Delhi, India
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Mandal H.S.,Mausam Bhawan | Shukla A.K.,Mausam Bhawan | Khan P.K.,Indian School of Mines | Mishra O.P.,Geological Survey of India
Pure and Applied Geophysics | Year: 2013

The Son-Narmada-Tapti lineament and its surroundings of Central India (CI) is the second most important tectonic regime following the converging margin along Himalayas-Myanmar-Andaman of the Indian sub-continent, which attracted several geoscientists to assess its seismic hazard potential. Our study area, a part of CI, is bounded between latitudes 18°-26°N and longitudes 73°-83°E, representing a stable part of Peninsular India. Past damaging moderate magnitude earthquakes as well as continuing microseismicity in the area provided enough data for seismological study. Our estimates based on regional Gutenberg-Richter relationship showed lower b values (i.e., between 0.68 and 0.76) from the average for the study area. The Probabilistic Seismic Hazard Analysis carried out over the area with a radius of ~300 km encircling Bhopal yielded a conspicuous relationship between earthquake return period (T) and peak ground acceleration (PGA). Analyses of T and PGA shows that PGA value at bedrock varies from 0.08 to 0.15 g for 10 % (T = 475 years) and 2 % (T = 2,475 years) probabilities exceeding 50 years, respectively. We establish the empirical relationships (Formula Presented.) and (Formula Presented.) between zero period acceleration (ZPA) and shear wave velocity up to a depth of 30 m [Vs (30)] for the two different return periods. These demonstrate that the ZPA values decrease with increasing shear wave velocity, suggesting a diagnostic indicator for designing the structures at a specific site of interest. The predictive designed response spectra generated at a site for periods up to 4.0 s at 10 and 2 % probability of exceedance of ground motion for 50 years can be used for designing duration dependent structures of variable vertical dimension. We infer that this concept of assimilating uniform hazard response spectra and predictive design at 10 and 2 % probability of exceedance in 50 years at 5 % damping at bedrocks of different categories may offer potential inputs for designing earthquake resistant structures of variable dimensions for the CI region under the National Earthquake Hazard Reduction Program for India. © 2013 The Author(s).

Pradhan D.,Building Radar | Mitra A.,Mausam Bhawan | De U.K.,Jadavpur University
Indian Journal of Radio and Space Physics | Year: 2012

A study of five tropical cyclones in the Bay of Bengal has been conducted to estimate the pressure drop in the eye of the cyclone and associated storm surge height using Doppler velocity data. A new value of constant K (13.637) has been found in the empirical relation Vmax = K(P-Pc) between maximum velocity (Vmax) and central pressure drop (P-Pc) in terms of maximum radial velocity measured by the Doppler Weather Radar (DWR) for coastal region of India. The present study provides an alternate method for estimating central pressure drop and expected storm surge height associated to a tropical cyclone. The study also reveals that the storm surge height estimated from Doppler velocity measurements for these cyclones is very close to the actual occurrence. The results of pressure drop estimates from Doppler velocity are in close agreement with the satellite estimates. It is also observed that DWR estimates are sometimes better than those from satellite. However, the limitation of DWR is the limited range of observation (400 km) and shorter duration of cyclone tracking.

Das A.K.,Mausam Bhawan | Bhowmick M.,University of Leeds | Kundu P.K.,Jadavpur University | Roy Bhowmik S.K.,Mausam Bhawan
Geofizika | Year: 2014

The WRF model forecast during monsoon season 2010 has been verified with daily observed gridded rainfall analysis with 0.5° spatial resolution. Firstly, the conventional neighborhood technique has been deployed to calculate common scores like mean error and root mean square error. Along with, widely used two categorical skill scores have been computed for seven different rainfall thresholds. The scores only found the general nature of the model performance and depicted the degradation of forecast accuracy exceeding moderate rainfall category of 7.5 mm. The object oriented Contiguous Rain Area method also has been considered for the verification of rainfall forecasts to gather more information about model performance. The method similarly has endorsed that the performance of the model degrades along with the increase in rainfall amount. But at the same time, the decomposition of mean square error has pointed out that the maximum error occurred due the shifting of rain object or event in the forecast compared to observation. The volume error contributes less as compared to pattern error in 24 hour forecasts irrespective of rainfall thresholds. But in 48 hour forecasts, their values are comparable and change along with rainfall threshold. During whole monsoon season, all contiguous rain areas in model forecasts have been searched over observed rainfall analyses applying best-fit criteria. For contiguous rain areas below 50 mm more than 70 percent match was found. © 2014, Geofizicki Zavod. All rights reserved.

Dutta D.,Kohima Science College | Sharma S.,Kohima Science College | Kannan B.A.M.,Mausam Bhawan | Venketswarlu S.,Mausam Bhawan | And 3 more authors.
Indian Journal of Radio and Space Physics | Year: 2012

A study is carried out to investigate the sensitivity of Z-R relations and spatial variability of error in a Doppler Weather Radar (DWR) measured rain intensity. For this purpose, observations from a DWR at Satish Dhawan Space Centre, SHAR(13.66°N, 80.23°E) and five units of automatic tipping bucket rain gauges around the DWR are utilized. It is found that rain with intensity > 20 mm h-1 occurs for 16% of the total rain time but its contribution is 53% to the total rainfall. Sensitivity of Z-R relations are examined with the help of Z-R relations developed by two different approaches. One set of relations are developed from Joss Waldvogel Disdrometer (JWD) observations of rain drop size distribution (ZJWD-RJWD) and other set of relations are developed with the help of combined use of DWR and rain gauge observations (ZDWR-RRG). Performance of the DWR is improved with (ZDWR-RRG) relation. Using ZDWR-RRG relations for Z ≤ 30 dBZ and Z > 30 dBZ, the root mean square error (rmse) and bias for DWR measured rain intensity is reduced by 28% & 39% and 33% & 74%, respectively. The bias and error between DWR and rain gauge measured rain intensity are found to decrease with respect to decrease in distance between the rain gauges and DWR.

Panwar V.,National Physical Laboratory India | Panwar V.,University of Delhi | Jain A.R.,National Physical Laboratory India | Goel A.,University of Delhi | And 3 more authors.
Atmospheric Research | Year: 2012

Spatial and temporal variation of water vapor mixing ratio (WVMR) is examined for its association with the convective activity in upper troposphere and lower stratosphere over tropical region particularly Asian monsoon region (AMR) and Indonesian-Australian West Pacific region (IAWPR) using WVMR obtained from MLS satellite with simultaneous daily mean OLR from NOAA and daily mean wind from NCEP reanalysis. An examination of WVMR at various pressure levels during high water vapor regime (moist Phase) indicates that water vapor (WV) transport, in troposphere, is rather fast up to a level of ~. 147. hPa. Seasonal variation of WVMR over tropical lower stratosphere (TLS) is noted to be closely associated with seasonal northward movement of intertropical convergence zone (ITCZ). Convection activity over AMR appears to be a prominent contributor to the moist phase of WVMR seasonal cycle in TLS. However, other tropical regions may also be contributing to the seasonal variability of WVMR. Low WV (dry) phase of the WVMR seasonal cycle in TLS observed during NH winter and early spring months may be caused by the appearance of extreme cold temperatures (≤ 191. K) close to tropopause heights over IAWPR. Mechanisms that could cause such low temperatures over IAWPR are discussed. Intraseasonal oscillations with period of 30-40. days are observed in WVMR at various pressure levels. At 100. hPa level such oscillations are noted to be closely associated with similar oscillation in OLR and temperature. These observations suggest that variations in OLR (proxy of convection activity) produce such oscillation in WVMR. Present analysis thus report signature of convection in upward transport of WV, seasonal and intraseasonal oscillation in WVMR in upper troposphere and lower stratosphere (UTLS). © 2012 Elsevier B.V.

Mohapatra M.,Mausam Bhawan | Mandal G.S.,National Disaster Management Authority | Bandyopadhyay B.K.,Mausam Bhawan | Tyagi A.,Mausam Bhawan | Mohanty U.C.,Indian Institute of Technology Delhi
Natural Hazards | Year: 2012

Hazards associated with tropical cyclones are long-duration rotatory high-velocity winds, very heavy rain and storm tide. India has a coastline of about 7,516 km of which 5,400 km is along the mainland. The entire coast is affected by cyclones with varying frequency and intensity. The India Meteorological Department (IMD) is the nodal government agency that provides weather services related to cyclones in India. However, IMD has not identified cyclone-prone districts following any specific definition though the districts for which cyclone warnings are issued have been identified. On the other hand, for the purpose of better cyclone disaster management in the country, it is necessary to define cyclone proneness and identify cyclone-prone coastal districts. It is also necessary to decide degree of hazard proneness of a district by considering cyclone parameters so that mitigation measures are prioritised. In this context, an attempt has been made to prepare a list of cyclone hazard prone districts by adopting hazard criteria. Out of 96 districts under consideration, 12, 45, 31 and 08 districts are in very high, high, moderate and low categories of proneness, respectively. In general, the coastal districts of West Bengal, Orissa, Andhra Pradesh and Tamil Nadu are more prone and are in the high to very high category. The cyclone hazard proneness factor is very high for the districts of Nellore, East Godawari, and Krishna in Andhra Pradesh; Yanam in Puducherry; Balasore, Bhadrak, Kendrapara and Jagatsinghpur in Orissa; and South and North 24 Parganas, Medinipur and Kolkata in West Bengal. The results give a realistic picture of degree of cyclone hazard proneness of districts, as they represent the frequency and intensity of land falling cyclones along with all other hazards like rainfall, wind and storm surge. The categorisation of districts with degree of proneness also tallies with observed pictures. Therefore, this classification of coastal districts based on hazard may be considered for all the required purposes including coastal zone management and planning. However, the vulnerability of the place has not been taken into consideration. Therefore, composite cyclone risk of a district, which is the product of hazard and vulnerability, needs to be assessed separately through detailed study. © 2011 Springer Science+Business Media B.V.

Kumar A.,National Center for Medium Range Weather Forecasting | Mitra A.K.,National Center for Medium Range Weather Forecasting | Bohra A.K.,National Center for Medium Range Weather Forecasting | Iyengar G.R.,National Center for Medium Range Weather Forecasting | Durai V.R.,Mausam Bhawan
Meteorological Applications | Year: 2012

The prediction of Asian summer monsoon rainfall on various space and time scales is still a difficult task. Compared to the mid-latitudes, proportional improvement in the skill in prediction of monsoon rainfall in medium range has been less in recent years. Global models and data assimilation techniques are being further improved for monsoons and the tropics. However, multi-model ensemble (MME) forecasting is gaining popularity, as it has the potential to provide more information for practical forecasting in terms of making a consensus forecast and reducing the model uncertainties. As major centres are exchanging the model output in near real time, MME is a viable, inexpensive, way for enhancing the forecast skill. Apart from a simple ensemble mean, the MME predictions of large-scale monsoon precipitation in the medium range was carried out during the 2009 monsoon at NCMRWF/MoES, India. The neural network weights were obtained and a neural network was trained based upon forecast data from four global models for the 2007 and 2008 monsoons in order to develop the multi-model ensemble system. The skill score for country and sub-regions, indicates that a multi-model ensemble forecast has a higher skill than individual model forecasts and also higher skill than the simple ensemble mean in general. Although the skill of the global models falls beyond day 3, a significant improvement could be seen by employing the MME technique up to day 5. © 2011 Royal Meteorological Society.

Mohapatra M.,Mausam Bhawan
Journal of Earth System Science | Year: 2015

Hazards associated with tropical cyclones (TCs) are long-duration rotatory high velocity winds, very heavy rain, and storm tide. India has a coastline of about 7516 km of which 5400 km is along the mainland. The entire coast is affected by cyclones with varying frequency and intensity. Thus classification of TC hazard proneness of the coastal districts is very essential for planning and preparedness aspects of management of TCs. So, an attempt has been made to classify TC hazard proneness of districts by adopting a hazard criteria based on frequency and intensity of cyclone, wind strength, probable maximum precipitation, and probable maximum storm surge. Ninety-six districts including 72 districts touching the coast and 24 districts not touching the coast, but lying within 100 km from the coast have been classified based on their proneness. Out of 96 districts, 12 are very highly prone, 41 are highly prone, 30 are moderately prone, and the remaining 13 districts are less prone. This classification of coastal districts based on hazard may be considered for all the required purposes including coastal zone management and planning. However, the vulnerability of the place has not been taken into consideration. Therefore, composite cyclone risk of a district, which is the product of hazard and vulnerability, needs to be assessed separately through a detailed study. © Indian Academy of Sciences.

Singh K.K.,Mausam Bhawan | Mall R.K.,Banaras Hindu University | Singh R.S.,National Institute of Disaster management | Srivastava A.K.,Indian Institute of Sugarcane Research
Journal of Agrometeorology | Year: 2010

The sugarcane crop growth simulation model was calibrated and validated in Eastern Uttar Pradesh (UP) region of Indo-Gangetic Plains of India using 12 years field experiment data conducted in several places. The results reveal that the CANEGRO Sugarcane model satisfactorily simulated the potential growth and yield of sugarcane crop. The model simulates the stalk height, stalk fresh mass and sucrose yield within ±15% of range in comparison to the observed values. Therefore the validated CANEGRO Sugarcane model can be further used for applications such as prediction of crop growth, phenology, water management, potential and actual yields, performance of sugarcane under climate variability and change scenarios etc. The model may also be used to improve and evaluate the current practices of sugarcane growth management to achieve enhanced cane production and sugar recovery.

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