Bay of Bengal‐East Asia‐Pacific Teleconnection in Boreal Summer

2020 ◽  
Author(s):  
Jie Cao
Keyword(s):  
Surface Temperature ◽  
East Asia ◽  
Bay Of Bengal ◽  
Reanalysis Data ◽  
Teleconnection Pattern ◽  
Early Summer ◽  
Boreal Summer ◽  
Flux Analysis ◽  
Weather Forecasts ◽  
Wave Flux

<p>A new teleconnection pattern (the BEAP) across the Bay of Bengal‐East Asia‐Pacific region in boreal summer is revealed in this study using mainly ERA‐Interim reanalysis data from the European Centre for Medium‐Range Weather Forecasts. The BEAP index (BEAPI) is defined as the signed sum of standardized apparent moisture sinks at five centers along the pathway. Correlation analysis of the apparent heat sources and apparent moisture sinks has verified the existence of the BEAP teleconnection. Variations in BEAP can affect precipitation anomalies resulting from the anomalous moisture transport and the antiphase surface temperature variation. Wave flux analysis has verified the Rossby wave propagation route that originates around the central Bay of Bengal and extends across North China to the West Pacific. La Niña‐type sea surface temperature anomalies (SSTAs) appearing simultaneously in the same season can excite a positive BEAP pattern by enhancing convection over the Bay of Bengal, while El Niño‐type SSTAs have the opposite effect. Significant correlation between the BEAPI and the SSTAs can last from early summer to early winter. Numerical experiments confirm the BEAP teleconnection pattern and the associated physical processes.</p>

scholarly journals Bay of Bengal‐East Asia‐Pacific Teleconnection in Boreal Summer

2019 ◽  
Vol 124 (8) ◽  
pp. 4395-4412 ◽  
Author(s):  
Ruowen Yang ◽  
Shu Gui ◽  
Jie Cao
Keyword(s):  
East Asia ◽  
Bay Of Bengal ◽  
Asia Pacific ◽  
Boreal Summer

Quasi-Biweekly Oscillation of the Bay of Bengal–East Asia–Pacific Teleconnection in Boreal Summer

2020 ◽  
Vol 33 (17) ◽  
pp. 7643-7662
Author(s):  
Shu Gui ◽  
Ruowen Yang
Keyword(s):  
East Asia ◽  
Bay Of Bengal ◽  
Intraseasonal Variability ◽  
Intraseasonal Oscillation ◽  
Vertical Motion ◽  
Phase Changes ◽  
Asia Pacific ◽  
Dynamical Analysis ◽  
Extreme Weather Events ◽  
Boreal Summer

AbstractThe study reported in this paper used ERA-Interim reanalysis data to investigate the intraseasonal variability of the Bay of Bengal (BOB)–East Asia–Pacific teleconnection (BEAP) during the summer between 1979 and 2016. Over this period, the intraseasonal oscillation of the BEAP fell mainly within the quasi-biweekly oscillation (QBWO) band. Variations in atmospheric circulation and precipitation, which may contribute to extreme weather events, showed a significant correlation with the phase transition of the BEAP from the BOB to East Asia and the Pacific. The evolution of the BEAP–QBWO is closely associated with the westward propagation of convective anomalies to the southwestern BOB. Dynamical analysis revealed that anomalous vertical motion coupled with anomalous convective activity over the southern BOB plays an important role in leading the phase propagation of the BEAP–QBWO, and that the horizontal advection anomalies can strengthen the BEAP–QBWO. Linear baroclinic model experiments confirmed that variations in convection over the southern BOB play a leading role in the BEAP–QBWO phase changes. Further research suggests that the boreal summer intraseasonal oscillation can trigger the BEAP–QBWO through downstream propagation of convective disturbances to the southern BOB. This study provides insights into the cause and effect of the BEAP–QBWO, which will help to improve understanding of flood and drought patterns in the Asia–Pacific region.

scholarly journals Weakened Connection between East China Summer Rainfall and the East Asia-Pacific Teleconnection Pattern

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 704
Author(s):  
Xiaoxue Yin ◽  
Lian-Tong Zhou ◽  
Jingliang Huangfu
Keyword(s):  
East Asia ◽  
Vertical Motion ◽  
Summer Rainfall ◽  
Teleconnection Pattern ◽  
Asia Pacific ◽  
East China ◽  
Boreal Summer ◽  
Interdecadal Change ◽  
Rainfall Anomalies ◽  
Action Center

The interdecadal change in the relationship between the East Asia-Pacific (EAP) teleconnection pattern and rainfall over East China during boreal summer (June–August) was investigated using observation and reanalysis datasets during 1951–2018. As proposed in a previous study, summer rainfall in the Yangtze-Huaihe River (YH-R) valley is below (above) normal when a positive (negative) EAP event occurs. Based on the close relationship with the rainfall anomalies, the EAP teleconnection pattern has been widely used in the prediction of summer rainfall variations in the YH-R valley. However, we found that the rainfall anomalies in the YH-R basin associated with the EAP pattern were weaker and less evident after the late 1980s. This finding indicates a decreased relationship between the EAP pattern and YH-R basin summer rainfall after the late 1980s, and a decrease in the quality and skill of seasonal predictions of YH-R basin summer rainfall related to the EAP pattern. This pronounced weakening in the YH-R summer rainfall-EAP pattern connection is attributed to the northeastward displacement of the Japanese action center of the EAP pattern after the late 1980s, which caused weaker anomalous vertical motion and moisture transportation over the YH-R valley. The present research reveals that the interdecadal expansion in the size of the Indo-Pacific warm pool in the late 1980s is likely responsible for the northeastward shift in the Japanese action center of the EAP teleconnection pattern by modulating anomalous convective activities and the northward propagation of the EAP pattern.

Forcing Processes of the Summertime Circumglobal Teleconnection Pattern in a Dry AGCM

2010 ◽  
Vol 23 (8) ◽  
pp. 2093-2114 ◽  
Author(s):  
Soichiro Yasui ◽  
Masahiro Watanabe
Keyword(s):  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Low Frequency ◽  
Atmospheric Model ◽  
Meridional Wind ◽  
Reanalysis Data ◽  
Teleconnection Pattern ◽  
Boreal Summer ◽  
Potential Predictability ◽  
Circumglobal Teleconnection

Abstract To better understand the predictability of the wavelike circumglobal teleconnection (CGT) pattern prevailing during boreal summer, two sets of experiments are performed using a nonlinear dry atmospheric model. Each experiment consists of a 10-member ensemble of 26-yr integrations driven by the diabatic heating derived from reanalysis data: one with the monthly climatological mean heating (CLIM) and the other with the monthly heating for 1979–2004 (HIST). Both do well in reproducing the observed summer mean state, as well as the low-frequency variance distribution. The CGT pattern identified in the monthly meridional wind anomalies at 200 hPa shows zonally oriented wave packets over Eurasia. The simulated CGT has a nearly identical phase structure with the observations and indicates little difference between the CLIM and HIST results. While this indicates that the origin of CGT lies in the internal dry dynamics, the ensemble mean of the CGT in HIST is partly controlled by the slow variation in the heating field, as indicated by the high potential predictability of the simulated CGT pattern. Diagnoses using the linearized model demonstrate that the heating anomaly most responsible for the CGT-like steady response is located over the eastern Mediterranean region, where the heating may be coupled with the CGT pattern. In addition to the heating near the CGT, remote heating and cooling anomalies over North America and equatorial Africa are found to be effective at exciting stationary Rossby waves trapped on the Atlantic and Asian jets. It is thus suggested that the mechanisms generating the heating anomalies over these regions are the key to the predictability of the CGT pattern.

scholarly journals Avaliação do modelo regional climático para a previsão de temperatura no centro de lançamento de Alcântara

2021 ◽  
Vol 3 (5) ◽  
pp. 2908-2921
Author(s):  
Alexandre Santos De Souza ◽  
Cleber Souza Correa ◽  
Inácio Malmonge Martin
Keyword(s):  
Surface Temperature ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Reanalysis Data ◽  
Operations Planning ◽  
Weather Forecasts ◽  
Average Maximum ◽  
Medium Range ◽  
Maximum Temperatures

Este estudo avaliou a previsão intrasazonal da temperatura à superfície (2 m de altura) na região do Centro de Lançamento de Alcântara (CLA) utilizando O Regional Climate Model RegCM4.7 em comparação aos dados de reanálises obtidos do modelo de reanalises globalERA5 do European Centre for Medium-Range Weather Forecasts (ECMWF) para os meses de abril de 2019 (estação chuvosa) e outubro de 2019 (estação seca). Foram realizadas 4 (quatro) membros de simulações de temperatura utilizando o RegCM4.7 em horários sinóticos, os quais foram comparadas com os dados observacionais e de reanálises do ERA5. Os resultados indicaram uma boa previsibilidade para a temperatura média nos dois períodos, diferenças inferiores a 1 °C, com um grau de diferença para abril e praticamente coincidindo em outubro. Para as temperaturas máximas médias o RegCM4.7 superestimou em 2 °C para abril e 4 °C para outubro. Para as temperaturas médias mínimas subestimou em 2 °C tanto para abril como para outubro. Essas avaliações indicaram um bom desempenho geral para a previsão de temperaturas médias, contudo, sabendo-se da tendência de superestimar temperaturas máximas médias e subestimar temperaturas mínimas médias, ainda assim, com as devidas correções, poderá ser utilizado com eficácia para a previsão intrasazonal de temperatura à superfície em apoio ao planejamento de operações de lançamento no CLA.   This study evaluated the intraseasonal surface temperature (2 m height) forecast in the Alcântara Launch Center (ALC) region using the Regional Climate Model RegCM4.7 against reanalysis data obtained from the European Center for Medium-Range Weather global Forecasts (ECMWF) reanalysis model ERA5 for the months of April 2019 (rainy season) and October 2019 (dry season). Four members of temperature simulations were performed using RegCM4.7 at synoptic times, which were compared with observational and reanalysis data from ERA5. The results indicated a good predictability for the average temperature in the two periods, differences below 1 °C, with one degree of difference for April and practically coinciding in October. For average maximum temperatures RegCM4.7 overestimated by 2 °C for April and 4 °C for October. For average minimum temperatures, it was underestimated by 2 °C for both April and October. These evaluations indicated a good overall performance for predicting average temperatures, however, knowing the tendency to overestimate average maximum temperatures and underestimate average minimum temperatures, even so, with the appropriate corrections, it can be used effectively for forecasting intraseasonal surface temperature analysis in support of ALC launch operations planning.  

scholarly journals Influence of East Asia Pacific Teleconnection and Scandinavian Teleconnection on Summer Precipitation in Southwest China

2021 ◽  
Author(s):  
mingxin yang ◽  
Tiangui Xiao ◽  
Ping Zhao ◽  
Yong Li ◽  
Wei Huang ◽  
...  
Keyword(s):  
East Asia ◽  
Southwest China ◽  
Summer Precipitation ◽  
Significant Negative Correlation ◽  
Reanalysis Data ◽  
Teleconnection Pattern ◽  
Asia Pacific ◽  
The South ◽  
Teleconnection Patterns ◽  
The North

Abstract Based on the summer precipitation data of 328 stations in Southwest China in 50 years and the reanalysis data of NCEP / NCAR monthly geopotential height field, and wind field, the relationship between summer precipitation in Southwest China and East Asia Pacific teleconnection pattern (EAP) and Scandinavian teleconnection pattern (SCA) is explored by using EOF, correlation analysis and synthetic analysis. The research results show that: the summer precipitation distribution in Southwest China is mainly divided into two types: the whole region consistent type and the north-south contrary type. EAP teleconnection patterns and SCA teleconnection patterns have a significant negative correlation with the precipitation in Southwest China during the same period. In the active year (teleconnection indices >= 0.3 or <= 0.3), the two teleconnection patterns mostly appear in the same phase, and the distribution of the precipitation is consistent with the second mode distribution of the EOF for summer precipitation in Southwest China, showing a north-south contrary distribution in Southwest China. The two types of teleconnections are divided into two configurations, both of which are positive phase (configuration I), and both are negative phase (configuration II). Configuration I, the summer precipitation in Southwest China presents the distribution of "more in the south and less in the north"; configuration II, the distribution of precipitation is opposite to that configuration I, showing the distribution of "more in the north and less in the south".

Atmospheric teleconnection patterns associated with severe and mild ice cover on the Great Lakes, 1963–2011

2012 ◽  
Vol 47 (3-4) ◽  
pp. 421-435 ◽  
Author(s):  
Xuezhi Bai ◽  
Jia Wang
Keyword(s):  
North America ◽  
Great Lakes ◽  
El Niño ◽  
El Nino ◽  
Ice Cover ◽  
Reanalysis Data ◽  
Teleconnection Pattern ◽  
La Niña ◽  
Atmospheric Teleconnection ◽  
La Nina

Atmospheric teleconnection circulation patterns associated with severe and mild ice cover over the Great Lakes are investigated using the composite analysis of lake ice data and National Center of Environmental Prediction (NCEP) reanalysis data for the period 1963–2011. The teleconnection pattern associated with the severe ice cover is the combination of a negative North Atlantic Oscillation (NAO) or Arctic Oscillation (AO) and negative phase of Pacific/North America (PNA) pattern, while the pattern associated with the mild ice cover is the combination of a positive PNA (or an El Niño) and a positive phase of the NAO/AO. These two extreme ice conditions are associated with the North American ridge–trough variations. The intensified ridge–trough system produces a strong northwest-to-southeast tilted ridge and trough and increases the anomalous northwesterly wind, advecting cold, dry Arctic air to the Great Lakes. The weakened ridge–trough system produces a flattened ridge and trough, and promotes a climatological westerly wind, advecting warm, dry air from western North America to the Great Lakes. Although ice cover for all the individual lakes responds roughly linearly and symmetrically to both phases of the NAO/AO, and roughly nonlinearly and asymmetrically to El Niño and La Niña events, the overall ice cover response to individual NAO/AO or Niño3.4 index is not statistically significant. The combined NAO/AO and Niño3.4 indices can be used to reliably project severe ice cover during the simultaneous –NAO/AO and La Niña events, and mild ice cover during the simultaneous +NAO/AO and El Niño events.

scholarly journals Interannual Variability and Trends in Sea Surface Temperature, Lower and Middle Atmosphere Temperature at Different Latitudes for 1980–2019

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 454
Author(s):  
Andrew R. Jakovlev ◽  
Sergei P. Smyshlyaev ◽  
Vener Y. Galin
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Lower Stratosphere ◽  
Middle Atmosphere ◽  
Southern Oscillation ◽  
Lower Troposphere ◽  
Reanalysis Data ◽  
Sea Surface ◽  
The Arctic ◽  
The Impact

The influence of sea-surface temperature (SST) on the lower troposphere and lower stratosphere temperature in the tropical, middle, and polar latitudes is studied for 1980–2019 based on the MERRA2, ERA5, and Met Office reanalysis data, and numerical modeling with a chemistry-climate model (CCM) of the lower and middle atmosphere. The variability of SST is analyzed according to Met Office and ERA5 data, while the variability of atmospheric temperature is investigated according to MERRA2 and ERA5 data. Analysis of sea surface temperature trends based on reanalysis data revealed that a significant positive SST trend of about 0.1 degrees per decade is observed over the globe. In the middle latitudes of the Northern Hemisphere, the trend (about 0.2 degrees per decade) is 2 times higher than the global average, and 5 times higher than in the Southern Hemisphere (about 0.04 degrees per decade). At polar latitudes, opposite SST trends are observed in the Arctic (positive) and Antarctic (negative). The impact of the El Niño Southern Oscillation phenomenon on the temperature of the lower and middle atmosphere in the middle and polar latitudes of the Northern and Southern Hemispheres is discussed. To assess the relative influence of SST, CO2, and other greenhouse gases’ variability on the temperature of the lower troposphere and lower stratosphere, numerical calculations with a CCM were performed for several scenarios of accounting for the SST and carbon dioxide variability. The results of numerical experiments with a CCM demonstrated that the influence of SST prevails in the troposphere, while for the stratosphere, an increase in the CO2 content plays the most important role.

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