Aircraft‐Based Observations of Ozone‐Depleting Substances in the Upper Troposphere and Lower Stratosphere in and Above the Asian Summer Monsoon

Adcock, Karina E.; Fraser, Paul J.; Hall, B. D.; Langenfelds, Ray L.; Lee, Geoffrey; Montzka, S. A.; Oram, D. E.; Röckmann, Thomas; Stroh, F.; Sturges, William T.; Vogel, Bärbel; Laube, Johannes C.

doi:10.1029/2020jd033137

Cited by 22 publications

(18 citation statements)

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“…VSLS have been found to make an important contribution to stratospheric halogen loading and thus polar ozone destruction (World Meteorological Organization [WMO], 2018). Airborne in situ measurements in the ASM convective transport region during the StratoClim campaign found much higher than the previously estimated background concentrations (by ∼ a factor of 2) of Chlorinated VSLS at the tropopause level (Adcock et al., 2021), providing observational evidence that the ASM is an important source region for halogenated VSLS (Engel et al., 2018). The contribution of ASM transport to stratospheric ozone chemistry is an important motivation for characterizing this transport pathway in ACCLIP.…”

Section: Vertical Structure and The Depth Of The Asm Transport Into S...mentioning

confidence: 79%

“…Also planned are balloon‐borne measurements of aerosol and water vapor profiles to complement the airborne studies. This project follows and complements the Stratospheric and upper tropospheric processes for better Climate predictions (StratoClim; http://www.stratoclim.org/) project, which conducted high‐altitude research flights from Kathmandu, Nepal, and successfully sampled chemical distributions of a suite of trace gases and aerosols near the center of the ASM anticyclone during July–August 2017 (Adcock et al., 2021; Bucci et al., 2020; Höpfner et al., 2019; Mahnke et al., 2021; von Hobe et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

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A Multimodel Investigation of Asian Summer Monsoon UTLS Transport Over the Western Pacific

et al. 2022

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The Asian summer monsoon (ASM) as a chemical transport system is investigated using a suite of models in preparation for an airborne field campaign over the Western Pacific. Results show that the dynamical process of anticyclone eddy shedding in the upper troposphere rapidly transports convectively uplifted Asian boundary layer air masses to the upper troposphere and lower stratosphere over the Western Pacific. The models show that the transported air masses contain significantly enhanced aerosol loading and a complex chemical mixture of trace gases that are relevant to ozone chemistry. The chemical forecast models consistently predict the occurrence of the shedding events, but the predicted concentrations of transported trace gases and aerosols often differ between models. The airborne measurements to be obtained in the field campaign are expected to help reduce the model uncertainties. Furthermore, the large‐scale seasonal chemical structure of the monsoon system is obtained from modeled carbon monoxide, a tracer of the convective transport of pollutants, which provides a new perspective of the ASM circulation, complementing the dynamical characterization of the monsoon.

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Section: Vertical Structure and The Depth Of The Asm Transport Into S...mentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

A Multimodel Investigation of Asian Summer Monsoon UTLS Transport Over the Western Pacific

et al. 2022

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“…The post-flight spectral analysis of the collected data for the detection of O 3 , NO 2 , and BrO is based on the DOAS method (differential optical absorption spectroscopy; Platt and Stutz, 2008). For the UV spectrometer retrieval of BrO differential slant column densities (dSCD), given in molecules per square centimeter, a fit window of 346−359 nm is used as suggested by Aliwell et al (2002), i.e., a two-band fit of the vibrational transitions 4.0 and 5.0 of the A 2 3/2 ← X 2 3/2 electronic transition (Wilmouth et al, 1999). For O 3 -UV dSCDs, used as the corresponding scaling gas, a fit window of 338−357 nm is applied (Puk , īte and Wagner, 2016).…”

Section: Mini-doas Measurements Of O 3 No 2 and Bromentioning

confidence: 99%

“…Spectral retrieval absorption cross sections used for the DOAS method analysis (Hüneke et al, 2017;Stutz et al, 2017). The solar I 0 correction used is suggested in Aliwell et al (2002).…”

Section: Mini-doas Measurements Of O 3 No 2 and Bromentioning

confidence: 99%

Organic and inorganic bromine measurements around the extratropical tropopause and lowermost stratosphere: insights into the transport pathways and total bromine

et al. 2021

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Abstract. We report on measurements of total bromine (Brtot) in the upper troposphere and lower stratosphere taken during 15 flights with the German High Altitude and LOng range research aircraft (HALO). The research campaign WISE (Wave-driven ISentropic Exchange) included regions over the North Atlantic, Norwegian Sea, and northwestern Europe in fall 2017. Brtot is calculated from measured total organic bromine (Brorg) added to inorganic bromine (Bryinorg), evaluated from measured BrO and photochemical modeling. Combining these data, the weighted mean [Brtot] is 19.2±1.2 ppt in the northern hemispheric lower stratosphere (LS), in agreement with expectations for Brtot in the middle stratosphere (Engel and Rigby et al., 2018). The data reflect the expected variability in Brtot in the LS due to variable influx of shorter lived brominated source and product gases from different regions of entry. A closer look into Brorg and Bryinorg, as well as simultaneously measured transport tracers (CO and N2O) and an air mass lag time tracer (SF6), suggests that bromine-rich air masses persistently protruded into the lowermost stratosphere (LMS) in boreal summer, creating a high bromine region (HBrR). A subsection, HBrR∗, has a weighted average of [Brtot] = 20.9±0.8 ppt. The most probable source region is air recently transported from the tropical upper troposphere and tropopause layer (UT/TTL) with a weighted mean of [Brtot] = 21.6±0.7 ppt. CLaMS Lagrangian transport modeling shows that the HBrR air mass consists of 51.2 % from the tropical troposphere, 27.1 % from the stratospheric background, and 6.4 % from the midlatitude troposphere (as well as contributions from other domains). The majority of the surface air reaching the HBrR is from the Asian monsoon and its adjacent tropical regions, which greatly influences trace gas transport into the LMS in boreal summer and fall. Tropical cyclones from Central America in addition to air associated with the Asian monsoon region contribute to the elevated Brtot observed in the UT/TTL. TOMCAT global 3-D model simulations of a concurrent increase of Brtot show an associated O3 change of -2.6±0.7 % in the LS and -3.1±0.7 % near the tropopause. Our study of varying Brtot in the LS also emphasizes the need for more extensive monitoring of stratospheric Brtot globally and seasonally to fully understand its impact on LMS O3 and its radiative forcing of climate, as well as in aged air in the middle stratosphere to elucidate the stratospheric trend in bromine.

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“…The 1992 Montreal Protocol concluded with the agreement to ban the production of CFCs in the world. However, banning the production of CFCs does not mean in any way that CFCs have disappeared from the atmosphere [3]. With data from the Earth System Research Laboratory/NOAA, it is observed that in the case of CFC-12, the current concentration is of the same order of magnitude as in 1990 (500 ppt); in the case of CFC-11, the current concentration is of the same order of magnitude as in 1985 (230 ppt); while the concentration of HCFC-22 went from 50 ppt in 1980 to 260 ppt in 2018 [4] [5].…”

Section: Introductionmentioning

confidence: 99%

Statistical Tests of the Validation of TCO Satellite Measurements, Recorded Simultaneously by TOMS-OMI (2005) and OMI-OMPS (2012-2018)

Molina-Almaraz¹,

Luis²,

Carlos³

et al. 2023

ACS

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Two statistical validation methods were used to evaluate the confidence level of the Total Column Ozone (TCO) measurements recorded by satellite systems measuring simultaneously, one using the normal distribution and another using the Mann-Whitney test. First, the reliability of the TCO measurements was studied hemispherically. While similar coincidences and levels of significance > 0.05 were found with the two statistical tests, an enormous variability in the levels of significance throughout the year was also exposed. Then, using the same statistical comparison methods, a latitudinal study was carried out in order to elucidate the geographical distribution that gave rise to this variability. Our study reveals that between the TOMS and OMI measurements in 2005 there was only a coincidence in 50% of the latitudes, which explained the variability. This implies that for 2005, the TOMS measurements are not completely reliable, except between the −50˚ and −15˚ latitude band in the southern hemisphere and between +15˚ and +50˚ latitude band in the northern hemisphere. In the case of OMI-OMPS, we observe that between 2011 and 2016 the measurements of both satellite systems are reasonably similar with a confidence level higher than 95%. However, in 2017 a band with a width of 20˚ latitude centered on the equator appeared, in which the significance levels were much less than 0.05, indicating that one of the measurement systems had begun to fail. In 2018, the fault was not only located in the equator, but was also replicated in various bands in the Southern Hemisphere. We interpret this as evidence of irreversible failure in one of the measurement systems.

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Aircraft‐Based Observations of Ozone‐Depleting Substances in the Upper Troposphere and Lower Stratosphere in and Above the Asian Summer Monsoon

Cited by 22 publications

References 84 publications

A Multimodel Investigation of Asian Summer Monsoon UTLS Transport Over the Western Pacific

A Multimodel Investigation of Asian Summer Monsoon UTLS Transport Over the Western Pacific

Organic and inorganic bromine measurements around the extratropical tropopause and lowermost stratosphere: insights into the transport pathways and total bromine

Statistical Tests of the Validation of TCO Satellite Measurements, Recorded Simultaneously by TOMS-OMI (2005) and OMI-OMPS (2012-2018)

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