scholarly journals Boreal Winter Links between the Madden–Julian Oscillation and the Arctic Oscillation

2008 ◽  
Vol 21 (12) ◽  
pp. 3040-3050 ◽  
Author(s):  
Michelle L. L’Heureux ◽  
R. Wayne Higgins
Keyword(s):  
Arctic Oscillation ◽  
Active Phase ◽  
Temperature Fields ◽  
The Arctic ◽  
Boreal Winter ◽  
Madden Julian Oscillation ◽  
Global Circulation ◽  
Leading Mode ◽  
The Arctic Oscillation ◽  
The Tropics

Abstract There is increasing evidence that the Madden–Julian oscillation (MJO) modifies the mid- to high-latitude circulation and, in particular, appears to have a relationship to the leading mode of extratropical variability, the Arctic Oscillation (AO). In this study, new insights into the observed similarities between the MJO and the AO are explored. It is shown that the eastward progression of the convectively active phase of the MJO is associated with a corresponding shift in the tendency and sign of the AO index. Moreover, the AO and the MJO share several analogous features not only in the global circulation, but also in surface temperature fields. Also, the AO is linked to a pattern of eastward-propagating MJO-like variability in the tropics that is partially reproduced in free runs of the NCEP Climate Forecast System (CFS) model. Finally, it is shown that the structure of the AO, as defined by the leading mode in the 1000-hPa geopotential height field, is significantly altered based on the phase of the MJO.

scholarly journals Interaction between the MJO and Polar Circulations

2013 ◽  
Vol 26 (11) ◽  
pp. 3562-3574 ◽  
Author(s):  
Maria Flatau ◽  
Young-Joon Kim
Keyword(s):  
Indian Ocean ◽  
Southern Hemisphere ◽  
Warm Season ◽  
Cold Season ◽  
The Arctic ◽  
Boreal Winter ◽  
Annular Modes ◽  
The Indian Ocean ◽  
The Arctic Oscillation ◽  
The Tropics

Abstract A tropical–polar connection and its seasonal dependence are examined using the real-time multivariate Madden–Julian oscillation (MJO) (RMM) index and daily indices for the annular modes, the Arctic Oscillation (AO) and the Antarctic Oscillation (AAO). On the intraseasonal time scale, the MJO appears to force the annular modes in both hemispheres. On this scale, during the cold season, the convection in the Indian Ocean precedes the increase of the AO/AAO. Interestingly, during the boreal winter (Southern Hemisphere warm season), strong MJOs in the Indian Ocean are related to a decrease of the AAO index, and AO/AAO tendencies are out of phase. On the longer time scales, a persistent AO/AAO anomaly appears to influence the convection in the tropical belt and impact the distribution of MJO-preferred phases. It is shown that this may be a result of the sea surface temperature (SST) changes related to a persistent AO, with cooling over the Indian Ocean and warming over Indonesia. In the Southern Hemisphere, the SST anomalies are to some extent also related to a persistent AAO pattern, but this relationship is much weaker and appears only during the Southern Hemisphere cold season. On the basis of these results, a mechanism involving the air–sea interaction in the tropics is suggested as a possible link between persistent AO and convective activity in the Indian Ocean and western Pacific.

Association of Indian Ocean ITCZ Variations with the Arctic Oscillation during Boreal Winter

2013 ◽  
Vol 6 (5) ◽  
pp. 300-305
Author(s):  
Gong Dao-Yi ◽  
Gao Yong-Qi ◽  
Hu Miao ◽  
Guo Dong
Keyword(s):  
Indian Ocean ◽  
Arctic Oscillation ◽  
The Arctic ◽  
Boreal Winter ◽  
The Arctic Oscillation

scholarly journals Where can the Arctic oscillation be reconstructed? Towards a reconstruction of climate modes based on stable teleconnections

2005 ◽  
Vol 1 (1) ◽  
pp. 17-56 ◽  
Author(s):  
G. Lohmann ◽  
N. Rimbu ◽  
M. Dima
Keyword(s):  
Arctic Oscillation ◽  
Ice Core ◽  
The Arctic ◽  
Boreal Winter ◽  
Arctic Oscillation Index ◽  
Climate Modes ◽  
Teleconnection Patterns ◽  
Temperature And Precipitation ◽  
The Arctic Oscillation ◽  
Coral Tree

Abstract. Proxy data can bring observed climate variability of the last 100 years into a long-term context. We identify regions of the Northern Hemisphere where the teleconnection patterns of the Arctic Oscillation are stationary. Our method provides a systematic way to examine optimal sites for the reconstruction of climate modes based on paleoclimatic archives that sensitively record temperature and precipitation variations. We identify the regions for boreal winter and spring that can be used to reconstruct the Arctic Oscillation index in the pre-instrumental period. Finally, this technique is applied to high resolution coral, tree ring, ice core and mollusk shell data to understand proxy-climate teleconnections and their use for climate reconstructions.

scholarly journals Interannual Variability of the North American Cold Air Stream and Associated Synoptic Circulations

2017 ◽  
Vol 30 (23) ◽  
pp. 9575-9590 ◽  
Author(s):  
Yuki Kanno ◽  
John E. Walsh ◽  
Toshiki Iwasaki
Keyword(s):  
United States ◽  
Interannual Variability ◽  
Rocky Mountains ◽  
Arctic Oscillation ◽  
Potential Temperature ◽  
The Arctic ◽  
Boreal Winter ◽  
Stratospheric Polar Vortex ◽  
Cold Air ◽  
The Arctic Oscillation

In boreal winter, the cold air mass (CAM) flux of air with a potential temperature below 280 K forms climatological mean CAM streams in East Asia and North America (NA). This study diagnoses the interannual variability of the NA stream by an analysis of the CAM flux across 60°N between Greenland and the Rocky Mountains. The first empirical orthogonal function (EOF) represents the variations in intensity of the NA stream. When the first principal component (PC1) is highly positive, the central part of the NA stream is intensified, with cold anomalies east of the Rocky Mountains. At the same time, a stratospheric polar vortex tends to split or displace toward NA. PC1 is highly correlated with the tropical Northern Hemisphere pattern, implying that this pattern is associated with the intensity of the NA stream. The second EOF shows a longitudinal shift of the NA stream toward Greenland or the Rocky Mountains. A highly negative PC2 results in a cold anomaly from western Canada to the Midwestern United States and anomalous heavy snowfall in the northeastern United States. PC2 is positively correlated with the Arctic Oscillation, which suggests that the longitudinal position of the NA stream varies with the Arctic Oscillation. These results illustrate how the intensity and location of cold air outbreaks vary with large-scale modes of atmospheric variability, with corresponding implications for the predictability of winter severity in NA.

scholarly journals The Interaction of the Madden–Julian Oscillation and the Arctic Oscillation

2005 ◽  
Vol 18 (1) ◽  
pp. 143-159 ◽  
Author(s):  
Shuntai Zhou ◽  
Alvin J. Miller
Keyword(s):  
Large Scale ◽  
Arctic Oscillation ◽  
Winter Season ◽  
The Arctic ◽  
Height Anomaly ◽  
Madden Julian Oscillation ◽  
Regional Effect ◽  
The Pacific ◽  
Action Center ◽  
The Arctic Oscillation

Abstract Tropical and extratropical interactions on the intraseasonal time scale are studied in the context of the Arctic Oscillation (AO) and the Madden–Julian oscillation (MJO). To simplify the discussion, a high (low) MJO phase is defined as strong (suppressed) convective activity over the Indian Ocean. In the Northern Hemisphere (NH) winter season, a high (low) AO phase is found more likely coupled with a high (low) MJO phase. Based on the regressed patterns and composites of various dynamical fields and quantities, possible mechanisms linking the AO and the MJO are examined. The analysis indicates that the MJO influence on extratropical circulations seems more evident than the AO influence on tropical circulations. The MJO interacts with the AO through meridional dispersion of Rossby waves in the Pacific sector. The geopotential height anomaly center over the North Pacific associated with the MJO can either reinforce or offset the AO Pacific action center. As a result, the AO pattern can be greatly affected by the MJO. When the AO and the MJO are in the same (opposite) phase, the Pacific action center becomes much stronger (weaker) than the Atlantic action center. The eddy momentum transports associated with the MJO in the Pacific sector are closely related to the retraction and extension of tropical Pacific easterlies and the subtropical Asian–Pacific jet. Because of its large scale, this regional effect is also reflected in the zonal mean state of wave transport and wave forcing on zonal wind, which in turn affects the phase of the AO.

scholarly journals Influence of the Madden–Julian Oscillation on the Arctic Oscillation Prediction in S2S Operational Models

2021 ◽  
Vol 9 ◽  
Author(s):  
Yang Zhou ◽  
Yang Wang
Keyword(s):  
Arctic Oscillation ◽  
Time Lag ◽  
Prediction Skill ◽  
The Arctic ◽  
Negative Phase ◽  
Initial Time ◽  
Madden Julian Oscillation ◽  
Global Circulation Models ◽  
The Arctic Oscillation ◽  
The Relationship

The connections between the Madden–Julian Oscillation (MJO) and the Arctic Oscillation (AO) are examined in both observations and model forecasts. In the observations, the time-lag composites are carried out for AO indices and anomalies of 1,000-hPa geopotential height after an active or inactive initial MJO. The results show that when the AO is in its positive (negative) phase at the initial time, the AO activity is generally enhanced (weakened) after an active MJO. Reforecast data of the 11 operational global circulation models from the Sub-seasonal to Seasonal (S2S) Prediction Project are further used to examine the relationship between MJO activity and AO prediction. When the AO is in its positive phase on the initial day of the S2S prediction, an initial active MJO can generally improve the AO prediction skill in most of the models. This is consistent with results found in the observations that a leading MJO can enhance the AO activity. However, when the AO is in its negative phase, the relationship between the MJO and AO prediction is not consistent among the 11 models. Only a few S2S models provide results that agree with the observations. Furthermore, the S2S prediction skill of the AO is examined in different MJO phases. There is a significantly positive relationship between the MJO-related AO activity and the AO prediction skill. When the AO activity is strong (weak) in an MJO phase, including the inactive MJO, the models tend to have a high (low) AO prediction skill. For example, no matter what phase the initial AO is in, the AO prediction skill is generally high in MJO phase 7, in which the AO activity is generally strong. Thus, the MJO is an important predictability source for the AO forecast in the S2S models.

scholarly journals Modulation of the Westerly and Easterly Quasi-Biennial Oscillation Phases on the Connection between the Madden–Julian Oscillation and the Arctic Oscillation

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 175 ◽  
Author(s):  
Lei Song ◽  
Renguang Wu
Keyword(s):  
Rossby Wave ◽  
Arctic Oscillation ◽  
Wave Train ◽  
The Arctic ◽  
Madden Julian Oscillation ◽  
Quasi Biennial Oscillation ◽  
Rossby Wave Train ◽  
Asian Pacific ◽  
The Arctic Oscillation ◽  
Biennial Oscillation

Previous studies have revealed the relationship between the Madden–Julian oscillation (MJO) and the Arctic Oscillation (AO). The MJO phase 2/3 is followed by the positive AO phase, and the MJO phase 6/7 is followed by the negative AO phase. This study reveals that the MJO phase 6/7–AO connection is modulated by the Quasi-Biennial Oscillation (QBO) through both tropospheric and stratospheric pathways during boreal winter. The MJO 2/3 phase and AO relationship is favored in both QBO easterly (QBOE) and westerly (QBOW) years because of the MJO-triggered tropospheric Rossby wave train from the tropics toward the polar region. The AO following the MJO 6/7 phase shifts to negative in QBOW years, but the MJO–AO connection diminishes in QBOE years. In QBOW years, the Asian-Pacific jet is enhanced, leading to more evident poleward propagation of tropospheric Rossby wave train, which contributes to the tropospheric pathway of the AO–MJO 6/7 connection. Besides, the enhanced Asian-Pacific jet in QBOW years is favorable for vertical propagation of planetary waves into the stratosphere in MJO phase 6/7, leading to negative AO, which indicates the stratospheric pathway of the AO–MJO 6/7 connection.

Why Northeast China Has a Cooling Trend in 21st century?

2020 ◽  
Author(s):  
Xiang Li ◽  
Hui Gao
Keyword(s):  
Northeast China ◽  
Eastern China ◽  
Negative Temperature ◽  
Significant Negative Correlation ◽  
Empirical Orthogonal Functions ◽  
The Arctic ◽  
Boreal Winter ◽  
Orthogonal Functions ◽  
Leading Mode ◽  
The Arctic Oscillation

<p>    Under the global warming scenarios, the air temperatures (T<sub>2m</sub>) in China in boreal winter shows a remarkable increasing trend since the 1980s, which is quite similar with the change of the globe. But in Northeast China (NEC), the temperature displays an opposite characteristics with an obvious decreasing trend in recent two decades. Results of the empirical orthogonal functions (EOF) of T<sub>2m</sub> in China indicate that the first leading mode is a consistent positive or negative temperature departures in the whole country, but the variance of this mode show a weakening tendency. The second leading mode of T<sub>2m</sub> in China shows a seesaw temperature anomaly pattern in NEC and in other regions of eastern China. Different from the 1<sup>st</sup> EOF mode, variances of this mode show an intensifying tendency. Both statistical analysis and case studies of 20 winters during 2000 to 2019 indicate that this opposite change in NEC may be related to the decadal relationship between the Siberian high and the Arctic oscillation. Previous studies explored that there was a significant negative correlation between the two factors, but this relationship was significantly weakened in the past two decades, which led to the independent influences from the two circulation members on the temperature in NEC, and consequently resulted in an inconsistent variation in the region.</p>

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