1997—2007年东海叶绿素a质量浓度的时空变化分析

分析了1997—2007年由SeaWiFS卫星获得的我国东海ρ(叶绿素a)的时空变化特点.结果表明，ρ(叶绿素a)多年平均值在近海明显高于外海，近海往外快速递减，最高值位于长江口大沙滩. 东海ρ(叶绿素a)呈明显的年周期性变化，波峰基本出现在3—4月，波谷在7—8月.在近11年间，ρ(叶绿素a)及距平呈下降趋势，最显著的是在东海近海海区. ρ(叶绿素a)及距平的变化具有明显的区域性，东海北部近海多年的月均值最高〔ρ(叶绿素a)>2.0 mg/m3〕，南部近海和台湾海峡次之(0.8～2.0 mg/m3)，东海北部和南部外海最小〔ρ(叶绿素a)<1.0 mg/m3〕. 近海主要受到陆地径流带来富营养盐的影响，ρ(叶绿素a)高、变化幅度大、周期短，东海外海及台湾海峡主要受到高温寡营养盐的黑潮及其分支影响，ρ(叶绿素a)低、变化幅度小、周期长. 

Temporal-spatial Change of Concentration of Chlorophyll-a in the East China Sea During 1997-2007

The temporal-spatial changes of chlorophyll-a concentration 〔ρ(chl-a)〕 obtained by SeaWiFS in the East China Sea (ECS) during 1997-2007 were analyzed. The results showed that the annual average ρ(chl-a) in the inshore areawas much higher than that in the offshore; the average sharply decreased from inshore to offshore; and the highest ρ(chl-a) was located in the estuary of the Yangtze River. In the ECS, ρ(chl-a) showed a significant annual cycle,reachingthe highest in March and April and the lowest in July and August every year. Inthe recent 11 years, ρ(chl-a) and annual anomalies decreased in the ECS, especially in the inshore. ρ(chl-a) was the highest (>2.0 mg/m3) in the north inshore, and was higher (0.8-2.0 mg/m3) in the south inshore and the Taiwan Strait, and was the lowest (<1.0 mg/m3) in the north and south offshores. The ρ(chl-a) in the inshore of the ECS was mainly affected by the rich nourishment brought bythe land flows, which resulted in high ρ(chl-a), great change and short period. ρ(chl-a) in the offshore and Taiwan Strait was largely impacted by the Kuroshio and its offset, which resulted in low ρ(chl-a), little change and long period.