Study on oxygen atmospheric band dayglow: global and seasonal variations deduced from high-resolution Doppler imager observations

Ratnam, M. Venkat; Shen, Chia-Jou; Chen, Wei-Nai; Nee, J. B.

doi:10.1016/j.jastp.2003.10.009

Cited by 7 publications

(4 citation statements)

References 31 publications

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“…Although a few reports based on satellite observations are available, they all dealt with the global coverage and not so much on the mesopause over low‐latitude locations. Using HRDI/UARS data, Thulasiraman and Nee [2002] and Venkat Ratnam et al [2004] observed that the mesopause altitude for the present location is around 97 km with a temperature of 180 K. The distributions of mesopause height and temperature vary in the range of 96–100 km and 165–175 K, respectively. Although the distribution of mesopause altitude and temperatures have been shown by Kishore Kumar et al [2008] using SABER data from 2007, in the present study, we have emphasized the variabilities related to both mesopause and secondary minima using a larger database (2002–2008).…”

Section: Resultsmentioning

confidence: 61%

“…These temperature inversions (TIs) are mainly attributed to upward propagating tides and gravity waves [ Meriwether and Gardner , 2000]. Stronger temperature inversions are mainly seen during equinox months followed by summer, and minimum temperature inversions are seen during winter over Gadanki [ Venkat Ratnam et al , 2004; Kishore Kumar et al , 2008]. Furthermore, it was shown that thermal (diurnal) tides (vertical wavelengths of 10–15 km) are strong enough to produce the temperature inversions in the tropical latitudes (±30°) [ Gurubaran et al , 2005].…”

Section: Resultsmentioning

confidence: 99%

“…From a preliminary study of the High Resolution Doppler Imager (HRDI) temperature data, Ortland et al [1998] reported the two-level mesopause. Using HRDI data, further evidence of two-level mesopause has been provided by Thulasiraman and Nee [2002] and with a larger data set by Venkat Ratnam et al [2004]. It is generally accepted that in the MLT region, besides radiative processes, other mechanisms such as dynamical (through momentum deposition by tides/ gravity waves) and chemical (through exothermic reactions) processes provide substantial contribution to the energy budget.…”

Section: Introductionmentioning

confidence: 94%

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Tropical mesopause: Is it always close to 100 km?

Ratnam

Patra

Murthy³

2010

J. Geophys. Res.

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[1] Global distribution of mesopause using observations of Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) aboard the Thermosphere-IonosphereMesosphere Energetics and Dynamics satellite is studied with special emphasis on tropical latitudes. Temperature structure of the mesosphere and lower thermosphere over Gadanki (13.5°N, 79.2°E), a tropical latitude location in India, has been studied in detail. The mesopause altitude at Gadanki is observed to be in the range of 87-105 km with a mean of ∼98 km, and the temperature is in the range of 160-205 K with a mean of ∼170 K. A secondary temperature minimum is observed in the height region of 75-80 km with temperature in the range of 175-195 K. Although the mesopause temperature and altitude show pronounced short-term variability, on a seasonal mean basis, the variation in these two parameters is rather small. There is no significant long-term variation in mesopause altitude. The height of the secondary minimum, however, is found to show semiannual variation with a maximum in solstices and a minimum in equinoxes. Thus, the variabilities in the height and temperature of the mesopause and the secondary minimum reported here are different from the two-level mesopause reported previously for middle and high latitudes. Another significant result that comes from the time series analysis of mesopause temperature is a decreasing trend with a rate of ∼0.72 ± 0.05 K/yr. Furthermore, the long-term mean profile of temperature does not show the secondary minimum, providing strong support that it could be due to shorter scale tides and gravity waves. The possible implications of the mesopause temperature structure on various physical processes occurring in the mesosphere and the lower thermosphere are discussed.

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Section: Resultsmentioning

confidence: 61%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

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Tropical mesopause: Is it always close to 100 km?

Ratnam

Patra

Murthy³

2010

J. Geophys. Res.

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“…Using shipborne lidar measurements during April–July 1996, von Zahn et al [1996] showed that there are two distinct levels of MP altitude on the global scale and that MP was lower (86 ± 3 km) and cooler (150–170 K) in the northern midlatitudes and high latitudes and higher (100 ± 3 km) and warmer (160–190 K) at the other latitudes. Investigation of temperature data for MP characteristics from the High Resolution Doppler Imager (HRDI) instrument onboard the UARS satellite also revealed a lower and cooler MP during summer and a higher and warmer MP in winter [ Thulasiraman and Nee , 2002; Venkat Ratnam et al , 2004]. Xu et al [2007] also got the same results for MP characteristics using the observations of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) onboard the Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics (TIMED) satellite during 2002–2006.…”

Section: Introductionmentioning

confidence: 88%

The temperature structure of the mesosphere over Taiwan and comparison with other latitudes

Das

Chen

2011

J. Geophys. Res.

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[1] We present here a detailed investigation of the mesospheric temperature structure over Taiwan, a subtropical location, using 9 years of observations (March 2002 to October 2010 by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. The mesopause (MP) is always found to be located at a higher level with a mean altitude of 98.2 ± 1.8 km and mean temperature of 165.0 ± 5.8 K. The climatological study shows that MP is lower and warmer during summer and higher and cooler during winter, which is different from the midlatitudes and high latitudes as well as from low latitudes. The temperatures of the mesospheric temperature inversions (MTI) and secondary minimum (SM), on the other hand, are lower during summer and higher during winter, and their altitudes do not show any annual variation. It is found that the thermal structure over Taiwan undergoes a phase shift between 89 and 95 km, and above this region it is in phase with the solar flux. Since MP is always above these altitudes, it shows a seasonal variation that is in phase with the solar energy inputs, and the temperatures below (that of MTI and SM) show the opposite seasonal variation caused by mesospheric adiabatic cooling and warming processes.

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Global distribution of pauses observed with satellite measurements

Ratnam

Kishore

2013

J Earth Syst Sci

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Several studies have been carried out on the tropopause, stratopause, and mesopause (collectively termed as 'pauses') independently; however, all the pauses have not been studied together. We present global distribution of altitudes and temperatures of these pauses observed with long-term space borne highresolution measurements of Global Positioning System (GPS) Radio Occultation (RO) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) aboard Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. Here we study the commonality and differences observed in the variability of all the pauses. We also examined how good other datasets will represent these features among (and in between) different satellite measurements, re-analysis, and model data. Hemispheric differences observed in all the pauses are also reported. In addition, we show that asymmetries between northern and southern hemispheres continue up to the mesopause. We analyze inter and intra-seasonal variations and long-term trends of these pauses at different latitudes. Finally, a new reference temperature profile is shown from the ground to 110 km for tropical, mid-latitudes, and polar latitudes for both northern and southern hemispheres.

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Study on oxygen atmospheric band dayglow: global and seasonal variations deduced from high-resolution Doppler imager observations

Cited by 7 publications

References 31 publications

Tropical mesopause: Is it always close to 100 km?

Tropical mesopause: Is it always close to 100 km?

The temperature structure of the mesosphere over Taiwan and comparison with other latitudes

Global distribution of pauses observed with satellite measurements

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