المؤلفون: Joshi, Vaidehi, Sharma, Som, Kumar, Kondapalli Niranjan, Patel, Nisha, Kumar, Prashant, Bencherif, Hassan, Ghosh, Priyanka, Jethva, Chintan, Vaishnav, Rajesh

المصدر: Climate Dynamics; Feb2020, Vol. 54 Issue 3/4, p2481-2492, 12p

مصطلحات موضوعية: MIDDLE atmosphere, MESOSPHERE, ATMOSPHERIC tides, THERMOSPHERE, TIME series analysis

مستخلص: The present study focuses on the middle atmospheric ozone variability using 14 (2002–2015) years of Sounding of the Atmosphere using Broadband Emission Radiometry onboard Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite observations over the mid-latitude regions of northern and southern hemispheres. It is noted that ozone buildup starts late winter, and peaks during the springtime and gradually decreases in summer to autumn transitional period in both the hemispheres. The time series of ozone indicates the dominant annual and semi-annual oscillations in the middle atmosphere. The annual oscillation (AO) is found to be dominant over both the hemispheres, while the semi-annual oscillation (SAO) peaks at two different altitude regions: 30–60 km and 80–100 km. Further, the amplitude of AO is much significant than SSAO and MSAO. It is also noted another significant oscillation that peaks at ~ 4 months in the altitude range 60–80 km. The strength of these oscillations at different sites is studied by comparing it with the zonal mean spectrum to assess the longitudinal asymmetry. It is found that the longitudinal asymmetry is more significant in the northern hemisphere than the southern hemisphere. This can be attributed to the differences in the land (elevated topographies in the northern hemisphere) and primarily ocean (in southern hemisphere) contrast that further contributes to the differences in the strength of the vertically propagating planetary-scale waves modulating the middle atmospheric ozone. [ABSTRACT FROM AUTHOR]

: Copyright of Climate Dynamics is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Sharma, Som, Kumar, Prashant, Jethva, Chintan, Vaishnav, Rajesh, Bencherif, Hassan

المصدر: Climate Dynamics; Jun2017, Vol. 48 Issue 11/12, p3671-3684, 14p

مصطلحات موضوعية: ATMOSPHERIC tides, ATMOSPHERIC temperature, RADIOMETRY, ATMOSPHERIC structure, TROPICAL climate

مصطلحات جغرافية: SOUTHERN Hemisphere, NORTHERN Hemisphere

مستخلص: The temperature retrieved from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) onboard Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite during January 2002 to September 2015 are used in this study to delineate the differences of middle atmospheric thermal structure in the Northern Hemisphere (NH) and Southern Hemisphere (SH). Two stations namely Mt. Abu (24.59°N, 72.70°E) in NH and Reunion Island (21.11°S, 55.53°E) in SH are chosen over sub-tropical regions. Temperature climatology from SABER observations suggests that stratopause is warmer, and upper mesosphere is cooler in NH as compared to SH. Three atmospheric models are used to understand the monthly thermal structure differences for different altitudes. Moreover, semi-annual, annual and quasi-biennial oscillations are studied using Lomb Scargle Periodogram and Wavelet transform techniques. Over NH, summer and winter season are warmer (~4 K) and cooler (~3 K) respectively in stratosphere as compared to SH. It is important to note here that Mt. Abu temperature is warmer (~9 K) than Reunion Island in winter but in summer season Mt. Abu temperature is cooler in upper mesosphere and above mesosphere NH shows warming. Results show that annual oscillations are dominated in both hemisphere as compared to semi-annual and quasi-biennial oscillations. In upper mesosphere, strength of annual oscillations is substantial in NH, while semi-annual oscillations are stronger in SH. Wavelet analyses found that annual oscillations are significant in NH near mesopause, while semi-annual oscillations are strengthening in SH. [ABSTRACT FROM AUTHOR]

: Copyright of Climate Dynamics is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)