Long-term variation of heat
sources over the Tibetan Plateau
and its impact on the Asian
summer monsoon
Ding Yihui , Si Dong,Sun Ying, Wang Zunya,Liu Yunyun
China meteorological Administration, National Climate Center
April 8,2013
Outline
1.Long -term variations of heat sources over
the Tibetan Plateau (TP)
2. Impact of Long-tem variation of heat source
over TP on the Asian summer monsoon
3. Future change in the Asian summer
monsoon and its association with TP heating
variation
Main driving force of the Asian
summer monsoon
It is widely accepted that the development of
the Asian summer monsoon (ASM) is
induced by large-scale thermal gradients
between the Asiatic landmass and
neighboring oceans. Many researchers have
indicated that the Tibetan Plateau is an
important player in the heating processes as
an elevated heat source in the middle
troposphere.
The Asian summer monsoon system
The Asian summer monsoon is composed by South or
Southeast Asian monsoon, Western North Pacific monsoon,
and East Asian monsoon . All these systems experience clear
alternation of wind directions and wet/dry seasons.
Based on studies over many years, it has been found that
many differences exist between the monsoon circulation over
India and that over East Asia. This suggests that the
structure and main components of the monsoon system over
East Asia is likely to be independent of the Indian monsoon
system, even though there are some significant interactions.
Long -term variations of heat sources over the Tibetan
Plateau (TP)
Computational formula：
Integrating from surface to 100hPa
2
Estimates of surface sensible heat
H=ρ·cp·CH·U·(Ts-Ta)
CH =0.0012+0.01/U (Chen and Wong 1984)
Long-tem variations of heat source over TP
from surface to 100 hPa
垂直积分的（地面至100 hPa）高原地区（27.5°～42.5°N，75°～105°E ）异常热源
（Q1）的时间序列：（a）夏季；（b）春季。实线为9 年滑动平均，单位：W m-2。、
（引自Ding et al., 2009）
Land –sea thermal contrast (Thermal difference index QLS)
亚洲季风区及其相邻海岸区陆地（547 个格点，见右上角小图中的计算区）与海
洋（668 个格点）（20°S～45°N，30°～140°E）热力差异指数（QLS）的时
间序列。实线为9 年滑动平均。
（引自Ding et al., 2009）
Temperature
variation of
QLS
(1979-2011)
Time series of the difference between the normalized vertically integrated (from surface to 250 hPa)
apparent heat source Q1 (W m-2) averaged over the Tibetan Plateau (70°–100°E, 30°–43°N)
and the tropical central and eastern Pacific (180°–120°W, 10°S–10°N) for the (a) spring and (b)
summer. The solid lines denote 9-year running mean curves.
Inter-decadal weakening of meridional temperature gradient for the layer of 500-100hPa
In South Asian (top) and Zonal temperature gradient in East Asia (bottom) for JJA
（a）南亚夏季风区（0°～20°N，40°～105°E）500～100 hPa层平均经向温度梯度∂ΔH / ∂y 变化，由
异常平均经向厚度梯度代表。（b）东亚季风区（沿30°N，110°～140°E）平均纬向温度梯度，由异常纬向
厚度梯度−∂ΔH / ∂y 代表。单位：10-2 gpm km−1。
（引自Ding et al., 2009）
Temporal
variation
of heat
source TP
and QLS
for 19792011
（a）1979～2011 年高原地区（30°～43°N，70°～100°E ）春季垂直积分（地表至250 hPa）的异常Q1
时间序列（单位：W m-2），实线为9年滑动平均；（b）同（a），但为夏季；（c）春季高原地区（同上）
和热带中东太平洋（10°S～10°N，180°～120°W ）垂直积分热源（Q1，单位：Wm–2）差值的时间序列；
（d）同（c），但为夏季。实线为9 年滑动平均。
（引自 Si and Ding., 2012）
Temporal
variation of
sensible heat
flux over TP
for 1979-2011
Seasonal mean sensible heat fluxes (W m-2) over the Tibetan Plateau
averaged for the 72 station for the (a) winter, (b) spring, and (c) summer.
The dashed curve indicates the third-order polynomial fit. The horizontal
solid lines indicate averaged values for the period of 1979-2011.
Longer temporal variation of heat sources over TP for 1948-2011
50
40
W/m2
spring
30
20
10
0
1948 1954 1960 1966 1972 1978 1984 1990 1996 2002 2008
Year
80
70
W/m2
summer
60
50
40
30
20
1948 1954 1960 1966 1972 1978 1984 1990 1996 2002 2008
Year
（司东博士提供，2013）
28
24
winter
20
16
12
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
55
53
51
spring
49
47
45
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
Longer
variation
of the
surface
sensible
heat flux
over TP for
1960-2011
58
56
54
summer
52
50
48
46
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
（司东博士提供，2013）
Decadal
increase in
upward
longwave
radiation over
TP for 20002007
Changes (2000-2007 mean minus 1984-1999 mean) in surface
longwave radiation ratio (%) (surface longwave upward flux / surface
longwave downward flux ) in (a) winter, (b) spring, and (c) summer.
Temperature
variations
derived from
radiosondes at
various levels
in TP region
(a) Distribution of the 15 radiosonde stations over the Tibetan Plateau.
(b) Spring and (c) summer temperature (°C) over the Tibetan Plateau averaged for the
15 radiosonde stations from 500 hPa to 100 hPa. The horizontal solid lines indicate averaged
values for the period of 1999-2011. The Dashed curves indicate the third-order polynomial fits.
1960-2004
Long-term
variations
of
preceding
winter and
spring
snow-depth
over TP
1979-2011
1960～2004 年青藏高原50 个站（见左上小图）平均积雪深度指数（SDI）时间序列：（a）
冬季（12～2 月），（b）春季（3～4 月），（c）春季EOF 第一模态时间系数，虚线为9
年滑动平均，单位：cm（引自Ding et al. 2009）；（d）1979～2011 年高原72 站冬季积
雪深度，单位：cm d–1
（引自Si and Ding. 2012）
2. Impact of Long-tem variation of
heat source over TP on the Asian
summer monsoon
summer
winter
Long-term
variations
of the
monsoon
index for
1951-2011
(BCC,2011)
Long-term
variations of
the monsoon
index for
1951-2012
Top:
Bottom:
东亚夏季风（上）与南亚夏季风（下）持续年代际偏弱
（周兵等，2013）
EA index
SA index
Pattern of annual precipitation for 1950-2002
年降水标准化距平序列与自然数列1，2，3，…， 的相关系数。相关系数正负表示增或减
Monsoon precipitation
Arid-and semi-arid
precipitation
（中国气象局国家气候中心）
西部、华南降水呈增加趋势；华北、东北大部降水呈减少趋势
Patterns of anomalous
precipitation for 19511978(top),19791992(middle) and 19932004 (bottom) for JJA
Latitude-time
cross-sections of
anomalous
precipitation (top)
and 850hPa Vcomponent
(bottom) for JJA
Decadal change in
correlation relationship
between TP winter snow
and summer precipitation
from 1960-2004 to 20002011
Schematic diagram of
inter-decadal
weakening of the
Asian summer
monsoon
亚洲夏季风减弱可能原因的概略图。异常强、弱的夏季风条件由（a）、（b）驱动。阴
影区为多雪、高SSTA、强大气加热和多雨。粗箭头为夏季风气流。
（引自Ding et al., 2009）
3. Future change in the Asian summer
monsoon and its association with TP
heating variation
Latitude-time cross-section of East Asian summer precipitation for 2010-2099
2010-2099东亚夏季风的纬度时间剖面图
2010-2019
2030-2039
JJA
precipitation
2080-2099
Percentage changes (%) of JJA precipitation (relative to 1980–1999 average) for
2010–2019 (a), 2030–2039 (b) and 2080–2099 (c).
Future change of the East Asian summer index for next 100 years
( based on the definition of monsoon index by Lu and Chan, with estimate of the V-component of wind).
未来百年东亚夏季风指数的长期变化
Projection of future variations of Asian
summer monsoon based on IPCC AR4
14 coupled models
Changes in monsoon indices for South Asia in the period of 2010-1099
(Webster and Yang：实线， Wang and Fang：虚线)
South
Asia
2010-2099南亚夏季风指数演变
IPCC 9-model mean June-July-August (JJA) sea level pressure (Pa, shaded
area) and 850 hPa winds (m/s, arrows) for 1980–1999 (blank areas in wind
fields represents geographical heights greater than 1500 m).
Simulated Sea level pressure for 1980–1999
Projected trends of mean temperature profiles of TP, TIO, and NWP for
2000-2009
Trends (K/decade) for 2000–2099 temperatures averaged over TP (black), TIO (red), and NWP (blue) from 850 hPa to
100 hPa. The orange line indicates the trend (K/decade) in near-surface temperature over the TP
Latitude –height cross -section of temperature change along TP-TIO and TPNWP for 2080-2099
(a)IPCC 9-model mean latitude-height cross-section of JJA temperature changes (K, relative to 1980–1999 average) along the
longitude belt (i.e.60°–100°E average) over the TP and TIO for 2080–2099. (b) Same as (a), but for the longitude-height
cross-section along the latitude belt (i.e., 20°–40°N average) over the TP and NWP.
Continued weakening of meridional temperature gradient
between TP and TIO in the future (2080-2099)
IPCC AR4 9 个耦合模式平均的2080～2099 年对TP 与TIO 所在纬度带的经向热力差
异变化高度—经度剖面图。 （即20°N～40°N 减10°S～10°N平均的变化，相对于
1980～1999 年平均）。实（虚）线为正（负）距平。实（虚）线代表（TP–TIO）经
向梯度加强（减弱）。可见对流层中上部TP 以及其以南地区的经向温度梯度减弱
（单位：K）
Projected change in precipitation amount over the Asian-Australian monsoon
region in June-August due to human-induced climate change using the Coupled
Model Intercomparison Project-3 models.
The left panels show the 2001-2100 trend in mm/day (21-model average), and the right panels show the number of models (of 21)
that have an increasing trend. The figure is adapted from Christensen et al. (Regional Climate Projections. In: Climate Change
2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental
Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)].
Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA).
谢谢！