Reference and Potential Evapotranspiration

Science Center Objects

Evapotranspiration can be computed as reference, potential, or actual evapotranspiration.   Reference evapotranspiration is that from a grass surface that is well-watered.  Potential evapotranspiration is that from a surface that has unlimited water (such as a lake). 

Reference and potential evapotranspiration are computed at a 2-kilometer spatial resolution and daily timestep for the state of Florida, including both land and lakes surfaces.  Data and metadata are provided for each calendar year.  The methodology used to compute evapotranspiration from 1995-2015 is described by Mecikalski and others (2018; https://doi.org/10.1061/(ASCE)IR.1943-4774.0001312).  Methodology for other years are summarized in associated metadata files.

The statewide evapotranspiration data can be downloaded using the links provided below. Data are in NetCDF format (2019) or as tab-delimited tables (1985-2018). Tab-delimited data can be imported into a variety of GIS, database or spreadsheet software packages. See tables below for more information on file content.
 

Daily Reference (RET or ETo) and Potential (PET) Evapotranspiration data over Florida from 2018 (for previous years, see below)

NetCDF formatted data are described in associated metadata files available through the link provided. Tab-delimited data are also described in associated metadata files and include the following fields:

Column header and definitions 
YYYYMMDD,   Date as year (YYYY), month (MM), day (DD)
Lat,    Latitude of Pixel value (decimal degrees)
Lon,    Longitude of Pixel value (decimal degrees)
Pixel,    Pixel ID number
PET,    Potential ET(millimeters per day)
RET,    Reference ET(millimeters per day)
RAD    Solar Radiation - Daily Insolation (MegaJoules per square meter per day)
Albedo, Surface albedo (unitless)
Rhmax,    Maximum Relative Humidity for day (percent)
Rhmin,    Minimum Relative Humidity for day (percent)
Tmax,    Maximum Temperature for day (degrees Celsius)
Tmin,    Minimum Temperature for day (degrees Celsius)
Ws,    Wind Speed (meters per second)

Notes concerning the current data sets:
Missing values are represented by the number -9999.99.

 

Evapotranspiration Data by State, daily quality codes, and GOES ET metadata from 1985 to 2017

 

Each compressed County archive file contains one data file having tab delimited columns of data, which include the following fields:

Column - Column definition
date,    Date data representation
latitude,    Latitude of Pixel value
longitude,    Longitude of Pixel value
pixel,    Pixel ID number
PET,    Potential ET(mm/day)
RET,    Reference ET(mm/day)
solar,    Solar Radiation - Daily Insolation (MegaJoules/sq meter/day)
RHmax,    Maximum Relative Humidity for day (%)
RHmin,    Minimum Relative Humidity for day (%)
Tmax,    Maximum Temperature for day (C)
Tmin,    Minimum Temperature for day (C)
Wind,    Wind Speed (meters/second)

Notes concerning the current data sets:
Missing values are represented by the number -9999.900.

Each compressed Daily Quality Code file contains one data file having tab delimited columns of data, which include the following fields:

Column - Column definition
date, Date
code, Data quality code (A value of 1, 2, 3, or 4 based on the quality of Solar data for that day)

( 1 = Good quality, 2 = Usable data, 3 = Uncertain or unverifiable quality, 4 = Unusable or missing)

 

 

Information regarding the methodology used in the ET computations are detailed in the InTechWeb Report: 
Use of Visible Geostationary Operational Meteorological Satellite Imagery in Mapping Reference and Potential Evapotranspiration over Florida