scholarly journals Characteristics of African rainfall – An update

MAUSAM ◽  
2021 ◽  
Vol 50 (2) ◽  
pp. 159-176
Author(s):  
R. P. KANE
Keyword(s):  
El Niño ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
El Nino ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
Summer Monsoon Rainfall ◽  
Sea Surface ◽  
Continental Scale ◽  
African Rainfall

Each year during 1901-1990 was characterized as having an El Nino (EN) or Southern Oscillation minimum (SO) or warm (W) or cold (C) waters in east equatorial Pacific sea surface or any combination of these, or none (non-events). In contrast to Indian summer monsoon rainfall which showed a very good association between ENSOW type years and droughts, none of the African regions showed any significant, consistent relationship with any combination, except S. Africa where a slight bias for droughts was observed during El Nino years.   When departures in specific regions were compared, often there was lack of coherence within regions. For years when departures in every region could be classified as positive or negative, all type of teleconnections between W. Africa, E. Africa and S. Africa were seen and no preponderance was observed for continental scale floods or droughts, nor for opposite depart for equator and subtropics.   Five-year running averages indicated long intervals of positive departures preceded or followed by long intervals of droughts, with average spacings of -24 years for W. Africa and E. Africa (but phases not matching) and of -17 years for S. Africa. This seems to be a basis feature of African rainfall variability.

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 The influence of El Niño–Southern Oscillation regimes on eastern African vegetation and its future implications under the RCP8.5 warming scenario

2017 ◽  
Vol 14 (18) ◽  
pp. 4355-4374 ◽  
Author(s):  
Istem Fer ◽  
Britta Tietjen ◽  
Florian Jeltsch ◽  
Christian Wolff
Keyword(s):  
Climate Change ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Rainfall Variability ◽  
Future Climate ◽  
Future Climate Change ◽  
El Nino Southern Oscillation ◽  
Vegetation Response ◽  
African Rainfall

Abstract. The El Niño–Southern Oscillation (ENSO) is the main driver of the interannual variability in eastern African rainfall, with a significant impact on vegetation and agriculture and dire consequences for food and social security. In this study, we identify and quantify the ENSO contribution to the eastern African rainfall variability to forecast future eastern African vegetation response to rainfall variability related to a predicted intensified ENSO. To differentiate the vegetation variability due to ENSO, we removed the ENSO signal from the climate data using empirical orthogonal teleconnection (EOT) analysis. Then, we simulated the ecosystem carbon and water fluxes under the historical climate without components related to ENSO teleconnections. We found ENSO-driven patterns in vegetation response and confirmed that EOT analysis can successfully produce coupled tropical Pacific sea surface temperature–eastern African rainfall teleconnection from observed datasets. We further simulated eastern African vegetation response under future climate change as it is projected by climate models and under future climate change combined with a predicted increased ENSO intensity. Our EOT analysis highlights that climate simulations are still not good at capturing rainfall variability due to ENSO, and as we show here the future vegetation would be different from what is simulated under these climate model outputs lacking accurate ENSO contribution. We simulated considerable differences in eastern African vegetation growth under the influence of an intensified ENSO regime which will bring further environmental stress to a region with a reduced capacity to adapt effects of global climate change and food security.

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.

Multiscale Variability of the River Runoff System in China and Its Long-Term Link to Precipitation and Sea Surface Temperature

2005 ◽  
Vol 6 (4) ◽  
pp. 550-570 ◽  
Author(s):  
Yongkang Xue ◽  
Jinjun Ji ◽  
Shufen Sun ◽  
Guoxiong Wu ◽  
K-M. Lau ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
River Runoff ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Sea Surface ◽  
Delayed Response ◽  
Continental Scale ◽  
Runoff Depth

Abstract This is an exploratory study to investigate the spatial and temporal characteristics of east China’s (EC) river runoff and their relationship with precipitation and sea surface temperature (SST) at the continental scale. Monthly mean data from 72 runoff stations and 160 precipitation stations in EC, covering a period between 1951 and 1983, are used for this study. The station river runoff data have been spatially interpolated onto 1° grid boxes as runoff depth based on an extracted drainage network. Comparing runoff depth with precipitation shows that seasonal variation in runoff is consistent with the development of the summer monsoon, including the delayed response of runoff in several subregions. The dominant spatial scales and temporal patterns of summer runoff and precipitation are studied with empirical orthogonal function (EOF) analysis and wavelet analyses. The analyses show interannual, biennial, and longer-term variations in the EOF modes. South–north dipole anomaly patterns for the first two runoff EOF’s spatial distributions have been identified. The first/second runoff principal components (PCs) are highly correlated with the second/first precipitation PCs, respectively. The summer runoff’s EOF PCs also show significant correlations with the multivariate El Niño–Southern Oscillation index (MEI) of the summer and winter months, while the summer precipitation PCs do not. Statistic analysis shows that EOF1 of runoff and EOF2 of precipitation are related to El Niño, while EOF2 of runoff and EOF1 of precipitation are related to a dipole SST anomaly over the northwestern Pacific. The interdecadal relationship between summer runoff, precipitation, and SST variability is further studied by singular value decomposition (SVD) analysis. Pronounced warming (SST) and drying (runoff) trends in first SVD PCs have been identified. These SVDs are used to reconstruct a decadal anomaly pattern, which produces flooding in part of the Chang Jiang River basin and dryness in the northern EC, consistent with observations.

scholarly journals THE INDIAN SUMMER MONSOON CONTRIBUTION TO THE JJA RAINFALL OVER THE NOTERN PART OF SUMATRA DURING THE CO-OCCURING EL NINO AND DIPOLE MODE (+) YEARS

2010 ◽  
Vol 4 (1) ◽  
Author(s):  
Sri Woro B.Harijono
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
El Niño ◽  
Wavelet Transformation ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
El Nino ◽  
Summer Monsoon Rainfall ◽  
Dipole Mode ◽  
Time Frequency

This article describes the further study investigating the JJA rainfall formation in the northern part of Sumatra during the co-occuring El Nino and Dipole Mode (+) years. Analyses based on wavelet transformation reveal that the rainfall in that part of Sumatra is insensitive or at least insignificantly influenced by El Nino and or DM. This study confirms also that the Indian Summer Monsoon (IM) may play important roles in the rainfall budget of the region including in compensating the possible reduction effects of both El Nino and DM on the JJA rainfall. The characteristics of JJA rainfall over the northern part of Sumatra on a wavelet time-frequency plane are descreibed, and the relative contributions of EN-DM-Indian summer monsoon in the rainfall over the nothern part of Sumatra are demonstrated by using multicoliner statistical analysis. Keywords: Indian Summer Monsoon, Rainfall, El Nino, Dipole Mode.

scholarly journals Timing of El Niño–Related Warming and Indian Summer Monsoon Rainfall

2008 ◽  
Vol 21 (11) ◽  
pp. 2711-2719 ◽  
Author(s):  
Chie Ihara ◽  
Yochanan Kushnir ◽  
Mark A. Cane ◽  
Alexey Kaplan
Keyword(s):  
Summer Monsoon ◽  
El Niño ◽  
Monsoon Rainfall ◽  
El Nino ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Summer Monsoon Rainfall ◽  
Equatorial Pacific ◽  
Central Pacific ◽  
Eastern Equatorial Pacific

Abstract The relationship between all-India summer monsoon rainfall (ISMR) and the timing of (El Niño–Southern Oscillation) ENSO-related warming/cooling is investigated, using observational data during the period from 1881 to 1998. The analysis of the evolutions of Indo-Pacific sea surface temperature (SST) anomalies suggests that when ISMR is not below normal despite the co-occurrence of an El Niño event, warming over the eastern equatorial Pacific starts from boreal winter and evolves early so that the western-central Pacific and Indian Ocean are warmer than normal during the summer monsoon season. In contrast, when the more usual El Niño–dry ISMR relationship holds, the eastern equatorial Pacific starts warming rapidly only about a season before the reference summer so that the western-central Pacific and Indian Oceans remain cold during the monsoon season.

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