scholarly journals Variability of lightning hazard over Indian region with respect to ENSO Phases

2020 ◽  
Author(s):  
Sreenath Avaronthan Veettil ◽  
Abhilash Sukumarapillai ◽  
Vijaykumar Pattathil
Keyword(s):  
Southern Oscillation ◽  
Indian Subcontinent ◽  
Monsoon Season ◽  
Northeast India ◽  
Lightning Flash ◽  
Peninsular India ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
The Impact ◽  
Enso Phases

Abstract. The El-Nino Southern Oscillation (ENSO) modulates the lightning flash rate (LFR) variability over India during pre-monsoon, monsoon, and post-monsoon seasons. The impact of ENSO phases on the LFR over the Indian subcontinent is studied using the data obtained from Optical Transient Detector and Lightning Imaging Sensors onboard the TRMM satellite. The study shows that irrespective of ENSO phases, the LFR is maximum over northeast India (NEI) in the pre-monsoon season, and the peak is shifted to the north of northwest India (NNWI) in the monsoon season. The LFR over Northeast India (NEI) and southern peninsular India (SPI) intensified (reduced) during the warm (cold) phase of ENSO in the pre-monsoon season. In the monsoon season, NEI (NNWI) is showing above normal LFR in the warm (cold) ENSO phase. It is fascinating that the three hotspots of LFR over the Indian land region became more prominent in the last decade of the monsoon season. A widespread increase of LFR is observed all over India during the warm phase of ENSO in the post-monsoon season. However, a marked increase in the LFR is confined mostly over the NNWI in the cold ENSO phase. The subtropical westerly jet stream is shifted south in association with the warm phase, and an increase in the geopotential height (GPH) is also noticed all over India in the same period. ENSO’s warm phase indirectly influences the LFR over India during the post-monsoon season by pushing the mean position of subtropical westerly towards south latitudes.

scholarly journals Variability in lightning hazard over Indian region with respect to El Niño–Southern Oscillation (ENSO) phases

2021 ◽  
Vol 21 (8) ◽  
pp. 2597-2609
Author(s):  
Avaronthan Veettil Sreenath ◽  
Sukumarapillai Abhilash ◽  
Pattathil Vijaykumar
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Indian Subcontinent ◽  
Monsoon Season ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Lightning Flash ◽  
The Impact ◽  
Enso Phases

Abstract. The El Niño–Southern Oscillation (ENSO) modulates the lightning flash density (LFD) variability over India during premonsoon, monsoon and postmonsoon seasons. This study intends to shed light on the impact of ENSO phases on the LFD over the Indian subcontinent using the data obtained from Optical Transient Detector (OTD) and Lightning Imaging Sensors (LIS) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. Results suggest the LFD over northeast India (NEI) and southern peninsular India (SPI) strengthened (weakened) during the warm (cold) phase of ENSO in the premonsoon season. During monsoon season, NNWI (north of northwest India) shows above (below) normal LFD in the cold (warm) ENSO phase. It is striking to note that there are three hot spots of LFD over the Indian land region which became more prominent during the monsoon seasons of the last decade. A widespread increase in LFD is observed all over India during the warm phase of ENSO in the postmonsoon season. A robust rise in graupel/snow concentration is found during the postmonsoon season over SPI in the ENSO warm phase, with the lowest fluctuations over the NEI and NNWI regions. The subtropical westerly jet stream is shifted south in association with the warm phase, accompanied by an increase in geopotential height (GPH) all over India for the same period. This exciting remark may explain the indirect influences of ENSO's warm phase on LFD during the postmonsoon season by pushing the mean position of the subtropical westerly towards southern latitudes. However, the marked increase in LFD is confined mostly over the NNWI in the cold ENSO phase.

scholarly journals Effect of COVID-19 Lockdown on Metal Concentration in the Water Column of Asia’s Largest Coastal Lagoon

2021 ◽  
Author(s):  
Syed Hilal Farooq ◽  
Amrit Kumar Mishra ◽  
Sandip Kumar Muhakud ◽  
Prasannajit Acharya ◽  
Pradipta Ranjan Muduli ◽  
...  
Keyword(s):  
Metal Concentration ◽  
Water Samples ◽  
Monsoon Season ◽  
Physical Parameters ◽  
Chilika Lagoon ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
The Mean ◽  
The Impact ◽  
Mean Concentration

A complete halt on all anthropogenic activities and human movement due to COVID-19 lockdown has provided a great opportunity to assess the impact of human activities on coastal marine ecosystems. The current study assessed the concentration of the metals in water samples of the largest brackish water lagoon of Asia; the Chilika lagoon in the state of Odisha, India between pre-COVID-19 and post-COVID-19 lockdown scenarios. Monthly water samples (n=30 stations) from 0.3 m depth were collected from three sectors of the lagoon seasonally; pre-monsoon, monsoon, and post-monsoon. In addition to various physical parameters [pH, salinity, alkalinity, (DO) dissolved oxygen, (TDS) total dissolved solids, and (EC) electrical conductivity] the collected water samples were analysed for 18 trace metals (Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sr, Th, Tl, U, V). Most of the physical parameters showed a significant variation between pre-and post-COVID-19 scenarios, except for pH and DO. The concentration of five metals (Be, Cd, Co, Ni, and Pb) remained below detection limits in all water samples. The impact of COVID-19 lockdown on the concentration of the metal in the water samples was noticed along with the three sectors of the lagoon. However, eight metals (Al, As, Cr, Fe, Mn, Th, U, and V) were significantly different between the COVID-19 scenarios and the remaining five metals were not statistically significant. The mean concentration of Al, As, Fe, Th, and V were higher in the pre-COVID-19 scenarios, whereas only Cr and Mn were higher in the post-COVID-19 scenarios. The mean concentration of U was similar among both COVID-19 scenarios, even though there were seasonal and sectoral differences. The seasonal influence of riverine influx was more evident on metal concentration during the monsoon season, whereas the difference between sectors was more prominent during the post-monsoon season. An increased number of correlations between physical parameters and metal concentration were observed in the post-monsoon season and post-COVID-19 scenario. This study provides evidence that the imposition of COVID-19 lockdown reduced metal influx in the water column and improved the water quality of the Chilika lagoon. Our results can be used as baseline for metal concentration in surface waters of the lagoon.

scholarly journals EI- Nino and tropical storm tracks over Bay of Bengal during post monsoon season

MAUSAM ◽  
2021 ◽  
Vol 42 (3) ◽  
pp. 257-260
Author(s):  
AKHILESH GUPTA ◽  
A. MUTHUCHAMI
Keyword(s):  
Tropical Cyclones ◽  
Bay Of Bengal ◽  
Tamil Nadu ◽  
Andhra Pradesh ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
Cent Level

The role of EI-Nino in modulating tropical cyclone motion over Bay of Bengal during post monsoon season has been examined. Storms which formed during the years 1901-1987 have been classified into recuriving or those of which crossing north of 17° N and non-recurving or those of which crossing south of 17° N the east coast of India. It has been found that in most of the cases (87 %) during EI-Nino years, the tropical cyclones which formed over Bay of Bengal crossed south of 17° N, i.e. south Andhra Pradesh Tamil Nadu coast, whereas tropical cyclones, ed during the year prior to the EI-Nino years [El- Nino (-1 ) year] are seen crossing mostly (in 79% of cases) either h of 17°N or recurving m northeastward direction. In other years this kind of behaviour is not generally onseerved. The correlation between southern oscillation indices and the fractional values of storms crossing south of 170 N for the period 1901-1987 (n=87) is found to be ---0.63 which is significant at 1 per cent level.

scholarly journals Assessment of Trophic Responses of a Reservoir to Seasonal and Annual Variations in Monsoon

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2117
Author(s):  
Su-mi Kim ◽  
Hyun-su Kim
Keyword(s):  
Water Quality ◽  
Trophic State ◽  
Monsoon Season ◽  
Phytoplankton Growth ◽  
Phosphorus Loading ◽  
Nutrient Concentrations ◽  
Trophic State Index ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
State Index

The variations in water quality parameters and trophic status of a multipurpose reservoir in response to changing intensity of monsoon rain was investigated by applying a trophic state index deviation (TSID) analysis and an empirical regression model to the data collected in two periods from 2014 to 2017. The reservoir in general maintained mesotrophic conditions, and Carlson’s trophic state index (TSIc) was affected most by TSITP. Nutrient concentrations, particularly phosphorus, did not show strong correlations with precipitation, particularly in the period with weak monsoon, and a significant increase in total phosphorus (TP) was observed in Spring 2015, indicating the possibility of internal phosphorus loading under decreased depth and stability of water body due to a lack of precipitation. TSIChl was higher than TSISD in most data in period 1 when a negligible increase in precipitation was observed in the monsoon season while a significant fraction in period 2 showed the opposite trend. Phytoplankton growth was not limited by nutrient limitation although nutrient ratios (N/P) of most samples were significantly higher than 20, indicating phosphorus-limited condition. TSID and regression analysis indicated that phytoplankton growth was limited by zooplankton grazing in the Spring, and that cell concentrations and community structure in the monsoon and post-monsoon season were controlled by the changing intensity of the monsoon, as evidenced by the positive and negative relationships between community size and cyanobacterial population with the amount of precipitation in the Summer, respectively. The possibility of contribution from internal loading and an increase in cyanobacterial population associated with weak monsoon, in addition to potential for nutrient enrichment in the post-monsoon season, implies a need for the application of more stringent water quality management in the reservoir that can handle all potential scenarios of eutrophication.

A Study on Prevalence and Seasonal Distribution of Dengue at a Tertiary Care Centre of North India

Healthline ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 100-107
Author(s):  
Arti Agrawal ◽  
Vikas Kumar ◽  
Sanjeev Kumar ◽  
Neha K Mani
Keyword(s):  
Monsoon Season ◽  
Dengue Infection ◽  
Tertiary Care ◽  
Seasonal Distribution ◽  
North India ◽  
Care Centre ◽  
Tertiary Care Centre ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
Male Preponderance

Introduction: Dengue virus infection is a major public health issue prevalent in tropical and sub-tropical countries all over the world mostly in urban and semi-urban areas. WHO estimates about 50-100 million dengue infections worldwide every year. The present study is aimed to assess the prevalence and seasonal distribution of dengue disease during three consecutive years from 2016-2018 at a tertiary care centre of North India. Method: This is an observational retrospective study conducted on total 6,481 clinical suspected cases referred from indoor and outdoor departments of Medicine and Pediatrics of one of the medical colleges of Agra during the period from 1st January 2016 to 31st December 2018. Results: The maximum positivity was recorded in the year 2016 (16.66%), followed by 2017 (14.07%) and 2018(13.56%).Our study shows male preponderance with maximum cases in the year 2018 was recorded in the month of October (22.75%) whereas the lowest in the month of May (1.96%). Most of the cases were in the age group 0-30 years with a male preponderance. The outbreak occurred during the months of August to November indicating vector transmission in the monsoon and post-monsoon season. Conclusion: From the analysis, this study reflects that the numbers of dengue cases in 2016 were maximum and outnumbered the dengue cases among three consecutive years from 2016 to 2018. The peak in dengue positivity was observed during September to October. As this disease affects the population in the monsoon and post monsoon months therefore continuous monitoring of dengue infection is important during the post-monsoon season.

scholarly journals Seasonal Nature and Trends of Tropical Cyclone Frequency and Intensity over the North Indian Ocean

2020 ◽  
Vol 15 (3) ◽  
pp. 526-534
Author(s):  
Abhisek Pal ◽  
Soumendu Chatterjee
Keyword(s):  
Time Series ◽  
Tropical Cyclone ◽  
Indian Ocean ◽  
Monsoon Season ◽  
North Indian Ocean ◽  
Post Monsoon ◽  
The North ◽  
Increasing Trend ◽  
Post Monsoon Season ◽  
Cyclone Frequency

Tropical cyclone (TC) genesis over the North Indian Ocean (NIO) region showed significant amount of both spatial and temporal variability.It was observed that the TC genesis was significantly suppressed during the monsoon (June-September) compared to pre-monsoon (March-May) and post-monsoon (October-December) season specifically in terms of severe cyclonic storms (SCS) frequency. The Bay of Bengal (BoB) was characterized by higher TC frequency but lower intensity compared to the Arabian Sea (AS). It was also observed that the TC genesis locations were shifted significantly seasonally.The movement of the TCs also portrayed some significant seasonal differences. The pre-monsoon and post-monsoon season was responsible for generating TCs with higher values of accumulated cyclone energy (ACE) compared to the monsoon. The time series of TC frequency showed a statistically significant decreasing trend whereas the time series of ACE showed astatistically significant increasing trend over the NIO.

scholarly journals Dragonflies and damselflies (Insecta: Odonata) of the Kole Wetlands, central Kerala, India

2021 ◽  
Vol 13 (3) ◽  
pp. 17963-17971
Author(s):  
A. Vivek Chandran ◽  
Subin K. Jose ◽  
Sujith V. Gopalan
Keyword(s):  
Species Richness ◽  
Monsoon Season ◽  
Survey Method ◽  
Ramsar Site ◽  
Post Monsoon ◽  
Post Monsoon Season

A year-long study was conducted at the Kole Wetlands, a Ramsar site in central Kerala to document the diversity of dragonflies and damselflies and understand their seasonality.  Checklist survey method was used to sample adult odonates in 30 randomly chosen locations.  A total of 44 species (30 dragonflies and 14 damselflies) belonging to 33 genera and eight families were recorded in the study area.  Species richness showed a peak in the post-monsoon season and a dip in the summer.  The observations support the value of the Kole Wetlands in providing valuable resources for Odonata.

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