Affected by warming, precipitation in the TB has a large interannual and spatial variability. In this study, we analyzed the trends in a set of daily precipitation indices for the TB between 1961–2019. Changes in the daily amount and distribution of precipitation have important implications because agriculture and water supply are often limited by water availability in the study area, and heavy rainfall events constitute a major natural hazard in the region.
In the past 58 years, although the annual mean precipitation and precipitation days in the study area has increased, indicating a change in the precipitation intensity in the study area. Therefore, suitable water planting is still needed to vigorously develop water-saving agriculture, strengthen drought monitoring and early warning, strengthen emergency drought prevention and disaster avoidance technology, and improve agriculture in Northwest China to adapt to drought.
The spatial and temporal differences found in the evolution of precipitation indices have important implications for water management and risk assessment in the region. Thus, an increased precipitation is observed in the region, and increasing surface air temperatures can lead to an enhanced melting of snow and glaciers in the surrounding mountains of the TB, causing extreme runoff events such as floods (Peng et al. 2014). Climate change has resulted in an increase in the streamflow at the headwaters of the Tarim River, but anthropogenic activities, such as over-depletion of the surface water, have resulted in a decrease in the streamflow at the lower reaches of the Tarim River (Chen et al. 2005).
Rainfall, snowfall, and rain and snow are the three important attributes of precipitation events. The three contain important information about the occurrence and development of precipitation. In-depth studies of these three attributes can significantly deepen the understanding of precipitation itself, the physical mechanism behind it, and the climate background. From a holistic perspective, rainfall, snowfall, and rain and snow amounts are not independent. If these three are separated and analyzed independently, although some important information about precipitation can be obtained, this information is still only based on a single feature of precipitation, frequency, or intensity and only contains information about a certain aspect of the precipitation event. It also does not contain the overall information of the rainfall, snowfall, rain, and snow events. Hence, it is impossible to grasp the characteristics of changes in precipitation types as a whole. If there is no significant change in precipitation in an area, but the intensity of rainfall increases and the frequency of extreme rainfall increases, the possibility of flooding increases. Therefore, it is necessary to study the in-depth changes for at least two attribute characteristics of rainfall events of different intensities, rainy days, and rain intensity from a systematic perspective.
The determination of different rainfall patterns and impact diagnosis rainfall includes process rainfall, convective rainfall, and topographic rainfall. Convective rainstorms are not only affected by natural factors but also by strong local human activities and urbanization (Ai et al. 2009). It can be seen that different rain patterns characterize different rainfall processes, and the physical processes and formation mechanisms behind them are also different. Therefore, the determination of different rain patterns in rainfall research is of great significance to the study of different rainfall intensities and their contribution to total rainfall.
This paper analyzes the spatial distribution characteristics of different levels of precipitation, precipitation days, precipitation intensity, and contribution rate in the TB without discussing its influencing factors. In addition, because of the vast area of the TB, the distribution of meteorological stations is scattered, especially, in the Bazhou area in the southeast, where the distribution of stations is sparse. Hence, the spatial distribution of the precipitation revealed is not detailed enough. In addition to topography, geography, and other factors, it is necessary to analyze the corresponding atmospheric circulation patterns when various levels of precipitation occur in the TB, especially, the corresponding weather system, which still needs to be studied further.