Influence of air temperature and interrelationship with greenhouse gases (CO2 2 and CH4) 4 ) over Iraq using AIRS data

Global and regional observations of air temperature (AT) and specific atmospheric greenhouse gases (GHGs) such as methane (CH4) 4 ) and carbon dioxide (CO2) 2 ) are required for a variety of applications, including constraining global or regional estimates of their significant impacts on the climate system. The present study employs Atmospheric Infrared Sounder (AIRS) -Level3 monthly products for AT, CH4, 4 , and CO2, 2 , at two standard pressure levels (925 and 500 hPa) over Iraq during 2010-2016. Both CO2 2 and CH4 4 shows significant seasonal variation, with maximum (minimum) CO2 2 observed in June (October), while CH4 4 recorded three maximum peaks during April, August, and November, and a minimum in February. CH4 4 shows a negative correlation during winter (DJF), spring (MAM), summer (JJA), and autumn (SON) with correlation coefficients (R)-0.627,-0.734,-0.491, and-0.688, respectively. The P-value is below 0.05 (4.14 x 10-15,-15 , 2.13 x 10-- 22 , 1.1 x 10-- 8 , and 5.2 x 10-19)-19 ) for the four seasons, indicating a negative linear relationship. CO2 2 shows a low negative correlation in DJF and SON, and a low positive correlation in MAM and JJA seasons, with R values equal to-0.315,-0.221, 0.059, and 0.079, for DJF, SON, MAM and JJA seasons, respectively. The P-value was greater than 0.05 (0.061, 0.728, 0.647, and 0.195) for the four seasons, respectively, indicating a nonlinear relationship with AT. The monthly averaged time-series for CH4 4 and CO2 2 shows an evident increase, with an annual average increase of 1.81% (4.75) ppbv/year and 3.31% (1.84) ppm/year, respectively. Analysis reveals that the major sink and sources for CH4 4 are the presence of hydroxyl (OH) radicals and vegetation, whereas the major sources for CO2 2 are anthropogenic emissions, burning fossil fuels, and land-use change. The satellite observations of AIRS can efficiently show the spatiotemporal variations of air temperature versus CH4 4 and CO2 2 for the study area.