This data set contains measurements taken during the Soil Moisture Experiment 2005 (SMEX05) from 10 June 2005 through 03 July 2005 at Soil Climate Analysis Network (SCAN) station 2031 near Ames, Iowa USA. The data include hourly and daily recordings of precipitation, air temperature, solar radiation, wind speed, wind direction, relative humidity, barometric pressure, soil moisture, and soil ... temperature. The SCAN station houses numerous sensors which were used to automatically record the data, including a hydra probe, temperature and humidity probe, anemometer, precipitation sensor, pyranometer, and pressure sensor. Data were uploaded by meteor burst telemetry to the Natural Resources Conservation Service (NRCS) Data Processing Center in Portland, Oregon USA. The data are available in Comma Separated Values (CSV) files from the NRCS SCAN Web site. The Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) is a mission instrument launched aboard NASA's Aqua satellite on 04 May 2002. AMSR-E validation studies linked to SMEX are designed to evaluate the accuracy of AMSR-E soil moisture data. Specific validation objectives include: assessing and refining soil moisture algorithm performance; verifying soil moisture estimation accuracy; investigating the effects of vegetation, surface temperature, topography, and soil texture on soil moisture accuracy; and determining the regions that are useful for AMSR-E soil moisture measurements.