Overview
In anticipation of NASA’s Global Precipitation Measurement (GPM) ground-validation activities in the SE United States and synergies with NOAA’s Hydrometeorology Testbed-Southeast Pilot Study (HMT-SEPS), under the auspices of the Integrated Precipitation and Hydrology Experiment ( IPHEx ), a high-resolution data set is being developed to provide the Hydrologic Modeling/Forecasting for the Southeast ( IPHEx -H4SE) with common control forcing and landscape attributes to facilitate multi-scale, multi-purpose hydrologic modeling studies ranging from flash-flood forecasting to basin-scale water resource assessments. In the first phase of the project, the goal is to generate quality hydrometeorological forcing data sets at high spatial and temporal resolution (1km×1km, hourly time step) for the five-year time period 2007-2011 with a focus on the river basins with headwaters in the Southern Appalachians: Upper Tennessee River Basin (56,573 km 2 ), Savannah River Basin (27,110 km 2 ), Santee River Basin (39,862 km 2 ) and Yadkin-Pee Dee River Basin (46,310 km 2 ), as shown in Figure 1. Table 1 summarizes the databases produced in this project. Overall, the databases include soil hydraulic parameters derived from the State Soil Geographic (STATSGO) database, landscape attributes datasets derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) products, atmospheric forcing data derived from the North American Regional Reanalysis (NARR), and precipitation generated from NCEP/EMC 4KM Gridded Data (GRIB) Stage IV datasets. All the datasets were extracted from the original data source, reprojected to UTM17N (WGS84) and bi-linearly interpolated to the domain grid system at 1km (Figure 1). Then, correction and adjustment were applied to improve these datasets, aiming to provide the five-year “historical” best states, which are essential for many applications such as hydrological hindcasts/forecasts, evaluating model skills and uncertainty, and testing impacts of hydrometeorology regimes (e.g. missing light rainfall or warmer nights).
Description of the Datasets
Soil hydraulic parameters (i.e. saturated hydraulic conductivity, porosity, field capacity and wilting point) were extracted in ArcGIS from the STATSGO database. The values of the vertical top 11 standard soil layers in STATSGO are provided. Space-time varying land surface properties such as broadband albedo, broadband emissivity, fractional vegetation coverage, and leaf area index were derived from MODIS products. The original products are re-projected and composited to the study area, bi-linearly interpolated to basin grids, and then linearly interpolated into hourly time steps. Quality-control and temporal filtering for the landscape attributes data are performed to reduce the discontinuity caused by cloud contamination. The atmospheric forcing data are extracted from North American Regional Reanalysis (NARR) products originally at 32-km spatial resolution and 3-hour temporal resolution. Elevation adjustments and corrections to near-surface variables are applied between NARR envelope terrain and local terrain at every time-step based on predicted atmospheric conditions (e.g. using dynamic lapse rates). Special bias corrections for downward shortwave radiation are applied through dynamical adjustment, accounting for localized elevation and topographic effects. The temporal interpolation for shortwave radiation is integrated in the topographic correction to capture the local diurnal solar cycle based on solar zenith angle. Precipitation is generated from NCEP/EMC 4KM Gridded Data (GRIB) Stage IV hourly data using the bi-linear interpolation method. Integration of Stage IV data with precipitation observations from research networks in the region provides dynamic relationships for improving precipitation accuracy in mountainous terrain.
Time-invariant Datasets
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MODIS Landcover: landcover (IGBP type and UMD type) from MODIS yearly product MCD12Q1.
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Soil Parameters: saturated hydraulic conductivity, porosity, field capacity and wilting point extracted from the STATSGO database.
All the time-invariant datasets are provided in ascii files. Please see here for the general description of the geographic information about these ascii files.
Time-variant Datasets
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Precipitation: hourly precipitation extracted and generated from StageIV product.
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Atmospheric Forcing Datasets: air temperature, air pressure, specific humidity, wind speed, incoming shortwave and longwave radiation extracted from NARR and adjusted for elevation and topographic effects.
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Landscape Attributes Datasets: land surface broadband emissivity and albedo, leaf area index and fractional vegetation coverage extracted/derived from MODIS products and temporally filtered for cloud contamination.
All the time-variant datasets are provided in binary files. Please see here for a description of data format and sample codes for reading the binary files.
Table - Summary of the Datasets (N=Row number, M=Column number, T=Time Steps)
|
Data Category
(Source)
|
Variable Name
|
Data Filename
|
SIZE
|
FORMAT
|
Unit
|
|
Soil Parameters
(STATSGO)
|
Saturated hydraulic conductivity
|
HydroCond.txt
|
N×M
|
ASCII
|
m/s
|
|
Porosity
|
Poro.txt
|
N×M
|
ASCII
|
m 3 /m 3
|
|
Field capacity
|
FieldCapa.txt
|
N×M
|
ASCII
|
m 3 /m 3
|
|
Wilting point
|
WiltPot.txt
|
N×M
|
ASCII
|
m 3 /m 3
|
|
Landscape Attributes
(MODIS)
|
Albedo
|
Albedo.bin
|
N×M×T
|
BIN
|
-
|
|
Emissivity
|
Emissivity.bin
|
N×M×T
|
BIN
|
-
|
|
Fractional vegetation coverage
|
CV.bin
|
N×M×T
|
BIN
|
-
|
|
Leaf area index
|
LAI.bin
|
N×M×T
|
BIN
|
-
|
|
Atmospheric Forcing Data
(NARR)
|
Specific humidity at 10m ABG
|
SpecHumi_10m.bin
|
N×M×T
|
BIN
|
kg/kg
|
|
Air temperature at 10m ABG
|
AirTemp_10m.bin
|
N×M×T
|
BIN
|
K
|
|
Air pressure at 10m ABG
|
AirPressure_10m.bin
|
N×M×T
|
BIN
|
mb
|
|
Wind velocity at 10m ABG
|
WindSpeed_10m.bin
|
N×M×T
|
BIN
|
m/s
|
|
Incoming longwave radiation at surface
|
DLWR_surf.bin
|
N×M×T
|
BIN
|
W/m 2
|
|
Incoming shortwave radiation at surface
|
DSWR_surf.bin
|
N×M×T
|
BIN
|
W/m 2
|
|
Precipitation
(Stage IV)
|
Precipitation
|
Precip_StageIV_Bi.bin Precip_StageIV_TF.bin Precip_StageIV_TF_GC.bin
|
N×M×T
|
BIN
|
mm at top-of-hour
|
