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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

Projected changes for the WNPSH under RCP8.5 (2050–2099 average) relative to Historical run (1950–1999 average).(a) MME projected change in H (shading, unit: m) and wind (vectors, unit: m·s−1). The changes in wind exceeding 75% consensus among the 31 models are filled by blue dots. The solid line is the He = 0 m contour and the dashed line is the Se = 0 m2 s−1 contour. The blue and red lines stand for Historical and RCP8.5 runs, respectively. (b) The WNP (10˚–30˚N, 120˚E-180˚, i.e. the box in Fig. 2a) averaged changes in He (unit: m, left y-axis) and Se (unit: m2 s−1, right y-axis). The thick blue bars indicate the MME, and the thin black error bars show the range of the 25th and 75th percentiles of individual models. This plot was created by NCAR Command Language36.
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f2: Projected changes for the WNPSH under RCP8.5 (2050–2099 average) relative to Historical run (1950–1999 average).(a) MME projected change in H (shading, unit: m) and wind (vectors, unit: m·s−1). The changes in wind exceeding 75% consensus among the 31 models are filled by blue dots. The solid line is the He = 0 m contour and the dashed line is the Se = 0 m2 s−1 contour. The blue and red lines stand for Historical and RCP8.5 runs, respectively. (b) The WNP (10˚–30˚N, 120˚E-180˚, i.e. the box in Fig. 2a) averaged changes in He (unit: m, left y-axis) and Se (unit: m2 s−1, right y-axis). The thick blue bars indicate the MME, and the thin black error bars show the range of the 25th and 75th percentiles of individual models. This plot was created by NCAR Command Language36.

Mentions: Compared with Historical run, the He = 0 m and the Se = 0 m2 s−1 contours both contract in RCP8.5 run, and their western edge retreats eastward (contours in Fig. 2a). The contraction of the He = 0 m contour indicates that the increase of H over the WNP is smaller than the zonal mean (See supplementary Fig. S1). Indeed, decreases of He and Se over WNP (10˚–30˚N, 120˚E-180˚ averaged) are seen in more than 75% of the individual models. The MME projected decrease of He is 3.7 m, and the MME projected decrease of Se is 3.0 × 106 m2 s−1 (Fig. 2b). Following the contraction and eastward retreat of the He = 0 m and Se = 0 m2 s−1 contours, the rain belt around Japan expands eastward (Fig. 1b,c). The changes in He, Se and rainfall both suggest a weakened and eastward retreated WNPSH at 500 hPa as climate warms.


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)

Projected changes for the WNPSH under RCP8.5 (2050–2099 average) relative to Historical run (1950–1999 average).(a) MME projected change in H (shading, unit: m) and wind (vectors, unit: m·s−1). The changes in wind exceeding 75% consensus among the 31 models are filled by blue dots. The solid line is the He = 0 m contour and the dashed line is the Se = 0 m2 s−1 contour. The blue and red lines stand for Historical and RCP8.5 runs, respectively. (b) The WNP (10˚–30˚N, 120˚E-180˚, i.e. the box in Fig. 2a) averaged changes in He (unit: m, left y-axis) and Se (unit: m2 s−1, right y-axis). The thick blue bars indicate the MME, and the thin black error bars show the range of the 25th and 75th percentiles of individual models. 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

f2: Projected changes for the WNPSH under RCP8.5 (2050–2099 average) relative to Historical run (1950–1999 average).(a) MME projected change in H (shading, unit: m) and wind (vectors, unit: m·s−1). The changes in wind exceeding 75% consensus among the 31 models are filled by blue dots. The solid line is the He = 0 m contour and the dashed line is the Se = 0 m2 s−1 contour. The blue and red lines stand for Historical and RCP8.5 runs, respectively. (b) The WNP (10˚–30˚N, 120˚E-180˚, i.e. the box in Fig. 2a) averaged changes in He (unit: m, left y-axis) and Se (unit: m2 s−1, right y-axis). The thick blue bars indicate the MME, and the thin black error bars show the range of the 25th and 75th percentiles of individual models. This plot was created by NCAR Command Language36.
Mentions: Compared with Historical run, the He = 0 m and the Se = 0 m2 s−1 contours both contract in RCP8.5 run, and their western edge retreats eastward (contours in Fig. 2a). The contraction of the He = 0 m contour indicates that the increase of H over the WNP is smaller than the zonal mean (See supplementary Fig. S1). Indeed, decreases of He and Se over WNP (10˚–30˚N, 120˚E-180˚ averaged) are seen in more than 75% of the individual models. The MME projected decrease of He is 3.7 m, and the MME projected decrease of Se is 3.0 × 106 m2 s−1 (Fig. 2b). Following the contraction and eastward retreat of the He = 0 m and Se = 0 m2 s−1 contours, the rain belt around Japan expands eastward (Fig. 1b,c). The changes in He, Se and rainfall both suggest a weakened and eastward retreated WNPSH at 500 hPa as climate warms.

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