Some features of water vapor mixing ratio in tropical upper troposphere and lower stratosphere: Role of convection

2012 ◽  
Vol 108 ◽  
pp. 86-103 ◽  
Author(s):  
V. Panwar ◽  
A.R. Jain ◽  
A. Goel ◽  
T.K. Mandal ◽  
V.R. Rao ◽  
...  
Keyword(s):  
Water Vapor ◽  
Lower Stratosphere ◽  
Mixing Ratio ◽  
Upper Troposphere ◽  
Water Vapor Mixing Ratio ◽  
Tropical Upper Troposphere

scholarly journals Quantifying the Imprint of a Severe Hector Thunderstorm during ACTIVE/SCOUT-O3 onto the Water Content in the Upper Troposphere/Lower Stratosphere

2009 ◽  
Vol 137 (8) ◽  
pp. 2493-2514 ◽  
Author(s):  
Charles Chemel ◽  
Maria R. Russo ◽  
John A. Pyle ◽  
Ranjeet S. Sokhi ◽  
Cornelius Schiller
Keyword(s):  
Water Vapor ◽  
Water Content ◽  
Lower Stratosphere ◽  
Horizontal Resolution ◽  
Convective Transport ◽  
Mixing Ratio ◽  
Field Campaign ◽  
Upper Troposphere ◽  
Ice Particles ◽  
Water Vapor Mixing Ratio

Abstract The development of a severe Hector thunderstorm that formed over the Tiwi Islands, north of Australia, during the Aerosol and Chemical Transport in Tropical Convection/Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere (ACTIVE/SCOUT-O3) field campaign in late 2005, is simulated by the Advanced Research Weather Research and Forecasting (ARW) model and the Met Office Unified Model (UM). The general aim of this paper is to investigate the role of isolated deep convection over the tropics in regulating the water content in the upper troposphere/lower stratosphere (UT/LS). Using a horizontal resolution as fine as 1 km, the numerical simulations reproduce the timing, structure, and strength of Hector fairly well when compared with field campaign observations. The sensitivity of results from ARW to horizontal resolution is investigated by running the model in a large-eddy simulation mode with a horizontal resolution of 250 m. While refining the horizontal resolution to 250 m leads to a better representation of convection with respect to rainfall, the characteristics of the Hector thunderstorm are basically similar in space and time to those obtained in the 1-km-horizontal-resolution simulations. Several overshooting updrafts penetrating the tropopause are produced in the simulations during the mature stage of Hector. The penetration of rising towering cumulus clouds into the LS maintains the entrainment of air at the interface between the UT and the LS. Vertical exchanges resulting from this entrainment process have a significant impact on the redistribution of atmospheric constituents within the UT/LS region at the scale of the islands. In particular, a large amount of water is injected in the LS. The fate of the ice particles as Hector develops drives the water vapor mixing ratio to saturation by sublimation of the injected ice particles, moistening the air in the LS. The moistening was found to be fairly significant above 380 K and averaged about 0.06 ppmv in the range 380–420 K for ARW. As for UM, the moistening was found to be much larger (about 2.24 ppmv in the range of 380–420 K) than for ARW. This result confirms that convective transport can play an important role in regulating the water vapor mixing ratio in the LS.

scholarly journals First airborne water vapor lidar measurements in the tropical upper troposphere and mid-latitudes lower stratosphere: accuracy evaluation and intercomparisons with other instruments

2008 ◽  
Vol 8 (17) ◽  
pp. 5245-5261 ◽  
Author(s):  
C. Kiemle ◽  
M. Wirth ◽  
A. Fix ◽  
G. Ehret ◽  
U. Schumann ◽  
...  
Keyword(s):  
Water Vapor ◽  
Lower Stratosphere ◽  
Average Distance ◽  
Tropical Convection ◽  
Water Vapor Transport ◽  
Mixing Ratio ◽  
Upper Troposphere ◽  
Research Aircraft ◽  
Tropical Upper Troposphere

Abstract. In the tropics, deep convection is the major source of uncertainty in water vapor transport to the upper troposphere and into the stratosphere. Although accurate measurements in this region would be of first order importance to better understand the processes that govern stratospheric water vapor concentrations and trends in the context of a changing climate, they are sparse because of instrumental shortcomings and observational challenges. Therefore, the Falcon research aircraft of the Deutsches Zentrum für Luft- und Raumfahrt (DLR) flew a zenith-viewing water vapor differential absorption lidar (DIAL) during the Tropical Convection, Cirrus and Nitrogen Oxides Experiment (TROCCINOX) in 2004 and 2005 in Brazil. The measurements were performed alternatively on three water vapor absorption lines of different strength around 940 nm. These are the first aircraft DIAL measurements in the tropical upper troposphere and in the mid-latitudes lower stratosphere. Sensitivity analyses reveal an accuracy of 5% between altitudes of 8 and 16 km. This is confirmed by intercomparisons with the Fast In-situ Stratospheric Hygrometer (FISH) and the Fluorescent Advanced Stratospheric Hygrometer (FLASH) onboard the Russian M-55 Geophysica research aircraft during five coordinated flights. The average relative differences between FISH and DIAL amount to −3%±8% and between FLASH and DIAL to −8%±14%, negative meaning DIAL is more humid. The average distance between the probed air masses was 129 km. The DIAL is found to have no altitude- or latitude-dependent bias. A comparison with the balloon ascent of a laser absorption spectrometer gives an average difference of 0%±19% at a distance of 75 km. Six tropical DIAL under-flights of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board ENVISAT reveal a mean difference of −8%±49% at an average distance of 315 km. While the comparison with MIPAS is somewhat less significant due to poorer comparison conditions, the agreement with the in-situ hygrometers provides evidence of the excellent quality of FISH, FLASH and DIAL. Most DIAL profiles exhibit a smooth exponential decrease of water vapor mixing ratio in the tropical upper troposphere to lower stratosphere transition. The hygropause with a minimum mixing ratio of 2.5 µmol/mol is found between 15 and 17 km. A high-resolution (2 km horizontal, 0.2 km vertical) DIAL cross section through the anvil outflow of tropical convection shows that the ambient humidity is increased by a factor of three across 100 km.

scholarly journals Comparison of Fast In situ Stratospheric Hygrometer (FISH) measurements of water vapor in the upper troposphere and lower stratosphere (UTLS) with ECMWF (re)analysis data

2014 ◽  
Vol 14 (19) ◽  
pp. 10803-10822 ◽  
Author(s):  
A. Kunz ◽  
N. Spelten ◽  
P. Konopka ◽  
R. Müller ◽  
R. M. Forbes ◽  
...  
Keyword(s):  
Water Vapor ◽  
Lower Stratosphere ◽  
Analysis Data ◽  
Large Set ◽  
Mixing Ratio ◽  
Perfect Agreement ◽  
Upper Troposphere ◽  
Time Periods ◽  
Water Vapor Mixing Ratio

Abstract. An evaluation of water vapor in the upper troposphere and lower stratosphere (UTLS) of the ERA-Interim, the global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), is presented. Water vapor measurements are derived from the Fast In situ Stratospheric Hygrometer (FISH) during a large set of airborne measurement campaigns from 2001 to 2011 in the tropics, midlatitudes and polar regions, covering isentropic layers from 300 to 400K (5–18km). The comparison shows around 87% of the reanalysis data are within a factor of 2 of the FISH water vapor measurements and around 30% have a nearly perfect agreement with an over- and underestimation lower than 10%. Nevertheless, strong over- and underestimations can occur both in the UT and LS, in particularly in the extratropical LS and in the tropical UT, where severe over- and underestimations up to 10 times can occur. The analysis data from the evolving ECMWF operational system is also evaluated, and the FISH measurements are divided into time periods representing different cycles of the Integrated Forecast System (IFS). The agreement with FISH improves over the time, in particular when comparing water vapor fields for time periods before 2004 and after 2010. It appears that influences of tropical tropospheric and extratropical UTLS processes, e.g., convective and quasi-isentropic exchange processes, are particularly challenging for the simulation of the UTLS water vapor distribution. Both the reanalysis and operational analysis data show the tendency of an overestimation of low water vapor mixing ratio (⪅10ppmv) in the LS and underestimation of high water vapor mixing ratio (⪆300ppmv) in the UT.

scholarly journals First airborne water vapor lidar measurements in the tropical upper troposphere and mid-latitudes lower stratosphere: accuracy evaluation and intercomparisons with other instruments

2008 ◽  
Vol 8 (3) ◽  
pp. 10353-10396 ◽  
Author(s):  
C. Kiemle ◽  
M. Wirth ◽  
A. Fix ◽  
G. Ehret ◽  
U. Schumann ◽  
...  
Keyword(s):  
Water Vapor ◽  
Lower Stratosphere ◽  
Average Distance ◽  
Tropical Convection ◽  
Water Vapor Transport ◽  
Mixing Ratio ◽  
Upper Troposphere ◽  
Research Aircraft ◽  
Tropical Upper Troposphere

Abstract. In the tropics, deep convection is the major source of uncertainty in water vapor transport to the upper troposphere and into the stratosphere. Although accurate measurements in this region would be of first order importance to better understand the processes that govern stratospheric water vapor concentrations and trends in the context of a changing climate, they are sparse because of instrumental shortcomings and observational challenges. Therefore, the Falcon research aircraft of the Deutsches Zentrum für Luft- und Raumfahrt (DLR) flew a zenith-viewing water vapor differential absorption lidar (DIAL) during the Tropical Convection, Cirrus and Nitrogen Oxides Experiment (TROCCINOX) in 2004 and 2005 in Brazil. The measurements were performed alternatively on three water vapor absorption lines of different strength around 940 nm. These are the first aircraft DIAL measurements in the tropical upper troposphere and in the mid-latitudes lower stratosphere. A sensitivity analysis reveals that the DIAL profiles have an accuracy of ~5% between altitudes of 8 and 16 km. This is confirmed by intercomparisons with the Fast In-situ Stratospheric Hygrometer (FISH) and the Fluorescent Advanced Stratospheric Hygrometer (FLASH) onboard the Russian M-55 Geophysica research aircraft during five coordinated flights. The average relative differences between FISH and DIAL amount to –3%±8% and between FLASH and DIAL to –8%±14%, negative meaning DIAL is more humid. The average distance between the probed air masses was 129 km. The DIAL is found to have no altitude- or latitude-dependent bias. A comparison with the balloon ascent of a laser absorption spectrometer gives an average difference of 0%±19% at a distance of 75 km. Six tropical DIAL under-flights of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board ENVISAT show a mean difference of –8%±49% at an average distance of 315 km. While the comparison with MIPAS is somewhat less significant due to poorer comparison conditions, the agreement with the in-situ hygrometers provides evidence of the excellent quality of FISH, FLASH and DIAL. Most DIAL profiles exhibit a smooth exponential decrease of water vapor mixing ratio in the tropical upper troposphere to lower stratosphere transition. The hygropause with a minimum mixing ratio of ~2.5 μmol/mol is found between 15 and 16 km, 1 to 2 km beneath the local tropopause. A high-resolution (2 km horizontal, ~200 m vertical) DIAL cross section through the anvil outflow of tropical convection shows that the ambient humidity is increased by a factor of three across 100 km.

Direct injection of water vapor into the lower stratosphere through extreme convection: A case study for the summer 2019 in the mid latitudes

2020 ◽  
Author(s):  
Dina Khordakova ◽  
Christian Rolf ◽  
Martina Krämer ◽  
Martin Riese
Keyword(s):  
Water Vapor ◽  
Satellite Images ◽  
Lower Stratosphere ◽  
Global Climate ◽  
Direct Injection ◽  
Reanalysis Data ◽  
Radiation Budget ◽  
Mixing Ratio ◽  
Mixing Ratios ◽  
Water Vapor Mixing Ratio

<p>Water vapor is one of the strongest greenhouse gases of the atmosphere. Its driving role in the upper troposphere / lower stratosphere region (UTLS) for the radiation budget was shown by e.g. Riese et al., (2012). Despite its low abundance of 4 - 6 ppmv in the stratosphere, even small changes in its mixing ratio can leed to a positive feedback to global warming. To better understand changes and variability of water vapor in the lower stratosphere, we focus here on exchange processes from the moist troposphere to the dry stratosphere in the mid latitudes. These processes are caused by extreme vertical convection, which is expected to increase in intensity and frequency with progressive global climate change.</p><p>Within the MOSES (Modular Observation Solutions for Earth Systems) campaign in the summer of 2019, two extreme vertical convection events could be captured with balloon borne humidity sensors over the eastern part of Germany. The comparison of measurements before and after both events reveal distinct water vapor enhancements in the lower stratosphere and show that even in mid-latitudes over shooting convection can impact the water vapor mixing ratio in the UTLS. The measurements are compared with the Microwave Limb Sounder (MLS) data as well as ECMWF reanalysis data.</p><p><span>We will show a deeper analysis of both events by using visible and infrared weather satellite images in combination with meteorological fields of ECMWF. </span><span>B</span><span>ackward trajectories of the air masses </span><span>with the enriched water vapor mixing ratios </span><span>calculated with</span><span> the CLAMS model </span><span>and</span> <span>combined</span><span> with the satellite images can </span><span>confirm the convective origin. </span><span>Additionally,</span><span> we show the </span><span>further </span><span>development of this distinct water vapor filaments within the lower stratosphere </span><span>in order to</span><span> trace the transport and mixing process, </span><span>based on an</span> <span>analysis of forward trajectories.</span></p>

scholarly journals Interannual variations of water vapor in the tropical upper troposphere and the lower and middle stratosphere and their connections to ENSO and QBO

2018 ◽  
Author(s):  
Edward W. Tian ◽  
Hui Su ◽  
Baijun Tian ◽  
Jonathan H. Jiang
Keyword(s):  
Water Vapor ◽  
Lower Stratosphere ◽  
Phase Lag ◽  
Interannual Variations ◽  
Quasi Biennial Oscillation ◽  
Upper Troposphere ◽  
Tropical Water ◽  
Enso Phases ◽  
Middle Stratosphere ◽  
Tropical Upper Troposphere

Abstract. In this study, we analyze the Aura Microwave Limb Sounder water vapor data in the tropical upper troposphere and the lower and middle stratosphere (UTLMS) (from 215 hPa to 6 hPa) for the period from August 2004 to September 2017 using time-lag regression analysis and composite analysis to explore the interannual variations of tropical UTLMS water vapor and their connections to El Nino Southern Oscillation (ENSO) and quasi-biennial oscillation (QBO). Our analysis shows that ENSO’s impact on the interannual tropical water vapor anomalies is strong in the upper troposphere (~215 to ~120 hPa) and near the tropopause (~110 to ~90 hPa) with a ~3-month lag but weak in the lower and middle stratosphere (~80 to ~6 hPa). In contrast, QBO has a large impact on the interannual tropical water vapor anomalies in the lower and middle stratosphere with an upward propagating signal starting at the tropopause (100 hPa), peaking first in the lower stratosphere near 68 hPa with a ~7-month lag and then in the middle stratosphere near 15 hPa with a ~24-month lag. The phase lag is based on the 30-hPa QBO index and should be different from that found by previous studies based on the 50-hPa QBO index. In the upper troposphere, interannual tropical water vapor anomalies are positive during the warm ENSO phases but negative during the cold ENSO phases no matter what QBO phases are. Near the tropopause, interannual tropical water vapor anomalies are different depending on different ENSO and QBO phase combinations. In the lower and middle stratosphere, interannual tropical water vapor anomalies are mainly determined by QBO instead of ENSO. For the easterly QBO phases, interannual tropical water vapor anomalies are positive in the lower stratosphere but negative in the middle stratosphere. Vice versa for the westerly QBO phases.

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