Over the years,the Hong Kong Observatory has carried out scientific studies to evaluate the observed climate trends and project the future climate in Hong Kong.Analysis of the meteorological observations at the observ...Over the years,the Hong Kong Observatory has carried out scientific studies to evaluate the observed climate trends and project the future climate in Hong Kong.Analysis of the meteorological observations at the observatory＇s headquarters in Tsim Sha Tsui since 1885 reveals that the temperature rise in Hong Kong during the past 124 years is in accord with the global rising trend.The accelerated rising trend in the mean temperature in last few decades may be attributed to the anthropogenic influences,especially urbanization.A similar increasing trend is also observed for rainfall.Other observations such as increasing cloud amount and decreasing total global solar radiation are all consistent with the global trend.Studies of past occurrences of extreme temperature and rainfall have also been carried out.The results indicate that cold episodes have become rarer while very hot days and heavy rain events are becoming more frequent.The observatory also makes use of the data from the Fourth Assessment Report（AR4） of the Intergovernmental Panel on Climate Change（IPCC） and employs statistical downscaling techniques to carry out projections of temperature and precipitation in the 21st century.It is found that the rise in temperature in Hong Kong will be slightly higher than the global mean in the 21st century.The annual rainfall in Hong Kong is also expected to rise by the end of the 21st century,so is its year-to-year variability.展开更多
The possible changes in the frequency of extreme temperature events in Hong Kong in the 21st century were investigated by statistically downscaling 26 sets of the daily global climate model projections （a combination...The possible changes in the frequency of extreme temperature events in Hong Kong in the 21st century were investigated by statistically downscaling 26 sets of the daily global climate model projections （a combination of 11 models and 3 greenhouse gas emission scenarios, namely A2, A1B, and B1） of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The models’ performance in simulating the past climate during 1971–2000 has also been verified and discussed. The verification revealed that the models in general have an acceptable skill in reproducing past statistics of extreme temperature events. Moreover, the models are more skillful in simulating the past climate of the hot nights and cold days than that of the very hot days. The projection results suggested that, in the 21st century, the frequency of occurrence of extremely high temperature events in Hong Kong would increase significantly while that of the extremely low temperature events is expected to drop significantly. Based on the multi-model scenario ensemble mean, the average annual numbers of very hot days and hot nights in Hong Kong are expected to increase significantly from 9 days and 16 nights in 1980–1999 to 89 days and 137 nights respectively in 2090–2099. On the other hand, the average annual number of cold days will drop from 17 days in 1980–1999 to about 1 day in 2090–2099. About 65 percent of the model-scenario combinations indicate that there will be on average less than one cold day in 2090–2099. While all the model-emission scenarios in general have projected consistent trends in the change of temperature extremes in the 21st century, there is a large divergence in the projections between difierent model/emission scenarios. This reflects that there are still large uncertainties in the model simulation of the future climate of extreme temperature events.展开更多
文摘Over the years,the Hong Kong Observatory has carried out scientific studies to evaluate the observed climate trends and project the future climate in Hong Kong.Analysis of the meteorological observations at the observatory＇s headquarters in Tsim Sha Tsui since 1885 reveals that the temperature rise in Hong Kong during the past 124 years is in accord with the global rising trend.The accelerated rising trend in the mean temperature in last few decades may be attributed to the anthropogenic influences,especially urbanization.A similar increasing trend is also observed for rainfall.Other observations such as increasing cloud amount and decreasing total global solar radiation are all consistent with the global trend.Studies of past occurrences of extreme temperature and rainfall have also been carried out.The results indicate that cold episodes have become rarer while very hot days and heavy rain events are becoming more frequent.The observatory also makes use of the data from the Fourth Assessment Report（AR4） of the Intergovernmental Panel on Climate Change（IPCC） and employs statistical downscaling techniques to carry out projections of temperature and precipitation in the 21st century.It is found that the rise in temperature in Hong Kong will be slightly higher than the global mean in the 21st century.The annual rainfall in Hong Kong is also expected to rise by the end of the 21st century,so is its year-to-year variability.
文摘The possible changes in the frequency of extreme temperature events in Hong Kong in the 21st century were investigated by statistically downscaling 26 sets of the daily global climate model projections （a combination of 11 models and 3 greenhouse gas emission scenarios, namely A2, A1B, and B1） of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The models’ performance in simulating the past climate during 1971–2000 has also been verified and discussed. The verification revealed that the models in general have an acceptable skill in reproducing past statistics of extreme temperature events. Moreover, the models are more skillful in simulating the past climate of the hot nights and cold days than that of the very hot days. The projection results suggested that, in the 21st century, the frequency of occurrence of extremely high temperature events in Hong Kong would increase significantly while that of the extremely low temperature events is expected to drop significantly. Based on the multi-model scenario ensemble mean, the average annual numbers of very hot days and hot nights in Hong Kong are expected to increase significantly from 9 days and 16 nights in 1980–1999 to 89 days and 137 nights respectively in 2090–2099. On the other hand, the average annual number of cold days will drop from 17 days in 1980–1999 to about 1 day in 2090–2099. About 65 percent of the model-scenario combinations indicate that there will be on average less than one cold day in 2090–2099. While all the model-emission scenarios in general have projected consistent trends in the change of temperature extremes in the 21st century, there is a large divergence in the projections between difierent model/emission scenarios. This reflects that there are still large uncertainties in the model simulation of the future climate of extreme temperature events.
