Response of the EIA ionosphere to the 7-8 May 2005 geomagnetic storm

In this paper, response of low latitude ionosphere to a moderate geomagnetic storm of 7–8 May 2005 (SSC: 1920 UT on 7 May with Sym-H minimum, ∼−112 nT around 1600 UT on 8 May) has been investigated using the GPS measurements from a near EIA crest region, Rajkot (Geog. 22.29°N, 70.74°E, Geomag.14°), India. We found a decrease in total electron content (TEC) in 12 h after the onset of the storm, an increase during and after 6 h of Sym-H deep minimum with a decrease below its usual-day level on the second day during the recovery phase of the storm. On 8 May, an increase of TEC is observed after sunset and during post-midnight hours (maximum up to 170%) with the formation of ionospheric plasma bubbles followed by a nearly simultaneous onset of scintillations at L-band frequencies following the time of rapid decrease in Sym-H index (−30 nT/h around 1300 UT).     

Day-to-day variability of equatorial anomaly in GPS-TEC during low solar activity period

The ionospheric total electron content (TEC) in the northern hemispheric equatorial ionization anomaly (EIA) crest region is investigated by using dual-frequency signals of the Global Positioning System (GPS) acquired from Rajkot (Geog. Lat. 22.29°N, Geog. Long. 70.74°E; Geom. Lat. 14.21°N, Geom. Long. 144.90°E), India. The day-to-day variability of EIA characteristics is examined during low solar activity period (F10.7∼83 sfu). It is found that the daily maximum TEC at EIA crest exhibits a day-to-day and strong semi-annual variability. The seasonal anomaly and equinoctial asymmetry in TEC at EIA is found non-existent and weaker, respectively. We found a moderate and positive correlation of daily magnitude of crest, Ic with daily F10.7 and EUV fluxes with a correlation coefficient of 0.43 and 0.33, respectively indicating an existence of a short-term relation between TEC at EIA and the solar radiation even during low solar activity period. The correlation of daily Ic with Dst index is also moderate (r = −0.35), whereas no correlation is found with the daily Kp index (r = 0.14) respectively. We found that the magnitude of EIA crest is moderately correlated with solar flux in all seasons except winter where it is weakly related (0.27). The magnitude of EIA crest is also found highly related with EEJ strength in spring (r = 0.69) and summer (r = 0.65) than autumn (0.5) and winter (r = 0.47), though EEJ is stronger in autumn than spring.     

Comparative Utilization of Limited Energy for Continuous and Pulse Operations

Comparative utilization of a limited amount of energy for continuous and pulse operations was investigated. Under a restriction that the amount of available energy was limited, general equations for operational hours of the energy source for given power output were derived for both continuous and pulse mode operations. This paper points out that due to various adjustable parameters available for pulse mode operation, if properly designed pulse mode operation produces longer utilization of available energy for required output power than continuous mode operation.     

Gender diversity in geo-spatial technology and applications disciplines uptake in developing Asian countries – A survey-based competency analysis

Geo-Spatial Technology and Applications (GSTA) contributes significantly to the implementation of the UN 2030 Agenda for Sustainable Development, which seeks to ‘leave no one behind’. This study attempts to assess the gender diversity in enrolment in GSTA programmes in developing countries in Asia using data available with the UN-affiliated Regional Centre in India. A survey was also conducted to gauge trainees’ comfort in a complex multi-cultural, multi-linguistic classroom environment. The analysis shows that female participation in short-term courses has been increasing rather steeply over the years (1995–2019). The enrolment has reached 30% in recent years. It is also observed that the female participants have preferred (about 10%) to enrol in physical Science and Technology (ST) -oriented courses such as Remote Sensing and GIS, Satellite Meteorology and Climate Change, and Space and Atmospheric Sciences when compared to electrical Engineering and Technology-oriented Satellite Communications and Global Navigation Satellite Systems courses that would require a strong knowledge of digital signals and systems theory.The survey study with a participation of 150 trainees from 17 countries shows that women trainees have a slight edge by 9% over the male counterparts in learning ST elements of the courses. At sub-regional levels, it is observed that participants from Indian sub-continent countries (ISC) are better by 15% than participants from South-east Asian Countries (SAC) and Central Asian Countries (CAC). As far as the course structure perspective is concerned, there has been a significant difference with 70% of the ISC trainees have found the courses as well-balanced covering equally both technology and applications, while only 36% and 56% of the trainees from SAC and CAC, respectively, have found the course as balanced. Importantly, the survey has revealed that the participants from SAC and CAC have a big challenge in apprehending lectures in English, as reflected by their top scores at 18% and 17%, respectively, compared with the corresponding value of the ISC trainees being 72%. Recommendations are suggested to sustain the female enrolment in long-term GSTA training programmes. Strategies that create family-friendly learning conditions, including joint education programmes involving lead institutions of the participants’ countries, are proposed to facilitate higher female participation. Furthermore, measures such as standardisation of curricula regionally at undergraduate levels and having periodic meetings of trainers are recommended in order to minimise the trainees’ core competency gaps in GSTA disciplines at the regional level.     

Studies of electron and ion temperatures at 500 km altitude during sunrise using Indian SROSS C2 satellite

Solar dependence of electron and ion temperatures (T_e and T_i) in the ionosphere is studied using RPA data onboard SROSS C2 at an altitude of ∼500 km and 77°E longitude during early morning hours (04:00–07:00 LT) for three solar activities: solar minimum, moderate and maximum during winter, summer and equinox months in 10°S–20°N geomagnetic latitude. In winter the morning overshoot phenomenon is observed around 06:00 LT (T_e enhances to ∼4000 K) during low-solar activity and to T_e ∼ 3800 K, during higher solar activity. In summer, it is observed around 05:30 LT, but the rate of T_e enhancement is higher during moderate solar activity (∼2700 K/hr) than the low-solar activity (∼1700 K/hr). During equinox, this phenomenon is delayed and is observed around 06:00 LT (∼4200 K) during all three activities.     

TEC variability near northern EIA crest and comparison with IRI model

Monthly median values of hourly total electron content (TEC) is obtained with GPS at a station near northern anomaly crest, Rajkot (geog. 22.29°N, 70.74°E; geomag. 14.21°N, 144.9°E) to study the variability of low latitude ionospheric behavior during low solar activity period (April 2005 to March 2006). The TEC exhibit characteristic features like day-to-day variability, semiannual anomaly and noon bite out. The observed TEC is compared with latest International Reference Ionosphere (IRI) – 2007 model using options of topside electron density, NeQuick, IRI01-corr and IRI-2001 by using both URSI and CCIR coefficients. A good agreement of observed and predicted TEC is found during the daytime with underestimation at other times. The predicted TEC by NeQuick and IRI01-corr is closer to the observed TEC during the daytime whereas during nighttime and morning hours, IRI-2001 shows lesser discrepancy in all seasons by both URSI and CCIR coefficients.     

A Practical PRSD System for Multiple Target Detection

A block diagram of a practical system using the sequential detection technique for radar detection of multiple targets is given. The system is designed to obtain better detection probability with a lower value of signal-to-noise ratio for a given false-alarm probability and average transmitted power. The total pulse duration is divided into a number of range elements which are tested for the presence or absence of a target before switching the antenna beam to the next position.