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Recent Reversal of the Upper-Tropospheric Temperature Trend and its Role in Intensifying the East Asian Summer Monsoon.

Zhao S, Li J, Yu R, Chen H - Sci Rep (2015)

Bottom Line: Together with the temperature rising, the geo-potential height rises above the warming center and drops below, which connects closely to a correspondingly significant decadal shift of the general circulation over East Asia.As the cooling center in the 1970 s moves southward, the dry belt moves southward as well.A wet belt dominates the Huaihe River Valley after the temperature trend reversal at 2005 while southern China experiences a dry condition.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, No. 46 Zhong-Guan-Cun South Street, Beijing, 100081, China.

ABSTRACT
At the beginning of the 21st century, the July and August (JA) mean upper-tropospheric temperature over East Asia shows a significant increasing trend, contrary to the decreasing trend in the late 1970 s. The largest warming center is over northern China (between 30°N-45°N and 85°E-120°E) around 300 hPa. Together with the temperature rising, the geo-potential height rises above the warming center and drops below, which connects closely to a correspondingly significant decadal shift of the general circulation over East Asia. In the upper-level of the troposphere, an anomalous anti-cyclone dominates, and the 200-hPa westerly jet strengthens due to the increasing pole-ward geo-potential height gradient. In the lower-troposphere, the anomalous southerly wind increases around Yangtze River Valley and the East Asian summer monsoon intensifies. The integrated circulation changes seriously impact summer precipitation over East Asia. The so-called "southern flood and northern drought" (SFND) pattern since the 1970 s over eastern China has changed. As the cooling center in the 1970 s moves southward, the dry belt moves southward as well. A wet belt dominates the Huaihe River Valley after the temperature trend reversal at 2005 while southern China experiences a dry condition.

No MeSH data available.


Related in: MedlinePlus

Precipitation change associated with the upper-tropospheric temperature change.(a) Inter–decadal change (2005–2013 minus 1994–2004) of the JA mean precipitation (mm/d) over eastern China. Red (blue) dots are the stations significant decrease (increase) at the 90% confidence level (using Student’s t-test). (b) 11 year smoothed precipitation anomalies (mm/d) averaged between 105°E–120°E. The map in the figure were created by Z.S. using The NCAR Command Language34 (http://www.ncl.ucar.edu/).
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f3: Precipitation change associated with the upper-tropospheric temperature change.(a) Inter–decadal change (2005–2013 minus 1994–2004) of the JA mean precipitation (mm/d) over eastern China. Red (blue) dots are the stations significant decrease (increase) at the 90% confidence level (using Student’s t-test). (b) 11 year smoothed precipitation anomalies (mm/d) averaged between 105°E–120°E. The map in the figure were created by Z.S. using The NCAR Command Language34 (http://www.ncl.ucar.edu/).

Mentions: Corresponding to the monsoon circulation change, the precipitation over eastern China also changes. As mentioned before, the upper-level westerly jet strengthens in the north of the warming center and generates strong ascending flows over northern China. The East Asian summer monsoon strengthens and brings more water vapor across the Yangtze River. These circulation changes lead more rainfall to Huaihe River Valley (30°N–35°N) and less in southern China with a clear boundary along Yangtze River (30°N) (Fig. 3a). The region with significant increase of precipitation is centered along Huaihe River Valley (30°N–35°N) and the stations with significant decrease are widely distributed in the regions south of Yangtze River (20°N–31°N).


Recent Reversal of the Upper-Tropospheric Temperature Trend and its Role in Intensifying the East Asian Summer Monsoon.

Zhao S, Li J, Yu R, Chen H - Sci Rep (2015)

Precipitation change associated with the upper-tropospheric temperature change.(a) Inter–decadal change (2005–2013 minus 1994–2004) of the JA mean precipitation (mm/d) over eastern China. Red (blue) dots are the stations significant decrease (increase) at the 90% confidence level (using Student’s t-test). (b) 11 year smoothed precipitation anomalies (mm/d) averaged between 105°E–120°E. The map in the figure were created by Z.S. using The NCAR Command Language34 (http://www.ncl.ucar.edu/).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4488833&req=5

f3: Precipitation change associated with the upper-tropospheric temperature change.(a) Inter–decadal change (2005–2013 minus 1994–2004) of the JA mean precipitation (mm/d) over eastern China. Red (blue) dots are the stations significant decrease (increase) at the 90% confidence level (using Student’s t-test). (b) 11 year smoothed precipitation anomalies (mm/d) averaged between 105°E–120°E. The map in the figure were created by Z.S. using The NCAR Command Language34 (http://www.ncl.ucar.edu/).
Mentions: Corresponding to the monsoon circulation change, the precipitation over eastern China also changes. As mentioned before, the upper-level westerly jet strengthens in the north of the warming center and generates strong ascending flows over northern China. The East Asian summer monsoon strengthens and brings more water vapor across the Yangtze River. These circulation changes lead more rainfall to Huaihe River Valley (30°N–35°N) and less in southern China with a clear boundary along Yangtze River (30°N) (Fig. 3a). The region with significant increase of precipitation is centered along Huaihe River Valley (30°N–35°N) and the stations with significant decrease are widely distributed in the regions south of Yangtze River (20°N–31°N).

Bottom Line: Together with the temperature rising, the geo-potential height rises above the warming center and drops below, which connects closely to a correspondingly significant decadal shift of the general circulation over East Asia.As the cooling center in the 1970 s moves southward, the dry belt moves southward as well.A wet belt dominates the Huaihe River Valley after the temperature trend reversal at 2005 while southern China experiences a dry condition.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, No. 46 Zhong-Guan-Cun South Street, Beijing, 100081, China.

ABSTRACT
At the beginning of the 21st century, the July and August (JA) mean upper-tropospheric temperature over East Asia shows a significant increasing trend, contrary to the decreasing trend in the late 1970 s. The largest warming center is over northern China (between 30°N-45°N and 85°E-120°E) around 300 hPa. Together with the temperature rising, the geo-potential height rises above the warming center and drops below, which connects closely to a correspondingly significant decadal shift of the general circulation over East Asia. In the upper-level of the troposphere, an anomalous anti-cyclone dominates, and the 200-hPa westerly jet strengthens due to the increasing pole-ward geo-potential height gradient. In the lower-troposphere, the anomalous southerly wind increases around Yangtze River Valley and the East Asian summer monsoon intensifies. The integrated circulation changes seriously impact summer precipitation over East Asia. The so-called "southern flood and northern drought" (SFND) pattern since the 1970 s over eastern China has changed. As the cooling center in the 1970 s moves southward, the dry belt moves southward as well. A wet belt dominates the Huaihe River Valley after the temperature trend reversal at 2005 while southern China experiences a dry condition.

No MeSH data available.


Related in: MedlinePlus