Impact of tropical land convection on the water vapour budget in the tropical tropopause layer

Carminati, Fabien; Ricaud, Philippe; Pommereau, Jean‐Pierre; Rivière, Emmanuel; Khaykin, Sergey; Attié, J.-L.; Warner, J. X.

doi:10.5194/acp-14-6195-2014

Cited by 17 publications

(32 citation statements)

References 68 publications

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“…Also diurnal effects (e.g. Carminati et al, 2014) can play a role if there is a systematic time difference between the data sets (e.g. Damadeo et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

UTLS water vapour from SCIAMACHY limb measurementsV3.01 (2002–2012)

et al. 2016

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Abstract. The SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) aboard the Envisat satellite provided measurements from August 2002 until April 2012. SCIAMACHY measured the scattered or direct sunlight using different observation geometries. The limb viewing geometry allows the retrieval of water vapour at about 10-25 km height from the near-infrared spectral range (1353-1410 nm). These data cover the upper troposphere and lower stratosphere (UTLS), a region in the atmosphere which is of special interest for a variety of dynamical and chemical processes as well as for the radiative forcing. Here, the latest data version of water vapour (V3.01) from SCIAMACHY limb measurements is presented and validated by comparisons with data sets from other satellite and in situ measurements. Considering retrieval tests and the results of these comparisons, the V3.01 data are reliable from about 11 to 23 km and the best results are found in the middle of the profiles between about 14 and 20 km. Above 20 km in the extra tropics V3.01 is drier than all other data sets. Additionally, for altitudes above about 19 km, the vertical resolution of the retrieved profile is not sufficient to resolve signals with a short vertical structure like the tape recorder. Below 14 km, SCIAMACHY water vapour V3.01 is wetter than most collocated data sets, but the high variability of water vapour in the troposphere complicates the comparison. For 14-20 km height, the expected errors from the retrieval and simulations and the mean differences to collocated data sets are usually smaller than 10 % when the resolution of the SCIAMACHY data is taken into account. In general, the temporal changes agree well with collocated data sets except for the Northern Hemisphere extratropical stratosphere, where larger differences are observed. This indicates a possible drift in V3.01 most probably caused by the incomplete treatment of volcanic aerosols in the retrieval. In all other regions a good temporal stability is shown. In the tropical stratosphere an increase in water vapour is found between 2002 and 2012, which is in agreement with other satellite data sets for overlapping time periods.Published by Copernicus Publications on behalf of the European Geosciences Union.

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“…Also diurnal effects (e.g. Carminati et al, 2014) can play a role if there is a systematic time difference between the data sets (e.g. Damadeo et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

UTLS water vapour from SCIAMACHY limb measurementsV3.01 (2002–2012)

et al. 2016

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“…Regional effects of overshooting have been detected in various tropospheric tracers, such as N 2 O, CH 4 and CO (Ricaud et al, 2007(Ricaud et al, , 2009 . Carminati et al (2014) used MLS daytime and night-time observations to investigate the diurnal cycle of water vapour, cloud ice-water and temperature.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…In contrast to that, Randel et al (2015) found that enhanced tropospheric convection within Asian and North American monsoons leads to reduced stratospheric water vapour. While upscaling the overshooting events and quantifying their net effect on water vapour remains a difficult task, various space-borne observations suggest that the most vigorous convection, capable of direct transport of material into the lower stratosphere, is mostly restricted to the tropical land regions (Liu and Zipser, 2005;Ricaud et al, 2009;Iwasaki et al, 2010;Bergman et al, 2012;Khaykin et al, 2013a;Carminati et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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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“…Although seasonal and annual variations of H 2 O have been extensively studied, few studies were devoted to the geographical and temporal variability of its diurnal cycle in the TTL. In Carminati et al (2014), the impact of the continental tropical convection on the H 2 O variability was debated by considering the 8-year Microwave Limb Sounder (MLS) H 2 O, cloud ice water content and temperature data sets from 2005 to 2014. The interplays between these parameters and their role in the water vapour variability in the TTL were highlighted separately in the northern and southern tropics.…”

Section: Introductionmentioning

confidence: 99%

“…The interplays between these parameters and their role in the water vapour variability in the TTL were highlighted separately in the northern and southern tropics. The analysis from Carminati et al (2014) adopted the Liu and Zipser (2009) philosophy to discuss the difference between daytime and night-time data sets, with the aim of better apprehending the role of continental convection in hydrating and dehydrating processes in the TTL.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of water vapour assimilation in the tropical upper troposphere and lower stratosphere by a chemical transport model

Payra

Ricaud²,

Abida³

et al. 2016

Atmos. Meas. Tech.

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Abstract. The present analysis deals with one of the most debated aspects of the studies on the upper troposphere/lower stratosphere (UTLS), namely the budget of water vapour (H 2 O) at the tropical tropopause. Within the French project "Multiscale water budget in the upper troposphere and lower stratosphere in the TROpics" (TRO-pico), a global-scale analysis has been set up based on space-borne observations, models and assimilation techniques. The MOCAGE-VALENTINA assimilation tool has been used to assimilate the Aura Microwave Limb Sounder (MLS) version 3.3 H 2 O measurements within the 316-5 hPa range from August 2011 to March 2013 with an assimilation window of 1 h. Diagnostics based on observations minus analysis and forecast are developed to assess the quality of the assimilated H 2 O fields. Comparison with an independent source of H 2 O measurements in the UTLS based on the space-borne Michelson Interferometer for Passive Atmospheric Sounding (MI-PAS) observations and with meteorological ARPEGE analyses is also shown. Sensitivity studies of the analysed fields have been performed by (1) considering periods when no MLS measurements are available and (2) using H 2 O data from another MLS version (4.2). The studies have been performed within three different spaces in time and space coincidences with MLS (hereafter referred to as MLS space) and MIPAS (MIPAS space) observations and with the model (model space) outputs and at three different levels: 121 hPa (upper troposphere), 100 hPa (tropopause) and 68 hPa (lower stratosphere) in January and February 2012. In the MLS space, the analyses behave consistently with the MLS observations from the upper troposphere to the lower stratosphere. In the model space, the analyses are wetter than the reference atmosphere as represented by ARPEGE and MLS in the upper troposphere (121 hPa) and around the tropopause (100 hPa), but are consistent with MLS and MIPAS in the lower stratosphere (68 hPa). In the MIPAS space, the sensitivity and the vertical resolution of the MIPAS data set at 121 and 100 hPa prevent assessment of the behaviour of the analyses at 121 and 100 hPa, particularly over intense convective areas as the South American, the African and the Maritime continents but, in the lower stratosphere (68 hPa), the analyses are very consistent with MIPAS. Sensitivity studies show the improvement on the H 2 O analyses in the tropical UTLS when assimilating space-borne measurements of better quality, particularly over the convective areas.

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Impact of tropical land convection on the water vapour budget in the tropical tropopause layer

Cited by 17 publications

References 68 publications

UTLS water vapour from SCIAMACHY limb measurementsV3.01 (2002–2012)

UTLS water vapour from SCIAMACHY limb measurementsV3.01 (2002–2012)

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

Evaluation of water vapour assimilation in the tropical upper troposphere and lower stratosphere by a chemical transport model

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