Balloon-borne measurements of temperature, water vapor, ozone and aerosol backscatter at the southern slopes of the Himalayas during StratoClim 2016-2017

Brunamonti, Simone; Jorge, Teresa; Oelsner, Peter; Hanumanthu, Sreeharsha; Singh, Bhupendra Bahadur; Kumar, K. Ravi; Sonbawne, S. M.; Meier, S.; Singh, Deepak; Wienhold, F. G.; Luo, B. P.; Boettcher, Maxi; Poltera, Yann; Jauhiainen, Hannu; Kayastha, Rijan Bhakta; Dirksen, Ruud; Naja, Manish; Rex, Markus; Peter, Thomas

doi:10.5194/acp-2018-222

Cited by 18 publications

(56 citation statements)

References 5 publications

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“…These were campaign mean results, whereas flight by flight discrepancies as large as 50% could occur. In previous publications of this dataset (Brunamonti et al, 2018(Brunamonti et al, , 2019, contaminated measurements in the stratosphere were discarded using an empirical threshold. In particular, all data above the cold-point tropopause (CPT) was flagged as contaminated, if H 2 O mixing ratios exceeded 10 ppmv at any altitude in the stratosphere.…”

Section: Cfh and Rs41 Water Vapour Measurementsmentioning

confidence: 99%

“…Over time this type of contamination has been reduced by increasing the length of the cord by means of an unwinder and by giving preference to descent over ascent data (Mastenbrook and Dinger, 1961;Mastenbrook, 1965Mastenbrook, , 1968Mastenbrook and Oltmans, 1983;Oltmans and Hofmann, 1995;Vömel et al, 1995;Oltmans et al, 2000;Khaykin et al, 2013;Hall et al, 2016). Standard lengths presently used are of the order of 50 to 60 m (Vömel et al, 2016;Brunamonti et al, 2018). The World Meteorological Organization recommends ropes longer than 40 m (WMO, 2008;Immler et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…With the increasing miniaturization and ease of use, balloon-borne frost point hygrometers started to be employed more systematically at an increasing number of locations and under a wide range of meteorological conditions (Vömel et al, 2002(Vömel et al, , 2007bBian et al, 2012;Hall et al, 2016;Brunamonti et al, 2018), creating new challenges for the instrument. When passing through mixed-phase clouds with supercooled liquid droplets, the balloon and payload surfaces can accumulate ice, which will sublimate in the subsaturated environment of the stratosphere.…”

Section: Introductionmentioning

confidence: 99%

“…2 StratoClim Balloon Campaigns Brunamonti et al (2018) offers an overview of the instrumentation and dataset collected during the 2016 -2017 StratoClim balloon campaigns at the southern slopes of the Himalayas, deriving a comprehensive understanding of the morphology and https://doi.org/10.5194/amt-2020-176 Preprint. Discussion started: 29 May 2020 c Author(s) 2020.…”

Section: Introductionmentioning

confidence: 99%

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Understanding cryogenic frost point hygrometer measurements after contamination by mixed-phase clouds

Jorge¹,

Brunamonti²,

Poltera³

et al. 2020

Preprint

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Abstract. Balloon-borne water vapour measurements in the (sub)tropical upper troposphere and lower stratosphere (UTLS) by means of frost point hygrometers provide important information on air chemistry and climate. However, the risk of contamination from sublimating hydrometeors collected by the intake tube may render these measurements difficult, particularly after crossing low clouds containing supercooled droplets. A large set of measurements during the 2016–2017 StratoClim balloon campaigns at the southern slopes of the Himalayas allows us to perform an in-depth analysis of this type of contamination. We investigate the efficiency of wall-contact and freezing of supercooled droplets in the intake tube and the subsequent sublimation in the UTLS using Computational Fluid Dynamics (CFD). We find that the airflow can enter the intake tube with impingement angles up to 60°, owing to the pendulum motion of the payload. Supercooled droplets with radii > 70 μm, as they frequently occur in mid-tropospheric clouds, typically undergo contact freezing when entering the intake tube, whereas only about 50 % of droplets with 10 μm radius freeze, and droplets 100 ppmv) in the stratosphere. Furthermore, we use CFD to differentiate between stratospheric water vapour contamination by an icy intake tube and contamination caused by outgassing from the balloon and payload, revealing that the latter starts playing a role only at high altitudes (p

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Section: Cfh and Rs41 Water Vapour Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Understanding cryogenic frost point hygrometer measurements after contamination by mixed-phase clouds

Jorge¹,

Brunamonti²,

Poltera³

et al. 2020

Preprint

Self Cite

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“…where BSRblue and BSRred are backscatter ratios at wavelengths of 455 nm and 940 nm, respectively. CI is used to separate in-cloud (CI>7) from clear sky (CI<7) (Vernier et al, 2015;Brunamonti et al, 2018).…”

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confidence: 99%

High tropospheric ozone in Lhasa within the Asian summer monsoon anticyclone 2013: influence of convective transport and stratospheric intrusions

Li¹,

Vogel²,

Müller³

et al. 2018

Preprint

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<p><strong>Abstract.</strong> Balloon-borne measurements of ozone in Lhasa (29.66&#176;&#8201;N, 91.14&#176;&#8201;E, 3650&#8201;m above sea level) in August 2013 are investigated using backward trajectory calculations performed with the Chemical Lagrangian Model of the Stratosphere (CLaMS). Measurements show three time periods characterized by high ozone mixing ratios in the troposphere on 8, 11, and 18&#8211;20 August 2013 during the Asian summer monsoon season. Here, we could verify two different sources for the enhanced ozone values in the troposphere. First, transport of polluted air from the boundary layer, and second transport from the stratosphere by stratospheric intrusions. Air pollution from South Asia through convective and long-range transport plays a key role in enhancing middle/upper tropospheric ozone mixing ratios up to 90&#8201;% on 8 August and up to 125&#8201;% on 11 August 2013. Stratospheric air intruded from the northern high-latitude to the southeastern flank of the Asian summer monsoon (ASM) anticyclone to the troposphere and is identified as source of enhanced ozone according to backward trajectory calculation and satellite measurements by the Ozone Monitoring Instrument (OMI) and the Atmospheric Infrared Sounder (AIRS). Air parcels with high ozone moved from the high latitude lower stratosphere to the middle/upper troposphere and are then transported to Lhasa over a long-distance and enhanced upper middle/tropospheric ozone in Lhasa during 18&#8211;20 August 2013. Our findings demonstrate that the strong variability of ozone within the ASM anticyclone in the free troposphere is caused by transport from different regions of the atmosphere.</p>

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How reliable are Coupled Model Intercomparison Project Phase 6 models in representing the Asian summer monsoon anticyclone?

Singh

Kumar

Seelanki

et al. 2022

Intl Journal of Climatology

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We assess the Asian summer monsoon anticyclone (ASMA) in Coupled Model Intercomparison Project Phase 6 (CMIP6) models for the historical period . The ASMA is a quasi-stationary warm anticyclone during the boreal summer monsoon season, centred around Tibet. It is a prominent circulation feature that affects trace species transport, stratosphere-troposphere exchange, along with strong feedbacks to weather and climate. The study is a novel attempt to quantify the performance of models participating in the CMIP6 consortium and understand long-term variability and teleconnections of the ASMA. We note that CMIP6 models capture the mean ASMA features reasonably well, albeit with some differences around the edges. For most of the models, interannual variations are not in phase with the reanalysis and show sharper increasing trend in the ASMA strength. There is about a twofold increase in the trends during the recent period as compared to the 1950-2014 period. A multimodel mean (MME) chosen based upon the statistical metrics (mean, standard deviation, mean absolute error and root-meansquare error), target diagram, and density distributions is further used to examine the prominent modes of variability. Our results suggest that the signals of significant periodicity, particularly the 2-4 years signal, and the SST correlations in MME are inconsistent with observations. In CMIP6 models, we note stronger upper level divergence over the western and eastern Pacific but convergence over the Indian ocean, South Asia and the central Pacific. The streamfunction and rotational winds also show strong highs north of 20 N.Overall, it is seen that basic features such as spatial extent and evolution of ASMA are reasonably captured, but the strength and interannual variations are dissonant across the CMIP6 models. These findings are useful for studies focusing on regional meteorology, transportation of atmospheric tracers and climate change projections over the region involving the ASMA.

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Balloon-borne measurements of temperature, water vapor, ozone and aerosol backscatter at the southern slopes of the Himalayas during StratoClim 2016-2017

Cited by 18 publications

References 5 publications

Understanding cryogenic frost point hygrometer measurements after contamination by mixed-phase clouds

Understanding cryogenic frost point hygrometer measurements after contamination by mixed-phase clouds

High tropospheric ozone in Lhasa within the Asian summer monsoon anticyclone 2013: influence of convective transport and stratospheric intrusions

How reliable are Coupled Model Intercomparison Project Phase 6 models in representing the Asian summer monsoon anticyclone?

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