An Examination of ENSO’s Effect on the Monthly and Seasonal Climate of Hong Kong from a Statistical Perspective

摘要

This study aims to examine the effect of El Nino and La Nina on the monthly and seasonal climate of Hong Kong against the ENSO-neutral situation from a statistical perspective. Monthly and seasonal temperature and rainfall of Hong Kong and monthly number of tropical cyclones (TCs) coming within 500 km of the city over the 59-yr (1950-2008) period are examined under three ENSO situations, namely El Nino, La Nina, and ENSO-neutral. It is found that, compared with the ENSO-neutral situation, El Nino tends to be associated with wetter winter (December-February) and spring (March-May) while La Nina tends to be associated with cooler autumn (September-November) and winter. El Nino tends to be associated with a later start of the tropical cyclone season of Hong Kong while La Nina tends to be associated with more TCs coming within 500 km of Hong Kong in August-October. It is also found that, for April and June-December, although the monthly number of TCs coming within 500 km of Hong Kong during El Nino is generally lower than that under the ENSO-neutral situation, the difference is not statistically significant based on the current data sample size.