Basics of Evaporation and Evapotranspiration - (PDF) University of Arizona Cooperative Extension, AZ1194
Crop Evapotranspiration: Guidelines for Computing Crop Water Requirements - The Food and Agriculture Organization (FAO) of the United Nations presents a procedure for calculating reference and crop evapotranspiration from meteorological data and crop coefficients. These guidelines are intended for project managers, consultants, irrigation engineers, hydrologists, agronomists, meteorologists, and students. They can be used for computing crop water requirements for both irrigated and rainfed agriculture, and for computing water consumption by agricultural and natural vegetation.
Evaporation Pan Coefficients - Table of pan coefficients for Class A and Sunken Colorado pans for different ground cover and levels of mean relative humidity and 24 hour wind. From the Food and Agriculture Organization (FAO) of the United Nations.
Instructions for the Installation and Operation of Class "A" Evaporation Stations - by Benjamin Clinton Kadel, United States Department of Agriculture, Weather Bureau, Instrument Division, W.B. No 559, Circlular L, issued October 16, 1915. (Digitized by Google Books.)
NOAA Technical Report NWS 33 - Evaporation Atlas for the Contiguous 48 United States - (PDF) Maps are presented showing the areal distribution in the contiguous 48 states of evaporation (1) observed from Class A pans from May through October, (2) estimated for a free water surface (FWS) with negligible heat storage from May through October, and (3) estimated for an FWS for the entire year. A map is presented of coefficients to convert from pan evaporation to FWS evaporation.
NOAA Technical Report NWS 34 - Mean Monthly, Seasonal, and Annual Pan Evaporation for the United States - (PDF) This publication is a compilation of monthly, seasonal, and annual averages of estimated pan evaporation based on observations from Class A pans and on meteorological measurements by the National Weather Service (NWS) and cooperating agencies. It replaces Technical Paper No. 13 (U.S. Weather Bureau, Hydrologic Branch, Division of Climatological and Hydrologic Services, 1950). These tabulations were generated from the augmentation of a smaller data set used to develop evaporation maps published in NOAA Technical Report NWS-33.
NWS Observing Handbook No. 2: Cooperative Station Observations - Section 5 provides instructions on installing and maintaining a manual evaporation station. (PDF 1.4MB 94 pages)
Siting and Maintance of Weather Stations for Computing Evapotranspiration - University of Arizona Cooperative Extension (PDF 90KB 5 pages)
Use and construction of a lysimeter to measure evapotranspiration - by Donald Perkins
Using Modified Atmometers (ETgage) for Irrigation Management - This guide from the University of Nebraska describes the atmometer (evapotranspiration gage) and explains how it can be used for irrigation scheduling. Examples are provided to show how information collected with an atmometer can be used to estimate crop water use for corn and soybean.