Mesospheric noctilucent clouds

Mesospheric noctilucent clouds

The book presents the results of the study of dynamic and spectral features of such a little-studied phenomenon as mesospheric noctilucent clouds (NLCs). The results of the study of their dynamic and spectral characteristics are presented.

Vdovichenko V.D., Kirienko G.A. Mesospheric noctilucent clouds. Problems and solutions. LAP LAMBERT Academic Publishing 2013. ISBN: 978-3-659-46657-1. 285 p

Study of the dynamics and spectra of mesospheric noctilucent clouds

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The current problems of the study of mesospheric noctilucent clouds (NLCs) and possible their solutions, based on a large literary survey, are described in an accessible form in this book. Since the authors were repeatedly partaking in expeditions to North Kazakhstan for NLC observations, they present the results of their personal photographic and spectral observations, as well as methods and results of their processing. Because obtaining NLC «pure» spectra on a background of the twilight segment is difficult, the authors made a spectrometer for extended celestials and carefully researched it. In order to answer the controversial question of the possible luminescence of mesospheric noctilucent clouds, the authors conducted a spacious literature search, hoping to find likely candidates for the role of luminophores to explain an unusual bluish-silvery glow of this atmospheric phenomenon. It seems they are a success to find such an answer.

The book is offered to not only a wide range of readers, enthusiasts-observers of mesospheric noctilucent clouds and students, but it also can be useful for the scientists engaged in atmospheric optics.

Table of Contents

As a prologue. 5
Part 1. 7
There are four major questions on the nature of noctilucent clouds, but if all of them have answers?. 7
Introduction to NLCs problem.. 8
Historical review. 12
The mission of the AIM satellite. 14
Directions of NLC research: 16
Increase in NLC appearance frequency and in their field sizes 18
Prevalence of NLs 19
Chapter 1. 21
Why is there the lowest atmospheric temperature in the mesopause?. 21
Thermodynamics of the main layers of the atmosphere. 23
Effect of latitudinal and meridional circulation. 23
Upward and downward currents 26
Anthropogenic factor 29
The role of atmospheric acoustic-gravity waves 29
NLCs as a mirror of wave processes in the mesosphere. 31
Seasonal variations 33
Chapter 2. 35
What are the sources of condensation nuclei in the mesosphere?. 35
Likely sizes of the particles and their concentration. 35
Different approaches to explaining the phenomenon of NLCs 37
Cosmic dust 39
The Tunguska phenomenon. 41
The theory of explosions and volcanic eruptions 44
The role of electric fields, arising owing to the explosions and earthquakes 46
Ionospheric perturbations 49
Chapter 3. 51
What way does water vapor get into the mesopause?. 51
Rocket-borne researches 51
Hydroxyls in favor of H2O. 52
Possible sources of H2O in the mesosphere. 53
Turbulence or accretion?. 55
Comet theory. 56
Combustion of the hydrogen and reactions with CH4 57
The role of thunder clouds 58
Statistics of the thunderclouds 58
Sources of the air ionization. 60
Connection the lightnings with the cosmic rays 61
«Red Sprites» and «Blue Jets». 62
Observations of thunderstorm activity. 65
Chapter 4. 67
Why were NLCs not observed until 1885?. 67
Human factor or the explosion of Krakatau Volcano?. 67
Human factor and other causes 68
Variations in Earth’s magnetic field. 69
The explosion of Krakatau as a trigger 72
The largest volcanic eruptions 73
Conclusion. 80
Part 2. 81
Structure, dynamics and physical parameters of mesospheric noctilucent clouds obtained from their observations in Kazakhstan 81
Introduction. 81
The relevance and prospects of NLC research in Kazakhstan. 84
Goals and objectives of the Project 87
Photographic and video NLC observations. 88
Observations in 1996. 89
Expedition of 1998. 90
Observations of noctilucent clouds in Kazakhstan in 1998. 90
Expeditionary NLC observations in North Kazakhstan in 2006-2007. 95
The choice of reference points for the basis NLC observations 95
Optical-information expeditionary complex for NLC observations 96
Calculations of NLC visibility and testing optics 96
Making a database. 97
Methods of processing the observational data. 104
The main processing programs of NLC fields 104
Determination of the brightest NLC field heights and their distances from the observation base point 105
Preparation for image processing. 105
Projection of NLC fields on Earth’s surface. 110
Unique observations at Almaty. 113
The «NLC_Scan_Image» program.. 117
Analysis of NLC field brightness using color gradation. 119
Main results 120
Morphological characteristics of NLCs 120
A detailed description of NLCs observed and their dynamics 124
Observations of 2006. 124
Observations in 2007. 129
Sum up. 133
Part 3. 137
Spectral observations of the twilight segment and mesospheric noctilucent clouds in Kazakhstan in 2006-2007 137
A brief overview of NLC spectral observations 137
Observations of Grishin and Fogle. 138
Attempts of interpretation. 140
Satellite measurements of NLCs 142
Twilight segment study. 147
A bit of the history. 147
Spectrophotometry of twilight sky. 148
The role of single scattering. Twilight ray. 150
Equivalent path of the solar rays 152
Technique and results of the twilight sky spectrography. 156
The twilight sky glow. 156
Particular cases of the interpretation of the twilight sky sounding. 157
Precision photometry principles 162
Ozone absorption. 164
Our observations of the twilight segment. 167
Basic problems. 167
Complexity of observations and obtaining NLC pure spectra. 167
Requirements to the spectrometer and CCD matrix. 168
Description of equipment and its study. 169
Optical layout, design and appearance of the spectrometer 169
Testing the spectrometer 171
Main characteristics of the spectrometer. 171
Setting the sharpness of the image on the entrance slit 171
Calibration of wavelengths 172
The function of the spectrometer field across dispersion. 174
Combining NLC images and their spectra. 175
Standardization of the spectra. 177
Accounting for the Fraunhofer lines and telluric absorption bands 177
A transmission function of the spectrometer. The solar spectrum beyond the atmosphere. 179
Twilight segment spectra. 182
Conditions for observation in the evening and at night 182
Dependence of the intensity on the wavelength at different Z. 183
Dependence of the intensity on Z for different wavelengths 185
Problems of taking into account the air mass effect 185
Approximation formulas 187
Features of the ozone absorption. 190
New questions, new tasks 193
Spectra of NLCs 199
Spectral intensities of NLCs in relation to the Sun. 199
Processing algorithm of NLC spectra. The main problems and their solutions 199
Solution of the first problem.. 199
Solution of the second problem.. 201
Solution of the third problem.. 203
Solution of the fourth problem.. 203
Dependence of the NLC luminosity on the Sun depression angle. 203
Solution of the fifth problem.. 205
The program of processing NLC spectra. 208
Main results of the NLC spectra processing. 210
Analysis of spectral intensity of NLCs 219
Comparison of our NLC spectra with the NLC spectra of Grishin and Fogle. 223
Some aspects of the Rayleigh and aerosol scattering. 226
Luminescence. 233
Basic definitions 233
The types of excitation. 233
Necessary conditions for the luminescence. 236
Some rules for the luminescence spectra. 237
Variety of substances capable of luminescence. 240
Luminescence of comets 242
Comparison of NLC spectra with the spectra of some fluorescent compounds 245
Fluorescence of oil and oil products 246
Proteins, amino- and nucleic acids, phenols 250
Fluorescence of natural dissolved organic matter 250
Spectral response of the natural water 253
Is the luminescence possible in the mesopause?. 257
The mechanism of transfer of fluorescent matter to the mesosphere. 261
Conclusion. 262
Aero plankton. 265
Bibliography 269-280