NOPR Community:http://nopr.niscpr.res.in/handle/123456789/560882026-10-09T23:19:40Z2026-10-09T23:19:40ZScaling of heavy rainy days with upper air profiles over Chennai during Northeast monsoonSingh, AlvinThakur, Manoj KumarGeesupalli, PurnadurgaAnandan, Naga RajeshKumar, T V LakshmiSharma, SomKumar, Prashanthttp://nopr.niscpr.res.in/handle/123456789/576652021-10-12T10:28:41Z2020-12-01T00:00:00ZTitle: Scaling of heavy rainy days with upper air profiles over Chennai during Northeast monsoon
Authors: Singh, Alvin; Thakur, Manoj Kumar; Geesupalli, Purnadurga; Anandan, Naga Rajesh; Kumar, T V Lakshmi; Sharma, Som; Kumar, Prashant
Abstract: This study aims to scale the heavy rainy days (rainfall > 64 mm per day) with the surface and upper-air parameters over Chennai (12.80° N and 80.03° E), located on the east coast of India, during the Northeast (NE) monsoon (October to December) from 2001 to 2015. The daily rainfall and radiosonde observations that are available from India Meteorological Department (IMD), Outgoing Long-wave Radiation (OLR) from Very High Resolution Radiometer (VHRR) Kalpana-1 Indian satellite, and Total Column Liquid Water (TCLW) and vertical velocity from ERA-Interimre analysis are used. The study commences with the comparison of mean daily Integrated Water Vapor (IWV) and rainfall over Chennai. Further, the study proceeds ahead by analyzing the IWV, TCLW, Instantaneous Condensation Rate (ICR) and precipitation extreme efficiency during the heavy rainy days. The results are such as (i) the heavy rainy days are better scaled using IWV and TCLW than with surface air temperature and OLR (ii) ICR during the all heavy rainfall days found high at 700 mb level, and (iii) the precipitation extreme efficiency which is estimated using the ratio of precipitation extreme (obtained from vertical velocity, specific humidity gradient) and the ICR has shown a linear relationship with the surface reaching rainfall through the temporal and spatial smearing of raindrops expected.
Page(s): 153-1612020-12-01T00:00:00ZIonospheric responses to the consecutive earthquakes over Canadian sectorKarthikeyan, EmperumalSrinivas, YasalaEmperumal, KaliappanSathishkumar, Sundararamanhttp://nopr.niscpr.res.in/handle/123456789/576642021-07-07T06:47:11Z2020-12-01T00:00:00ZTitle: Ionospheric responses to the consecutive earthquakes over Canadian sector
Authors: Karthikeyan, Emperumal; Srinivas, Yasala; Emperumal, Kaliappan; Sathishkumar, Sundararaman
Abstract: Recently, two successive earthquakes with the magnitude of 6.8 and 6.5 which have occurred at 200 km southwest of Port Hardy, Canada (49˚N, 129˚W) during October 2018 have been considered for our study. The TEC data has been acquired from nearby stations of these two events. It has been observed that an increase in TEC anomalies of about
0.1 TECU of moderate earthquake events occurred on the geo-magnetically quiet days. Besides, increases in the TEC anomalies have shown wave-like structures in the ionosphere and it may have associated with acoustic waves generated by earthquakes. The faulting mechanism of the earthquake and the propagation velocity of waves by TEC have confirmed the presence of acoustic wave activity.
Page(s): 162-1702020-12-01T00:00:00ZLow latitude ionospheric variations during geomagnetic storms measured using ROCSAT-1 satellite observationsRana, GeetaBardhan, AnannaSharma, Dinesh KumarYadav, ManiKanthttp://nopr.niscpr.res.in/handle/123456789/576622021-07-07T06:42:37Z2020-12-01T00:00:00ZTitle: Low latitude ionospheric variations during geomagnetic storms measured using ROCSAT-1 satellite observations
Authors: Rana, Geeta; Bardhan, Ananna; Sharma, Dinesh Kumar; Yadav, ManiKant
Abstract: In the present paper the response of ionospheric parameters- ion densities and ion temperature (H+, O+ and Ti) to a weak (30 July 1999) and a moderate (13 November 1999) geomagnetic storm (GS) at low latitude Indian region using observed and modelled values has been analyzed. The study has been carried out by using ROCSAT-1 satellite data over the region encompassed between 5-35º geog N and 65-95º geog E at an average altitude ~ 600 km. A comparative study has also been done with the IRI-2016 modelled values. The ionospheric plasma parameters have shown anomalous behaviour during disturbed days in comparison to the quiet days. For the weak GS, both the average O+ and H+ density have been increased by a factor of around 1.8 during disturbed and quiet days respectively as calculated by ROCSAT-1. For the moderate GS, the average O+ and H+ density has been increased by a factor of around 2.7 and 6.3 respectively during disturbed and quiet days respectively, as calculated by ROCSAT-1. And the least or negligible variation has been observed in Ti for both measured and modelled values during weak and moderate GS.
Page(s): 171-1792020-12-01T00:00:00ZVariability of NmF2 and its correlation with solar and geomagnetic variations at an equatorial station in the African sectorKazeem, Abdullahi KikelomoOlawepo, Adeniji OlayinkaRabiu, Akeem Babatundehttp://nopr.niscpr.res.in/handle/123456789/576612021-07-07T06:38:12Z2020-12-01T00:00:00ZTitle: Variability of NmF2 and its correlation with solar and geomagnetic variations at an equatorial station in the African sector
Authors: Kazeem, Abdullahi Kikelomo; Olawepo, Adeniji Olayinka; Rabiu, Akeem Babatunde
Abstract: This study focuses on the variability of NmF2 and the impact of the solar and geomagnetic activity on the variability of NmF2 over Ouagadougou, an equatorial ionisation anomaly station in the African sector. The daily hourly values of the critical frequency (foF2) covering two different solar cycles are used to study the variability of NmF2. The solar and geomagnetic data are used to examine their effect on the variability of NmF2. The results show that NmF2 displays obvious diurnal, seasonal and solar cycle effects. The semi-annual variation, winter and annual anomalies of NmF2 are clearly seen at all levels of solar activities. There is equinoctial asymmetry in NmF2. NmF2 is also characterized by two peaks namely pre-noon and post-noon peaks and noontime bite-out. The SSN is observed to have major effects on the variability of NmF2.
Page(s): 180-1962020-12-01T00:00:00Z