Version upgrade and new release of AMSR-E geophysical products
JAXA has started releasing version-upgrades and several new geophysical products of AMSR-E operating on the Aqua satellite from March 12, 2004. New geophysical products include soil moisture, snow depth, and integrated cloud liquid water.
This is the first time for us to release AMSR and AMSR-E soil moisture (*1) products. The amount of soil moisture affects evaporation from land surfaces and controls heat and water fluxes into the atmosphere. Although observing the soil moisture plays an important role in improving the process model for global climate change prediction and in providing useful information to regional agricultural production management, wide-area and quantitative measurement have been difficult. Figure 1 (*2) illustrates the seasonal change of the AMSR-E soil moisture around the Mongolian plateau from May to October 2003. Colors changing from blue to red indicate increasing soil moisture content.
Fig. 1 Soil moisture distribution around Mongolian plateau
(from May to October 2003)
Since in-situ measurements of soil moisture for validating satellite observations are still scarce, field measurements (*3) of weather and hydrological parameters including soil moisture are now being performed through cooperation between the World Climate Research Program (WCRP), JAXA, and the Institute of Meteorology and Hydrology (IMH) of Mongolia, as a part of the Coordinated Enhanced Observing Period (CEOP). This field measurement consists of continuous monitoring at several stations and multipoint moving observations to obtain area information during the predetermined Intensive Observing Periods (IOP). Since the surface condition of the Mongolian plateau is relatively uniform for wide areas, better comparison of the coarse resolution data by AMSR-E with the in-situ measurements is possible. This was the major reason for selecting the Mongolian plateau. The AMSR-E soil moisture estimates are validated by using the in-situ data obtained by this field measurement.
Fig. 2 Locations of AWS and ASSH during observation from 2002 to 2003.
Fig. 3 Upper photo shows deployed AWS system at Mandalgobi site. Lower photo indicates condition of buried ASSH instrument. Both photos were provided by Professor Kaihotsu of Hiroshima University.
Figure 2 depicts the deployed locations of the Auto Weather Station (AWS) and the Automatic Station for Soil Hydrology (ASSH) in Mongolia. Deployed conditions of AWS and ASSH are illustrated in Fig. 3. During the IOPs, strenuous efforts were made to obtain the wide-area in-situ measurements by driving along the trackless paths using 4x4 cars.
(*1) Weight of liquid water in unit volume of soil
(*2) Visualized by using AMSR-E soil moisture product (retrieval algorithm was developed by Professor Toshio Koike at the University of Tokyo). Each image is generated by averaging five days data at the beginning of a month.
(*3)Principal investigator is Professor Ichirow Kaihotsu at the Hiroshima University.
