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.

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.

Wintertime North Pacific Teleconnection Patterns: Seasonal and Interannual Variability

2015 ◽  
Vol 28 (20) ◽  
pp. 8247-8263 ◽  
Author(s):  
Jiacan Yuan ◽  
Benkui Tan ◽  
Steven B. Feldstein ◽  
Sukyoung Lee
Keyword(s):  
Sea Ice ◽  
Interannual Variability ◽  
North Pacific ◽  
Southern Oscillation ◽  
Late Winter ◽  
Self Organizing Map ◽  
Teleconnection Patterns ◽  
The North ◽  
Seasonal Shift ◽  
The North Pacific

Abstract The teleconnections of the wintertime North Pacific are examined from the continuum perspective with self-organizing map (SOM) analysis. Daily ERA-Interim data for the 1979–2011 period are used. It is found that most of the North Pacific teleconnections can be grouped into several Pacific–North American (PNA)-like, western Pacific (WP)-like, and east Pacific (EP)-like SOM patterns. Each of the SOM patterns has an e-folding time scale of 7–10 days. The WP-like SOM patterns undergo a decline in their frequency from early to late winter, and vice versa for the EP-like SOM patterns, corresponding to an eastward seasonal shift of the North Pacific teleconnections. This seasonal shift is observed for both phases of the WP and EP patterns, and is only weakly sensitive to the phase of El Niño–Southern Oscillation. It is shown that the interannual variability of the PNA, WP, and EP can be interpreted as arising from interannual changes in the frequency of the corresponding SOM patterns. The WP- and EP-like SOM patterns are found to be associated with statistically significant sea ice cover anomalies over the Sea of Okhotsk and the Bering Sea. The low-level wind and temperature anomalies associated with these patterns are consistent with the changes in sea ice arising from both wind-driven sea ice motion and freezing and/or melting of sea ice due to horizontal temperature advection. Furthermore, widespread precipitation anomalies over the North Pacific are found for all three patterns.

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.

scholarly journals Influence of Wintertime Polar Vortex Variation on the Climate over the North Pacific during Late Winter and Spring

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 670 ◽  
Author(s):  
Kequan Zhang ◽  
Tao Wang ◽  
Mian Xu ◽  
Jiankai Zhang
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Geopotential Height ◽  
North Pacific Ocean ◽  
Polar Vortex ◽  
Late Winter ◽  
Stratospheric Polar Vortex ◽  
The North ◽  
The North Pacific ◽  
The Bering Sea

The effects of wintertime stratospheric polar vortex variation on the climate over the North Pacific Ocean during late winter and spring are analyzed using the National Centers for Environmental Predictions, version 2 (NCEP2) reanalysis dataset. The analysis revealed that, during weak polar vortex (WPV) events, there are noticeably lower geopotential height anomalies over the Bering Sea and greater height anomalies over the central part of the North Pacific Ocean than during strong polar vortex (SPV) events. The formation of the dipolar structure of the geopotential height anomalies is due to a weakened polar jet and a strengthened mid-latitude jet in the troposphere via geostrophic equilibrium. The mechanisms responsible for the changes in the tropospheric jet over the North Pacific Ocean are summarized as follows: when the stratospheric polar westerly is decelerated, the high-latitude eastward waves slow down, and the enhanced equatorward propagation of the eddy momentum flux throughout the troposphere at 60° N. Consequently, the eddy-driven jet over the North Pacific Ocean also shows a southward displacement, leading to a weaker polar jet but a stronger mid-latitude westerly compared with those during the SPV events. Furthermore, anomalous anti-cyclonic flows associated with the higher pressure over the North Pacific Ocean during WPV events induce a warming sea surface temperature (SST) over the western and central parts of the North Pacific Ocean and a cooling SST over the Bering Sea and along the west coast of North America. This SST pattern can last until May, which favors the persistence of the anti-cyclonic flows over the North Pacific Ocean during WPV events. A well-resolved stratosphere and coupled atmosphere-ocean model (CMCC-CMS) can basically reproduce the impacts of stratospheric polar vortex variations on the North Pacific climate as seen in NCEP2 data, although the simulated dipole of geopotential height anomalies is shifted more southward.

Model Biases in the Simulation of the Springtime North Pacific ENSO Teleconnection

2020 ◽  
Vol 33 (23) ◽  
pp. 9985-10002
Author(s):  
Ruyan Chen ◽  
Isla R. Simpson ◽  
Clara Deser ◽  
Bin Wang
Keyword(s):  
El Niño ◽  
North Pacific ◽  
Climate Models ◽  
El Nino ◽  
Coupled Model ◽  
La Niña ◽  
Late Winter ◽  
The North ◽  
La Nina ◽  
The North Pacific

AbstractThe wintertime ENSO teleconnection over the North Pacific region consists of an intensified (weakened) low pressure center during El Niño (La Niña) events both in observations and in climate models. Here, it is demonstrated that this teleconnection persists too strongly into late winter and spring in the Community Earth System Model (CESM). This discrepancy arises in both fully coupled and atmosphere-only configurations, when observed SSTs are specified, and is shown to be robust when accounting for the sampling uncertainty due to internal variability. Furthermore, a similar problem is found in many other models from piControl simulations of the Coupled Model Intercomparison Project (23 out of 43 in phase 5 and 11 out of 20 in phase 6). The implications of this bias for the simulation of surface climate anomalies over North America are assessed. The overall effect on the ENSO composite field (El Niño minus La Niña) resembles an overly prolonged influence of ENSO into the spring with anomalously high temperatures over Alaska and western Canada, and wet (dry) biases over California (southwest Canada). Further studies are still needed to disentangle the relative roles played by diabatic heating, background flow, and other possible contributions in determining the overly strong springtime ENSO teleconnection intensity over the North Pacific.

Different Impacts of the East Asian Winter Monsoon on the Surface Air Temperature in North America during ENSO and Neutral ENSO Years

2020 ◽  
Vol 33 (24) ◽  
pp. 10671-10690
Author(s):  
Tianjiao Ma ◽  
Wen Chen ◽  
Hans-F. Graf ◽  
Shuoyi Ding ◽  
Peiqiang Xu ◽  
...  
Keyword(s):  
Wave Packet ◽  
North Pacific ◽  
East Asian Winter Monsoon ◽  
East Asian ◽  
Surface Air Temperature ◽  
Winter Monsoon ◽  
Asian Winter Monsoon ◽  
The North ◽  
The North Pacific ◽  
Central North Pacific

AbstractThe present study investigates different impacts of the East Asian winter monsoon (EAWM) on surface air temperature (Ts) in North America (NA) during ENSO and neutral ENSO episodes. In neutral ENSO years, the EAWM shows a direct impact on the Ts anomalies in NA on an interannual time scale. Two Rossby wave packets appear over the Eurasian–western Pacific (upstream) and North Pacific–NA (downstream) regions associated with a strong EAWM. Further analysis suggests that the downstream wave packet is caused by reflection of the upstream wave packet over the subtropical western Pacific and amplified over the North Pacific. Also, the East Asian subtropical westerly jet stream (EAJS) is intensified in the central and downstream region over the central North Pacific. Hence, increased barotropic kinetic energy conversion and the interaction between transient eddies and the EAJS tend to maintain the circulation anomaly over the North Pacific. Therefore, a strong EAWM tends to result in warm Ts anomalies in northwestern NA via the downstream wave packet emanating from the central North Pacific toward NA. A weak EAWM tends to induce cold Ts anomalies in western-central NA with a smaller magnitude. However, in ENSO years, an anomalous EAJS is mainly confined over East Asia and does not extend into the central North Pacific. The results confirm that the EAWM has an indirect impact on the Ts anomalies in NA via a modulation of the tropical convection anomalies associated with ENSO. Our results indicate that, for seasonal prediction of Ts anomalies in NA, the influence of the EAWM should be taken into account. It produces different responses in neutral ENSO and in ENSO years.

scholarly journals East Asian dust storm in May 2017: observations, modelling, and its influence on the Asia-Pacific region

2018 ◽  
Vol 18 (11) ◽  
pp. 8353-8371 ◽  
Author(s):  
Xiao-Xiao Zhang ◽  
Brenton Sharratt ◽  
Lian-You Liu ◽  
Zi-Fa Wang ◽  
Xiao-Le Pan ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Dust Storm ◽  
North Pacific ◽  
East Asian ◽  
Asian Dust ◽  
Asia Pacific ◽  
Gobi Desert ◽  
Dust Event ◽  
The North ◽  
The North Pacific

Abstract. A severe dust storm event originated from the Gobi Desert in Central and East Asia during 2–7 May 2017. Based on Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products, hourly environmental monitoring measurements from Chinese cities and East Asian meteorological observation stations, and numerical simulations, we analysed the spatial and temporal characteristics of this dust event as well as its associated impact on the Asia-Pacific region. The maximum observed hourly PM10 (particulate matter with an aerodynamic diameter ≤ 10 µm) concentration was above 1000 µg m−3 in Beijing, Tianjin, Shijiazhuang, Baoding, and Langfang and above 2000 µg m−3 in Erdos, Hohhot, Baotou, and Alxa in northern China. This dust event affected over 8.35 million km2, or 87 % of the Chinese mainland, and significantly deteriorated air quality in 316 cities of the 367 cities examined across China. The maximum surface wind speed during the dust storm was 23–24 m s−1 in the Mongolian Gobi Desert and 20–22 m s−1 in central Inner Mongolia, indicating the potential source regions of this dust event. Lidar-derived vertical dust profiles in Beijing, Seoul, and Tokyo indicated dust aerosols were uplifted to an altitude of 1.5–3.5 km, whereas simulations by the Weather Research and Forecasting with Chemistry (WRF-Chem) model indicated 20.4 and 5.3 Tg of aeolian dust being deposited respectively across continental Asia and the North Pacific Ocean. According to forward trajectory analysis by the FLEXible PARTicle dispersion (FLEXPART) model, the East Asian dust plume moved across the North Pacific within a week. Dust concentrations decreased from the East Asian continent across the Pacific Ocean from a magnitude of 103 to 10−5 µg m−3, while dust deposition intensity ranged from 104 to 10−1 mg m−2. This dust event was unusual due to its impact on continental China, the Korean Peninsula, Japan, and the North Pacific Ocean. Asian dust storms such as those observed in early May 2017 may lead to wider climate forcing on a global scale.

scholarly journals Dust transport from non-East Asian sources to the North Pacific

2012 ◽  
Vol 39 (12) ◽  
pp. n/a-n/a ◽  
Author(s):  
Shih-Chieh Hsu ◽  
Chih-An Huh ◽  
Chuan-Yao Lin ◽  
Wei-Nai Chen ◽  
Natalie M. Mahowald ◽  
...  
Keyword(s):  
North Pacific ◽  
East Asian ◽  
Dust Transport ◽  
The North ◽  
The North Pacific
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