OpenET CONUS SSEBop Monthly Evapotranspiration v2.0

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conus evapotranspiration gridmet-derived landsat-derived monthly openet water


Operational Simplified Surface Energy Balance (SSEBop)

The Operational Simplified Surface Energy Balance (SSEBop) model by Senay et al. (2013, 2017) is a thermal-based simplified surface energy model for estimating actual ET based on the principles of satellite psychrometry (Senay 2018). The OpenET SSEBop implementation uses land surface temperature (Ts) from Landsat (Collection 2 Level-2 Science Products) with key model parameters (cold/wet-bulb reference, Tc, and surface psychrometric constant, 1/dT) derived from a combination of observed surface temperature, normalized difference vegetation index (NDVI), climatological average (1980-2017) daily maximum air temperature (Ta, 1-km) from Daymet, and net radiation data from ERA-5. This model implementation uses the Google Earth Engine processing framework for connecting key SSEBop ET functions and algorithms together when generating both intermediate and aggregated ET results. A detailed study and evaluation of the SSEBop model across CONUS (Senay et al., 2022) informs both cloud implementation and assessment for water balance applications at broad scales. Notable model (v0.2.6) enhancements and performance against previous versions include additional compatibility with Landsat 9 (launched Sep 2021), global model extensibility, and improved parameterization of SSEBop using FANO (Forcing and Normalizing Operation) to better estimate ET in all landscapes and all seasons regardless of vegetation cover density, thereby improving model accuracy by avoiding extrapolation of Tc to non-calibration regions.

Additional information


30 meters


Name Units Description
et mm

SSEBop ET value

count count

Number of cloud free values

Terms of Use

Terms of Use



  • Senay, G.B., Parrish, G.E., Schauer, M., Friedrichs, M., Khand, K., Boiko, O., Kagone, S., Dittmeier, R., Arab, S. and Ji, L., 2023. Improving the Operational Simplified Surface Energy Balance Evapotranspiration Model Using the Forcing and Normalizing Operation. Remote Sensing, 15(1), p.260. doi:10.3390/rs15010260

  • Senay, G.B., Bohms, S., Singh, R.K., Gowda, P.H., Velpuri, N.M., Alemu, H. and Verdin, J.P., 2013. Operational evapotranspiration mapping using remote sensing and weather datasets: A new parameterization for the SSEB approach. JAWRA Journal of the American Water Resources Association, 49(3), pp.577-591. doi:10.1111/jawr.12057

  • Senay, G.B., Schauer, M., Friedrichs, M., Velpuri, N.M. and Singh, R.K., 2017. Satellite-based water use dynamics using historical Landsat data (1984–2014) in the southwestern United States. Remote Sensing of Environment, 202, pp.98-112. doi:10.1016/j.rse.2017.05.005c

  • Senay, G.B., 2018. Satellite psychrometric formulation of the Operational Simplified Surface Energy Balance (SSEBop) model for quantifying and mapping evapotranspiration. Applied Engineering in Agriculture, 34(3), pp.555-566. doi:10.13031/aea.12614

  • Senay, G.B., Friedrichs, M., Morton, C., Parrish, G.E., Schauer, M., Khand, K., Kagone, S., Boiko, O. and Huntington, J., 2022. Mapping actual evapotranspiration using Landsat for the conterminous United States: Google Earth Engine implementation and assessment of the SSEBop model. Remote Sensing of Environment, 275, p.113011. doi:10.1016/j.rse.2022.113011


Explore with Earth Engine

Code Editor (JavaScript)

var dataset = ee.ImageCollection('OpenET/SSEBOP/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 ='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 SSEBop Annual ET');
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