The changing extreme values of summer relative humidity in Tarim basin

Abstract:

As one of the driest regions in China, the Tarim Basin, with a desert in its center, lacks water all year round. Relative Humidity here not only matters with the formation of dew and survival of plants and insects in the desert, but also has a large impact on the maintenance of the highway and development of oil and natural gas resources. According to observations of the Tarim Basin, the annual cycle of relative humidity shows that relative humidity in summer is much lower than that in winter, which means that summer is the driest and hottest season. However, summertime also has the highest frequency of extreme water events in the Tarim Basin. In order to understand the contribution of water vapor and temperature in extreme relative humidity events, we used quantile regression to quantify the extreme changes in summer relative humidity during the past decade, based on the data from 19 observation stations in the Tarim Basin. The results showed that the Tarim Basin has shown a trend of getting wetter in the past ten years, and the value of the 95th percentile has increased over years, which means that the maximum value of extreme events has increased, while the minimum value has not changed significantly. To further explore the reasons for the increase in maximum events, we found that such events often occur with specific weather events with increasing frequency. During the process, the ground cools and the pressure increases, and rainfall increases. In the development of this weather system, the contributions of water vapor pressure and temperature are both important. This decadal-scale variability in relative humidity extremes in this specific region is not consistent with the overall prediction for drier land areas with climate change, although the timescale is not one over which it would be possible to detect a forced trend.