Remote sensing retrieval of inorganic suspended particle size in the Bohai Sea

Abstract

In situ data set in the Bohai Sea of China was collected to test a previous model for surface water inorganic suspended particle size developed by Bowers et al. Based on this, a simple empirical model was then established for estimating median particle size in the Bohai Sea. The median inorganic suspended particle size was retrieved from ratio of green (560nm) to red (665nm) band. The model produced retrieval of particle sizes which are in good agreement with in situ measurements with the average percent difference of 27.0% (N=40, R2=0.55) and root mean squared deviation of 4.311μm. This model was quite insensitive to input noises. Then the model was applied to MERIS Level 2 data and MODIS Level 3 data (monthly climatology) to analyze the spatio-temporal pattern and seasonal variability of inorganic suspended particle size in the Bohai Sea. The size of inorganic suspended particles was expected to be related to water turbulence. Wind was idendified as an important influencing factor of particle size distribution. There was an onshore to offshore gradient in inorganic suspended particle size in the Bohai Sea. A significant seasonal cycle exits in particle sizes (large in summer and small in winter). More independent dataset was needed for further research.