Joint probability of drought encounter among three major grain production zones of China under nonstationary climate

Abstract

Better understanding for the likelihood of drought occur in the main grain production zones of China is key to minimize the risk for food security, especially in a changing climate. In an attempt to encompass the climate variability in the assessment of drought, a nonstationary standardized precipitation index (NSPI) was established for three major grain production zones (Songnen Plain (SN), North China Plain (NC), and Sichuan Basin (SC), hereinafter referred to GPZs) by means of using the climate indices as covariates. Then three commonly used Archimedean copulas (i.e., Clayton, Frank, and Gumbel-Hougaard) were adopted to determine the joint drought probability model. Using the joint probability distribution, the risk of drought in different degree occurring among the three GPZs, conditional joint probability, and conditional return period of different drought combinations of GPZs were analyzed. The results show that NSPI reflected the drought conditions well in three GPZs, and the copula-based joint probability distributions of different drought situations among the three GPZs were reasonable. For the situation of droughts encounter in two GPZs, synchronous droughts in different degree are more prone to encounter in NC & SC, and the conditional joint drought probability (return period) is also higher (lower) in the combination of SC and NC. For the situation of droughts encounter in three GPZs, the probability of synchronous droughts in the three GPZs is decreasing with increase of drought degree. If a specifically drought (NSPI ≤ -1) occurred in two GPZs, the conditional joint drought probability is highest in NC, then followed by SC, and SN. The findings of this study could provide important implications of decision-making for food security.