Masakatsu Nakajima

OPTIMIZATION OF THE ADVANCED EARTH OBSERVING SATELLITE II GLOBAL IMAGER CHANNELS BY USE OF RADIATIVE TRANSFER CALCULATIONS

The channel specifications of the Global Imager onboard the Advanced Earth Observing Satellite II have been determined by extensive numerical experiments. The results show that there is an optimum feasible position for each ocean color channel. The bandwidth of the 0.763-microm channel should be less than 10 nm for good sensitivity to the cloud top height and geometric thickness of the cloud layer; a 40-nm bandwidth is suitable for the 1.38-microm channel to have the strongest contrast between cloudy and clear radiance with a sufficient radiant energy; and a 3.7-microm channel is better than a 3.95-microm channel for estimation of the sea surface temperature (SST) and determination of the cloud particle size when the bandwidth of the channel is 0.33 microm. A three-wavelength combination of 6.7, 7.3, and 7.5 microm is an optimized choice for water vapor profiling. The combination of 8.6, 10.8, and 12.0 microm is suitable for cloud microphysics and SST retrievals with the split-window technique.

Reduction of the Barrier Height of Silicide/p-Si1-xGex Contact for Application in an Infrared Image Sensor

Silicide/p-Si1-xGex Schottky contacts were studied for using in an infrared (IR) image sensor. Si1-xGex layers were grown on p-type (100) Si substrates by using molecular beam epitaxy (MBE). Schottky barrier heights of PtSi(Ge) or PdSi(Ge)/p-Si1-xGex contacts decreased as the Ge content increased. When the Si1-xGex layer was strained, the barrier height was smaller than when relaxed for the same value of x. These results suggest the possibility of a long wavelength (8–12 µm) IR image sensor using a silicide/p-Si1-xGex Schottky contact for the strained layer monolithically grown on a p-Si CCD substrate.

Mission overview and instrument concept of the Global Imager (GLI)

In 1999, ADEOS-II is planned to launch. This satellite aims to observe the global changes of environment based on the carbon, water and energy cycle. For this purpose, ADEOS-II will carry several mission equipments. One of them is GLI (GLobal Imager). GLI is the imaging radiometer possible to observe various objects, for example, ocean color, sea surface temperature, vegetation index, cloud distribution, ice on the land and sea. To satisfy these abilities various methods will be applied to GLI. Collecting Optics consists of 2 off-axis parabolic mirrors to avoid the obstruction in the field of view. Interference filter are joined each other to set up many filter in the focal plane. Both faces of scan mirror will be used in terms of extending the integration time of detectors. In this report these methods and mission of GLI will be described.

Development of ADEOS-II/GLI operational algorithm for earth observation.

GLI (Global Imager) is a 36 channel visible and infrared radiometer/imager onboard the NASDA/ADEOS-II satellite. The information carried by GLI for the earth-atmosphere system is huge and difficult to be extracted enough efficiently with an operational satellite data analyzing system. We discuss and overview the algorithm development of the GLI Level-2 products at NASDA/EORC. We have several innovations to make the system unique and efficient. GLI simulator and GLI synthetic data sets are among those, which will be useful even for the science and engineering communities of other earth observation satellite systems. We will also overview the current status of the entire GLI project.

Current status of the ADEOS-II/GLI Mission

The design of the global imager (GLI) on board the ADEOS-II satellite is discussed to realize an efficient radiometer for monitoring the Earths surface and lower atmosphere. The GLI has 36 channels allocated over a wide spectral range between 0.38 micrometers and 12 micrometers for retrieving various geophysical parameters important for climate systems studies, such as cloud and aerosol microphysical parameters, ocean color pigments, vegetation indices, snow/ice microphysical parameters, and so on. Land surface and cloud detections are further enhanced by its six 250 m channels spectrally similar to LANDSAT/TM channels. The science issues relevant for the GLI mission are also briefly discussed.

One-year operation of TANSO-FTS on GOSAT and follow-on mission feasibility

The Greenhouse gases Observing SATellite (GOSAT) was developed to contribute to monitoring of carbon dioxide and methane from space [1]. The mission objectives are global greenhouse gas measurements from space with precision of 1 % for CO2 and 2 % for CH4 in seasonal mean. The GOSAT carries Thermal And Near infrared Sensor for carbon Observation (TANSO) for precise measurement of greenhouse gases. Main instrument is Fourier Transfer Spectrometer (TANSO-FTS) to observe atmospheric absorption spectra of CO2 and CH4 with high spectral resolution of 0.2 cm-1, broad wavelength coverage of 0.76 − 14.3 microns, wide swath of 790 km and frequent revisit of 3 days. Cloud and Aerosol Imager (TANSO-CAI) is simultaneously on board for cloud detection and correction of optical thin cirrus and aerosol interference within the FTS instantaneous field of view. The GOSAT satellite was launched by H2A-15 rocket on January 23, 2009. The Level 1B products of calibrated spectra were released from September 2009 in public. The Level 2 products of CO2 and CH4 column densities were released from February 2010 [2]. The normal observation data is acquired over one year regularly from April 2009. The mission lifetime is 5 years.

The development of CO2 dial for the calibration and validation of GOSAT data

JAXA developed the ground test model of DIAL, Differential absorption Lidar, to measure the quantities of the carbon dioxide for the calibration and the validation of the data acquired by the one instrument, TANSO-FTS, aboard on the GOSAT, Greenhouse gases observing satellite. FTS is the Fourier Transform Spectrometer. In addition to using for the calibration and the validation, this DIAL system has the purpose to take the data for the study of the space-borne DIAL. Our CO2 DIAL system adopted the 1.6 micron CW laser, incoherent detection and all fiber optical circuit. The transmitted on-line and off-line signals are coaxial and have the same field of view and the same time oscillation. And the transmitted laser is modulated doubly, intensity modulation by micro wave and phase modulation. This double modulation is adopted to detect the distance between the DIAL system and the target. JAXA is now performing the test of this DIAL to confirm the accuracy of the measurement of the carbon dioxide. This ground test model can be aboard on an airplane, therefore JAXA is planning the test using an airborne as a part of the test of the ground test model. In addition the comparison with the other CO2 DIAL systems is under consideration. Now JAXA does not have the plan to develop the space-borne LIDAR, however the space-borne LIDAR system has been under study recently, therefore JAXA intends to take the data which will be reflected in the design of the space-borne CO2 DIAL system through this test of the ground test model of DIAL.

Japan's strategy for earth observation by spaceborne infrared instruments

New type of infrared instruments such as Tunable Etalon Remote Sounder for the Earth (TERSE) and High resolution Limb Infrared Absorption Spectrometer (HLAS) were proposed and studied for the future Japanese earth observation satellite program. This paper describes the results of feasibility study of TERSE and HLAS.

Airborne Mie lidar with diode-pumped Nd:YAG, Nd:YLF laser for simulation of lidar system in space

Lidar in space have been featuring as a high sensitive active sensor for global observations of aerosol, cloud, water vapor, wind vector etc. Numerous efforts have been carried out toward realization of those by many researchers. NASDA also started a space lidar program from 1990. A present status of this program is a Phase A. The Phase A was highly directed to resolve system parameters of bookstore lidars, DIAL for measurements of global aerosol density, cloud height, vertical and horizontal distribution of water vapor concentration etc. and to develop an airborne lidar system, including high power diode-pumped Nd:YAG, Nd:YLF lasers, to obtain data for simulation of space lidar. This paper will describe the airborne lidar system with diode-pumped Nd:YAG, Nd:YLF lasers under development.