Spectra of seismic noise at selected Indian stations

India Meteorological Department (IMD) is operating five digital seismograph systems at New Delhi (NDI),.Shillong (SHL), Pune (POO), Kodaikanal (KDK) and Dhamlsala (DHM) since last few years. The details pertaining to instrumental characteristics and software for data retrieval and processing are presented in this paper, Through PC based algorithms. noise pectra are computed and interpreted for these five stations. It is found that the maximum peak occurs at about 6Hz for Pune. Shillong and Kodaikanal while at New Delhi and Dharmsala, it is noted at about 2 Hz. The spectral peak at Shillong as deduced from the SRO system shifts to about I Hz which is in agreement with a similar observation reported at Gauribidanur seismic array.

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Some aspects of squall over Indira Gandhi International airport, New Delhi

MAUSAM ◽

10.54302/mausam.v63i4.419 ◽

2021 ◽

Vol 63 (4) ◽

pp. 623-638

Author(s):

SURESH RAM ◽

M. MOHAPATRA

Keyword(s):

Meteorological Parameters ◽

Environmental Changes ◽

Lower Troposphere ◽

India Meteorological Department ◽

Dew Point ◽

New Delhi ◽

Dry Air ◽

Intensity Duration Frequency ◽

Level Inversion ◽

Period Of Occurrence

A study is undertaken to analyse the characteristics of squall over Delhi and to find out the potential precursors for its prediction. For this purpose, the squall data of Indira Gandhi International (IGI) airport along with the surface and upper air meteorological parameters recorded by India Meteorological Department have been considered for all individual months over the period of 2001-2010. Apart from the characteristics like period of occurrence, intensity, duration, frequency and nature of squall, the environmental changes due to squall and thermodynamic features and indices leading to squall have been analysed. Higher than normal warming of lower troposphere upto 700 hPa level in March, April & June and at 925 hPa in May accompanied with cold dry air advection leading to lower than normal dew point in middle and upper levels (500-300 hPa in March, May and June, 400-300 hPa in April) are favourable for occurrence of the squall over Delhi. The lower level inversion in March and April only also helps in the occurrence of squall. In monsoon months of July- September, cold and dry air advection in middle and upper tropospheric levels (8- 15° C below normal dew point at 400-300 hPa in July, about 15° C below normal dew point at 300-200 hPa in August and 17- 24° C below normal dew point at 500-300 hPa in September) favours occurrence of squall over Delhi. Unlike pre-monsoon months lower level moisture does not play any role for the occurrence of squall over Delhi in monsoon months. Significantly higher than normal SWEAT index in March to September at 0000 UTC can be used as predictor of squall over Delhi on that day. Total totals index is the next suitable precursor for all the months except June.

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GFZ Wireless Seismic Array (GFZ-WISE), a Wireless Mesh Network of Seismic Sensors: New Perspectives for Seismic Noise Array Investigations and Site Monitoring

Sensors ◽

10.3390/s100403280 ◽

2010 ◽

Vol 10 (4) ◽

pp. 3280-3304 ◽

Cited By ~ 25

Author(s):

Matteo Picozzi ◽

Claus Milkereit ◽

Stefano Parolai ◽

Karl-Heinz Jaeckel ◽

Ingo Veit ◽

...

Keyword(s):

Seismic Noise ◽

Wireless Mesh Network ◽

Seismic Array ◽

Mesh Network ◽

Wireless Mesh ◽

Site Monitoring ◽

Seismic Sensors

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Dominant seismic noise sources in the Southern Ocean and West Pacific, 2000-2012, recorded at the Warramunga Seismic Array, Australia

Geophysical Research Letters ◽

10.1002/2014gl060073 ◽

2014 ◽

Vol 41 (10) ◽

pp. 3455-3463 ◽

Cited By ~ 27

Author(s):

Anya M. Reading ◽

Keith D. Koper ◽

Martin Gal ◽

Leon S. Graham ◽

Hrvoje Tkalčić ◽

...

Keyword(s):

Southern Ocean ◽

Seismic Noise ◽

Seismic Array ◽

Noise Sources ◽

West Pacific

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Impact Assessment of Block Level Agro Advisories for Saving Input Cost of Farmers under Old Gangetic Plains of West Bengal - A Case Study in Malda

Current Journal of Applied Science and Technology ◽

10.9734/cjast/2020/v39i2030812 ◽

2020 ◽

pp. 86-96

Author(s):

Debjyoti Majumder ◽

Rakesh Roy ◽

F. H. Rahman ◽

B. C. Rudra

Keyword(s):

West Bengal ◽

Monsoon Season ◽

India Meteorological Department ◽

Weather Forecast ◽

Economic Benefits ◽

Weather Data ◽

New Delhi ◽

Medium Range Weather Forecast ◽

Net Returns ◽

Block Level

Biweekly block level Agromet bulletins were disseminated based on medium range weather forecast with an objective to assess the effectiveness and usefulness of Block level Agro Advisory Services (AAS) and quantify the economic benefits through adopting the micro scale agromet advisory in their day to day agricultural operations at Malda, West Bengal. Two farmers groups were considered for the study on the basis of adoption and non-adoption of the agro-met advisories. Crop situation of these farmers were compared with nearby fields having the same crops where forecast were not adopted among non AAS farmers. The entire cost incurred along with yield and net returns were calculated from sowing to marketing of goods. Similarly, the weather forecast and actual weather data received from India Meteorological Department, New Delhi were compared to verify the accuracy of rainfall forecast for the year 2019-20 at GKMS centre, Malda KVK, West Bengal. It was apparent that the value of ratio score was higher during winter (84%) than pre-monsoon (80%), post-monsoon (79%) and monsoon (74%). However, the value of threat score was also found maximum during pre-monsoon season (79%). Statistical analysis like correlation coefficient, RMSE values of wind direction were found too high in all the four seasons to accept any homogeneity in the predicted and observed values. Blockwise verification of rainfall over the year showed the range of accuracy forecast for rainfall in between 67–76%. This forecast directly had a significant role in profit generation among the AAS adaptive farmers whose additional profit enhancement for maize cultivation was between 12% and 19% only towards cost of irrigation as compared to non-adaptive farmers. The study also showcased that the AAS adaptive farmers had a better livelihood as compared to non-AAS adaptive farmers.

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Some autoregressive models for short-period seismic noise

Bulletin of the Seismological Society of America ◽

10.1785/bssa0650030677 ◽

1975 ◽

Vol 65 (3) ◽

pp. 677-691

Author(s):

D. Tjøstheim

Keyword(s):

Seismic Noise ◽

Parametric Model ◽

Seismic Array ◽

Autoregressive Models ◽

Residual Variance ◽

Time Varying ◽

Third Order ◽

Short Period ◽

Time Variations ◽

Using Data

abstract It is shown that short-period seismic noise at the NORSAR seismic array can be described by a parametric model having the form X ( t ) − a 1 ( t ) X ( t − 1 ) − … − a p ( t ) X ( t − p ) = Z ( t ) where X(t) is used to denote the noise process. This is a nonstationary generalization of the standard autoregressive models allowing time-varying autoregressive coefficients and a nonstationary white-noise residual process Z(t). The coefficients a1(t), a2(t), …ap(t) and the residual variance σ2z(t) are estimated using data from the NORSAR seismic array. It is found that the short-period noise at NORSAR is quite satisfactorily described by a third-order (p = 3) model. Also, it is found that the nonstationary character of the noise is due primarily to time variations of the residual variance and the lower order autoregressive coefficients.

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Sources of primary and secondary microseisms

Bulletin of the Seismological Society of America ◽

10.1785/bssa0840010142 ◽

1994 ◽

Vol 84 (1) ◽

pp. 142-148

Author(s):

Robert K. Cessaro

Keyword(s):

Seismic Noise ◽

Low Frequency ◽

Seismic Array ◽

Wave Number ◽

Ocean Bottom ◽

Wide Angle ◽

Frequency Wave ◽

Long Period ◽

Seismic Records ◽

Near Shore

Abstract Low-frequency (0.01 to 0.2 Hz) seismic noise, arising from pelagic storms, is commonly observed as microseisms in seismic records from land and ocean bottom detectors. One principal research objective, in the study of microseisms, has been to locate their sources. This article reports on an analysis of primary and secondary microseisms (i.e., near and double the frequency of ocean swell) recorded simultaneously on three land-based long-period arrays (Alaskan Long Period Array, Montana Large Aperture Seismic Array, and Norwegian Seismic Array) during the early 1970s. Reliable microseism source locations are determined by wide-angle triangulation, using the azimuths of approach obtained from frequency-wave number analysis of the records of microseisms propagating across these arrays. Two near-shore sources of both primary and secondary microseisms appear to be persistent in the sense that they are associated with essentially constant near-shore locations. Secondary microseisms are observed to emanate from wide-ranging pelagic locations in addition to the same near-shore locations determined for the primary microseisms.

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Monsoons of the world. New Delhi (India Meteorological Department), 1960. Pp. x, 270, Figures; Tables. 12.00 Rupees

Quarterly Journal of the Royal Meteorological Society ◽

10.1002/qj.49708737324 ◽

1961 ◽

Vol 87 (373) ◽

pp. 460-460

Keyword(s):

India Meteorological Department ◽

New Delhi ◽

The World

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District level value-added dynamical-synoptic forecast system for rainfall

MAUSAM ◽

10.54302/mausam.v57i2.468 ◽

2021 ◽

Vol 57 (2) ◽

pp. 209-220

Author(s):

B. LAL ◽

O. P. SINGH ◽

ONKARI PRASAD ◽

S. K. ROY BHOWMIK ◽

S. R. KALSI ◽

...

Keyword(s):

Weather Forecasting ◽

Value Added ◽

India Meteorological Department ◽

Southwest Monsoon ◽

District Level ◽

New Delhi ◽

Weather Forecasts ◽

Synoptic Weather ◽

Mm5 Model ◽

Medium Range

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