黒潮水域を中心とした高精度海況日報の作成手法

抄録

In order to furnish daily high-resolution sea surface temperature (SST) to fishermen, who are always looking for data to help in locating good fishing grounds, a method for obtaining daily SST for each 1/40° grid was presented and discussed. For this purpose, AVHRR SST is very valuable because of the high ground resolution of 1.1km. AVHRR SST, however, cannot be obtained under cloud and this often leads to sporadic SST distribution. To overcome this, we prepared a daily composite SST from SSTs collected in the past 5 days. If an SST was lacking, the SST was interpolated from available SSTs at surrounding grids. The composite SSTs were often different from directly observed SSTs. Accordingly, in order to improve data quality, the daily composite SSTs were compared with SSTs observed directly from boats and buoys along with remotely sensed AQUA/AMSR-E SSTs. Average temperature difference and standard deviation between composite SSTs and the latter two SSTs were calculated. To select high-quality SSTs, composite SSTs with a temperature difference two times larger than the standard deviation were eliminated. At the same time, all selected composite SSTs were corrected by the average temperature difference. These selecting and correcting procedures were reiterated until the standard deviation of the temperature difference became smaller than 0.5°C. Selecting highquality composite SSTs, however, resulted in a lack of data at some grids. Accordingly, they were interpolated or extrapolated from those at the nearest grids. The composite SSTs were finally corrected using the temperature difference obtained.