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This data set contains meteorological observations at 36 sites throughout the Small Regional Study Area (SRSA) of the NASA Cold Land Processes Field Experiment (CLPX) in Colorado, USA. Identical meteorological towers were located close to the four corners of nine 1 km x 1 km Intensive Study Areas (ISAs). At each site, measurements of air temperature, relative humidity, wind speed, and wind direction were made at 2 m (North Park) or 4 m (Fraser and Buffalo Pass) above ground level. Snow depth, soil moisture, and soil temperatures were also measured. Hourly meteorological observations were recorded between 20 September 2002 and 1 October 2003, although data were not necessarily continuous throughout this time period for all towers.
The NASA CLPX is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km^2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry; and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.
We kindly request that you cite the use of this data set in a publication using the following citation example. For more information, see our Use and Copyright Web page.
Houser, P. and D. Kunera. 2005. CLPX-Ground: ISA Corner Site Meteorological Data. [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center.
|Data format||Comma-delimited ASCII|
|Spatial coverage and resolution||Meso-cell Study Areas (MSAs) within the CLPX SRSA, northern Colorado|
|Temporal coverage and resolution||20 September 2002 to 1 October 2003, with 1-hour temporal resolution|
|File size||1 KB for header files to 1.3 MB for data files|
|Parameter(s)||Wind speed, wind direction, air temperature, relative humidity, snow depth, soil moisture, soil temperature|
|Procedures for obtaining data||Data are available via FTP. Access data|
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Thirty-six identical meteorological towers were located close to each corner of nine CLPX Intensive Study Areas (ISAs). At each site, measurements of air temperature, relative humidity, wind speed, and wind direction were made at either 2 m or 4 m above ground level. Snow depth, soil moisture, and soil temperatures were also measured. Meteorological observations were recorded at an hourly resolution between September 2002 and October 2003.
In addition to direct observations, parameters were generated within the logger program and as a result of post processing (year, month, day, hour and minute [HH:MM], and decimal day of year [Deci-DOY]). All time measurements were recorded in Greenwich Mean Time (GMT).
Each tower collected the following 22 specific parameters:
HHMM [hour and minute]
Deci-DOY (decimal day of year)
Air Temperature [1-hr average] (°C)
Air Temperature [1-hr maximum] (°C)
Air Temperature [1-hr minimum] (°C)
Relative humidity [1-hr average] (%)
Relative humidity [1-hr maximum] (%)
Relative humidity [1-hr minimum] (%)
Wind speed [1-hr average] (ms-1)
Wind speed [1-hr maximum] (ms-1)
Wind speed [1-hr minimum] (ms-1)
Wind direction [1-hr average] (degrees)
Acoustic depth sounder (m)
Average hydraprobe temperature: 5 cm (°C)
Average hydraprobe soil water content: 5 cm (water fraction by volume, wfv)
Average hydraprobe temperature: 20 cm (°C)
Average hydraprobe soil water content: 20 cm (wfv)
Average hydraprobe temperature: 50 cm (°C)
Average hydraprobe soil water content: 50 cm (wfv)
12:00 midnight on day 100 is 100.0
6:00 a.m. on day 100 is 100.25
12:00 noon on day 100 is 100.5
6:00 p.m. on day 100 is 100.75
In addition, the data include photographs of the meteorological towers and surroundings. For each tower, there are six associated photographs: one of the tower, one looking down, and one looking from the tower in each compass direction.
Meteorological data are presented in comma-delimited ASCII format. Each data file contains 22 parameters (columns), which are listed above, in consecutive 1-hour time intervals. Column header information for each data file is provided in a separate comma-delimited ASCII file (Headers.csv).
Data for each of the corner sites is contained in one file; the files are named as follows:
"##" refers to the two- or three-letter MSA, ISA code:
NM = North Park, Michigan River
NI = North Park, Illinois River
NP = North Park, Potter Creek
RB = Rabbit Ears, Buffalo Pass
RS = Rabbit Ears, Spring Creek
RW = Rabbit Ears, Walton Creek
FS = Fraser, St. Louis Creek
FF = Fraser, Fool Creek
FA = Fraser, Alpine
"$$" refers to the ISA corner:
NE = Northeast Corner
SE = Southeast Corner
NW = Northwest Corner
SW = Southwest Corner
Headers are not included in the first row of each data file. A separate file containing header information is provided, named Headers.csv.
A separate directory ("photos") contains photographs of the meteorlogical towers and the surrounding areas. There are six photographs associated with each tower: one of the tower, one looking down, and one looking from the tower in each compass direction. Photographs are named accordingly; for example, "FANE.JPG" is the photograph of the FANE site tower; "FANE-Down.JPG" is the downward-looking photograph; and "FANE-East.JPG" is the photograph looking eastward from the FANE site tower.
The uncompressed meteorological files range from 0.08 MB to 1.3 MB.
Spatial coverage consists of the three MSAs within the SRSA (105° to 107.5° W, 39.5° to 41° N). One measurement tower was placed at, or close to, the corner of each ISA. Exact locations of each 2-m or 4-m high instrument tower are as follows:
|Site ID||UTM (Easting)||UTM (Northing)||Latitude||Longitude||Elevation (m)|
|RBSE||358076||4487891||40.530||-106.675||elevation data missing|
Data are Universal Transverse Mercator (UTM) projection: Zone 13 North, based on the WGS84 datum.
The following map shows the CLPX study area:
Meteorological data were collected between September 2002 and October 2003; data are not continuous at all sites throughout this period.
Measurements of all parameters were made every 10 seconds. For all parameters except snow depth, soil moisture content and soil temperature, measurements were averaged over every 1-hour period. For snow depth, soil moisture content, and soil temperature, no average was taken and instead a single sample measurement was recorded at the mid-point of each 1-hour period.
Parameters presented in this data set are wind speed, wind direction, air temperature, relative humidity, snow depth, soil moisture, and soil temperature.
|Parameter||Minimum Value||Maximum Value|
|Air temperature (°C)||-50||50|
|Relative humidity (%)||0||105|
|Wind speed (ms-1)||0||50|
|Average hydraprobe temperature: 5 cm (°C)||-50||50|
|Average hydraprobe soil water content: 5 cm (wfv)||0||0.7|
|Average hydraprobe temperature: 20 cm (°C)||-50||50|
|Average hydraprobe soil water content: 20 cm (wfv)||0||0.7|
|Average hydraprobe temperature: 50 cm (°C)||-50||50|
|Average hydraprobe soil water content: 50 cm (wfv)||0||0.7|
Data that were considered suspect during manual filtering were left in Level 1 files even after they were identified as suspect. This was done when technicians recognized potential inconsistencies but were either unsure of the cause or were unable to verify their assumptions. Rather than alter the data set without definitive proof of faulty data, data were left for further interpretation and quality control by future investigators. Although the investigator has a high level of confidence in the products that are delivered in this data set, future investigators should implement their own quality control procedures.
The available data product has been processed to a Level 1 standard. This means that raw data (Level 0 data), which were downloaded on approximately a 6-month basis, have been concatenated into one continuous file per meteorological tower. Data have then been filtered twice for faulty values. The first filtering process was done manually to recognize instrument, wiring, or programming problems. The second filtering process was done computationally to remove blank values or any faulty values that fall outside of acceptable boundaries for each instrument (see table below for instrument list). Faulty data and missing data were replaced with a default value of 8999.
Data are available via FTP. Access data
Photos are available via FTP. Access photos
|Air temperature||Vaisala HMP45C Temperature and Relative Humidity Probe|
|Relative humidity||Vaisala HMP45C Temperature and Relative Humidity Probe|
|Wind speed||MetOne 034A Wind Monitor|
|Wind direction||MetOne 034A Wind Monitor|
|Snow depth||Judd Ultrasonic Depth Sensor|
|Average hydraprobe soil temperature||Stevens Vitel Hydra Soil Moisture Probe|
|Average hydraprobe soil water content||Stevens Vitel Hydra Soil Moisture Probe|
Below are photographs of the wind monitor (top) and snow depth sensor (bottom):
Future investigators should use manufacturers' guidelines to calculate instrument error. No independent instrument calibration has been applied to these data.
A schematic illustrates the assembly of each meteorological tower. Observations were made along a cross-arm of the meteorological tower, at 2 m above the ground surface at the North Park MSA and 4 m above ground surface at all other sites. However, because of sloping ground beneath the cross-arms, these heights should only be considered as approximate values.
The data include six photographs associated with each tower: one of the tower, one looking down, and one looking from the tower in each compass direction. Photographs are named accordingly; for example, "FANE.JPG" is the photograph of the FANE site tower; "FANE-Down.JPG" is the downward-looking photograph; and "FANE-East.JPG" is the photograph looking eastward from the FANE site tower.
|Measurement Location on Tower||Parameters|
|Cross-arm (2 m to 4 m above ground surface)||Wind speed, wind direction, snow depth, air temperature, relative humidity|
|At 5 cm, 20 cm, and 50 cm beneath ground surface||Soil moisture content, soil temperature|
In addition to direct observations, some parameters were generated within
the logger program and as a result of post processing (year, month, day,
HH:MM, and Deci-DOY). All
time measurements were recorded in GMT.
The following acronyms and abbreviations are used in this document.
|CLPX||NASA Cold Land Processes Field Experiment|
|DOY||Day of Year|
|IOP||Intensive Observation Period|
|ISA||Intensive Study Area|
|FTP||File Transfer Protocol|
|GMT||Greenwich Mean Time|
|LRSA||Large Regional Study Area|
|MSA||Meso-cell Study Area|
|SRSA||Small Regional Study Area|
|WFV||Water Fraction by Volume|
27 June 2005