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Case study of ISWI in Vietnam : A comparison of ionospheric parameters observed over Ho Chi Minh with IRI predictions
| Content Provider | Semantic Scholar |
|---|---|
| Author | Lan, Hoàng Thái |
| Copyright Year | 2013 |
| Abstract | For the contribution of Vietnam to ISWI activities, there are 3 GPS receivers, 3 Ionosondes, 1 AWESOME and 1 MAGDAS operating in Vietnam. With a special geographical position stretching from the north tropic to the magnetic equator, Vietnam is an interesting area to supplement the data for the Global Space Weather Model. The Ionosphere is an important indicator of Space Weather and the International Reference Ionosphere (IRI) model has become widely accepted. The first task of ionospheric science in a new location is often comparing the observed data with IRI. This paper presents the results of comparisons of the foF2 and TEC observed over Ho Chi Minh City (10.51 N, 106.33 E) with the values calculated according to the IRI-2007 in order to evaluate the applicability of the model in forecasting for the equatorial region of Vietnam. We compare the critical frequency of layer F (foF2) and Total Electron Content (TEC) values for two phases of solar activity. The results show very good diurnal correlations between the observed foF2 and TEC with IRI values in the decreasing solar activity period 2003 – 2006 (the deviation < 15%). In the increasing period 2009 – 2012, good correlation was in the morning time before the foF2 peak at about 10 LT, with a deviation about 10% (except 2012). However, after 10 LT, the IRI-foF2 values rose up and the deviations were about 25% to 30%, especially during evening. In the years with low solar activity (SSN < 40), the IRI-foF2 are almost always higher than the observed foF2 data and vice versa for the years with SSN > 40. This is a note for correction IRI model applying for Vietnam. The comparison of the TEC shows that the correlation between GPS-TEC and IRI-TEC generally was good with coefficients k > 0.8 and R > 0.9 for the period 2006 2010. The worst relationship were March, April, September, October, November and December 2011, corresponding to periods when the TEC gradients are highest. The phenomenon of decline in the TEC at noon over Ho Chi Minh City observed pretty weak. This phenomenon appeared only in a few months from April to September, when the ionization is high. In the period from 0 to 5 am local time, the average minimum GPS-TEC observed over Ho Chi Minh City is about 3 tecu, while the IRI-TEC value is ~ 0.3. Thus, the IRI-TEC values should be recalibrated. © 2014 BBSCS RN SWS. All rights reserved |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://newserver.stil.bas.bg/SUNGEO/00SGArhiv/SG_v9_No1_2014-pp-63-70.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
