scholarly journals The Victoria mode in the North Pacific linking extratropical sea level pressure variations to ENSO

2015 ◽  
Vol 120 (1) ◽  
pp. 27-45 ◽  
Author(s):  
Ruiqiang Ding ◽  
Jianping Li ◽  
Yu-heng Tseng ◽  
Cheng Sun ◽  
Yipeng Guo
Keyword(s):  
Sea Level ◽  
North Pacific ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The North ◽  
The North Pacific

scholarly journals Future changes in Beijing haze events under different anthropogenic aerosol emission scenarios

2021 ◽  
Vol 21 (10) ◽  
pp. 7499-7514
Author(s):  
Lixia Zhang ◽  
Laura J. Wilcox ◽  
Nick J. Dunstone ◽  
David J. Paynter ◽  
Shuai Hu ◽  
...  
Keyword(s):  
Sea Level ◽  
Atmospheric Circulation ◽  
North Pacific ◽  
Anthropogenic Aerosol ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The North ◽  
Aerosol Emission ◽  
Circulation Patterns ◽  
The North Pacific

Abstract. Air pollution is a major issue in China and one of the largest threats to public health. We investigated future changes in atmospheric circulation patterns associated with haze events in the Beijing region and the severity of haze events during these circulation conditions from 2015 to 2049 under two different aerosol scenarios: a maximum technically feasible aerosol reduction (MTFR) and a current legislation aerosol scenario (CLE). In both cases greenhouse gas emissions follow the Representative Concentration Pathway 4.5 (RCP4.5). Under RCP4.5 with CLE aerosol the frequency of circulation patterns associated with haze events increases due to a weakening of the East Asian winter monsoon via increased sea level pressure over the North Pacific. The rapid reduction in anthropogenic aerosol and precursor emissions in MTFR further increases the frequency of circulation patterns associated with haze events, due to further increases in the sea level pressure over the North Pacific and a reduction in the intensity of the Siberian high. Even with the aggressive aerosol reductions in MTFR periods of poor visibility, represented by above-normal aerosol optical depth (AOD), still occur in conjunction with haze-favorable atmospheric circulation. However, the winter mean intensity of poor visibility decreases in MTFR, so that haze events are less dangerous in this scenario by 2050 compared to CLE and relative to the current baseline. This study reveals the competing effects of aerosol emission reductions on future haze events through their direct contribution to pollutant source and their influence on the atmospheric circulation. A compound consideration of these two impacts should be taken in future policy making.

The North Pacific Climate Transitions of the Winters of 1976/77 and 1988/89

2011 ◽  
Vol 24 (4) ◽  
pp. 1170-1183 ◽  
Author(s):  
Sang-Wook Yeh ◽  
Yune-Jung Kang ◽  
Yign Noh ◽  
Arthur J. Miller
Keyword(s):  
Sea Level ◽  
North Pacific ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The North ◽  
Sst Variability ◽  
Transition Project ◽  
Climate Transition ◽  
The Tropics ◽  
The North Pacific

Abstract This paper examines characteristic changes in North Pacific sea surface temperature (SST) variability during the boreal winter (December–February) for two subperiods (1956–88 and 1977–2009) during which the 1976/77 and the 1988/89 climate transitions occurred. It is found that the Pacific decadal oscillation (PDO)-like SST variability plays a dominant role in the 1976/77 climate transition, while both the North Pacific Gyre Oscillation (NPGO)-like and PDO-like SST variability contribute to the 1988/89 climate transition. Furthermore, the leading mode changes from PDO-like SST variability during the period 1956–88 to NPGO-like SST variability during the period 1977–2009, indicative of an enhancement of NPGO-like SST variability since 1988. Changes in sea level pressure across the 1976/77 climate transition project strongly onto the Aleutian low pressure system. But sea level pressure changes across the 1988/89 climate transition project primarily onto the North Pacific Oscillation, which is associated with remote changes in the Arctic Oscillation over the polar region as well. This contributes to enhancing the NPGO-like SST variability after 1988. The authors also analyze the output from an ensemble of Tropical Ocean and Global Atmosphere (TOGA) experiments in which the observed SSTs are inserted only at grid points in the tropics between 20°S and 20°N. The results indicate that the changes in the North Pacific atmosphere in the 1976/77 climate transition are mostly due to the tropics, whereas those in the 1988/89 climate transition are not.

scholarly journals New Insights into Annual and Semiannual Cycles of Sea Level Pressure

2012 ◽  
Vol 140 (4) ◽  
pp. 1347-1355 ◽  
Author(s):  
Ge Chen ◽  
Chengcheng Qian ◽  
Caiyun Zhang
Keyword(s):  
Sea Level ◽  
Southern Oscillation ◽  
Global Ocean ◽  
Boreal Winter ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The North ◽  
Dominant Feature ◽  
The One ◽  
The North Pacific

Sea level pressure (SLP) acts, on the one hand, as a “bridge parameter” to which geophysical properties at the air–sea interface (e.g., wind stress and sea surface height) are linked, and on the other hand, as an “index parameter” by which major atmospheric oscillations, including the well-known Southern Oscillation, are defined. Using 144 yr (1854–1997) of extended reconstructed SLP data, seasonal patterns of its variability are reinvestigated in detail. New features on fundamental structure of its annual and semiannual cycles are revealed in two aspects. First, the spatiotemporal patterns of yearly and half-yearly SLPs are basically determined by a network of “amphidromes,” which are surrounded by rotational variations. Fourteen cyclonic and anticyclonic annual SLP amphidromes (half each and often in pair) are found in the global ocean, while the numbers of the two types of semiannual amphidrome are 11 and 9, respectively. The second dominant feature in SLP variability is the pattern of oscillation or seesaw for both annual and semiannual components. At least eight oscillation zones are identified for the annual cycle, which can be categorized into a boreal winter mode and an austral winter mode. As for the semiannual cycle, the seesaw pattern is geographically divided into three regimes: the North Pacific regime, the North Atlantic regime, and the Southern Ocean regime. These findings serve as a new contribution to characterizing and understanding the seasonality of the global ocean–atmosphere system.

Tropospheric Precursors and Stratospheric Warmings

2011 ◽  
Vol 24 (24) ◽  
pp. 6562-6572 ◽  
Author(s):  
Judah Cohen ◽  
Justin Jones
Keyword(s):  
Sea Level ◽  
Energy Flux ◽  
Polar Vortex ◽  
Stratospheric Warming ◽  
Sea Level Pressure ◽  
Winter Climate ◽  
Level Pressure ◽  
The North ◽  
Tropospheric Circulation ◽  
The North Pacific

Abstract Many tropospheric Arctic Oscillation (AO) events are preceded by stratospheric AO events and even earlier in time by anomalous upward energy flux associated with Rossby waves in the troposphere. This study identifies lower-tropospheric circulation anomalies that precede large AO events in both the troposphere and stratosphere and the anomalous upward energy flux. Compositing analysis of stratospheric warming events identifies regional tropospheric precursors, which precede stratospheric warmings. The tropospheric precursor is found to vary when compositing over polar vortex displacements and splits separately. Prior to vortex displacements the main anomaly sea level pressure center of the tropospheric precursor is located across northwest Eurasia and is associated with the Siberian high. Prior to vortex splits a similar anomaly center is identified in the tropospheric precursor but is weaker and appears to be more strongly related to a shift in the storm tracks. Differences in the sea level pressure anomalies in the North Atlantic and the North Pacific are also observed when comparing the precursors prior to vortex displacements and splits. Identification of a unique tropospheric precursor to stratospheric warming and subsequent tropospheric AO events can help to improve understanding troposphere–stratosphere coupling. Furthermore, the observational evidence presented here can be compared with model simulations of winter climate variability and lead to potential model improvements.

The Continuum of North Pacific Sea Level Pressure Patterns: Intraseasonal, Interannual, and Interdecadal Variability

2010 ◽  
Vol 23 (4) ◽  
pp. 851-867 ◽  
Author(s):  
Nathaniel C. Johnson ◽  
Steven B. Feldstein
Keyword(s):  
Sea Level ◽  
Frequency Distribution ◽  
Time Scales ◽  
North Pacific ◽  
Interdecadal Variability ◽  
Sea Level Pressure ◽  
The North ◽  
Pressure Anomaly ◽  
The North Pacific ◽  
The Continuum

Abstract This study combines k-means cluster analysis with linear unidimensional scaling to illustrate the spatial and temporal variability of the wintertime North Pacific sea level pressure (SLP) field. Daily wintertime SLP data derived from the NCEP–NCAR reanalysis are used to produce 16 SLP anomaly patterns that represent a discretized approximation of the continuum of North Pacific SLP patterns. This study adopts the continuum perspective for teleconnection patterns, which provides a much simpler framework for understanding North Pacific variability than the more commonly used discrete modal approach. The primary focus of this research is to show that variability in the North Pacific—on intraseasonal, interannual, and interdecadal time scales—can be understood in terms of changes in the frequency distribution of the cluster patterns that compose the continuum, each of which has a time scale of about 10 days. This analysis reveals 5–6 Pacific–North American–like (PNA-like) patterns for each phase, as well as dipoles and wave trains. A self-organizing map (SOM) analysis of coupled SLP and outgoing longwave radiation data shows that many of these patterns are associated with convection in the tropical Indo-Pacific region. On intraseasonal time scales, the frequency distribution of these patterns, in particular the PNA-like patterns, is strongly influenced by the Madden–Julian oscillation (MJO). On interannual time scales, the El Niño–Southern Oscillation (ENSO) impacts the North Pacific continuum, with warm ENSO episodes resulting in the increased frequency of easterly displaced Aleutian low pressure anomaly patterns and cold ENSO episodes resulting in the increased frequency of southerly displaced Aleutian high pressure anomaly patterns. In addition, the results of this analysis suggest that the interdecadal variability of the North Pacific SLP field, including the well-known “regime shift” of 1976/77, also results from changes in the frequency distribution within the continuum of SLP patterns.

scholarly journals Future changes in Beijing haze events under different anthropogenic aerosol emission scenarios

2020 ◽  
Author(s):  
Lixia Zhang ◽  
Laura J. Wilcox ◽  
Nick J. Dunstone ◽  
David J. Paynter ◽  
Shuai Hu ◽  
...  
Keyword(s):  
Sea Level ◽  
Atmospheric Circulation ◽  
North Pacific ◽  
Anthropogenic Aerosol ◽  
Sea Level Pressure ◽  
Atmospheric Circulation Patterns ◽  
The North ◽  
Aerosol Emission ◽  
Circulation Patterns ◽  
The North Pacific

Abstract. Air pollution is a major issue in China and one of the largest threats to public health. We investigated future changes in atmospheric circulation patterns associated with haze events in the Beijing region, and the severity of haze events during these circulation conditions, from 2016 to 2049 under two different aerosol scenarios: a maximum technically feasible aerosol reduction (MTFR) and a current legislation aerosol scenario (CLE). In both cases greenhouse gas emissions follow the Representative Concentration Pathway (RCP) 4.5. Under RCP4.5 with CLE aerosol the frequency of circulation patterns associated with haze events increases due to a weakening of the East Asian winter monsoon via increased sea level pressure over the North Pacific. The rapid reduction in anthropogenic aerosol and precursor emissions in MTFR further increases the frequency of circulation patterns associated with haze events, due to further increases of the sea level pressure over the North Pacific and a reduction in the intensity of the Siberian high. Even with the aggressive aerosol reductions in MTFR periods of poor visibility, represented by above normal aerosol optical depth (AOD), still occur in conjunction with atmospheric circulation patterns currently associated with haze in the current climate. However, the intensity of poor visibility decreases in MTFR, so that haze events are less dangerous in this scenario by 2050 compared to CLE, and relative to the current baseline. This study reveals the competing effects of aerosol emission reductions on future haze events through their direct contribution to haze and their influence on the atmospheric circulation patterns. A compound consideration of these two impacts should be taken in future policy making.

scholarly journals The Influences of the Atlantic Multidecadal Oscillation on the Mean Strength of the North Pacific Subtropical High during Boreal Winter

2017 ◽  
Vol 30 (1) ◽  
pp. 411-426 ◽  
Author(s):  
Kewei Lyu ◽  
Jin-Yi Yu ◽  
Houk Paek
Keyword(s):  
Sea Level ◽  
North Pacific ◽  
Stationary Wave ◽  
Atlantic Multidecadal Oscillation ◽  
Wave Pattern ◽  
Subtropical High ◽  
Sea Level Pressure ◽  
The North ◽  
The Pacific ◽  
The North Pacific

The Atlantic multidecadal oscillation (AMO) has been shown to be capable of exerting significant influences on the Pacific climate. In this study, the authors analyze reanalysis datasets and conduct forced and coupled experiments with an atmospheric general circulation model (AGCM) to explain why the winter North Pacific subtropical high strengthens and expands northwestward during the positive phase of the AMO. The results show that the tropical Atlantic warming associated with the positive AMO phase leads to a westward displacement of the Pacific Walker circulation and a cooling of the tropical Pacific Ocean, thereby inducing anomalous descending motion over the central tropical Pacific. The descending motion then excites a stationary Rossby wave pattern that extends northward to produce a nearly barotropic anticyclone over the North Pacific. A diagnosis based on the quasigeostrophic vertical velocity equation reveals that the stationary wave pattern also results in enhanced subsidence over the northeastern Pacific via the anomalous advections of vorticity and temperature. The anomalous barotropic anticyclone and the enhanced subsidence are the two mechanisms that increase the sea level pressure over the North Pacific. The latter mechanism occurs to the southeast of the former one and thus is more influential in the subtropical high region. Both mechanisms can be produced in forced and coupled AGCMs but are displaced northward as a result of stationary wave patterns that differ from those observed. This explains why the model-simulated North Pacific sea level pressure responses to the AMO tend to be biased northward.

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