Indicators of Coastal Water Quality: Change in Chlorophyll-a Concentration 1998-2007

The Change in Chlorophyll-a Concentrations 1998-2007 component of the Indicators of Coastal Water Quality Collection represents a tabular time series of the chlorophyll-a concentrations for each grid cell, derived from the "Indicators of Coastal Water Quality:: Annual Chlorophyll-a Concentration 1998-2007" data set. Chlorophyll-a concentrations are derived from NASA's Sea-viewing Wide Field-of-view Sensor (SeaWiFS). The grid cells are organized by country, and the percentage of change from 1998-2007 is calculated for each cell. Each time series was assessed with a linear regression, and cells with statistically significant trends in chlorophyll-a concentrations are identified. The rows of the table are linked to a sequence grid from the "Indicators of Coastal Water Quality:: Ancillary Data" collection to facilitate the mapping of the trend values for selected countries and areas of interest. The data are processed and compiled by the Columbia University Center for International Earth Science Information Network (CIESIN).
To provide tabular data on the trends of chlorophyll-a concentration on a pixel by pixel basis for identifying areas with improving, declining, and stable coastal water quality that can provide guidance for decision making in the context of coastal management.

《近岸水质指标数据集》中的1998-2007年叶绿素-a（Chlorophyll-a）浓度变化组分，是面向各网格单元的表格化时间序列数据集，其数据源为《近岸水质指标::1998-2007年年度叶绿素-a浓度》数据集。叶绿素-a浓度数据源自美国国家航空航天局（National Aeronautics and Space Administration, NASA）的海洋宽视场传感器（Sea-viewing Wide Field-of-view Sensor, SeaWiFS）。
该数据集的网格单元按国家进行组织，并针对每个单元计算了1998至2007年间的浓度变化百分比。所有时间序列均通过线性回归进行评估，同时识别出叶绿素-a浓度呈现统计学显著趋势的网格单元。该表格的行与《近岸水质指标::辅助数据》数据集的序列网格建立了关联，以便为选定国家和关注区域的趋势值绘制地图提供便利。本数据集由哥伦比亚大学国际地球科学信息网络中心（Center for International Earth Science Information Network, CIESIN）完成处理与汇编。
本数据集旨在提供逐像素的叶绿素-a浓度趋势表格数据，以识别近海水质改善、恶化及保持稳定的区域，从而为近海管理相关的决策制定提供指导依据。