A precipitation retrieval algorithm is proposed for the dual-frequency precipitation radar (DPR) on the core satellite of the Global Precipitation Measurement mission. The proposed algorithm is called the HB-DFR algorithm, in reference to the combination of Histchfeld-Bordan's attenuation correction method (HB method) and the dual-frequency ratio (DFR) method. The HB-DFR algorithm is tested with a synthetic DPR dataset produced from the standard product of the PR on the Tropical Rainfall Measuring Mission. Precipitation rates estimated by the HB-DFR algorithm at the lowest (near-surface) range bin are evaluated by comparing them with the corresponding values calculated from the drop size distribution of the synthetic dataset. For “light precipitation” (below 1 mm h-1), precipitation rates are slightly underestimated because of the multiple-solution problem in the DFR method. For “heavy precipitation” (above 10 mm h-1), the precipitation rates are severely underestimated, and the biases become large when thick liquid phase precipitation occurs. For “medium precipitation” (between 1 and 10 mm h-1), the estimates are satisfactory. As almost 50 % of precipitation falls as medium precipitation in the synthetic dataset, this result validates the usefulness of DPR measurements and the HB-DFR algorithm. Because the HB-DFR algorithm is a forward retrieval algorithm, it has multiple solutions and produces larger errors when applied to lower (farther) range bins. Unlike other dual-frequency algorithms, the HB-DFR algorithm can be easily switched to a single-frequency algorithm at a range bin where a measurement at one of the two frequencies is not available.

Recent researches suggest that reduced cloud droplet effective radius by aerosol causes clouds to invigorate. The number of researches by observation data is still small and limited to tropical regions. To investigate this hypothesis, relationship between cloud droplet effective radius and cloud top height is examined globally by using CloudSat data product. The results show significant negative correlation between cloud droplet radius and cloud top height. This relationship is found to exist in the 2 m temperature range as low as 0-10 degree Celsius, which indicates that invigoration exists outside of tropical regions. The validity of the hypothesis that extra latent energy released by delayed phase change is also investigated from the aspect of temperature dependence. However, the results showed no dependence on 2 m temperature.

The measurement of spatially distributed water surface elevation (WSE) at the global scale, which is planned by "Surface Water and Ocean Topography (SWOT) mission", will bring lots of fresh knowledge on global-scale terrestrial water circulation especially when observed WSE is merged into global hydrodynamics modes by data assimilation. In this paper, we discussed the predictability of WSE by a global hydrodynamics model, which is required as a dynamic core for global-scale data assimilation using SWOT. From the comparison against WSE observed by the altimeter on Envisat, we found that the up-to-date global hydrodynamics model is able to reproduce the seasonal variations of WSE in the Amazon River, though predicted WSE still has errors due to the uncertainties in topographic parameters and sub-grid-scale dynamics of the model. Reduction of these uncertainties is required along with the development of the algorithm itself for achieving global scale data assimilation of WSE.

The Advanced Microwave Scanning Radiometer-2 (AMSR2) will be launched as a single mission instrument onboard on the first satellite of the Water Series of Global Change Observation Mission (GCOM-W1). AMSR2 is multi-frequency, total-power microwave radiometer system with dual polarization channels for all frequency bands, and a successor of AMSR on the Advanced Earth Observing Satellite-II (ADEOS-II) and AMSR for the Earth Observing System (AMSR-E) on NASA's Aqua satellite. Participation of GCOM-W1 on the A-Train constellation is now being coordinated. Current target launch year of GCOM-W1 is in Japanese fiscal year 2011. Although GCOM-W1 will not be capable of observing ocean surface vector winds, the future possibility of installing a U.S. provided scatterometer on GCOM-W2 is under discussion. Simultaneous active and passive microwave measurements will enhance the water cycle observation capability of the GCOM-W series.

The Japan Aerospace Exploration Agency (JAXA) is pursuing the Global Change Observation Mission (GCOM) that will inherit the Advanced Earth Observing Satellite-II (ADEOS-II) mission and develop into long-term monitoring. GCOM is not the name of a single satellite, but of a mission that consists of two series of medium-size satellites, GCOM-W (Water) and GCOM-C (Climate), and three generations of each satellite series to continue the observations for 10 to 15 years. The Advanced Microwave Scanning Radiometer-2 (AMSR2) will be the single instrument on the GCOM-W1 satellite, which is the first satellite of the GCOM series. The second satellite will be GCOM-C1, which will carry the Second-generation Global Imager (SGLI). GCOM-W will mainly contribute to the observations related to global water and energy circulation, while GCOM-C will contribute to the measurements related to the carbon cycle and radiation budget. Current target launch years are calendar year 2011 for GCOM-W1 and 2014 for C1.

For the purpose to detect the change of agricultural area in large irrigation districts in the Yellow River basin, the method to estimate the agricultural area accurately using coarse resolution sensor i.e. AVHRR was developed on the Ningxia irrigation district. The agricultural area was calculated with higher spatial resolution sensor i.e. Landsat ETM+ by land cover classification, and it was correlated with annual maximum NDVT derived from AVHRR in order to get the fraction of agricultural area within one AVHRR pixel. The AVHRR estimation result showed the good agreement with ETM+ calculation in the county based comparison.

A surface soil moisture estimation algorithm by microwave radiometer is developed with radiative transfer model for soil-vegetation-atmosphere layers (especially, vegetation layer is focused).