Article Title :
Exploring Temporal Rainfall Variability and Trends Over a Tropical Region Using Tropical Rainfall Measurement Mission (TRMM) and Observatory Data
5 (2021)
56-71
TRMM , Rainfall Variability , Indian Monsoon , Climate variability
Kerala is the gateway of the Indian southwest monsoon. The Tropical Rainfall Measurement Mission (TRMM) rainfall data is an efficient approach to rainfall measurement. This study explores the temporal variability in rainfall and trends over Kerala from 1998-2019 using TRMM data and observatory data procured from India Meteorological Department (IMD). Direct comparison with observatory data at various time scales proved the reliability of the TRMM data (monthly, seasonal and annual). The temporal rainfall converted by averaging the data on an annual, monthly and seasonal time scale, and the results have confirmed that the rainfall estimated based on satellite data is dependable. The station wise comparison of rainfall in monsoon season provides satisfactory results. However, estimation of rainfall in mountainous areas is challenging task using the TRMM. In the basins of humid tropical regions, TRMM data can be a valuable source of rainfall data for water resource management and monitoring with some vigilance. In Kerala, the study found an insignificant increase in the southwest monsoon and winter season rainfall during last two decades. The rainfall over Kerala showed uncertainty in the distribution of monthly, seasonal and yearly time scales. This study provides a preview of recent weather patterns that would enable us to make better decisions and improve public policy against climate change.
TRMM satellite estimations are compared with IMD station data on a yearly, monthly, and seasonal basis; they produce a better result, making them a suitable replacement for hydro-meteorological, climatological distribution and frequency studies with caution due to under- and overestimation.
The station wise comparison of monsoon season rainfall provides satisfactory results. However, obtaining rainfall amounts in mountainous areas was challenging using the TRMM.
Increase in southwest monsoon rainfall between 1998 to 2019, whereas the post-monsoon season is decreasing. The increase in rainfall is more noticeable during July to September, with a statistically insignificant trend.
Annual rainfall increased to a statistically insignificant level from 2009 to 2019.
Over recent decades, the consistency of rainfall over particular months and seasons has decreased, indicating an increase in rainfall uncertainty.
Sharma, S., Kolte, S. S., Singh, A. K. and Gairola, R. M., 2012. Estimation of precipitation variability from satellite data over Ganga basin, India. Presented at The 1st International Space Conference 2012 at Ahmedabad, Gujarat, 30 Nov-1 Dec, 2012.
