MgE71241:1attf:3(t At-- 0 -3 5t5M I:. N1144±TitoD riziMinliJ VAT .9f 1 ...

More documents

Recommendations

Info

2 1. INTRODUCTION 300-500 km Dnvecti o n- driv e) aurora ion drag 1 I aurora ora 80-90 km precipitation i f t wind ? I I 1I / (Joule 17 I it heating) I II 1 7.ndr) wic thermal expansion —* large-scale atmospheric gravity wave (ex.TID) EUV/UV heating breaking wind ? gravity wave pressure gradient '" ,---'•-r--... OM0Elves vY Sprites equatorial anomaly Earth high low latitude latitude Figure 1.1. Scheme of thermospheric phenomena and physical processes models. It is well known that thermospheric densities and temperatures vary with solar activity and that such variations follow those of solar decimetric (F10.7) flux. This radio flux, which has been catalogued continuously over many years, does not act directly on the upper atmosphere itself, but correlates with the experimental data sets of thermospheric temperatures [Hernandez, 1983]. The second important energy sources for the thermosphere is solar wind energy injected primarily through auroral processes. Auroral energy often exceeds the energy due to solar EUV/UV radiation during geomagnetic storms or substorms. Further, auroral activity changes so quickly that thermospheric temperature and wind at high-latitude change mo- mentarily. Consequently a study of thermospheric response to auroral activity is essential for the investigation of dynamical processes of the thermosphere. The auroral energy heats the thermosphere through Joule heating and the collisional slowing-down process of energetic particles precipitating from the magnetosphere. The rate of Joule and particle heating can be estimated from ionospheric parameters. Foster et al. [1983] calculated the Joule heating
1. INTRODUCTION rate at high latitude using the electric field intensity and the Pederson conductivity which were derived from simultaneous measurements of ion drift velocity and precipitating charged particle flux by the AE--C satellite. Their result indicated that high-latitude Joule heating occurs in a roughly-oval pattern consisting of three distinct heating regions: the dayside cleft, the region of sunward ion convection at dawn and dusk, and the midnight sector. The total global thermospheric heating due to particle precipitation was estimated to be lower than Joule heating from recent satellite measurements of precipitating particle fluxes [Evans, 1986; Fuller-Rowell and Evans, 1986]. Another important energy source for the thermosphere is wave energy coming from the middle and lower atmosphere. The energy transport processes due to such waves have been studied by Garcia and Solomon [1985], Fritts et al. [1996] and many other researchers. The effect of such waves on the global thermospheric heat budget, however, has not been parameterized yet. 1.2 Modeling and simulation of the thermosphere 1.2.1 Thermospheric general circulation models In recent years various kinds of numerical models have been developed to study the global thermospheric circulation, energetics, composition structure and their response to solar and auroral activities. The developed thermospheric general circulation models (TGCMs) have been used to simulate the various patterns of the thermospheric winds and temperatures, e.g., the solar-driven thermospheric circulations in equinox and solstice conditions, the response of the thermosphere to auroral particle precipitation and substorrn energy input, and the mean high-latitude thermospheric circulation. Furthermore, in order to investigate the dynamical features of the thermosphere, comparative studies of model calculations and a large number of satellite observations have been made. Killeen et al. [1986] obtained the mean global-scale circulation in the northern hemi- sphere F region by collecting and averaging all available data from the DE-2 satellite and the network of ground-based Fabry-Perot interferometers. The mean circulation patterns were compared with the predictions of the National Center of <strong>At</strong>mospheric Research (NCAR) TGCM. From this study they concluded that (1) instrumentation deployed around the globe and on satellites can provide powerful, composite data sets that can be used to monitor the mean dynamical state of the earth's thermosphere and that (2) the mean thermospheric (F 3
Page 1 and 2: A Study on Middle-scale Variations
Page 3 and 4: Abstract The solar wind energy inje
Page 5 and 6: Contents Acknowledgments Abstract i
Page 7 and 8: 6 Discussions CONTENTS 6.1 Nighttim
Page 9 and 10: x LIST OF FIGURES 2.10 2.11 2.12 2.
Page 11 and 12: xii LIST OF FIGURES 4.8 Fringe prof
Page 13 and 14: xiv LIST OF FIGURES 5.23 Same as Fi
Page 15: Chapter 1 Introduction 1.1 The Eart
Page 19 and 20: 1. INTRODUCTION 5 Analogous to the
Page 21 and 22: 1. INTRODUCTION 7 thermospheric cir
Page 23 and 24: 1. INTRODUCTION 9 Okano and Kim [19
Page 25 and 26: 1. INTRODUCTION confirmed that the
Page 27 and 28: 1. INTRODUCTION 13 and EUV solar ra
Page 29: 1. INTRODUCTION 15 analytical descr
Page 32 and 33: 18 2. DEVELOPMENT OF THE FABRY-PERO
Page 52 and 53: 38 Er e Z O CE F-F-a Ur) h^-• O 0
Page 54 and 55: i 40 2. DEVELOPMENT OF THE FABRY-PE
Page 56 and 57: 42 2. DEVELOPMENT OF TI E FABRY-PER
Page 58 and 59: 44 2. DEVELOPMENT OF THE FABRY -PER
Page 60 and 61: 46 3. OBSERVATIONS 1) The adjustmen
Page 63: (b) 3. OBSERVATIONS (a) !7lasigum 1
Page 67 and 68:
3. OBSERVATIONS Table 3.1. Summary
Page 69:
____------- wind velocity line-of-s
Page 73 and 74:
3. OBSERVATIONS 59 All operations o
Page 75 and 76:
Chapter 4 Procedures of Data Anal y
Page 77 and 78:
4. PROCEDURES OF DATA ANALYSIS 63 2
Page 79 and 80:
-, (a) 1000 500 (b) 1000 500 0 0 4.
Page 81 and 82:
as 4. PROCEDURES OF DATA ANALYSIS 6
Page 83 and 84:
wind velocity v is given by 4. PROC
Page 85 and 86:
80 c..1 0 40 ,7u cn 20 0 0 4. PROCE
Page 87 and 88:
,-C btu cu ...-1 7.) al +t) CI a) 1
Page 89 and 90:
o 5000 4. PROCEDURES OF DATA ANALYS
Page 91:
(a) 800 600 (i) =g-, 400 ›.- Pc C
Page 94 and 95:
80 5. THER.MOSPIIERIC NEUTRAL WINDS
Page 96 and 97:
8 2 5_ THERMOSPHERIC NEUTRAL WINDS
Page 98 and 99:
I E 84 5. TILERMOSPHERIC NEUTRAL WI
Page 100 and 101:
I 05 8 6 5. THERMOSPILERIC NEUTRAL
Page 102 and 103:
88 5. THERMOSPHERIC NEUTRAL WINDS O
Page 105:
Line-of-Sight Neutral Wind Velociti
Page 109 and 110:
5. THERMOSPIIERIC NEUTRAL WINDS OVE
Page 111 and 112:
0 Cf) CO • imme F.4 Ca) O 7-1)` c
Page 113 and 114:
$.4 RS 4—) 0.0 X.4 P"'"a Pm( tri
Page 115 and 116:
4 0 • U) 4.) O •-4 • -I•ma
Page 117 and 118:
P-1 • p^^4 4.4 • •.* prZ •p
Page 119:
5. THERMOSPHERIC NEUTRAL WINDS OVER
Page 123:
Page 127:
Page 131 and 132:
Chapter 6 Discussions 6.1 Nighttime
Page 133 and 134:
a_ -1 7 6 5 4 3 2 -2 1 0 - 3 _4 -5
Page 135 and 136:
I = - E ,---, c.) u.) a) ..... c.;
Page 137 and 138:
1 (13 C 7)4 "CI ,;3 C N 0 z 0, 2 Ho
Page 139 and 140:
6. DISCUSSIONS 125 is seen in numer
Page 141 and 142:
6. DISCUSSIONS 6.3 Middle-scale atm
Page 143:
6. DISCUSSIONS 129 15:50:00 lb:00:0
Page 146 and 147:
132 6. DISCUSSIONS It is very inter
Page 148 and 149:
CAD MAGNE TOGFIRM AT STOWR STA T I
Page 150 and 151:
136 7. CONCLUSIONS 5) Nighttime var
Page 152 and 153:
138 REFERENCES Conde, M., and R. W.
Page 154 and 155:
140 REFERENCES Hernandez, G., R. W.
Page 156 and 157:
142 REFERENCES Rees, D., and A. H.
Page 158 and 159:
Appendix A Sequential wind data in
Page 160 and 161:
Line-of-sight neutral wind velociti
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
Page 174 and 175:
show all

MgE71241:1attf:3(t At-- 0 -3 5t5M I:. N1144±TitoD riziMinliJ VAT .9f 1 ...

Create successful ePaper yourself

Delete template?

Save as template?