The Sensitivity of DTR to the Increased CO2 over Mid-latitude Semi-dry Regions

The rationale for this study lies in the fact that the mid-latitude regions are largely affected by the global and regional scale circulation changes. Moreover, earlier studies emphasize that the variation in atmospheric concentration of heat-trapping gases, cloud amount and moisture contents produce substantial regional climatic changes. Therefore, it is of significant practical importance to analyze the sensitivity of midlatitude regions to anthropogenic forcing, especially, the CO2 radiative forcing. This study assesses the role of CO2 radiative forcing in causing asymmetric diurnal changes over the mid-latitude semi-dry region using an idealized experiment conducted by single column (1-D) RadiativeConvective Model (RCM) of the diurnal cycle. The model is capable enough in highlighting the main features responsible for the observed diurnal asymmetry in the ground temperature. A significant decrease in the Diurnal Temperature Range (DTR) is observed in this region under doubled CO2 forcing. The amount of thermal radiation trapped by CO2 forcing in the presence of water vapors plays a key role in surface temperature changes and resultant decreasing of the DTR. It is further found that CO2 induced climatic feedbacks are equally important in producing diurnal asymmetry. To better understand the complete picture of the DTR variability, one needs to explore all the possible forcing and feedbacks such as caused by aerosols, water vapors and cloud amount along with their distribution in the atmosphere.