Долготная статистика плазменных пузырей, видимых на высотах верхней ионосферы в концентрации Не + Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation (IZMIRAN) Troitsk Moscow region RUSSIA LARISA SIDOROVA

1.Области пониженной концентрации Не + (или субпровалы) 2.Почему они были отнесены к плазменным пузырям (баблам) экваториальной ионосферы? 3.Долготная статистика 4.Влияние солнечной активности 5.Заключение Содержание

Questions WHAT are the He + density depletions? WHERE is the typical region of their occurrence?

ISS-b Data Equatorial trough in He+ density Equatorial trough in He+ density 7:51 7:57 8:04 8:10 8:16 8:23 8:29 8:36 8:42 UT 20:01 22:54 0:10 0:52 1:23 1:53 2:31 3:32 5:53 LST INVLAT DIPLA 4:32 4:38 4:44 4:51 4:57 5:04 5:10 5:16 UT 22:25 23:42 0:25 0:57 1:28 2:09 3:20 5:59 LST INVLAT DIPLA LIT H e + D E N S I T Y, c m - 3 LIT ISS-b 16 Feb.1979 Rev.: 4903 ISS-b 21 Apr.1979 Rev.: 5761 H e + D E N S I T Y, c m - 3 Typical He + densities as measured by ISS-b ( ) F 10.7 ~200, the topside ionosphere (~1100 km) The depletions or so- called subtroughs in He + density. Karpachev, Sidorova, ASR, 2002

Equatorial trough Equatorial trough He + density subtroughs Karpachev, Sidorova, 2002 Subtroughs should be defined as a well- pronounced depletion in He + density from several times to two orders of magnitude density may drop within 5-10 latitude equatorward of LIT.

He + density subtroughs Karpachev, Sidorova, 2002 ~ 440 cases in ~4000 passes ~ 260 cases in ~4000 passes RESEARCH SUBJECT

GUVI 1356 Å PLASMA BUBBLES Paxton et al., 2005 This idea was put forward after comparative analyses with typical characteristics of equatorial plasma bubbles with dynamics of the equatorial trough in He + density with equatorial vertical plasma drift velocity with ESF QUESTION: Why He + density depletions were interpreted as plasma bubbles?

GUVI 1356 Å EQUATORIAL PLASMA BUBBLES Paxton et al., 2005 with typical characteristics of the plasma bubbles POST-SUNSET HOURS Typical local time of the He + density depletion occurrence is the post-sunset hours like for ESF and equatorial plasma bubbles. TRAINS OF THE DEPLETIONS There are the single cases of the depletions and there are the trains of the depletions, observed in the consequent satellite passes. They occur like the trains of the plasma bubbles, revealed in the different observations (optical, radar, ionosonde and satellite) for example GUVI. Day Night NOV NOV NOV INVARIANT LATITUDE, degr. 4 3 lg(He+) 2 NOV NOV.1979 Night GUVI 1356 Å COMPARISON

with latitudinal dynamics of the equatorial trough in He + density Subtrough minimums Equatorial trough crests in He + density LATITUDINAL DYNAMICS The latitudinal dynamics as function of LT for the subtrough minimums and for the equatorial trough crests. Both dynamics have the same parallel character. It suggests, that there is connection between the depletions and the equatorial vertical plasma drift, having a great importance for equatorial trough generation. Sidorova, ASR, 2007 COMPARISON Southern Hemisphere September-October 1979 I N V A R I A N T L A T I T U D E, d e g. LT, hours

SUBTROUGH DEPTH Averaged plasma drift velocity on AE-E satellite and Jicamarca UHF radar data LT, hour 26 LT, hour SUMMER S U B T R O U G H V A L U E, n EQUINOX V E R T I C A L D R I F T V E L O C I T Y, m / s Subtrough Depth / Vertical Plasma Drift: CORRELATION Variations of the subtrough depth and the equatorial vertical plasma drift velocity as function of LT were compared. As reference the averaged velocity data, taken from Dr. Fejer articles, were used. It was revealed that there is striking similarity in the development dynamics for the different seasons (for example, equinox and summer). R~0.72 Fejer, ATP, 1981 Fejer et al., JGR, The best correlation (~0.72) was found for equinox months. It was concluded that there is the strong connection between this phenomena. with equatorial vertical plasma drift velocity COMPARISON

SUBTROUGHS DIP LATITUDE, degr. Equator Topside ionosphere HEIGHT, km and subtrough profiles BUBBLE RISE SCHEME Не + Density

Sidorova, ASR, 2007 H apex ~2000 km and more hF ~ 400 km L=H apex - hF L ~ 1600 km T= hours V=L/T= m/s RISE VELOCITY ESTIMATION Moreover, the estimation of the model rise velocity for He + density depletions shows that the velocity is ~150 m/s and slightly more. This estimation is in well agreement with the typical plasma bubble velocities, obtained for the same period from the ionosonde [1], VHF radar [2], AE-C [3] satellite observations LT, hour 2 LT, hour SUMMER S U B T R O U G H V A L U E, n EQUINOX V E R T I C A L D R I F T V E L O C I T Y, m / s [1] Abdu et al., JGR. (1983) [2] Woodman, La Hoz, JGR. (1976) [3] McClure et al., JGR. (1977) ISS-b altitudes DIP LATITUDE, deg. Altitude, km Plasmasphere Equator Topside ionosphere

LOCAL TIME, hours LOCAL TIME, hours R=0.67 R=0.6 Cachoeira Paulista, 23 Abdu et al.,ASR, 2000 Fortaleza, 4 Sidorova, ASR, 2007 ISS-b Depletion/ESF Statistics: CORRELATIONS The comparative analysis shows good enough correlations. It is revealed that the correlation coefficient is about ~0.67 for the subtroughs and station Fortaleza, and about ~0.6 for the subtroughs and station Cachoeira Paulista. with ESF statistics COMPARISON

LOCAL TIME, hours LOCAL TIME, hours LOCAL TIME, hours Sidorova, ASR, 2007 Abdu et al., ASR, 2000 COMPARISON with ESF statistics Fortaleza, 4 Cachoeira Paulista, 23 ISS-b

He + Density Depletions (Bubbles) DIP LATITUDE, deg. Altitude, km Ionosphere Plasmasphere Equator ISS-b altitudes All mentioned facts allow to put forward the idea that the ESF/plasma bubbles and He + density depletions may be considered as phenomena of the same plasma bubble origin. In other words the plasma bubbles, reaching the topside ionosphere altitudes, are mostly seen not in electron density but in He + density. (At this picture you can see the model of the plasma bubble development at the topside and plasmasphere altitudes.) Sketch of Plasma Bubble Dynamics Topside ionosphere

PUBLICATIONS Article: Distinction and classification of the troughs and subtroughs in He+ density from ISS-b satellite data at km altitudes, A. Karpachev, L. Sidorova, J. Atm. Solar-Terr. Phys., 65, , Article: He+ density topside modeling based on ISS-b satellite data, L. Sidorova, Advances in Space Research, 33, , Article: Plasma bubble phenomenon in the topside ionosphere L. Sidorova, Advances in Space Research, 39 (2007), , DOI: /j.asr Article: Equatorial Plasma Bubbles at Altitudes of the Topside Ionosphere, /j.asr L. Sidorova, Geomagnetism and Aeronomy, 49 (1), 56-65, Book: Topside plasma bubbles bubbles, seen as He+ density depletions L. Sidorova, International Conference, Fundamental Space Research, Conference Proceedings, Sunny Beach, Bulgaria, Sept., (2008), p

MOTIVATION There is very well COINCIDENCE of the ESF regional maps, obtained over Brazilia, and the global map of He + density depletion statistics WHY? LOCAL TIME, hours R=0.67 R=0.6 Cachoeira Paulista, 23 Abdu et al., ASR, 2000 Fortaleza, 4 Sidorova, ASR, 2007 ISS-b

Equatorial F-region Irregularities He+ Density Depletions For validation of the obtained results it is necessary to have the detailed He + density depletion occurrence probability with respect to longitude - to compare them with same statistics of the equatorial F-region irregularities. We believe that comparison will show the similarity of these statistics. We also believe that comparison will show the predominant area of the both statistics, covered the Brazilian longitudes ( ) or South Atlantic Anomaly (SAA). Lets test these assumptions. ASSUMPTIONS LONGITUDINAL OCCURRENCE PROBABILITY Similarity ? Predominant distribution over SAA ( ) ?

COMPARED DATA Study DataParameterLT interval HeightsLatitudesYearsF 10.7 Present studyISS-bP He+ den.dep LT~1100 km INVLAT Maryama, Matuura, 1980, 1984 ISS-bP RSF, ESF LT~1100 km 20 DIPLAT McClure et al., 1998AE-EP LT km 20 DIPLAT Basu et al., 1976OGO-6P LT km 20 DIPLAT ~150 Su et al., 2006ROCSATP LT~600 km 15 DIPLAT Watanabe, Oya, 1986HinotoriP B LT650 km 20 DIPLAT 1981~200 For this aim lets take the data, pointed in the table

Equatorial F-region Irregularities McClure et al., JGR, 1998, AE-E, P Maruyama, Matuura, RRL,1980, ISS-b, P RSF Watanabe, Oya, JGG, 1986, Hinotori, P B650 Basu et al., Radio. Sci., 1976, OGO-6, P 1 Su et al., JGR, 2006 ROCSAT, P 3

SEASONAL INTERVALES SEASON Present studyMaryama, Matuura, 1980, 1984 McClure et al., 1998 Su et al., 2006 Watanabe Oya, 1986 Basu et al., 1976 WINTER22 окт.-22 фев.10 нояб.-12 марта ноябрь-январьдекабрьноябрь- январь ноябрь- декабрь VERNAL22 янв.-22 мая9 фев.-13 июня февраль- апрель мартфевраль- апрель SUMMER22 апр.-22 авг.апрель-июнь, август май-июльиюньмай-июль AUTUMN22 июл.-22 нояб. 11 авг.-11 дек.август- октябрь сентябрьавгуст- октябрь

INTEGRATED EQUATORIAL DATA

He + DENSITY DEPLETIONS STATISTICS WINTER VERNAL SUMMER AUTUMN SOUTHERNH EMISPHERE NORTHERN HEMISPHERE

COMPARISON: VERNAL He + Density Depletions NORTH F-region Irregularities: Integrated Data EQUATOR He + Density Depletions SOUTH

COMPARISON: AUTUMN He + Density Depletions NORTH F-region Irregularities: Integrated Data EQUATOR He + Density Depletions SOUTH

COMPARISON shapes of variations AUTUMN VERNAL It was revealed that the EFIs show good enough similarity both with northern and southern variations of the depletions. The depletion statistic plots can be shifted slightly in longitudes, however they have the common (with irregularities) shape in variations. Hence, our primary assumption about similarity in shape of variations is validated.

COMPARISON: WINTER He + Density Depletions NORTH He + Density Depletions SOUTH F-region Irregularities: Integrated Data EQUATOR

COMPARISON: SUMMER He + Density Depletions NORTH F-region Irregularities: Integrated Data EQUATOR He + Density Depletions SOUTH

COMPARISON shapes of variations WINTER SUMMER It was revealed that the EFIs show good enough similarity both with northern and southern variations of the depletions. The depletion statistic plots can be shifted slightly in longitudes, however they have the common (with irregularities) shape in variations. Hence, our primary assumption about similarity in shape of variations is validated.

COMPARISON seasonal distributions All depletion statistics were gathered into the map, plotted with respect to season and longiude for Northern hemisphere Southern hemisphere

COMPARISON seasonal distributions 240° ° - 320° - 0 ° - 60 °

TABLE: He + (H + ) depletion observations SatelliteDepletion in ions Year, monthRegistration altitudes, km PublicationsF 10.7 Solar cycle OGO-4H+ He+ 21 Sept (7 cases) 9,10,18 Feb April ~800 Taylor,Grebowsky,Walsh, 1971 Taylor and Cordier, 1974 Chen,Grebowsky, Taylor, 1975 Taylor,Grebowsky, Chen, 1975 ~ ~150 ~ high- maximal, 20 th OGO-6H+ He+ 10 November 1969 August ( 15 cases), October ( 50 cases), Nov. (2 cases) Taylor and Cordier, 1974 Present study ~150 maximal, 20 th Oreol-1He+10 January Ershova et al., 1977~140high, 20 th ISIS-2H+4-6 August Brace et al., 1974~120moderate, 20 th Oreol-2H+8-9 January January Sivtseva and Ershova, 1977 Sivtseva et al., 1982 ~80low, 20 th ISS-bHe+Aug – Dec (700 cases for ~4000 passes) Karpachev and Sidorova, 1999~ high, 21th DE-2H+ He Nov ~1000 Horwitz, Comfort et al., 1990~200maximal, 21th Intercosmos- Bulgaria-1300 H+12 August 1981– 30 December Gousheva et al, 2006~200maximal, 21 th

Oreol-1 Ershova et al. Kos. Issl., 1977 DE-1; DE-2 Horwitz et al. JGR, 1990 OGO-6 Present study OGO-4 Taylor, Grebowsky et al.,JATP,1975 ISS-b Karpachev, Sidorova JASTP, 1999 He + DEPLETIONS and SOLAR ACTIVITY 1981 F 10.7 ~200 max., 21 th 1972 F 10.7 ~ 140 high, 20 th 1968 F 10.7 ~150 max., 20 th 1969 F 10.7 ~160 max., 20 th F 10.7 ~200 high, 21 th Publications Years F 10.7 Solar cycle Many cases of observations were revealed on the OGO-4, the OGO-6, DE-2 and ISS-b data. It was also noticed that the most of the cases are revealed during the high and maximal solar activity periods.

It is reasonable to ask. It is reasonable to ask. Why the topside ionosphere plasma Why the topside ionosphere plasma bubbles, seen as He + density bubbles, seen as He + density depletions, are more visible during depletions, are more visible during high and maximal solar activity periods? high and maximal solar activity periods? QUESTION

Arecibo Ion Data: October 2001Arecibo Ion Data: October 1997 He+He+ He+/Ne Lets pay attention on the He + density background during solar maximums and minimums, taken from Wilford article. You can see very well developed He + density layer at the topside ionosphere altitudes in solar maximum and and poor layer in solar minimum. Wilford et al., JGR, 2003 SOLAR MAXIMUM SOLAR MINIMUM ABSOLUTE CONTENT ABSOLUTE CONTENT FRACTIONAL CONTENT FRACTIONAL CONTENT ABSOLUTE CONTENT ABSOLUTE CONTENT FRACTIONAL CONTENT FRACTIONAL CONTENT He + DENSITY BACKGROUND

And now lets take the model of the plasma bubble formation as suggested by Woodman and La Hoz. You can easily notice that the value of the background density is very important for the bubble formation. Apparently, this picture is also correct if the separate plasma component is under consideration. I mean the He + density. Woodman and La Hoz, JGR, 1976 BUBBLE FORMATION: classic schema

The model plasma bubble and the real ESF/plasma bubbles, taken from radar observation. PLASMA BUBBLES AND ESF Woodman and La Hoz, JGR, 1976 Tsunoda et al., JGR, 1982 Radar (ALTAIR) Observations Schematic Representation

And now lets integrate the model plasma bubble development and the background in He + density. MODEL: plasma bubbles, seen as He + density depletions SOLAR MAXIMUM SOLAR MINIMUM

Really, the more convenient conditions for observations of the He + density depletions take place during high and maximal solar activity. Because there is very well developed He + density layer in the topside ionosphere during this period. Arecibo Ion Data: October 2001 Arecibo Ion Data: October 1997 On the other hand there are the bad conditions for the He + density depletion observation in solar minimum, when the background layer is poor. Good conditions for observations Bad conditions for observations SOLAR MAXIMUM SOLAR MINIMUM MODEL: plasma bubbles, seen as He+ density depletions

Обнаружено довольно хорошее подобие долготных статистик экваториальных неоднородностей F-области и областей пониженной концентрации He + (субпровалов). Выявлено, что регион долготного доминирования (преобладания) субпровалов He + - это регион Америки, Атлантики и Африки. Выявлено, что области пониженной концентрации He + (субпровалы) – это типичное явление верхней ионосферы для периодов высокой и максимальной солнечной активности. Полученные результаты могут рассматриваться в качестве нового свидетельства идеи экваториального происхождения субпровалов в концентрации He +. SUMMARY

СПАСИБО ! Acknowledgements I express my gratitude to ISS Research and Operation Committee, Japan, for providing the opportunity to us the ISS-b data. The author would like to express sincere thanks to Dr. Yu.Ya. Ruzhin (Russia) Dr. A.T. Karpachev (Russia) Dr. M.A. Abdu (Brazil) Dr. R.F. Woodman (Peru) Dr. R. Tsunoda (USA) for the useful advices and discussions.

ОБЛАСТИ КОНКУРЕНЦИИ /ДОМИНИРОВАНИЯ Не+ Heelis et al., J. Geophys. Res., 1990 H 900 km O+ He+

ОБЛАСТИ КОНКУРЕНЦИИ /ДОМИНИРОВАНИЯ Не+ Heelis et al., J. Geophys. Res., F 10.7 ~200 H 900 km O+ He+

Возможные высоты подъема плазменного пузыря О возможности существования плазменных пузырей на высотах верхней ионосферы говорилось неоднократно (см., например, (Woodman, La Hoz, 1976; Tsunoda et al., 1982). Более того существуют сообщения о том, что плазменные пузыри «видят» на высотах 2500 км (Sahai, 1994) и даже выше – 3500 км (Burke, 1979). Ряд авторов полагает, что статистически «потолок» высоты обнаружения плазменных пузырей (потолочная- ceiling height) находится приблизительно на 2000 км (Su, 2006). Наконец, эти утверждения подкрепляются результатами численного моделирования (см., например, Huba et al. 2008), согласно которым плазменные пузыри могут подниматься до высот 1600 км и выше. Sahai, Y. et al., J. Atmos. Terr. Phys., 1994, V. 56, P Burke, W.J. et al., Planet. Space. Sci., 27, 593, Su, S.-Y. et al., J. Geophys. Res., 111, A06305, doi: /2005JA011330, Huba, G.R. et al., Geophys. Res. Lett., V. 35, L10102, doi: /2008GL033509, 2008.

Declination angle =20є Equator Height =350 km Maruyama, JGR, 1996 Positive values are for southward orientation. southward orientation. Magnetic meridional wind component For comparison the diurnal variations of the magnetic meridional wind component was chosen. These calculations were made by Dr. Maruyama on the base of the empirical model of Hedin for the different seasons, for equator, declination angle about 20є and F- region altitude.. Model calculations, based on HWM90 model (Maruyama, JGR, 1996) Diurnal variations of the magnetic meridional wind component: different seasons.

So, according to these results the generation of He + density depletions seriously suffer from meridional wind. It is clearly seen the modulation effect of the occurrence probability from meridional wind. The local time occurrence probability can be significantly suppressed by the wind of as northward orientation (negative values) as southward orientation (positive values). COMPARISON WINTER R=0.7SUMMER R=0.67EQUINOX R=0.87 PROBABILITY,%