Temporal Record of Methane Concentration over Pakistan by Using Satellite Observations

Abstract

The rapidly changing global climate since the mid-20th century is attributed to the observed increase in anthropogenic greenhouse gas (GHG) emissions. Pakistan is ranked 12th among the nations that are most susceptible to the extreme weather events such as heavy floods and droughts etc. In order to implicate the impacts of enhanced greenhouse gas concentrations over Pakistan, a spatiotemporal analysis of concentration is conducted by using satellite observations from SCIAMACHY. The Iterative maximum a posteriori (IMAP)-DOAS algorithm is used to retrieve column densities from Nadir observations of SCIAMACHY instrument. This study focuses mainly on long term spatial and temporal variations in atmospheric Methane over Pakistan during the time period of 2003–2011. Temporal analysis indicated a gradual increase of 2.67% in CH4 concentration over Pakistan during the study period (2003 - 2011). Rice cultivated regions of Punjab and Sindh consistently showed high concentrations. Satellite observations exhibited a constant seasonal variability in CH4 concentrations over Pakistan, being highest in summer and lowest in winter except for the year 2010. An anomalous shift in seasonal cycle of Methane is observed as a repercussion of the devastating nationwide floods of 2010, which resulted in a loss of about 0.5 Million Hectares of Rice cropland.