Changes in Local Growing Season Indices in Shanghai Due to Urbanization during 1873–2013
XIA Jiang-Jiang;YAN Zhong-Wei;XIONG Zhe;Key Laboratory of Regional Climate-Environment for East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences;
The contribution of urbanization to the changes in growing season indices(e.g., the start date of the growing season, Ds) in Shanghai, eastern China, for the period 1873–2013 is assessed. The urban-related Ds advancement(referred to as the urbanization contribution, UC) is reconstructed based on the changing urban-land fraction within a grid box around Shanghai for 1873– 2013. After removing the UC from the raw Ds time series, the secular trend(ST) representing the long-term climatic warming and multidecadal variability(MDV) representing an oscillatory component with a period of several decades are obtained by using the Ensemble Empirical Mode Decomposition(EEMD) method. Results show that the UC is comparable with the contribution of the ST for the period 1873–2013, when Ds exhibits an advancing rate of about 0.44 days per decade. MDV plays an important role in regulating changes in Ds on the decadal timescale, e.g., with a contribution of about 56.1% for 1981–2013.