BOREAS Derived Surface Meteorological Data Summary In 1995, the BOREAS science teams identified the need for a continuous surface meteorological and radiation data set to support flux and surface process modeling efforts. This data set contains actual, substituted, and interpolated 15-minute meteorological and radiation data compiled from several surface measurements sites over the BOREAS SSA and NSA. Temporally, the data cover 01- Jan-1994 to 31-Dec-1996. 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 Derived Surface Meteorological Data 1.2 Data Set Introduction The 1994-96 surface meteorological modeling data set contains actual and 'derived' 15-minute meteorological and radiation data from four BOReal Ecosystem-Atmosphere Study (BOREAS) sites. These surface meteorological data were compiled to create a continuous set of surface meteorological and radiation parameters (i.e., no data gaps) for use by BOREAS modeling groups. The data were compiled from various meteorological measurement sites in the BOREAS Northern Study Area (NSA) and Southern Study Area (SSA). Data gaps were filled by interpolation or substitution depending on the length of time that data were missing. If the gap was 2 hours or less, the data were interpolated. For data gaps greater than 2 hours, the data were filled with data from other instruments from the same study area. 1.3 Objective/Purpose This data set was compiled in order to provide a continuous surface meteorological data set for use in modeling activities. 1.4 Summary of Parameters Parameters include: Date Time Air Temperatures Pressure Humidity Wind Components Precipitation Snow Depth Radiation Fields Soil Temperatures 1.5 Discussion The BOREAS Staff Science effort covered those activities that were BOREAS community-level activities or required uniform data collection procedures across sites and time. These activities included the compilation of integrated data sets for various purposes. These meteorological data were compiled to create a continuous set of surface meteorological and radiation parameters (i.e., no data gaps) for use in various modeling efforts. 1.6 Related Data Sets The data sets used in creating this data set are: BOREAS AFM-07 SRC Surface Meteorological Data BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data Atmospheric Environment Service (AES) Thompson Airport Snow and Precipitation Reports Related data sets include: BOREAS AES Campbell Scientific Surface Meteorological Data BOREAS AES READAC Surface Meteorological Data BOREAS AES MARSII Surface Meteorological Data BOREAS AFM-05 Level-1 Upper Air Network Data BOREAS AFM-05 Level-2 Upper Air Network Standard Pressure Level Data 2. Investigator(s) 2.1 Investigator(s) Name and Title BOREAS Staff Science 2.2 Title of Investigation BOREAS Staff Science Meteorological Data Acquisition Program 2.3 Contact Information Contact 1 ----------- David Knapp Raytheon ITSS NASA GSFC Greenbelt, MD (301) 286-1424 (301) 286-0239 (fax) David.Knapp@gsfc.nasa.gov Contact 2 ----------- Jeffrey Newcomer Raytheon ITSS NASA GSFC Greenbelt, MD (301) 286-7858 (301) 286-0239 (fax) Jeffrey.Newcomer@gsfc.nasa.gov 3. Theory of Measurements This data set was compiled in order to provide a continuous and standard surface meteorological data set for modeling efforts. The majority of the measurements were made from BOREAS Saskatchewan Research Council (SRC) towers, which were generally collocated with BOREAS flux towers. Other SRC tower sites were spread across the BOREAS region. The SRC network provided meteorological data representative of the BOREAS region to be used in conjunction with other BOREAS data sets to better understand the climate of the boreal region. 4. Equipment 4.1 Sensor/Instrument Description The following provides a list of the instruments used to measure various parameters in the data set. More detailed instrument information is provided in the original data set documents found in the references of Section 17. SRC Equipment Single Channel Sensor: This instrument measures photosynthetically active radiation (PAR). Q-6 Net Radiometer: This instrument measures net radiation. Eppley Model PSP Precision Spectral Pyranometers: These instruments measure total incoming shortwave radiation and reflected shortwave radiation. Model HMP35CF Temperature Relative Humidity Probe: This instrument measures above canopy air temperature and relative humidity. Model 107F Temperature Probe: This instrument measures within canopy air temperature. Model 107BAM Temperature Probes: These instruments measure soil temperature. 4000AL Everest Interscience Infrared Thermometer: This instrument measures infrared (canopy radiative) temperature. Setra SBP270 Barometric Pressure Sensor: This instrument measures station pressure. R.M. Young Wind Monitor (Model 05103-10): This instrument measures horizontal wind speed and direction. Belfort Rainfall Transmitter: This instrument measures cumulative precipitation. UDG01 Ultrasonic Depth Gauge: This instrument measures snow depth. Model TE525 Tipping Bucket Rain Gauge: This instrument measures the intensity of rainfall. Eppley Precision Infrared Radiometer (Pyrgeometer) (Model PIR): This instrument measures incoming longwave radiation. Eppley Precision Pyranometer (Model PSP) and Eppley Shadow Band Stand: These instruments measure diffuse shortwave radiation. TF-02 Equipment R.M. Young Model 05103: This instrument measures horizontal wind speed and direction. Eppley Model PSP Precision Spectral Pyranometer: This instrument measures total incoming shortwave radiation. Licor Model LI-190SB: This instrument measures PAR. Net Radiometer Swissteco Model S-1: This instrument measures net radiation. Weathertronics 5124: This instrument measures above canopy air temperature and relative humidity. Setra SBP270 Barometric Pressure Sensor: This instrument measures station pressure. 4000A Everest Interscience Infrared Thermometer: This instrument measures infrared (canopy radiative) temperature. Texas Electronics Tipping Bucket Rain Gauge: This instrument measures the intensity of rainfall. TF-05 Equipment Licor Model LI-190S: This instrument measures PAR. Net Radiometer (Swissteco Model S-1 or Rebs Model 6): These instruments measure net radiation. Campbell Model 207: This instrument measures air temperature. Vaisala, Model HMP-35A: This instrument measures relative humidity. R.M. Young Model 05701: This instrument measures horizontal wind speed and direction. Everest Radiation Thermometer (Model 112C): This instrument measures infrared (canopy radiative) temperature. 4.1.1 Collection Environment Data were collected continuously in all kinds of weather from 01-Jan-1994 through 31-Dec-1996. Missing data in the NSA resulted in the data set beginning 18-Jan-1994 and ending 01-Dec-1996 for the Old Jack Pine (NSA-OJP) site and Thompson airport (NSA-YTH). Sites are located in forested areas of aspen and jack pine. Please refer to Airborne Flux and Meteorology (AFM)-07 SRC Meteorological and Radiation Data Set documentation, Tower Flux (TF)-02 documentation, TF-05 documentation, and TF-01 documentation for more detailed information on data collection. 4.1.2 Source/Platform Data were collected from towers extending from the ground to above canopy height. Instruments were placed on these towers along with the necessary data logging and communication equipment to remotely transfer the data to SRC in Saskatoon. Data were checked every 6 hours for errors. Instrument failure was corrected within several days of detection. Please refer to AFM-07 SRC Meteorological and Radiation Data Set documentation, TF-02 documentation, TF-05 documentation, and TF-01 Documentation for more detailed information on data collection. 4.1.3 Source/Platform Mission Objectives Please refer to the BOREAS AFM-07 SRC Surface Meteorological Data, BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data, BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data, and BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data documents for more detailed information on data collection. 4.1.4 Key Variables YEAR JULIAN DAY DATE TIME ABOVE CANOPY AIR TEMPERATURE WITHIN CANOPY AIR TEMPERATURE STATION PRESSURE RELATIVE HUMIDITY MIXING RATIO U COMPONENT OF WIND V COMPONENT OF WIND PRECIPITATION SNOW DEPTH TOTAL INCOMING SHORTWAVE RADIATION INCOMING PAR REFLECTED SHORTWAVE RADIATION NET RADIATION INFRARED (CANOPY RADIATIVE) TEMPERATURE SOIL TEMPERATURE AT 10CM DEPTH SOIL TEMPERATURE AT 20CM DEPTH SOIL TEMPERATURE AT 50CM DEPTH DIFFUSE INCOMING SHORTWAVE RADIATION INCOMING LONGWAVE RADIATION PARAMETER FLAGS 4.1.5 Principles of Operation Please refer to the BOREAS AFM-07 SRC Surface Meteorological Data, BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data, BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data, and BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data documents for more detailed information on data collection. 4.1.6 Sensor/Instrument Measurement Geometry Please refer to the BOREAS AFM-07 SRC Surface Meteorological Data, BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data, BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data, and BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data documents for more detailed information on data collection. 4.1.7 Manufacturer of Sensor/Instrument Please refer to the BOREAS AFM-07 SRC Surface Meteorological Data, BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data, BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data, and BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data documents for more detailed information on data collection. 4.2 Calibration 4.2.1 Specifications 4.2.1.1 Tolerance Please refer to the BOREAS AFM-07 SRC Surface Meteorological Data, BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data, BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data, and BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data documents for more detailed information on data collection. 4.2.2 Frequency of Calibration Please refer to the BOREAS AFM-07 SRC Surface Meteorological Data, BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data, BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data, and BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data documents for more detailed information on data collection. 4.2.3 Other Calibration Information Please refer to the BOREAS AFM-07 SRC Surface Meteorological Data, BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data, BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data, and BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data documents for more detailed information on data collection. 5. Data Acquisition Methods To begin the compilation of this data set, the required parameters were extracted from the SRC tables in the BOREAS Information System (BORIS) data base into files containing each year of 15-minute data for each of the four sites. Flux tower data from TF-02 and TF-05 were also acquired so that available parameters could be used as substitute data when the SRC data were missing. Snow and precipitation data were also acquired for several days from the AES station at Thompson Airport, Thompson, Manitoba when SRC and TF snow and precipitation data were missing. 6. Observations 6.1 Data Notes There were many gaps in the initially extracted SRC data. When these data gaps lasted less than 2 hours, the missing data were linearly interpolated from bounding values. If data were missing for more than 2 hours, data from that time period were substituted from the other SRC site within that study area if data were available. When data were missing from both sites, data were also linearly interpolated from bounding values since none of the time periods lasted more than several hours. Because precipitation cannot be readily interpolated, all efforts were made to determine precipitation amounts during a period of missing data by using known information. If precipitation was missing for a block of time but the Belfort gauge showed the same amount of precipitation when the site came back online as it showed just before the site went down, it was assumed that no precipitation fell during that period of time (i.e., precipitation values are shown as zero). If Belfort information was not known, precipitation was substituted from the other SRC site within the same study area. Because snow depth varies more from site to site than from day to day, snow may be interpolated while other data have been substituted. This is done to give a more accurate estimation of actual snow depth. The following list shows the data gaps that remained after both interpolation and substitution were performed (All times in Greenwich Mean Time (GMT)): SSA-OA: INFRARED TEMPERATURE 01-JAN-94:0000 to 15-FEB-94:2345 DIFFUSE SHORTWAVE 01-JAN-94:0000 to 18-FEB-94:2015 INCOMING LONGWAVE 01-JAN-94:0000 to 20-JAN-94:2145 ALL PARAMETERS EXCEPT DIFFUSE SHORTWAVE AND INCOMING LONGWAVE 15-JUL-94:1815 to 16-JUL-94:0300 16-JUL-94:1815 to 20-JUL-94:2030 SSA-OJP: INFRARED TEMPERATURE 01-JAN-94:0000 to 15-FEB-94:2345 DIFFUSE SHORTWAVE 01-JAN-94:0000 to 18-FEB-94:2015 INCOMING LONGWAVE 01-JAN-94:0000 to 20-JAN-94:2145 ALL PARAMETERS EXCEPT DIFFUSE SHORTWAVE AND INCOMING LONGWAVE 15-JUL-94:1815 to 16-JUL-94:0300 16-JUL-94:1815 to 20-JUL-94:2030 NSA-OJP: INFRARED TEMPERATURE 18-JAN-94:0000 to 18-FEB-94:2300 PRECIPITATION 19-NOV-94:1000 to 20-NOV-94:1845 SNOW DEPTH 22-NOV-94:2200 to 23-NOV-94:0145 DIFFUSE SHORTWAVE 18-JAN-94:0000 to 27-JAN-94:2345 08-AUG-94:2215 to 22-AUG-94:2200 INCOMING LONGWAVE 08-AUG-94:2215 to 22-AUG-94:2200 NSA-YTH: INFRARED TEMPERATURE 18-JAN-94:0000 to 18-FEB-94:2300 PRECIPITATION 19-NOV-94:1000 to 20-NOV-94:1845 SNOW DEPTH 22-NOV-94:2200 to 23-NOV-94:0145 Due to turnover in staff and loss of information in the creation of this data set, tabulation of the remaining time gaps are not available for 1995 and 1996. 6.2 Field Notes Please refer to Section 6.2 in the AFM-07 SRC Meteorological and Radiation Data Set documentation, TF-02 documentation, TF-05 documentation, and TF-01 documentation. 7. Data Description 7.1 Spatial Characteristics 7.1.1 Spatial Coverage The data in this data set are intended to represent two sites in the NSA and two sites in the SSA. The North American Datum of 1983 (NAD83) corner coordinates of the SSA are: Latitude Longitude -------- --------- Northwest 54.321 N 106.228 W Northeast 54.225 N 104.237 W Southwest 53.515 N 106.321 W Southeast 53.420 N 104.368 W The NAD83 corner coordinates of the NSA are: Latitude Longitude -------- --------- Northwest 56.249 N 98.825 W Northeast 56.083 N 97.234 W Southwest 55.542 N 99.045 W Southeast 55.379 N 97.489 W The NAD83 coordinates of the BOREAS SRC tower sites were: Latitude Longitude -------- --------- SRC SSA-OA 53.628 N 106.196 W SRC SSA-OJP 53.916 N 104.689 W SRC NSA-OJP 55.928 N 98.622 W SRC NSA-YTH 55.804 N 97.874 W Data were substituted from flux tower sites with the following NAD83 coordinates: Latitude Longitude ---------- ----------- SSA-OA 53.62890 N 106.19779 W SSA-OJP 53.91634 N 104.69203 W NSA-OJP 55.92842 N 98.62396 W 7.1.2 Spatial Coverage Map None. 7.1.3 Spatial Resolution The data from the original sites are point values at a given location. The intent of creating a merged data set was for the data to be representative of the SSA or NSA, although the gradients can be observed between the SSA sites and the NSA sites. 7.1.4 Projection Not applicable. 7.1.5 Grid Description Not applicable. 7.2 Temporal Characteristics 7.2.1 Temporal Coverage The data cover the time period of 01-Jan-1994 to 01-Dec-1996. 7.2.2 Temporal Coverage Map Not available. 7.2.3 Temporal Resolution SRC 15-minute averages for all parameters except Belfort precipitation and snow depth. Hourly: BELFORT GAUGE PRECIPITATION (winter only) SNOW DEPTH Although Belfort Precipitation and Snow Depth are measured every hour on the hour, each hour's value is given every 15 minutes. TF-02 30 minute values TF-05 30 minute values 7.3 Data Characteristics Data characteristics are defined in the companion data definition file (srfmetmd.def). 7.4 Sample Data Record Sample data format shown in the companion data definition file (srfmetmd.def). 8. Data Organization 8.1 Data Granularity The smallest unit of data that can be ordered from this data set is a year’s worth of data. 8.2 Data Format(s) The 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 (srfmetmd.def). 9. Data Manipulations 9.1 Formulae The following formulae were required in processing this data set: For RELATIVE HUMIDITY: RH = e / es(T) where RH is relative humidity (percent), e is vapor pressure, and es(T) is saturation vapor pressure e = X * ( R / Mw ) * T where e is vapor pressure (Pa), X is absolute humidity, or vapor density (g m-3), R is the gas constant = 8.314 J mol-1 K-1, Mw is the molecular weight of water = 18 g mol-1, and T is air temperature (K). es(T) = 6.112 * exp[ (17.67 * T) / (T + 243.5)] where es(T) is saturation vapor pressure (mb), and T is air temperature (degrees Celsius) For MIXING RATIO: q = ( 622 * e ) / ( P - e ) where q is mixing ratio (grams/kilogram), e is vapor pressure (mb), and P is station pressure (mb) e = RH * es(T) where e is vapor pressure, RH is relative humidity (percent), and es(T) is saturation vapor pressure es(T) = 6.112 * exp[ ( 17.67 * T ) / ( T + 243.5 )] where es(T) is saturation vapor pressure (mb), and T is air temperature (degrees Celsius) For DIFFUSE INCOMING SHORTWAVE RADIATION: Diffuse Incoming Shortwave / Incoming Shortwave = slope * [ Incoming Shortwave / cosine( zenith angle )] + intercept For INCOMING LONGWAVE RADIATION: Incoming Longwave = Net Radiation + Reflected Shortwave + Outgoing Longwave - Total Incoming Shortwave where Outgoing Longwave is approximated by 5.67E-08 * ( Infrared Temperature )4 which is based on the Stefan-Boltzmann radiation law, assuming an emissivity of 1. 9.1.1 Derivation Techniques and Algorithms As the FORTRAN program linearly interpolated and substituted data (see Section 9.2.1), it flagged the source of each parameter and is included in each file record. The last column in each file shows a string of characters that are the flags. Beginning with the flag for ABOVE CANOPY AIR TEMPERATURE, since this is the first measured parameter, each flag in the string corresponds to a parameter column. There will be the same number of parameter flags as there are parameters--19 for SSA-OA, SSA-OJP, and NSA-OJP, and 17 for NSA-YTH. Following the parameter flags are three precipitation-related flags. The first of these is the PRECIPITATION GAUGE FLAG. A 'T' is shown if precipitation data were measured from the tipping bucket rain gauge. A 'B' is shown if precipitation data were measured from the Belfort weighing precipitation gauge. The tipping bucket gauge cannot measure frozen precipitation, so it is used only in the summer. The next flag is the PRECIPITATION ZEROED FLAG. This place will show either an 'O' for original precipitation data, or a 'Z' if the data have been zeroed. Sometimes when the Belfort gauge is used, a negative precipitation value is obtained. Before processing, the Belfort raw value is cumulative. At each time, the previous cumulative value is subtracted from the current value to obtain the amount of precipitation that has fallen within the last 15 minutes. When this value is negative (because of sensor error), it has been zeroed and flagged with a Z in this flag place to alert the user that actual data are not shown. The last flag is the SNOW DEPTH ZEROED FLAG. Like the Belfort gauge, the snow depth sensor sometimes gives negative values when there is little snow on the ground. This value has been zeroed and will be flagged with a 'Z' in this flag place. At all other times the flag is 'O'. 9.2 Data Processing Sequence 9.2.1 Processing Steps BORIS staff compiled surface meteorological data by: 1) Extracting a year-long file of 15-minute continuous data for each of four chosen BOREAS SRC Meteorological Towers from the BORIS data base. 2) Inputting these files into a FORTRAN program that would linearly interpolate missing parameters when these parameters were missing for less than 2 hours. 3) Inputting the files from step 2 into a FORTRAN program that would compare the files from the two towers within one study area and substitute missing parameters from one file to the other when parameters were missing for more than 2 hours. 4) Using the TF data sets from TF-02 (SSA-OA) and TF-05 (SSA-OJP) to substitute available missing parameters when both sites within the SSA were missing the same parameters. 5) Using Thompson airport precipitation data when SRC data were missing during winter when no flux tower data were available. 6) Using the methods described in Section 9.3.1 to calculate remaining missing parameters to obtain a complete continuous 15-minute data set for an entire year at the four chosen BOREAS SRC sites. 9.2.2 Processing Changes None. 9.3 Calculations 9.3.1 Special Corrections/Adjustments RELATIVE HUMIDITY: The flux tower at SSA-OJP measures absolute humidity. When relative humidity is missing from SRC and is replaced by the value measured at SSA-OJP, the absolute humidity has been converted to relative humidity. The relative humidity value was calculated using the equation RH = e / es(T) (1) where e is vapor pressure and es(T) is saturation vapor pressure. By substituting the following for e in equation (1) e = X * ( R / Mw ) * T (2) the result is: RH(fraction) = X * T /( 2.165 * es(T) ) where e is vapor pressure (Pa), X is absolute humidity, or vapor density (g/m3), R is the gas constant = 8.314 J/(mol K), Mw is the molecular weight of water = 18 g/mol, and T is air temperature (K), can be substituted, as shown in equation 3. But to put vapor pressure in standard units of kiloPascals (kPa), it is necessary to divide (2) by 1000, resulting in RH(fraction) = X * T / ( 2165 * es(T) ) (3) (J.L. Monteith & M.H. Unsworth, 1990). Using the measured air temperature, the saturation vapor pressure is obtained by using the equation es(T) = 6.112 * exp[ ( 17.67 * T ) / ( T + 243.5 )] (4) where here T is air temperature (degrees Celsius) and es(T) is saturation vapor pressure (mb). To put es(T) in standard units of kPa in order to be used with vapor pressure in kPa, divide the equation by 10 to obtain: es(T) = ( 6.112 * exp[ ( 17.67 * T ) / ( T + 243.5 )]) / 10 (5) Now terms for e and es(T) are used to obtain RH(fraction) so that relative humidity is now in terms of air temperature and absolute humidity (both are measured parameters.) Multiply by 100 to obtain percentage. MIXING RATIO: This parameter is not measured but is derived from the measured relative humidity, pressure, and above-canopy air temperature. The following equation is used to determine mixing ratio: q = ( 622 * e ) / ( P - e ) (6) where q is mixing ratio (grams kilogram-1), e is vapor pressure (mb), and P is station pressure in (mb). Substituting e = RH * es(T) (7) into (6) gives q = ( 622 * RH * es(T) ) / ( P - ( RH * es(T) )) (8) where RH is relative humidity (fraction) and es(T) is saturation vapor pressure. Using (4) we can substitute into (8) to form q = 622 * a / ( P - a) (9) where a = RH * 6.112 * exp[ ( 17.67 * T ) / ( T + 243.5 )] Using the property that ( Constant * a ) / ( b - a ) = [( Constant * a ) / ( b - a )] * [1/a] / [1/a] = Constant / ( b / a - 1 ) where Constant = 622 and b = P, we obtain q = 622 / ( P / ( RH * 6.112 * exp [ (17.67 * T ) / ( T + 243.5 )]) - 1) (10) which can be rearranged to form q = 622 / (( .16361 / RH ) * P * exp [ (-17.67 * T ) / ( T + 243.5 )] - 1) (Bolton, 1980). Since three parameters are required to derive mixing ratio, its data source flag is marked according to the source from which at least two of the three parameters came. U COMPONENT OF WIND V COMPONENT OF WIND: Wind speed and wind direction were measured at the SSA-OA and SSA-OJP flux towers. Therefore, it was necessary to convert these parameters to components for the data set using the equations U COMPONENT OF WIND = -(wind speed)*[sine(wind direction from which wind travels)] V COMPONENT OF WIND = -(wind speed)*[cosine(wind direction from which wind travels)] PRECIPITATION: Two precipitation gauges are used. In 1994, a tipping bucket rain gauge was used to measure 15-minute rainfall from 01-MAY-94:0000Z through 31-OCT-94:2345Z at SSA-OA and SSA-OJP, from 16-MAY-94:0000Z through 31-OCT-94:2345Z at NSA-OJP, and from 26-MAY-94:0000Z through 31-OCT-94:2345Z at NSA-YTH. In 1995, a tipping bucket rain gauge was used to measure 15-minute rainfall from 01-MAY-95:0000Z through 31-OCT-95:2345Z at SSA-OA, from 08-MAY-95:0000Z through 31-OCT-95:2345Z at SSA-OJP, from 16-JUN-95:0000Z through 31-OCT-95:2345Z at NSA-OJP, and from 08-MAY-95:1200Z through 31-OCT-95:2345Z at NSA-YTH. At all other times of the year, a Belfort gauge was used to measure cumulative rainfall and cumulative water equivalence of frozen precipitation. There is some error in the Belfort sensor such that the value may oscillate about a point. To get 15-minute precipitation data from the cumulative value, the previous record's value is subtracted from the current value. When the calculated value was negative due to sensor error, the value was zeroed. This is flagged with a Z in the second to last (PRECIPITATION ZEROED) flag column. The usual flags for data source (original (O), interpolated, or substituted) appear in the actual precipitation parameter flag column. SSA data sets were missing precipitation in the summer when this value could be substituted from flux towers. NSA data sets were missing precipitation only in winter when flux towers were not running. For missing precipitation in the NSA sites, precipitation data from the Thompson airport are used. Thompson airport measures water equivalence and ranges of snowfall intensity such as light, moderate, heavy, etc.; therefore, snow depth has been estimated for this time period. For SSA-OA: Data were missing from 17-JUN-95:0615Z through 17-JUN-95:1200Z. All parameters except precipitation were interpolated. The Belfort gauge showed zero at 17- JUN-95:0600Z and 5.4 mm at 17-JUN-95:1215Z, so it was assumed that 5.4 mm of rain fell within that time period. Data from SRC SSA-OJP were also missing. By checking the SRC sites at La Ronge, Meadow Lake, and Saskatoon, an estimate of precipitation was determined. La Ronge and Meadow Lake showed no precipitation, but Saskatoon showed that 0.6 mm fell at 0815Z, 0.2 mm at 0830Z, 0.6 mm at 0845Z, and 2 mm at 0900Z. Assuming it rained at SSA-OA at the same time, the extra 2 mm that fell at SSA-OA was divided among the time periods so that precipitation was set to 1.1 mm at 0815Z, 0.7 mm at 0830Z, 1.1 mm at 0845Z, and 2.5 mm at 0900Z. Precipitation for this time period is flagged with 'P'. Data were missing from 20-JUN-95:0015Z through 20-JUN-95:0600Z. All parameters except precipitation were interpolated. The Belfort gauge showed 27.1 mm at 20- JUN-95:0000Z and 37.7 mm at 20-JUN-95:0615Z. Data from SRC SSA-OJP were also missing. By checking the SRC sites at La Ronge, Meadow Lake, The Pas, and Saskatoon, an estimate of precipitation was determined. La Ronge was also missing. The Pas and Meadow Lake showed no precipitation, but Saskatoon showed 1.2 mm at 0230Z, 0.2 mm at 0315Z, 0.2 mm at 0330Z, 0.8 mm at 0345Z, and 0.2 mm at 0400Z. Data were missing from 22-AUG-95:0615Z through 23-AUG-95:0645. All parameters except precipitation were substituted from SSA-OJP. The Belfort gauge showed 14.1 mm at 22-AUG-95:0600Z and 15.6 mm at 23-AUG-95:0700Z, so it was assumed that 1.5 mm of rain fell within that time period. One mm fell at SSA-OJP at 22- AUG-95:0830Z, and 0.3 mm fell at 0845Z. Since SSA-OA is located west of SSA- OJP, precipitation was set to 1 mm at 22-AUG-95:0730Z, 0.3 mm at 0745Z, and 0.2 mm at 0800Z and flagged with 'P'. Data were missing from 11-JUL-95:0015Z through 12-JUL-95:0200Z. The Belfort gauge showed 59.6 mm at 11-JUL-95:0000Z and 79.1 mm at 12-JUL-95:0215Z. This amount appears to be too great since only 2 mm fell at SSA-OJP during this time period. It was decided to substitute all missing parameters including precipitation from SSA-OJP for this time period. Data were missing from 29-DEC-95:0015Z through 29-DEC-95:0400Z. All parameters were interpolated since data were also missing from SSA-OA at these times. Precipitation values did not change while the site was down, so it was assumed that no precipitation fell at these times. For NSA-OJP: All parameters were missing from 02-FEB-95:1715Z through 22-FEB-95:2330Z. All parameters were substituted since precipitation events could not be determined. All parameters were missing from 23-NOV-95:1900Z through 23-NOV-95:1945Z. All parameters were interpolated except precipitation. The Belfort gauge showed 101.38 mm at 1845Z and 105.78 mm at 2000Z. It was decided to divide this 4.4 mm evenly by recording 1.1 mm at 1900Z, 1915Z, 1930Z, and 1945Z. Precipitation and snow depth were missing 28-NOV-95 at 0230Z and 0245Z. Both values were the same at 0215Z and 0300Z so it was determined that no precipitation occurred. All data were missing 29-DEC-95:0015Z through 29-DEC-95:0345Z. All parameters were interpolated, but Belfort values were the same, so it was determined that no precipitation occurred. For NSA-YTH: All parameters were missing from 23-JUN-95:1215Z through 23-JUN-95:1700Z. All parameters were substituted except precipitation. The Belfort value did not change so it was assumed that precipitation did not occur. All parameters except radiation were missing from 17-AUG-95:1930Z through 13-OCT-95:1900Z. All parameters were substituted since it was not possible to determine precipitation events. Precipitation was missing from 23-NOV-95:1730Z through 24-NOV-95:0000Z. The Belfort value did not change so it was determined that no precipitation occurred. All parameters were missing from 29-DEC-95:0015 through 29-DEC-95:0345Z. The Belfort value did not change so it was determined that no precipitation occurred. SNOW DEPTH: Snow depth was not measured during the summer months and is shown as '0'. When there was very little snow on the ground, the sensor gave sporadic negative values. For this data set, these values have been set to zero and flagged with a Z in the last (SNOW DEPTH ZEROED) flag column. The usual flags for data source (original (O), interpolated, or substituted) appear in the actual snow depth parameter flag column. REFLECTED SHORTWAVE RADIATION: This parameter was not measured at flux towers. When SRC data are missing, all other radiation components have been substituted from flux towers. This parameter is then calculated as a residual using Reflected Shortwave = Total Incoming Shortwave + Incoming Longwave - Outgoing Longwave - Net Radiation where Outgoing Longwave is approximated by 5.67E-08 * (Infrared Temperature)4 which is based on the Stefan-Boltzmann radiation law, assuming an emissivity of 1. SOIL TEMPERATURE AT 10-CM DEPTH SOIL TEMPERATURE AT 20-CM DEPTH SOIL TEMPERATURE AT 50-CM DEPTH: Soil temperatures at these depths were not measured at the flux towers. These parameters are missing from 15-JUL-94:1815Z through 20-JUL-94:2030Z at SSA-OA and SSA-OJP. Values for each time step have been linearly interpolated such that values at 14-JUL-94:1815Z and 21-JUL-94:1815 are used to interpolate 15-JUL-94:1815, 16-JUL-94:1815, 17-JUL-94:1815, 18-JUL-94:1815, 19-JUL-94:1815, 20-JUL-94:1815, and so on through every 15-minute block of each missing day. These values are flagged with M to denote this time-step type of linear interpolation. Near the end of the missing data period at SSA-OJP, a straight linear interpolation is performed between 21-JUL-94:1815 and 21-JUL-94:2030 to smooth the data. This is flagged with the usual L. DIFFUSE INCOMING SHORTWAVE RADIATION: This parameter was not measured at the NSA-YTH site. Missing periods for SSA- OA, SSA-OJP, and NSA-OJP cannot be substituted from TF sites as this parameter was not measured at flux towers. In 1994, diffuse incoming shortwave was missing at NSA-OJP from 18-JAN-94:0000Z to 27-JAN-94:2345 and 08-AUG-94:2215Z to 22-AUG-94:2200Z, and at SSA-OA and SSA-OJP from 01-JAN-94:0000Z to 18-FEB- 94:2015Z. In 1995, diffuse incoming shortwave was missing at NSA-OJP from 06- MAY-95:1815Z to 08-MAY-95:0330Z, from 27-MAY-95:1815Z to 29-MAY-95:0045Z, and from 23-NOV-95:1815Z to 11-DEC-95:0400Z. For NSA-OJP: Using Total Incoming Shortwave Radiation, Diffuse Incoming Shortwave Radiation, and zenith angle from the missing time periods, Total Incoming Shortwave / Diffuse Incoming Shortwave, or the diffuse fraction, was plotted versus Incoming Shortwave / [ cosine( zenith angle )]. This has a near linear relationship when zenith angles between 40 and 90 degrees are used. Only values of Incoming Shortwave / [ cosine( zenith angle )] between 200 and 1200 were used as this eliminated wide scatter. Regression was performed to obtain a linear equation from the plot. For these particular cases, the following equations were obtained: for 28-JAN-94:0000Z to 06-FEB-94:0000Z: Diffuse Incoming Shortwave / Incoming Shortwave = -0.00042 * Incoming Shortwave / cosine( zenith angle ) + 1.001453 for 29-JUL-94:0000Z to 08-AUG-94:2200Z: Diffuse Incoming Shortwave / Incoming Shortwave = -0.00077 * Incoming Shortwave / cosine( zenith angle ) + 0.989878 for 23-NOV-95:1815Z to 11-DEC-95:0400Z: Diffuse Incoming Shortwave / Incoming Shortwave = -0.00079 * Incoming Shortwave / cosine( zenith angle ) + 1.129367 These equations were used for the missing time periods to calculate DIFFUSE INCOMING SHORTWAVE RADIATION using known values of TOTAL INCOMING SHORTWAVE RADIATION. When a value of DIFFUSE INCOMING SHORTWAVE RADIATION greater than TOTAL INCOMING SHORTWAVE RADIATION was calculated, it was set equal to TOTAL INCOMING SHORTWAVE RADIATION. For SSA-OA: This site has substituted TOTAL INCOMING SHORTWAVE from SSA-OJP from 01-JAN- 94:0000Z to 10-JAN-94:1400, from 11-JAN-94:0330Z to 20-JAN-94:2230Z, and from 18-FEB-94:2030Z to 22-FEB-94:0045Z. At these times, the derived DIFFUSE INCOMING SHORTWAVE RADIATION has also been substituted from SSA-OJP for consistency. Using Total Incoming Shortwave Radiation, Diffuse Incoming Shortwave Radiation, and zenith angle from 22-FEB-94:0100Z to 01-MAR-94:2345Z (since these time periods are available at this site), Total Incoming Shortwave / Diffuse Incoming Shortwave, or the diffuse fraction, was plotted versus Incoming Shortwave / [ cosine( zenith angle )]. This has a near linear relationship when zenith angles between 40 and 90 degrees are used. Only values of Incoming Shortwave / [ cosine( zenith angle )] between 200 and 1200 were used as this eliminated wide scatter. Regression was performed to obtain a linear equation from the plot. For this particular case, the equation Diffuse Incoming Shortwave / Incoming Shortwave = -0.00096 * Incoming Shortwave / cosine( zenith angle ) + 1.323676 was obtained. This equation was used for the missing time periods to calculate DIFFUSE INCOMING SHORTWAVE RADIATION using known values of TOTAL INCOMING SHORTWAVE RADIATION. When a value of DIFFUSE INCOMING SHORTWAVE RADIATION greater than TOTAL INCOMING SHORTWAVE RADIATION was calculated, it was set equal to TOTAL INCOMING SHORTWAVE RADIATION. For SSA-OJP: Using Total Incoming Shortwave Radiation, Diffuse Incoming Shortwave Radiation, and zenith angle from 18-FEB-94:2030Z to 28-FEB-94:2030Z, Total Incoming Shortwave / Diffuse Incoming Shortwave, or the diffuse fraction, was plotted versus Incoming Shortwave / [ cosine( zenith angle )]. This has a near linear relationship when zenith angles between 40 degrees and 90 degrees are used. Only values of Incoming Shortwave / [ cosine( zenith angle )] between 200 and 1200 were used as this eliminated wide scatter. Regression was performed to obtain a linear equation from the plot. For this particular case, the equation Diffuse Incoming Shortwave / Incoming Shortwave = -0.00094 * Incoming Shortwave / cosine( zenith angle ) + 1.328154 was obtained. This equation was used for the missing time periods to calculate DIFFUSE INCOMING SHORTWAVE RADIATION using known values of TOTAL INCOMING SHORTWAVE RADIATION. When a value of DIFFUSE INCOMING SHORTWAVE RADIATION greater than TOTAL INCOMING SHORTWAVE RADIATION was calculated, it was set equal to TOTAL INCOMING SHORTWAVE RADIATION. INCOMING LONGWAVE RADIATION: This parameter was not measured at the NSA-YTH site. Missing periods cannot be substituted from TF sites as this parameter was not measured at flux towers. Incoming Longwave was missing at NSA-OJP from 08-AUG-94:2215Z to 22-AUG-94:2200Z, and at SSA-OA and SSA-OJP from 01-JAN-94:0000Z to 20-JAN- 94:2145Z. For these missing periods, Incoming Longwave was calculated as a residual using Incoming Longwave = Net Radiation + Reflected Shortwave + Outgoing Longwave - Total Incoming Shortwave where Outgoing Longwave is approximated by 5.67E-08 * (Infrared Temperature)4 INTERPOLATION OF TF DATA: TF data at SSA-OA and SSA-OJP were measured only at half-hour intervals (on the hour and half past the hour). Therefore it was necessary to interpolate the values at 15 and 45 minutes past the hour so that these data sets could be merged with the SRC data sets when SRC data were missing. It should be understood that the values at 15 and 45 minutes past the hour are interpolated. They will be flagged with the usual 'A' or 'J' for substitution from SSA-OA flux tower or SSA-OJP flux tower, respectively. Only when a block of data is missing (for less than 2 hours) from a flux tower and is linearly interpolated will the 'C' or 'K' be used for interpolation of SSA-OA flux tower data or SSA-OJP flux tower data, respectively. 9.3.2 Calculated Variables Variables calculated for entire data set: MIXING RATIO Variables calculated for portions of the data set: RELATIVE HUMIDITY REFLECTED SHORTWAVE RADIATION DIFFUSE INCOMING SHORTWAVE RADIATION INCOMING LONGWAVE RADIATION U COMPONENT OF WIND V COMPONENT OF WIND 9.4 Graphs and Plots None. 10. Errors 10.1 Sources of Error STATION PRESSURE: This parameter has been flagged with a '?' from 01-JAN-94:0000Z to 19-FEB-94:0130Z at SSA-OA, 01-JAN-94:0000Z to 19-FEB-94:0230Z at SSA-OJP, 18-JAN-94:0000Z to 1994 19-FEB-94:0330Z at NSA-OJP, and 18-JAN-94:0000Z to 18-FEB-94:2245Z at NSA-YTH. Values at these times are incorrect and cannot be retroactively corrected. Please use these values only to evaluate pressure trends. 10.2 Quality Assessment 10.2.1 Data Validation by Source Please refer to the BOREAS AFM-07 SRC Surface Meteorological Data, BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data, BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data, and the BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data documentation for more detailed information on data collection. 10.2.2 Confidence Level/Accuracy Judgment Please refer to this section in the AFM-07 SRC Surface Meteorological Data, BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data, BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data, and BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data documents for original data confidence. Parameters were measured at various heights, which affects accuracy (see Section 11.2). It was felt that a linear interpolation of parameters missing for less than 2 hours was a good approximation of actual values. When substituting from one SRC tower to another, subtle differences in instrument height, elevation, terrain, canopy, current weather conditions, and other various factors cause the substituted data to be less accurate than actual data. The degree of accuracy depends on these numerous qualitative factors. Reflected Shortwave and Incoming Longwave are sometimes calculated as residuals assuming Net Radiation is the balance of Total Incoming Shortwave, Incoming Longwave, Reflected Shortwave, and Outgoing Longwave. Obviously this neglects other factors and sensor errors that either add to or subtract from this balance. Diffuse Incoming Shortwave is sometimes calculated from a regression equation relating Diffuse Incoming Shortwave, Total Incoming Shortwave, and zenith angle. It was very difficult to assess the accuracy of this method since no measurements of cloud cover were made by any of the data sources. 10.2.3 Measurement Error for Parameters Please refer to the documentation for the following data sets for more detailed information: BOREAS AFM-07 SRC Surface Meteorological Data BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data 10.2.4 Additional Quality Assessments Please refer to the documentation for the following data sets for more detailed information: BOREAS AFM-07 SRC Surface Meteorological Data BOREAS TF-01 SSA-OA Tower Flux and Meteorological Data BOREAS TF-02 SSA-OA Tower Flux and Meteorological Data BOREAS TF-05 SSA-OJP Tower Flux and Meteorological Data 10.2.5 Data Verification by Data Center The data were spot checked for accuracy. 11. Notes 11.1 Limitations of the Data These data were compiled to provide a consistent modeling data set over a long period of time (i.e., years) for a group of modelers in the BOREAS project. Since some of the data were interpolated or substituted from various sources, caution should be taken in using this data set, especially when trying to make inferences over short time periods. 11.2 Known Problems with the Data Please note that substituted data will have been measured at a different height than the original data. The height difference depends on parameter and data source. This affects the accuracy of the data but is still a good approximation since height differences were not large. Please refer to the equipment sections (Section 4) of the following documents for sensor heights: BOREAS AFM-07 SRC Surface Meteorological Data BOREAS TF-05 Tower Flux and Meteorological Data BOREAS TF-02 Meteorological Data Set at Southern Study Area Old Aspen site (SSA- OA) WITHIN CANOPY AIR TEMPERATURE: When this variable is missing from both SRC towers within a study area for more than 2 hours, it cannot be replaced by other means since it was not measured at a flux tower. A '-999' is given in place of a value. A good approximation of this value would be the Infrared (Canopy Radiative) Temperature. INFRARED (CANOPY RADIATIVE) TEMPERATURE: When this variable is missing from SRC for more than 2 hours during winter, it cannot be replaced by other means since flux towers were not collecting data in winter. A '-999' is given in place of a value. A good approximation of this value would be the within canopy air temperature. STATION PRESSURE: This parameter has been flagged with a '?' from 01-JAN-94:0000Z to 19-FEB-94:0130Z at SSA-OA, 01-JAN-94:0000Z to 19-FEB-94:0230Z at SSA-OJP, 18-JAN-94:0000Z to 1994 19-FEB-94:0330Z at NSA-OJP, and 18-JAN-94:0000Z to 18-FEB-94:2245Z at NSA-YTH. Values at these times are incorrect and cannot be retroactively corrected. Please use these values only to evaluate pressure trends. PRECIPITATION: When the Belfort gauge is used, as mentioned in Section 9.3.1, values sometimes oscillate about a point. The raw value is cumulative so that in order to obtain 15-minute values, the last period's value must be subtracted from the current value. If the current value is less than that of the last period, the value will be set to zero. If the current value is greater than that of the last period, the positive difference will be given. If this value is small, it may not be due to a precipitation event. The user must use his or her judgment to determine which values denote actual precipitation and which denote sensor noise. From analysis, it appears that values of 0.1 denote sensor noise. 11.3 Usage Guidance This data set was compiled as a consistent standard data set for BOREAS modelers to use in climate and weather models. Because data were interpolated and substituted to fill data gaps, caution should be used when trying to draw inferences from this data set. 11.4 Other Relevant Information None. 12. Application of the Data Set This data set was compiled as a consistent standard data set for BOREAS modelers to use in process models. Because data were interpolated and substituted to fill data gaps, caution should be used when trying to draw inferences from this data set. 13. Future Modifications and Plans None. 14. Software 14.1 Software Description BORIS staff developed a set of FORTRAN programs to process and merge the existing data into the form presented here. The software modules and their functions are: LINTERP.FOR - Perform needed linear interpolation of data for gaps two hours or less in duration within a given file. SUBST.FOR - Compares the contents of two input files and substitutes data from one to the other to fill in data gaps. 14.2 Software Access The software is available from the ORNL DAAC. See section 15 for details. 15. Data Access 15.1 Contact Information Ms. Beth Nelson NASA GSFC Greenbelt, MD (301) 286-4005 (301) 286-0239 (fax) Elizabeth.Nelson@gsfc.nasa.gov 15.2 Data Center Identification See 15.1. 15.3 Procedures for Obtaining Data Users may place requests by telephone, electronic mail, or FAX. 15.4 Data Center Status/Plans These data are available from the EOSDIS ORNL DAAC (Earth Observing System Data and Information System) (Oak Ridge National Laboratory) (Distributed Active Archive Center). The BOREAS contact at ORNL is: ORNL DAAC User Services Oak Ridge National Laboratory (865) 241-3952 ornldaac@ornl.gov ornl@eos.nasa.gov 16. Output Products and Availability 16.1 Tape Products None. 16.2 Film Products None. 16.3 Other Products Tabular ASCII data files. 17. References 17.1 Platform/Sensor/Instrument/Data Processing Documentation Please refer to this section in the AFM-7 SRC Meteorological and Radiation Data Set documentation, TF-02 Documentation, TF-05 Documentation, and TF-01 Documentation. 17.2 Journal Articles and Study Reports Please refer to this section in the AFM-7 SRC Meteorological and Radiation Data Set Documentation, TF-02 Documentation, TF-05 Documentation, and TF-01 Documentation. Bolton, D., 1980. The Computation of Equivalent Potential Temperature. Monthly Weather Review, 108:1046-1053. Monteith, J.L. and M.H. Unsworth. 1990. Principles of Environmental Physics. Edward Arnold, New York. Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94). 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., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC 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. 1997. Boreal Ecosystem-Atmosphere Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96). 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 (JGR), BOREAS Special Issue, 102(D24), Dec. 1997, pp. 28731-28770. 17.3 Archive/DBMS Usage Documentation None. 18. Glossary of Terms e - vapor pressure es(T) - saturation vapor pressure (function of T) Mw - molecular weight of water = 18 g/mol P - station pressure q - mixing ratio R - gas constant = 8.314 J/(mol K) RH - relative humidity T - air temperature at approximately 10 meters above the canopy X - absolute humidity or vapor density -999 - given when parameter is missing Units: g - grams J - Joules K - Kelvin kPa - kiloPascals m - meters mb - millibars mol - mole Pa - Pascals 19. List of Acronyms AFM - Aircraft Flux and Meteorology (BOREAS Science Group) ARC - Ames Research Center AES - Atmospheric Environment Service ASCII - American Standard Code for Information Interchange BOREAS - BOReal Ecosystem-Atmosphere Study BORIS - BOREAS Information System CCRS - Canada Centre for Remote Sensing CCT - Computer Compatible Tape CD-ROM - Compact Disk-Read-Only Memory DAAC - Distributed Active Archive Center DAT - Digital Archive Tape EOS - Earth Observing System EOSDIS - EOS Data and Information System GMT - Greenwich Mean Time GSFC - Goddard Space Flight Center HTML - Hypertext Markup Language MARSII - Meteorological Automatic Reporting System II NAD83 - North American Datum of 1983 NASA - National Aeronautics and Space Administration NSA - Northern Study Area OA - Old Aspen OJP - Old Jack Pine ORNL - Oak Ridge National Laboratory PAR - Photosynthetically Active Radiation READAC - Remote Environmental Automatic Data Acquisition Concept SRC - Saskatchewan Research Council (AFM-07) SSA - Southern Study Area TF - Tower Flux (BOREAS Science Group) URL - Uniform Resource Locator YTH - Thompson Airport 20. Document Information 20.1 Document Revision Date Written: 21-March-1996 Last Updated: 09-Dec-1998 20.2 Document Review Date(s) BORIS Review: 26-Oct-1998 Science Review: 20.3 Document ID 20.4 Citation The BOREAS derived surface meteorological data were compiled by BORIS personnel at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC). Their contributions to providing this data set are greatly appreciated. 20.5 Document Curator 20.6 Document URL Keywords Surface meteorology Temperature Precipitation Pressure Wind speed Wind direction Modeled_Surf_Met.doc 01/13/99