ADEOS Science Program Digest

There are eight sensors on board ADEOS, provided by five agencies from three countries. The scientific objective of ADEOS is to contribute to the understanding of the global environment, especially global warming and stratospheric ozone depletion. Each sensor provider has its own science program for its sensor. The ADEOS science program is composed of these science programs. However, NASDA's ADEOS science program is larger than other programs of sensor providers because of its role as the platform provider. This paper describes the current status of NASDA's ADEOS science program.

NASDA established the ADEOS science program in order to ensure that the ADEOS data processing and analysis proves valuable for Earth system science. The major ADEOS science program activities are listed below.

• Planning of ADEOS Science Program
• Algorithm Development
• Data Set Generation
• Calibration and Validation
• Field Campaigns
• Establishment of In-Situ Data Base
• Management of Research Activities under Research Anouncement Program
• Review of ADEOS Data Information System
• Coodination of Scientific Mission Operation Requirement
• Dissemination and PR Activities

Algorithm Development

Various algorithms have been developed in the ADEOS Science Program. The optimal algorithm is selected for NASDA based on the evaluation of these algorithms.

1. Standard Product Algorithm - Most products NASDA provides to users are standard products. EOC is provided with the optimal algorithm for product generation. This algorithm could be upgraded.

2. Quasi-standard Product Algorithm - EORC develops a quasi-standard product which is processed from standard product, a quasi-standard product algorithm is also developed.

3. ADEOS Lower-Level Dataset Algorithm - EORC develops lower-level datasets that satisfy user requirements and contribute to enhancing environmental research. Algorithms for generating these datasets are also developed.

4. ADEOS Higher-Level Dataset Algorithm - EORC generates higher-level datasets to further promote environmental research. Algorithms for generating these datasets are also developed.

Data Set Generation

One of the most important tasks of the ADEOS science program is to offer data sets derived from ADEOS data to Earth scientists for global change studies. The planned value added datasets are listed in the table below. "96" indicates datasets that can be produced relatively soon after launch (about 6 months after launch); "99" indicates that necessary algorithms will be developed before the termination of the ADEOS mission, and the datasets can be produced (within 3 years after launch). This table shows the current plan and may change as the ADEOS Science Program progresses.

Calibration and Validation

ADEOS carries eight sensors, including OCTS and AVNIR, with capabilities of higher precision measurements of ocean surface temperature, chlorophyll concentration and other atmospheric characteristics. Calibration and validation for OCTS and AVNIR are summarized below.

1. OCTS - Evaluation of image quality, sensor calibration and validation of measured data are carried out after launch in order to achieve more sensitive observation. The evaluation of image quality gives a priority to fundamental image characteristics such as spatial resolution and saturation rate as well as product quality. The evaluations continue for the first six months after launch.

2. AVNIR - Image quality evaluation, sensor calibration and validation of measured data are carried out by the same procedures as used with OCTS. However, sensors are calibrated using data acquired by satellite-borne and airborne sensors. In the measured data validation, surface reflectance and Digital Evaluation Model (DEM) are compared with ground truth data and the algorithm is evaluated.

3. Aircraft Experiments - Data acquired by airborne sensors is used as a sensor calibration source. The operation principle is to calibrate a sensor based on comparison of the satellite data and the radiance estimated from airborne data. The aircraft experiment is carried out by using NASA/JPL's onboard AVIRIS over four points along the west coast of U.S., including Edwards Air Base, in the land mode of AVIRIS/OCTS and over offshore California in the ocean mode of OCTS. The experiment is planned for two weeks every six months after launch.

4. Acquisition of Ocean Color Data
   Buoy - An ocean observation buoy which NASDA has developed will be placed in the Yamato-tai (Japan Sea) after ADEOS launch. It will serve as a fixed observation point giving measurement of irradiance and radiance reflectance, wind speed and direction, and ocean surface temperature. About 30 cloudless datasets will be obtained in a year.
   Ocean Data Acquisition Experiments in Cooperation with the Fishery Agency - The ADEOS sensors are designed to obtain data on radiance, chlorophyll concentration and ocean surface temperature, which are also measured by the ocean observation buoy. About 200 cloudless datasets will be obtained in a year.

5. Sea Surface Temperature (SST) - The data obtained by the buoy NOAA placed in the Pacific Ocean will be used to validate the SST data provided by OCTS. About 1,000 cloudless datasets will be obtained in a year.

6. Atmospheric Data - The atmospheric data correction routine, an element of the OCTS algorithm, is validated using atmospheric data obtained in Hokkaido, Niigata, Kanazawa and Okinawa.

7. DTL Receivers - Twelve DTL receivers will be manufactured from March 1996 and will be supplied in October 1996. The DTL receivers will then be installed at collaborative research agencies such as the Fisheries Agency (including Ocean Research Institute at the University of Tokyo and the National Institute of Polar Research), for further application of OCTS data in the fishery field and other practical uses.

Field Campaigns

In order to assure the quality (accuracy) of these data sets, we must sufficiently calibrate sensors and validate data products. Although sensor providers are responsible for calibrating and validating their own sensor, NASDA, as both the platform provider and as a sensor provider for AVNIR and OCTS, will establish its CAL/VAL plan for ADEOS. The main components of this ADEOS CAL/VAL are field campaigns dedicated to multiple sensors on board ADEOS. Hence, cross calibration and validation are the focus of these ADEOS field campaigns. The draft plans of these ADEOS field campaigns are listed below.

1. Calibration

   Primary objective	Calibration and cross calibration of ADEOS sensors
   Test site	California, USA
   Time period	Feb. 1997

2. Validation - Ocean

   Primary objective	Validation of oceanic geophysical parameters
   Test site	Off shore of Sanriku, Northwest Pacific
   Time period	May 1997

3. Validation - Atmosphere

   Primary objective	Validation of atmospheric geophysical parameters
   Secondary objective	Snow and ice studies
   Test site	Fairbanks and Barrow, Alaska, USA
   Time period	April 1997

4. Validation - Vegetation

   Primary objective	Validation of vegetation parameters
   Secondary objective (Test site 2)	Validation of ozone
   Test site 1	Paso, Malaysia
   Time period	July 1997
   Test site 2	Yakutsk, Siberia, Russia
   Time period	Sep. 1998

Establishment of In-Situ Data Base

Field campaigns described above can provide valuable data for calibrating and validating ADEOS data processing and analyses. However, these data are essentially local data in time and space. We need much more in-situ data, not only for calibration and validation but also for data processing and analyses. In order to collect and manage these in-situ data for ADEOS science, NASDA is going to establish the ADEOS in-situ data base.

This ADEOS in-situ data base will be composed of many kinds of in-situ data, including data from field campaigns, data collected by ADEOS PIs, and data from existing data base such as meteorological data.

This data base will be established at the Earth Observation Research Center (EORC) which was established in April 1995 in Tokyo. Those data collected in the ADEOS in-situ data base, except some classified data, will be distributed to ADEOS PIs.

Management of Research Activities under Research Anouncement Program

NASDA has already issued two research announcements jointly with other sensor providers. The first research announcement was issued jointly with the Ministry of International Trade and Industry and the Japan Environmental Agency, and focused on general aspects of ADEOS science. Around 150 PIs have already been selected through this joint research announcement (JRA). Another JRA was issued with CNES, France, and focused on POLDER science.

We are going to issue a third JRA in 1995 focused on using ADEOS data in Southeast Asia and a fourth JRA focused on specific areas which the first JRA PIs do not cover.

Coodination of Scientific Mission Operation Requirement

Mission operation coordination is also important for the ADEOS science program. Although most ADEOS sensors are global sensors and will be operated continuously, some sensors have operations requirements. One typical sensor with operational requirements is AVNIR. AVNIR will be operated only on demand. Another problem of AVNIR is related to its pointing capability. Therefore, mission operation conflicts among the several requirements may occur.