2. OBSERVATION AND MONITORING

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2.1 GAME Satellite Remote Sensing Program

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2.1.1 Scientific goals

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The variability of large-scale energy and hydrological processes of Asian monsoon system has been suggested to affect the global climate. They should be monitored from diurnal to interannual time scale at least for ten years. However, there are fewer ground observational stations in monsoon Asia. Due to dynamic behavior of the parameters for the energy and hydrological processes (i.e., cloud, water vapor, precipitation, wind, snow cover, albedo, soil moisture, surface temperature etc.), efficient monitoring is possible only by using satellite remote sensing.

In turn, the field observations and process studies related to GAME would function as a ground-truth and algorithm study for the satellite observations. The objective of the GAME satellite remote sensing project is to develop observing techniques of energy and water cycle over the Eurasian continent.

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2.1.2 Program strategy

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(1) Data set generation

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a) The operational satellites, such as GMS, NOAA and DMSP series have already been providing us homogeneous and continuous information on the fundamental properties of the hydrosphere and atmosphere. The data set generation activities of GEWEX such as ISLSCP, GPCP and ISCCP have already released the uniform, consistent global data sets. GAME plans to generate two kinds of data sets over the Eurasian continent as follows:

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? 1st order data sets: vegetation indices, surface albedo, surface temperature,

surface wetness, surface roughness, snow covered area,

snow water equivalent, precipitation,

net radiation budget at the top-of-atmosphere

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? 2nd order data sets: surface radiation budget, vertical sensible and latent heat fluxes

at the surface, horizontal heat and moisture fluxes

in the atmosphere

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The first order data sets are produced by the operational satellites with more specific but high-order information derived from the halfly-operational and halfly-experimental satellites, LANDSAT, EERS-2, JERS-1 and RADARSAT. The second order data sets are generated by combining atmospheric and hydrologic models with the first order data sets.

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b) ADEOS is the first satellite of this series and was successfully launched by NASDA on August, 1996. The ADEOS science program will produce the following data sets which would be related to GAME:

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? global vegetation index data set

? global Land-covering grouping data set

? global aerosol mapping data set

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c) TRMM, which is non sun-synchronous satellite and very unique mission dedicated to measure the tropical and sub-tropical rainfall, may be one of the most important satellites for GAME and GEWEX. A package of a rain radar and microwave and visible/infrared radiometer will be aboard on TRMM. Many kinds of data products will be generated by the TRMM project. Among them, the following products would considerably contribute to GAME.

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? Rainfall Structure data sets from PR, TMI and Combined

? 30 day Surface Rainfall data sets from PR and TMI

? 30 day Rainfall Structure data sets from PR and Combined

? Monthly Regional Radiative Fluxes and Cloud data set from CERES

? Monthly TOA and SRB Averages data set from CERES

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2) Algorithm development and data set verification in the regional experiments

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Four regional experiments, GAME-T, HUBEX, GAME-Tibet and GAME-Siberia, focus on the development of algorithms and data set verification for the following parameters:

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a) Precipitation

GAME-T, HUBEX and GAME-Tibet plans the deployment of 3-D Doppler radar, operational radar, rainguage networks and/or disdrometers for TRMM data verification. The radar observes various cloud types to precipitate, which are used to construct the algorithms to estimate precipitation area and rate from the Tbb distribution of geostationary satellites.

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b) Vertical distribution of water vapor

HUBEX focuses of the estimation of vertical distribution of water vapor by SSM/T-2 and AMSU-B data and its verification by data of intensified radio-sonde observation.

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c) Radiation budget

Radiative heating of atmosphere is an important issue over the Tibetan Plateau. To address this issue, the accuracy of estimation of the radiation budget at the land surface should be improved. GAME-Tibet plans ad hoc lidar observation of cloud base over Tibetan Plateau for development of an improved algorithms for surface radiation budget. Surface radiation and cloud data is planned to be obtained for verification of GMS/SVISSR data in GAME-T.

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d) Surface soil wetness

GAME-Tropics and GAME-Tibet plan to obtain the distribution of surface soil wetness for development and evaluation of the algorithms for SARs on JERS-1, EERS-2 and RADARSAT and passive microwave sensors on DMSP, TRMM investigated as the basis of monitoring the temporal and spatial distribution of hydrological states of frozen soil by using passive and active microwave sensors in GAME-Tibet and GAME-Siberia.

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e) Snow water equivalent

Climatological characteristics of snow parameters on the Tibetan Plateau obtained by field measurements, which are planned in GAME-Tibet and GAME-Siberia, are very useful for development of algorithms for passive microwave sensors on DMSP, TRMM and ADEOS2 and SARs on JERS-1, EERS-2 and RADARSAT. In turn, those algorithms should be validated by the field measurement data.

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3) Assimilation of satellites data

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Further advancement of the 4DDA system will be achieved by including newly developed satellite observation data with appropriate truth data, which may compensate for the sparsity of conventional observational data. In coming several years, new earth observing satellites, such as TRMM, ADEOS and advanced TOVS system will be available as well as the currently operated GMS, NOAA, ERS1 and DMSP equipped with SSM/I. In order to use these data effectively, we are going to develop data assimilation techniques of satellite data, such as physical initialization and three or four dimensional variation methods.