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

This study aims to examine the effect of El Ni~no and La Ni~na on the monthly and seasonal climateof Hong Kong against the ENSO-neutral situation from a statistical perspective. Monthly and seasonaltemperature and rainfall of Hong Kong and monthly number of tropical cyclones (TCs) coming within 500km of the city over the 59-yr (1950-2008) period are examined under three ENSO situations, namely El Ni~no,La Ni~na, and ENSO-neutral. It is found that, compared with the ENSO-neutral situation, El Ni~no tendsto be associated with wetter winter (December-February) and spring (March-May) while La Ni~na tendsto be associated with cooler autumn (September-November) and winter. El Ni~no tends to be associatedwith a later start of the tropical cyclone season of Hong Kong while La Ni~na tends to be associated withmore TCs coming within 500 km of Hong Kong in August-October. It is also found that, for April andJune-December, although the monthly number of TCs coming within 500 km of Hong Kong during El Ni~nois generally lower than that under the ENSO-neutral situation, the difference is not statistically significantbased on the current data sample size.