Abstract
The composite image are produced from HPRT data received at Tokyo University, Kuroshima (Japan), Ulaanbaatar (Mongolia) and Bangkok (Thailand). The compositing method is based on the selection maximum NDVI and minimum scan angle for land surface, and minimum value of channel 2 and maximum value of channel 4 for sea surface. The processing chain includes radiometric calibration, geometric registration, compositing and atmospheric correction. The final product is an image data set of 10 layers which include NDVI and SST, reflectances of channel 1 and 2, brightness temperature of channels 3, 4 and 5, sun-target-sensor geometry of sensor zenith, solar zenith and relative azimuth angles and measurement date of the each pixel selected. A prototype composite image was produced for the period of 1-10 August 1998 production of 10-day composite for 1998 is undertaking.

1.Introduction
The availability of daily Advanced Very High Resolution Radiometer (AVHRR) imagery which covers very large regions has been shown to be useful for monitoring global environmental conditions. However, the use of daily AVHRR data has difficulties because of obtaining sufficient cloud free images. AVHRR image, however, ahs major advantages such as high frequent overpass and wide scanning provides the chance of producing cloud free images by compositing AVHRR images collected in regular intervals. Taking these advantages of AVHRR, the compositing procedure which is a widely accepted technique for AVHRR data make it possible to produce cloud free composite data. The composite AVHRR data is particularly important for continues monitoring at regional and continental scales. However, for users of the data, it has been often showed difficult to collect, preprocess and produce multi-temporal AVHRR data set. A number of processed AVHRR data sets are conducted on imagery from North America, Sahelian Africa, South American and African tropical forest, European continent and also global land 1-km AVHRR data set (EROS DATA Center) is available for 1992-1995. In spite of the existing AVHRR data set for global and continental scale, there has been relatively little practical contribution to multi-temporal AVHRR database for Asian region is important attribute to fundamental understanding the ecology in Asian region.

In this paper we describes automatic processing system for generating 10-day composite image of AVHRR data for Asian region developed in the Laboratory of Remote Sensing Data Analysis, Iwate University.

2.The Composite Data Set
The AVHRR composite data set includes the region with the top left coordinate of 80oN, 50oW, and the bottom right of 20oS. 180oE, Data volume of the composite image of 14400 pixels and 1200 lines is 3.4GB. The composite image has 10 channels that include:

1. AVHRR channel 1 Reflectance (%)
2. AVHRR channel 2 Reflectance (%)
3. AVHRR channel 3 Brightness temperature (Centigrade)
4. AVHRR channel 4 Brightness temperature (Centigrade)
5. AVHRR channel 5 Brightness temperature (Centigrade)
6. Sensor zenith angle (degrees)
7. Solar zenith angle (degrees)
8. Relative azimuth angle (degrees)
9. NDVI-SST (sea surface temperature), NDVI for land SST for sea surface (Centigrade)
10. Julian day

During the discussions with scientific communities and various researchers, they suggested to use Plate Carree projection because of the simple use for the users. Therefore, Plate Carrree projection was selected.