NLDAS Forcing Data L4 Hourly 0.125 x 0.125 degree V001 (NLDAS_FOR0125_H) at GES DISCEntry ID: GES_DISC_NLDAS_FOR0125_H_V001
Abstract: This data set contains the forcing data for Phase 1 of the North
American Land Data Assimilation System (NLDAS-1). The data are in
1/8th degree grid spacing and range from 29 Sep 1996 to 31 Dec 2007.
The temporal resolution is hourly. The file format is WMO GRIB-1.
The chief source of NLDAS-1 forcing is ... NCEP's Eta model-based Data
Assimilation System (EDAS) [Rogers et al., 1995], a continuously cycled
North American 4DDA system. It utilizes 3-hourly analysis-forecast
cycles to derive atmospheric states by assimilating many types of
observations, including station observations of surface pressure and
screen-level atmospheric temperature, humidity, and U and V wind
components. EDAS 3-hourly fields of the latter five variables plus
surface downward shortwave and longwave radiation and total and
convective precipitation are provided on a 40-km grid, and then
interpolated spatially to the NLDAS grid and temporally to one hour.
Last, to account for NLDAS versus EDAS surface-elevation differences, a
terrain-height adjustment is applied to the air temperature and surface
pressure using a standard lapse rate (6.5 K/km), then to specific
humidity (keeping original relative humidity) and downward longwave
radiation (for new air temperature, specific humidity). The details
of the spatial interpolation, temporal disaggregation, and vertical
adjustment are presented by Cosgrove et al. (2003).
GOES-based solar insolation (Pinker et al., 2003) provides the primary
insolation forcing (shorwave down at the surface) for NLDAS-1. GOES
insolation is not retrieved for zenith angles below 75 degrees and so is
supplemented with EDAS insolation near the day/night terminator. Last
from the GOES-based product suite, Photosynthetically Active Radiation
(PAR) and surface brightness temperature fields are included in the
NLDAS-1 forcing files.
NLDAS-1 precipitation forcing over CONUS is anchored to NCEP's 1/4th
degree gauge-only daily precipitation analyses of Higgins et al. .
In NLDAS-1, this daily analysis is interpolated to 1/8th degree, then
temporally disaggregated to hourly values by applying hourly weights
derived from hourly, 4-km, radar-based (WSR-88D) precipitation fields.
The latter radar-based fields are used only to derive disaggregation
weights and do not change the daily total precipitation. Last,
convective precipitation is estimated by multiplying NLDAS-1 total
precipitation by the ratio of EDAS convective to EDAS total
precipitation. The Convective Available Potential Energy (CAPE) is the
final variable in the forcing dataset, also interpolated from EDAS.
The data set applies a user-defined parameter table to indicate the
contents and parameter number. The following table shows a list of
parameters, their Product Definition Section (PDS) IDs and units.
63:ACPCPsfc:Convective precipitation hourly total [kg/m^2]
61:APCPsfc:Precipitation hourly total [kg/m^2]
118:BRTMPsfc:Surface brightness temperature from GOES-UMD Pinker [K]
157:CAPEsfc:Convective Available Potential Energy [J/kg]
205:DLWRFsfc:Longwave radiation flux downwards (surface) [W/m^2]
204:DSWRFsfc:Shortwave radiation flux downwards (surface) [W/m^2]
101:PARsfc:PAR Photosynthetically Active Radiation from GOES-UMD Pinker [W/m^2]
201:PEDASsfc:Precipitation hourly total from EDAS [kg/m^2]
202:PRDARsfc:Precipitation hourly total from StageII [kg/m^2]
1:PRESsfc:Surface pressure [Pa]
206:RGOESsfc:Shortwave radiation flux downwards (surface) from GOES-UMD Pinker [W/m^2]
51:SPFH2m:2-m above ground Specific humidity [kg/kg]
11:TMP2m:2-m above ground Temperature [K]
33:UGRD10m:10-m above ground Zonal wind speed [m/s]
34:VGRD10m:10-m above ground Meridional wind speed [m/s]
WGRIB or other GRIB reader is required to read the files.
For more information, please see: http://ldas.gsfc.nasa.gov/faq/#Tools
Parameters contained in the data files include the following:
63|ACPCPsfc|Convective precipitation monthly total from EDAS|(kg/m^2)
153|CONVAPCPsfc|Convective precipitation monthly total|(kg/m^2)
61|APCPsfc|Precipitation monthly total|(kg/m^2)
118|BRTMPsfc|Surface brightness temperature from GOES-UMD Pinker|(K)
157|CAPEsfc|Convective Available Potential Energy|(J/kg)
205|DLWRFsfc|Longwave radiation flux downwards (surface)|(W/m^2)
204|DSWRFsfc|Shortwave radiation flux downwards (surface)|(W/m^2)
101|PARsfc|PAR Photosynthetically Active Radiation from GOES-UMD Pinker|(W/m^2)
201|PEDASsfc|Precipitation monthly total from EDAS|(kg/m^2)
202|PRDARsfc|Precipitation monthly total from StageII|(kg/m^2)
206|RGOESsfc|Shortwave radiation flux downwards (surface) from GOES-UMD Pinker|(W/m^2)
51|SPFH2m|2-m above ground Specific humidity|(kg/kg)
11|TMP2m|2-m above ground Temperature|(K)
33|UGRD10m|10-m above ground Zonal wind speed|(m/s)
34|VGRD10m|10-m above ground Meridional wind speed|(m/s)
209|RSWRFsfc|Shortwave radiation flux downwards (surface) blended from EDAS and GOES-UMD Pinker|(W/m^2)
End of parameter information
Data Set Citation
Dataset Originator/Creator: Hydrological Sciences Laboratory at NASA/Goddard Space Flight Center (GSFC/HSL)
Dataset Title: NLDAS Forcing Data L4 Hourly 0.125 x 0.125 degree
Dataset Release Date: 08.01.2009
Dataset Release Place: Greenbelt, Maryland, USA
Dataset Publisher: Goddard Earth Sciences Data and Information Services Center (GES DISC)
Version: 001Online Resource: http://disc.sci.gsfc.nasa.gov/hydrology/index.shtml
Start Date: 1996-08-01Stop Date: 2007-12-31
Latitude Resolution: 0.125 degree
Longitude Resolution: 0.125 degree
Horizontal Resolution Range: 10 km - < 50 km or approximately .09 degree - < .5 degree
Temporal Resolution: hr
Temporal Resolution Range: Hourly - < Daily
ATMOSPHERE > ATMOSPHERIC PRESSURE > SURFACE PRESSURE
ATMOSPHERE > ATMOSPHERIC TEMPERATURE > SURFACE AIR TEMPERATURE
ATMOSPHERE > ATMOSPHERIC WATER VAPOR > HUMIDITY
ATMOSPHERE > ATMOSPHERIC WINDS > CONVECTION
ATMOSPHERE > ATMOSPHERIC WINDS > SURFACE WINDS
ATMOSPHERE > PRECIPITATION > RAIN
ATMOSPHERE > ATMOSPHERIC RADIATION > LONGWAVE RADIATION
ATMOSPHERE > ATMOSPHERIC RADIATION > SHORTWAVE RADIATION
BIOSPHERE > VEGETATION > PHOTOSYNTHETICALLY ACTIVE RADIATION
SPECTRAL/ENGINEERING > INFRARED WAVELENGTHS > BRIGHTNESS TEMPERATURE
ISO Topic Category
Quality The data are provisional and subject to change as model improvements are implemented and new input data sets become available.
Access Constraints None
Use Constraints None
Data Set Progress
Distribution Media: Online (HTTP)
Distribution Format: GRIB
Fees: No Fee
Role: TECHNICAL CONTACT
Email: gsfc-help-disc at lists.nasa.gov
Goddard Earth Sciences Data and Information Services Center Code 610.2 NASA Goddard Space Flight Center
Province or State: MD
Postal Code: 20771
Cosgrove, B. A., D. Lohmann, K. E. Mitchell, P. R. Houser, E. F. Wood, J. Schaake, A. Robock, C. Marshall, J. Sheffield, L. Luo, Q. Duan, R. T. Pinker, J. D. Tarpley, R. W. Higgins, and J. Meng (2003), Real-time and retrospective forcing in the North American Land Data Assimilation System (NLDAS) project, J. Geophys. Res., 108(D22), 8842, doi:10.1029/2002JD003118.
Higgins, ... R. W., W. Shi, E. Yarosh, and R. Joyce (2000), Improved United States precipitation quality control system and analysis, NCEP/Clim. Predict. Cent. Atlas 7, Clim. Predict. Cent., Camp Springs, Md.
Pinker, R. T., J. D. Tarpley, I. Laszlo, K. E. Mitchell, P. R. Houser, E. F. Wood, J. C. Schaake, A. Robock, D. Lohmann, B. A. Cosgrove, J. Sheffield, Q. Duan, L. Luo, and R. W. Higgins (2003), Surface radiation budgets in support of the GEWEX Continental-Scale International Project (GCIP) and the GEWEX Americas Prediction Project (GAPP), including the North American Land Data Assimilation System (NLDAS) project, J. Geophys. Res., 108(D22), 8844, doi:10.1029/2002JD003301.
Rogers, E., D. Deaven and G. J. DiMego, 1995: The regional analysis system for the operational "early" Eta model: original 80-km configuration and recent changes. Wea. Forecasting, 10, 810-825.
Extended Metadata Properties
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Creation and Review Dates
DIF Creation Date: 2009-06-03
Last DIF Revision Date: 2013-08-30