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Climate change in the Tibetan Plateau: the past and the future'

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Nansen-Zhu International Research Centre, Institute of ... May 4 6, 2009, UCSD, La Jolla, CA. Contents. 1) Introduction. 2) Observed climate change ... – PowerPoint PPT presentation

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Title: Climate change in the Tibetan Plateau: the past and the future'


1
Climate change in the Tibetan Plateau the past
and the future.
Shuanglin Li Nansen-Zhu International Research
Centre, Institute of Atmospheric Physics/CAS

Ice, Snow, and Water Impacts of Climate
Change on California and Himalayan Asia May 4
6, 2009, UCSD, La Jolla, CA
2
Contents
  • 1) Introduction
  • 2) Observed climate change
  • 3) Projected climate change
  • 4) Summary

3
Average elevation over TP 3500m (above 700hpa)
4
Various land surface
desert
grassland
river
glacier
5
Local meridional vertical circulation
6
Unique circulation system
30N
EQ
30N
EQ
Monsoon cell over TP
Hadley cell
Schematic for comparison
7
2. Observed climate change
8
Annual Ts trends more warming than global mean
0.26?/decade since 1960, in contrast with the
global mean, 0.15
Record high observed in 2006 in 13 sta. of 39
stations within the domain
Duan and Wu (2006)
9
Ts trends decreased diurnal variation
Duan and Wu (2006)
10
Ts in central-eastern Plateau
(85105E, 27.537.5N)
Ts
Diurnal variation
Duan and Wu (2006)
11
Cloudiness lower cloudiness increase at nighttime
12 LT
Lower cloudiness
18 LT
06 LT
00 LT
Total cloudiness
Duan and Wu (2006)
12
annual precipitation climate
Lhasa
Annual rainfall
(mm)
km
13
Annual precip trends more rainfall
Increase by 10
14
Annual Precip evolution in central-eastern
Plateau decadal variation
(85102E, 27.537.5N)
15
Also along with precip decrease in a regional area
trend
Rainfall ano
trend
Rainfall days
trend
Rainfall stre
Precip evolution in a small region where the
three grand rivers originate
16
Ozone
TP
NM
An ozone valley over TP, which is most evident in
summer
Zhou and Zhang (2005)
17
Tropospheric warming, stratospheric cooling
hgt
Zhou and Zhang (2005)
18
Contrast with the north to TP
warming
cooling
198101 195069
Yu et al.(2004)
19
Mechanism atmospheric dynamics?
A
30N
EQ
Monsoon cell over TP
20
Attribution
1) GHG increase
21
Miroc3.2 Simulation with GHG warming trend with
decreased diurnal variation
Pre-industrialized
diurnal
Ts
C20C
diurnal
Ts
Duan and Wu (2006)
22
GFDL CM2.1 Simulation with GHG
Pre-industrialized
diurnal
Ts
C20C
diurnal
Ts
Duan and Wu (2006)
23
2) Ozone depletion?
24
Ozone and stratospheric circulation
Spring
Summer
Zhou and Zhang (2005)
25
3. Future climate change
26
IPCC AR4 Projected climate trend
Increase by 1.5-2 K
Increase by 10-20
A high model consistence
27
Tier-two approach
Tier one
Projected climate in future
External forcing
CSM
Tier two
flexible!
Projected SST in future
CSM
AGCM
External forcing
Projected climate in future
GFDL AM2
GFDL CM2 or CCSM3
28
Obs SST retrospected and projected
29
Projected Precip
Project a wetting trend with the rainfall anomaly
percentage increase by up to 25
30
Projected Ts
Project a warming trend with the magnitude of up
to 1.5K.
Li (2008)
31
Projected Z500 and Z850, V850
A
A
Li (2008)
32
4. Summary
1) TP has exhibited a substantial warming trend
during the recent decades, which is much stronger
than the global mean.
2) TP warming is in accompany with more
precipitation, increased lower cloudiness at
nighttime, depleted ozone, as well as
tropospheric warming and stratospheric cooling,
in contrast with a drying trend and tropospheric
cooling and stratospheric warming downstream.
3) Physically, the warming and wetting trend over
TP is associated with the enhanced southwesterly,
which is partly attributed to GHG increase.
4) Both IPCC models and Tier-2 approach project a
consecutive warming and wetting trend in the
future decades.
33
Discussion
  • The cause for warming GHG radiative effect or
    circulation change?
  • Ozone depletion and enhanced convection cause
    or effect?

34
Thanks !
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