Water vapor and cloud water measurements over Darwin during the STEP 1987 tropical mission

Kelly, K. K.; Proffitt, M. H.; Chan, K. R.; Loewenstein, M.; Podolske, J. R.; Strahan, S. E.; Wilson, John C.; Kley, D.

doi:10.1029/92jd02526

Cited by 98 publications

(67 citation statements)

References 23 publications

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“…There is a growing amount of observational evidence that overshooting convection, injecting material directly into the uppermost TTL has a moistening effect on the lower stratosphere (Kelly et al, 1993;Corti et al, 2008;de Reus et al, 2009;Schiller et al, 2009;Sargent et al, 2014). Consistent with the observations, simulations of overshooting events using cloudresolving modelling show significant localised moistening of the lower stratosphere (Chaboureau et al, 2007;Jensen et al, 2007;Grosvenor et al, 2007;Chemel et al, 2009;Liu et al, 2010).…”

Section: Introductionsupporting

confidence: 59%

Evidence of horizontal and vertical transport of water in the Southern Hemisphere tropical tropopause layer (TTL) from high-resolution balloon observations

et al. 2016

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Abstract. High-resolution in situ balloon measurements of water vapour, aerosol, methane and temperature in the upper tropical tropopause layer (TTL) and lower stratosphere are used to evaluate the processes affecting the stratospheric water budget: horizontal transport (in-mixing) and hydration by cross-tropopause overshooting updrafts. The obtained in situ evidence of these phenomena are analysed using satellite observations by Aura MLS (Microwave Limb Sounder) and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) together with trajectory and transport modelling performed using CLaMS (Chemical Lagrangian Model of the Stratosphere) and HYSPLIT (Hybrid SingleParticle Lagrangian Integrated Trajectory) model.Balloon soundings were conducted during March 2012 in Bauru, Brazil (22.3 • S) in the frame of the TRO-Pico campaign for studying the impact of convective overshooting on the stratospheric water budget. The balloon payloads included two stratospheric hygrometers: FLASH-B (Fluorescence Lyman-Alpha Stratospheric Hygrometer for Balloon) and Pico-SDLA instrument as well as COBALD (Compact Optical Backscatter Aerosol Detector) sondes, complemented by Vaisala RS92 radiosondes. Water vapour vertical profiles obtained independently by the two stratospheric hygrometers are in excellent agreement, ensuring credibility of the vertical structures observed.A signature of in-mixing is inferred from a series of vertical profiles, showing coincident enhancements in water vapour (of up to 0.5 ppmv) and aerosol at the 425 K (18.5 km) level. Trajectory analysis unambiguously links these features to intrusions from the Southern Hemisphere extratropical stratosphere, containing more water and aerosol, as demonstrated by MLS and CALIPSO global observations. The in-mixing is successfully reproduced by CLaMS simulations, showing a relatively moist filament extending to 20 • S. A signature of local cross-tropopause transport of water is observed in a particular sounding, performed on a convective day and revealing water vapour enhancements of up to 0.6 ppmv as high as the 404 K (17.8 km) level. These are shown to originate from convective overshoots upwind detected by an S-band weather radar operating locally in Bauru.Published by Copernicus Publications on behalf of the European Geosciences Union. S. M. Khaykin et al.: Evidence of horizontal and vertical transport of waterThe accurate in situ observations uncover two independent moisture pathways into the tropical lower stratosphere, which are hardly detectable by space-borne sounders. We argue that the moistening by horizontal transport is limited by the weak meridional gradients of water, whereas the fast convective cross-tropopause transport, largely missed by global models, can have a substantial effect, at least at a regional scale.

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Section: Introductionsupporting

confidence: 59%

Evidence of horizontal and vertical transport of water in the Southern Hemisphere tropical tropopause layer (TTL) from high-resolution balloon observations

et al. 2016

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“…Also in situ measurements performed over Hector within SCOUT-O3 provide evidence that this storm is hydrating, not dehydrating the TTL and the stratosphere to 2 km above the tropopause (Corti et al, 2008). Similar evidence for the presence of ice particles injected into the lowermost stratosphere by deep convective overshoots had been presented previously for the Hector system by Kelly et al (1993) and for other tropical thunderstorms over Brasil by Nielsen et al (2007).…”

Section: Introductionsupporting

confidence: 57%

The SCOUT-O3 Darwin Aircraft Campaign: rationale and meteorology

et al. 2009

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Abstract. An aircraft measurement campaign involving the Russian high-altitude aircraft M55 Geophysica and the German DLR Falcon was conducted in Darwin, Australia in November and December 2005 as part of the European integrated project SCOUT-O3. The overall objectives of the campaign were to study the transport of trace gases through the tropical tropopause layer (TTL), mechanisms of dehydration close to the tropopause, and the role of deep convection in these processes. In this paper a detailed roadmap of the campaign is presented, including rationales for each flight, and an analysis of the local and large-scale meteorological context in which they were embedded. The campaign took place during the pre-monsoon season which is characterized by a pronounced diurnal evolution of deep convection including a mesoscale system over the Tiwi Islands north of Darwin known as "Hector". This allowed studying in detail the role of deep convection in structuring the tropical tropopause region, in situ sampling convective overshoots above storm anvils, and probing the structure of anvils and cirrus clouds by Lidar and a suite of in situ instruments onboard the two aircraft. The large-scale flow during the first half of the campaign was such that local flights, away from convection, samCorrespondence to: D. Brunner (dominik.brunner@empa.ch) pled air masses downstream of the "cold trap" region over Indonesia. Abundant cirrus clouds enabled the study of active dehydration, in particular during two TTL survey flights. The campaign period also encompassed a Rossby wave breaking event transporting stratospheric air to the tropical middle troposphere and an equatorial Kelvin wave modulating tropopause temperatures and hence the conditions for dehydration.

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“…Though kept in the figure for illustration, the two AIRS data points at higher altitude are little significant being mostly representative of the a priori used in the retrieval. Below 17.5 km, HALOE is dry biased compared to all others, displaying a 2.3 ppmv minimum mixing ratio at about 16.4 km four times smaller than the saturation mixing ratio at −79 • C (the tropopause temperature) and therefore not attributable to local condensation, as reported at very cold (−85 • C) tropopause temperature such as over Northern Australia (Kelly et al, 1993). The SCIAMACHY profile is also dry biased compared to AIRS and µSDLA.…”

Section: Collocated Balloon In-situ and Satellites Remote Profilesmentioning

confidence: 60%

Evaluation of balloon and satellite water vapour measurements in the Southern tropical and subtropical UTLS during the HIBISCUS campaign

et al. 2009

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Abstract. Balloon water vapour in situ and remote measurements in the tropical upper troposphere and lower stratosphere (UTLS) obtained during the HIBISCUS campaign around 20 • S in Brazil in February-March 2004 using a tunable diode laser (µSDLA), a surface acoustic wave (SAW) and a Vis-NIR solar occultation spectrometer (SAOZ) on a long duration balloon, have been used for evaluating the performances of satellite borne remote water vapour instruments available at the same latitude and measurement period. In the stratosphere, HALOE displays the best precision (2.5%), followed by SAGE II (7%), MIPAS (10%), and SCIAMACHY (35%), all of which show approximately constant H 2 O mixing ratios between 20-25 km. Compared to HALOE of ±10% accuracy between 0.1-100 hPa, SAGE II and SAOZ show insignificant biases, MIPAS is wetter by 10% and SCIAMACHY dryer by 20%. The currently available GOMOS profiles of 25% precision show a positive vertical gradient in error for identified reasons. Compared to these, the water vapour of the Reprobus Chemistry Transport Model, forced at pressures higher than 95 hPa by the ECMWF analyses, is dryer by about 1 ppmv (20%).In the lower stratosphere between 16-20 km, most notable features are the steep degradation of MIPAS precision below 18 km, and the appearance of biases between instruments far larger than their quoted total uncertainty. HALOE and Correspondence to: N. Montoux (nadege.montoux@latmos.ipsl.fr) SAGE II (after spectral adjustment for reducing the bias with HALOE at northern mid-latitudes) both show decreases of water vapour with a minimum at the tropopause not seen by other instruments or the model, possibly attributable to an increasing error in the HALOE altitude registration. Between 16-18 km where the water vapour concentration shows little horizontal variability, and where the µSDLA balloon measurements are not perturbed by outgassing, the average mixing ratios reported by the remote sensing instruments are substantially lower than the 4-5 ppmv observed by the µSDLA. Differences between µSDLA and HALOE and SAGE II (of the order of −2 ppmv), SCIAMACHY, MIPAS and GOMOS (−1 ppmv) and SAOZ (−0.5 ppmv), exceed the 10% uncertainty of µSDLA, implying larger systematic errors than estimated for the various instruments.In the upper troposphere, where the water vapour concentration is highly variable, AIRS v5 appears to be the most consistent within its 25% uncertainty with balloon in-situ measurements as well as ECMWF. Most of the remote measurements show less reliability in the upper troposphere, losing sensitivity possibly because of absorption line saturation in their spectral ranges (HALOE, SAGE II and SCIA-MACHY), instrument noise exceeding 100% (MIPAS) or imperfect refraction correction (GOMOS). An exception is the SAOZ-balloon, employing smaller H 2 O absorption bands in the troposphere.

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Water vapor and cloud water measurements over Darwin during the STEP 1987 tropical mission

Cited by 98 publications

References 23 publications

Evidence of horizontal and vertical transport of water in the Southern Hemisphere tropical tropopause layer (TTL) from high-resolution balloon observations

Evidence of horizontal and vertical transport of water in the Southern Hemisphere tropical tropopause layer (TTL) from high-resolution balloon observations

The SCOUT-O3 Darwin Aircraft Campaign: rationale and meteorology

Evaluation of balloon and satellite water vapour measurements in the Southern tropical and subtropical UTLS during the HIBISCUS campaign

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