基于奇异谱分析的深圳近海净初级生产力时间序列研究

Study of the time series of net primary productivity in Shenzhen coastal waters based on singular spectrum analysis

海洋净初级生产力(Net Primary Productivity,NPP)长时间序列分析可获取NPP多年变化趋势、季节变化等动态信息,对海洋环境的监测与预报具有重要意义。本文以2003~2013年月际尺度净初级生产力卫星遥感产品为数据源,通过奇异谱分析提取标准化净初级生产力时间序列的长期趋势和周期振荡特征。研究表明,①浮标监测数据的叶绿素a浓度、海表温度与MODIS的叶绿素a浓度、海表温度产品变化趋势基本一致,NPP时间序列产品可用于分析深圳近岸海域净初级生产力的变化趋势。②空间分布上,深圳西部海域的NPP和叶绿素a浓度远高于大鹏湾和大亚湾,大鹏湾和大亚湾的NPP和叶绿素a浓度均值及变化趋势非常接近。三个海区NPP、叶绿素a浓度、海表温度和光合有效辐射在季风转换期变化剧烈。③长期趋势上,深圳西部海域呈现2a周期波动趋势,在均值附近以年为周期上下波动。大鹏湾和大亚湾2003~2006年NPP低于平均水平,2008年后NPP开始以年为周期围绕平均值上下波动,2012年后NPP整体与均值持平。④周期特征上,深圳西部海域、大鹏湾和大亚湾的NPP呈"W"或"M"型周年变化,存在夏季主高峰(6~7月)和冬季次高峰(12~1月)。

Taking the monthly satellite remote sensing standard products of net primary productivity (NPP) as data source, we extracted the long-term trend and periodicity through automatic singular spectrum analysis. We determined that the chlorophyll a concentration and sea surface temperature of buoy data were consistent with that of the MODIS images. Moreover, the time series images of the MODIS NPP could be used for the analysis of the NPP in Shenzhen coastal waters. Spatially, the NPP and chlorophyll a concentration in Shenzhen coastal waters were higher than that in Dapeng Bay and Daya Bay, and the mean value and variation trend of the NPP and chlorophyll a concentration were closer between Dapeng Bay and Daya Bay. The marine parameters of the three sea areas significantly changed during the monsoon transition. In the long-term trend, a two-year periodic fluctuation around the mean value was detected in the Shenzhen west sea area. Meanwhile, the NPP was lower than the mean value from 2003 to 2006 in Dapeng Bay and Daya Bay. Moreover, the NPP fluctuated by a one-year period around the mean value after 2008 and almost equaled the mean value after 2012. In terms of the periodic characteristic, a double periodic oscillation with a summer peak in June and July and a winter peak in December and January was identified in the Shenzhen west sea area, Dapeng Bay, and Daya Bay.