The Spatial-temporal Dynamics Of Late Spring Coldness In Jiangsu And It Influence On Agriculture And Forestry

Late spring coldness,as one of the typical meteorological hazards,has influenced the development of agriculture and forestry under climate change.In this research,the late spring coldness strength index was calculated by meteorological data from 60 meteorological stations in Jiangsu from 1960 to 2014.EOF analysis,low-pass filter,Mann-Kendall test,wavelet analysis,and other statistical analysis techniques were used to study the occurrence rules of late spring coldness and the spatial and temporal dynamics in Jiangsu,The Results showed that;(1)In recent 55 years,the occurrence frequency has a Slightly rising trend,and the spatial distribution of late spring coldness is shown as:Subei>Suzhong>Sunan.(2)Severe late spring coldness is concentrated on 1960s,and there is just slight or none late spring coldness happened in Jiangsu after 2000.The difference between the late spring coldness of the north part and the south part of Jiangsu is significant,and the variation in the south part is fiercer than the north part.The late spring coldness strength index of Jiangsu increases in 1970s,1980s,and 1990s,while the other time period has a decreasing trend.The late spring coldness of different regions in Jiangsu all have two cycle periods,and the cycle periods of entire Jiangsu is 5 years and 20 years.The late spring coldness in Jiangsu is positively correlated with Atlantic-European W circulation in last winter,and is negatively correlated with polar vortex intensity in this spring.(3)The main landscape type of Jiangsu is cropland,and the transfer of different landscapes in different regions is not significant.The average NDVI has an increasing trend in different regions of Jiangsu,of which the trend in late April is the most significant.The NDVI of crop land and forest also have an increasing trend on average,and the NDVI variation in forest is more significant than crop land.(4)The late spring coldness has influence on crop land and forest from March to April,with negative correlation in some regions.However,there are still some regions with positive correlation insignificantly,owing to terrains,other meteorological factors,and human factors.What’s more,the spring late coldness has significant lag effect.The effect of the late spring coldness on crop land and forest in early and middle May is more significant than other time periods,which has shown that the spring late coldness has significant lag effect.What’s more,the influence of the spring late coldness on cropland is stronger than forest,which is related to the resilience of two ecosystems.