CLIPS Report
January to December 2003
Hong Kong Observatory
Hong Kong, China
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Climate prediction
1.1 A pilot study to examine the feasibility of making seasonal forecasts for Hong Kong,
launched in late 2000, was completed in December 2002. The study demonstrated that
some skills exist in forecasting the annual rainfall and the number of tropical cyclones
affecting Hong Kong in a year.
1.2 After the trials in 2001 and 2002, the Hong Kong Observatory (HKO) started issuing
annual
climate
forecasts
in
2003
on
the
HKO
web
site
at
http://www.weather.gov.hk/wxinfo/season/season.htm.
The probabilities of the
predictant being below, near and above normal are given.
1.3 Quarterly updates on ENSO status were also made available to the public through the
Hong Kong Observatory web site at http://www.weather.gov.hk/wxinfo/climat/enso.htm
to meet the public’s interest on the subject.
2
Research, development and applications
2.1 In November 2000, HKO in collaboration with Experimental Climate Prediction Center
(ECPC) began to adapt a regional climate model (RCM) with a view to providing
guidance for seasonal forecasting on a regional scale. The model is based on the
Regional Spectral Model (RSM) of the National Centers for Environmental Prediction
(NCEP). The model's inner domain has 49x50 grid points centered on Hong Kong.
Horizontal grid resolution is 15 km and there are 18 levels in the vertical. The outer
domain has 21x14 grids with an effective horizontal resolution of T62 and also 18 levels
in the vertical. The time step of integration is 90 seconds. The initial and boundary
data used to force the model come from a subset of the output of the NCEP Global
Spectral Model provided by ECPC.
The model was run once a week with forecasts generated at 6-hour intervals up to 12
weeks ahead since mid 2001. Weekly, monthly and 12-weekly means of temperature,
precipitation and winds were computed from the 6-hourly forecasts using a
time-averaging utility developed in-house.
Extensive experimental runs were conducted in 2003. Model climate for generation of
precipitation and temperature anomaly forecasts were complied for the months of April,
May, July, October and December. Since July 2003, seasonal precipitation and
temperature anomaly forecasts were computed. Preliminary verification indicated that
some skills exists in seasonal forecasting of temperature and precipitation near Hong
Kong, complementing global model outputs from major overseas centres.
Experimental seasonal temperature and precipitation advisories, based on the RCM
output and dynamical products from major centres, were prepared on an experimental
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basis for internal reference.
2.2 Starting from April 2003, monthly climate diagnostic bulletins covering significant
departures from climatological normals were prepared on an experimental basis for
evaluation.
2.3 An outlook for winter temperature for DJF 2003/04 based on a conceptual model and
taking into account results of dynamical forecasts from major centres was prepared and
issued for evaluation.
2.4 A study on climate change in Hong Kong was carried out. Results showed that Hong
Kong has been warming up during the past 118 years, in line with the global warming
trend. In the period 1989 to 2002, the rural areas of Hong Kong have been warming at
a rate of 0.2°C per decade while in the urban areas, the corresponding rise was about
0.6°C per decade. The difference of 0.4°C per decade may be attributed to the effects
of high density urban development. Reduction in visibility, increase in cloud amount
and decrease in global solar radiation in Hong Kong was found and might also be related
to high density urban development. Key findings of the climate change study were
publicized in a briefing for the mass media and a press release issued.
3
Training and coordination
3.1 A series of public lectures on tropical cyclones, the Asian Monsoon, climate prediction
and climate change by invited scientists was organized towards the end of 2003 to
educate the public. Details are given below:
Lecture
Date
Lecturer
El Nino and Asian Climate
18.10.2003
N.C. Lau, Geophysical Fluid
Dynamics Laboratory, NOAA
The East Asian Monsoon
19.10.2003
C.P. Chang, Naval Postgraduate
School, USA
Understanding Typhoon Activity
25.10.2003
J.C.L. Chan, City University of
Hong Kong
Tibetan Plateau and its Relationship 15.11.2003
to Large Scale Circulation in China
G.X. Wu, Chinese Academy of
Sciences
The Science of Climate Change
Y.H. Ding, National Climate
Prediction Center of China
Atmosphere-Biosphere
and Man as a Part
29.11.2003
Interaction 6.12.2003
2
C.Y. Lam, Director of the Hong
Kong Observatory
3.2 A series of seminars on short range climate forecasting and climate change was also
organized for HKO staff. A summary is given below:
Seminar
Date
Keynote speaker
Impact of El Nino on Variability 14.10.2003
of the Global Atmosphere-Ocean
System
N.C. Lau, Geophysical Fluid
Dynamics Laboratory, NOAA
Structure,
mechanisms
and 21.10.2003
effects of the East Asian
Monsoon
C.P.
Chang,
Naval
Postgraduate School, USA
Predicting the Onset of the Asian 14.11.2003
Monsoon
G.X. Wu, Chinese Academy of
Sciences
Climate Change in China
Y.H. Ding, National Climate
Prediction Center of China
1.12.2003
3.3 To promote public awareness on climate change, a number of popular lectures and talks
were also organized by HKO for various organizations and school.
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Plans for 2004
4.1 Review the schemes for predicting annual rainfall and number of tropical cyclones
affecting Hong Kong in a year.
4.2 Conduct more experiments on generating seasonal anomaly forecasts using the RCM.
4.3 Complete a study on regional rainfall trend in Hong Kong.
4.4 Complete a study on sea level change in Hong Kong.
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Publications
5.1 Chang, W.L and K.H. Yeung, 2003, “Seasonal Forecasting for Hong Kong – A Pilot
Study”, Hong Kong Observatory Technical Note No. 104.
5.2 Wu, M.C., W.L. Chang and W.M. Leung, 2003, “Impact of El Nino-Southern Oscillation
(ENSO) Events on Tropical Cyclone Landfalling Activity in the Western North Pacific”,
J. Climate, paper accepted.
5.3 Ginn, E.W.L. and K.Y. Shum, 2003, “Short Range Climate Forecasting at the Hong
Kong Observatory and Application of APCN and Other Web Site Products”,
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Proceedings of APCN Symposium on the Multi-Model Ensemble for Climate Prediction,
Jeju Island, Republic of Korea, 7-10 October 2003.
5.4 Leung, Y.K., K.H. Yeung, E.W.L. Ginn and W.M. Leung, 2004, “Climate Change in
Hong Kong”, Hong Kong Observatory Technical Note No. 107 (being printed).
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