scholarly journals The Interdecadal Variations and Causes of the Relationship Between Autumn Precipitation Anomalies in Eastern China and SSTA Over the Southeastern Tropical Indian Ocean

2021 ◽  
Author(s):  
Liwei Huo ◽  
Zhaoyong Guan ◽  
Dachao Jin ◽  
Xi Liu ◽  
Xudong Wang ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Eastern China ◽  
Tropical Indian Ocean ◽  
The Other ◽  
Drought Event ◽  
Low Level ◽  
Rainfall Anomalies ◽  
Precipitation Anomalies ◽  
The Relationship ◽  
Southeastern Tropical Indian Ocean

Abstract Eastern China has a large population with rapid development of the economy, where is the important crop producing region. In this region, the spatial and temporal distribution of autumn rainfall in Eastern China is uneven, which has important societal impact. Using the NCEP–NCAR reanalysis and other observational datasets, it is found that the spatial distribution of the first EOF mode of autumn rainfall anomalies in eastern China is consistent across the region, with significant interannual variabilities. Pronounced interdecadal variations are presented in the relationship between autumn rainfall anomalies in eastern China and sea-surface temperature anomalies (SSTA) over the southeastern tropical Indian Ocean (SETIO). The interdecadal changes have been analyzed by considering two epochs: one during 1979-2004 and the other during 2005-2019. It shows weak and insignificant correlations between the autumn rainfall anomalies in eastern China and SSTA over SETIO during the first epoch. On the other hand, they are remarkable and positively correlated with each other during the second epoch. The inter-decadal changes of the above relationship are related to the warming of SST over SETIO during the second epoch. It causes stronger low-level convergence and ascending motion over SETIO, with the co-occurrence of enhanced western Pacific subtropical high and anomalous abundant moisture over eastern China carried by a low-level southerly anomaly originating from the South China Sea. Simultaneously, the local Hadley circulation over eastern China becomes weak, corresponding to the anomalous ascending motion. The collaboration of anomalous water vapour transport and ascending motion strengthens the connection between the SETIO SSTA and the autumn precipitation anomalies in eastern China, and vice versa. In the boreal autumn of 2019, entire eastern China suffered extreme drought. It suggests that this drought event in eastern China is strongly affected by the negative SSTA over SETIO, which is consistent with the statistical results.

scholarly journals Breakdown of the Relationship between Australian Summer Rainfall and ENSO Caused by Tropical Indian Ocean SST Warming

2018 ◽  
Vol 31 (6) ◽  
pp. 2321-2336 ◽  
Author(s):  
Zhiwei Zhu
Keyword(s):  
Indian Ocean ◽  
Tropical Indian Ocean ◽  
Summer Rainfall ◽  
La Niña ◽  
Maritime Continent ◽  
La Nina ◽  
Sst Warming ◽  
The Indian Ocean ◽  
Rainfall Anomalies ◽  
The Relationship

The relationship between El Niño–Southern Oscillation (ENSO) and Australian summer rainfall (ASR) during 1960–2015 experienced an interdecadal change around the mid-1980s. Before the mid-1980s, ASR was significantly correlated with tropical central Pacific (TCP) sea surface temperature (SST), whereas after that it was not. While El Niño was always independent from ASR, La Niña had a close relationship with ASR. However, this relationship was weakened after the mid-1980s. The Indian Ocean SST warming might contribute to the weakening relationship between La Niña and ASR. For La Niña events before the mid-1980s, the negative SSTA over TCP and the southern tropical Indian Ocean induced a large-scale lower-level cyclonic anomaly over Australia, leading to nearly uniform positive precipitation over Australia. In this manner, a significant relationship between ASR and La Niña was established. On the contrary, for the La Niña events after the mid-1980s, because of the Indian Ocean SST warming, the equatorial eastern Indian Ocean and Maritime Continent presented positive SSTAs and enhanced moisture, favoring enhanced rainfall anomalies over the equatorial Maritime Continent. This enhanced rainfall condensation heating induced a lower-level cyclonic anomaly to the west of Australia. The northerly anomalies at the eastern flank of this cyclonic anomaly counteracted the southerly anomalies at the western flank of the cyclonic anomaly over eastern Australia induced by the negative TCP SSTA, leading to insignificant circulation and rainfall anomalies over Australia. As such, being interfered with by the equatorial Maritime Continent heating, the relationship between ASR and La Niña was weakened.

scholarly journals El Niño-Southern Oscillation and Indian Ocean Dipole Modes: Their Effects on South American Rainfall during Austral Spring

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1437
Author(s):  
Mary T. Kayano ◽  
Wilmar L. Cerón ◽  
Rita V. Andreoli ◽  
Rodrigo A. F. Souza ◽  
Itamara P. Souza ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Indian Ocean ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Austral Spring ◽  
Precipitation Anomalies

This paper examines the effects of the tropical Pacific Ocean (TPO) and Indian Ocean Dipole (IOD) modes in the interannual variations of austral spring rainfall over South America (SA). The TPO mode refers to the El Niño-Southern Oscillation (ENSO). The isolated effects between IOD and TPO were estimated, events were chosen from the residual TPO (R-TPO) or residual IOD (R-IOD), and the IOD (TPO) effects for the R-TPO (R-IOD) composites were removed from the variables. One relevant result was the nonlinear precipitation response to R-TPO and R-IOD. This feature was accentuated for the R-IOD composites. The positive R-IOD composite showed significant negative precipitation anomalies along equatorial SA east of 55° W and in subtropical western SA, and showed positive anomalies in northwestern SA and central Brazil. The negative R-IOD composite indicated significant positive precipitation anomalies in northwestern Amazon, central–eastern Brazil north of 20° S, and western subtropical SA, and negative anomalies were found in western SA south of 30° S. This nonlinearity was likely due to the distinct atmospheric circulation responses to the anomalous heating sources located in longitudinally distinct regions: the western tropical Indian Ocean and areas neighboring Indonesia. The results obtained in this study might be relevant for climate monitoring and modeling studies.

scholarly journals Possible Impact of the Indian Ocean SST on the Northern Hemisphere Circulation during El Niño*

2007 ◽  
Vol 20 (13) ◽  
pp. 3164-3189 ◽  
Author(s):  
H. Annamalai ◽  
H. Okajima ◽  
M. Watanabe
Keyword(s):  
Indian Ocean ◽  
Northern Hemisphere ◽  
El Niño ◽  
El Nino ◽  
Tropical Indian Ocean ◽  
Tropical Pacific ◽  
The Indian Ocean ◽  
Precipitation Anomalies ◽  
Sst Anomalies ◽  
The Tropical Pacific

Abstract Two atmospheric general circulation models (AGCMs), differing in numerics and physical parameterizations, are employed to test the hypothesis that El Niño–induced sea surface temperature (SST) anomalies in the tropical Indian Ocean impact considerably the Northern Hemisphere extratropical circulation anomalies during boreal winter [January–March +1 (JFM +1)] of El Niño years. The hypothesis grew out of recent findings that ocean dynamics influence SST variations over the southwest Indian Ocean (SWIO), and these in turn impact local precipitation. A set of ensemble simulations with the AGCMs was carried out to assess the combined and individual effects of tropical Pacific and Indian Ocean SST anomalies on the extratropical circulation. To elucidate the dynamics responsible for the teleconnection, solutions were sought from a linear version of one of the AGCMs. Both AGCMs demonstrate that the observed precipitation anomalies over the SWIO are determined by local SST anomalies. Analysis of the circulation response shows that over the Pacific–North American (PNA) region, the 500-hPa height anomalies, forced by Indian Ocean SST anomalies, oppose and destructively interfere with those forced by tropical Pacific SST anomalies. The model results validated with reanalysis data show that compared to the runs where only the tropical Pacific SST anomalies are specified, the root-mean-square error of the height anomalies over the PNA region is significantly reduced in runs in which the SST anomalies in the Indian Ocean are prescribed in addition to those in the tropical Pacific. Among the ensemble members, both precipitation anomalies over the SWIO and the 500-hPa height over the PNA region show high potential predictability. The solutions from the linear model indicate that the Rossby wave packets involved in setting up the teleconnection between the SWIO and the PNA region have a propagation path that is quite different from the classical El Niño–PNA linkage. The results of idealized experiments indicate that the Northern Hemisphere extratropical response to Indian Ocean SST anomalies is significant and the effect of this response needs to be considered in understanding the PNA pattern during El Niño years. The results presented herein suggest that the tropical Indian Ocean plays an active role in climate variability and that accurate observation of SST there is of urgent need.

scholarly journals Interannual Climate Variability over the Tropical Pacific Ocean Induced by the Indian Ocean Dipole through the Indonesian Throughflow

2013 ◽  
Vol 26 (9) ◽  
pp. 2845-2861 ◽  
Author(s):  
Dongliang Yuan ◽  
Hui Zhou ◽  
Xia Zhao
Keyword(s):  
Pacific Ocean ◽  
Indian Ocean ◽  
Tropical Indian Ocean ◽  
Sea Surface Height ◽  
Equatorial Pacific ◽  
Sea Surface ◽  
Indonesian Throughflow ◽  
Cold Tongue ◽  
The Indian Ocean ◽  
Southeastern Tropical Indian Ocean

Abstract The authors’ previous dynamical study has suggested a link between the Indian and Pacific Ocean interannual climate variations through the transport variations of the Indonesian Throughflow. In this study, the consistency of this oceanic channel link with observations is investigated using correlation analyses of observed ocean temperature, sea surface height, and surface wind data. The analyses show significant lag correlations between the sea surface temperature anomalies (SSTA) in the southeastern tropical Indian Ocean in fall and those in the eastern Pacific cold tongue in the following summer through fall seasons, suggesting potential predictability of ENSO events beyond the period of 1 yr. The dynamics of this teleconnection seem not through the atmospheric bridge, because the wind anomalies in the far western equatorial Pacific in fall have insignificant correlations with the cold tongue anomalies at time lags beyond one season. Correlation analyses between the sea surface height anomalies (SSHA) in the southeastern tropical Indian Ocean and those over the Indo-Pacific basin suggest eastward propagation of the upwelling anomalies from the Indian Ocean into the equatorial Pacific Ocean through the Indonesian Seas. Correlations in the subsurface temperature in the equatorial vertical section of the Pacific Ocean confirm the propagation. In spite of the limitation of the short time series of observations available, the study seems to suggest that the ocean channel connection between the two basins is important for the evolution and predictability of ENSO.

scholarly journals Seasonal Characteristics of Circulation in the Southeastern Tropical Indian Ocean*

2005 ◽  
Vol 35 (2) ◽  
pp. 255-267 ◽  
Author(s):  
Tangdong Qu ◽  
Gary Meyers
Keyword(s):  
Indian Ocean ◽  
Annual Variation ◽  
Maximum Amplitude ◽  
Tropical Indian Ocean ◽  
Surface Flow ◽  
Sea Surface ◽  
The South ◽  
Near Surface ◽  
Seasonal Characteristics ◽  
Southeastern Tropical Indian Ocean

Abstract The circulation in the southeastern tropical Indian Ocean is studied using historical temperature and salinity data. A southward shift of the subtropical gyre at increasing depth dominates the structure of the annual mean circulation. Near the southern Indonesian coast the westward South Equatorial Current (SEC) is at the sea surface and strongest near 10°–11°S, reflecting strong influence of the Indonesian Throughflow (ITF). In latitudes 13°–25°S the SEC is a subsurface flow and its velocity core deepens toward the south, falling below 500 m at 25°S. The eastern gyral current (EGC) is a surface flow overlying the SEC, associated with the meridional gradients of near-surface temperature and salinity. The ITF supplies water to the SEC mainly in the upper 400 m, and below that depth the flow is reversed along the coast of Sumatra and Java. Monsoon winds strongly force the annual variation in circulation. Dynamic height at the sea surface has a maximum amplitude at 10°–13°S, and the maximum at deeper levels is located farther south. Annual variation is also strong in the coastal waveguides, but is mainly confined to the near-surface layer. Although the South Java Current at the sea surface is not well resolved in the present dataset, semiannual variation is markedly evident at depth and tends to extend much deeper than the annual variation along the coast of Sumatra and Java.

scholarly journals Evolution of two troughs in the tropical Indian Ocean and their characteristic features

MAUSAM ◽  
2021 ◽  
Vol 43 (4) ◽  
pp. 395-398
Author(s):  
M.S. SINGH ◽  
B. Lakshmanaswamy
Keyword(s):  
Indian Ocean ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
South Asian ◽  
Tropical Indian Ocean ◽  
The Other ◽  
The South ◽  
The Indian Ocean ◽  
Characteristic Features

Evolution and characteristic features of double trough systems in the tropical Indian Ocean have been studied with the help of Climatological Atlas (Part I andIl) ~f the Tropical Indian Oc.ean (Hastenrath and Lamb 1979). It is confirmed that there are two troughs (Northern Hemisphere EquatorIal Trough and Southern Hemisphere Equatorial Trough) in this region (including south Asian landmass) all the year round, one in northern hemisphere and the other in southern. Both are migratory in nature and, perhaps, thermal in origin.  In the convergent zones of the two troughs, there is extensive cloudiness. The migration of these trough systems during their respective summer seasons appear to be related to the extensive heating of the south Asian/ African land masses surrounding the Indian Ocean in north and west.  

scholarly journals Nutrient enrichment induced by tropical cyclone Seroja in the southeastern tropical Indian Ocean

2021 ◽  
Vol 925 (1) ◽  
pp. 012021
Author(s):  
D W Purnaningtyas ◽  
F Khadami ◽  
Avrionesti
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Nutrient Enrichment ◽  
Tropical Indian Ocean ◽  
Sea Surface ◽  
Nutrient Concentrations ◽  
Biochemical Alterations ◽  
Southeastern Tropical Indian Ocean

Abstract Tropical cyclone (TC) passage triggers a complex response from the adjacent ocean, including vertical mixing, leading to biochemical alterations and affecting the surrounding ecosystem’s dynamics. In previous studies, increased nutrient concentrations and primary production were observed along the cyclone track after the storm. TC Seroja was awakened near the equator in the southeastern tropical Indian Ocean, making it interesting to investigate how the ambient ecosystem responds. Hence, we analyzed the sea surface temperature and nutrient changes during the Seroja event using multi-satellite remote sensing and numerical model data in the south of Indonesia and East Timor along the Seroja track between April 2 and 10, 2021. Immediately after the TC Seroja passed, the sea surface temperature cooled to 3 °C around the TC lane. At the same time, the spatial distribution patterns showed the upsurge of some nutrients in response to the passage of TC Seroja; the surface nitrate swells up to 1.5 mmol/m3, while phosphate increased up to 0.2 mmol/m3, and the dissolved silicate concentration enhanced up to 1.0 mmol/m3. The responses recover within 2-7 days. These results indicate that tropical cyclones contribute to nutrient enrichment in oligotrophic areas outside of their usual annual upwelling time, thereby further supporting ecosystem sustainability.

scholarly journals The Relationships of Future Anxiety with some Variables among the Vocational Training Students

2013 ◽  
Vol 7 (2) ◽  
pp. 186
Author(s):  
Zegaoua Ahmed
Keyword(s):  
Vocational Training ◽  
The Other ◽  
Average Level ◽  
Economic Dimension ◽  
Low Level ◽  
Males And Females ◽  
Relationship Of ◽  
The Relationship ◽  
Psychological Dimensions

The Purpose of this study was to investigate the level of future anxiety among students of' vocational training. The relationship of future anxiety gender and vocational specialization was tested. The researcher developed a questionnaire of future anxiety which was distributed to 112 students who were in four vocational specializations. The results revealed that there was an average level of future anxiety among the vocational training students, in the total score as well as in the vocational, academic, social, and psychological dimensions. However, there was low level of future anxiety in the economic dimension. There were also statistically significant differences between males and females on the level of future anxiety, while there were no statistically significant differences on the other dimensions attributed to the vocational specialization. In light of the findings the researcher proposed a number of recommendations. 

Precipitation anomalies in the tropical Indian Ocean and their relation to the initiation of El Niño

2002 ◽  
Vol 29 (10) ◽  
pp. 83-1-83-4 ◽  
Author(s):  
Scott Curtis ◽  
George J. Huffman ◽  
Robert F. Adler
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Tropical Indian Ocean ◽  
Precipitation Anomalies
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