Correlation analyses between downward longwave radiation particulate matters, aerosol optical depth, and metrological variables under non-dusty and cloudless conditions

This study used downward longwave (LW) radiation measurements, air temperature (T), particulate matter (PM) concentrations of fine (PM 2.5) and coarse (PM10) particles, aerosol optical depth (AOD), wind speed (WS), precipitable water vapor (PWV) data from Riyadh, an arid site in central Saudi Arabia, between 2014 2019 to characterize their variations investigate the influence these variables on measured LW under non-dusty, clear sky conditions. The temperature, it was found, attain maximum summer minimum winter. Conversely, PM mean AOD showed spring PWV features increasing trend during spring, summer, fall, whereas a decreasing monthly variation WS shows low values fall winter considerably higher summer. Apart speed, which does not affect radiation, correlation analyses demonstrated that correlates positively with remainder considered variables. strength degree association differ one variable another, having strongest (correlation coefficient = 0.98) followed by 0.69), 0.36 PWV. Similarly, relationships both PM10 PM2.5 had same 0.32. effect meteorological (mainly relative humidity, speed) investigated using regression analyses. results significant positive relationship negative RH.