Layers of the Atmosphere. Layers Troposphere Stratosphere Mesosphere Thermosphere Exosphere.
A Possible Impact Way of the Stratosphere on Troposphere
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Transcript of A Possible Impact Way of the Stratosphere on Troposphere
A Possible Impact Way of the Stratosphere on Troposphere
LI Chongyin, PAN JingLASG, Institute of Atmospheric Physics
ASM-STELhasa, July 21-23, 2010
I. IntroductionInteraction between the stratosphere andtroposphere (a hypothesis)
Mid-Lati.Low-Lati. High-lati.
Tropopausebreak
Planetary waveStrong convection
Stratosphere impact on the troposphere at high latitude
-----The Cosmic Rays ---- Clouds
Marsh and Svensmark (2000)
-----The circulation at high latitudes
How about the impact of polar vortex on the AO ?
As an example, in this study we will discuss :
AO in troposphere
Stratospherepolar vortex
Mei-yu anomalies
The Mei-yu has a great social and economic
importance in China, its anomaly often causes t
he flood or drought over the Yangtze River Val
ley in summer.
It is an important problem to study Mei-yu
and its variability in China
II. The Used Data
The 121yr Mei-yu dataset (1885 – 2005) is from
National Climate Center of CMA, which describes t
he precipitation, duration, start date and end date o
f Mei-yu season; It is constructed by averaging data
at 5 stations: Shanghai, Nanjing, Wuhu, Jiujiang an
d Wuhan.
The atmospheric circulation data (1948–2006) a
re from the NCEP (reanalysis).
III. The AO and Mei-yu
1. The correlation between the Mei-yu
precipitation and AO ;
2. The AO in March and Atmospheric circulation in summer
AO (Arctic Oscillation) Thompson and Wallace ( 2000 ) found that the SLP field in the high l
atitude has variation out-of-phase to that in the middle latitude and this patt
ern is symmetric longitudinally. It was named the Arctic Oscillation, or the
Northern Annular Mode (NAM).
Is there a relationship between the Mei-yu variation and the AO?
1960 1965 1970 1975 1980 1985 1990 1995 2000
-2
0
2
Normalized AO index in March (dashed) and mei-yu precipitation (solid) from 1958 to 2002
Correlation coefficients between monthly AO indices and mei-yu precipitation from 1958 to 2002.
(* indicates the 95% significance level)
Months Correlation coefficientsJan. -0.01
Feb. 0.07
Mar. -0.31*
Apr. -0.04May -0.16Jun. -0.05
Jul. 0.03
Agu. -0.01
There is remarkable correlation between the Mei-yu precipitation in summer and AO index in last March
Correlation between the Mei-yu and SLP/geopotential height i
n March
SLP
SLP 500hPa
500hPa
The Mei-yu is closely related to the AO mode in March
Correlation between the AO index and SLP/geopotential heig
ht in March
Correlation between the Mei-yu and zonal mean geopotential height in March( 1958- 2002)
AO mode
95 % (significance)99 %
Summertime 200-850hPa thickness regressed on March AO index. (Units: gpm, dark and light shadings indi
cate 99% and 95% significance levels)
Why the AO in March can affect on summer mei-yu?
Latitudinal-height section of the averaged wind field between (110º - 150ºE ) in summer regressed on March A
O index. (Vertical speed is multified by 10 )
AO anomaly in march could cause summer circulation anomalies in East Asia, which is favorable (unfavorable) to the Mei-yu rainfall.
IV. Stratospheric Polar Vortexin Feb. and the AO in Mar.
1. Their relationship;
2. The downward propagating of anomalies in the stratosphere
Distribution of correlation coefficients between March AO index and latitudinal averaged height in February.
(Dark and light shadings is 99% and 95% significance levels)
Correlation coefficients between AO index in March and 30hPa height field in the previous September (a), October (b), November (c),
December (d), January (e) and February (f).
Sep. Nov.
Feb.Dec.
The SLP and 500hPa height in March regressed on 1st PC and 3rd PC of 30hPa height in February,
shadings is 99% and 95% significance levels
-+
NAM-like
-
-
-
-
E-P flux in February regressed on 1st (a) and 3rd (b) PC of 30hPa geopotential height in February.
(Dark and light shadings indicate 95% and 90% significance levels)
AO index in March has evident correlation with the stratospheric polar vortex in February. There is downward wave activityfrom the stratosphere and will affect
the troposphere circulation in the high latitude (AO).
V. Conclusions
2. The stratospheric atmosphere circulation in February is closely related to the AO in March. It may affect the AO through the downward propagating of wave activity anomalies.
1. It is shown that the mei-yu precipitation may be influenced by the stratospheric polar vortex anomaly through the Arctic Oscillation (AO) in troposphere.
3. The anomalous AO in March may in turn exert an impact on summertime circulation in East Asia, which is closely related to thermal condition of the tropospheric atmosphere in summer over East Asia. The changed thermal condition and the circulation over East Asia can then lead to anomalous convergence (divergence) over the Yangtze River Valley, and anomaly of Mei-yu precipitation.
Schematic diagram
Polar vortex anomaly in the Stratosphere in Feb.
AO anomalyin March
Summer circulation Anomaly over East Asia
Mei-yu anomaly
in summer
?downward propagating
of wave activity