Variability of North Pacific Sea Ice and East Asia–North Pacific Winter Climate

2007 ◽  
Vol 20 (10) ◽  
pp. 1991-2001 ◽  
Author(s):  
Jiping Liu ◽  
Zhanhai Zhang ◽  
Radley M. Horton ◽  
Chunyi Wang ◽  
Xiaobo Ren
Keyword(s):  
Sea Ice ◽  
East Asia ◽  
North Pacific ◽  
East Asian ◽  
Jet Stream ◽  
Winter Climate ◽  
The North ◽  
Local Warming ◽  
Northern Pacific ◽  
The North Pacific

Abstract Sea ice variability in the North Pacific and its associations with the east Asia–North Pacific winter climate were investigated using observational data. Two dominant modes of sea ice variability in the North Pacific were identified. The first mode features a dipole pattern between the Sea of Okhotsk and the Bering Sea. The second mode is characterized by more uniform ice changes throughout the North Pacific. Using the principal components of the two dominant modes as the indices (PC1 and PC2), analyses show that the positive phases of PC1 feature a local warming (cooling) in the Sea of Okhotsk (the Bering Sea), which is associated with the formation of the anomalous anticyclone extending from the northern Pacific to Siberia, accompanied by a weakening of the east Asian jet stream and trough. The associated anomalous southeasterlies/easterlies reduce the climatological northwesterlies/westerlies, leading to warm and wet conditions in northeast China and central Siberia. The positive phases of PC2 are characterized by a strong local warming in the northern Pacific that coincides with the anomalous cyclone occupying the entire North Pacific, accompanied by a strengthening of the east Asia jet stream and trough. The associated anomalous northerlies intensify the east Asian winter monsoon (EAWM), leading to cold and dry conditions in the east coast of Asia. The intensified EAWM also strengthens the local Hadley cell, which in turn strengthens the east Asian jet stream and leads to a precipitation deficit over subtropical east Asia. The linkages between PC1 and PC2 and large-scale modes of climate variability were also discussed. It is found that PC1 is a better indicator than the Arctic Oscillation of the recent Siberian warming, whereas PC2 may be a valuable predictor of EAWM.

scholarly journals Impact of Stratospheric Sudden Warming on East Asian Winter Monsoons

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Quanliang Chen ◽  
Luyang Xu ◽  
Hongke Cai
Keyword(s):  
East Asia ◽  
North Pacific ◽  
East Asian ◽  
Planetary Waves ◽  
The Arctic ◽  
Reanalysis Dataset ◽  
Stratospheric Sudden Warming ◽  
The North ◽  
Tropospheric Circulation ◽  
The North Pacific

Fifty-two Stratospheric sudden warming (SSW) events that occurred from 1957 to 2002 were analyzed based on the 40-year European Centre for Medium-Range Weather Forecasts Reanalysis dataset. Those that could descent to the troposphere were composited to investigate their impacts on the East Asian winter monsoon (EAWM). It reveals that when the SSW occurs, the Arctic Oscillation (AO) and the North Pacific Oscillation (NPO) are both in the negative phase and that the tropospheric circulation is quite wave-like. The Siberian high and the Aleutian low are both strengthened, leading to an increased gradient between the Asian continent and the North Pacific. Hence, a strong EAWM is observed with widespread cooling over inland and coastal East Asia. After the peak of the SSW, in contrast, the tropospheric circulation is quite zonally symmetric with negative phases of AO and NPO. The mid-tropospheric East Asian trough deepens and shifts eastward. This configuration facilitates warming over the East Asian inland and cooling over the coastal East Asia centered over Japan. The activities of planetary waves during the lifecycle of the SSW were analyzed. The anomalous propagation and the attendant altered amplitude of the planetary waves can well explain the observed circulation and the EAWM.

Impact of Sea Ice Reduction in the Barents and Kara Seas on the Variation of the East Asian Trough in Late Winter

2021 ◽  
Vol 34 (3) ◽  
pp. 1081-1097
Author(s):  
Mian Xu ◽  
Wenshou Tian ◽  
Jiankai Zhang ◽  
Tao Wang ◽  
Kai Qie
Keyword(s):  
Sea Ice ◽  
Rossby Wave ◽  
North Pacific ◽  
East Asian ◽  
Late Winter ◽  
East Asian Trough ◽  
The North ◽  
Wave Ray ◽  
The North Pacific ◽  
Sea Ice Reduction

AbstractUsing the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim) dataset and the Specified Chemistry Whole Atmosphere Community Climate Model (WACCM-SC), the impacts of sea ice reduction in the Barents–Kara Seas (BKS) on the East Asian trough (EAT) in late winter are investigated. Results from both reanalysis data and simulations show that the BKS sea ice reduction leads to a deepened EAT in late winter, especially in February, while the EAT axis tilt is not sensitive to the BKS sea ice reduction. Further analysis shows that the BKS sea ice reduction influences the EAT through the tropospheric and stratospheric pathways. For the tropospheric pathway, the results from a linearized barotropic model and Rossby wave ray tracing model reveal that long Rossby wave trains stimulated by the BKS sea ice loss propagate downstream to the North Pacific, strengthening the EAT. For the stratospheric pathway, the upward planetary waves enhanced by the BKS sea ice reduction shift the subpolar westerlies near the tropopause southward. With the critical lines displaced equatorward, the poleward transient eddies break at lower latitudes, shifting the eddy momentum deposit throughout the troposphere equatorward. Tropospheric westerlies maintained by eddy momentum deposit are also shifted southward, inducing the cyclonic anomalies over the North Pacific and deepening the EAT in late winter. Nudging experiments show that the tropospheric pathway only contributes to around 29.7% of the deepening of the EAT in February induced by the BKS sea ice loss, while the remaining 70.3% is caused by stratosphere–troposphere coupling.

Interannual Variations of East Asian Trough Axis at 500 hPa and its Association with the East Asian Winter Monsoon Pathway

2009 ◽  
Vol 22 (3) ◽  
pp. 600-614 ◽  
Author(s):  
Lin Wang ◽  
Wen Chen ◽  
Wen Zhou ◽  
Ronghui Huang
Keyword(s):  
East Asia ◽  
North Pacific ◽  
East Asian Winter Monsoon ◽  
Regional Climate ◽  
East Asian ◽  
Winter Monsoon ◽  
Interannual Variations ◽  
Asian Winter Monsoon ◽  
The North ◽  
The North Pacific

Abstract Interannual variations of the East Asian trough (EAT) axis at 500 hPa are studied with the European Centre for Medium-Range Weather Forecasts 40-yr reanalysis data. The associated circulation pattern and pathway of the East Asian winter monsoon (EAWM) with the EAT axis tilt are specially investigated with a trough axis index, which is closely related to the midlatitude baroclinic process and mainly represents the intensity of the eddy-driven jet over the East Asia–North Pacific sector. When the tilt of EAT is smaller than normal, the EAWM prefers to take the southern pathway and less cold air moves to the central North Pacific. However, the EAWM prefers the eastern pathway and brings more cold air to the North Pacific when the tilt of EAT is larger than normal. These differences induce pronounced changes in both the precipitation and the surface air temperature over East and Southeast Asia. Furthermore, the tilt status of the EAT has a significant modulation effect on the regional climate anomalies related to the intensity of the EAWM. The findings suggest an increase in the temperature anomaly associated with the EAWM intensity and a clear northward–southward shift in its pattern in anomalous tilt phase of the EAT. In addition, the modulation tends to be confined mainly to East Asia and expanded to a larger area during the weak and the strong EAWM winters, respectively. The possible reasons for interannual variations of the EAT tilt are discussed, and it is speculated that the midlatitude air–sea interaction in the North Pacific plays a dominant role. This study on the EAT tilt may enrich knowledge of the East Asian winter monsoon beyond the conventional intensity index and may be helpful to improve regional climate prediction in East Asia.

Responses of the East Asian jet stream to the North Pacific subtropical front in spring

2017 ◽  
Vol 34 (2) ◽  
pp. 144-156 ◽  
Author(s):  
Leying Zhang ◽  
Haiming Xu ◽  
Ning Shi ◽  
Jiechun Deng
Keyword(s):  
North Pacific ◽  
East Asian ◽  
Jet Stream ◽  
Subtropical Front ◽  
The North ◽  
East Asian Jet Stream ◽  
The North Pacific

scholarly journals Source-receptor relationships between East Asian sulfur dioxide emissions and Northern Hemisphere sulfate concentrations

2008 ◽  
Vol 8 (2) ◽  
pp. 5537-5561 ◽  
Author(s):  
J. Liu ◽  
D. L. Mauzerall ◽  
L. W. Horowitz
Keyword(s):  
Northern Hemisphere ◽  
North Pacific ◽  
East Asian ◽  
Source Region ◽  
The United States ◽  
So2 Emissions ◽  
Aerosol Model ◽  
The North ◽  
The North Pacific ◽  
Sulfur Emissions

Abstract. We analyze the effect of varying East Asian (EA) sulfur emissions on sulfate concentrations in the Northern Hemisphere, using a global coupled oxidant-aerosol model (MOZART-2). We conduct a base and five sensitivity simulations, in which sulfur emissions from each continent are tagged, to establish the source-receptor (S-R) relationship between EA sulfur emissions and sulfate concentrations over source and downwind regions. We find that from west to east across the North Pacific, EA sulfate contributes approximately 80%–20% of sulfate at the surface, but at least 50% at 500 hPa. In addition, EA SO2 emissions account for approximately 30%–50% and 10%–20% of North American background sulfate over the western and eastern US, respectively. The contribution of EA sulfate to the western US at the surface is highest in MAM and JJA, but is lowest in DJF. Reducing EA SO2 emissions will significantly decrease the spatial extent of the EA sulfate influence over the North Pacific both at the surface and at 500 mb in all seasons, but the extent of influence is insensitive to emission increases, particularly in DJF and JJA. We find that EA sulfate concentrations over most downwind regions respond nearly linearly to changes in EA SO2 emissions, but sulfate concentrations over the EA source region increase more slowly than SO2 emissions, particularly at the surface and in winter, due to limited availability of oxidants (mostly H2O2). We find that similar estimates of the S-R relationship for trans-Pacific transport of EA sulfate would be obtained using either sensitivity or tagging techniques. Our findings suggest that future changes in EA sulfur emissions may cause little change in the sulfate induced health impact over downwind continents but SO2 emission reductions may significantly reduce the sulfate related climate cooling over the North Pacific and the United States.

BREAKING GRAVITY WAVES ON A JET STREAM OVER THE NORTH PACIFIC

Weather ◽  
1971 ◽  
Vol 26 (7) ◽  
pp. 306-307 ◽  
Author(s):  
J. R. C. Young
Keyword(s):  
Gravity Waves ◽  
North Pacific ◽  
Jet Stream ◽  
The North ◽  
The North Pacific

A Role for Barotropic Eddy–Mean Flow Feedbacks in the Zonal Wind Response to Sea Ice Loss and Arctic Amplification

2019 ◽  
Vol 32 (21) ◽  
pp. 7469-7481 ◽  
Author(s):  
Bryn Ronalds ◽  
Elizabeth A. Barnes
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Zonal Wind ◽  
Jet Stream ◽  
Arctic Amplification ◽  
Mean Flow ◽  
Jet Streams ◽  
The North ◽  
Wind Response ◽  
The North Pacific

Abstract Previous studies have suggested that, in the zonal mean, the climatological Northern Hemisphere wintertime eddy-driven jet streams will weaken and shift equatorward in response to Arctic amplification and sea ice loss. However, multiple studies have also pointed out that this response has strong regional differences across the two ocean basins, with the North Atlantic jet stream generally weakening across models and the North Pacific jet stream showing signs of strengthening. Based on the zonal wind response with a fully coupled model, this work sets up two case studies using a barotropic model to test a dynamical mechanism that can explain the differences in zonal wind response in the North Pacific versus the North Atlantic. Results indicate that the differences between the two basins are due, at least in part, to differences in the proximity of the jet streams to the sea ice loss, and that in both cases the eddies act to increase the jet speed via changes in wave breaking location and frequency. Thus, while baroclinic arguments may account for an initial reduction in the midlatitude winds through thermal wind balance, eddy–mean flow feedbacks are likely instrumental in determining the final total response and actually act to strengthen the eddy-driven jet stream.

Sign in / Sign up

Export Citation Format

Share Document