DRAFT
JULY 1996
There are three types of systems within the ARM/CART region that measure vertical profiles of temperature within the boundary layer, rawinsondes, Radio Acoustic Sounding Systems (RASS), and the Atmospheric Emitted Radiance Interferometer (AERI). The only rawinsonde stations within the ARM/CART domain are those from the Department of Energy (DOE) ARM program and the National Weather Service (NWS). The ARM rawinsondes routinely collect temperature observations at a vertical resolution of 2-sec. Soundings will be released 5 times each weekday at the central facility (6, 12, 15, 18, and 21 UTC) and once each weekday at each of the four boundary facilities (18 UTC) during regular operations (see Figure 3-9 for ARM facility locations). During IOPs (e.g. April 1996) soundings are released every three hours, seven days a week, at all five facilities. The NWS has one rawinsonde location within the ARM/CART domain at Norman, OK. The NWS provides 6-sec vertical resolution observations at two release times (00 and 12 UTC). Occasionally more frequent releases occur at the request of the NWS.
The RASS are collocated with some of the wind profiler systems within the ARM/CART domain (see Figure 3-17). Two facilities (Purcell, OK and Haviland, KS) already have RASS and two others (Vici and Morris, OK) will have them by June 1996. The Lamont, OK profiler site will not have a RASS unit. RASS allows for the calculation of vertical profiles of virtual temperature at 250 m vertical resolution every 6 min. The ARM program operates two RASS units at their central facility.
The AERI unit is located at the ARM central facility (see Figure 3-9) and measures infrared radiation yielding radiance spectra which are transformed to vertical temperature and water vapor profiles. Profiles are generated every 10 minutes.
Water vapor profiles are obtained from the rawinsonde and AERI systems described above at the same temporal and vertical resolutions as for the temperature.
Wind profiles are from the ARM rawinsondes (described above) at 10-sec vertical resolution and the NWS rawinsondes at 6-sec vertical resolution.
The NOAA Profiler Network provides 6-min and hourly observations of the wind profiles at a vertical resolution of 250 m.
The WSR-88D Doppler radars record velocity spectra information in the Level II archive as well as velocity products in the Level III archive. GCIP will use the Level III wind data products only. There are no plans to include wind data products from the Level II archive.
The ASOS provides 1, 5, or 60 min observations of ceiling and cloud heights up to 12,000 feet at 20 stations within the ARM/CART domain. The AWOS provides similar observations at 20-min intervals at two stations and 5-min intervals at one station within the ARM/CART domain. The SAOs provide hourly and occasional special observations of ceiling and cloud heights and amounts with no upper limit on the observational height at 13 locations within the ARM/CART domain.
Several systems provide measurements of each of these parameters. The ASOS provide 1, 5, or 60 min observations at 20 stations within the ARM/CART domain. The AWOS provide 20-min observations at 2 stations and 5-min observations at one station within the ARM/CART domain. The SAOs provide hourly and occasional special observations at 13 stations within the ARM/CART domain. The High Plains Climate Network provides hourly observations at 6 locations within the ARM/CART domain. The Oklahoma Mesonet provides 5-min observations at 48 stations within the ARM/CART domain. The NOAA Profiler Network provides 6-min observations at its 5 locations within the ARM/CART domain. The DOE ARM/CART provides surface data from its extended facilities (see Figure 3-9). Data from 15 of the 26 proposed ARM/CART extended facilities should be available. The 45- station ARS Little Washita Watershed Micronet provides 15 min observations of temperature and relative humidity. Three of the Micronet stations also provide wind speed, wind direction, and barometric pressure at 15 min intervals.
The NOAA/GEWEX long term flux monitoring site, operated by Tilden Meyers (NOAA/ARL), located in the Little Washita Watershed provides measurements of temperature and humidity.
The humidity variables collected from each system (typically dew point) can be converted into specific humidity.
OFPS will also develop hourly and 5-min composites of the data from these observing systems. The 5-min composites will include data only from those sites that routinely archive data at 5-min or higher frequencies. No special data collections are planned for ESOP-96 unlike for GIST and ESOP-95.
The ARM program Eddy Correlation (ECOR) systems provide measurements of surface momentum flux within the ARM/CART domain. These are planned to be operating at nine of the ARM/CART extended facilities over wheat and other crops (see Figure 3-10).
The NOAA/GEWEX long term flux monitoring site provides measurements of surface momentum flux in the Little Washita Watershed.
Two systems within the ARM domain provide measurements of the surface heat flux. The ECOR system mentioned above and the Energy Balance Bowen Ratio (EBBR) system. The EBBR systems are planned to be at 11 extended facilities over pasture and rangeland, all but one (at the central facility) of which are located at the extended facilities which do not have the ECOR system (see Figure 3-10).
Also, the NOAA/GEWEX long term flux monitoring site provides measurements of the sensible and latent heat fluxes in the Little Washita Watershed.
The soil heat flux to the surface is provided by the EBBR system.
The skin temperature is derived from measurements provided by the SIROS (Solar and Infrared Radiation Observing System) upwelling hemispherical irradiances at 18 of the ARM/CART extended facilities (including the central facility).
The NOAA/GEWEX long term flux monitoring site also provides measurements of the skin temperature.
Observations of precipitation are collected from each of the station varieties mentioned in section 2.1 at the same observational frequencies. Additional precipitation observations come from the NWS Cooperative observers at either 15-min or hourly frequency, the 45 station ARS Micronet provides 15-min precipitation observations, the Arkansas-Red Basin River Forecast Center (ABRFC) collects data at 15-min (approximately 45 stations within the ARM/CART domain), hourly (approximately 95 stations), or with no set schedule (approximately 135 stations), the US Army Corps of Engineers (USACE) collects hourly observations and the USGS collects daily observations for a total of approximately 115 stations within the ARM/CART domain. The NOAA/GEWEX long term flux monitoring site also provides precipitation measurements in the Little Washita Watershed. OFPS also will develop 15-min and hourly composites of precipitation from all of the observing systems.
The NEXRAD Information Dissemination Service (NIDS) 1-hr surface rainfall accumulation product will be archived by OFPS. This is a one hour running total of surface rainfall accumulation. The resolution is 2 km by 2 km and the range is 230 km. This product will be archived from nine radars near the ARM/CART domain (see Figure 3-18).
The ABRFC routinely produces an hourly composite derived precipitation product from all WSR-88D radars covering the Arkansas-Red River basins. These data are on a 4 km by 4 km grid.
The ARM/CART SIROS provides measurements of up and down welling hemispherical solar irradiances, direct-beam solar irradiance, diffuse hemispherical solar irradiance from the sky and up- and downwelling hemispherical infrared irradiances via its collection of instruments including the Multifilter Rotating Shadowband Radiometer (MFRSR), pyranometer, pyrheliometer, and pyrgeometer at 19 of the ARM extended facilities (including the central facility).
The 45 ARS Micronet stations provide measurements of incoming solar radiation.
A MultiFilter Radiometer (MFR) at the central facility provides measurements of upwelling radiation at 10 m.
The AERI system provides measurements of infrared radiances at zenith at the central facility.
A 60-m tower at the central facility provides upwelling hemispheric infrared irradiance measurements as well as upwelling hemispherical solar radiation measurements from 25 m using a pyranometer, pyrgeometer and an MFR.
The ARM Broadband Solar Radiation Network (BSRN) at the central facility provides measurements of infrared (pyrgeometer) and solar (pyranometer) irradiances as well as direct solar irradiance (pyrheliometer) and direct, diffuse, and total solar irradiances at six selected wave bands and a wide band (MFRSR).
Also at the central facility is a pyrometer at 10 m that measures 10 micron upwelling radiation and a similar instrument at 25 m elevation over a wheat field.
The NOAA/GEWEX long term flux monitoring site also provides measurements of net radiation, incoming and outgoing Photosynthetically Active Radiation (PAR) and infrared irradiances in the Little Washita Watershed.
Observations of streamflow within the ARM/CART domain are available from the US Army Corps of Engineers (USACE) and the USGS from a total of about 130 sites within the ARM/CART domain.
The USGS collects daily observations of reservoir capacity for nine reservoirs within the ARM/CART domain.
Available USGS well water height data from the area around the ARM/CART domain will be collected.
Some of the NWS Cooperative observer network sites collect daily observations of evaporation. There are 207 cooperative observation locations within the ARM/CART domain a subset of which collect evaporation measurements.
Satellite derived values of the Normalized Difference Vegetation Index (NDVI) are routinely produced at the EROS Data Center (EDC) at Sioux Falls, SD. One set of NDVI data is made available bi-weekly. The land cover imagery will be produced bi-weekly from 1 km resolution Advanced Very High Resolution Radiometer (AVHRR) and translated to GIF by the USGS EDC. The full land characteristics data files will then be published on CD-ROM by EDC. The GIF imagery will serve as the browse for the full data base during this time.
This will start with the generally provided station list information provided by OFPS and be augmented with a list of measurements made at each station. The typically provided information includes site identifiers (3-4 letter ids, site names), type of instrumentation (i.e. ASOS etc.), frequency of observation, latitude, longitude, elevation, and beginning and end dates of operation.
For point measurements this should include soils, vegetation type, surrounding geophysical features (ponds, lakes, rivers, pavement, forest, etc.).
A detailed description will be cataloged for each of the sites which have the soil moisture and soil temperature profile sensor systems operating during this initial phase. The detailed description of the other sites will be postponed until the second data collection phase.
An extensive array of soil moisture sensor systems are being installed in the ARM/CART site, Little Washita Watershed, and the Oklahoma Mesonet over the next two years. Installation plans for these sensor systems at more than 100 locations are now being implemented. We shall distinguish the shallow (< 10 cm) from the deep (> 50 cm) profile measurements.
Deep Soil Moisture Profiles: Seven locations in the ARM/CART site and at least six locations in the Little Washita Watershed will be operating during the course of the ESOP-96 from April through September 1996. The Campbell Scientific Heat Dissipation Soil Moisture Sensor (Model 229-L) is the sensor system of choice for this composite network. This newly developed sensor measures water potential by heating a needle embedded in a porous ceramic cylinder, and then observing the temperature change of the cylinder itself, which is linearly related to the amount of water permeating the porous cylinder. Since this is a new sensor system, its ability to provide soil moisture measurements in an operational environment needs to be validated.
The ARM/CART sensors are being installed at eight different depths: 5, 15, 25, 35, 60, 85, 125, and 175 cm unless bedrock is reached prior to the lower depths. Each site will have two profiles located one meter apart. Eight site locations are scheduled to be operating by the start of ESOP-96 on 1 April 1996.
The Little Washita Watershed sensors are being installed at six different depths: 5 (3 sensors), 10, 15 , 20, 25, and 60 cm. The three sensors at 5 cm are installed 10 cm apart. Five site locations are installed as of 3/11/96 with an additional five planned to be installed by 5/96. The deepest level of 60 cm is expected to be near the lowest level of the rooting zone in the Little Washita Watershed.
The Oklahoma Mesonet has installed one sensor system at Norman, OK as a test facility. Additional sensor systems are to be delivered by mid April with initial installation starting in May. Some soil moisture profiles are expected during the latter half of ESOP-96. Each location will have four probes per site with depths from 5 cm to 50 cm.
Shallow Soil Moisture Profiles: The 10 Energy Balance Bowen Ratio (EBBR) flux stations in the ARM/CART site are equipped to provide soil moisture in the 3 to 5 cm range at five points around each flux station. These provide information for correcting the thermal conductivity of the soil so the soil heat fluxes can be determined. The accuracy of these measurements may not be sufficient for some model evaluation purposes.
Soil temperature profiles or subsurface heat flux profiles are being measured in the ARM/CART, Little Washita micronetwork, and Oklahoma mesonetwork. We shall distinguish between deep (>50 cm) and shallow (<10 cm) temperature profile measurements.
Deep Temperature Profiles: The Campbell Scientific Heat Dissipation Soil Moisture Sensor (Model 229L) provides soil temperature at the same eight levels as the soil moisture in the ARM/CART network: 5, 15, 25, 35, 60, 85, 125, and 175 cm. Each site will have two profiles locations spaced about one meter apart.
Three sensor systems at each of the Little Washita sites will provide either soil temperature or heat flux measurements:
* Campbell Scientific 229L at the same depths as the soil moisture given above, i.e. 5, 10,
15, 20, 25, and 60 cm.
* Campbell 107B Soil thermistors at the depths of 2.5, 5, 10, 15, 20, 25, 60, and 100 cm.
* Rebs HFT-3 Heat flux plates at the depths of 5, 25, and 60 cm.
Note: The Campbell Scientific Model 229L will also need to be validated for soil temperature in an operational environment as noted above for soil moisture.
Shallow Temperature Profiles: The 10 Energy Balance Bowen Ratio (EBBR) flux stations in the ARM/CART site are equipped to provide soil temperature (average 0 to 5 cm) at five points around each flux station.
Some of the NWS Cooperative observer network sites collect daily observations of soil temperature. There are 207 cooperative observation locations within the ARM/CART domain a subset of which collect evaporation measurements.
Soil physical and hydraulic properties for the Near-Surface Observing Period will be available from two sources: field observation and spatial datasets derived from USDA/NRCS National Cooperative Soil Survey Databases.
Field Observation - Observations based on soil core analysis at the soil moisture monitoring sites for soil moisture. This will be a combination of profile descriptions and laboratory soil characterization in Little Washita Watershed, ARM/CART site, and the Oklahoma Mesonet.
There are also existing soils databases for at least portions of this region, e.g. the ARS at Durant, OK has a relatively detailed soils database for the Little Washita Watershed.
Digital soils information derived from the USDA-NRCS State Soil Geographic Database (STATSGO) and the Soil Survey Database (SSURGO) will provide spatially distributed soils data for the ARM/CART area. GCIP will use the 1-km Multi-Layer Soil Characteristics Dataset developed by D. Miller at Penn State's Earth System Science Center. This dataset, developed from the STATSGO database, covers the 48 conterminous United States at a resolution of 1-km and contains soil physical and hydraulic properties including: texture, depth-to-bedrock, particle size distribution, rock fragment class and volume, porosity, hydrologic soil groups, and available water capacity. Details on the dataset may be found on the WWW at the following URL:
http://www.essc.psu.edu/soil_info/
The point at which the vegetation can no longer access the minimum amount of soil moisture needed to survive. It is dependent on the type of vegetation to a great extent. The ARM/CART and Little Washita sites are mainly concerned with wheat, pasture, rangeland, and forest as vegetation types. Observational data for the different types of vegetation in the ARM/CART site and the Little Washita Watershed will be provided in this dataset.
This variable is interpreted as the depth to which roots penetrate the soil and this is vegetation type dependent. Observations will be available from the sites where the soil moisture profile sensors are being installed. Observations from six locations in the ARM/CART site place the rooting zone in the range of 45 to 60 cm.
NOTE: This was listed as one of the parameters needed in setting up an experiment in land process modeling. Based on comments received we include the following statement: It's really not a measurable quantity and, due to hysterisis may not always be the same for the same soil. Within Variable 3.3 Soil Physical and Hydraulic Properties, there is a value of "available water capacity". This is essentially the volume of water that would be available to plants if the soil, exclusive of rock fragments, were at field capacity. It is expressed both as a volume fraction and as a thickness of water in the profile.