scholarly journals Strengthening of the Somali upwelling during the Holocene and its impact on southwest monsoon rainfall

2017 ◽  
Author(s):  
D. Balaji ◽  
Ravi Bhushan ◽  
L. S. Chamyal
Keyword(s):  
Biogenic Silica ◽  
Monsoon Rainfall ◽  
Southwest Monsoon ◽  
Last Glacial Period ◽  
The Holocene ◽  
History Of ◽  
Major Shift ◽  
Monsoon Strength ◽  
Southwest Monsoon Rainfall ◽  
The Relationship

Abstract. The history of the Somali upwelling during the last 18.5 ka has been reconstructed using biogenic silica fluxes estimated from a sediment core retrieved from the western Arabian Sea. The reconstructed record demonstrates periodic weakening and strengthening of the Somali upwelling during the past 18.5 ka. Variations in biogenic silica fluxes suggest weak upwelling during the last glacial period (18.5–15 ka BP). Strengthened upwelling during the Bølling–Allerød period (15–13 ka BP) points to post-glacial onset of the southwest monsoon. The Younger Dryas (13–11 ka BP) is again marked by reduced upwelling strength. Intensification of the Somali upwelling at the beginning of the Holocene and a decline at 8 ka BP are observed. Increases in upwelling strength recorded since 8 ka BP suggest strengthening of the southwest monsoon during the latter part of the Holocene. Linking these upwelling variations with southwest monsoon precipitation, a major shift in the relationship between the strength of the Somali upwelling and southwest monsoon rainfall from positive to negative has occurred during the pre-Holocene to the Holocene. The observed shift is attributed to the variation in the southwest monsoon strength due to the latitudinal shift of the Intertropical Convergence Zone (ITCZ) associated with changes in moisture sources.

scholarly journals Variations of the Somali upwelling since 18.5 ka BP and its relationship with southwest monsoon rainfall

2018 ◽  
Vol 14 (9) ◽  
pp. 1331-1343 ◽  
Author(s):  
Durairaj Balaji ◽  
Ravi Bhushan ◽  
Laxman Singh Chamyal
Keyword(s):  
Biogenic Silica ◽  
Southwest Monsoon ◽  
East African ◽  
Flux Variation ◽  
East African Coast ◽  
The Holocene ◽  
Precipitation Record ◽  
Latitudinal Shift ◽  
Southwest Monsoon Rainfall ◽  
The Relationship

Abstract. Somali upwelling history has been reconstructed for the last 18.5 ka BP based on biogenic silica fluxes estimated from a sediment core retrieved from the western Arabian Sea. Surface winds along the east African coast during the southwest monsoon (SWM) cause the Somali upwelling; thus, the intensity of this upwelling has been related to the variability of the SWM. Biogenic silica flux variation suggests periodic weakening and strengthening of the Somali upwelling. Weakened upwelling during the 18.5–15 ka BP period and strengthened upwelling during the Bølling–Allerød (15–12.9 ka BP) suggest the onset of the SWM. The Younger Dryas (12.9–11.7 ka BP) is marked by reduced upwelling strength, with an intensification of the Somali upwelling observed at the beginning of the Holocene and a further decline at 8 ka BP. The increase in the upwelling strength recorded since 8 ka BP suggests SWM strengthening during the latter part of the Holocene. A comparison of upwelling variations with the SWM precipitation record demonstrates a reversal in the relationship between the strength of the Somali upwelling and SWM rainfall at the beginning of the Holocene. This observed shift has been attributed to the variation in the SWM strength due to the latitudinal shift of the intertropical convergence zone (ITCZ) associated with changes in moisture sources.

scholarly journals Southwest monsoon rainfall in India : Part II - Principal components in temporal domain

MAUSAM ◽  
2021 ◽  
Vol 49 (3) ◽  
pp. 301-308
Author(s):  
A. B. MAZUMDAR
Keyword(s):  
Principal Components ◽  
Monsoon Rainfall ◽  
Principal Component ◽  
Southwest Monsoon ◽  
Temporal Domain ◽  
Synoptic Features ◽  
Southwest Monsoon Rainfall ◽  
Relationship Of ◽  
The Relationship ◽  
Low Pressure Systems

An attempt has been made towards objective identification of phases of the southwest monsoon by principal component analysis (PCA) in temporal domain (T-mode). The method utilizes the relationship of weekly rainfall activities with principal components (PCs) of southwest monsoon. Based on the relationships, subgroup of weeks with similar spatial patterns have been identified. Synoptic features of these subgroups have been brought out with the help of synoptic charts. The first four significant PCs are associated with four kinds of active phases of the southwest monsoon when the low pressure systems have typical characteristics corresponding to each PC. Thus, the study suggests a method of interpretation of PCs with the help of synoptic charts by objective identification of phases of southwest monsoon.

scholarly journals YEAST IN SOUTHWEST MONSOON RAINWATER

2020 ◽  
Vol 3 (3) ◽  
pp. 4-8
Author(s):  
SHEELA PAL
Keyword(s):  
Phase Contrast ◽  
Monsoon Rainfall ◽  
Southwest Monsoon ◽  
Yeast Cells ◽  
Successful Isolation ◽  
Tentative Model ◽  
Bacteria And Fungi ◽  
Southwest Monsoon Rainfall ◽  
Ascomycetous Yeasts ◽  
Extreme Care

Strong evidence of the presence of bacteria and fungi in the tropospheric boundary layer is available in the literature. We report successful isolation of unique morphotypes of wild ascomycetous yeasts from rainwater samples collected directly in sterile containers, taking extreme care to avoid ambient contamination. Direct and quick visualization of fresh rainwater samples under a phase contrast microscope indicated the sporadic presence of yeast cells. Further confirmation of the presence of yeast was obtained by plating of rainwater on a medium with antibiotics to generate pure colonies. We described their characteristics while molecular identification revealed it as Candida tropicalis. Yeast species  could contribute valuable knowledge about yeast transportation in the atmosphere. However, knowledge is insufficient about the yeast deposited from the atmosphere and its transportation across the atmosphere. We report and discuss these interesting and exciting results which are useful in understanding the microbiological dimension of meteorology and the southwest monsoon rainfall in the light of present discourse on global warming and climate change. We offer a tentative model for a possible source, role, and fate of the yeasts in rainwater.

scholarly journals Decreasing southwest monsoon rainfall over Myanmar in the prevailing global warming era

2019 ◽  
Vol 27 (1) ◽  
Author(s):  
G. China Satyanarayana ◽  
Venkata Bhaskar Rao Dodla ◽  
Desamsetti Srinivas
Keyword(s):  
Global Warming ◽  
Monsoon Rainfall ◽  
Southwest Monsoon ◽  
Southwest Monsoon Rainfall

scholarly journals The Effect of Tropical Cyclones on Southwest Monsoon Rainfall in the Philippines

2011 ◽  
Vol 89A ◽  
pp. 123-139 ◽  
Author(s):  
Esperanza O. CAYANAN ◽  
Tsing-Chang CHEN ◽  
Josefina C. ARGETE ◽  
Ming-Cheng YEN ◽  
Prisco D. NILO
Keyword(s):  
Tropical Cyclones ◽  
Monsoon Rainfall ◽  
Southwest Monsoon ◽  
The Philippines ◽  
Southwest Monsoon Rainfall

scholarly journals Palaeogeographical And Archaeological Records Of Natural Changes Of The Jordanowo-Niesulice Subglacial Channel Near Lubrza, The Lubusz Lakeland

2015 ◽  
Vol 34 (3) ◽  
pp. 101-116 ◽  
Author(s):  
Magdalena Ratajczak-Szczerba ◽  
Iwona Sobkowiak-Tabaka ◽  
Iwona Okuniewska-Nowaczyk
Keyword(s):  
Late Glacial ◽  
Last Glacial Period ◽  
Geochemical Composition ◽  
Palynological Analysis ◽  
The Holocene ◽  
Ams Radiocarbon Dating ◽  
History Of ◽  
Geomorphological Analysis ◽  
Geological Research ◽  
The Last Glacial

Abstract The region of the Lubusz Lakeland in western Poland where there are a lot of subglacial channels provides opportunity for multi-proxy palaeoenvironmental reconstructions. None of them has not been the object of a specific study. The developmental history of the palaeolakes and their vicinity in the subglacial trough Jordanowo-Niesulice, spanning the Late Glacial and beginning of the Holocene, was investigated using geological research, lithological and geomorphological analysis, geochemical composition, palynological and archaeological research, OSL and AMS-radiocarbon dating. Geological research shows varied morphology of subglacial channel where at least two different reservoirs functioned in the end of the Last Glacial period and at the beginning of the Holocene. Mostly during the Bølling-Allerød interval and at the beginning of the Younger Dryas there took place melting of buried ice-blocks which preserved the analysied course of the Jordanowo-Niesulice trough. The level of water, and especially depth of reservoirs underwent also changes. Palynological analysis shows very diversified course of the Allerød interval.

A climatological analysis of the southwest monsoon rainfall in the Philippines

2013 ◽  
Vol 122 ◽  
pp. 609-616 ◽  
Author(s):  
F.T. Cruz ◽  
G.T. Narisma ◽  
M.Q. Villafuerte ◽  
K.U. Cheng Chua ◽  
L.M. Olaguera
Keyword(s):  
Monsoon Rainfall ◽  
Southwest Monsoon ◽  
The Philippines ◽  
Southwest Monsoon Rainfall
Sign in / Sign up

Export Citation Format

Share Document