Notice to Data Users: The documentation for this data set was provided solely by the Principal Investigator(s) and was not further developed, thoroughly reviewed, or edited by NSIDC. Thus, support for this data set may be limited. This data set is comprised of in situ data collected as part of the Soil Moisture Experiment 2004 (SMEX04). Soil samples were collected from 30 July through 25 August ... 2004 in the regional study area of Arizona, USA. Parameters for this data set include sample bulk density, soil bulk density, gravimetric soil moisture, percent rock by weight, and percent rock by volume. Four data files are provided: two containing raw data and two containing field averages. Total volume for this data set is approximately 33 KB. Data are provided in ASCII text files and are available via FTP. These data were collected as part of a validation study for the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E). 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.