Toneo Kawanishi

The Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E), NASDA's contribution to the EOS for global energy and water cycle studies

The Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) was developed and provided to the National Aeronautics and Space Administrations EOS Aqua satellite by the National Space Development Agency of Japan, as one of the indispensable instruments for Aquas mission. AMSR-E is a modified version of AMSR that was launched December 2002 aboard the Advanced Earth Observing Satellite-II (ADEOS-II). It is a six-frequency dual-polarized total-power passive microwave radiometer that observes water-related geophysical parameters supporting global change science and monitoring efforts. The hardware improvements over existing spaceborne microwave radiometers for Earth imaging include the largest main reflector of its kind and addition of 6.925-GHz channels. These improvements provide finer spatial resolution and the capability to retrieve sea surface temperature and soil moisture information on a global basis. This paper provides an overview of the instrument characteristics, mission objectives, and data products.

Development of precipitation radar onboard the Tropical Rainfall Measuring Mission (TRMM) satellite

The precipitation radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite is the first spaceborne radar to measure precipitation from space. The PR, operating at 13.8 GHz, is a 128-element active phased array that allows a fast and sophisticated cross-track scanning over a swath width of 215 km with a cross-range spatial resolution of about 4.3 km. The PR has a minimum detectable rain rate of 0.5 mm/h with range resolution of 250 m. In order to achieve a reliable and accurate rain echo data for three years mission life, functions for internal and external calibrations are implemented. Through a series of PR flight-model tests on the ground and an initial checkout just after the TRMM launch, it is confirmed that the PR functions properly and meets the performance requirements to quantitatively measure three-dimensional (3D) precipitation distribution from space.

TRMM Precipitation Radar

Abstract The Precipitation Radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite is the first spaceborne radar designed to measure the vertical structure of tropospheric precipitation. The PR, operating at 13.8 GHz, is a 128-element active phased array that allows fast and sophisticated cross-track scanning over a swath width of 215 km with a cross-range spatial resolution of about 4.3 km. The PR was designed to achieve a minimum detectable rain rate of 0.7 mm/h with a range resolution of 250 m. In order to achieve reliable and accurate rain echo data for a 3 year mission life, functions for internal and external calibrations have been implemented. After the launch of TRMM, a series of initial check-out was performed. In this presentation, we outline the PR system and the result of the initial check-out which confirms that the PR is functioning as expected.

TRMM precipitation radar

Precipitation Radar (PR) is a key sensor of the Tropical Rainfall Measuring Mission (TRMM) that is a U.S./Japan joint project to measure tropical and sub-tropical rainfall from space. The preliminary design of the PR has been completed and currently an engineering model is being developed. The PR consists of 128 T/R modules to construct an active phased array system at 13.8 GHz, and has the minimum measurable rain rate as low as 0.7 mm/h with a range resolution of 250 m, a horizontal resolution of about 4 km, and a swath width of 215 km. A combined internal and external calibration scheme is also being developed. In the presentation, system design, system parameters and calibration scheme as well as the development status of the PR are outlined.<<ETX>>

Four-year result of external calibration for Precipitation Radar (PR) of the Tropical Rainfall Measuring Mission (TRMM) satellite

External calibration experiments using active radar calibrator (ARC) were conducted for the calibration of the Precipitation Radar (PR) of the Tropical Rainfall Measuring Mission (TRMM) satellite from 1998 to 2001. Three modes of ARC operation are used for the experiment: the ARC transmitter mode for the receiver system of PR, the ARC receiver mode for the transmitter of PR, and the transponder mode for the overall system of PR. The experiments were conducted several times a year. The results of the experiments show that the performance of the PR is close to the prelaunch performance and that PR has been working stably for four years.

Instrument characteristics and calibration of AMSR and AMSR-E

The National Space Development Agency of Japan (NASDA) developed two spaceborne microwave radiometers: the Advanced Microwave Scanning Radiometer (AMSR) for NASDAs Advanced Earth Observing Satellite-II (ADEOS-II) and AMSR-E for NASAs Aqua satellite. Each instrument, as well as the combination of instruments, will provide valuable information for understanding the mechanism of global water and energy circulation. To accomplish the mission, it is necessary to provide reliable, well-calibrated data. Several post-launch calibration and validation activities are then planned in addition to two-point, on-board calibration of the instruments.

TRMM precipitation radar: calibration and data collection strategies

The strategy of TRMM Precipitation Radar (PR) calibration, including an external calibration scheme which employs active radar calibrators (ARCs) together with a special PR antenna scanning method, is discussed. This paper also covers data collection and processing schemes of the PR which were determined based upon scientific requirements and requirements of external calibration and onboard performance monitoring. Through the calibration, data collection and processing, the PR measurement is expected to provide a dataset which is valuable not only to obtain a reliable rainfall statistics but also detailed tropical storm properties.<<ETX>>

The functional evaluation model for the on-board hyperspectral radiometer

The hyper-multi spectral mission named HISUI (Hyper-spectral Imager SUIte) is the next Japanese earth observation project that will be on board ALOS-3 satellite. This project is the follow up mission of the Advanced Spaceborne Thermal Emission and reflection Radiometer (ASTER). HISUI is composed of hyperspectral radiometer with higher spectral resolution and multi-spectral radiometer with higher spatial resolution. The functional evaluation model is under development to confirm the spectral and radiometric performance prior to the flight model manufacture phase. This model contains the VNIR and SWIR spectrograph, the VNIR and SWIR detector assemblies with a mechanical cooler for SWIR, signal processing circuit and on-board calibration source.

Development results of TRMM precipitation radar

A precipitation radar (PR) has been developed by the National Space Development Agency of Japan (NASDA) in cooperation with the Communication Research Laboratory (CRL). The PR was integrated into the Tropical Rainfall Measuring Mission (TRMM) satellite and TRMM satellite system testing is ongoing by NASA. Throughout the various tests of PR it was confirmed that the PR satisfies its requirements.

On-orbit test and calibration results of TRMM precipitation Radar

Precipitation radar (PR) on-board the Tropical Rainfall measuring Mission (TRMM) satellite is the first rain radar to measure precipitation from space. After the successful launch of the TRMM satellite in last November, initial on- orbit test and calibration of the PR were conducted for about two months. From these tests, it was confirmed that on-orbit performances of the PR are fundamentally coincident with those verified at ground test and satisfy the specifications.