Seasonal cycle is the crucial intraannual climate pattern to be observed in global and regional agricultural practice.Under global warming,the global surface has witnessed a significant increase in temperature over nearly half a century.As a result,various parameters associated with surface air temperatures,such as the lengths,start dates,and end dates of the four seasons,also changed dramatically.This study examined the following aspects:1)It summarized the three types of season definition methods,including astronomical,meteorological,and phenological methods;absolute and relative temperature threshold methods;and other methods characterized by regional geographic factors and specific weather phenomena.2)This study conducted an analysis on the long-term seasonal variation characteristics in the lower-middle reaches of the Yangtze River and the South China region during 1961-2015,using different seasonal division methods based on air temperature and analyzing the characteristics and differences in summer length calculated by different temperature indices.It also reviewed the characteristics of seasonal length changes in historical periods defined by different indicators and the future projected trends,and summarized the key reasons for seasonal length changes.3)This study evaluated the advantages and disadvantages of each seasonal division method from their fields of application and spatial applicability.Future research is prospected from the possible impact of data bias,the development of a commonly applicable index,and the mechanism of change under climate warming.The results of this study have clarified the differences of seasonal division methods,as well as the characteristics and causes of seasonal changes.This not only is beneficial for guiding agricultural production,but also provides reliable scientific information for addressing the climate change issue.
seasonal divisionseason lengthchangescauses of changeglobal warming
NETL
NSTL
万方数据
维普
