NLDAS Primary Forcing Data L4 Hourly 0.125 x 0.125 degree V002 (NLDAS_FORA0125_H) at GES DISCEntry ID: GES_DISC_NLDAS_FORA0125_H_V002
Abstract: This data set contains the primary forcing data "File A" for Phase 2 of
the North American Land Data Assimilation System (NLDAS-2). The data
are in 1/8th degree grid spacing and range from Jan 1979 to the present.
The temporal resolution is hourly. The file format is WMO GRIB-1.
Details about the generation of the NLDAS-2 forcing data sets can be
found in Xia et al. (2012).
The ... non-precipitation land surface forcing fields for NLDAS-2 are
derived from the analysis fields of the NCEP North American Regional
Reanalysis (NARR). NARR analysis fields are 32-km spatial resolution
and 3-hourly temporal frequency. Those NARR fields that are utilized to
generate NLDAS-2 forcing fields are spatially interpolated to the finer
resolution of the NLDAS 1/8th-degree grid and then temporally
disaggregated to the NLDAS hourly frequency. Additionally, the fields
of surface pressure, surface downward longwave radiation, near-surface
air temperature, and near-surface specific humidity are adjusted
vertically to account for the vertical difference between the NARR and
NLDAS fields of terrain height. This vertical adjustment applies the
traditional vertical lapse rate of 6.5 K/km for air temperature. The
details of the spatial interpolation, temporal disaggregation, and
vertical adjustment are those employed in NLDAS-1, as presented by
Cosgrove et al. (2003).
The surface downward shortwave radiation field in "File A" is a
bias-corrected field wherein a bias-correction algorithm was applied to
the NARR surface downward shortwave radiation. This bias correction
utilizes five years (1996-2000) of the hourly 1/8th-degree GOES-based
surface downward shortwave radiation fields derived by Pinker et
al. (2003). The potential evaporation field in "File A" is that
computed in NARR using the modified Penman scheme of Mahrt and Ek (1984).
The precipitation field in "File A" is not the NARR precipitation
forcing, but is rather a product of a temporal disaggregation of a
gauge-only CPC analysis of daily precipitation, performed directly on
the NLDAS grid and including an orographic adjustment based on the
widely-applied PRISM climatology. The precipitation is temporally
disaggregated into hourly fields by deriving hourly disaggregation
weights from either WSR-88D Doppler radar-based precipitation estimates,
8-km CMORPH hourly precipitation analyses, or NARR-simulated
precipitation (based on availability, in order). The latter fields from
radar, CMORPH, and NARR are used only to derive disaggregation weights
and do not change the daily total precipitation. The field in "File A"
that gives the fraction of total precipitation that is convective is an
estimate derived from the following two NARR precipitation fields (which
are provided in "File B"): NARR total precipitation and NARR convective
precipitation (the latter is less than or equal to the NARR total
precipitation and can be zero). The Convective Available Potential
Energy (CAPE) is the final variable in the forcing data set, also
interpolated from NARR.
The hourly land surface forcing fields for NLDAS-2 are grouped into two
GRIB files, "File A" and "File B". "File A" is the primary (default)
forcing file and contains eleven fields. 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.
61:APCPsfc:Precipitation hourly total [kg/m^2]
157:CAPE180_0mb:180-0 mb above ground Convective Available Potential Energy [J/kg]
153:CONVfracsfc:Fraction of total precipitation that is convective [unitless]
205:DLWRFsfc:Longwave radiation flux downwards (surface) [W/m^2]
204:DSWRFsfc:Shortwave radiation flux downwards (surface) [W/m^2]
228:PEVAPsfc:Potential evaporation [kg/m^2]
1:PRESsfc:Surface pressure [Pa]
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
(Click for Interactive Map)
Start Date: 1979-09-01Stop Date: 1989-03-31
Quality Dates provided in temporal coverage are approximate only.
This record has been completed by staff at the Australian Antarctic Data Centre, and the quality of it's contents and related data cannot be guaranteed.
Access Constraints A pdf copy of the referenced paper is available for download from the provided URL.
Use Constraints This data set conforms to the PICCCBY Attribution License
Please follow instructions listed in the citation reference at the provided URL when using these data.
Data Set Progress
Distribution Media: HTTP
Distribution Size: 1,473 kb
Distribution Format: pdf
Role: TECHNICAL CONTACT
Role: DIF AUTHOR
Phone: +61 3 9905 2929
Fax: +61 3 9905 2948
Email: jim.peterson at arts.monash.edu.au
DEPT OF GEOGRAPHY AND ENVIRONMENTAL SCIENCE MONASH UNIVERSITY WELLINGTON ROAD
Province or State: Victoria
Postal Code: 3168
Role: TECHNICAL CONTACT
Phone: +61 3 6226 2205
Fax: +61 3 6226 2989
Email: jenny.scott at utas.edu.au
SCHOOL OF GEOGRAPHY AND ENVIRONMENTAL STUDIES University of Tasmania PRIVATE BAG 78
Province or State: Tasmania
Postal Code: 7001
Peterson J.A., Scott J.J. (1988) Interrelationships between wind exposure, vegetation distribution and pollen fallout between Bauer Bay and Sandy Bay, Macquarie Island. Papers and Proceedings of the Royal Society of Tasmania 122(1). 247-253
Creation and Review Dates
DIF Creation Date: 2000-07-20
Last DIF Revision Date: 2010-07-20