose. Located at the aircraft center of gravity (CG) are the low-frequency reference sensors for H2O, CO2, and O3. The infrared surface temperature sensor, the chilled-mirror dewpoint hygrometer, and the fast-response O3 analyzer are also at this location. The infrared temperature sensor is nadir-mounted through the floor. With its 15-degree field of view, it "sees" a 5-m-wide footprint. There are six GPS antennae strategically placed around the airframe, which are connected to three separate GPS receivers. The critical system is a four-antennae differential GPS (DGPS) attitude system. Attitude is determined by differentially measuring the relative positions, within 1 cm, of nose, tail and wing antennae. The current GPS is limited to operation at 4 Hz. A system upgrade with associated software enhancements is expected to allow this system to operate at 10 Hz in the future. When the attitude system output is increased to 10 Hz, one of the redundant GPS position receivers and the three-axis gyro system at the CG can be eliminated. 4.1.7 Manufacturer of Sensor/Instrument The microprocessor revolution has accelerated technological advancements in instrumentation. The instrumentation on the Long-EZ has been upgraded continuously to keep pace with instrument technology. Improved instrumentation is installed as it becomes available or is found desirable. Typically, several instruments change each year. The following table lists the instruments, manufacturer, location, sampling rate, accuracy, resolution, and units of the instruments that were onboard during BOREAS IFCs. Variable Name Manufacture/Model Loc/Hz Acc/Res Unit ----------------------------------------------------------------------- Acceleration Ax Sundstrand/QA-700 P/40 25/10 m/s2 Acceleration Ay Sundstrand/QA-700 P/40 50/35 m/s2 Acceleration Az Sundstrand/QA-700 P/40 70/50 m/s2 Pressure Px SenSym/SCX01 P/40 70/0.6 mb Pressure Py SenSym/SCXL004 P/40 50/0.5 mb Pressure Pz SenSym/SCXL004 P/40 50/0.5 mb Dif Stc Pres DelP SenSym/SCXL004 P/40 50/0.5 mb Static Pres Setra/270 (mod) H/1 0.5/0.01 mb Attitude Pitch TANS VECTOR-Trimble C/1 0.08/-- deg Attitude Roll TANS VECTOR-Trimble C/1 0.08/-- deg Attitude Head TANS VECTOR-Trimble C/1 0.05/-- deg Position Lat DGPS P/1 3 / 3 deg Position Lng DGPS P/1 3 / 3 deg Fast temp Tp ATDD/u-bead thermistor P/40 0.1/0.005 C Mean temperature RPT/Hy-Cal BA-507-B P/1 0.05/0.03 C Dewpoint temp Td EG&G/ C/1 0.5/0.006 C Water vapor fast ATDD/IRGA H/40 ---/22 g/m3 Water vapor ref LI_COR/6262 C/1 1%/0.005 mM/M CO2 fast ATDD/IRGA H/40 ---/0.2 mg/m3 CO2 ref LI-COR/6262 C/1 <1/0.2 uM/M O3 fast ATDD/Chemiluminescence C/40 / ppb O3 ref Modified TECO / / ppb ----------------------------------------------------------------------- Notes: Sensor locations: P - in pressure sphere; H - on probe hatch mountcover; C - Aircraft CG 4.2 Calibration All instruments were calibrated before and after each IFC. Complex instruments (such as CO2 and O3) were calibrated daily. All instruments undergo a comprehensive pre- and post-flight check for correct operation. The first and last data file for each flight go through a quality assurance (QA) procedure prior to the next flight. As part of the QA, takeoff and landing meteorological data are checked against conditions observed at the airport. Additionally, all data undergo time-series display, statistical and spectral analysis, and preliminary data reduction as part of the QA procedure. 4.2.1 Specifications Not available. 4.2.1.1 Tolerance Not available. 4.2.2 Frequency of Calibration All instruments were calibrated before and after each IFC. Daily calibrations were performed on the CO2 and O3 instruments. 4.2.3 Other Calibration Information See Section 17 (References). 5. Data Acquisition Methods Data were collected during IFCs 1, 2, and 3 under flight conditions outlined in the BOREAS Flight Plans for flux aircraft. 6. Observations 6.1 Data Notes None. 6.2 Field Notes 25 May 1994 Flight hours 4.4 (Hobbs) Pilot: TLC SUMMARY: Today's flight consisted of low-level agriculture runs in the SSA with entry in the western corridor, combined with a site specific asterisk pattern over Tower 5 (Old Jack Pine). WEATHER: Mostly clear and sunny. TAKEOFF: 1744Z, FSS Temp = 7.9 C, Dew Pt = 6.6 C LANDING: 2045Z On ground met readings prior to flight: P = 969.1 mb, T = 25.9 C, Tw = 19.4 C NOTE: the on ground pre-flight T and Tw readings are probably wrong, due to a problem with the psychrometer. On ground met reading after the flight: P = 968.0 mb, T = 19.0 C, Tw = 13.7 C. After flight: 1515 local time, zeroing Li-COR. Li-COR calibration with U.Wyo gases: H2O: 0.45; CO2: -1.8, so zero is real close to where it should be. Current pot settings are 2.4 (CO2) and 5.0 (H2O). 26 May 19944.4 Flight Hours (Hobbs) Pilot: TLC SUMMARY: 2 profiles & 5 Candle lake runs at 20 m--very turbulent with strong wind. Note: The NCAR Electra flew the Candle Lake line during the same period from 100 m to above the boundary layer. WEATHER: Started clear with 15% Cu building by mid run, some high stratus TAKEOFF: 1550Z, FSS Temp 19.3 C; Dew Pt 7.0 Wind; 180/15 LANDING: 2000Z, FSS Temp 22.3 C; Dew Pt 6.1; Alt 29.84 On ground met readings prior to flight: T=20 C, Tw=16.9 C, P=963.4 mb After flight met readings: T=22.3 C, Tw=13.3 C, P=961.3 mb 26 May 1994 Flight hours 1.9 (Hobbs) Pilot: EJD SUMMARY: Flight plan was to fly a site specific, asterisk over the Old Aspen (OA) site in the SSA.*****NO GYROS FOR THE WHOLE FLIGHT***** WEATHER: Mostly sunny, some clouds around, windy TAKEOFF: 2030Z LANDING: 2220Z On ground met readings prior to flight: T=22.3 C, Tw=13.3 C, P=961.3 mb After flight met readings: T=22.5 C, Tw=12.7 C, P=960.2 mb Note: When processing data after the flight, it appears the gyros were OFF for the entire flight - not malfunctioning. Also, the ozone inlet came off sometime during the flight. 27 May 1994 4.3 Flight Hours (Hobbs) Pilot: TLC SUMMARY: Two site specific runs - asterisks over the Black Spruce Tower, then one over the Old Jack Pine tower. CO2 sensor was calibrated prior to flight. WEATHER: On Takeoff, clear wx conditions - haze to East no clouds directly above, thin high stratus. Basically clear all day, with stratus building and coming in from the west at about 2000Z - 50%, from morning of about 15%. Note: BS not a good place for a site specific - there is a lot of heterogeneity: lot of little lakes, lot of chopped up stuff - lot ofter rain - looking for the best direction that offers a good comparison with the tower. OJP coordinated from Piers 53.916N, 104.69W. TAKEOFF: 1630Z FSS Temp 22 C LANDING: 2030 On ground met readings prior to takeoff: T=21.6 C, Tw=15.2 C, P=954.7 mb After flight met readings: T=28 C, Tw=15.4 C, P=952.4 29 May 1994 Flight hours 2.8 (Hobbs) Pilot: TLC SUMMARY: An OJP site asterisk plan was flown. In conjunction, the Twin Otter was flying an "L" pattern across all tower sites, and the NASA helicopter took measurements in the same area. CO2 IRGA calibration was done prior to flight, so there is an updated zero and span available. Additionally, the probe temperature sensor was changed from the glass microbead to the wire microbead; therefore, the zero and span of the temperature probe has changed. WEATHER: Overcast most of the day. At P.A.: cloud est to be 3200 Sct, 9000Bkn, 25000 Bkn, vis 15 miles. It was cloudier to the southwest when over the site. At landing, a system had moved in from the south, and light precipitation had begun. TAKEOFF: 1740Z LANDING: 2020Z NOTE: The date and time were set incorrectly, so the first file has the wrong time. The GPS reset the time when the file was closed. he date had been 27 May, (edited after the flight). 31 May 1994 Flight hours 5.4 hours (Hobbs) Pilot: TLC SUMMARY: The flight plan consisted of an intercomparison with the Canadian TO to the grid where the TO was to sample. After that, the Long-EZ flew 7-Candle Lake runs. The NCAR Electra also flew the Candle Lake run. WEATHER: Clear in the morning, small cumulus by mid-morning, with increasing cloud cover by mid-afternoon. Maximum coverage 25% by the afternoon. Note: No ozone instruments installed (fast or slow). Repaired DelP sensor. "Hell-hole" access taped up, trying to reduce pressure in cabin to better ventilate the temperature probe. TAKEOFF: 1615Z FSS Temp = 16.6 C, Dew Pt = 7.1 C, winds 300/5, alt 30.11 LANDING: 2120Z 1 June 1994 Flight hours 5.1 hours (Hobbs) Pilot: TLC SUMMARY: Flight plan consisted of asterisks first over BS and OJP, then a Candle Lake run with the Twin Otter for intercomparison, followed by an asterisk over Old Aspen. WEATHER: Initially clear (0800L), then clouding over by mid-morning to noon. By landing, the sky was 90% coverage. Calibration of IRGA recorded to disk prior to flight - 3 concentrations: 301.5, 365.8, 415 ppm. Also, radar altimeter failed on the last few files of the prior flight. And, there are no Magellan or ozone instruments. TAKEOFF: 1445Z FSS Temp=18.2, Dew Pt = 7.6, alt 30.14, winds 120/10 LANDING: 2000Z 1 June 1994 Flight hours 2.6 (Hobbs) Pilot: EJD SUMMARY: Flight plan was an asterisk over the Old Aspen site, then a few low passes over the Black Spruce site (for the press). Tape recorder failed, so there are no in flight remarks. 2 June 1994 Flight hours 1.1 hours (Hobbs) Pilot: EJD SUMMARY: Purpose of flight was to do a pitch and wind cal at constant altitude, i.e., speed ups/downs, wind box, wind circle. WEATHER: Overcast, light precip. TAKEOFF: 1450Z LANDING: 1550Z FSS T = 17, Dew Pt = 8 4 June 1994 Flight hours 2.2 (Hobbs) Pilot: TLC SUMMARY: This was a calibration, wind box, wind circle, speed pitch up/dn flight. The radar altimeter is back up and working fine. The ozone instruments are still out. WEATHER: Calm, stable condition. The winds are very light and out of the NE. The haze from the paper plant was in the area, and some crud clouds were in the south. By landing, it was starting to clear out...minor windshift. TAKEOFF: 1200Z FSS Temp = 9.4, Dew pt = 9.2, alt 29.89, winds calm LANDING: 1400Z FSS Temp = 15., Dew pt = 12., alt 29.89, winds calm Notes on landing: looking at paper mill, the winds seem to be 210 deg at the surface, then about 230 deg aloft. 4 June 1994 Flight hours 4.5 (Hobbs) Pilot: TLC SUMMARY: Candle Lake runs coupled with an intercomparison with the Wyoming King Air. WEATHER: Clear, calm, and mostly sunny. Some cumulus forming. TAKEOFF: 1500Z FSS T = 16.8, Td = 11.9, winds calm, alt 29.89 LANDING 1930Z FSS T = 22.7, Td = 9.6 Notes: Magellan GPS not working all morning. The ozone instruments are out. 4 June 1994 Flight hours 2.8 (Hobbs) Pilot: EJD SUMMARY: Originally there was to be an asterisk to be done over OJP; however, it was precipitating over the site, so an asterisk was done over the Black Spruce site. WEATHER: By mid-afternoon, there was about 50% cloud cover, mixed types, mostly Cu. TAKEOFF: 2015Z LANDING: 2300Z FSS T=24, Td=10 Notes: Ozone instruments were re-installed for this flight. 6 June 1994 Flight hours 5.1 (Hobbs) Pilot: TLC SUMMARY: The "h", "i", "j" L-shaped pattern was flown today. The KA was going to be flying the same pattern, and the Electra was going to be in the same vicinity. In the 2nd portion, different altitudes were flown for flux divergence measurements. WEATHER: Some cloudiness in the early morning, coupled with ground fog progressing to approx. 50% coverage by mid-afternoon. TAKEOFF: FSS winds 050/10, alt 29.98, T = 14.1, Td = 11.9 Notes: During the first part of the flight, one of the switches on the gyros weren't on...after landing, the switch was turned on, ready for immediate takeoff. At approximately 1100, during flight, the alternator fuse blew, so Tim shutoff electrical power and came in. The fuse was replaced, and there was another takeoff at approximately 1215L. Same problem occurred, and the next landing was at approx. 1430L. Additionally, the ozone inlet tube came off sometime during flight, so the slow ozone data may be bad. 7 June 1994 Flight hours 4.3 (Hobbs) Pilot: TLC SUMMARY: Candle Lake runs - the only one of the BOREAS Airforce out there WEATHER: Windy, warm, blue skies with cirrus to the south. TAKEOFF: 1440Z FSS Alt 30.06, winds 090/15 LANDING: 1850Z Notes: Ozone inlet tube came off sometime during flight yesterday...repaired for today's flight. Before flight, glycol mixed with ethyl alcohol was added to the fast-response ozone instrument. During flight, TLC noted that the fast sensor #1 was over sensitive, but that fast sensor #2 seemed OK. Also prior to flight, there was a calibration done on the fast ozone with the new solution, and there was a calibration on the CO2instruments with the 3 concentrations. 7 June 1994 Flight hours 3.4 (Hobbs) Pilot: EJD SUMMARY: Candle Lake runs WEATHER: Very windy, clear, cirrus to the south. TAKEOFF: 2000Z Alt 30.02 FSS Winds 090/15G20 T=21. LANDING: 2330Z FSS T=22.6, TD=-1.0 Note: The fast ozone sensors ran out of solution sometime during flight. 8 June 1994 Flight hours 4.7 (Hobbs) Pilot: TLC SUMMARY: Asterisk pattern around Old Jack Pine - first counterclockwise in 15 deg increments, then counterclockwise in 15 deg increments. WEATHER: On site, initially clear with cirrus aloft, then gradual increasing cloudiness. Winds along the path were approx 10 m/s. TAKEOFF: 1530Z FSS T=15.5, Td=6.4, Alt 29.99, winds 120/10 LANDING: 1930Z FSS T=18.7, Td=11.3, winds 230/5 Notes: In-line filter installed on Li-COR 6262 this morning - trying to mitigate pollen problems. CO2 and ozone calibration done prior to flight, and in between flights. No TANS pseudo ranges during flight. 8 June 1994 Flight hours 2.5 (Hobbs) Pilot: EJD SUMMARY: OJP asterisks WEATHER: Overcast to the south, mostly clear to the north. TAKEOFF: 2015Z FSS T = 18.8 C, Td = 11.5 C, winds 190/10, Alt 29.97 LANDING: 2230Z FSS T = 18.4 C, Td = 10.2 C, winds 210/5, Alt 29.97 Notes: Solution on fast response ozone sensors ran out during flight. 10 June 1994 Flight hours 5.6 (Hobbs) Pilot: TLC SUMMARY: This flight was an asterisk over the Old Aspen site, and then 5 runs along the Candle Lake transect. WEATHER: Clear in the morning (0800 or so), some ground haze - then by mid- morning, there was alto-status mixed with cirrus and some small Cu. By mid- afternoon the wind increased, and the stratus and cirrus had dissipated, and small Cu covered about 25-30% of the sky. TAKEOFF: 1445Z FSS T = 17.3, Td = 7.9 (jumped to 8.3 while he was talking) winds 300/10, Alt 29.98 LANDING: 2030 FSS T = 22.4, Td = 8.1 Note: Adj offset on both the fast ozones. Also a CO2 cal done 10 June 1994 Flight hours 3.3 (Hobbs) Pilot: EJD SUMMARY: On this flight, a figure 8 pattern was flown over the Old Jack Pine site. WEATHER: Mostly clear - Cu hum. TAKEOFF: 2030Z FSS T = 22.2, Td = 7.8 LANDING: 2355Z FSS T = 23.3, Td = 5.9 Note: On landing, the program had an overflow error message. 11 June 1994 Flight hours 4.8 (Hobbs) Pilot: TLC SUMMARY: The h, i, j "L" pattern was flown, coupled with circles at various altitudes over Old Jack Pine. WEATHER: Cu building throughout the flight (10% coverage at the beginning, ending with about 40% coverage). Areas of light precip around the OJP site. TAKEOFF: 1610Z FSS T = 18.2, Td = 9.5, winds 300/5 LANDING: 2015Z FSS T = 20.8, Td = 9.4, winds 290/5 to 10 Notes: Original takeoff was at 0900L - TANS didn't come up, so TLC landed and reloaded vectors and rebooted the top board. 12 June 1994 Flight hours 1.0 (Hobbs) Pilot: EJD SUMMARY: Pitch cal WEATHER: 30-40% coverage of small Cu congestus TAKEOFF: 1230Z winds 290/5, Alt 29.68 T = 11.7, Td = 9.3 Landing: 1315Z T = 12.8, Td = 9.7 Notes: Weight = 1397.3 lbs; CG = 101.48 in. No ozone or CO2 for this flight. 12 June 1994 Flight hours 3.7 (Hobbs) Pilot: EJD SUMMARY: The original plan called for Figure 8s over OJP; however, there was bad weather in the area, so EJD landed and discussed an alternate plan. The decision was then to do the Old Aspen site. Figure 8s and 'Ls' were done over that site. WEATHER: Cu building - clouds and rain over the area - mixed bag of weather TAKEOFF: 1500Z (1st), 1615Z (2nd) FSS winds 330/5, Alt 29.68 LANDING: 1600Z(lst), 1845Z (2nd) FSS T=17.3, Td=8.6, winds 360/5G10, Alt 29.68 NOTE: ***Gyros were off for whole flight*** 12 June 1994 Flight hours 2.3 (Hobbs) Pilot: TLC SUMMARY: Figure eights over Old Jack Pine WEATHER: Building Cu throughout the flight..no precip for most of the time, some light precip near the end. TAKEOFF: 1915Z FSS T=17.2, Td=8.6 LANDING: 2100Z Notes: ± 2.5 nm around the tower has similar surface use as the tower -the rest is choppy and dissimilar (TLC in-flight note). Flight was terminated early because the data system 'crashed'. *****GYROS WERE OFF THE WHOLE FLIGHT***** 20 July 1994 Flight time 5.1 hr (Hobbs) Pilot: TLC SUMMARY: Pre-Test flight, 2 PRO's and 7 Candle Lake transects. Both the Electra and King Air flew the CL transects at the same time. Fast and slow O3 sensors installed after significant inprovements between IFC1-2. Now believed to be working. WEATHER: Lots of rain last few days. Forest fires have reduced visibility to about 5 miles. The wind is from the north @10 kts. At 1600 Cu started to build. During the day buildup continued at a slow but persistent rate to around 50% by the end of the flight. PROBLEM - Flux gate had compass failed, now removed. Some GPS ground station data lost around noon. The NET did not work this flight due to a bad connection which was repaired after the flight. File 07201834 had an unreadable block. On test flight the gyro 10A fuse blew. It was replaced with a 12A. Does this indicate a future problem? NOTE: Average site altitude is about 1900 msl. The gyro was cleaned before this flight to remove data "spikes". 21 July 1994 Flight time 5.1 hours (Hobbs) Pilot: EJD SUMMARY: 1 Pitch Cal, 7 Candle Lake transects, 1 Profile. Both the Twin Otter and King Air flew the grid transects at the same time. WEATHER: Excellent visibility today. No Cu in the morning, built to less than 10% in the afternoon. Wind calm initially, picked up considerably in the afternoon. Turbulence very light in the morning picked up considerably in the afternoon. PROBLEM - No problems noted during flight. All instruments seemed to work well. 21 July 1994 Flight time 3.8 hours (Hobbs) Pilot: TLC SUMMARY: 2-PRO's, 2 complete and 2 short Candle Lake transects. The last CL transect was flown with the TO. Flight direction was to west. At Candle lake, the flight speed was reduced from 120 kts to 110 kts. FE also flew the transect but ahead of FL & FT. This was a "golden day" with 16 flights! WEATHER: Clear sky all day! Winds low and from 030 PROBLEM - Data system crashed caused early mission termination. NOTE: Since the winds are down the transect and lots of flight missions were flown, this may be a good day for "lake effects" boundary layer research. 22 July 1994 Flight time 1.7 hours (Hobbs) Pilot: EJD SUMMARY: 2 Pitch Cals, 1 Candle Lake transect. Late evening, not much activity. WEATHER: Clear over YPA, high clouds over CL transect. Very little turbulence on CL run. PROBLEM - No problems noted during flight. All instruments seemed to work well. 23 July 1994 Flight time 4.7 hours (Hobbs) Pilot: TLC SUMMARY: 2-PRO's and 6 Candle Lake transects. The last CL transect was flown with the FK which operated at 200 AGL and 3500 MSL. FT also flew the CL transect during transition from SS-OA to SS-OBS & OJP. WEATHER: Flight started with clear skys but small Cu developed from delta to alpha. By the end of the flight, the Cu was 60% at delta and 10% at alpha. The wind was 330 at ? PROBLEM - The O3 sensors were removed for this and all future flights. The last two flights should have had good O3 data. 23 July 1994 Flight time 2.6 hours (Hobbs) Pilot: EJD SUMMARY: 2-PRO's and OJP site specific. WEATHER: Flight started with cloudy skies > 50% cloud cover. Turbulence was extremely rough. Terminated flight early due to extreme turbulence. 24 July 1994 Flight time 5.2 hours (Hobbs) Pilot: TLC SUMMARY: 2-PRO's and 9 FLX L's under clear sky & light North winds. The FT& FK flew the "Grid" during this flight. WEATHER: Clear all day! Winds light and from the north. 24 July 1994 Flight time 4.5 hours (Hobbs) Pilot: EJD SUMMARY: 2-PRO's and 8 FLX L's under clear sky & light North winds. The FT flew the L's at the same time as N3R. WEATHER: Clear all day! Winds light and from the north. Some turbulence early in flight, decaying toward the end. 25 July 1994 Flight time 6.6 hours (Hobbs) Pilot: TLC SUMMARY: Golden day #2. 2-PRO's and 9 CL FLX's under clear sky & calm winds. The FT worked site specifics while FK did CL at 200 AGL & 3500 MSL. There are two flights where FT and FK were on the same transect at close to the same time. WEATHER: Clear all day! Winds very light and from the north. Winds a little stronger to the east. PROBLEM - Channel 4 power controller, which powers the gyros, blew a second fuse. We are now running with a 14A fuse in this channel. Power channels2 & 3 are not working correctly. They were disabled and bypassed with a switch. The dew point has shown some problems on previous flights. The mirror was cleaned before this flight. Audio flight notes were lost during last half of flight. 26 July 1994 Flight time 4.9 hours (Hobbs) Pilot: EJD SUMMARY: Golden day #3. 1-Pitch cal, 1 PRO, and a bunch of OAS FLX's under clear sky & calm winds. WEATHER: Clear all morning! Winds very light and from the southwest. PROBLEM - No equipment problems noted. All sensors appeared to be working well. 26 July 1994 Flight time 4.5 hours (Hobbs) Pilot: TLC SUMMARY: 2-PRO's and 2 OJP asterisk under clear sky & calm winds. WEATHER: Clear all day! Winds very light. Thin smoke/haze layer at ~8000. 27 July 1994 Flight time 1.0 hour (Hobbs) Pilot: EJD SUMMARY: 1 Takeoff file, 1 Pitch cal, 1 river climb, 1 touch & go. WEATHER: Haze layer at 4000' during Pitch cal. Clear otherwise. PROBLEM - No equipment problems noted. All sensors appeared to be working well. 27 July 1994 Flight time 5.9 hours (Hobbs) Pilot: TLC SUMMARY: 2-PRO's and 5 FLX E-W grids under clear sky & low southerly winds. WEATHER: Clear all day however there is a lot of smoke and haze! Winds light. PROBLEM - MFP clock set one day behind. All data files corrected. The last file, which included a PRO, TXI and STC, and its associated markers were lost. NOTE: NSA is now the "hot" site; other aircraft operating in N. The IRGA was cleaned before the flight. 28 July 1994 Flight time 5.8 hours (Hobbs) Pilot: EJD SUMMARY: 2 PRO's and 8 Candle Lake flux runs under clear sky initially, rapid buildup of Cu to approx 40% for last 2 FLX runs. WEATHER: Clear sky for first 4 hours, last 2 hours rapid buildup of approx40% Cu and a thunderstorm near d on last FLX run. 29 July 1994 Flight time 4.1 hours (Hobbs) Pilot: TLC SUMMARY: 2 PRO's and 5 CL FLX under unsettled (variable cloud and some rain) conditions. WEATHER: Front passing through with associated unsetteled conditions. Low small Cu (2000-2500) generated by overnight rain. Stratus at 12000. Winds are calm. 29 July 1994 Flight time Pilot: EJD SUMMARY: 17 legs of Fig 8 pattern at Old Aspen WEATHER: 30 July 1994 Flight time Pilot: EJD SUMMARY: 8 Candle Lake Flux transects 30 August 1994Flight hours 2.1 (Hobbs) SUMMARY: Shakedown flight - some problems encountered, i.e. no angles on first flight, but after rebooting the top card and reloading the antennae vectors, everything with respect to the TANS was up and operating correctly. On the last attempt, however, the gyros were not on. WEATHER: Mostly cloudy all day, with intermittent, moderate rain. Conditions were not conducive for any good Candle Lake transects, or any site specific work. NOTE: The Tp and Th pots were adjusted today, because the Tp was offscale low. The Th pots were accidentally adjusted (thinking they were the Tp's),but they were turned back and both the Tp and the Th look good now. 31 August 1994 Flight time 5.8 hours (Hobbs) SUMMARY: Candle Lake transects WEATHER: Clear in the morning (up to about 10 a.m. local), then small Cu for the remainder of the day (coverage about 25%) 1 September 1994 Flight time 6.2 hours (Hobbs) SUMMARY: Candle Lake transects. WEATHER: Clear in the morning, with Cu building around noon. Coverage was no more than 25%. By 1600L, most of the Cu had dissipated - coverage reduced to about 10% - more to the North. On the transects there was Cu and haze. 3 September, 1994 Flight time 4.4 hours (Hobbs) SUMMARY: Buttonhole patterns over Old Jack Pine. Ground tracks of 030 and 210 deg. WEATHER: Overcast on site for whole flight. Moderate to strong crosswind. 5 September 1994 Flight time 5.0 hours (Hobbs) SUMMARY: Buttonhole patterns at Old Jack Pine and Black Spruce. WEATHER: Clear and calm for takeoff, then around noon the clouds began to form and the winds picked up significantly. Along the flight path, it was turbulent and windy. NOTE: Ozone filter came off sometime during flight 6 September 1994 Flight time 6.2 hours (Hobbs) SUMMARY: Candle Lake transects WEATHER: Clear and calm on takeoff. Winds increased and changed directions in the early afternoon. Sky was clear all day with the exception of a few small Cu to the northeast (less than 5% coverage). There was a gradual windshift at P.A. throughout the day. NOTE: Ozone filter came off sometime during flight (again). 7 September 1994 Flight A Flight time 4.4 hours (Hobbs) SUMMARY: 18 runs by OJP WEATHER: Overcast in the morning with cirrus, clearing by mid-morning but with some cirrus still. 7 September 1994 Flight B Flight time 3.5 (Hobbs) SUMMARY: Buttonhole pattern around the Old Aspen site. WEATHER: Some thin high cirrus, but basically warm and clear. Winds were 110- 120 at 10 most of the day (at P.A.) 8 September 1994 Flight A Flight time 4.4 hours (Hobbs) SUMMARY: Grid pattern. WEATHER: Clear, dry, warm, no wind. 8 September 1994 Flight B SUMMARY: Grid patterns WEATHER: Clear, dry, warm, almost no wind 9 September 1994 Flight time 3.4 hours (Hobbs) SUMMARY: Buttonhole patterns over Old Jack Pine WEATHER: Overcast with cirrus, slight wind, warm and humid 11 September 1994 Flight time 5.4 hours (Hobbs) SUMMARY: Candle Lake transects WEATHER: Started out cloudy, then cleared in the P.A. area. Cool day. EJD said the Candle Lake transect was overcast. NOTE: Time of flight needs fixing. When the data system was started, the computer clock showed 1536 and the GPS showed 1618. 12 September 1994 Flight time 4.8 hours (Hobbs) SUMMARY: Old Jack Pine and Old Aspen buttonhole patterns WEATHER: The day started out overcast and rainy, but around 1030L, it started to clear; then Cu started to form around noon. Cloud cover remained around 25% in the P.A. area. NOTE: Computer time and GPS time were different by about 45 min. (GPS was 1738, computer was 1654. 13 September 1994 Flight time 5.0 hours (Hobbs) SUMMARY: Site specific work over Old Black Spruce to coordinate with Larry Mahrt. Then over to Old Jack Pine to allow Canadian TV to film some flybys. WEATHER: Clear in the P.A. area until noon, then cirrus. Over the OBS it was clear except for some cirrus, and over Old Jack Pine, basically clear conditions. NOTE: TIMES ARE WRONG!! 15 September 1994 Flight time 3.4 hours (Hobbs) SUMMARY: IC with the Twin Otter over the Old Aspen site, then a couple of Candle Lake transects, and a pitch cal. WEATHER: Started out with some clouds, gradually cleared. By 1430 (local) the sky had less than 5% coverage of small Cu, with some cirrus. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage Candle Lake transects covered an approximate 100-km transect; one pass by a tower was approximately 12 km; a grid leg was approximately 15 km; the "L" pattern ranged from 100 to 200 km. The Long-EZ aircraft covered sites in the SSA. The North American Datum 1983 (NAD83) corner coordinates of the SSA are: Longitude Latitude --------- -------- Northwest 106.228° W 54.321° N Northeast 104.237° W 54.225° N Southwest 106.321° W 53.515° N Southeast 104.368° W 53.420° N The tower sites in the SSA include: Site Longitude Latitude BOREAS X BOREAS Y -------------------------------------------------------------------- Old Black Spruce 105.11779° W 53.98717° N 385.012 348.646 Old Jack Pine 104.69203° W 53.91634° N 413.526 343.226 Young Jack Pine 104.64529° W 53.87581° N 416.988 339.008 Fen 104.61798° W 53.80206° N 419.527 330.991 Old Aspen 106.19779° W 53.62889° N 317.198 303.403 7.1.2 Spatial Coverage Map None. 7.1.3 Spatial Resolution The spatial resolution of the original data used in the flux computations is a function of the aircraft speed (50 m/s) and the digital recording rate (40 Hz). This translates to a basic sampling resolution of approximately 1 m for the Long-EZ. However, there is significant natural geophysical variability associated with any turbulence measurement. As a result, statistically significant covariance flux measurement requires space- or time-averaging. The reported data values represent 3-km averages. The basis for the utility of this short average is the Long-EZ's low flight altitude and fast-response data system. The size of flux-transporting turbulence structure decreases (i.e., frequency increases) as the measurement altitude is reduced. This tends to reduce the importance of intermittency, which adversely affects measurements made at higher altitudes. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics These data were collected during the BOREAS IFCs in 1994. The range of dates is from May 25 to September 15, 1994. 7.2.1 Temporal Coverage There were typically two or three flights per day, with 4-5 hour duration each. The days during which data were collected are: May 25, 26, 27, 29, 31, 1994 June 1, 4, 6, 7, 8, 10, 11, 1994 July 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 1994 August 31, 1994 September 1, 3, 5, 6, 7, 8, 9, 11, 12, 13, 15, 1994 7.2.2 Temporal Coverage Map None. 7.2.3 Temporal Resolution The aircraft data were digitized at 200 Hz to allow an oversampling factor of five before recording at 40 Hz. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (mwlezflx.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (mwlezflx.def). 8. Data Organization 8.1 Data Granularity All of the AFM-01 NOAA/ATDD Long-EZ Aircraft Flux Data over the SSA are contained in one data set. 8.2 Data Format(s) The data files contain numerical and character fields of varying length separated by commas. The character fields are enclosed with single apostrophe marks. There are no spaces between the fields. Sample data records are shown in the companion data definition file (mwlezflx.def). 9. Data Manipulations 9.1 Formulae See Section 17.1. 9.1.1 Derivation Techniques and Algorithms See Section 17.1. 9.2 Data Processing Sequence Not available at this revision. 9.2.1 Processing Steps See Section 17.1. 9.2.2 Processing Changes None. 9.3 Calculations 9.3.1 Special Corrections/Adjustments None. 9.3.2 Calculated Variables None. 9.4 Graphs and Plots None. 10. Errors 10.1 Sources of Error None given. 10.2 Quality Assessment 10.2.1 Data Validation by Source Care has been taken in the collection and analysis of the Long-EZ data. The wind measuring system is continually monitored for accuracy using techniques such as wind boxes, control input cases, and intercomparisons with other aircraft. Cospectral plots have been used to check the flux contributions at all wavelengths to ensure that they were not contaminated by inadequate compensation for aircraft motion. 10.2.2 Confidence Level/Accuracy Judgment See Section 10.2.1. 10.2.3 Measurement Error for Parameters Not available. 10.2.4 Additional Quality Assessments Aircraft intercomparison was made by the investigators. 10.2.5 Data Verification by Data Center BORIS staff loaded the data into the database and checked the values to make sure that they were within a reasonable range. 11. Notes 11.1 Limitations of the Data None given. 11.2 Known Problems with the Data See Section 6.2. 11.3 Usage Guidance None given. 11.4 Other Relevant Information None. 12. Application of the Data Set This data can be used to create algorithms to relate boundary-layer processes to satellite-derived data. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description None. 14.2 Software Access Not applicable. 15. Data Access 15.1 Contact for Data Center/Data Access Information These BOREAS data are available from the Earth Observing System Data and Information System (EOS-DIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 15.2 Procedures for Obtaining Data BOREAS data may be obtained through the ORNL DAAC World Wide Web site at http://www-eosdis.ornl.gov/ or users may place requests for data by telephone, electronic mail, or fax. 15.3 Output Products and Availability Requested data can be provided electronically on the ORNL DAAC's anonymous FTP site or on various media including, CD-ROMs, 8-MM tapes, or diskettes. The complete set of BOREAS data CD-ROMs, entitled "Collected Data of the Boreal Ecosystem-Atmosphere Study", edited by Newcomer, J., et al., NASA, 1999, are also available. 16. Output Products and Availability 16.1 Tape Products None. 16.2 Film Products None. 16.3 Other Products These data are available on the BOREAS CD-ROM series. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Anderson, D.E., S.B. Verma, R.J. Clement, D.D. Baldocchi, and D.R. Matt. 1986. Turbulence spectra of CO2, water vapor, temperature and velocity over a deciduous forest. Agricultural and Forest Meteorology, 38: 81-99. Auble, D.L. and T.P. Meyers. 1992. An open path, fast response infrared H2O and CO2 instrument for atmospheric flux measurements. Boundary-Layer Meteorology, 59, 243-256. Crawford, T.L. and R.J. Dobosy. 1992. A sensitive fast-response probe to measure turbulence and heat flux from any airplane. Boundary-Layer Meteorology 59:257-278. Crawford, T.L., R.J. Dobosy, R.T. McMillen, C.A. Vogel, and B.B. Hicks. 1996. Air-surface exchange measurement in heterogeneous regions: extending tower observations with spatial structure observed from small aircraft. Global Change Biology, 2:275-285. Crawford, T.L. and R.T. McMillen. 1991. Direct measurement of CO2 exchange to the ocean using an airborne eddy correlation system. In Proc. of the 7th Conference on Meteorological Observations and Instrumentation, New Orleans, LA, American Meteorological Society, Boston, MA. Preprint Vol. 2.5, pp. 42-45. Crawford, T. L., R.J. Dobosy, and E. Dumas. Aircraft wind measurement considering lift-induced upwash and large attack angles. Boundary-Layer Meteorology (submitted). Crawford, T.L. , R.T. McMillen and R.J. Dobosy. 1991. Description of a "generic" mobile platform using a small airplane and a pontoon boat. In Proc. of the 7th Conference on Meteorological Observations and instrumentation, New Orleans, LA, American Meteorological Society, Boston, MA. Preprint Vol. 2.4, pp. 37-41. Crawford, T.L., T.T. McMillen, and R.J. Dobosy. 1993a. Correcting airborne flux measurements for aircraft speed variation. J. Boundary-Layer Meteorology 66: 237-245. Crawford, T.L., T.T. McMillen, T.P. Meyers, and B.B. Hicks. 1993b. The spatial and temporal variability of heat, mass, and momentum air-sea exchange in a coastal environment. J. Geophysical Research, 98:12,869-12,869. Crawford, T.L., T.T. McMillen, and R.J. Dobosy. 1990. Development of a "Generic" Mobile Flux Platform with Demonstration on a Small Airplane. NOAA Technical Memorandum ERL ARL-184. McMillen, R.T. and T.L. Crawford. 1991. Direct measurement of CO2 exchange to the ocean using a ship mounted eddy correlation system. In Proc. of the 7th Conference on Meteorological Observations and Instrumentation, New Orleans, LA, American Meteorological Society, Boston, MA. Preprint Volume 2.6, pp. 46-50. 17.2 Journal Articles and Study Reports Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). Sellers, P. and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96). Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94). Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den Hartog, J. Cihlar, M.G. Ryan, B. Goodison, P. Crill, K.J. Ranson, D. Lettenmaier, and D.E. Wickland. 1995. The boreal ecosystem-atmosphere study (BOREAS): an overview and early results from the 1994 field year. Bulletin of the American Meteorological Society. 76(9):1549-1577. Sellers, P.J., F.G. Hall, R.D. Kelly, A. Black, D. Baldocchi, J. Berry, M. Ryan, K.J. Ranson, P.M. Crill, D.P. Lettenmaier, H. Margolis, J. Cihlar, J. Newcomer, D. Fitzjarrald, P.G. Jarvis, S.T. Gower, D. Halliwell, D. Williams, B. Goodison, D.E. Wickland, and F.E. Guertin. 1997. BOREAS in 1997: Experiment Overview, Scientific Results and Future Directions. Journal of Geophysical Research 102 (D24): 28,731-28,770. Webb, E. K., G. I. Pearman, and R. Leuning. 1980. Correction of flux measurements for density effects due to heat and water vapour transfer. Quarterly Journal of the Royal Meteorological Society, 106:85-100. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List of Acronyms AFM - Airborne Flux and Meteorology ASCII - American Standard Code for Information Interchange ATDD - Atmospheric Turbulence and Diffusion Division BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System CD-ROM - Compact Disk-Read-Only-Memory CG - Center of Gravity DAAC - Distributed Active Archive Center DGPS - Differential Global Positioning System EOS - Earth Observing System EOSDIS - EOS Data and Information System GPS - Global Positioning System GSFC - Goddard Space Flight Center HTML - HyperText Markup Language IFC - Intensive Field Campaign IRGA - Infrared Gas Analyzer NAD83 - North American Datum of 1983 NASA - National Aeronautics and Space Administration NOAA - National Oceanic and Atmospheric Administration NSA - Northern Study Area OA - Old Aspen OJP - Old Jack Pine OBS - Old Black Spruce ORNL - Oak Ridge National Laboratory PANP - Prince Albert National Park PAR - Photosynthetically Active Radiation POD - Processed Output Data QA - Quality Assurance SSA - Southern Study Area URL - Uniform Resource Locator 20. Document Information 20.1 Document Revision Date Written: 01-Jan-1995 Last Updated: 13-Aug-1999 20.2 Document Review Date(s) BORIS Review: 14-June-1999 Science Review: 20.3 Document ID 20.4 Citation Long-EZ aircraft flux data were collected by NOAA's Atmospheric Turbulence and Diffusion Division (ATDD). 20.5 Document Curator 20.6 Document URL Keywords --------- CARBON DIOXIDE METHANE BOUNDARY LAYER WATER MIXING RATIO OZONE PHOTOSYNTHETICALLY ACTIVE RADIATION AFM01_Moving_Window.doc 08/21/99