Title

A new method to generate a high-resolution global distribution map of lake chlorophyll

Document Type

Conference Paper/Presentation

Publication Date

2015

Abstract

A new method was developed, evaluated, and applied to generate a global dataset of growing-season chlorophyll-a (chl) concentrations in 2011 for freshwater lakes. Chl observations from freshwater lakes are valuable for estimating lake productivity as well as assessing the role that these lakes play in carbon budgets. The standard 4-km NASA OceanColor L3 chlorophyll concentration products generated from MODIS and MERIS sensor data are not sufficiently representative of global chl values because they can only resolve larger lakes, which generally have lower chl concentrations than lakes of smaller surface area. Our new methodology utilizes the 300-m-resolution MERIS Full Resolution Full Swath (FRS) global data set as input and does not rely on the land mask used to generate standard NASA products, which masks many lakes that are otherwise resolvable in MERIS imagery. The new method produced chl concentration values for 78,938 and 1,074 lakes in the Northern and Southern Hemispheres, respectively. The accuracy of the MERISderived values was assessed by comparison with temporally near-coincident and globally distributed in situ measurements from the literature (n = 185, RMSE = 9.39, R2 = 0.72). This represents the first global-scale dataset of satellite-derived chl estimates for medium to large lakes.

Publisher's Statement

© 2015 The authors.

Publication Title

IAGLR 58th Annual Conference on Great Lakes Research