Hydroxyl in the stratosphere and mesosphere – Part 1: Diurnal variability

Minschwaner, K.; Manney, G. L.; Wang, S. H.; Harwood, R. S.

doi:10.5194/acp-11-955-2011

Cited by 21 publications

(14 citation statements)

References 26 publications

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“…This is consistent with our initial assumption regarding injecting in a location where fewer aerosols from the previous year are present. Chemical characteristics of the stratosphere at the time of the injection (in particular OH, which oxidizes SO 2 ), which are heavily dependent on the solar zenith angle (Minschwaner et al, 2011), do not appear to correlate with the resulting SO 4 burden (not shown), indicating that the produced AOD is mostly a function of the transport efficiency.…”

Section: Stratospheric Aerosolmentioning

confidence: 99%

Seasonal Injection Strategies for Stratospheric Aerosol Geoengineering

Visioni

MacMartin

Kravitz

et al. 2019

Geophysical Research Letters

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Simulations of stratospheric aerosol geoengineering have typically considered injections at a constant rate over the entire year. However, the seasonal variability of both sunlight and the stratospheric circulation suggests seasonally dependent injection strategies. We simulated single‐point injections of the same amount of SO2 in each of the four seasons and at five different latitudes (30°S, 15°S, equator, 15°N, and 30°N), 5 km above the tropopause. Our findings suggest that injecting only during one season reduces the amount of SO2 needed to achieve a certain aerosol optical depth, thus potentially reducing some of the side effects of geoengineering. We find, in particular, that injections at 15°N or 15°S in spring of the corresponding hemisphere results in the largest reductions in incoming solar radiation. Compared to annual injections, by injecting in the different seasons we identify additional distinct spatiotemporal aerosol optical depth patterns, thanks to seasonal differences in the stratospheric circulation.

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Section: Stratospheric Aerosolmentioning

confidence: 99%

Seasonal Injection Strategies for Stratospheric Aerosol Geoengineering

Visioni

MacMartin

Kravitz

et al. 2019

Geophysical Research Letters

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“…Therefore, atmospheric transport of HO x below 80 km is negligible. For OH, seasonal and solar cycle variability is connected to solar activity together with the seasonal variation of water vapor and ozone in the mesosphere [ Canty and Minschwaner , 2002] whereas the diurnal variability of OH is related to the solar zenith angle (SZA) variation during the day and can be characterized by exponential functions of the secant of SZA [ Minschwaner et al , 2011].…”

Section: Introductionmentioning

confidence: 99%

Precipitating radiation belt electrons and enhancements of mesospheric hydroxyl during 2004–2009

et al. 2012

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[1] Energetic particle precipitation leads to enhancement of odd hydrogen (HO x ) below 80 km altitude through water cluster ion chemistry. Using measurements from the Microwave Limb Sounder (MLS/Aura) and Medium Energy Proton and Electron Detector (MEPED/POES) between 2004-2009, we study variations of nighttime OH caused by radiation belt electrons at geomagnetic latitudes [55][56][57][58][59][60][61][62][63][64][65] . For those months with daily mean 100-300 keV electron count rate exceeding 150 counts/s in the outer radiation belt, we find a strong correlation (r ≥ 0.6) between OH mixing ratios at 70-78 km (0.046-0.015 hPa) and precipitating electrons. Correlations r ≥ 0.35, corresponding to random chance probability p ≤ 5%, are observed down to52 km (0.681 hPa), while no clear correlation is observed at altitudes below. This suggests that the fluxes of ≥3 MeV electrons were not high enough to cause observable changes in OH mixing ratios. At 75 km, in about 34% of the 65 months analyzed we find a correlation r ≥ 0.35. Although similar results are obtained for both hemispheres in general, in some cases the differences in atmospheric conditions make the OH response more difficult to detect in the South. Considering the latitude extent of electron forcing, we find clear effects on OH at magnetic latitudes [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] , while the lower latitudes are influenced much less. Because the time period 2004-2009 analyzed here coincided with an extended solar minimum, and the year 2009 was anomalously quiet, it is reasonable to assume that our results provide a lower-limit estimation of the importance of energetic electron precipitation at the latitudes considered.

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“…The response was also found in the observed data. The diurnal cycle of OH concentration which reflects a solar zenith angle changes was analyzed by Minschwaner et al (2011). The response of OH from Fritz Peak Observatory (Colorado) to 11-yr solar cycle was reported by Canty and Minschwaner (2002).…”

Section: Introductionmentioning

confidence: 99%

Signature of the 27-day solar rotation cycle in mesospheric OH and H<sub>2</sub>O observed by the Aura Microwave Limb Sounder

et al. 2012

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Abstract. The mesospheric hydroxyl radical (OH) is mainly produced by the water vapor (H 2 O) photolysis and could be considered as a proxy for the influence of the solar irradiance variability on the mesosphere. We analyze the tropical mean response of the mesospheric OH and H 2 O data as observed by the Aura Microwave Limb Sounder (MLS) to 27-day solar variability. The analysis is performed for two time periods corresponding to the different phases of the 11-yr cycle: from December 2004 to December 2005 (the period of "high activity" with a pronounced 27-day solar cycle) and from August 2008 to August 2009 ("solar minimum" period with a vague 27-day solar cycle). We demonstrate, for the first time, that in the mesosphere the daily time series of OH concentrations correlate well with the solar irradiance (correlation coefficients up to 0.79) at zero time-lag. At the same time H 2 O anticorrelates (correlation coefficients up to −0.74) with the solar irradiance at non-zero time-lag. We found that the response of OH and H 2 O to the 27-day variability of the solar irradiance is strong for the period of the high solar activity and negligible for the solar minimum conditions. It allows us to suggest that the 27-day cycle in the solar irradiance and in OH and H 2 O are physically connected.

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Hydroxyl in the stratosphere and mesosphere – Part 1: Diurnal variability

Cited by 21 publications

References 26 publications

Seasonal Injection Strategies for Stratospheric Aerosol Geoengineering

Seasonal Injection Strategies for Stratospheric Aerosol Geoengineering

Precipitating radiation belt electrons and enhancements of mesospheric hydroxyl during 2004–2009

Signature of the 27-day solar rotation cycle in mesospheric OH and H<sub>2</sub>O observed by the Aura Microwave Limb Sounder

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Hydroxyl in the stratosphere and mesosphere – Part 1: Diurnal variability

Cited by 21 publications

References 26 publications

Seasonal Injection Strategies for Stratospheric Aerosol Geoengineering

Seasonal Injection Strategies for Stratospheric Aerosol Geoengineering

Precipitating radiation belt electrons and enhancements of mesospheric hydroxyl during 2004–2009

Signature of the 27-day solar rotation cycle in mesospheric OH and H&lt;sub&gt;2&lt;/sub&gt;O observed by the Aura Microwave Limb Sounder

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Signature of the 27-day solar rotation cycle in mesospheric OH and H<sub>2</sub>O observed by the Aura Microwave Limb Sounder