OpenET PT-JPL Monthly Evapotranspiration v2.0

  • The OpenET PT-JPL Monthly Evapotranspiration v2.0 dataset, provided by OpenET, Inc., offers monthly evapotranspiration data from 1999 to the present.

  • This dataset utilizes the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model with enhancements for contemporary weather data, open water evaporation, and advection in arid environments.

  • Key inputs for the model include Landsat surface reflectance and thermal radiation, along with NLDAS, Spatial CIMIS, and gridMET weather data.

  • The dataset contains two bands: 'et' for the PT-JPL ET value in mm and 'count' for the number of cloud-free values.

  • The dataset has a spatial resolution of 30 meters and is available under the CC-BY-4.0 terms of use.
OpenET/PTJPL/CONUS/GRIDMET/MONTHLY/v2_0
Dataset Availability
1999-10-01T00:00:00Z–2024-12-01T00:00:00Z
Dataset Provider
Earth Engine Snippet
ee.ImageCollection("OpenET/PTJPL/CONUS/GRIDMET/MONTHLY/v2_0")
Cadence
1 Month
Tags
evapotranspiration gridmet-derived landsat-derived monthly openet water water-vapor

Description

Priestley-Taylor Jet Propulsion Laboratory (PT-JPL)

The core formulation of the PT-JPL model within the OpenET framework has not changed from the original formulation detailed in Fisher et al. (2008). However, enhancements and updates to model inputs and time integration for PT-JPL were made to take advantage of contemporary gridded weather datasets, provide consistency with other models, improve open water evaporation estimates, and account for advection over crop and wetland areas in semiarid and arid environments. These changes include the use of Landsat surface reflectance and thermal radiation for calculating net radiation, photosynthetically active radiation, plant canopy and moisture variables, and use of NLDAS, Spatial CIMIS, and gridMET weather data for estimating insolation and ASCE reference ET. Similar to the implementation of other OpenET models, estimation of daily and monthly time integrated ET is based on the fraction of ASCE reference ET. Open water evaporation is estimated following a surface energy balance approach of Abdelrady et al. (2016) that is specific for water bodies by accounting for water heat flux as opposed to soil heat flux.

Additional information

Bands

Pixel Size
30 meters

Bands

Name Units Pixel Size Description
et mm meters

PT-JPL ET value
count count meters

Number of cloud free values

Image Properties

Image Properties

Name Type Description
build_date STRING

Date assets were built
cloud_cover_max DOUBLE

Maximum CLOUD_COVER_LAND percent value for Landsat images included in interpolation
collections STRING

List of Landsat collections for Landsat images included in the interpolation
core_version STRING

OpenET core library version
end_date STRING

End date of month
et_reference_band STRING

Band in et_reference_source that contains the daily reference ET data
et_reference_resample STRING

Spatial interpolation mode to resample daily reference ET data
et_reference_source STRING

Collection ID for the daily reference ET data
interp_days DOUBLE

Maximum number of days before and after each image date to include in interpolation
interp_method STRING

Method used to interpolate between Landsat model estimates
interp_source_count DOUBLE

Number of available images in the interpolation source image collection for the target month
mgrs_tile STRING

MGRS grid zone ID
model_name STRING

OpenET model name
model_version STRING

OpenET model version
scale_factor_count DOUBLE

Scaling factor that should be applied to the count band
scale_factor_et DOUBLE

Scaling factor that should be applied to the et band
start_date STRING

Start date of month

Terms of Use

Terms of Use

CC-BY-4.0

Citations

Citations:

  • Fisher, J.B., Tu, K.P. and Baldocchi, D.D., 2008. Global estimates of the land–atmosphere water flux based on monthly AVHRR and ISLSCP-II data, validated at 16 FLUXNET sites. Remote Sensing of Environment, 112(3), pp.901-919. doi:10.1016/j.rse.2007.06.025

  • Abdelrady, A., Timmermans, J., Vekerdy, Z. and Salama, M., 2016. Surface energy balance of fresh and saline waters: AquaSEBS. Remote sensing, 8(7), p.583. doi:10.3390/rs8070583

DOIs

Explore with Earth Engine

Code Editor (JavaScript)

var dataset = ee.ImageCollection('OpenET/PTJPL/CONUS/GRIDMET/MONTHLY/v2_0')
  .filterDate('2020-01-01', '2021-01-01');

// Compute the annual evapotranspiration (ET) as the sum of the monthly ET
// images for the year.
var et = dataset.select('et').sum();

var visualization = {
  min: 0,
  max: 1400,
  palette: [
    '9e6212', 'ac7d1d', 'ba9829', 'c8b434', 'd6cf40', 'bed44b', '9fcb51',
    '80c256', '61b95c', '42b062', '45b677', '49bc8d', '4dc2a2', '51c8b8',
    '55cece', '4db4ba', '459aa7', '3d8094', '356681', '2d4c6e',
  ]
};

Map.setCenter(-100, 38, 5);

Map.addLayer(et, visualization, 'OpenET PT-JPL Annual ET');
Open in Code Editor
Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) The core formulation of the PT-JPL model within the OpenET framework has not changed from the original formulation detailed in Fisher et al. (2008). However, enhancements and updates to model inputs and time integration for PT-JPL were made to take advantage of contemporary gridded weather …
OpenET/PTJPL/CONUS/GRIDMET/MONTHLY/v2_0, evapotranspiration,gridmet-derived,landsat-derived,monthly,openet,water,water-vapor
1999-10-01T00:00:00Z/2024-12-01T00:00:00Z
25 -126 50 -66
Google Earth Engine