Assessment of candidate distributions for SPI/SPEI and sensitivity of drought to climatic variables in China

Abstract

Drought occurs more frequently in the context of climate change and threatens water security worldwide. An appropriate fitting distribution is crucial for accurately identifying drought using drought indices. Here, seven two-parameter distributions (Gamma, Gumbel, Logistic, Log-Logistic, Log-normal, Normal, and Weibull) and four distributions (general logistic, generalized extreme value, Normal, and Pearson Type III) are applied to calculate the standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI), respectively, to choose the most appropriate fit for the 541 stations in China. The results show that, in most cases, Gamma and general logistic were the best distributions for SPI and SPEI, respectively. Nevertheless, we noted that Pearson Type III and generalized extreme value also fit the SPEI series well, indicating the importance of distribution fitting assessment for various regions. The annual and seasonal drought evolutions across China were clarified, with drought decreasing significantly in western Northwest China (annually and each season), northern North China (spring and winter), the Tibetan Plateau (spring), and the lower reaches of the Yangtze River (winter) and increasing mainly in South China (spring) and western South China (summer and autumn). The intensity, duration and severity of light, moderate, and severe drought were also detected; the results suggest that drought in China is mainly concentrated around the changes in light and moderate drought. Additionally, we assessed the sensitivity of drought evolution to various meteorological variables. The most sensitive variable in South China, North China and the Tibetan Plateau is precipitation, followed by wind speed, temperature, relative humidity, and sunshine duration; in Northwest China, the order is wind speed, precipitation, temperature, relative humidity, and sunshine duration. Furthermore, the correlation results also indicate that the drought evolution is affected by the multivariate ENSO index, while the influencing characteristics are different in various seasons and regions. The results in this paper contribute to drought mitigation and the effective utilization of water resources in China.

Continuous Wetting on the Tibetan Plateau during 1970–2017

“…In this study, we revisited the changes in drought characteristics across the TP for the period of 1970-2017 using the SPEI based on the highly available and abundant records from national meteorological stations. Our analysis result confirms an overall wetting trend in the growing season on the TP since 1970, which corresponds with previous studies based on observational station data using the SPI/SPEI [25,29] and aridity index [27,28]. However, this finding is not in line with the results based on the sc-PDSI calculated with global reanalysis data sets [23,24].…”

“…Changes in meteorological drought are generally associated with anomalies in precipitation, temperature, and evaporation. The opposite trends in meteorological drought between the TP and its surrounding area were mainly related to the opposite change trends in precipitation [13,[27][28][29]58].…”

“…The TP, located in Southwest China (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40) • N and 76-104 • E), encompasses an area of approximately 2.57 × 10 6 km 2 with an average elevation of higher than 4000 m above sea level [35], which leads to the generation of a unique climate regime ( Figure 1). The temperature in the Southeastern TP is relatively warmer, while that in the Northwestern TP is extremely cold.…”

“…The question of whether the TP is becoming wetter or drier has attracted much attention; however, recent literature has presented inconsistent conclusions. For example, several studies using the sc-PDSI found that the TP exhibited a significant drying trend [23], especially in the Northern TP [24], whereas other studies showed that the TP experienced wetting [13,[25][26][27][28] and exhibited a decrease in drought intensity [29]. Additionally, the drought intensity on the TP exhibited obvious inter-decadal variation [30]; however, the variation characteristics of the drought intensity in each time interval remain seldom investigated.…”

Analysis of Agricultural Drought Risk Based on Information Distribution and Diffusion Methods in the Main Grain Production Areas of China

“…Zeng ZQ et al concluded that the main meteorological reason for the high frequency of extreme drought was the combined effect of abnormal decreases in rainfall and continued increases in temperature [29]. Wang HJ et al indicated that drought in China was mainly concentrated around the changes in light and moderate drought and wind speed, precipitation, temperature were the most sensitive variable in northwest China, while in south China it was precipitation, followed by wind speed, temperature, relative humidity, and sunshine duration [44]. So we could infer that in the Chinese conditions, the lack of precipitation in the north has a stronger drought effect than the increase in temperatures towards the south.…”