bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutions of sea level high and warm pool in the southeastern Arabian Sea and their association with Asian monsoons : A study on cause-and-effect relationships
Authors: SINGH O. P.
Published: November 2021

The present study aims at gaining more insight into the evolution of warm pool and associated sea level dome in the southeastern Arabian Sea before the summer monsoon onset.  The results show that the Sea Surface Temperature (SST) maximum in the warm pool region is found during April close to the southwest coast of India.  The Sea Surface Height (SSH) maximum over the same region is observed during December. The collapse of sea level dome begins well in advance during the pre-monsoon whereas the warm pool collapses after the onset of summer monsoon during June.  Therefore, there is a lag of about three to four months between the collapses of the sea level high and the warm pool.  Most interesting aspect is the dramatic increase of SST from September and SSH from October which is continued throughout the post monsoon season (October - December). Therefore, both the collapse and evolution of warm pool are dramatic events before and after the summer monsoon. 

                 

There are considerable variations in the intensity of warm pool and the height of sea level dome on interannual scale.  The variation during El-Nino Southern Oscillation (ENSO) epoch of 1987-88 has revealed many interesting features.  During El-Nino year 1987 the warm pool intensity reached its peak in June whereas during La Nina year 1988 the warm pool attained its maximum intensity much earlier, i.e., in April.
Seasonal forecasts of Indian summer monsoon rainfall using local polynomial based non-parametric regression model
Authors: ROHILLA ANIL KUMAR , RAJEEVAN M. , PAI D. S.
Published: November 2021

In this paper, details of new statistical models for forecasting southwest monsoon (June-September) rainfall over India (ISMR) and for northwest India summer monsoon rainfall (NWISMR) are discussed. These models are based on the local polynomial based non-parametric regression method.  Two predictor sets (SET-I & SET-II consisting of 4 and 5 predictors respectively) were selected for developing two separate models for making predictions in April and late June respectively. Another predictor set (SET-III) was selected for developing model for monsoon rainfall over NW India (NWISMR). Principle Component Analysis (PCA) of predictor data set was done and the first two principal components were selected for model development. Data for the period 1977-2005 have been used for developing the model and the Jackknife method was used to assess the skill of the model. Both the models showed useful skill in predicting ISMR and showed better performance than the model based on pure climatology.  The Hit scores for the three category forecasts during the verification period by April and June models are 0.65 and 0.66 respectively. Root Mean Square Error (RMSE) of these models during the verification period is 5.99 and 6.0% respectively from the Long Period Average (LPA) as against 10.0% from the LPA of the model based on climatology alone.  RMSE of the Northwest India model during the independent period is 11.5% from LPA as against 18.5% from the LPA of the model based on the climatology alone. Hit score for the three category forecast for NW India during the verification period is 0.55.
Spatial and temporal characteristics of evaporation trends over India during 1971-2000
Authors: JASWAL A. K. , RAO G. S. PRAKASA , DE U. S.
Published: November 2021

Evaporation and rainfall data for the period 1971-2000 for 58 well distributed stations over India were selected for this study. Trends of these two parameters for the country as a whole and for individual stations for annual (January – December), winter (December, January and February), summer (March – May), monsoon (June – September) and post-monsoon (October, November) period were analysed and tested for significance at 95% level of confidence. The analysis shows that for the country as a whole, the evaporation has significantly decreased in all seasons while there is no significant trend in rainfall. Out of 58 stations, numbers of stations having significant decrease in evaporation are 45 (annual), 30 (winter), 42 (summer) and 35 (monsoon and post monsoon seasons). Decadal analysis of trends shows that the variability of evaporation towards the decreasing trend is steadily maintained throughout the period but more in the decade 1991-2000. Spatial analysis of the seasonal trends of evaporation indicates the decreasing trends over all parts of India except northeast where it is increasing. Regions of significant decrease in evaporation viz., North, Southwest and Southeast and increase in evaporation viz., Northeast emerge from the spatial analysis of trends over the country. Spatial analysis of seasonal rainfall trends indicates the increasing trends in southern parts and decreasing trends in central and northeastern parts of the country. Evaporation trends of nearly 50% stations (mostly in southern parts of India) show complimentary relation with rainfall of the same period. Rest of the long term trends in evaporation may be due to the variation in other parameters like wind speed, cloud cover, sunshine duration etc. which needs further examination.
Climatology of blizzards over Schirmacher Oasis, east Antarctica
Authors: LAL R. P. , RAM SURESH
Published: November 2021

Weather in Antarctica is subject to frequent and sudden changes.  Strong winds and blizzards dominate Antarctic weather. A combination of blowing snow, gale force wind and very low visibility is normally defined as blizzard. Meteorological data recorded at Indian Antarctic Station Maitri, in respect of blizzards recorded during the period 1990-2005 has been studied to find out climatological features of blizzards affecting Schirmacher Oasis.

 

    At Maitri the blizzard is mostly associated with extra-tropical storms and is normally preceded by precipitation. On average during the year about 21 blizzards affects the station for 45 days during the year. During the month of April to August 3 to 4 blizzards affects the station. Maximum number of blizzards occurs in the month of August with about 7 blizzard days. Average wind speed recorded during the blizzard is about 52 kt but it exceeded 100 kt on several occasions. The duration may vary from hours to days with average of 25 hours. Longest duration of 168 hours was recorded in June 1997. There are about 12 such occasions when blizzard lasted more than 72 hours. No correlation has been found between maximum wind speed and temperature rise during blizzard and the speed is also not correlated with pressure departure during the period.
Evaluation of different convective schemes on simulation of thunderstorm event over Delhi by ARPS Model
Authors: SRIVASTAVA KULDEEP , BHOWMIK S. K. ROY , HATWAR H. R.
Published: November 2021

Three difference cumulus parameterization schemes namely, Kain-Fritsch, New Kain-Fritsch and the Betts-Miller-Janjic are used to simulated convective rainfall associated with two thunderstorm events over Delhi by Advanced Regional Prediction Model (ARPS). An inter comparison of model simulated precipitation in respect of each convection scheme is made with reference to observed precipitation. The study shows that for the Delhi thunderstorm events, the Kain-Fritsch scheme provides more realistic results. This scheme is able to capture the temporal distribution of rainfall and the timely development of thunderstorm in both the cases. While the other two schemes fail to capture these features. However, the Kain-Fritsch scheme is found to overestimate the rainfall amount.
Verification of heavy rainfall warning over Bihar and Uttar Pradesh
Authors: MOHAPATRA M. , HATWAR H. R. , KALSI S. R.
Published: November 2021

India Meteorological Department (IMD) issues heavy rainfall warning for a meteorological sub-division when the expected 24 hours rainfall over any rain gauge station in that sub-division is likely to be 64.5 mm or more. Though these warnings have been provided since long and are also now being issued for smaller spatial scales, very few attempts have been made for quantitative evaluation of these warnings.  Hence, a study is undertaken to verify the heavy rainfall warning over the representative meteorological sub-divisions of east Uttar Pradesh (UP), west UP and Bihar during main monsoon months of July and August. For this purpose data of the recent 5 years (2001-2005) and also for another epoch of 5 years in the early 1970s has been taken into consideration. In this connection, the day when heavy rainfall is recorded over atleast two stations in a sub-division, has been considered as a heavy rainfall day for that sub-division.

 

This study of verification shows that probability of detection of heavy rainfall is 64% over Bihar, 52% over east UP and 53% over west UP for the recent 5 years. Compared to early 1970s, there has been slight improvement in the forecast skill during 2001-2005 with probability of detection increasing by about 10-20% and with decrease in missing rate and false alarm rate. However, the false alarm rates are still large indicating higher bias towards over-prediction. The synoptic conditions associated with the heavy rainfall events have been collected for the period 2001-05 and analysed. The analysis of the unanticipated heavy rainfall events suggests that though proper interpretation of synoptic charts and NWP outputs could improve the warnings, the forecast system available even today is still not capable to capture every heavy rain event in advance.
Precipitation regionalization of southwest monsoon by hierarchical cluster analysis
Authors: MAZUMDAR A. B.
Published: November 2021

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.
A study on parameters controlling water requirement of rice (Oryza sativa L.) at various phenophases in different agroclimatic zones
Authors: KASHYAPI A. , DAS H. P. , HAGE A. P. , KALE A. A.
Published: November 2021

The parameters controlling water requirement of rice crop and other crop related data were collected and computed at eleven critical phenophases, from eight different ET – stations, for latest available five years and the mean values were analyzed. The study revealed that the total water requirement – demand   for rice crop in different rice growing ET – stations varied from 411.3 to 688.7 mm of water. In most of the stations peak ET was recorded during tillering to active tillering stages, which contributed 27 – 38 per cent of the total water need of the crop. The seasonal rainfall in most of the stations was sufficient to meet the ET requirement at various growth stages. However, few stations recorded high yield due to assured irrigation facility. The average Kc values (throughout the crop growth period) showed variation from 0.77 to 1.13 among different stations studied. For most of the stations  Kc values reached their  peak mostly at active tillering stage onward. At some stations six or more growth stages recorded Kc values even more than one. Rice yield varied from 1839 kg/ha to 5892 kg/ha. Also, the crop productivity varied   widely from 15.074 to 51.684  kg/ha/day. The WUE of the crop in different stations laid between 3.68 to 10.71 kg/ha/mm.
Secular variations and trends in the occurrence of monsoon synoptic systems and its impact on central India rainfall
Authors: RASE D. M. , SHEVALE M. P. , RIZVI S. I. M.
Published: November 2021

Importance of monsoon depressions, Low Pressure Systems (LPS) and the number of LPS days on rainfall and hence indirectly on agriculture and hydrology, is well recognized.

 

   In this paper the pattern of annual variability in these systems have been examined using data from 1901-2000. The above mentioned parameters have been subjected to decadal analysis to detect presence of any regular pattern. An attempt has been made to find its tendency with time.  Impact of these systems on central India rainfall has been determined and discussed. 

 

 The study endorses the earlier findings that there is a   decreasing trend in the frequency of depressions which has been compensated with increase in LPS days over Indian region in recent years.  The rainfall over central India is more significantly related with a number of LPS days over Indian region.
Characteristics of thunderstorms and squalls over Indira Gandhi International (IGI) airport, New Delhi - Impact on environment especially on summer’s day temperatures and use in forecasting
Authors: JENAMANI R. K. , VASHISTH R. C. , BHAN S. C.
Published: November 2021

In the present study, commencement timings and duration of thunderstorms (TS) and squalls at IGI airport, Palam, New Delhi have been analysed critically based on most recent eleven years data of 1995-2005 to find their favourable time of occurrences. Then utility of such data base in the aviation warning has been demonstrated. Environmental changes associated with these squalls have also been further analysed to understand their impact. Being recent May 2007 a very cool month over Delhi, the role of TS on controlling the day’s soaring temperature has also been studied from their data.  Results show TS are maximum in June followed by July whereas squalls are maximum in May followed by June. It shows more than 80% of TS in each season are of duration less than 3 hours with remaining are mostly 3 to 6 hours. The peak time period of commencement of both TS and squalls in the day differ with the progress of the months. For pre monsoon months, the most favourable timing of TS and squalls are 1200-1500 UTC while for monsoon, it starts earlier. Around 37% of the total TS during the period were associated with squalls. The average maximum wind speed in squall at IGI airport is about 68 kmph with highest maximum wind speed 139 kmph. On an average the environmental temperature falls by 5.6° C, humidity levels rises by 17.8% and mean sea level pressure rises by 1.6 hPa due to the occurrences of squalls. Study also shows daily maximum temperature rise is highly controlled by TS occurrences and May 2007, being a month of highest TS occurrences at the airport since 1995, became one of the coolest month in May over Delhi. The comparison of TS frequencies shows 12% increase in their annual activities since 1950-1980 with very high unusual increase of 51% in June and 26% in May. Since analysis of data from 1995 shows occurrences of TS are reversely but strongly correlated with summer temperatures and longer period temperature data since 1975 also confirms absence of significant trend in maximum temperature and higher temperature days in peak summer months of May and June till recent as expected due to high pollution, global warming and fast urbanization in the city, so it is the higher number of TS occurrences over the region from time to time which might have been main factor for controlling its significant rise.
Evaluation of heavy rainfall warning over India during summer monsoon season
Authors: MOHAPATRA M. , HATWAR H. R. , BANDYOPADHYAY B. K. , SUBRAHMANYAM V.
Published: November 2021

India Meteorological Department (IMD) issues heavy rainfall warning for a meteorological sub-division when the expected 24 hours rainfall over any rain gauge station in that sub-division is likely to be 64.5 mm or more. Though these warnings have been provided since the inception of IMD, a few attempts have been made for quantitative evaluation of these warnings.  Hence, a study is undertaken to verify the heavy rainfall warnings over 36 meteorological sub-divisions of India during monsoon months (June-September) and season as a whole. For this purpose, data of recent 5 years (2002-2006) has been taken into consideration. In this connection, the day when heavy rainfall is recorded over at least one station in a sub-division, has been considered as a heavy rainfall day for that sub-division.

 

There is a large spatial and temporal variability in skill scores of heavy rainfall warnings over India during summer monsoon season. Considering the monsoon season as a whole, the Heidke Skill Score (HSS) is relatively less (<0.20) over the regions with less frequent heavy rainfall like Lakshadweep, southeast peninsula, Vidarbha, Marathwada, Jammu & Kashmir, Arunachal Pradesh and Nagaland, Manipur, Mizoram & Tripura (NMMT). It is higher (> 0.50) over Konkan & Goa, Madhya Maharashtra and Gujarat region. There has been improvement in the forecast skill with gradual increase in the critical success index and Heidke skill score over the years mainly due to the Numerical Weather Prediction (NWP) models' guidance available to the forecasters. However, the false alarm rate and missing rate are still very high (> 0.50), especially over many sub-divisions of northwest India, southeast peninsula and NMMT.
Real time forecasting of the Bay of Bengal cyclonic storm “RASHMI” of October 2008 – A statistical-dynamical approach
Authors: KOTAL S. D. , BHOWMIK S. K. ROY , MUKHOPADHYAY B.
Published: November 2021

A four-step statistical-dynamical approach is applied for real time forecasting of the Bay of Bengal cyclonic storm “RASHMI” of October 2008 which made landfall near Khepupara (Bangladesh) around 2200 UTC of 26 October 2008. The four-step approach consists of (a) Analysis of Genesis Potential Parameter (GPP), (b) Track prediction, (c) Intensity Prediction by Statistical Cyclone Intensity Prediction (SCIP) model and (d) Prediction of decaying intensity after the landfall. The results show that the analysis of Genesis Potential Parameter (GPP) at early stages of development strongly indicated that the cyclone “RASHMI” had enough potential to reach its cyclone stage.  The 48 hours landfall forecast position error based on 0000 UTC on 25 October shows that the error varies from around 10 km to 95 km and landfall time error varies from 12 hours early to 23 hours delay by different numerical models (NWP). The consensus forecast (ensemble) based on these NWP models shows that landfall forecast position error is around 10 km and landfall time error is around 2 hours delay. The updated 24 hours forecast based on 0000 UTC of 26 October shows improvement in the forecast. The model predicted landfall position error varies from around 10 km to 55 km with landfall time 6 hours early to 3 hours delay. The Multiple Model Ensemble (MME) forecast shows that the landfall forecast position is close to observed landfall point and the landfall time is early by 2 hours. The JMA (Japan Meteorological Agency) and ensemble forecasts are found to be consistent both in terms of 24-hourly forecasts position, landfall point and landfall time. The 12–hourly intensity prediction up to 24 hours forecasts based on 0000 UTC on 26 October show that the model (SCIP) could pick up the intensification of the cyclone. The model forecasts till the landfall point show that there is an underestimation of intensity by 2 knots and 8 knots at 12 hour and 24 hour forecasts respectively. The 6-hourly decaying intensity forecast after the landfall shows an overestimation of 6 knots and 10 knots at 6-hour and 12-hour forecasts respectively. The approach provided useful guidance to the forecasters for real time forecasting of the cyclone.
Fractal analysis: Annual rainfall in Chennai
Authors: SELVARAJ R. SAMUEL , TAMILSELVI S. , GAYATHRI R.
Published: November 2021

The annual rainfall data of Chennai is analyzed using the Fractal Construction Technique. According to Mandelbrot the dimension of any line including nautical lines may not be Euclidean but Fractional, Mandelbrot, 1982. This fractional dimension leads to a repetitive appearance of any pattern. Climate which is usually periodic by nature can be analyzed through this technique. Efforts are on to search the fractal geometry of climate and to predict its periodicity on different temporal scales. This paper estimates the various parameters like Lyapunov exponent, Maximum Lyapunov characteristic exponent, Lyapunov time, Kaplan-Yorke dimension for the annual rainfall of Chennai.
Erraticness of the rainfalls in different regions of India
Authors: KANE R. P.
Published: November 2021

In the different regions of India, there is no evidence of rainfalls being more erratic (larger standard deviations) in more recent years. In the past, the peaks seem to have occurred during 1880-1890 and 1950-1960 in some regions, a separation of ~70 years. If meaningful, it could be indicative of a likely peak during 2020-2030.
Crop coefficient and water requirement of Okra (Abelmoschus Esculentus L. Moench)
Authors: PATIL CHANABASANAGOUDA. S.
Published: November 2021

Based on the result of an experiment conducted   from 1997 to 1999 during  March-July,  a model has been developed for relating crop coefficient of okra with time at Bangalore. The peak value of crop co-efficient was found to be 1.16 on the 9th week after sowing. On an average okra crop consumed about 547 mm of water during the growth.  The mean   values of crop coefficients are found to be 0.46, 1.29 and 0.66 during seedling, pod development and maturity stages respectively.
Performance evaluation of precipitation prediction skill of NCEP Global Forecasting System (GFS) over Indian region during summer monsoon 2008
Authors: DURAI V. R. , BHOWMIK S. K. ROY , MUKHOPADHYAY B.
Published: November 2021

The study provides a concise and synthesized documentation of the current level of skill of the NCEP GFS day-1 to day-5 precipitation forecasts during Indian summer monsoon of 2008, making detailed inter-comparison with daily rainfall analysis from the use of rain gauge observations and satellite (KALPANA-1) derived Quantitative Precipitation Estimates (QPE) obtained from IMD. Model performance is evaluated for day-1 to day-5 forecasts of 24-hr accumulated precipitation in terms of several accuracy and skill measures. Forecast quality and potential value are found to depend strongly on the verification dataset, geographic region and precipitation threshold. Precipitation forecasts of the model, when accumulated over the whole season, reproduce the observed pattern. However, the model predicted rainfall is comparatively higher than the observed rainfall over most parts of the country during the season. The model showed considerable skill in predicting the daily and seasonal mean rainfall over all India and also over four broad homogeneous regions of India. The model bias for rainfall prediction changes from overestimation to underestimation at the threshold of 25 mm/day except for day-1 forecast. Model skill falls dramatically for occurrence rainfall thresholds greater than 10 mm/day. This implies that the model is much better at predicting the occurrence of rainfall than they are at predicting the magnitude and location of the peak values. Various skill score and categorical statistics for the NCEP GFS model rainfall forecast for monsoon 2008 are prepared and discussed.
Study of rainfall features over Goa state during southwest monsoon season
Authors: METRI S. M. , SINGH KHUSHVIR
Published: November 2021

In this paper the rainfall features at different raingauge stations of Goa state have been studied for the period of 30 years. The statistical parameters such as mean monthly rainfall, Standard Deviation and Coefficient of Variation have been computed for each raingauge station of Goa. Some heavy rainfall events during the period have also been studied. The study shows the significant rising trend of rainfall towards the eastern parts of Goa. Goa experiences an average rainfall of about 330 cm annually and around 90% of annual rainfall occurs during southwest monsoon season i.e. (June to September). Studies revealed that most of heavy rainfall events caused due to active off-shore trough and low pressure systems formed over southeast Arabian Sea. It has also come out from the study that the orography of Goa plays an important role in rainfall distribution. Valpoi receives maximum rainfall due to its orographic effect.
Effect of broadcast and precise satellite orbits in the estimation of Zenith tropospheric delay and integrated precipitable water vapour from GPS
Authors: YADAV J. K. S. , GIRI R. K. , MALIK D. K.
Published: November 2021

Global Positioning System (GPS) estimates the total delay in zenith direction by the propagation delay of the neutral atmosphere in presence of water vapour present in the troposphere. This total delay has been treated as a nuisance parameter for many years by the geodesists. The above delay have two parts dry delay and wet delay and known as Zenith Hydrostatic Delay (ZHD) and Zenith Wet Delay (ZWD) respectively. The Integrated Precipitable Water Vapour (IPWV) is estimated through ZWD overlying the receiver at ground-based station. The accuracy of the above said estimates depends on the quality of the predicted satellite orbits, which are not the same for each individual satellite. India Meteorological Department (IMD) is operationally estimating the IPWV on near real time basis at five places and matches fairly well (error ~6.7 mm) with Radisonde (RS) data. This paper examine the effect of International GPS Service (IGS) predicted precise orbits and near real time predicted rapid or broadcast orbits supplied by the Scripps Orbit and Permanent Array Center (SOPAC) on Zenith Total Delay (ZTD) and IPWV estimates by calculating the mean Bias and Root Mean Square Error (RMSE) for ZTD and IPWV in mm for all the five stations. The observed bias for ZTD is almost of the order of less than 1 mm in most cases and RMSE is less than 6 mm. Similarly the bias observed in the case of derived IPWV is almost negligible and RMSE is less than 1 mm.
Impact of AMDAR observations from Lufthansa aircraft on Global Analysis - Forecast System
Authors: DUTTA SURYA K. , GUPTA MUNMUN DAS , PRASAD V. S.
Published: November 2021

AMDAR observations from Lufthansa and Lufthansa cargo aircrafts in BUFR format (with header IUADOI EGGR and IUAHOI EGRR) were made available to India Meteorological Department (IMD) and in turn to National Centre for Medium Range Weather Forecasting (NCMRWF) under special arrangement for a period of two weeks w.e.f. 14th May 2008. These data have been assimilated at NCMRWF (National Centre for Medium Range Weather Forecasting) model for the period 14th - 31st May, 2008 to assess its impact on NWP. Use of these observations gave some positive impact on NWP systems.
Development of weather based prediction model for leaf roller population of Sesame in Bundelkhand zone of Madhya Pradesh
Authors: GUPTA M. P. , SRIVASTAVA A. K. , NAYAK M. K.
Published: November 2021

Field experiment was conducted during twelve consecutive Kharif seasons from 1995 to 2006 at Zonal Agricultural Research Station, Tikamgarh to find out the impact of weather parameters on the incidence and activity of Antigastra catalaunalis (Dupnocbel) in Sesame cv JT-7. The analysis revealed that the pest activity started to buildup from 30th standard meteorological week and remained up to 40th standard meteorological weeks (SMW). Larval population has been correlated with weather data and correlation coefficient, regression equations were worked out for development of weather based prediction model. Significant positive correlation with maximum and mean temperature (maximum, minimum) and negative relationships with rainfall was observed. Best fitted polynomial models were developed using the whole season data which explained 60 to 90 per cent variability due to weather parameters. The multiple regression technique has been used for developing predictive model using larval population and weather data not only for the corresponding week but also for preceding weeks. The prediction model for leaf roller explained 88% variability of the pest population. The model predicted peak larval population was in good agreement with observed peak larval population.
Semi quantitative forecasts for Baghmati/Adhwara Group of rivers/Kamala Balan catchments by synoptic analogue technique
Authors: SINGH K. M. , PRASAD M. C. , PRASAD G.
Published: November 2021

An attempt has been made to issue semi-quantitative precipitation forecasts for Baghmati/Adhwara Group of rivers/Kamala-Balan catchments based upon 22 years data (1982-2003). The study reveals that it is possible to issue semi-quantitative precipitation forecast with confidence. Local topography and its steep gradient on Indo-Nepal Border are main factors that give birth to severe floods during south west monsoon and pose problems to Darbhanga City.
A severe hailstorm over Guwahati airport and its vicinity on 2nd April 2006 : Synoptic and thermodynamic perspectives
Authors: BISWAS H. R. , DAS G. K. , CHAKRABARTI D. , KORE P. A.
Published: November 2021

Climatologically thunderstorm activity is quite common features over Guwahati Airport and its vicinity during premonsoon season. But a severe hailstorm with large size of hailstones and long duration is a rare event. Such a hailstorm with hailstone size of about 25mm occurred over Guwahati Airport (26.1°N, 91.6°E) on 2nd April, 2006 during midnight. In this paper an attempt has been made to investigate prerequisite synoptic and thermodynamic conditions of the atmosphere associated with this hailstorm. Under favourable synoptic and instability condition of thunderstorm occurrence, veering of winds over Guwahati between freezing level and 500 hPa level with vertical wind shear of horizontal winds exceeding 6.2 ms-1km-1 more appears to be conductive for the development of a hailstorm. Stability Indices viz., Showalter, K, Total-Total and Severe Weather Threat (SWEAT) index have shown predictability for this event.
Drought monitoring over India through Normalized Difference Vegetation Index (NDVI)
Authors: KAMBLE M. V. , GHOSH K. , RAJEEVAN M. , SAMUI R. P.
Published: November 2021

Normalized Difference Vegetation Index (NDVI) is a simple index to monitor the state of vegetation (stressed/unstressed) which can be derived from satellite data. Hence an attempt is made to find out the vegetation responses to rainfall through NDVI over the study area. Applicability of NDVI in drought monitoring is discussed using the NDVI and rainfall data for the period 1982-2003. The anomaly of NDVI is compared with the percentage departure of rainfall of corresponding years. Results showed a significant relation between the NDVI with the percentage departure of rainfall. The time series plots of averaged NDVI and seasonal rainfall (June-September) are done for NW India (21° N - 31° N, 68° E - 78° E), Central India (22° N - 27° N, 70° E - 77° E) and Peninsular India (16° N - 21° N, 74° E - 79° E) over the period 1982-2003 to analyze changes in vegetation pattern of India during the last two decades. Results indicated a clear linear relationship over NW and Central India. NDVI anomalies and the corresponding cumulative rainfall showed significantly linear correlation of 0.69 over NW India and 0.57 over Central India significant at 1% level but the correlation is found to be insignificant over Peninsular India which was only 0.04. Trend analysis of averaged NDVI over India showed that during last two decades the vegetation status had quite improved over the dry farming tracts of India.
Comparison of spatial interpolation methods for estimation of weekly rainfall in West Bengal, India
Authors: DAS MADHURIMA , HAZRA ARNAB , SARKAR ADITI , BHATTACHARYA SABYASACHI , BANIK PABITRA
Published: December 2021

Rainfall is one of the most eloquently researched contemporary meteorological phenomena affecting the agricultural practices dramatically, particularly along the humid, sub-tropics, where agriculture is predominantly rainfed. It is a key parameter of agricultural production in West Bengal due to lack irrigation facilities in most of the areas. Thus, it is very important to have detailed information of rainfall distribution pattern of West Bengal. In practice rainfall data is collected only at few discrete stations scattered all over the whole state. However, rainfall is a spatially continuous phenomenon rather than discrete. Thus it becomes essential to apply a robust spatial interpolation technique to transform the discrete values into a continuous spatial pattern. In the present study, three spatial interpolation techniques namely Kriging, Inverse Distance Weighted (IDW) and SPLINE, are used for a comparative analysis to identify the most efficient interpolation technique. Weekly average rainfall data available between 1901 and 1985 for 19 standard meteorological weeks (SMW), Week 22 to Week 40 are used for the analysis. The errors of the three interpolation techniques are analyzed and the best method is chosen based on the minimum mean absolute deviation (MAD) and the minimum mean squared deviation (MSD) criteria. The IDW method is found to be the best spatial interpolation technique.
Os "carrinhos de balinha": um recorte na história dos vendedores ambulantes
Authors: Santos Rosana de Oliveira Gomes , Da Silva Ana Paula Bispo
Published: December 2021

O presente artigo tem o objetivo de explorar a biografia de um objeto, “carrinho de balinha”, como parte da cultura material e da história dos vendedores ambulantes. A cultura material possibilita nos aproximar da história por detrás de um objeto considerando seus aspectos sociais, econômicos e culturais, além do que ele representou para uma sociedade. Utilizamos a abordagem sobre a cultura material na perspectiva de Prown (1982), seguindo as quatro operações para analisar o objeto, e o método de interpretação de Geertz (2019), para interpretar os significados que são atribuídos ao objeto. Discorremos sobre a importância que o objeto pessoal teve para enfrentar a realidade social da economia vivida na década de 80 e a superação dessa realidade com a utilização do “carrinho de balinha”.
As potencialidades dos objetos para a construção da identidade: o caso da Faculdade de Enfermagem.
Authors: Ribeiro Diego Lemos , Gutierre Marina Duarte
Published: December 2021

O trabalho apresentado investiga a vontade de memória da Faculdade de Enfermagem da Universidade Federal de Pelotas, demonstrada através do ato de selecionar objetos que representam seu fazer profissional e sua caminhada institucional. A seleção de objetos implica na compreensão de conceitos relacionados à coleção e no trajeto até essa definição. Além disso, refletirá sobre a potencialidade que os objetos preservados têm - ou podem adquirir- na construção da memória e identidade do grupo estudado, e como esse potencial é afetado pela forma como são exibidos.
Features of the Propane Combustion in the Round and Plane Macro- and Micro-Jet in a Transverse Acoustic Field at the Small Reynolds Number
Authors: Grek Genrich , Katasonov Mikhail , Kozlov Viktor , Korobeinichev Oleg , Litvinenko Yuriy , Shmakov Andrey
Published: December 2021

Results of experimental studies on round and plane macro- and micro-jets with top-hat and parabolic mean velocity profile at the nozzle exit subjected to transverse acoustic field at small Reynolds number are presented in this review. Features of their evolution in the given conditions are shown. On the basis of the received knowledge the new phenomena uncovered at study of the flame evolution in a transverse acoustic field by the propane round and plane micro-jet combustion are revealed and explained
Numerical and Analytical Estimation of Parameters of Pulsed Energy Sources Which Do Not Lead to Locking of Supersonic Flow in Channels of Variable Section
Authors: Zamuraev Vladimir , Kalinina Anna
Published: December 2021

In this paper the pulse energy supply into the channel of variable cross section was studied. The approximate formulas were obtained for the value of the input energy, corresponding to the maximal distance which the shock wave from a pulsed power source reached upstream, as well as full power, energy supply period corresponding to the conditions of closing the channel. The applicability of the analytical relationships is confirmed by numerical calculations based on the Euler equations in a quasi one-dimensional approximation
The Parametric IR Lasers with High Radiation Efficiency Over the Entirerange of Frequency Tuning
Authors: Airapetyan Valerik , Shirokova Tamara , Pasko Petr
Published: December 2021

Computational and experimental studies of the lasing characteristics of IR optical parametric oscillator (OPO) on the nonlinear crystal LiNbO3 were performed. Implemented outside the cavity ring scheme OPO with replaceable output mirrors allows the conversion of the pump frequency in parametric generation to 30 % over the tuning range from 1.41 to 4.24 microns
An Experimental and Numerical Study of a Supersonic Overexpanded Jet Gas-Dynamic Structure
Authors: Zapryagaev Valeriy , Kavun Ivan , Kundasev Sergey
Published: December 2021

Experimental data about the structure of the supersonic overexpanded jet (Ma=3, n=0.58) is obtained. This data is intended for verification of numerical calculation results. Main factors influencing on the precision of experimental data are shown. Experimental results are supplemented with numerical simulation performed with program package ANSYS Fluent. Differences between experimental and numerical data are analyzed
Software Development Process for Automation System of Large Solar Vacuum Telescope
Authors: Bevzov Alexey , Kurochkin Aleksandr , Lubkov Anatoliy , Petukhov Aleksandr , Filatov Pavel
Published: December 2021

The paper describes experience of software development for automated system for Large Solar Vacuum Telescope. Most attention is given to the work evolution on the different stages of this process. Automated system software has been developed using Object-Oriented Programming, Design Patterns and Qt tools to achieve reusable code, that can be used in other telescopes and be portable to different operating systems
Scheme of Hydrogen Ignition in Duct with Shock Waves
Authors: Goldfeld Marat , Starov Alexey
Published: December 2021

In article results of the analysis of processes of self-ignition and combustion propagation are given in the multi-injector combustion chamber with high supersonic speeds of an air flow. It is established that fuel ignition at high Mach numbers, bringing to flame propagation on all volume of combustor and combustion stabilization, happens not in recirculation area behind a step, and in the field of interaction of shock waves with an boundary layer on walls or behind this area downstream near an angular point of the combustion chamber. The scheme of development of process of combustion in the combustion chamber with significantly three-dimensional configuration is in details considered
Superconducting Resonators: Decrease of Q-Factor at High Accelerating Field
Authors: Dzyuba Aleksandr , Arzhannikov Andrey
Published: December 2021

Results combining efforts of different groups on investigation of losses in superconducting radio frequency cavities made of niobium are presented. Peculiarities of such losses and of their remedies are considered for dissipation at high accelerating voltages. The main results of RF tests as well as main experiments conducted via physico-chemical research methods on samples are discussed. The role of different type of defects on losses is presented. The candidate mechanisms for dissipation are considered based on exhibited results. As a conclusion the prediction is made on possible alternative processing steps for improvement of cost, time and safety efficiency of current technological procedures
The Full Calculation of Three-Dimensional Quasi-Stationary Electromagnetic Fields in Approach of the Strong Skin Effect by the Method of the Boundary Integral Equations
Authors: Tiunov Mikhail
Published: December 2021

The efficient method of the boundary integral equations allowing to carry out the full simulation of three-dimensional quasi-stationary electromagnetic fields in approach of the strong skin effect is devised and realized. Examples of calculations of modeling and real systems of formation of quasistationary electromagnetic fields are given. The comparisons of results of simulation with analytical solutions and observed data are presented
Model of Luminescence Evolution in High-Power Laser Systems Based on Parametric Amplification Cascades
Authors: Frolov Stanislav , Leschenko Vyacheslav , Trunov Vladimir
Published: December 2021

The paper presents the model of parametric luminescence evolution that takes diffraction, birefringence and group velocity dispersion into account. The distinctive feature of the model is capability to compute full frequency-angular spectra of amplified luminescence generated during parametric amplification of chirped pulses. That allows not only to compute pulse contrast but also to estimate influence of superluminescence on energy of amplified pulses. The results of experiments to measure parameters of parametric luminescence generated during parametric amplification of chirped femtosecond pulses in BBO crystals are presented. The comparison of experimental and simulation results shows good agreement between theory and experiment
Three Sectional Drift-Diffusion Mathematical Model Of The Field Effect Transistor With A Schottky Barrier
Authors: Savelkaev Sergey , Airapetyan Valerik , Litovchenko Vladimir
Published: December 2021

Three sectional drift-diffusion mathematical model of the field effect transistor with a Schottky barrier is proposed. It takes into account the accumulation of charge carriers in the additionally introduced third section, which significantly improves the accuracy of the calculation of the current-voltage characteristics flat area of the transistors. This is important for developers of these transistors, as well as for amplifying and autogenerating microwave devices constructors.
Features Of Magnetoresistance In The Bilayer Single Crystal Manganite LA1.4SR1.6MN2O7
Authors: Nikitin Stanislav , Popkov Sergey , Petrov Mikhail , Terent’ev Konstantin , Semenov Sergey , Shaikhutdinov Kirill
Published: December 2021

We investigate magnetoresistance of single-crystal bilayer lanthanum manganite La1.4Sr1.6Mn2O7 at a transport current flowing along the crystal c axis and in external magnetic fields applied parallel to the crystal c axis or ab plane. It is demonstrated that the La1.4Sr1.6Mn2O7 manganite exhibits the positive magnetoresistance effect in the magnetic field applied in the ab plane of the sample at the temperatures T < 60 K. The mechanism of this effect is shown to be fundamentally different from the colossal magnetoresistance effect typical of lanthanum manganites. The positive magnetoresistance originates from spin-dependent tunneling of carriers between the manganese-oxygen bilayers and can be explained by features of the magnetic structure of the investigated compounds.
On The Influence Of Porous Coating Thickness On Supersonic Boundary Layer Stability
Authors: Lysenko Vladimir , Gaponov Sergey , Smorodsky Boris , Yermolaev Yuri , Kosinov Aleksandr , Semionov Nikolay
Published: December 2021

Theoretical and experimental investigation of the influence of porous-coating thickness on the stability of the supersonic flat-plate boundary layer at free-stream Mach number M = 2 have been performed. Good quantitative agreement of experimental data obtained with artificially generated disturbances performed on models with various porous inserts and calculations based on the linear stability theory has been achieved. It is shown that the increase of the porous-coating thickness leads to the boundary layer destabilization.
Analys Of Modification Of The Heat Resistant Alloy By Nano-Size Refractory Particles
Authors: Cherepanov Anatoliy , Popov Vladimir
Published: December 2021

The iron-nickel alloy Inkonel-718 is taken an example to consider the material modification with the powders of refractory compositions. Under consideration are theoretical and experimental analysis of the modifiers effect on crystallization kinetics, structuring and mechanical properties of the solidified alloy.
Features Of The Diffusion Combustion Of Hydrogen Microjet At Various Spatial Orientation Of The Nozzle Exit
Authors: Grek Genrich , Kozlov Viktor , Korobeinichev Oleg , Litvinenko Yuriy , Shmakov Andrey
Published: December 2021

The purpose of the given work will consist in the experimental studies of features diffusion combustion of a hydrogen round microjet depending on spatial orientation of the nozzle exit. It is revealed, that a hydrogen round microjet at diffusion combustion in conditions of a jet velocity vector orientation towards terrestrial gravitation vector «g» (opposite or perpendicular) the basic characteristics of the flame evolution depending on a jet velocity are practically coincided. To these characteristics concern such as ranges of the «bottleneck» flame area presence, flame detachment at presence of the «bottleneck» flame area, presence of the «bottleneck» flame area, but absence of a turbulent jet combustion and finally ending of the microjet combustion. On the contrary, in situation of the hydrogen round microjet diffusion combustion in conditions of a jet velocity vector orientation towards terrestrial gravitation vector «g» (orientability – like) the basic characteristics of the flame evolution depending on a jet velocity are sharply differed from two previous cases. The range of existence of the «bottleneck» flame area is reduced, flame detachment occurs in absence of the «bottleneck» flame area and finally ending of the microjet combustion occurs at the much greater jet velocity.
Acquiring The Pulsation Characteristics Of An Unsteady Vortex Flow With The Aid Of Pressure Probes
Authors: Mitryakov Andrey , Litvinov Ivan , Shtork Sergey
Published: December 2021

The special probes utilization together with measuring microphones allows to hold local measurements of pressure pulsations and to deform a flow structure marginally. Knowledge about a transfer function of the probe is required for the original signal reconstruction. This article presents the experimental technique of the probe transfer function obtainment. The theoretical assessment of the transfer function was carried out, using the model presented in the literature. Also the original signal reconstruction of pressure pulsations was carried out at the exit of the vortex tangential chamber.
Experimental Investigation Of Couple Precessing Vortex Ropes In A Hydraulic Vortex
Authors: Skripkin Sergey , Dremov Sergey , Shtork Sergey , Kabardin Ivan
Published: December 2021

The work is devoted to the experimental study of the interaction of the precessing vortex pair in the hydrodynamic vortex chamber. Swirling flow was created by a 12 tangentially directed rectangular nozzles. Design swirl number was varied in the range 0÷6.6 based on the geometry of the swirl device. The Reynolds number was varied in the range of 6 000÷52 000. Preliminary visual experiments has been conducted with changing output boundary conditions for controlling parameters of the vortex structure. It was found that stable mode with a double precessing structure is realized at full open outlet. Setting of diaphragm on the outlet of vortex chamber allows us to suppress the precession motion and significantly stabilize the flow. Further experiments included the quantitative measurement of the velocity distributions carried out using a laser Doppler anemometry (LDA).