“百合”台风对海表温度及水色环境影响的遥感分析

Analysis of the effects on surface temperature and ocean color environment by typhoon Nari based on remote sensing

利用SeaWiFS及NOAA卫星资料，基于均值合成算法，分析了“百合”台风对海表温度（SST）、海表叶绿素a浓度及海水透明度的影响，结果表明，整个研究海域（22°～30°N、121°～131°E）的平均SST从台风前的25．48℃下降到22．45℃，平均下降幅度为12．95％。在台风盘旋的中心区域（26°～28°N、123°～127°E），SST平均下降了5．40℃，下降幅度达21．20％，SST下降最大的是9月14日，整个研究海域平均SST仅为13．48℃。整个研究海域海表叶绿素“浓度在台风期间有较大的增加，从台风前的0．425mg／m^3（平均值）上升到0．537mg／m^3，平均增长26．35％。除浙江近海外，台风核心区域海表叶绿素a浓度增幅最大，达1．695倍，表明台风风力越强，台风停留时间越长，对海表叶绿素a浓度增加的贡献就越大。这一增加有利于海洋生物的生长，有利于提高初级生产力和改善海洋生态环境。在“百合”台风期间，海水透明度却有一定程度的降低，从台风前的16．84m（平均值）下降至台风后的12．67m，平均降幅为24．76％，降幅最大的是24°～26°N、125°～127°E区块，平均下降了7．96m，降幅高达47．6％；总体上台风核心区域南部的海水透明度降幅大于区域北部，台风核心区域东南部的海表叶绿素a浓度增幅大于区域东北部。同时，对整个研究海域分割成2°×2°大小的区块，以每个区块的海表叶绿素“浓度、SST和海水透明度的均值代表该区块的值，对台风前、后海表叶绿素a浓度、SST和海水透明度的变化进行相关性分析，发现海表叶绿素“浓度的变化与SST和海水透明度均呈负相关性，且台风期间海表叶绿素a浓度增加的百分比与相应区块海水透明度下降的百分比之间的相关系数达0．821。

As a result of global warming, bad weather happens frequently. Typhoon not only grows frequently, but also has a tendency to be more intense. The impact of typhoon on the marine environment gradually becomes a hotspot of global concerning. Owing to the bad weather during typhoon period, it is difficult to get the in situ measures. So satellite remote sensing is the main approach to study the impact of typhoon on the sea surface temperature （SST） and the ocean color environment at present. Typhoon Nari passing through the Northwest Pacific ocean from 6 to 18 September 2001 not only had a very special path, but also lasted for a particularly long time, and its life time hovering over the Ease China Sea was the longest in the past 10 years. In this article, the authors use the data of the SeaWiFS and NOAA satellites to analyses the effects of Nari on the sea surface temperature（SST）, sea surface chlorophyll-a concentration（CHL-a） and the ocean water transparency（SDD）, and found that： （1） in the entire study area （22-30°N, 121-131°E）, the average SST decreased from 25.48℃ to 22.45℃, with a mean dropping range of 12. 95%, and in the central area （26-28°N, 123-127°E） where the typhoon hovered from 7 to 14 of September, 2001, the average SST dropped 5.4℃, with a dropping range of up to 21.20%. The minimum SST occurred on the 14th of September, it was only 13.48℃ in the area. （2） the CHL-a averagely rose from 0. 425 mg/m3 before the typhoon to 0. 537 mg/m3 after Nari with an average increase of 26.35% in the whole studied sea area except for Zhejiang coastal waters, the core region had the greatest growth as much as 1. 695 times, which shows that the stronger the typhoon winds and the longer the typhoon stays, the greater is the contribution to the ris＇e of chlorophyll-a concentration. This rise is advantageous to the growth of the marine life and to the enhancement of primary productivity and the improvement of marine eco-environment. But the water transparency （SDD） dropped averagely from 16.84 m before the typhoon to 12.67 m during typhoon with a mean decrease of 24.76% in the whole studied sea area. In the area of 24-26°N, 125-127°E, it dropped averagely by 7.96 m, with a dropping range of up to 47.6%. As a whole, the range of SDD decrease to the south of the typhoon core area is greater than that to the north. And the rise of CHL-a to the southeast is higher than that to the northeast. The author divided the studied area into 20 blocks of 2°×2°, the meanvalue of chlorophyll-a concentration, sea surface temperature and sea water transparency are used as the value of the block, and their changes before and after the typhoon were analyzed, which shows that the change of the chlorophyll-a concentration is negatively correlated to the change of surface temperature and water transparency. The correlation coefficient between the growth percentage of Chl-a and the dropping percentage of SDD of the corresponding block during typhoon is 0. 821.