Variations in the free chlorine content of the stratosphere (1991–1997): Anthropogenic, volcanic, and methane influences

Froidevaux, L.; Waters, J. W.; Read, W. G.; Connell, Peter S.; Kinnison, D. E.; Russell, James M.

doi:10.1029/1999jd901039

Cited by 23 publications

(22 citation statements)

References 39 publications

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“…Thus the pattern of steeper slopes for lower CH 4 is robust across both Nedoluha et al's and our analyses. This is precisely the pattern one would expect for the inverse power relationships discussed by Froidevaux et al (2000). Thus the present SOFIE/MLS comparison is consistent with studies using both UARS and ground-based data that showed ClO and CH 4 in the upper stratosphere varying with a high degree of anticorrelation.…”

Section: Atmossupporting

confidence: 79%

“…For example, documented an increase in upper stratospheric ClO during the early years of the Upper Atmospheric Research Satellite (UARS) mission which was explained as a direct consequence of the decrease in CH 4 observed by Nedoluha et al (1998). Froidevaux et al (2000) observed a general anticorrelation between variations in ClO and CH 4 at 2 hPa in the tropics. They showed that there should be an inverse relationship between ClO and CH 4 .…”

Section: Chlorine Monoxide (Clo)mentioning

confidence: 99%

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Persistence of upper stratospheric wintertime tracer variability into the Arctic spring and summer

et al. 2016

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Abstract. Using data from the Aeronomy of Ice in the Mesosphere (AIM) and Aura satellites, we have categorized the interannual variability of winter-and springtime upper stratospheric methane (CH 4 ). We further show the effects of this variability on the chemistry of the upper stratosphere throughout the following summer. Years with strong wintertime mesospheric descent followed by dynamically quiet springs, such as 2009, lead to the lowest summertime CH 4 . Years with relatively weak wintertime descent, but strong springtime planetary wave activity, such as 2011, have the highest summertime CH 4 . By sampling the Aura Microwave Limb Sounder (MLS) according to the occultation pattern of the AIM Solar Occultation for Ice Experiment (SOFIE), we show that summertime upper stratospheric chlorine monoxide (ClO) almost perfectly anticorrelates with the CH 4 . This is consistent with the reaction of atomic chlorine with CH 4 to form the reservoir species, hydrochloric acid (HCl). The summertime ClO for years with strong, uninterrupted mesospheric descent is about 50 % greater than in years with strong horizontal transport and mixing of high CH 4 air from lower latitudes. Small, but persistent effects on ozone are also seen such that between 1 and 2 hPa, ozone is about 4-5 % higher in summer for the years with the highest CH 4 relative to the lowest. This is consistent with the role of the chlorine catalytic cycle on ozone. These dependencies may offer a means to monitor dynamical effects on the high-latitude upper stratosphere using summertime ClO measurements as a proxy. Additionally, these chlorine-controlled ozone decreases, which are seen to maximize after years with strong uninterrupted wintertime descent, represent a new mechanism by which mesospheric descent can affect polar ozone. Finally, given that the effects on ozone appear to persist much of the rest of the year, the consideration of winter/spring dynamical variability may also be relevant in studies of ozone trends.

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Section: Atmossupporting

confidence: 79%

Section: Chlorine Monoxide (Clo)mentioning

confidence: 99%

Persistence of upper stratospheric wintertime tracer variability into the Arctic spring and summer

et al. 2016

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“…The datasets are being used for various other kinds of study; e.g. deriving trends in CH 4 in the stratosphere, timeseries correlation of CH 4 with other constituents such as ClO x , and also to create four dimensional regular grid tracer distributions (Froidevaux et al, 2000;Patra and Santhanam, 2001) It is apparent from the diagram that depending on dynamical condition in our study region, the characteristics of the vertical profiles change from year to year. For instance, the 1997 and 2001 profiles show clear deviation from the other profiles by an amount larger than the error bars, and also the altitude of maximum deviation lies in the range of 25-35 km.…”

Section: Data and Analysismentioning

confidence: 99%

Halogen Occultation Experiment (HALOE) and balloon-borne in situ measurements of methane in stratosphere and their relation to the quasi-biennial oscillation (QBO)

et al. 2003

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Abstract. Measurements of methane have been made from various observational platforms in the atmosphere. In this article, we have compared four high precision balloon-borne measurements from Hyderabad (17.5 • N), India in the period of 1987 and 1998 with a part of HALOE/UARS global observations available since 1991. All the balloon measurements correspond to boreal spring (March and April) but belong to different years. A comparison shows fairly good agreement with each other. The gradient in CH 4 profiles in the troposphere is controlled by the variation in vertical transport. The strongest effect of dynamical influence on methane vertical profiles is shown to be resulting from the dynamical quasi-biennial oscillation in the stratosphere, and that has been consistently derived from both the measurement techniques and chemistry-transport model simulations. It is observed that the QBO signal in CH 4 anomaly exhibits interhemispheric asymmetry caused by the tropics to midlatitude circulation in the stratosphere. A mechanism is suggested to explain how and to what extent the methane vertical profiles over Hyderabad and higher latitudes could be modulated by the prevailing QBO winds in the tropics. We have also discussed how the same mechanism would affect ozone distribution in the stratosphere quite differently.

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“…The reaction of atomic chlorine with methane sequesters active chlorine in the HCl reservoir (Siskind et al, 1998). Thus, an anticorrelation of active chlorine and methane is expected and has indeed been observed in the upper stratosphere by Froidevaux et al (2000), using UARS-MLS ClO and UARS-HALOE methane.…”

Section: Middle and Low Latitudesmentioning

confidence: 99%

Chlorine in the stratosphere

Clarmann¹

2013

Atmósfera

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Este artículo reseña varios aspectos de los compuestos clorados presentes en la estratosfera, que incluyen tanto su papel como agentes químicos como su función de trazadores de los procesos dinámicos. En la estratosfera, el cloro reactivo se libera a partir de los clorofluorocarbonos y otros gases orgánicos que contienen cloro. La mayor parte del cloro reactivo se convierte en compuestos inertes que almacenan cloro, como ClONO 2 y HCl. La reactivación del cloro estratosférico ocurre principalmente por reacciones heterogéneas en vórtices polares invernales, en combinación con la luz solar. Los ciclos catalíticos de Cl, ClO, BrO, Cl 2 O 2 , ClO 2 y otros compuestos como NO, NO 2 , OH y HO 2 destruyen el oxígeno impar (ozono y oxígeno atómico) de la atmósfera. El ciclo del dímero de ClO es particularmente importante en la formación del agujero de ozono, mientras que en latitudes medias el HOCl tiene alguna relevancia. También los eventos de protones solares pueden alterar la química del cloro estratosférico, aunque su efecto de activación o desactivación depende de las condiciones de iluminación. La vida media atmosférica de los clorofluorocarbonos determina la disponibilidad de las sustancias que destruyen el ozono en la estratosfera y depende de la circulación de Brewer-Dobson, que a su vez establece a qué altitudes y por cuánto tiempo está expuesta una porción de aire a la fotoquímica. Por su parte, los gases orgánicos clorados pueden usarse como trazadores para estimar la edad del aire estratosférico y así examinar la circulación de Brewer-Dobson. El uso de métodos complementarios de medición ha sido esencial para ampliar nuestros conocimientos sobre los compuestos clorados en la estratosfera. El ClO se mide principalmente con métodos de percepción remota en las regiones del infrarrojo y de microondas. Las bandas del infrarrojo lejano son ideales para medir el HOCl, pero también se encuentra información sustancial en las regiones de microondas y del infrarrojo medio. El ClONO 2 se mide sólo en el infrarrojo térmico, en tanto que el HCl se puede observar en las regiones de microondas y del infrarrojo lejano y medio. Sin embargo, las bandas del HCl en el infrarrojo medio se encuentran en longitudes de onda en que la radiación de cuerpo negro a temperaturas terrestres es tan baja que el HCl sólo se puede detectar mediante la técnica de absorción solar. Los clorofluorocarbonos se miden con mayor exactitud utilizando métodos de muestreo in situ, aunque para lograr una cobertura global se requieren mediciones en el infrarrojo térmico realizadas desde satélites. En términos epistemológicos, la investigación de la química de la estratosfera y el papel específico de los compuestos clorados se ha basado en distintos conceptos científicos como el razonamiento deductivo, el falsacionismo, el razonamiento abductivo y la llamada "solución de enigmas dentro de la ciencia normal". Sin embargo, la concepción estructuralista de la visión no enunciativa de las teorías es probablemente la que mejor se aplica a la investigación de ...

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Variations in the free chlorine content of the stratosphere (1991–1997): Anthropogenic, volcanic, and methane influences

Cited by 23 publications

References 39 publications

Persistence of upper stratospheric wintertime tracer variability into the Arctic spring and summer

Persistence of upper stratospheric wintertime tracer variability into the Arctic spring and summer

Halogen Occultation Experiment (HALOE) and balloon-borne in situ measurements of methane in stratosphere and their relation to the quasi-biennial oscillation (QBO)

Chlorine in the stratosphere

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