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Description

The Princeton University MEaSUREs Potential Evapotranspiration (PET) dataset provides a set of estimates of PET based on near surface meteorology and surface radiation data derived from a combination of reanalysis, satellite and gridded gauge data. The rationale of the project is to reduce the error from the input meteorological forcing and provide a variety of widely-used PET methods for different research and application purposes.

PET is estimated using three methods: Penman open-water method (Penman), Priestley-Taylor method (PT), Reference crop evapotranspiration using the UN Food and Agricultural Organization approach (FAO). The Penman equation assumes PET occurs from an open water surface and calculates PET based on observations of surface net radiation, near-surface air temperature, wind speed, and specific humidity (Shuttleworth, 1993). The PT equation calculates PET based on surface net radiation and near-surface air temperature and does not account for the aerodynamic component (Priestley and Taylor, 1972). The FAO equation is a specific application of the Penman-Monteith equation for crop and short-grass reference surfaces and is based on surface net radiation, near-surface air temperature, wind speed, and specific humidity (Allen, 1998).

This first version of dataset is estimated at a 3 hourly temporal resolution and 0.25x0.25 degrees spatial resolution globally, spanning the 23-year period 1984-2006. Datasets are stored as a 3-dimensional array with dimension 720 x 1440 x 8 for each day, in NetCDF-4 format.

Version Description

This is the version 1 of PET_PU_3H025, containing 11 variables. This global dataset is based on the Penman, PT, and FAO equations spanning the 23-year period 1984-2006. The dataset uses satellite radiation data from the NASA/GEWEX Surface Radiation Budget (SRB) and meteorology from the Princeton Global Forcing dataset (Sheffield et al., 2006), which is updated to version 3 (PGF-V3). The ground heat flux is based on the dataset produced in Siemann et al. (2018).

Product Summary

Platforms
RM-OBS/PU
Instruments
NOT APPLICABLE
Spatial Extent

N: 90 S: -60 E: 180 W: -180

Geographic Region
GLOBAL LAND
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
1984-01-01 to 2006-12-31
Data Partner
Goddard Earth Sciences Data and Information Services Center (formerly Goddard DAAC), Terrestrial Information Systems Laboratory, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/TISL/GESDI
Concept ID
C1575363595-GES_DISC
Data State
COMPLETE
Number of Files/Granules
8401
Processing Level
4
Published
Updated
Science Keywords
Surface Pressure ,
Heat Flux ,
Net Radiation ,
Surface Temperature ,
Specific Humidity ,
Potential Evapotranspiration ,
Wind Speed

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Sheffield, J. (2018). RM-OBS/PU Potential Evapotranspiration and Supporting Forcing L4 3-hourly 0.25x0.25 degree V001 [Data set]. NASA Goddard Earth Sciences Data and Information Services Center. https://doi.org/10.5067/GPZDZYELYG1A Date Accessed: 2025-12-15

Documents

READ-ME

Variables

Variables are a set of physical properties whose values determine the characteristics or behavior of something. For example, temperature and pressure are variables of the atmosphere. Parameters and variables can be used interchangeably. Variable level attributes provide individual information for each variable.

The Name in this table is the variable name. Fill value indicates missing or undefined data points in a variable. Valid range is the range of values the variable can store. Scale factor is used to increase or decrease the size of an object and can be used to correct for distortion. For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
gflag gflag - float32 -999000000 N/A N/A
ghflx ghflx W/m2 float32 -999000000 N/A N/A
lat lat degrees_north float64 N/A N/A N/A
lon lon degrees_east float64 N/A N/A N/A
petpen petpen mm float32 -999000000 N/A N/A
petpt petpt mm float32 -999000000 N/A N/A
petref petref mm float32 -999000000 N/A N/A
pres pres Pa float32 -999000000 N/A N/A
rflag rflag - float32 -999000000 N/A N/A
rnet rnet W/m2 float32 -999000000 N/A N/A
shum shum kg/kg float32 -999000000 N/A N/A
tas tas Kelvin float32 -999000000 N/A N/A
time time minutes since 1984-09-08 00:00 float64 N/A N/A N/A
wind wind m/s float32 -999000000 N/A N/A
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