Spatiotemporal computing of cold wave characteristic in recent 52 years: a case study in Guangdong Province, South China

Based on daily air-temperature data of 86 weather stations in recent 52 years (1961–2012) in Guangdong Province, South China, annual cold wave events in each station were calculated. Then, the spatiotemporal characteristics of cold wave over Guangdong Province were thoroughly analyzed by wavelet transform and other statistical analysis method. The results indicate that: (1) The cold wave frequency gradually decreased from north to south, from inland to coastal area and from highland to lower land showing evident regional variance; if there occurred a large range of cold wave, the temperature fall caused by cold wave would be bigger in southwestern area than in the rest of Guangdong Province; (2) 161 regional cold wave events in total invaded Guangdong in recent 52 years. The cold waves can be classified into three invasion paths: north, northeast and west. Most of cold waves took the north path, and a few of them took the west path only; (3) Based on the influence range, the cold wave can be divided into 4 grades. The climatic characteristic of each grade shows that the larger the range of influence was, the more severe the hazard of cold wave would be; (4) Cold wave whose influence range was smaller than 10 % of provincial area happened almost every year, and the frequency was 1.9 annually; cold wave whose influence range was larger than 50 % happened 13 times in recent 52 years; (5) The intensity of cold wave over Guangdong was declining at the rate of 5.5 station-day per year; it also had an inter-decadal oscillation period of 10–14 years, and an obvious inter-annual oscillation period of 3–4 years before 2000; (6) Cold wave frequency of each month varied significantly, 76 % of which occurred during December to next February; (7) The snow disaster of 2008 had caused great losses to Guangdong agriculture. But according to the criteria of cold wave, only 22 stations (25 %) of Guangdong actually reached the standard of cold wave. Therefore, the cold disaster index should be additionally considered when analyzing the impact of disaster by cold air process, and the relationship between cold wave and cold disaster is worth further research.