Southwest monsoon rainfall in India: Part I-Spatial variability

Results of Principal Component Analysis (PCA) in spatial mode (S-Mode) applied on a 10 years' (1977-86) data set of weekly rainfall anomalies are presented in this study. The rainfall activity has been below average in the period under study with high standard deviations mostly over low rainfall areas. Inter - subdivisional correlation values suggest predominance of broad- scale weather systems over most parts of the country .The first principal component (PC) resemblance with the mean pattern. The second PC has been associated with active monsoon condition. The third and fourth PCs have been related to the northward progression of the Madden-Julian oscillation and the weak monsoon condition respectively. Resemblance of spatial patterns of alternative PCs with typical strong and weak monsoon activities suggest significant contributions from certain parts of the country (northeast, southeast) towards overall rainfall activity during weak monsoon situation.

Download Full-text

DAKSHIN BHARTIYA PADHAR PAR HONE WALI MONSOON WARSHA KA PRADHAN AVYAV VISHLESHAN

MAUSAM ◽

10.54302/mausam.v48i1.3939 ◽

2021 ◽

Vol 48 (1) ◽

pp. 77-82

Author(s):

O.P. SINGH

Keyword(s):

Principal Components ◽

Andhra Pradesh ◽

Monsoon Rainfall ◽

Principal Component ◽

Southwest Monsoon ◽

Northeast Monsoon ◽

Northeast Monsoon Rainfall ◽

Total Variability ◽

Southwest Monsoon Rainfall ◽

The Impact

The result of the Principal Component Analysis of southwest and northeast monsoon rainfall on the southern India plateau have been discussed. Monsoon rainfall data of five meteorological sub-divisions, i.e., Coastal Andhra Pradesh, Rayalseema, Tamilnadu, Interior parts of South Karnataka & Kerala, for a period of 33 years (1960-92), have been utilized. The results indicate that the rainfall of Coastal Andhra Pradesh and Rayalseema has maximum impact on first principal component of southwest monsoon rainfall of five meteorological sub-divisions. The study of only first principal component is sufficient in order to understand the 49% of total variability of southwest monsoon rainfall. Analysis of first three principal components is important to understand 85% of total variability of the rainfall of this season. On the first principal component of northeast monsoon rainfall of aforesaid five meteorological sub-divisions the impact of the rainfall of Kerala and south interior Karnataka has been found maximum. In order to understand the 56% of total variability the analysis of first principal component is sufficient. The special negative relation is found between northeast monsoon rainfall on the Coastal Andhra Pradesh and southwest monsoon rainfall of previous year on this very sub-division and Rayalseema. The principal components of southwest monsoon rainfall may prove useful for forecasting the northeast monsoon rainfall of southern Indian plateau.

Download Full-text

Southwest monsoon rainfall in Assam: An application of principal component analysis for understanding of variability

MAUSAM ◽

10.54302/mausam.v68i2.638 ◽

2021 ◽

Vol 68 (2) ◽

pp. 357-366

Author(s):

PIJUSH BASAK

Keyword(s):

Principal Component Analysis ◽

Principal Components ◽

Temporal Variability ◽

Monsoon Rainfall ◽

Principal Component ◽

Component Analysis ◽

Southwest Monsoon ◽

The State ◽

Spatial And Temporal Variability ◽

Southwest Monsoon Rainfall

The principal component analysis (PCA) is applied to understand the spatial and temporal variability of monsoonal rainfall in the state Assam in India. The Southwest Monsoon (SWM) rainfall data over 12 widely spread stations located over the state has been analyzed for a period of 60 years for understanding variability. A statistically significant trend and a above/below transition signal has been observed for a few stations and the corresponding principal components (PCs). Coherent regions of Northern and Southern Assam have been identified through PCA to bring out the possible significant signals. It is observed that some of PCs for state-wise and coherent regions have positive or negative trend and significant above/below transition.

Download Full-text

Variability of south west monsoon rainfall in West Bengal : An application of principal component analysis

MAUSAM ◽

10.54302/mausam.v65i4.1201 ◽

2021 ◽

Vol 65 (4) ◽

Author(s):

PIJUSH BASAK

Keyword(s):

Principal Component Analysis ◽

West Bengal ◽

Monsoon Rainfall ◽

Principal Component ◽

Component Analysis ◽

Southwest Monsoon ◽

Spatial And Temporal Variability ◽

Annual Variations ◽

South West Monsoon ◽

Southwest Monsoon Rainfall

The principal component analysis is utilized to understand the spatial and temporal variability of monsoonal rainfall. The southwest monsoon rainfall data of West Bengal, situated over 21 stations widely spread over the state, has been analyzed for a period of 60 years for inter-annual variations. A coherent subset of 8 north and 13 south stations has been studied separately to produce statistically significant inter-annual signals. It is observed that the above/below transition is quite significant both for station rainfalls and principal components for state-wise and coherent zone analysis.

Download Full-text

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

MAUSAM ◽

10.54302/mausam.v49i3.3635 ◽

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.

Download Full-text

Precipitation regionalization of southwest monsoon by hierarchical cluster analysis

MAUSAM ◽

10.54302/mausam.v60i2.1069 ◽

2021 ◽

Vol 60 (2) ◽

pp. 185-196

Author(s):

A. B. MAZUMDAR

Keyword(s):

Cluster Analysis ◽

Hierarchical Cluster Analysis ◽

Monsoon Rainfall ◽

Principal Component ◽

Hierarchical Cluster ◽

Southwest Monsoon ◽

Different Types ◽

Synoptic Features ◽

Southwest Monsoon Rainfall ◽

Homogeneous Regions

An attempt has been made to identify coherent zones of southwest monsoon rainfall over the Indian region by employing hierarchical cluster analysis. Examination of dendrograms produced by different fusion strategies revealed the presence of 13 nuclei clusters of meteorological subdivisions. Formation of these nuclei clusters could be interpreted by their average principal component (PC) scores and associated synoptic features of PCs. Higher level inter-nuclei joinings have occurred in various fusion strategies to produce different types of clusters of subdivisions. A flexible strategy providing well separated groups of meteorological sub-divisions has been found to be suitable. The method has identified six homogeneous regions of rainfall over India. The meteorological subdivisions have been found to be evenly distributed in these coherent zones. The clustering obtained by this method has been reasonable and largely interpretable.

Download Full-text

YEAST IN SOUTHWEST MONSOON RAINWATER

Fungal Territory ◽

10.36547/ft.2020.3.3.4-8 ◽

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.

Download Full-text