scholarly journals Combined effect of the Arctic Oscillation and the Western Pacific pattern on East Asia winter temperature

2015 ◽  
Vol 46 (9-10) ◽  
pp. 3205-3221 ◽  
Author(s):  
Hye-Jin Park ◽  
Joong-Bae Ahn
Keyword(s):  
East Asia ◽  
Arctic Oscillation ◽  
Winter Temperature ◽  
Combined Effect ◽  
Western Pacific ◽  
The Arctic ◽  
The Arctic Oscillation ◽  
The Western Pacific ◽  
Western Pacific Pattern

scholarly journals Relationship between the Arctic Oscillation and Cold Surges over East Asia

2011 ◽  
Vol 24 (1) ◽  
pp. 68-83 ◽  
Author(s):  
Tae-Won Park ◽  
Chang-Hoi Ho ◽  
Song Yang
Keyword(s):  
East Asia ◽  
Arctic Oscillation ◽  
Wave Train ◽  
The Arctic ◽  
Aleutian Low ◽  
Cold Surge ◽  
Dipole Structure ◽  
Cold Surges ◽  
The Arctic Oscillation ◽  
Blocking Type

Abstract The present study reveals the changes in the characteristics of cold surges over East Asia associated with the Arctic Oscillation (AO). Based on circulation features, cold surges are grouped into two general types: wave train and blocking types. The blocking type of cold surge tends to occur during negative AO periods, that is, the AO-related polarity of the blocking type. However, the wave train type is observed during both positive and negative AO periods, although the wave train features associated with negative AO are relatively weaker. The cold surges during negative AO are stronger than those during positive AO in terms of both amplitude and duration. The cold surges during positive AO in which the extent of effect is confined to inland China passes through East Asia quickly because of weaker Siberian high and Aleutian low, leading to short duration of these cold surges. In contrast, the cold surge during negative AO, characterized by a well-organized anticyclone–cyclone couplet with high pressure over continental East Asia and low pressure over Japan, brings continuous cold air into the entire East Asian region for more than one week with long-lasting cold advection. It is also found that the tracks of the cold surges during negative AO tend to occur more frequently over Korea and Japan and less frequently over China, compared with those during positive AO. The tracks are related to a west–east dipole structure of the ratio of rain conversion to snow according to AO phase, resulting in freezing precipitation or snowfall events over inland China (Korea and Japan) are likely to occur more frequently during the positive (negative) AO periods.

scholarly journals Frequency Associations between East Asian Jet Streams and the Temperature over the Barents–Kara Sea Region/Arctic Oscillation in Winter

Climate ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 107
Author(s):  
Yuefeng Li ◽  
Yuxiang Zhu ◽  
Wei Song
Keyword(s):  
East Asia ◽  
Arctic Oscillation ◽  
East Asian ◽  
Kara Sea ◽  
Wavelet Coherence ◽  
The Arctic ◽  
Jet Stream ◽  
Jet Streams ◽  
The Arctic Oscillation ◽  
Cross Wavelet

The frequency associations between jet streams over East Asia and the Arctic key temperature at 2 m (AKT2m) in the Barents–Kara Sea region (40°–75° E, 66°–82° N) and the Arctic Oscillation in winter are investigated using continuous wavelet transform, cross-wavelet transform, and wavelet coherence. The cross-wavelet transforms between the AKT2m/Arctic Oscillation and the East Asian polar front jet stream (EAPJ) suggest that the EAPJ is closely related to the AKT2m and Arctic Oscillation on an interannual (3–5-year band) timescale, but the variation in the phase angle denotes a complex frequency connection between the EAPJ and Arctic Oscillation. The squared wavelet coherence suggests that weakening of the EAPJ is associated with the rise in AKT2m during the period of abrupt climate change in East Asia. The EAPJ contains more forced components from the Arctic than the East Asian subtropical jet stream. By comparison, the relationship between AKT2m and the EAPJ is closer than that between the Arctic Oscillation and EAPJ, especially during the period of abrupt climate change in East Asia. This suggests that the EAPJ serves as a bridge for Arctic warming to affect the weather and climate over East Asia in winter. By contrast, the Arctic Oscillation does not play an important part, although it also contains information about the Arctic.

scholarly journals Combined Effects of the MJO and the Arctic Oscillation on the Intraseasonal Eastern China Winter Temperature Variations

2019 ◽  
Vol 32 (8) ◽  
pp. 2295-2311 ◽  
Author(s):  
Lei Song ◽  
Renguang Wu
Keyword(s):  
East Asia ◽  
High Latitude ◽  
Western Europe ◽  
Arctic Oscillation ◽  
Wave Train ◽  
Eastern China ◽  
The Arctic ◽  
Wave Source ◽  
Temperature Anomalies ◽  
The Arctic Oscillation

AbstractThe present study reveals that the Madden–Julian oscillation (MJO)-related temperature anomalies over East Asia have notable differences among positive, neutral, and negative Arctic Oscillation (AO) phases. In MJO phases 2–3, cold anomalies over eastern China occur mainly during positive AO. In MJO phase 7, warm anomalies over eastern China are observed mostly during neutral AO, and in MJO phase 8 warm anomalies appear in positive and neutral AO. Regional mean temperature anomalies over northeastern East Asia tend to be negative during negative AO but positive during positive AO in six of eight MJO phases. In MJO phases 2–3, the AO-related mid- to high-latitude wave train over Eurasia and the MJO convection-triggered poleward wave train work together in contributing to negative height anomalies over eastern China and leading to cold anomalies there. The mid- to high-latitude wave train is stronger when the AO is negative than positive, which is associated with stronger zonal winds. In MJO phases 7–8, the positive AO-related mid- to high-latitude wave train over Eurasia and the MJO-induced poleward wave train cooperate in inducing positive height anomalies and leading to warm anomalies over eastern China. The mid- to high-latitude wave train is the main contributor to negative height anomalies over eastern China when the AO is negative during MJO phases 7–8. Meanwhile, the intensity of the South Asian wave source associated with the MJO convection is subjected to the modulation of southeastward dispersion of wave energy from western Europe during negative AO.

Comparisons of different definitions of the western Pacific pattern and associated winter climate anomalies in Eurasia and North America

2020 ◽  
Author(s):  
Hasi Aru
Keyword(s):  
North America ◽  
Air Temperature ◽  
Southern Oscillation ◽  
Surface Air Temperature ◽  
Western Pacific ◽  
The Arctic ◽  
Temperature Anomalies ◽  
The Western Pacific ◽  
Air Temperature Anomalies ◽  
Western Pacific Pattern

<p>The western Pacific pattern (WP) is one of the most prominent teleconnection patterns over the Northern Hemisphere (NH) in boreal winter. There exist several methods employed to identify the WP in the literature. This study compares eight WPs defined by different methods. Correlation coefficients among the eight WP indices (WPIs) show considerable spreads, though most of them are statistically significant. The meridional dipole structure of WP can be captured by all of the WPIs, but it shows large spreads in the locations of the centers. Several WPIs produce a significant correlation with the winter Arctic Oscillation, with marked signals of atmospheric anomalies over the Arctic region. Connections of the WPs with the simultaneous winter El Niño-Southern Oscillation (ENSO) depend largely upon their definitions. Impacts of the WPs on the surface air temperature over many parts of Eurasia and North America are also sensitive to their definitions. Differences in the surface air temperature anomalies are closely related to differences in the spatial structure of the WPs. Finally, we define a new WP index as differences in the area-average 500-hPa geopotential height anomalies between subtropics and mid-latitude of northwestern Pacific. This newly defined WP index has a close relation with the above eight WPIs, the tropical Pacific sea surface temperature and surface air temperature anomalies over Eurasia and North America.</p>

scholarly journals Beryllium-7 and Lead-210 are Associated with an Increase in the Arctic Oscillation: Evidence from Atmospheric Aerosols in a Remote Tropical Region in East Asia

2021 ◽  
Author(s):  
Xiaoxia Chen ◽  
Wuhui Lin ◽  
Xianwen He ◽  
Liangliang Feng ◽  
Kuo-Ying Wang
Keyword(s):  
East Asia ◽  
High Latitude ◽  
Arctic Oscillation ◽  
Meteorological Data ◽  
Large Fraction ◽  
The Arctic ◽  
Tropical Region ◽  
Monitoring Site ◽  
High Latitudes ◽  
The Arctic Oscillation

AbstractThe Arctic Oscillation (AO) accounts for a large fraction of recent decadal climate trends in Northern Hemisphere (NH) high latitudes. In East Asia, an elevated AO index (AOI) was associated with warmer temperatures in middle- to high-latitude regions, colder temperatures over low-latitude regions, and elevated ozone intrusion from the stratosphere. Elevated beryllium-7 (7Be) is produced in the stratosphere. Few studies have discussed the relationship between 7Be and the AO. Here, we identify the AO signature in 7Be and lead (Pb)-210 observed at a tropical ambient monitoring site in Nanning (22.8°N, 108.5°E) during the December 2014–December 2017 period. Our results show that the 7Be and 210Pb concentrations are positively and significantly correlated with the AOI (P < 0.01). These results show that elevated 7Be and 210Pb are associated with an increase in the AOI, reflecting air masses originating from NH high latitudes and vertically from the high-latitude upper troposphere and lower stratosphere regions to tropical latitudes in East Asia. These results have been verified with ozonesonde data without seasonality and with two meteorological data sets. Our results are also confirmed by observational data over the Pacific regions. We conclude that the AO exerts impacts over the tropical regions in East Asia, and 7Be can be used as a tracer to track the impacts of the AO.

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