SUSPENDED PARTICULATE MATTER DYNAMICS ALONG THE LOUISIANA-TEXAS COAST FROM SATELLITE OBSERVATIONS

Abstract

Time-series satellite derived suspended particulate matter (SPM) concentrations were used to examine seasonal patterns of distribution and dominant scales of variability along the Louisiana-Texas coast influenced by the discharge from the Mississippi and Atchafalaya Rivers. Monthly averages of Sea-viewing Wide Field-of-view Sensor (SeaWiFS) derived SPM of the Louisiana-Texas coast during 2005 indicated strong seasonal variability associated with river discharge that influenced the structure and areal extent of the Mississippi and Atchafalaya River plumes. The Atchafalaya River, a major distributary of the Mississippi River discharges significant amounts of sediment into the Atchafalaya Bay and on the inner-continental shelf. Dominant scales of SPM variability were examined by applying wavelet analysis to a 10-year time series (September 1997 to December 2008) SeaWIFS data across a transect on the inner shelf and off the Atchafalaya Bay. A strong seasonality with largest magnitude in SPM variability in fall/winter was associated with cold front passages and minimum in summer. Maxima in interannual SPM variance observed in 1998, 2001, 2003 and 2004 were more likely to occur during years of tropical depression storms and hurricanes followed by elevated river discharge and cold front activity during the fall/winter period that enhanced SPM transport across the Atchafalaya delta.