NOPR Collection:

Interrelation between microphysical and optical properties of cloud and rainfall in the Indian region

2016-07-20T05:26:53Z

Title: Interrelation between microphysical and optical properties of cloud and rainfall in the Indian region Authors: Chakraborty, Swastika; Maitra, Animesh Abstract: Ground and satellite based measurements of microphysical and optical parameters of cloud are analysed for three tropical locations Kolkata, Guwahati and Bangalore during the year 2006 to find an interrelation between cloud optical depth, cloud effective radius, cloud liquid water content and rain. The present study suggests that a relation exists between cloud effective radius and cloud liquid water content. A minimum threshold of cloud optical depth is required for the precipitation to initiate. However, the threshold value depends on weather conditions of the tropical location. Cloud droplets with effective radii above 8 micron are mostly effective for the rain formation. Again, a threshold value of 5 is obtained for cloud optical depth for precipitation formation. There also exists a positive relation of accumulated rainfall with cloud effective radius and cloud optical depth as observed at a particular location. Page(s): 105-112

Magnetospherically reflected (MR) whistlers observed in DEMETER satellite and on the ground observation of normal whistlers at low latitudes

2016-07-20T05:25:50Z

Title: Magnetospherically reflected (MR) whistlers observed in DEMETER satellite and on the ground observation of normal whistlers at low latitudes Authors: Pandey, Uma; Chauhan, Vishal; Singh, Birbal Abstract: The DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite data have been analysed for a period of three and half months from 01 September to 16 December 2010 in search of whistlers and VLF emissions and their ground observations at low latitudes. The quick look data show intense sporadic bursts mostly in the Instrument Champ Electrique (ICE) channel of the satellite. These bursts are analysed using MATLAB software for the nighttime passes of upgoing orbits in the latitude range 20°-50°. The analysis shows records of large number of first component of magnetospherically reflected (MR) whistlers, mostly when the satellite is in low latitude ionosphere. These whistlers, together with normal whistlers observed in the satellite, are not observed on the ground as revealed by simultaneous ground observations at low latitude station Agra. This confirms them to be non-ducted whistlers which are reflected and observed in the ionosphere and magnetosphere. These MR whistlers are suggested to be the major source of slot formation between the two radiation belts. Page(s): 97-104

Investigation into quiet and magnetic storms periods above Magadan during October - December 2003

2016-07-20T05:22:26Z

Title: Investigation into quiet and magnetic storms periods above Magadan during October - December 2003 Authors: David, T W Abstract: The present work investigated the ionospheric response of the latitude above Magadan to the geomagnetic storms during October - December 2003. The study was based on storm time disturbance index, Dst, and the corresponding foF2 data above the ionosphere of Magadan in the East Asian sector. The response was investigated at all classes of storm and the quiet period inclusive. The analysis of the foF2 data during October - December 2003 shows that Dst of low magnitude can cause intense ionospheric storm. Dst values > -30 nT, which has been generally accepted to be quiet period caused major ionospheric storms of the order of 65% depletion and 59% enhancement in October. Also, two weeks before the commencement of the very intense geomagnetic storm on 20 November 2003 (Dst < -422 nT), quiet period (Dst > -30 nT) caused major ionospheric storms of the order of 70% enhancement and 45% depletion. December that was predominantly quiet, the weak Dst produced intense ionospheric storms of the order of 76% enhancement and 70% depletion. It is worthy to note that the peak positive Dst on 20 December 2003 between 06:00 and 09:00 hrs UT caused an intense ionospheric depletion above the ionosphere of Magadan with a peak value of ~70%. Page(s): 89-96

Comparison of observed h_mF2 and IRI 2007 model with M(3000)F2 estimation of h_mF2 during high solar activity for an equatorial station

2016-07-20T05:24:46Z

Title: Comparison of observed h_mF2 and IRI 2007 model with M(3000)F2 estimation of h_mF2 during high solar activity for an equatorial station Authors: Ehinlafa, O E; Adeniyi, J O Abstract: In this paper, the ways of improving the equatorial F2 layer peak heights estimated from M(3000)F2 ionosonde data measured using the Ionospheric Prediction Service (IPS-42) sounder at Ouagadougou, Burkina Faso (geog lat +12.4°N, geog long +1.5°W, magnetic dip +5.9°N) during high solar activity year (1991) was investigated. For this purpose, the observed height of maximum electron density of F2 region (h_mF2_obs), deduced using an algorithm from scaled virtual heights of quiet day ionograms; and the predicted h_mF2 values, which is given by the IRI 2007 model (h_mF2_IRI2007) have been compared with the ionosonde measured M(3000)F2 estimation of the h_mF2 values (h_mF2_est), respectively. A strong correlation with its coefficients R² for all the seasons ranging 0.562 - 0.857 for h_mF2_obs values, and ranging 0.876 - 0.968 for the h_mF2_IRI2007values was observed in the linear regressions of h_mF2_obs and h_mF2_IRI2007 with M(3000)F2 inverse. During the nighttime, estimated h_mF2 (h_mF2_est) was found to be positively correlated with the h_mF2_obsvalues by the post-sunset peak representation, which is not represented by the h_mF2_IRI2007values. Also, the validity of the h_mF2_estvalues has been investigated by finding the percentage deviations when compared with the h_mF2_obs and h_mF2_IRI2007. Page(s): 82-88

NOPR Collection:

Interrelation between microphysical and optical properties of cloud and rainfall in the Indian region

Magnetospherically reflected (MR) whistlers observed in DEMETER satellite and on the ground observation of normal whistlers at low latitudes

Investigation into quiet and magnetic storms periods above Magadan during October - December 2003

Comparison of observed hmF2 and IRI 2007 model with M(3000)F2 estimation of hmF2 during high solar activity for an equatorial station

Comparison of observed h_mF2 and IRI 2007 model with M(3000)F2 estimation of h_mF2 during high solar activity for an equatorial station