Final Report on UGC- MRP

Transcription

1 Final Report on UGC- MRP [F.NO /2011 (SR)] Entitled Study of low latitude total electron content (TEC) during the rising phase of solar cycle 24 By Dr. Rajesh Pandey Professor Department of Physics Mohanlal Sukhadia University Udaipur NAAC Accredited A Grade University July 2014

2 Annexure - III UNIVERSITY GRANTS COMMISSION BAHADUR SHAH ZAFAR MARG NEW DELHI STATEMENT OF EXPENDITURE IN RESPECT OF MAJOR RESEARCH PROJECT 1 Name of Principal Investigator: Dr. Rajesh Pandey 2 Department of University: Department of Physics, Mohanlal Sukhadia University Udaipur 3 UGC approval No. and Date: F /2011(SR) Dated 30 June Title of the Research Project: Study of low latitude total electron content (TEC) during the rising phase of solar cycle 24 5 Effective date of starting the project: 01 July a. Period of Expenditure: From 01 July 2011 to 30 June 2014 b. Details of Expenditure S.No. Item Amount Approved Rs. Expenditure Incurred Rs. i. Books & Journals Nil Nil ii. Equipment (please enclose the quotation) 60,000 59,997 iii. Contingency 81,000 81,000 iv. Field Work/Travel (Give details in the proforma at Annexure- VI). 1,08,000 10,549 v. Hiring Services Nil Nil vi. Chemicals & Glassware/Consumables 27,000 27,000 vii. Overhead 40,800 40,800 viii. Any other items (Please specify) None None

3 c. Staff Date of appointment: 15 September 2011 to 30 June 2014 S.No. Item From To Amount Approved (Rs.) 1 Project Fellow salary (Non-GATE/ Rs.14, 000/- p.m. *Rs. 16,000/-p.m * Expenditure Incurred(Rs.) 4,39,680 4,39,501 *The salary to the project fellow could be paid only up to 29 March 2014 as per the amount sanctioned by the UGC 1 It is certified that the appointment(s) have been made in accordance with the terms and conditions laid down by the Commission. 2 It as a result of check or audit objection, some irregularly is noticed, later date, action will be taken to refund, adjust or regularize the objected amounts. 3 revised rates shall be made with arrears on the availability of additional funds. 4 It is certified that the grant of Rs. 7,56,480/-(Rupees Seven Lac Fifty Six Thousand Four Hundred Eighty only) received from the University Grants Commission under the scheme of support for Major Research Project entitled Study of low latitude total electron content (TEC) during the rising phase of solar cycle 24 vide UGC letter No. F /2011(SR) Dated 30 June 2011 has been fully utilized for the purpose for which it was sanctioned and in accordance with the terms and conditions laid down by the University Grants Commission. SIGNATURE OF PRINCIPAL INVESTIGATOR REGISTRAR SIGNATURE OF THE CO INVESTIGATOR

4 Annexure - IV UNIVERSITY GRANTS COMMISSION BAHADUR SHAH ZAFAR MARG NEW DELHI STATEMENT OF EXPENDITURE INCURRED ON FIELD WORK Name of the Principal Investigator: Dr. Rajesh Pandey Name of the Place visited Duration of the Visit Mode of Journey Expenditure Incurred (Rs.) 1. Infra-red Observatory PRL, Mount Abu From To to Road Rs UGC-New Delhi to Rail Rs Dibrugarh University, Assam to Rail Rs UGC-New Delhi to Rail Rs Certified that the above expenditure is in accordance with the UGC norms for Major Research Projects. SIGNATURE OF PRINCIPAL INVESTIGATOR REGISTRAR SIGNATURE OF THE CO-INVESTIGATOR

5 Annexure IX UNIVERSITY GRANTS COMMISSION BAHADUR SHAH ZAFAR MARGNEW DELHI PROFORMA FOR SUBMISSION OF INFORMATION AT THE TIME OF SENDING THE FINAL REPORT OF THE WORK DONE ON THE PROJECT 1 NAME AND ADDRESS OF THE PRINCIPAL INVESTIGATOR Dr. Rajesh Pandey, Professor Department of Physics University College of Science Mohanlal Sukhadia University Udaipur NAME AND ADDRESS OF THE INSTITUTION Department of Physics, University College of Science Mohanlal Sukhadia University, Udaipur UGC APPROVAL NO. AND DATE F.NO /2011 (SR) Dated 30 June DATE OF IMPLEMENTATION 01 July TENURE OF THE PROJECT Three Years (01 July 2011 to 30 June 2014) 6 TOTAL GRANT ALLOCATED Rs. 8,29,333/- [Eight Lac Twenty Nine Thousand Three Hundred Thirty Three Only] 7 TOTAL GRANT RECEIVED Rs. 7,56,480/- [Seven Lac Fifty Six Thousand Four Hundred Eighty Only] 8 FINAL EXPENDITURE 6,58,847/- [Six Lac Fifty Eight Thousand Eight Hundred Forty Seven Only] 9 TITLE OF THE PROJECT Study of low latitude total electron content (TEC) during the rising phase of solar cycle OBJECTIVES OF THE PROJECT It is a known fact that the ionospheric variability, arising due to the equatorial fountain effect in the anomaly zone latitudes, or due to the ESF; or due to the geomagnetic storms following the coronal mass ejection from the sun jeopardizes the GPS based satellite navigation, ground positioning and communication. Hence conscious efforts are needed to reduce the extent of damage that these events may

6 cause. For this, study of the effect of these events on the GPS derived Total Electron Content and the ionospheric scintillations that these events may produce, is necessary. Thus the main aims of the proposed study are (A) To study the ionospheric variability in terms of total electron content over the Indian low latitude ionosphere during the rising phase of solar cycle 24 conditions. (B) To study the impact of geomagnetic storms on the TEC from multiple stations (C) To study the equatorial spread F events in terms of TEC variations. 11 WHETHER OBJECTIVES WERE ACHIEVED Yes. All the objectives that were set have been achieved. For this purpose six different studies were undertaken. Details of those studies are given here-under. Study no. 1: A comparative study on the variation of total electron content (TEC) was performed using the observations from two GPS receivers located at magnetically conjugate stations near the equatorial ionization anomaly crests: Udaipur, India in the northern hemisphere and Diego Garcia in the southern hemisphere, located at approximately same geographic longitude. Our study reveals that the TECs at both stations shows the semi-annual variability being higher in equinoxes than in solstices. An important finding of the work is that in the northern hemisphere, during the declining phase of solar cycle 23, the amplitude of the winter crest is smaller than that in the summer whereas it is found to be comparable/higher (which is normally termed as winter anomaly in the mid latitudes) during the rising phase of solar cycle 24. Thus it is concluded that the so called winter anomaly at low latitudes is a phenomenon totally different from the one observed at mid latitudes. In fact its manifestation at low latitudes can be accounted for in terms of variation of the solar flux and/or the strength of the equatorial electrojet during different seasons. This work has been published in the Journal of atmospheric and solar terrestrial Physics, published by the Elsevier, England. Details of the publication are as follows: S. S. Rao, P. Galav, Shweta Sharma and R. Pandey, Low-latitude TEC variability studied from magnetically conjugate locations along 73 E longitude, Journal of Atmospheric and Solar Terrestrial Physics, 104, 1-6, 2013 doi: /j.jstp Study no. 2: This study was aimed to investigate winter anomaly phenomena in TEC. Results of the Study-1 suggest that the seasonal variation in TEC at low latitudes could not possibly be viewed as the presence or absence of the winter anomaly. Since this conclusion was based upon the TEC observation along 73º longitude only, in order to generalize these conclusions observations from other longitude sectors became necessary. Thus, an in-depth study of TEC variability at nearly same geomagnetic latitude (~ 15 N) in different longitudes and regions is called for. Therefore, the phenomenon of the winter anomaly at two more stations, namely

7 KUNM, located along 102 E longitude in Chinese region and TWTF, located along 120 E longitude in Taiwanese zone, besides Udaipur in the Indian zone were studied. In addition to these three low latitude stations, TEC variation for the same period, years at two mid latitude stations, namely, POL2 and IRKT has also been studied. The main motive behind the study of mid latitude TEC is to ascertain the presence of the winter anomaly in TEC at mid latitudes during different levels of solar activity. Thus the present study is devoted to investigate seasonal variation in TEC at low latitudes vis-à-vis mid latitudes. Study no. 3: The results of TEC variability over low latitudes vis-à-vis that over mid latitudes have compelled to look for variation in mid latitude fof 2 during various phases of solar activity. After all, the term winter anomaly was coined for anomalous seasonal variation in NmF 2. Thus, as a final step the variation of fof 2 and hmf 2 at mid latitude station, Novosibirsk (Geog. Lat N, Geog. Long E, Geomag. Lat N) has been studied. Ionosonde data of a mid latitude station Novosibirsk (Geog. Lat N, Geog. Long E) has been analyzed for the years that covers the major part of solar cycle 23. Our results show the presence of winter anomaly in the daytime F2 layer critical frequency during different phases of solar activity. Results also reveal a semiannual variation of fof 2 with two maxima and a minimum that always appears in summer. While the first maximum is in the spring equinox, the second one is found to shift from autumn to winter with the increase of solar activity. The maximum height of F2 layer during the daytime shows variation as per the solar activity. It is higher during the higher activity periods and lower during the periods of low activity. Results of ionosonde observations have been compared with those obtained from IRI-2007 model and it is found that model reproduces gross features of fof 2 variation. However, the modeled hmf 2 variations during equinoxes are significantly different from the ones derived using the ionosonde data. The model also under estimates the hmf2 values. This work has been published in the Advances in Space Research, published by the Elsevier. Details of the publication are as follows: S. S. Rao, Shweta Sharma, P. Galav and R. Pandey, Variation of monthly mean fof 2 and hmf 2 over a mid latitude station during the period , Advance in Space Research, 53, , 2014, DOI: /j.asr Study no. 4: During very intense geomagnetic storm of November 7-8, 2004 simultaneous presence of storm time disturbance dynamo and eastward and westward directed prompt penetration electric fields inferred from the ground based magnetometer data in the 75 E sector is presented. Magnetometer observations show that, on the whole, average H variation on 8 November remains below the night time level compared to its quiet day variation. A number of upward and downward excursions have been observed between 0130 UT and 0800 UT in the H variation on 8 November. These excursions in H have been attributed to the episodes of eastward and westward prompt penetrating electric fields. Ionospheric response in the equatorial ionization anomaly region along 75 E has also been studied using the total electron content data recorded at five GPS stations, namely Udaipur, Bengaluru (IISC), Hyderabad (HYDE), Maldives (MALD) and Diego

8 Garcia (DGAR). Observation of markedly suppressed EIA, in conjunction with H variation which was m negative during the daytime on 8 November, indicates the presence of an external field of opposite polarity (the disturbance dynamo electric field) that either undermined, or overshadowed the daytime ambient (eastward) electric field to the extent that the equatorial plasma fountain could not become effective. This work has been published in the Astrophysics and Space Science, published by the Springer- Science. Details of the publication are as follows: P. Galav, Shweta Sharma, S. S. Rao, B. Veenadhari, T. Nagatsuma and R. Pandey, Study of simultaneous presence of DD and PP electric fields during the geomagnetic storm of November 7-8, 2004 and resultant TEC variation over the Indian Region, Astrophysics and Space Science, Vol.350 (2), pp , 2014 DOI: /s Study no. 5: Observations of night time TEC depletions during the geomagnetically quiet as well as disturbed conditions were made. For the study of night time TEC depletions during the geomagnetically quiet conditions, the TEC data have been investigated for a low latitude station, UDPR, Udaipur (Geog. Lat N, Geog. Long E, Geomag. Lat N) located near the northern crest of EIA and a near equatorial station, IISC, Bengaluru (Geog. Lat N, Geog. Long E, Geomag. Lat N). For the study of night time TEC depletion during the disturbed geomagnetic conditions, the TEC data over the low latitude stations QUI1, Quito (Geog. Lat S, Geog. Long E, Geomag. Lat N) located in the Ecuador, South America have been analyzed for the event of 15 May 2005 geomagnetic storm. It is also realized that the observation of nighttime TEC depletions is not limited to the equatorial and low latitudes alone. Study no. 6: The ionospheric response to the geomagnetic storm of 15 May 2005 has been studied over mid latitude stations in the day and night side, simultaneously. In the day side the ionospheric response has been studied using the ground based GPS and ionosonde measurements from the stations POL2 and Alma-Ata respectively. The day side TEC andfof 2 variations are characterized by two well separated enhancements. Of which the first enhancement in both the parameters is attributed to the episode of prompt penetration electric field caused by the sudden southward turning of IMF Bz around 0600 UT. The second enhancement which was also superposed by wave like modulations has been attributed to the storm induced winds. The maximum peak-to-peak amplitude of modulation in TEC is found to be 5 TECU. The enhanced plasma density observed during the daytime at mid latitudes is found to be locally produced, and not transported from the equatorial ionization anomaly region because the time of enhanced plasma density at mid latitude is earlier than that observed at low latitudes. During the storm main phase, the night side GPS observations from the mid latitude station ALGO show moderate to large TEC fluctuations and short duration depletions that occur in a narrow latitude zone. These fluctuations and depletions in TEC have been attributed to the combined effect of storm induced equatorward movement of the mid latitude ionospheric trough due to the expansion of auroral oval and the storm time enhanced density. The maximum amplitude of the TEC depletions is found to be of the order of 20

9 TECU. Rate of TEC Index, ROTI is also found to be high and its maximum value was 2. This work has been published in the Journal of Geophysical Research, published by the American Geophysical Union. Details of the publication are as follows: Praveen Galav, Sardar Rao, Shweta Sharma, Galina Gordiyenko and R. Pandey, Ionospheric response to the geomagnetic storm of 15 May 2005 over mid latitudes in the day and night sectors simultaneously, Journal of Geophysical Research, Volume 119, , 2014, DOI: /2013JA ACHIEVEMENTS FROM THE PROJECT The project work has been very useful for establishing and ascertaining the suitability of individual as well as regional network of GPS receivers for the study of ionospheric phenomena in quiet as well as disturbed ionospheric conditions. During the quiet solar conditions, with varying solar flux during different phases of solar cycle, the study has brought out an altogether new concept with regard to the low latitude winter anomaly in TEC. The study has been very useful in highlighting impact of different geomagnetic storms that occurred during different local times on the ionospheric TEC. A new finding has been the existence of disturbance dynamo electric fields even in the presence of storm time prompt penetration electric fields during the storm of November Yet another finding on storm time electric fields has been their profound impact on the low as well as mid latitude ionosphere that was brought out during the study of the storm of May, Further, it was shown that the mechanisms and the effects of storm time electric fields in the day and night sectors were profoundly different. Study of depletions in the nighttime TEC arising due to the phenomenon of equatorial spread F have shown that the extent and lifetime of depletions is varied on different nights. The depletions are observed during quiet periods as well as during the disturbed periods. Since sudden and large variations in TEC arising during the geomagnetic storms or due to the equatorial spread F are detriments to the satellite based navigation and ground positioning, the present studies would help in assessing the extent of damage these phenomena may cause and would compel the model developers to improve upon the existing models, and system engineers to set the range-error margins to mitigate the degradation of the received signal caused by these phenomena. 13 SUMMARY OF THE FINDINGS This project study is concerned with variation of low latitude ionospheric total electron content (TEC) during different phases of solar activity. For this the TEC data for the period has been used. This period encompasses the moderate, low and rising phase of solar activity. Thus the long term study of low latitude TEC variation during different phases of solar activity has been done. For a comparative study, the mid latitude TEC and ionosonde data have also been used wherever it was necessary. Besides the long term study of TEC variation during different phases of solar activity, the studies of TEC variation during geomagnetic storms and the night time TEC depletions have been made. A summary of the present study is as follows:

10 1. The overall trend of variation of GPS-TEC at low as well as mid latitudes follow the trend of solar flux, its value decreased with the declining phase of solar cycle-23 and became lowest during the years , thereafter it again increased with the increasing phase of solar cycle-24. The only difference is regarding the value of TEC. It is found smaller at mid latitudes compared to low latitudes. This may be partly attributed to the additional ionization at low latitudes due to the so called fountain effect. 2. GPS-TEC over low as well as mid latitudes show the semi-annual oscillation throughout the period wherein two well separated maxima occurred during the vernal and autumn equinoxes respectively. At low latitudes, both maxima were well developed throughout the period whereas at mid latitudes the occurrence of first maxima is consistently observed throughout the period but second maxima seems to have disappeared in the years 2007 and Ionosonde Observations also reveal a semiannual oscillation in fof 2 over mid-latitude with minima during the summer. The first maximum always appears in the spring equinox but the appearance of the second one is linked with the solar activity. During the low solar activity it appears in autumn but it shifts to winter in high activity years. 3. Winter anomaly is a mid latitude phenomenon that has a well established mechanism for its formation. Thus, the seasonal variation in TEC at low latitudes could not possibly be viewed as the presence or absence of the winter anomaly. This is because the TEC variability in the EIA zone has totally different underlying physical processes than the ones at the mid latitudes. Thus, the winter anomaly in the EIA zones, as reported earlier by a number of workers for particular longitudes, is a misnomer and is not a phenomenon of any particular significance and relevance for the EIA zone. In fact, what has been termed as the winter anomaly in the EIA zone is merely seasonal variability of the crest TEC which is intimately dependent on the (a) solar flux during the course of a year and (b) strength of the equatorial electrojet during different seasons of a year. This implies that, compared to summer when any of the contributors (or both) is (are) high during winter then the winter crest TEC would be higher than during the summer in the EIA zone. 4. Further the observations of the low latitude stations located along 73º E, 102º E and 120º E show the absence of the so called winter anomaly feature throughout the period Its subdued appearance in the years , a clear cut presence during the year 2011 and its total disappearance again in the year 2012 confirms that the feature of higher TEC values during December solstice compared to the June solstice at low latitudes is not a consistent feature. Even in the high solar activity (years 2011 and 2012) it appeared only when the level of solar flux was significantly high during December solstice. 5. Seasonal variation in TEC at low and mid latitudes is similar. Similar to low latitudes TEC, at mid latitude also the feature of winter anomaly appeared only when the level of solar flux was significantly high during December solstice compared to its level in June solstice. 6. Compared to GPS-TEC at low as well mid latitudes, the ionosonde observations at the mid latitude station Novosibirsk show that the winter anomaly in fof 2 is a consistent feature with passage of different phases of solar activity. Thus, its appearance in fof 2 is independent of the solar activity whereas in TEC it strongly depends upon the level of solar flux during solstices for a given year. These results

11 strongly suggested that the feature of winter anomaly in TEC over low as well as mid latitude is not a phenomenon of any particular significance and relevance. 7. The overall variation of GPS and IRI modeled TEC is found to be similar but there are two notable dissimilarities. Firstly, the IRI model underestimates the TEC values. Secondly, the IRI model fails to reproduce results of GPS-TEC observations at low as well as at mid latitudes during the solstices for the year The IRI model reproduces gross features of fof 2 variation for the period , yet there are differences in detail. In particular, the model underestimates the fof 2 values. However, the modeled hmf 2 variations during equinoxes are significantly different from the ones derived using the ionosonde data. The model also under estimates the hmf 2 values. 8. The geomagnetic storm of 7-8 November 2004 was an unusual space weather event wherein simultaneous presence of disturbance dynamo and prompt penetration electric fields over the Indian region has been shown. Existence of a DD field in the Indian sector stems from the fact that the geomagnetic conditions on the night of 7 November were disturbed as IMF B z and Ф PC were highly variable. In addition to these, the AE was also strong and disturbed. These conditions were conducive for the generation of the DD fields. Since daytime H IND was mostly below the nighttime zero level, it implied presence of a DD field (westward directed) during the daytime on 8 November. While the DD field was operative, short lived upward and downward excursions (with respect to the nighttime level) in H IND variation over the Indian region are also seen. These upward and downward excursions have been attributed to the eastward and westward prompt penetration electric fields. Thus, simultaneous presence of DD and PP fields is shown. Ionospheric variation in terms of TEC on 8 November along 75 E longitude sector on both sides of the geomagnetic equator shows completely diminished EIA. Since the EIA was altogether absent along the 75 E longitude sector, it indicated the presence of an external field of opposite polarity (the disturbance dynamo electric field) that either undermined, or overshadowed the daytime ambient eastward field. Hence the equatorial plasma fountain was not effective. 9. The study of response of TEC during geomagnetic storm of 15 May 2005 in the day side ionosphere over the stations extending from equator to mid latitude along Indian longitude range has been done. For the day sector ionosonde observations over mid latitude have been used additionally. Main conclusions of the work are: The day side TEC variation is characterized by two well separated enhancements. The first enhancement is attributed to the PP electric field which is responsible for the local uplifting of the plasma under the E x B drift. The second enhancement is broad and much larger than the first one, and is superposed by modulations. The enhancement and modulations thereon have been attributed to storm induced equatorward neutral winds 10. Observance of depletion north of Udaipur (beyond 15 N) on 31 March 2012 suggests that the plasma bubble that produced depletion must have risen to a very high height over the equator so that the connecting field line had a foot in the ionospheric region which was much above the geographic location of Udaipur. Also the observation of PRN 17 on 31 March 2012 suggests that one may be observing the same depletion, first from IISC and later from Udaipur. Further, the longitudinal separation between the two stations may also be used to infer the north-west drift of the bubble that produced this depletion.

12 11. Observation of TEC variation on 10 March 2013 implies that the plasma bubble that produced depletions may have sustained for at least an hour at the same location. Such a case is being reported for the first time. 12. Depletions in TEC during geomagnetically quiet time are seen mostly in the equinoxes and increases with increase in solar activity. 13. Night time TEC observations during the geomagnetic storm of 15 May 2005 over QUI1 may be used to infer that the nighttime TEC depletions at low latitudes could be observed before the storm main phase. 14. Enhanced level of TEC compared to the mean quiet day in the night side at mid latitude is also observed and is signature of the storm enhanced density. 15. The night side ionospheric response of 15 May 2005 geomagnetic storm event over mid latitude reveals moderate to very large fluctuations and depletions in TEC during the main phase of storm, and have been attributed to the combined effect of storm induced equatorward movement of the mid latitude ionospheric trough due to the expansion of auroral oval and the storm time enhanced density. 14 CONTRIBUTION TO THE SOCIETY ( GIVE DETAILS ) The degradation of GPS signals caused by the disturbed ionospheric conditions arising either due to the equatorial spread F or due to the space weather events has been brought out by this project study. Since in the current era the society is heavily dependent on the satellite based communication, navigation and ground positioning which is facilitated by the GPS system, whose signals have to pass through the ionosphere before reception on the ground, the present study would help in assessing the impact of disturbed ionospheric conditions on satellite signals. 15 WHETHER ANY PH.D. ENROLLED/PRODUCED OUT OF THE PROJECT Yes, the Project Fellow, Mr. Sardar Singh Rao, was also enrolled as a Ph.D. student. He has worked on the topics and problems that have been studied under this project and has submitted the Ph.D. thesis during June NO. OF PUBLICATIONS OUT OF THE PROJECT ( PLEASE ATTACH RE-PRINTS) No. of publications: 04 (Re-prints of the Research Papers are attached with this report) (PRINCIPAL INVESTIGATOR) (REGISTRAR) (CO-INVESTIGATOR)