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Реконструкция на електронните профили във външната йоносфера и плазмосфера

Реконструкция на електронните профили във външната йоносфера и плазмосфера. Иван Кутиев – ГФИ - БАН Пенчо Маринов – ИПОИ - БАН. Аналитични формули за Ne(h). sech-squared (Epstein) layer. exponential layer. Chapman layer. parabolic layer. Topside sounder Ne profiles.

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Реконструкция на електронните профили във външната йоносфера и плазмосфера

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  1. Реконструкция на електронните профили във външната йоносфера и плазмосфера Иван Кутиев – ГФИ - БАН Пенчо Маринов – ИПОИ - БАН

  2. Аналитични формули за Ne(h) sech-squared (Epstein) layer exponential layer Chapman layer parabolic layer

  3. Topside sounder Ne profiles The goal of the project was to produce Alouette-2, ISIS-1 and ISIS-2 digital topside ionograms from selected original 7-track analog telemetry tapes. More than ½ million digital topside ionograms are now available for downloading at ftp://nssdcftp.gsfc.nasa.gov. TOPside Ionogram Scaler with True-height (TOPIST) algorithm was developedto automatically scale digital ionograms

  4. Дефиницията на scale height иtransition height– ключ към използуването на огромната база данни на topside sounders O+ scale height = dh/d(lnNe)

  5. Definition of O+ scale height HT and transition height hT • The database, archived at the National Space Science Data Center (NSSDC), Greenbelt, MA, includes 176,622 topside electron density (Ne) profiles from the Alouette-1a, -1b, -1c and -2 and ISIS-1 and -2 topside sounders, covering the period 1962-1979. A detailed description of the database is given by Bilitza (2001).

  6. Database –O+ scale height HT • Imposed limits : (200-1500) km for hT, (0-600) km for HT. The database contained only pairs of hT and HT data. This reduced the total number of measured profiles with 3.7%. • The histograms of percentage distribution of HT values (left panel) and its longitude coverage. The most likely HT value is around 100 km, as 90% of them lie within the range (50-200) km. • The longitude distribution is highly non-uniform. One-half of the data have longitudes between 250º and 310º.

  7. Database –transition height hT • The O+ scale height obtained by the regression contains the 30% increase of plasma temperatures. • Simple theoretical considerations assure that the transition height should not change considerably when plasma temperature varies, although the density changes. The increased plasma temperature increases also the H+ scale height with the same proportion as that of O+ (with opposite sign). Therefore, near the transition height both ion densities increase, but the altitude where they become equal does not change.

  8. HT / hT ratio • It was found that the scale height and transition O+-H+ height, extracted from each individual measured Ne profile, highly correlate, with a correlation coefficient exceeding 0.8 at midlatitudes. The upper panel shows the model prediction, while the lower panel shows individual values in a HT/hT plot, taken from (30, 50) geomagnetic latitude in daytime winter. • The ratio HT/hT obtained from the individual profiles is modelled as a function of same input parameters as HT and hT.

  9. The new Topside Sounder Model (TSM) The scale height HT, transition height hT and their ratio Rt are modeled separately by the same type of polynomial. month: c0 + c1 sin(x) + c2 cos(x) + c3 sin(2x) + c4 cos(2x) local time: c0 + c1 sin(x) + c2 cos(x) + c3 sin(2x) + c4 cos(2x) glat: c0 + c1 x + c2 x2 + c3 x3 + c4 x4 + c5 x5+ c6 x6 sf: c0 + c1 x + c2 x2 Kp: c0 + c1 x + c2 x2 The new Topside Sounder Model (TSM) provides HT, hT and Rt for any set of above shown parameters in their defined ranges.

  10. Model results – daytime Individual daytime (10-16 LT) values of hT, HT, and their ratio Rt (red crosses) from winter (left) and summer (right) months. Solar flux (F107) ranges between 80 and 120, Kp>4. Model values (blue curves) refer to LT = 12 on January 1st (left) and July 1st (right), SF=100 and Kp=3.

  11. Model results - nighttime Individual nighttime (22-04 LT) values of hT, HT, and their ratio Rt (red crosses) from winter (left) and summer (right) months. Solar flux (F107) ranges between 80 and 120, Kp>4. Model values (blue curves) refer to LT = 00 on 1st January (left) and 1st July (right), SF=100 and Kp=3.

  12. Model results – local time dependence Individual values of hT, HT, and their ratio Rt (red crosses) from winter (left) and summer (right) months versus local time. Solar flux (F107) is limited to (80, 120), Kp<4. Model values (blue curves) refer to geomagnetic latitude 40N for January 1st (left) and July 1st (right), SF-100 and Kp=3.

  13. TSM performanceTSM provides hT, HT, and Rt as functions of month of the year, local time, geomagnetic latitude, solar flux (F10.7), and Kp index

  14. SCALE HEIGHT Latitude (HSA) PIM: highest values in summer, (unusually) high during the day NeQuick: (unusually) high values in the north hemisphere NeQuick: large differences between the hemispheres ( + discontinuity )

  15. TRANSITION HEIGHT Latitude (HSA) NeQuick: sharp discontinuityover the equator observed in the latitude profile of the transition height

  16. TSM Profiler (TSMP) = F2(h) TSMPдава формата на профила. Самият профил се получава като се спесифициратNmF2 иhmF2

  17. Съвременните йоносонди Digisonde на Lowell University (Bodo Reinisch et al)автоматично изчисляват електронния профил Ne под hmF2 и в добавъкдават една оценъчна scale height Hm (в предположение наα-Chapman разпределение около и над hmF2). Тази величина Hm впоследствие се използува за реконструкция на Ne внад-максимумната (topside) част на областта F. • Hm във формулата на α-Chapman представлява scale height на неутралната атмосфера. На височини достатъчно над hmF2, α-Chapman профила намалява експоненциално с градиент съответствуващ на 2 Hm. • Наличието на Hm, екстрактирана от реално измерени йонограми, дава възможност за комбиниране наизмерванията на Digisonde с моделните параметри на TSMP. Акомоделната HT се замести с Hm, то Digisonde посредствоммоделното отношение Rt може да получи подходящо преходно ниво hT и оттам да възстанови целия профил.

  18. 4D 4D 4D 4D 4D Hermanus Ground-based ionospheric sounders Nicosia Digisonde Network

  19. DIAS systemhttp://dias.space.noa.gr

  20. Scale height: TSM (HT) vs Digisonde (Hd) One year of data from Athens, Juliusruh, Chilton and Millstone Hill (Oct. 2000-Sep 2001) are used for the analysis. Digisonde derived Hm is multiplied by 2 to represent the plasma scale height, denoted as Hd (Hd=2*Hm). TSM provides ht, HT, and Rt for each Digisonde measurement. So, we have for any measurements a set of foF2, hmF2, Hd, hT, HT, and Rt. The histograms of all Hd and HTvalues show that Hd is systematically lower than Hs. TSM HT Digisonde Hd

  21. Scale height Histograms Digisonde Hd distribution is compared with the HT extracted from all available topside sounder Ne profiles. Red: Digisonde Scale Height Hd Green: TSM Scale Height Hs

  22. TSMP & Digisonde profiles Red curves show Digisonde –Chapman profiles. Dashed red curve shows O+ with Hm from ionogram. Solid red curve shows O+ profile with Hm multiplied by a factor of 2.4 (=2*1.2). H + density is obtained by TSMP for HТ=1.2Hm The total density Ne of TSMP (using HТ) and Digisonde &TSMP agree very well NmF2 = 6.6 E5 hmF2 = 406.7 km Hm = 41.4 km HT = 99.36 km hT = 880.6 km DIG O+ (Hm*2.4)

  23. Плазмосферни профили

  24. Нistogram of Hh values, accumulated from 14,628 measured profiles. • The most probable H+ scale height value is around 1200 km.

  25. The most probable value of the ratio surprisingly is not 16, but between 8 and 10

  26. scale height ratio vs latitude

  27. scale height ratio as a function of L Plasmasphere scale height is obtained as (9.cos2(glat)+4)Hs

  28. ▪ CHAMP reconstructed profiles ▪ Vary-Chap Function ▪ PIM ▪ NeQuick ▪ TSMP-assisted Digisonde profiling technique Electron density reconstruction techniques

  29. ▪ CHAMP reconstructed profiles ▪ Vary-Chap Function ▪ PIM ▪ NeQuick ▪ TSMP-assisted Digisonde profiling technique Electron density reconstruction techniques

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