Seasonal, interannual and long-term variabilities and tendencies of water vapour in the upper stratosphere and mesospheric region over tropics (30°N-30°S)

Nath, Oindrila; Sridharan, S.; Naidu, C. V.

doi:10.1016/j.jastp.2017.07.009

Cited by 9 publications

(11 citation statements)

References 22 publications

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“…Average Halogen Occultation Experiment H 2 O response profiles for the latitude region of 30°S to 30°N for comparison with those reported by Nath, Sridharan, and Naidu () from the Microwave Limb Sounder. Horizontal bars are at selected levels for the semiannual oscillation (SAO), annual oscillation (AO), El‐Nino/Southern Oscillation (ENSO), and Lya terms, and they indicate ±1 σ values in each instance.…”

Section: Comparisons With Previous Analyses Of H2omentioning

confidence: 85%

“…There is also a notable difference in the H 2 O responses to ENSO for the uppermost mesosphere. Nath, Sridharan, and Naidu () report a significant positive response of 0.1 ppmv/MEI at 0.01 hPa. Instead, the HALOE results in Figure show a near zero value for the coefficient of that term, although it is not significant and not for the same span of years.…”

Section: Comparisons With Previous Analyses Of H2omentioning

confidence: 98%

“…Instead, the HALOE results in Figure show a near zero value for the coefficient of that term, although it is not significant and not for the same span of years. Again, such differences for the tropics at 0.01 hPa may be because we consider all terms in our MLR analysis, while Nath, Sridharan, and Naidu () analyzed deseasonalized MLS data time series.…”

Section: Comparisons With Previous Analyses Of H2omentioning

confidence: 99%

“…Remsberg (2010) reported on the seasonal and longer-term variations of H 2 O in the mesosphere based on data from the Halogen Occultation Experiment (HALOE) instrument (Grooss & Russell, 2005;Russell et al, 1993) that operated aboard the Upper Atmosphere Research Satellite and for diagnosing the performance of the radiative-chemical-transport models. Results of a similar study for the low latitudes are in Nath, Sridharan, and Naidu (2018), based on H 2 O from the Microwave Limb Sounder (MLS) of the Aura satellite. The present study is a reanalysis of the HALOE H 2 O time series with the goal of quantifying its responses to dynamical and solar cycle forcings throughout the mesosphere and for comparison with the results from MLS.…”

Section: Introductionmentioning

confidence: 99%

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Observed Responses of Mesospheric Water Vapor to Solar Cycle and Dynamical Forcings

et al. 2018

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This study focuses on responses of mesospheric water vapor (H2O) to the solar cycle flux at Lyman‐α wavelength and to dynamical forcings according to the multivariate El‐Nino/Southern Oscillation (ENSO) index. The zonal‐averaged responses are for latitudes from 60°S to 60°N and pressure‐altitudes from 0.01 to 1.0 hPa, as obtained from multiple linear regression analyses of time series of H2O from the Halogen Occultation Experiment for July 1992 to November 2005. The results compare very well with those from a separate simultaneous temporal and spatial (STS) method that also confirms that there are no significant sampling biases affecting both sets of results. Distributions of the seasonal amplitudes for temperature and H2O are in accord with the seasonal net circulation. In general, the responses of H2O to ENSO are anticorrelated with those of temperature. H2O responses to multivariate ENSO index are negative in the upper mesosphere and largest in the Northern Hemisphere; responses in the lower mesosphere are more symmetric with latitude. H2O responses to the Lyman‐α flux (Lya) vary from strong negative values in the uppermost mesosphere to very weak, positive values in the tropical lowermost mesosphere. However, the effects of those H2O responses to the solar activity extend to the rest of the mesosphere via dynamical processes. Profiles of the responses to ENSO and Lya also agree reasonably with published results for H2O at the low latitudes from the Microwave Limb Sounder.

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Section: Comparisons With Previous Analyses Of H2omentioning

confidence: 85%

Section: Comparisons With Previous Analyses Of H2omentioning

confidence: 98%

Section: Comparisons With Previous Analyses Of H2omentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observed Responses of Mesospheric Water Vapor to Solar Cycle and Dynamical Forcings

et al. 2018

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“…Global warming is predicted to increase tropospheric lightning activity (5–10% for every 1° of warming) (Krause et al, ; Michalon et al, ; Price & Rind, ; Romps et al, ; Trapp et al, ) although the prediction has a large uncertainty in the lightning parameterization (Finney et al, ). Long‐term trends of increase in mesospheric carbon dioxide (CO

_{2}

) and water vapor (H

_{2}

O) have been reported owing to recent improvement in the accuracy of global measurements (Chandra et al, ; Nath et al, ; Nedoluha et al, ; Qian et al, ). These trends, approximately +5.5% of CO

_{2}

and

<

10% of H

_{2}

O per decade, are related to anthropogenic CO

_{2}

and methane (CH

_{4}

) emissions, respectively, and affect radiative forcing and mesospheric composition.…”

Section: Estimation Of Ho 2 Amount Produced By Sprite Eventsmentioning

confidence: 99%

HO Generation Above Sprite‐Producing Thunderstorms Derived from Low‐Noise SMILES Observation Spectra

Yamada

Sato

Adachi³

et al. 2020

Geophysical Research Letters

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No direct observational evidence of sprite‐produced active radicals has been presented owing to the difficulty of observing a small event area in the nighttime mesosphere, whereas sprite chemical models have indicated that sprite discharge locally affects the atmospheric composition. We present the first observational evidence of a HO 2 production above sprite‐producing thunderstorms from the coincidence of temporal‐spatial observations of HO 2 spectra, sprite events, and thunderstorms by two space instruments, a submillimeter‐wave limb spectrometer and ultraviolet/visible Imager and a ground‐based very low frequency radiation lightning detection network. A total of three areas was identified with enhanced HO 2 levels of approximately 10 25 molecules. A chemical sprite model indicates an increase in HO 2 in the considered altitude region; however, the predicted production due to a single sprite event is smaller than the observed enhancement. Our observational results suggest that sprites potentially contribute 1% of nighttime background HO 2 generation at altitudes of 75–80 km globally.

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Long‐Term Trends in the Upper Atmosphere

Laštovička

2021

Geophysical Monograph Series

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Seasonal, interannual and long-term variabilities and tendencies of water vapour in the upper stratosphere and mesospheric region over tropics (30°N-30°S)

Cited by 9 publications

References 22 publications

Observed Responses of Mesospheric Water Vapor to Solar Cycle and Dynamical Forcings

Observed Responses of Mesospheric Water Vapor to Solar Cycle and Dynamical Forcings

HO Generation Above Sprite‐Producing Thunderstorms Derived from Low‐Noise SMILES Observation Spectra

Long‐Term Trends in the Upper Atmosphere

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