BOREAS TF-08 NSA-OJP Tower Flux, Meteorological, and Soil Temperature Data Summary The BOREAS TF-08 team collected energy, CO2, and water vapor flux data at the BOREAS NSA-OJP site during the growing season of 1994 and most of the year for 1996. The data are available 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 TF-08 NSA-OJP Tower Flux, Meteorological, and Soil Temperature Data 1.2 Data Set Introduction This study focused on long-term measurements of radiation, heat, moisture, CO2, and momentum budgets from the tower at the BOReal-Ecosystem-Atmosphere Study (BOREAS) Northern Study Area (NSA) Old Jack Pine (OJP) site. Turbulent fluxes were determined using the eddy correlation technique, and radiative fluxes in the short, long, near-infrared, and Photosynthetically Active Radiation (PAR) wavelength bands were acquired as well. Also, soil moisture content data were collected. Collaborating with other groups the CO2 gradient inside and just above the canopy were acquired. In addition, a digital cloud camera was used to obtain a seasonal record of cloud fraction and cloud type. 1.3 Objective/Purpose The objective was to make measurements of the components of the energy and radiation balances over an old jack pine forest in the Canadian boreal forest ecosystem during a period of time encompassing a large portion of a growing season. These measurements, together with direct measurements of the CO2 flux, provide a view of ecosystem functioning on a wide range of time scales. In addition, the contribution of jack pine landcover to the regional fluxes of heat, water vapor, momentum, and CO2 was assessed. 1.4 Summary of Parameters Turbulent flux measurements included above- and below- canopy measurements of sensible and latent heat fluxes, CO2 flux, and friction velocity. Gradient measurements included vertical profiles of wind speed, relative and specific humidity, and air temperature. Radiative measurements included net radiation, upwelling and downwelling PAR, upwelling and downwelling global shortwave radiation, upwelling and downwelling longwave radiation, surface temperature, and undercanopy net radiation. Meteorological measurements included wind speed and direction, air pressure, and rainfall. Soil measurements included: soil water potential, soil temperature, and soil heat flux. These measurements were collected at different locations with different ground covers. The soil temperatures were collected at multiple depths. 1.5 Discussion The objectives of this study were to obtain the time series of the elements in the surface energy and water balance during the growing season at the BOREAS NSA-OJP in order to provide data to investigate vegetation-atmosphere models; to relate the vertical wind profile to the frequency and type of coherent turbulent eddies in the canopy layer; and to relate components of radiation budget, the observed cloud fraction, type, and height to develop feedback relationships between surface heat and water vapor fluxes and convective cloud cover. By making redundant measurements of the components of the energy balance, uncertainty is reduced and the possibility of discovering the true balance is increased. Gradient measurements are of interest in their own right, for instance, to obtain estimates of the displacement height. Each measurement has its own footprint. For example, the sonic anemometer at tower top is looking at an area perhaps 200-500 m upwind of the sensor, while the net radiometer is measuring a smaller area closer to the tower. 1.6 Related Data Sets BOREAS TF-05 SSA-OJP Tower Flux, Meteorological, and Soil Temperature Data BOREAS TF-03 NSA-OBS Tower Flux, Meteorological, and Soil Temperature Data BOREAS TF-08 NSA-OJP and SSA-OBS Ceilometer Data BOREAS TF-10 NSA-YJP Tower Flux, Meteorological, and Biophysical Data BOREAS TF-10 NSA-Fen Tower Flux and Meteorological Data 2. Investigator(s) 2.1 Investigator(s) Name and Title David R. Fitzjarrald Research Associate Atmospheric Sciences Research Center (ASRC) Kathleen E. Moore Research Scientist ASRC 2.2 Title of Investigation Surface Exchange Observations in the Canadian Boreal Forest Region 2.3 Contact Information Contact 1 --------- Kathleen E. Moore Research Scientist Atmospheric Sciences Research Center Albany, NY (518) 437-8732 (518) 437-8758 (fax) moore@asrc.cestm.albany.edu Contact 2 --------- David R. Fitzjarrald Research Associate Atmospheric Sciences Research Center Albany, NY (518) 437-8735 (518) 437-8758 (fax) fitz@asrc.cestm.albany.edu Contact 3 --------- K. Fred Huemmrich University of Maryland NASA GSFC Greenbelt, MD (301) 286-4862 (301) 286-0239 (fax) Karl.Huemmrich@gsfc.nasa.gov 3. Theory of Measurements The boreal forest is important to the global energy and carbon balance, due partly to the large area covered by this vegetation type. Measurements on a wide variety of time and space scales are required in order to achieve an integrated understanding of these balances and the factors that affect them from day to day and over a growing season. Tower-based measurements provide ground truth for satellite and other remote sensing measurements. Eddy correlation estimates represent the only direct measurements of fluxes. Auxiliary measurements, e.g., soil, gradients, etc., are of fundamental importance. For example, it may be possible to use a similarity argument for water vapor and CO2 to get the CO2 storage term at night by examining how humidity builds up in the stable surface layer. Eddy correlation measurements are accomplished by simply calculating the covariance between the fluctuating vertical velocity and the fluctuating scalar or vector quantity of interest. 4. Equipment 4.1 Sensor/Instrument Description 4.1.1 Collection Environment Measurements were collected from late May through mid-September 1994 and mid- April through mid-November of 1996. Over that time period, temperature conditions from less than –15 °C to over 30 °C were experienced. 4.1.2 Source/Platform A 30-m Rohn communications tower was used throughout the experiment. Turbulent fluxes were measured at the top of the tower and at 13 m (until 29-Jul-1994, when a separate, 2-m mast was erected for subcanopy fluxes). In 1994, the subcanopy flux measurements were made in an open, lichen-covered area approximately 15 m west of the tall tower. In 1996, the subcanopy array was erected on 09-Jul in a moss-covered area to the north of the tower. 4.1.3 Source/Platform Mission Objectives The purpose of the tower was to support instruments to measure energy, water, and CO2 fluxes and related environmental variables above and within an old jack pine forest. 4.1.4 Key Variables Turbulent flux measurements included above- and below-canopy measurements of sensible and latent heat fluxes, CO2 flux, and friction velocity. Gradient measurements included vertical profiles of wind speed, relative and specific humidity, and air temperature. Radiative measurements included net radiation, upwelling and downwelling PAR, upwelling and downwelling global shortwave radiation, upwelling and downwelling longwave radiation, surface temperature, and undercanopy net radiation. Meteorological measurements included wind speed and direction, air pressure, and rainfall. Soil measurements included soil water potential, soil temperature, and soil heat flux. These measurements were collected at different locations with different ground covers. The soil temperatures were collected at multiple depths. 4.1.5 Principles of Operation Eddy correlation variables were acquired at a 10-Hz rate. Serial output from the 3-axis and 1-axis sonic anemometers was collected directly at serial ports in a Sun workstation. In 1994, the 3-axis anemometer was set up to receive a strobe signal from a Harrison datalogger in order to synchronize the sonic measurements with the scalar eddy quantities (e.g., water vapor and CO2). The same Harrison datalogger received the analog signals of the scalars and performed the analog to digital conversion. These data were passed to the Sun in a separate serial stream. A fourth serial stream contained data from the slower response radiation and gradient measurements, converted to digital form by a separate Harrison datalogger. Acquisition for this group of signals was at 0.02 Hz. A custom digital counter board kept count of the cup anemometer rotations; the datalogger read these at a 40-Hz rate and reset the counters every 5 seconds. In 1994, analog signals from the upper sonic (3-axis) anemometer were also acquired by the Harrison logger. In 1996, only analog signals from the sonic anemometers were acquired. Campbell Scientific 21x dataloggers were used as backup acquisition systems for the radiation, gradient, and flux (upper level) systems. A separate Campbell Scientific 21x datalogger was dedicated to the soil measurements. Two Campbell Scientific 21x dataloggers were assigned as backup acquisition systems for the Harrison loggers. 4.1.6 Sensor/Instrument Measurement Geometry Sonic anemometers were mounted at heights of 30 m and 13 m above ground level. Temperature and humidity gradient measurements were collected at 22.68-m, 15.65- m, 9.32-m, and 4.22-m heights. Wind speed gradient measurements were collected at 18.88-m, 14.65-m, 11.32-m, 9.32-m, 6.35-m, and 1.92-m heights. Radiation measurements, including net radiation, incident and reflected global shortwave radiation, incident and reflected global longwave radiation, incident and reflected PAR, and the temperatures of the upwelling and downwelling longwave radiation were measured at 27-m height. Subcanopy measurements of net radiation were collected at 1-m height in an open lichen covered area, and at 1.5-m in an area under a closed canopy. In 1994, soil temperature profiles were taken at three locations: a lichen- covered area between two jack pines, a moss-covered area under the jack pine canopy, and an area covered with a mixture of moss and lichen. At the lichen- covered site, soil temperatures were collected at 2.5-cm, 7.5-cm, and 20-cm depths. At the moss-covered site soil temperatures were collected at 2.5-cm, 10-cm, and 22.5-cm depths. At the mixed site, soil temperatures were collected at 2.5-cm, 7.5-cm, and 20-cm depths. At all three sites, soil heat flux was measured at 4-cm depth and soil water potential was measured using gypsum soil moisture blocks at the lichen- and moss-covered areas at a depth of 8-cm. In 1996, there were three sites for soil measurements: a closed site, a semiclosed site, and an open site. At the closed site, soil temperature measurements were collected at 6.4-cm, 14-cm, and 26.7-cm depths. At both the semiclosed and open sites, soil temperature data were collected at 2.5-cm, 10.2-cm, and 22.8-cm depths. Soil heat fluxes were measured at 10.2-cm depth at the closed site, and at 6.4-cm depth at the semiclosed and open sites. In 1994, three different rainfall measurements were collected. One measurement was made from a 3-m trough (vinyl rain gutter) under the jack pine canopy using an MRI tipping bucket rain gauge. The collecting area for this gauge was expanded 9 times by using the trough. A second rain gauge was located at 0.5-m height in the opening between jack pine trees. A third rainfall measurement was collected from a gauge located at 15 m on the flux tower. These other two rain gauges were both Campbell Scientific model TE525. In 1996, rainfall data were collected from the trough and tower rain gauges. 4.1.7 Manufacturer of Sensor/Instrument 3-axis and 1-axis sonic anemometers: Applied Technologies, Inc. 1120 Delaware Ave. Longmont, CO 80501 (303) 684-8722 (303) 684-8773 (fax) sales@apptech.com Kipp and Zonen CG-2(net longwave) and CM14 (albedometer): Kipp & Zonen P.O. Box 507 2600AM Delft The Netherlands +31 15 269 8000 +31 15 262 0351 (fax) LI-COR LI-190SA PAR sensors, LI6262 CO2,H2O instrument: LI-COR, Inc. 4421 Superior Street P.O. Box 4425 Lincoln, NE 68504 (402) 467-3576 Swissteco type S-1 Net Pyradiometer: Swissteco Pty., Ltd. Melbourne, Victoria Australia 31. Campbell Scientific Krypton hygrometers, soil temperature model 107, soil heat flux model HFT-1: Campbell Scientific, Inc. 815 West 1800 North Logan, UT 84321-1784 (435) 753-2342 (435) 750-9540 (fax) info@campbellsci.com Vaisala air temperature and relative humidity probes. Temperature measured with AD590 IC temperature transducer, relative humidity probe was humi-cap resistance device: Vaisala, Inc. U.S. Office 100 Commerce Way Woburn, MA 01801-1068 (781) 933-4500 Gill propeller-vane anemometer: Gill Instruments Limited Solent House Cannon Street Lymington, Hampshire SO41 9BR UK +44 (0)1590 679955 +44 (0)1590 676409 (fax) Met One model 014A cup wind speed sensor and radiation shield (with fan): Met One Instruments, Inc. 1600 Washington Blvd. Grants Pass, OR 97526 (541) 471-7111 (541) 471-7116 (fax) 4.2 Calibration 4.2.1 Specifications Kipp and Zonen albedometer and pyrgeometer used factory calibration. The pyrgeometer was also factory calibrated on 13-Nov-1995. The upwelling and downwelling longwave temperature represent temperatures for the two thermopiles, measured with PT-100 devices. Following the 1993 Intensive field Campaign (IFC), a laboratory calibration was done on these instruments, and corrections were determined and applied to the data in postprocessing. Similar tests were run following the 1996 field season. Net Radiometer comparisons with sum of components was done continuously. The two subcanopy net radiometers were compared with the above-canopy instrument in the spring of 1993 at the Atmospheric Sciences Research Center (ASRC). The air temperature and relative humidity probes were laboratory calibrated after the 1993 IFC. Corrections have been applied to the archived data. The CO2 instrument was field calibrated using 1% CO2 in air. Zero and span calibrations were carried out prior to each field season. The instrument was sent for overhaul and factory recalibration after the 1994 field season. Krypton hygrometers were calibrated at the factory in 1993 and 1995. In postprocessing, regressions of the natural log of the voltage on the water vapor density determined from the air temperature and relative humidity probes were done. These daily, "field" regressions were used in place of the factory calibration for the upper Krypton hygrometer in 1994, and for both Krypton hygrometers in 1996. The LI-COR water vapor instrument was calibrated at the factory before each field season. "Field calibrations" (regression of output against actual field water vapor density measurements) as described above for the Krypton hygrometers were used to convert voltages to water vapor density. 4.2.1.1 Tolerance Applied Technologies 3-axis and 1-axis sonic anemometers: Sensitivity: u, v, and w wind speeds: 0.01 m/s Accuracy: wind speed ± 1%; wind direction ± 0.1° Response time: <0.1 s Kipp and Zonen CG-2(net longwave) and CM14 (albedometer): Sensitivity: shortwave measurements: approximately 4 µV/(W m-2); longwave Measurements: approximately 10 µV/(W m-2) Accuracy: within 1% Response time: 30 s LiCor LI-190SA PAR sensors: Sensitivity: 8 µA/(1000 µmol s-1 m-2) Accuracy: ± 5% Response time: 10 µs Swissteco type S-1 Net Pyradiometer: Sensitivity: 0.48 mV/(mW cm2) Accuracy: ± 2.5% Response time: 30s LI-COR LI6262 CO2, H2O instrument (fast response option). Air was drawn down 3/8" Teflon tubing by a 30-liters per minute (lpm) pump. The sensor was placed in a side stream drawn off with a 10-lpm pump. A flow controller was placed in the stream going to the sensor to limit the flow through the sensor to 1 lpm, in 1994, or 2 lpm in 1996. Sensitivity: 0.1-0.5 ppm/mv Response time: < 0.5 s Campbell Scientific Krypton hygrometers: Sensitivity: 105 mV/gm-3 Response time: 0.1 s Vaisala air temperature and relative humidity probes were installed in Met One radiation shields (with fans). Temperature was measured with AD590 IC temperature transducers, fed into a custom circuit, and calibrated in the lab in mineral oil in a precision temperature bath. Relative humidity probes were humi-cap resistance devices. Sensitivity: Temperature - 0.01 °C /mV; Relative humidity (RH) 0.1% RH/mV Accuracy: Temperature ± 0.01 °C; Relative humidity 3% Response time: Temperature (AD590) 10 s; Relative humidity 15 s Soil thermistors: Campbell Scientific 107 temperature probes. Accuracy: 0.2 °C Response time: 10 s A Gill propeller-vane anemometer was mounted on the tower at 25.7. At the six remaining lower heights, Met-one model 014A cup wind speed sensors were used: Threshold: cups: 0.5 m/s; Gill: 0.1-0.2 m/s Accuracy: cups: ± 1.5%; Gill: unknown Distance constant: cups: 4.6 m; Gill: 1 m (speed), 1.2 m (direction) Rain gauge: Campbell Scientific model TE525 Precision: 0.1 mm Rain gauge: MRI tipping bucket: Precision: 0.256 mm Total area collected: 0.290 m2 4.2.2 Frequency of Calibration See Section 4.2.1. 4.2.3 Other Calibration Information Webb corrections were applied to vapor density fluxes, to account for effect of density fluctuations on flux estimates (Webb et al., 1980). The effect of water vapor flux on the heat capacity of air was also accounted for in the conversion from kinematic heat flux to W/m2. The effect of oxygen absorption in the ultraviolet (UV) was corrected for in calculating water vapor flux from the krypton hygrometer (Campbell and Tanner, 1985). The air temperature and relative humidity probes were laboratory calibrated after the 1993 IFC. The laboratory calibration yielded these corrections: T_22.7m = 0.01013*(mv) + 0.00075 T_15.7m = 0.0103*(mv) + 0.00257 T_9.3m = 0.0101*(mv) + 0.00278 T_4.2m = 0.01001*(mv) + 0.00125 The air temperature variables are represented in the form where T_22.7m is the air temperature at 22.7 m height, and mv is the instrument output in millivolts. 5. Data Acquisition Methods Eddy correlation variables were acquired at a 10-Hz rate. Serial output from the 3-axis and 1-axis sonic anemometers was collected directly at serial ports in a Sun workstation. In 1994, the 3-axis anemometer was set up to receive a strobe signal from a Harrison datalogger in order to synchronize the sonic measurements with the scalar eddy quantities (e.g., water vapor and CO2). The same Harrison datalogger received the analog signals of the scalars and performed the analog to digital conversion. These data were passed to the Sun in a separate serial stream. A fourth serial stream contained data from the slower response radiation and gradient measurements, converted to digital form by a separate Harrison datalogger. Acquisition for this group of signals was at 0.02 Hz. A custom digital counter board kept count of the cup anemometer rotations; the datalogger read these at a 40-Hz rate and reset the counters every 5 seconds. In 1994, analog signals from the upper sonic (3-axis) anemometer were also acquired by the Harrison logger. In 1996, only analog signals from the sonic anemometers were acquired. Campbell Scientific 21x dataloggers were used as backup acquisition systems for the radiation, gradient, and flux (upper level) systems. A separate Campbell Scientific 21x datalogger was dedicated to the soil measurements. Two Campbell Scientific 21x dataloggers were assigned as backup acquisition systems for the Harrison loggers. A sky imaging system was located on the roof of the hut. In 1993 and 1994, the imaging system consisted of one charged coupled device (CCD) with image acquisition hardware and software. This system used fish-eye and 28-mm lenses and produced digitized images with 256 by 244 pixels and 64 gray scales. In 1996, video images were digitized in 24-bit color using joint photographic experts group (jpg) format, with 751 by 484 pixels and 256 levels each of red, green, and blue. 6. Observations 6.1 Data Notes Gaps in the data in all years occur due to instrument failure or computer failure. 6.2 Field Notes Field notes are contained in four notebooks located at ASRC in Albany. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage All data were collected at the BOREAS NSA-OJP site. The North American Datum of 1983 (NAD83) coordinates for the NSA-OJP tower were latitude 55.92842° N, longitude 98.62396° W, and elevation of 255.1 m. Turbulent fluxes were measured at the top of the flux tower, and at 13 m high on the flux tower, until 29-Jul-1994, when a separate 2-m-tall mast was erected for subcanopy fluxes. In 1994, the subcanopy flux measurements were made in an open, lichen-covered area approximately 15 m west of the main tower. In 1996, the subcanopy array was erected on 09-Jul in a moss-covered area to the north of the tower. Soil temperature and heat flux measurements were made at three sites chosen for their microsite variation (mossy cover, lichen cover, and intermediate). These sites were all 30-40 m from the flux tower in the northwest direction. The sky camera was placed on the roof of the shack at the site. The ceilometer was located on the tent platform to the south of the shack. Subcanopy net radiation measurements in 1994 were made in an open area and an area of denser canopy, to the north of the flux tower. One rain gauge was located on the flux tower at 15 m, one was in the subcanopy layer in an opening, and a third collected rain from a trough 10 feet long under closed canopy. 7.1.2 Spatial Coverage Map Not applicable. 7.1.3 Spatial Resolution Data collected from flux towers are often thought of as point data. However, particularly in terms of the eddy flux data, they actually represent an integrated upwind source region. The size of the region being sampled is related to factors such as the height of the tower, the roughness of the canopy, and the wind speed. 7.1.4 Projection None. 7.1.5 Grid Description None. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage Data collection in 1993 covered the following dates: Turbulent fluxes: 11-Aug to 29-Aug-1993 Soil measurements: 11-Aug to 29-Aug-1993 Water vapor flux: 20-Aug to 29-Aug-1993 CO2 flux : 23-Aug to 29-Aug-1993 Radiative fluxes: 14-Aug to 29-Aug-1993 Gradient measurements: 14-Aug to 29-Aug-1993 Sky camera images: 17-Aug to 29-Aug-1993 Data collection in 1994 covered the following dates: Turbulent fluxes: 24-May to 19-Spt-1994 Second level fluxes moved from 13 m to 2 m on 29-Jul-1994 Soil measurements: 28-May to 19-Sep-1994 Radiative fluxes: 24-May to 19-Sep-1994 Gradient measurements: 24-May to19-Sep-1994 Sky camera images: 01-Jun to 19-Sep-1994 Ceilometer measurements: 28-May 28 to 17-Sep-1994 Data collection in 1996 covered the following dates: Turbulent fluxes: 15-Apr to 09-Nov-1996 Second level fluxes: 19-Jul to 09-Nov-1996 Second level CO2 flux: 26-Sep to 09-Nov-1996 Soil measurements: 25-May to 09-Nov-1996 Radiative fluxes: 15-Apr to 09-Nov-1996 IR thermometers: 20-Jul to 09-Nov-1996 Gradient measurements: 15-Apr to 09-Nov-1996 Sky camera images: 6-May to 09-Nov-1996 Ceilometer measurements: 29-May to 09-Nov-1996 7.2.2 Temporal Coverage Map None. 7.2.3 Temporal Resolution The 1996 data were averaged over 30-minute periods. The 1993 and 1994 data were averaged over 20-minute periods. These data were then interpolated to 30-minute time periods. 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (tf08tflx.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (tf08tflx.def). 8. Data Organization 8.1 Data Granularity All of the TF-08 NSA-OJP Tower Flux, Meteorological, and Soil Temperature Data are contained in one dataset. 8.2 Data Format 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 (tf08tflx.def). 9. Data Manipulations 9.1 Formulae 9.1.1 Derivation Techniques and Algorithms Eddy correlation measurements are accomplished by simply calculating the covariance between the fluctuating vertical velocity and the fluctuating scalar or vector quantity of interest. 9.2 Data Processing Sequence 9.2.1 Processing Steps Averages were calculated over 20-minute periods in 1993 and 1994, and over 30- minute periods in 1996. Eddy variables had a 4-minute running mean removed from them. The Sun workstation received the serial data and put a time stamp on each "chunk" of data representing 10 seconds. The four serial streams were synchronized using these time stamps. To make eddy correlation estimates of scalars, a more precise synchronization was provided by the lagged cross- correlation. This procedure was also used to provide the appropriate lag for the LI-COR CO2 and H2O signals, as there was a separate delay introduced by the time it took air to travel down the tubing to the sensor. Data submitted to the archive were interpolated to half-hour intervals. Power spectra, co- and quad-spectra, and moments (up to the 4th) were calculated in real time, in the normal acquisition routine. Post-IFC calculations were redone after the 1993 field campaign. The coordinate rotation of McMillan et al. (1986) was done for the 3-axis sonic. CO2 fluxes were calibrated to ppm-m/s. The conversion from CO2 flux in ppm-m/s to mg/(m2 s) is: (1e-3*44*Pa)/(R*Tk), where Pa is the surface atmospheric pressure (kPa), R is gas constant, and Tk is the ambient air temperature (K). In the processing of the flux data, a program read in the daily calibration data for latent heat and for CO2 fluxes, and also made the following corrections: a. Specific heat capacity of air was corrected for effects of vapor. b. The water vapor flux from the Krypton hygrometer was corrected for oxygen absorption. c. The Webb (Webb et al., 1980) correction was applied. Outliers were then removed from the data set. Finally, these data, which were still on the original 20-minute time base, were interpolated to the half-hour. BORIS staff processed these data by: 1) Reviewing the initial data files and loading them online for BOREAS team access. 2) Designing relational data base tables to inventory and store the data. 3) Loading the data into the relational data base tables. 4) Working with the team to document the data set. 5) Extracting the data into logical files. 9.2.2 Processing Changes The 1996 data were averaged over 30 minute periods. The 1993 and 1994 data were averaged over 20-minute periods. These data were then interpolated to 30-minute time periods. 9.3 Calculations 9.3.1 Special Corrections/Adjustments The trough rain gauge values represent a direct measurement from that gauge. No correction was made to compensate for the increase of the collection area. The collecting area for this gauge was expanded 9 times by using the trough. Theten's equation was used to calculate the mixing ratio. Pressure corrections due to different height locations on the tower were considered using hydrostatic equation. The air density was held constant at 1.212 g m-3. 9.3.2 Calculated Variables All of the turbulent flux values were calculated, including sensible and latent heat fluxes, CO2 flux, and friction velocity. 9.4 Graphs and Plots None. 10. Errors 10.1 Sources of Error Webb corrections were applied to vapor density fluxes, to account for the effect of density fluctuations on flux estimates (Webb et al., 1980). The effect of water vapor flux on the heat capacity of air was also accounted for in the conversion from kinematic heat flux to W m-2. The effect of oxygen absorption in the UV was corrected for in calculating water vapor flux from the krypton hygrometer (Campbell and Tanner, 1985). 10.2 Quality Assessment None given. 10.2.1 Data Validation by Source Net radiometer comparisons with the sum of components was done continuously. 10.2.2 Confidence Level/Accuracy Judgment See Section 4.2.1.1. 10.2.3 Measurement Error for Parameters See Section 4.2.1.1. 10.2.4 Additional Quality Assessments None. 10.2.5 Data Verification by Data Center Data were examined to check for spikes, values that are four standard deviations from the mean, long periods of constant values, and missing data. 11. Notes 11.1 Limitations of the Data None given. 11.2 Known Problems with the Data In 1994, the PAR sensors had offsets in them that can be readily identified by looking at the nighttime data. Problems with lags in the analog versus the serial-stream data in 1994 caused us to recalculate fluxes using only the analog sonic signals velocity. 11.3 Usage Guidance All investigators are urged to contact D. Fitzjarrald or K. Moore concerning questions about data handling or instrument capability. 11.4 Other Relevant Information None. 12. Application of the Data Set These data are useful for the study of water, energy, and carbon exchange in a mature jack pine forest. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description None given. 14.2 Software Access None given. 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 None. 17.2 Journal Articles and Study Reports Campbell, G.S. and B.D. Tanner. 1985. A Krypton hygrometer for measurement of atmospheric water vapor concentration. Proc. Int. Symposium on Humidity and Moisture. Instrument Society of America. pp. 609-614. Funk, J.P. 1959. Improved polythene-shielded net radiometer. J. Sci. Inst. 36: 267-270. McMillen, R.T. 1986. A BASIC program for eddy correlation in non-simple terrain. NOAA Tech. Memo. ERL-ARL-147. 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):28,731-28,769. Webb, E.K., G.I. Pearman, and R. Leuning. 1980. Correction of flux measurements density effects due to heat and water vapour transfer. Quart. J. R. Met. Soc. 106:85-100. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms None. 19. List of Acronyms ASCII - American Standard Code for Information Interchange ASRC - Atmospheric Sciences Research Center ATD - Atmospheric Technology Division ATI - Applied Technologies, Inc. BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System CCD - Charged Coupled Device CD-ROM - Compact Disk-Read-Only Memory DAAC - Distributed Active Archive Center EOS - Earth Observing System EOSDIS - EOS Data and Information System GMT - Greenwich Mean Time GSFC - Goddard Space Flight Center HTML - Hyper-Text Markup Language IFC - Intensive Field Campaign jpg - Joint Photographic experts Group lpm - Liters Per Minute NAD83 - North American Datum of 1983 NASA - National Aeronautics and Space Administration NCAR - National Center for Atmospheric Research NEP - Net Ecosystem Productivity NSA - Northern Study Area OBS - Old Black Spruce OJP - Old Jack Pine ORNL - Oak Ridge National Laboratory PAR - Photosynthetically Active Radiation ppm - Parts Per Million SSA - Southern Study Area TF - Tower Flux URL - Uniform Resource Locator UV - Ultraviolet YJP - Young Jack Pine 20. Document Information 20.1 Document Revision Date Written: 21-May-1999 Revised: 20-Sep-1999 20.2 Document Review Date(s) BORIS Review: 07-Jun-1999 Science Review: 20.3 Document ID 20.4 Citation When using these data, please include the following acknowledgment: These data were provided by Drs. David R. Fitzjarrald and Kathleen E. Moore. If using data from the BOREAS CD-ROMs please also reference the data as: Dr. David R. Fitzjarrald and Dr. Kathleen E. Moore, "Surface Exchange Observations in the Canadian Boreal Forest Region." in Collected Data of The Boreal Ecosystem-Atmosphere Study. Eds. J. Newcomer, D. Landis, S. Conrad, S. Curd, K. Huemmrich, D. Knapp, A. Morrell, J. Nickeson, A. Papagno, D. Rinker, R. Strub, T. Twine, F. Hall, and P. Sellers. CD-ROM. NASA, 1999. To cite the BOREAS CD-ROM set as a published volume, use: J. Newcomer, D. Landis, S. Conrad, S. Curd, K. Huemmrich, D. Knapp, A. Morrell, J. Nickeson, A. Papagno, D. Rinker, R. Strub, T. Twine, F. Hall, and P. Sellers, eds. Collected Data of The Boreal Ecosystem-Atmosphere Study. CD-ROM. NASA, 1999. 20.5 Document Curator 20.6 Document URL Keywords AIR TEMPERATURE CARBON DIOXIDE CONCENTRATION CARBON DIOXIDE FLUX JACK PINE LATENT HEAT FLUX LONGWAVE RADIATION METEOROLOGY NET RADIATION PAR PHOTOSYNTHETIC PHOTON FLUX DENSITY PHOTOSYNTHETICALLY ACTIVE RADIATION PPFD RAINFALL SENSIBLE HEAT FLUX SOIL HEAT FLUX SOIL TEMPERATURE SOIL WATER POTENTIAL SPECIFIC HUMIDITY TOWER FLUX VAPOR PRESSURE WIND SPEED TF08_Flux.doc 09/30/99