Spatio-temporal analysis of precipitation, temperature and drought from 1985 to 2020 in Penang, Malaysia

This study aims to analyze the spatial and temporal variability of precipitation, temperature and drought in Penang from 1985 to 2020. The trend and magnitude changes in climate series were tested using the Mann-Kendall test and Sens' slope methods. A significant increasing trend of annual precipitation was detected in the middle and northern parts of Penang Mainland by 21.38 and 35.01 mm/decade. Annual mean maximum temperature increased significantly on Penang Island and the middle of Penang mainland at the rates of 0.25 and 0.34 degrees C/decade, while annual mean minimum temperature increased significantly for all stations from 0.36 to 0.52 degrees C/decade, showing increases of warm nights in the past few years. Extreme drought events (SPI-3> -2) over Penang were mostly occurred during the strong El Nino years, e.g. 1988-1989, 1997-1998, 2010-2011 and 2014-2016. The number of drought events is higher during the 2001-2010 (4-11 events) period as compared to the 1991-2000 (6-9 events) and 2011-2020 (7-8 events). Interestingly, the 2011-2020 period tends to have a shorter drought duration, but more intense droughts have been observed, particularly on Penang Island and the northern and southern parts of Penang Mainland.