An Analysis Of Change Trends And Risk Prediction In Extreme Temperature And Economic Growth In Nanjing

Based on the daily data of temperature from1951to2011in Nanjing city (China), this paper concretely analyzes the characteristics of the changes in extreme temperature, and explores the relationship and the change points between the time series of extreme temperature and Nanjing GDP, also predicts the risk of extreme low and high temperature occurrence in Nanjing of2012, using the methods of linear trend analysis, grey relational model and grey weighted Markov model, respectively. Temperature factors involved in this paper include nine categories, which are average temperature, average maximum temperature, average minimum temperature, extreme high temperature, extreme low temperature, frequency of extreme high temperature, frequency of extreme low temperature, days of high temperature and days of low temperature.(1) Trend analysis on time series of Nanjing extreme temperature during1951-2011: Extreme temperature indices are constructed based on the daily data of maximum, minimum and average temperature of Nanjing, in order to analyze the trends of extreme temperature over the61years. Results show that all the three temperature series are on the increase, with most significantly after the1990s, and the growth margin of annual minimum temperature is obviously larger than that of maximum temperature. Besides, seasonal trends of annual average maximum and minimum temperature are on the rise except the average maximum temperature in summer. Meanwhile, trend of extreme high temperature is stable while extreme low temperature is significantly upward. In addition, decreasing trends about frequency of extreme high temperature and days of high temperature is not evident but stable, however, these two indicators of low temperature is significantly on the decrease. So, it is easy to find that all temperature indices of Nanjing city are characterized of increase trend.(2) Relationship and change point research on the time series of extreme temperature and Nanjing GDP over the period of1951-2011:Relation between the series of extreme temperature and GDP growth rate is found strong in this paper. However, the most relevant factors are the days of high and low temperature, with correlation degree being0.7819and0.7798. That is, these two factors hold the most significant relationship with GDP, which means that the local short-term climate change is sensitive to the economic development. Without a doubt, the climate change also has influence on the economic development in turn. Finally, change points between the meteorology factors (average temperature, extreme temperature and frequency of extreme temperature) and Nanjing GDP growth rate are consistent with the trends, meaning a close relationship between economic development and climate change does exist in Nanjing.(3) Risk prediction of extreme high and low temperature occurrence in the year of2012on the basis of the Nanjing daily observation data from1951to2011:By dividing different duration of extreme high temperature and low temperature, weighted high and low temperature indices are built through the models of weighted Markov and grey weighted Markov prediction. With the above steps, the risk of the extreme high and low temperature occurrence in Nanjing can be predicted. As a result, risk states of the extreme high and low temperature of Nanjing in2012are obtained as a common situation, which means the probability of extreme temperature occurrence is quite small.