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Regional modelling of climate and extremes in southeast China
Laurent Li(1), Weilin Chen(2) and Zhihong Jiang(2)
(1) Laboratoire de Météorologie Dynamique, CNRS/IPSL, Université Paris VI, France, li@lmd.jussieu.fr
(2) Nanjing University of Information Science and Technology, Jiangsu Key Laboratory of Meteorological Disaster, China
A variable-grid atmospheric general circulation model,
LMDZ, with a local zoom over southeast China is used as a
traditional regional model to investigate climate changes in
terms of both mean and extremes. This regional version of
LMDZ can also be interactively coupled to the global
version of LMDZ in a two-way nesting manner.
Two time slices of 30 years are chosen to represent
respectively the end of the 20th century and the middle of
the 21st century. The boundary conditions were taken from
the outputs of three global coupled climate models. An
evaluation of the simulated temperature and precipitation for
the current climate shows that in general LMDZ reproduces
well the spatial distribution of mean climate and extremes in
southeast China, but the model has systematic cold bias in
temperature and tends to overestimate the extreme
precipitation.
Scenario results show that in all seasons there is a
significant increase for mean, maximum and minimum
temperature in the entire region, associated with a
decrease in the number of frost days and with an increase
in the heat wave duration. The magnitudes and main
spatial patterns of the changes in temperature extremes
show a quite good consistency among the three global
scenarios. A warming environment also gives rise to
changes in extreme precipitation events. Precipitation
extremes increase over most of southeast China, in a quite
consistent manner among the three global scenarios
Fig. 1: Annual-mean precipitation rate (mm/day) in the global model (left), in the regional model driven by the global model
(middle), and in the regional model operated interactively with the global model (right).
Fig.2: As in Fig.1, but for changes of precipitation (2050-2000).