Latitudinal patterns of climatic variables and influence of local topography on climatic variables in the dry valleys of southwestern China

Climate is a key factor to determine the pattern of ecosystems; however, the latitudinal patterns of climatic variables in the arid and semi-arid areas remain largely unclear when compared to humid areas. The topography of the dry valleys of southwestern China plays an important role in the formation of climate. However, its impact on the climate remains qualitative. In this study, eight climatic variables from 12 meteorological stations were analyzed to explore their latitudinal patterns in the wet and dry seasons from 1961 to 2019. We also quantified the effects of local topography (RH10) on the climatic variables. The results were as follows: sunshine duration, total solar radiation, average temperature, and evaporation decreased significantly, and wind speed increased significantly with increasing latitude in the annual, wet, and dry seasons (P<0.001). Relative humidity and precipitation decreased significantly with increasing latitude in the wet season (P<0.001), and no obvious change pattern was observed in the dry season. Aridity index significantly decreased (toward dryness) with increasing latitude in the wet season and increased in the dry season (P<0.001). Wind speed had a significantly positive relationship with topography (RH10) (P<0.01), whereas precipitation and aridity index were negatively associated with topography in the wet season and positively associated with topography in the dry season. Dryness was positively associated with RH10 in the wet season, and negatively in the dry season. The results of our research could provide new perspectives for understanding the relationship between topography and drought in the dry valleys of southwestern China.