Comparison of the seasonal evolution of the South Asian high associated with two types of El Niño event

Abstract Altimetric observations of sea surface height anomaly (SSHA) from the TOPEX/Poseidon and ERS satellites, hydrography, and the ECMWF and Florida State University wind products are used to track warm water (≥20°C) as it is exchanged between the equatorial Pacific Ocean and the higher latitudes during 1993–2003. The large El Niño event of 1997–98 resulted in a significant discharge of warm water toward the higher latitudes within the interior of the Pacific Ocean. The exchange of anomalous warm water volume with the Northern Hemisphere appears to be blocked under the intertropical convergence zone, consistent with most current ideas on the time-mean tropical–subtropical exchange. Little of the warm water discharged northward across 5° and 8°N during the 1997–98 El Niño event could be traced as far as 10°N. To the south, however, these anomalous volumes of warm water were visible at least as far as 20°S, primarily in the longitudes around 130°–160°W. In both hemispheres most of the warm water appeared to flow westward before returning to the Tropics during the recharge phase of the El Niño–La Niña cycle. The buildup of warm water in the Tropics before the 1997–98 El Niño is shown to be fed primarily by warm water drawn from the region in the western Pacific within 5°S–15°N. The exchange cycle between the equatorial band and the higher latitudes north of the equator leads the cycle in the south by 6–8 months. These results are found in all three datasets used herein, hydrography, altimetric observations of SSHA, and Sverdrup transports calculated from multiple wind products, which demonstrates the robustness of the results.

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A Model Study of the Air–Sea Interaction Associated with the Climatological Aspects and Interannual Variability of the South Asian Summer Monsoon Development

Journal of Climate ◽

10.1175/jcli-d-11-00035.1 ◽

2012 ◽

Vol 25 (3) ◽

pp. 839-857 ◽

Cited By ~ 16

Author(s):

Ngar-Cheung Lau ◽

Mary Jo Nath

Keyword(s):

South Asian ◽

Summer Monsoon ◽

El Niño ◽

General Circulation ◽

El Nino ◽

Asian Summer Monsoon ◽

Function Analysis ◽

South Asian Summer Monsoon ◽

The South ◽

Asian Summer

Abstract The climatological characteristics and interannual variations of the development of the South Asian summer monsoon (SASM) in early summer are studied using output from a 200-yr simulation of a coupled atmosphere–ocean general circulation model (CM2.1). Some of the model results are compared with corresponding observations. Climatological charts of the model and observational data at pentadal intervals indicate that both the precipitation and SST signals exhibit a tendency to migrate northward. Enhanced monsoonal precipitation at a given site is accompanied by a reduction in incoming shortwave radiation and intensification of upward latent heat flux, and by oceanic cooling. An extended empirical orthogonal function analysis is used to identify the dates for initiation of the northward march of SASM in individual summers. It is noted that early monsoon development prevails after the mature phase of La Niña events, whereas delayed development occurs after El Niño. Sensitivity experiments based on the atmospheric component of CM2.1 indicate that the effects of SST forcings in the tropical Pacific (TPAC) and Indian Ocean (IO) on monsoon development are opposite to each other. During El Niño events, the atmospheric response to remote TPAC forcing tends to suppress or postpone monsoon development over South Asia. Conversely, the warm SST anomalies in IO, which are generated by the “atmospheric bridge” mechanism in El Niño episodes, lead to accelerated monsoon development. The net result of these two competing effects is an evolution scenario with a timing that is intermediate between the response to TPAC forcing only and the response to IO forcing only.

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Response of the South China Sea upper layer circulation to monsoon anomalies during 1997/1998 El Niño event

Aquatic Ecosystem Health & Management ◽

10.1080/14634988.2012.645750 ◽

2012 ◽

Vol 15 (1) ◽

pp. 6-13 ◽

Cited By ~ 4

Author(s):

Jian Lan ◽

Yu Wang ◽

Ying Bao

Keyword(s):

South China Sea ◽

South China ◽

El Niño ◽

El Nino ◽

The South China Sea ◽

The South ◽

China Sea ◽

El Niño Event ◽

Upper Layer Circulation

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Revisiting the relationship between the South Asian summer monsoon drought and El Niño warming pattern

Atmospheric Science Letters ◽

10.1002/asl.740 ◽

2017 ◽

Vol 18 (4) ◽

pp. 175-182 ◽

Cited By ~ 11

Author(s):

Fangxing Fan ◽

Xiao Dong ◽

Xianghui Fang ◽

Feng Xue ◽

Fei Zheng ◽

...

Keyword(s):

South Asian ◽

Summer Monsoon ◽

El Niño ◽

El Nino ◽

Asian Summer Monsoon ◽

South Asian Summer Monsoon ◽

The South ◽

Warming Pattern ◽

Asian Summer ◽

The Relationship

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Species-Specific Shifts in Diurnal Sap Velocity Dynamics and Hysteretic Behavior of Ecophysiological Variables During the 2015–2016 El Niño Event in the Amazon Forest

Frontiers in Plant Science ◽

10.3389/fpls.2019.00830 ◽

2019 ◽

Vol 10 ◽

Cited By ~ 1

Author(s):

Bruno O. Gimenez ◽

Kolby J. Jardine ◽

Niro Higuchi ◽

Robinson I. Negrón-Juárez ◽

Israel de Jesus Sampaio-Filho ◽

...

Keyword(s):

El Niño ◽

El Nino ◽

Hysteretic Behavior ◽

Amazon Forest ◽

El Niño Event ◽

Species Specific

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Declines and recovery in endangered Galapagos pinnipeds during the El Niño event

Scientific Reports ◽

10.1038/s41598-021-88350-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Diego Páez-Rosas ◽

Jorge Torres ◽

Eduardo Espinoza ◽

Adrian Marchetti ◽

Harvey Seim ◽

...

Keyword(s):

El Niño ◽

Environmental Variability ◽

El Nino ◽

Population Decline ◽

Annual Rate ◽

Population Fluctuations ◽

Galapagos Archipelago ◽

Population Decrease ◽

El Niño Event ◽

Zalophus Wollebaeki

AbstractCurrently, the Galapagos sea lion (GSL, Zalophus wollebaeki) and Galapagos fur seal (GFS, Arctocephalus galapagoensis) are among the most important endemic species for conservation in the Galapagos Archipelago. Both are classified as “Endangered” since their populations have undergone drastic declines over the last several decades. In this study we estimated the abundance of both otariids, and their population trends based using counts conducted between 2014 and 2018 in all their rookeries, and we analyzed the influence of environmental variability on pup production. The GSL population size in 2018 in the archipelago was estimated to be between 17,000 to 24,000 individuals and has increased at an average annual rate of 1% over the last five years after applying correction factors. The highest number of GSL counted in the archipelago was in 2014 followed by a population decline of 23.8% in 2015 that was associated with the El Niño event that occurred during that year. Following this event, the population increased mainly in the northern, central and southeastern rookeries. The GSL pup abundance showed a decreasing trend with the increase in intensity of the El Niño. The GFS population in 2018 was counted in 3,093 individuals and has increased at an annual rate of 3% from 2014 to 2018. A high number of GFS counted in 2014 was followed by a population decrease of 38% in 2015, mainly in the western rookeries. There was interannual population fluctuations and different growth trends among regions of the archipelago. GSL and GFS pup abundance has a strong decreasing tendency with the increase in the subthermocline temperature (ST) and the El Niño 1 + 2 index. Our results provide evidence that both species are highly vulnerable to periodic oceanographic-atmospheric events in the Galapagos Archipelago which impact prey abundance and the flow of energy in the unique Galapagos ecosystem.

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Connection between Anomalous Zonal Activities of the South Asian High and Eurasian Summer Climate Anomalies

Journal of Climate ◽

10.1175/jcli-d-15-0823.1 ◽

2016 ◽

Vol 29 (22) ◽

pp. 8249-8267 ◽

Cited By ~ 12

Author(s):

Jian Shi ◽

Weihong Qian

Keyword(s):

South Asian ◽

Surface Air Temperature ◽

Northern China ◽

Boreal Summer ◽

South Asian High ◽

The South ◽

Climate Anomalies ◽

Precipitation Anomalies ◽

Air Column ◽

Air Temperature Anomalies

Abstract Using the daily mean anomalies of atmospheric variables from the NCEP Reanalysis-1 (NCEP R1), this study reveals the connection between anomalous zonal activities of the South Asian high (SAH) and Eurasian climate anomalies in boreal summer. An analysis of variance identifies two major domains with larger geopotential height variability located in the eastern and western flanks of the SAH at around 100 and 150 hPa, respectively. For both eastern and western domains, extreme events are selected during 1981–2014 when normalized height anomalies are greater than 1.0 (less than −1.0) standard deviation for at least 10 consecutive days. Based on these events, four SAH modes that include strong and weak Tibetan modes (STM and WTM, respectively) and strong and weak Iranian modes (SIM and WIM, respectively) are defined to depict the zonal SAH features. The positive composite in the eastern (western) domain indicates the STM (SIM) manifests a robust wavelike pattern with an anomalous low at 150 hPa, and surface cold and wet anomalies over Mongolia and northern China (Kazakhstan and western Siberia) are surrounded by three anomalous highs at 150 hPa and surface warm and dry anomalies over Eurasia. Opposite distributions are also evident in the negative composites of the two domains (WTM and WIM). The surface air temperature anomalies are the downward extension of an anomalous air column aloft while the precipitation anomalies are directly associated with the height anomalies above the air column.

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