Variability of summer monsoon rainfall over Indo-Gangetic plains in relation to El-Nino/La-Nina

2015 ◽  
Vol 78 (2) ◽  
pp. 837-853 ◽  
Author(s):  
R. Bhatla ◽  
Madhu Singh ◽  
R. K. Mall ◽  
A. Tripathi ◽  
P. V. S. Raju
Keyword(s):  
Summer Monsoon ◽  
El Niño ◽  
Monsoon Rainfall ◽  
El Nino ◽  
Summer Monsoon Rainfall ◽  
La Niña ◽  
Gangetic Plains ◽  
La Nina

scholarly journals El Nino of 1997-1998 and Indian Monsoon

MAUSAM ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 57-66
Author(s):  
G. C. ASNANI
Keyword(s):  
Sea Level ◽  
Summer Monsoon ◽  
El Niño ◽  
Monsoon Rainfall ◽  
El Nino ◽  
India Meteorological Department ◽  
Summer Monsoon Rainfall ◽  
La Niña ◽  
Sea Level Pressure ◽  
La Nina

El-Nino of 1997-1998 was accompanied by severe global weather anomalies, which generated widespread interest at all levels in the world. As a result, United Nations General Assembly passed a resolution (52 / 200) urging International co-operation to reduce the adverse impact of El-Nino on human society and Environment. The El-Nino (Warm Phase) commenced around April – May 1997, reached peak intensity around December 1997 and ended around May 1998. La-Nina (Cold Phase) started around this time, reached its peak in January 1999, weakened around June - July 1999 and has continued in its weak phase at the time of writing, August 1999.   Development and decay of the El-Nino are illustrated through SST,SOI and sea-water temperature below the sea-surface. Features during peak period of El-Nino are illustrated through SST, sea-level pressure, surface wind, OLR, and Walker Circulation. There is clear evidence of west-to-east propagation of OLR anomaly, 850 hPa zonal wind anomaly and sea-level pressure anomaly. SST anomaly pattern did not give strong evidence of this type of zonal progression.   El-Nino is global in nature.   El-Nino / La-Nina years during the 120-year period 1871-1990 are tabulated along with All India Summer Monsoon Rainfall (AISMR) anomalies. There is evidence of El-Nino years tending to become years of deficit rainfall and La-Nina years being years of excess rainfall over India. El-Nino / La-Nina events, which can be predicted 6-12 months in advance, can be used and are being used as part of the prediction formulae, in the issue of official monsoon rainfall forecast by India Meteorological Department. Based on El-Nino considerations alone, it has been feared, in some quarters, that 1997 might become a year of extreme deficit summer monsoon rainfall. However, the actual rainfall over India during June – September 1997 was 2 % above normal. India Meteorological Department had predicted "normal" rainfall (+-10% of the rainfall).

scholarly journals Influence of Asian Summer Monsoon Anticyclone on the Trace gases and Aerosols over Indian region

2019 ◽  
Author(s):  
Ghouse Basha ◽  
M. Venkat Ratnam ◽  
Pangaluru Kishore ◽  
S. Ravindrababu ◽  
Isabella Velicogna
Keyword(s):  
Summer Monsoon ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Asian Summer Monsoon ◽  
Monsoon Season ◽  
Trace Gases ◽  
La Niña ◽  
La Nina ◽  
Asian Summer

Abstract. The Asian Summer Monsoon Anticyclone (ASMA) persisting during monsoon season in the upper troposphere and lower stratosphere (UTLS) region play an important role in confining the trace gases and aerosols for a longer period thus affects regional and global climate. Our understanding on these trace gases and aerosols variability in the ASMA is limited. In this study, the effect of the ASMA on the trace gases (Water Vapour (WV), Ozone (O3), Carbon Monoxide (CO)) and aerosols (Attenuated Scattering Ratio (ASR)) obtained from long-term (2006–2016) satellite measurements is investigated. Since the ASMA is present in the UTLS region, its influence on the tropopause characteristics is also explored. Higher tropopause altitude, WV, CO and ASR confining to the ASMA region is observed, whereas tropopause temperatures and O3 are found low. There exists large inter-annual variation in the ASMA and hence its effect on these trace gases and aerosols are also seen clearly. A significant relationship is also observed between the phases of Quasi-Biannual Oscillation (QBO) and El Niño Southern Oscillation (ENSO) on the trace gases and ASR, including the tropopause when measurements in the ASMA region are subject to multivariate regression analysis. Further, the influence of the Indian summer monsoon (ISM) activity on the ASMA trace gases and aerosols is studied with respect to active and break spells of monsoon, strong and weak monsoon years, strong La Niña, El Niño years. Results show a significant increase in WV, CO and decrease in O3 during the active phase of the ISM, strong monsoon years and strong La Niña years in the ASMA. Enhancement in the ASR values during the strong monsoon years and strong La Niña years is observed. Thus, it is prudent to conclude that the dynamics of the ASMA play an important role in the confinement of several trace gases and aerosols and suggested to consider the activity of summer monsoon while dealing with them at sub-seasonal scales.

Indian summer monsoon rainfall variability in response to differences in the decay phase of El Niño

2016 ◽  
Vol 48 (7-8) ◽  
pp. 2707-2727 ◽  
Author(s):  
Jasti S. Chowdary ◽  
H. S. Harsha ◽  
C. Gnanaseelan ◽  
G. Srinivas ◽  
Anant Parekh ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
El Niño ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
El Nino ◽  
Rainfall Variability ◽  
Summer Monsoon Rainfall ◽  
Decay Phase

scholarly journals El Nino, Southern Oscillation, equatorial eastern Pacific sea surface temperatures and summer monsoon rainfall in India

MAUSAM ◽  
2021 ◽  
Vol 49 (1) ◽  
pp. 103-114
Author(s):  
R. P. KANE
Keyword(s):  
Summer Monsoon ◽  
El Niño ◽  
Monsoon Rainfall ◽  
El Nino ◽  
Southern Oscillation ◽  
Summer Monsoon Rainfall ◽  
Stratospheric Wind ◽  
India Summer Monsoon ◽  
Cold Events ◽  
India Summer Monsoon Rainfall

For the 120 yean (1871-1990), every year was designated as an El Nino (EN), or Southern Oscillation (SO), minimum or a combination of these, or none. For all India summer monsoon rainfall (ISMR), unambiguous ENSOW [SO and W (warm events) in the middle of the calendar year] seemed to be best associated with droughts and events of type C (cold events) were best associated with floods. However, some droughts occurred without the presence of EN related events and some floods occurred even in the presence of EN related events. In these cases, other parameters such as Eurasian snow cover or stratospheric wind QBO might have had a larger influence.

scholarly journals Characteristics of the Onset, Withdrawal, and Breaks of the Western North Pacific Summer Monsoon in the 1949–2014 Period

2020 ◽  
Vol 33 (17) ◽  
pp. 7371-7389
Author(s):  
Inmaculada Vega ◽  
Pedro Ribera ◽  
David Gallego
Keyword(s):  
Interannual Variability ◽  
Summer Monsoon ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
La Niña ◽  
Onset Date ◽  
Central Pacific ◽  
La Nina

ABSTRACTThe western North Pacific summer monsoon (WNPSM) onset and withdrawal dates as well as its breaks have been determined throughout the 1949–2014 period by defining the monsoon daily directional index (MDDI). This index, developed exclusively with wind direction observations, is an upgrade of the monthly western North Pacific directional index. The onset date shows a high interannual variability, varying between early May and early August, whereas the WNPSM withdrawal shows a lower interannual variability, occurring between October and mid-November. The MDDI reflects the multibreak character of the WNPSM. Breaks, which tend to last a few weeks, are more likely to happen from mid-August to early September and from late June to mid-July. This bimodal distribution shows decadal variability. In addition, the monsoon dates determined by the MDDI show very good agreement with relationships previously described in literature, such as the influence of tropical Pacific SST on the monsoon onset/withdrawal and changes in tropical cyclone (TC) tracks related to monsoon breaks. The WNPSM tends to start earlier (later) and finish later (earlier) under eastern Pacific (EP) La Niña (El Niño) conditions, especially from the 1980s on. Central Pacific (CP) ENSO is also associated with the monsoon withdrawal, which is advanced (delayed) under CP El Niño (La Niña). TCs tend to move from the Philippine Sea to the South China Sea during active monsoon days whereas they tend to reach higher latitudes during inactive monsoon days, especially in August and July.

scholarly journals Asymmetric response of the Indian summer monsoon to positive and negative phases of major tropical climate patterns

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arindam Chakraborty ◽  
Priyanshi Singhai
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
El Niño ◽  
El Nino ◽  
Tropical Climate ◽  
La Niña ◽  
Moisture Convergence ◽  
La Nina ◽  
Climate Patterns ◽  
Tropical Teleconnections

AbstractThe existing theories for the tropical teleconnections to Indian summer monsoon (ISM) are diverse in approaches. As a result, it is impossible to quantify the relative impacts of different tropical climate patterns on ISM, complying with a single physical mechanism. Here, we show that tropical teleconnections to ISM can be explained through net moisture convergence driven by surface pressure (Ps) gradients surrounding the Indian region. The positive and negative phases of major tropical climate patterns modulate these pressure gradients asymmetrically in the zonal and/or meridional directions leading to asymmetric changes in moisture convergence and ISM rainfall (ISMR). Stronger El Nino droughts than La Nina floods are due to greater decreased eastward moisture flux over the Arabian Sea during El Nino than the corresponding increase during La Nina driven by proportionate meridional Ps gradients. While the equatorial Atlantic Ocean’s sea surface temperature in boreal summer and El Nino Southern Oscillation in the preceding winter changes ISMR significantly, moisture convergence anomalies driven by the Indian Ocean Dipole were insignificant. Moreover, while ISMR extremes during ENSO are due to asymmetric changes in zonal and meridional gradients in Ps, non-ENSO ISMR extremes arise due to the zonal gradient in zonally symmetric Ps anomalies.

scholarly journals The Zonal Oscillation and the Driving Mechanisms of the Extreme Western North Pacific Subtropical High and Its Impacts on East Asian Summer Precipitation

2019 ◽  
Vol 32 (10) ◽  
pp. 3025-3050 ◽  
Author(s):  
Tat Fan Cheng ◽  
Mengqian Lu ◽  
Lun Dai
Keyword(s):  
Summer Monsoon ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
La Niña ◽  
Positive Phase ◽  
La Nina ◽  
Asian Summer ◽  
Zonal Oscillation

Abstract This paper scrutinizes the zonal oscillation of the western North Pacific subtropical high (WNPSH) via diagnosing its two extreme phases, which are defined by the top 10% strongest (positive phase) and the weakest (negative phase) WNPSH index (WNPSHI) days during summers in 1979–2016. Key findings include the following: a tripole pattern consisting of intensified (weakened) precipitation over the Maritime Continent and the East Asian summer monsoon regions, and suppressed (strengthened) precipitation over the western North Pacific summer monsoon region during positive (negative) WNPSH phases; a westward movement of WNPSH-induced precipitation anomalies that subsequently affects eastern China, Japan, and the Korean Peninsula at different time lags; an OLR–vorticity pattern explained by atmospheric responses to thermal sources is suggested to drive the oscillation; and the competitive interaction of local air–sea feedbacks, especially during the positive phase. In addition, moderate-to-strong positive correlations between the WNPSHI and the Niño-3.4 index are found on 1–2-, 2–3-, and 3–6-yr time scales; both exhibit decadal shifts to a higher-frequency mode, suggesting the intensification of both the zonal WNPSH oscillation and the ENSO under the changing climate and their close interdecadal association. A nonlinear quasi-biennial WNPSH–ENSO relationship is identified: the positive (negative) WNPSH phase sometimes occurs during 1) a decaying El Niño (La Niña) in the preceding summer/autumn, and/or 2) a developing La Niña (El Niño) in the current summer/autumn. A full ENSO transition from moderate-to-strong El Niño to La Niña is often seen during the positive phase, offering potential in predicting ENSO events and extreme WNPSH phases and thereby the summer monsoon rainfall in East Asia.

Sign in / Sign up

Export Citation Format

Share Document