Pub Date : 1996-07-01DOI: 10.1016/0021-9169(95)00079-8
K. Krishna Moorthy, Prabha R. Nair, B.V. Krishna Murthy, S.K. Satheesh
The time evolution of the perturbations in aerosol spectral optical depths associated with the Mt. Pinatubo volcanic eruption of June 1991 is investigated using a ground-based multiwavelength solar radiometer at the tropical station, Trivandrum. The spectral optical depths of the volcanic aerosols deduced from the radiometer data are inverted to retrieve the size distributions of the particles, from which the effective radius and columnar mass loading are estimated. Observations showed that during the initial phase (within one year after the eruption) the optical depths showed fluctuations with two peaks, one in November 1991 and another in February 1992 superposed over a very weak decreasing trend. During this period, the size distributions have been generally bimodal, with a secondary large particle mode occurring at ∼0.75 μm, and the columnar mass loading varied between about 170 and 110 mg m−2. The optical depths and mass loading decreased with an e-folding time of about 15 months. The effective radius is found to increase from ∼0.35 μm in September 1991 to ∼0.60 μm in October 1992 and then remain rather steady, while the mass loading decreased to reach near-background levels (within error limits) by early 1993.
{"title":"Time evolution of the optical effects and aerosol characteristics of Mt. Pinatubo origin from ground-based observations","authors":"K. Krishna Moorthy, Prabha R. Nair, B.V. Krishna Murthy, S.K. Satheesh","doi":"10.1016/0021-9169(95)00079-8","DOIUrl":"10.1016/0021-9169(95)00079-8","url":null,"abstract":"<div><p>The time evolution of the perturbations in aerosol spectral optical depths associated with the Mt. Pinatubo volcanic eruption of June 1991 is investigated using a ground-based multiwavelength solar radiometer at the tropical station, Trivandrum. The spectral optical depths of the volcanic aerosols deduced from the radiometer data are inverted to retrieve the size distributions of the particles, from which the effective radius and columnar mass loading are estimated. Observations showed that during the initial phase (within one year after the eruption) the optical depths showed fluctuations with two peaks, one in November 1991 and another in February 1992 superposed over a very weak decreasing trend. During this period, the size distributions have been generally bimodal, with a secondary large particle mode occurring at ∼0.75 μm, and the columnar mass loading varied between about 170 and 110 mg m<sup>−2</sup>. The optical depths and mass loading decreased with an e-folding time of about 15 months. The effective radius is found to increase from ∼0.35 μm in September 1991 to ∼0.60 μm in October 1992 and then remain rather steady, while the mass loading decreased to reach near-background levels (within error limits) by early 1993.</p></div>","PeriodicalId":100754,"journal":{"name":"Journal of Atmospheric and Terrestrial Physics","volume":"58 10","pages":"Pages 1101-1116"},"PeriodicalIF":0.0,"publicationDate":"1996-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9169(95)00079-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53071221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-01DOI: 10.1016/S0021-9169(96)90060-4
J. London
{"title":"Global change and relevant space observations","authors":"J. London","doi":"10.1016/S0021-9169(96)90060-4","DOIUrl":"10.1016/S0021-9169(96)90060-4","url":null,"abstract":"","PeriodicalId":100754,"journal":{"name":"Journal of Atmospheric and Terrestrial Physics","volume":"58 10","pages":"Pages 1189-1190"},"PeriodicalIF":0.0,"publicationDate":"1996-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9169(96)90060-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"112486166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-01DOI: 10.1016/S0021-9169(96)90061-6
W.J. Burroughs
{"title":"Solar-terrestrial variability and global change","authors":"W.J. Burroughs","doi":"10.1016/S0021-9169(96)90061-6","DOIUrl":"10.1016/S0021-9169(96)90061-6","url":null,"abstract":"","PeriodicalId":100754,"journal":{"name":"Journal of Atmospheric and Terrestrial Physics","volume":"58 10","pages":"Pages 1190-1191"},"PeriodicalIF":0.0,"publicationDate":"1996-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9169(96)90061-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55445305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-01DOI: 10.1016/S0021-9169(96)90066-5
A. Hewish
{"title":"Physics of the inner heliosphere, vol. II—particles, waves and turbulence","authors":"A. Hewish","doi":"10.1016/S0021-9169(96)90066-5","DOIUrl":"10.1016/S0021-9169(96)90066-5","url":null,"abstract":"","PeriodicalId":100754,"journal":{"name":"Journal of Atmospheric and Terrestrial Physics","volume":"58 10","pages":"Pages 1193-1194"},"PeriodicalIF":0.0,"publicationDate":"1996-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9169(96)90066-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55445433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-01DOI: 10.1016/S0021-9169(96)90062-8
I.N. James
{"title":"Fluid mechanics of the atmosphere","authors":"I.N. James","doi":"10.1016/S0021-9169(96)90062-8","DOIUrl":"10.1016/S0021-9169(96)90062-8","url":null,"abstract":"","PeriodicalId":100754,"journal":{"name":"Journal of Atmospheric and Terrestrial Physics","volume":"58 10","pages":"Page 1191"},"PeriodicalIF":0.0,"publicationDate":"1996-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9169(96)90062-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55445315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-01DOI: 10.1016/0021-9169(95)00102-6
D.Y. Zhang, K.D. Cole
The problem is formulated, and boundary conditions are developed, in order to solve numerically the equations for the penetration of hydromagnetic waves of horizontal cylindrical symmetry through a stratified high latitude ionosphere and atmosphere due to sources above the ionosphere. There are two orthogonal polarization modes. The numerical results are shown for various cases. It is found that near the ground the horizontal components of both the electric and magnetic fields along the circumference direction are much smaller than the radial components.
{"title":"Penetration of hydromagnetic waves of cylindrical symmetry through the high latitude ionosphere","authors":"D.Y. Zhang, K.D. Cole","doi":"10.1016/0021-9169(95)00102-6","DOIUrl":"10.1016/0021-9169(95)00102-6","url":null,"abstract":"<div><p>The problem is formulated, and boundary conditions are developed, in order to solve numerically the equations for the penetration of hydromagnetic waves of horizontal cylindrical symmetry through a stratified high latitude ionosphere and atmosphere due to sources above the ionosphere. There are two orthogonal polarization modes. The numerical results are shown for various cases. It is found that near the ground the horizontal components of both the electric and magnetic fields along the circumference direction are much smaller than the radial components.</p></div>","PeriodicalId":100754,"journal":{"name":"Journal of Atmospheric and Terrestrial Physics","volume":"58 10","pages":"Pages 1165-1170"},"PeriodicalIF":0.0,"publicationDate":"1996-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9169(95)00102-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53071856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1996-07-01DOI: 10.1016/S0021-9169(96)90059-8
S.E. Hobbs
{"title":"Climate Change 1992: The supplementary report to the IPCC scientific assessment","authors":"S.E. Hobbs","doi":"10.1016/S0021-9169(96)90059-8","DOIUrl":"10.1016/S0021-9169(96)90059-8","url":null,"abstract":"","PeriodicalId":100754,"journal":{"name":"Journal of Atmospheric and Terrestrial Physics","volume":"58 10","pages":"Page 1189"},"PeriodicalIF":0.0,"publicationDate":"1996-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0021-9169(96)90059-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"55445287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Thomson scattering technique has been employed for the observation of turbulent waves excited by a relativistic electron beam. The frequency and k-spectra of the Langmuir waves are measured both in the excited and damped regions. The waves interact directly with the beam electrons inside a narrow section of k-sppace amid the region occupied by the non-resonant waves, which concentrate near k ∼ ωpe/c. Both resonant and non-resonant waves hold equal (to within an order of magnitude) amounts of energy. Incoherent scattering of the second harmonic of a Nd : glass laser is used to measure the time history of the electron distribution function including the super thermal tails. The typical beam and plasma parameters are as follows: (ne ∼ 1015 cm−3, nb/ne ∼ 10−4, B = 1–4 T, tb = 100–200 ns). The peculiarity of these experiments is the presence of a strong magnetic field (ωBec/ωpeVTe ⪢ 1, butcope ⪢ ωBe) which, together with plasma non-isothermality (Te ⪢ Ti), sets conditions typical for laboratory and space plasmas. At present, the processes under these conditions have not been adequately investigated, either experimentally or theoretically, especially for our case of developed Langmuir turbulence, when the spatial and temporal scales far exceed those for a single caviton. This work is centred on the study of developed Langmuir turbulence in a magnetized plasma.
{"title":"Investigation of Langmuir turbulence excited by a relativistic electron beam in a magnetic field","authors":"L.N. Vyacheslavov, V.S. Burmasov, I.V. Kandaurov, Eh.P. Kruglyakov, O.I. Meshkov, A.L. Sanin","doi":"10.1016/0021-9169(95)00132-8","DOIUrl":"10.1016/0021-9169(95)00132-8","url":null,"abstract":"<div><p>The Thomson scattering technique has been employed for the observation of turbulent waves excited by a relativistic electron beam. The frequency and <em>k</em>-spectra of the Langmuir waves are measured both in the excited and damped regions. The waves interact directly with the beam electrons inside a narrow section of <em>k</em>-sppace amid the region occupied by the non-resonant waves, which concentrate near <em>k</em> ∼ <em>ω</em><sub>pe</sub>/<em>c</em>. Both resonant and non-resonant waves hold equal (to within an order of magnitude) amounts of energy. Incoherent scattering of the second harmonic of a Nd : glass laser is used to measure the time history of the electron distribution function including the super thermal tails. The typical beam and plasma parameters are as follows: (<em>n</em>e ∼ 10<sup>15</sup> cm<sup>−3</sup>, <em>n</em><sub>b</sub>/<em>n</em><sub>e</sub> ∼ 10<sup>−4</sup>, <em>B</em> = 1–4 T, <em>t</em><sub>b</sub> = 100–200 <em>ns</em>). The peculiarity of these experiments is the presence of a strong magnetic field (<em>ω</em><sub>Be</sub><em>c</em>/<em>ω</em><sub>pe</sub> <em>V</em><sub>Te</sub> ⪢ 1, <em>but</em> <em>cope</em> ⪢ <em>ω</em><sub>Be</sub>) which, together with plasma non-isothermality (<em>T</em><sub>e</sub> ⪢ <em>T</em><sub>i</sub>), sets conditions typical for laboratory and space plasmas. At present, the processes under these conditions have not been adequately investigated, either experimentally or theoretically, especially for our case of developed Langmuir turbulence, when the spatial and temporal scales far exceed those for a single caviton. This work is centred on the study of developed Langmuir turbulence in a magnetized plasma.</p></div>","PeriodicalId":100754,"journal":{"name":"Journal of Atmospheric and Terrestrial Physics","volume":"58 8","pages":"Pages 1005-1012"},"PeriodicalIF":0.0,"publicationDate":"1996-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0021-9169(95)00132-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"53071731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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