Please login first
Monsoon Dynamics in the Ganges-Brahmaputra-Meghna Basin
* 1 , 2 , 2 , 3
1  East Carolina University, USA
2  Virginina Tech, USA
3  Kansas State University, USA


A recently funded US National Science Foundation project seeks to investigate monsoon variability within the Ganges-Brahmaputra-Meghna (GBM) river basin as a potential predictor for annual shoreline erosion rates in the lower coastal delta region. Many previous studies have examined the interannual variability of South Asian precipitation either within political boundaries or across large spans of latitudes and longitudes, but few have taken a more hydrologic approach by analyzing the atmospheric-oceanic forcings that lead to precipitation falling only within the GBM basin.  The temporal climate patterns would likely be different from previous studies and are hypothesized to have a more direct effect on outlet discharge and erosion rates. In the present study, mean monsoon precipitation (June-July-August-September) for the 2309 0.25° grid boxes of the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR) was extracted using geospatial methods. A Principal Component (PC) analysis was performed over the period 1983 to 2015. The first PC explains 88.7% of the variance and resembles climatology with the center of action over Bangladesh.  The eigenvector shows a downward trend consistent with studies reporting a recent decline in monsoon rainfall. The second PC explains 2.9% of the variance and concentrates rainfall in the western portion of the basin. The 2nd component has greater temporal variability than the 1st component and an apparent decadal cycle. An analysis of global precipitation indicates that the rainfall patterns obtained within the GBM are localized. Surface and upper-air atmospheric height fields suggest the 2nd PC pattern is forced by a Rossby wave train stemming from the North Atlantic.

Keywords: precipitation, monsoon, Ganges-Brahmaputra-Meghna, GIS, climate variability
Comments on this paper
Rogert Sorí
Dear authors!

It is an interesting work!!!. Just to comment something; despite the low correlations between PCs and SST over the Pacific and specifically the Niño’s regions, there are some authors that assess and discuss a possible relationship. Also, during the rainy season the Bay of Bengal acts as a most important source of moisture for the Brahmaputra River basin (to the northeast of the Ganges); maybe it is the reason of positive (negative) correlations between PC1 (PC2) and SST in this region.

Kind regards.