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Enhanced or Weakened Western North Pacific Subtropical High under Global Warming?

He C, Zhou T, Lin A, Wu B, Gu D, Li C, Zheng B - Sci Rep (2015)

Bottom Line: The potential change of the WNPSH under global warming is concerned by Asian people, but whether the WNPSH would be enhanced or weakened remains inconclusive.Weakened meridional temperature gradient on the northern flank of WNPSH and the associated thermal wind account for the weakened WNPSH in the mid troposphere.We recommend the WNPSH be measured by eddy geopotential height (He) instead of traditionally used geopotential height, especially in climate change studies.

View Article: PubMed Central - PubMed

Affiliation: Institute of Tropical and Marine Meteorology (ITMM), China Meteorological Administration (CMA), Guangzhou, China.

ABSTRACT
The Western North Pacific Subtropical High (WNPSH) regulates East Asian climate in summer. Anomalous WNPSH causes floods, droughts and heat waves in China, Japan and Korea. The potential change of the WNPSH under global warming is concerned by Asian people, but whether the WNPSH would be enhanced or weakened remains inconclusive. Based on the multi-model climate change projection from the 5th phase of Coupled Model Intercomparison Project (CMIP5), we show evidences that the WNPSH tends to weaken and retreat eastward in the mid-troposphere in response to global warming, accompanied by an eastward expansion of East Asian rain belt along the northwestern flank of WNPSH. Weakened meridional temperature gradient on the northern flank of WNPSH and the associated thermal wind account for the weakened WNPSH in the mid troposphere. We recommend the WNPSH be measured by eddy geopotential height (He) instead of traditionally used geopotential height, especially in climate change studies.

No MeSH data available.


Related in: MedlinePlus

The latitude-height profile of MME projected changes averaged within 120˚–180˚E.(a) The changes in the zonal wind (shading, unit: m s−1). The black line indicates the climatological interface between trade easterly wind and mid-latitude westerly wind in Historical run. (b) The climatology (contours) and MME projected changes (shading) in temperature (unit: °C). The thick contour shows the 0 °C isotherm, and the contour interval is 10 °C with the negative contours dashed. The MME projected change agreed by over 75% of the individual models are filled with white crosses. The increase of temperature in (b) has exceeded 75% inter-model consensus everywhere, and the white-crosses are omitted. This plot was created by NCAR Command Language36.
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f3: The latitude-height profile of MME projected changes averaged within 120˚–180˚E.(a) The changes in the zonal wind (shading, unit: m s−1). The black line indicates the climatological interface between trade easterly wind and mid-latitude westerly wind in Historical run. (b) The climatology (contours) and MME projected changes (shading) in temperature (unit: °C). The thick contour shows the 0 °C isotherm, and the contour interval is 10 °C with the negative contours dashed. The MME projected change agreed by over 75% of the individual models are filled with white crosses. The increase of temperature in (b) has exceeded 75% inter-model consensus everywhere, and the white-crosses are omitted. This plot was created by NCAR Command Language36.

Mentions: What are the changes in the vertical structure of the WNPSH? As shown in the latitude-height profile of zonal wind changes (Fig. 3a), the westerly wind on the northern flank of WNPSH and the easterly wind on the southern flank of WNPSH both weakens at the mid and lower troposphere. The decelerated westerly wind on the northern flank of WNPSH is evidenced by more than 75% of the models in the mid to upper troposphere, but the inter-model consensus is low at the lower troposphere. The WNPSH is projected to be weakened in the mid troposphere but remains unchanged in the lower troposphere, consistent with the previous study which claimed weak change of WNPSH at 850 hPa18. The projected change of WNPSH shown here doesn’t contradict with previous studies which claimed an intensification of the subtropical high over eastern Pacific27, since the subtropical high over western Pacific differs from that in eastern Pacific28.


Enhanced or Weakened Western North Pacific Subtropical High under Global Warming?

He C, Zhou T, Lin A, Wu B, Gu D, Li C, Zheng B - Sci Rep (2015)

The latitude-height profile of MME projected changes averaged within 120˚–180˚E.(a) The changes in the zonal wind (shading, unit: m s−1). The black line indicates the climatological interface between trade easterly wind and mid-latitude westerly wind in Historical run. (b) The climatology (contours) and MME projected changes (shading) in temperature (unit: °C). The thick contour shows the 0 °C isotherm, and the contour interval is 10 °C with the negative contours dashed. The MME projected change agreed by over 75% of the individual models are filled with white crosses. The increase of temperature in (b) has exceeded 75% inter-model consensus everywhere, and the white-crosses are omitted. This plot was created by NCAR Command Language36.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660429&req=5

f3: The latitude-height profile of MME projected changes averaged within 120˚–180˚E.(a) The changes in the zonal wind (shading, unit: m s−1). The black line indicates the climatological interface between trade easterly wind and mid-latitude westerly wind in Historical run. (b) The climatology (contours) and MME projected changes (shading) in temperature (unit: °C). The thick contour shows the 0 °C isotherm, and the contour interval is 10 °C with the negative contours dashed. The MME projected change agreed by over 75% of the individual models are filled with white crosses. The increase of temperature in (b) has exceeded 75% inter-model consensus everywhere, and the white-crosses are omitted. This plot was created by NCAR Command Language36.
Mentions: What are the changes in the vertical structure of the WNPSH? As shown in the latitude-height profile of zonal wind changes (Fig. 3a), the westerly wind on the northern flank of WNPSH and the easterly wind on the southern flank of WNPSH both weakens at the mid and lower troposphere. The decelerated westerly wind on the northern flank of WNPSH is evidenced by more than 75% of the models in the mid to upper troposphere, but the inter-model consensus is low at the lower troposphere. The WNPSH is projected to be weakened in the mid troposphere but remains unchanged in the lower troposphere, consistent with the previous study which claimed weak change of WNPSH at 850 hPa18. The projected change of WNPSH shown here doesn’t contradict with previous studies which claimed an intensification of the subtropical high over eastern Pacific27, since the subtropical high over western Pacific differs from that in eastern Pacific28.

Bottom Line: The potential change of the WNPSH under global warming is concerned by Asian people, but whether the WNPSH would be enhanced or weakened remains inconclusive.Weakened meridional temperature gradient on the northern flank of WNPSH and the associated thermal wind account for the weakened WNPSH in the mid troposphere.We recommend the WNPSH be measured by eddy geopotential height (He) instead of traditionally used geopotential height, especially in climate change studies.

View Article: PubMed Central - PubMed

Affiliation: Institute of Tropical and Marine Meteorology (ITMM), China Meteorological Administration (CMA), Guangzhou, China.

ABSTRACT
The Western North Pacific Subtropical High (WNPSH) regulates East Asian climate in summer. Anomalous WNPSH causes floods, droughts and heat waves in China, Japan and Korea. The potential change of the WNPSH under global warming is concerned by Asian people, but whether the WNPSH would be enhanced or weakened remains inconclusive. Based on the multi-model climate change projection from the 5th phase of Coupled Model Intercomparison Project (CMIP5), we show evidences that the WNPSH tends to weaken and retreat eastward in the mid-troposphere in response to global warming, accompanied by an eastward expansion of East Asian rain belt along the northwestern flank of WNPSH. Weakened meridional temperature gradient on the northern flank of WNPSH and the associated thermal wind account for the weakened WNPSH in the mid troposphere. We recommend the WNPSH be measured by eddy geopotential height (He) instead of traditionally used geopotential height, especially in climate change studies.

No MeSH data available.


Related in: MedlinePlus