scholarly journals Lower atmosphere water/hydrogen activity during the MY 34 regional dust storm

2020 ◽  
Author(s):  
James A. Holmes ◽  
Stephen R. Lewis ◽  
Manish R. Patel ◽  
Shohei Aoki ◽  
Anna A. Fedorova ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Water Vapour ◽  
Dust Storm ◽  
Circulation Model ◽  
Global Distribution ◽  
Lower Atmosphere ◽  
Dynamical Structure ◽  
Time Period ◽  
Spacecraft Data ◽  
Water Hydrogen

<div> <p>Our understanding of the evolution of water on Mars can be advanced through the provision of bounded constraints on the rates of water loss. To understand observed variations in the loss rate, the processes via which hydrogen escapes the martian atmosphere and coupling to the lower atmosphere water cycle also need to be explored. During the Mars Year (MY) 34 regional dust storm that occurred from <em>L</em><sub>S</sub> = 320.6-336.5°, an increase in the Lyman alpha brightness (a proxy for hydrogen escape) was observed by the Mars Atmosphere and Volatile EvolutioN Imaging Ultraviolet Spectrograph (MAVEN/IUVS) instrument.  Vertical profiles of water vapour can be retrieved from the Nadir and Occultation for MArs Discovery (NOMAD) and Atmospheric Chemistry Suite (ACS) instruments on the ExoMars Trace Gas Orbiter (TGO). Retrievals could not be made, however, at the time of peak activity observed by MAVEN/IUVS, during the MY 34 regional dust storm. </p> </div> <div> <p>We investigate the global distribution of lower atmosphere water using data assimilation covering the time period leading up to and during the MY 34 regional dust storm. The data includes observations of water vapour from NOMAD/ACS (that constrain the initial global distribution of water), temperature profiles from ACS and the Mars Climate Sounder (MCS) on the Mars Reconnaissance Orbiter spacecraft, and dust column from MCS, which are combined with the Open University modelling group Mars Global Circulation model. During the time period of the MY 34 regional dust storm unobserved by ExoMars TGO we can still constrain the simulation using MCS temperature and dust column retrievals, a powerful advantage of multi-spacecraft data assimilation. This method provides the most realistic simulation possible of the chemical and dynamical structure of the lower atmosphere during the observed peak in MAVEN/IUVS observations.  </p> </div> <div> <p>We identify peak abundance of water vapour and hydrogen at altitudes above 70 km that are consistent with the peak emission observed by MAVEN/IUVS. Spatial variations in elevated water/hydrogen across the globe are linked to the underlying circulation patterns during the MY 34 regional dust storm. </p> </div><!-- COMO-HTML-CONTENT-END --> <!-- COMO-HTML-CONTENT-END --> <p class="co_mto_htmlabstract-citationHeader"> <strong class="co_mto_htmlabstract-citationHeader-intro">How to cite:</strong> Holmes, J. A., Lewis, S. R., Patel, M. R., Aoki, S., Fedorova, A. A., Chaffin, M. S., Schneider, N. M., Kass, D. M., and Vandaele, A. C.: Lower atmosphere water/hydrogen activity during the MY 34 regional dust storm , Europlanet Science Congress 2020, online, 21 September–9 Oct 2020, EPSC2020-772, 2020 </p>

Global variations in the vertical distribution of water during Mars Year 34 from multiple spacecraft observations

2021 ◽  
Author(s):  
James Holmes ◽  
Stephen Lewis ◽  
Manish Patel ◽  
Shohei Aoki ◽  
Giuliano Liuzzi ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Vertical Distribution ◽  
Water Vapour ◽  
Hydrological Cycle ◽  
Circulation Model ◽  
Transport Processes ◽  
Temperature Profiles ◽  
Saturation State ◽  
Spacecraft Data ◽  
The Vertical Distribution

<div> <p><span data-contrast="auto">Observations of the vertical distribution of water vapour provide a unique snapshot of the vertical transport processes that contribute to the global martian hydrological cycle. While previous datasets have largely been seasonally and spatially sparse, vertical profiles of water retrieved from the Nadir and Occultation for MArs Discovery (NOMAD) and Atmospheric Chemistry Suite (ACS) instruments on the ExoMars Trace Gas Orbiter (TGO) provide the most complete dataset so far. These data are now capable of providing robust constraints on the 4-D distribution of water, especially when also combined with retrievals of additional atmospheric properties (e.g. temperature profiles, dust column) that exert an influence on the evolving global water distribution. </span><span data-ccp-props="{"335551550":6,"335551620":6}"> </span></p> </div> <div> <p><span data-contrast="auto">A key limitation though is the fact that observations of water profiles are still relatively limited in coverage, in the global sense, and the vertical distribution of water at latitudes and times not regularly probed by NOMAD and ACS remains poorly understood.  </span><span data-ccp-props="{"335551550":6,"335551620":6}"> </span></p> </div> <div> <p><span data-contrast="auto">To address this, we have created a global reference climatology of water vertical distribution for Mars Year (MY) 34 through a multi-spacecraft data assimilation combining several retrieval datasets with a Mars Global Circulation Model. Retrievals of dust column and temperature profiles from Mars Climate Sounder on the Mars Reconnaissance Orbiter and water vapour and temperature profiles from multiple instruments on the ExoMars TGO during the primary science phase covering the latter half of MY34 are combined through assimilation to create one unified physically consistent global dataset.</span><span data-ccp-props="{"335551550":6,"335551620":6}"> </span></p> </div> <div> <p><span data-contrast="auto">The vertical water vapour distribution is investigated globally. During the initial coverage of TGO observation that covers the dusty season in MY34, northern polar latitudes are largely absent of water vapour below 20 km with variations in abundance above this altitude throughout the dusty season linked to transport from mid-latitudes during a global dust storm, perihelion season and the intense MY34 C storm. The atmosphere is in a supersaturated state above 60 km for most of the time period investigated, with lower altitudes showing more diurnal variation in the saturation state of the atmosphere. A key benefit of the data assimilation technique is that constraints on dynamical transport imposed by the assimilated water vapour and temperature profiles leads to improvements in the simulated water ice distribution even though it is not altered directly by the assimilation process.</span><span data-ccp-props="{"335551550":6,"335551620":6}"> </span></p> </div> <div> <p><span data-contrast="auto">The climatology created, which will become publicly available for wider use by the martian scientific community, has also been independently validated against water vapour profiles from the SPICAM instrument.</span><span data-ccp-props="{"335551550":6,"335551620":6}"> </span></p> </div>

scholarly journals Explanation for the increase in high altitude water on Mars observed by NOMAD during the 2018 global dust storm

2020 ◽  
Author(s):  
Lori Neary ◽  
Frank Daerden ◽  
Shohei Aoki ◽  
James Whiteway ◽  
Robert Todd Clancy ◽  
...  
Keyword(s):  
High Altitude ◽  
Water Vapour ◽  
Dust Storm ◽  
General Circulation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Atmospheric Escape ◽  
Mars Model ◽  
The Tropics ◽  
The Vertical Distribution

<p>Using the GEM-Mars three-dimensional general circulation model (GCM), we examine the mechanism responsible for the enhancement of water vapour in the upper atmosphere as measured by the Nadir and Occultation for MArs Discovery (NOMAD) instrument onboard ExoMars Trace Gas Orbiter (TGO) during the 2018 global dust storm on Mars.</p><p>Experiments with different prescribed vertical profiles of dust show that when more dust is present higher in the atmosphere, the temperature increases and the amount of water ascending over the tropics is not limited by saturation until reaching heights of 70-100 km. The warmer temperatures allow more water to ascend to the mesosphere. The simulation of enhanced high-altitude water abundances is very sensitive to the vertical distribution of the dust prescribed in the model.</p><p>The GEM-Mars model includes gas-phase photochemistry, and these simulations show how the increased water vapour over the 40-100 km altitude range results in the production of high-altitude atomic hydrogen which can be linked to atmospheric escape.</p>

Enhanced Super-rotation before and during the MY34 Martian Global Dust Storm

2021 ◽  
Author(s):  
Kylash Rajendran ◽  
Stephen R. Lewis ◽  
James A. Holmes ◽  
Paul M. Streeter ◽  
Anna A. Fedorova ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Atmospheric Chemistry ◽  
Dust Storm ◽  
Rapid Development ◽  
Hadley Cell ◽  
Lower Atmosphere ◽  
Westerly Jet ◽  
Dust Distribution ◽  
The Tropics ◽  
Thermal Tides

<p class="paragraph">The presence of an equatorial westerly jet in a planetary atmosphere is often referred to as super-rotation. On Mars, super-rotation affects – and is affected by – the distribution of dust in the atmosphere. We used data assimilation to study the interaction between dust and the equatorial jet during the MY34 Mars global dust storm (GDS). The data assimilation scheme integrated temperature and dust retrievals from the Mars Climate Sounder aboard the Mars Reconnaissance Orbiter and the Atmospheric Chemistry Suite aboard the ExoMars Trace Gas Orbiter into a numerical model of the Martian atmosphere. This created a better representation of the atmospheric state than could be achieved from the observations or the model alone.</p> <p class="paragraph">We found that super-rotation increased by a factor of two at the peak of the GDS, as compared to the same period in the previous year which did not feature a GDS. A strong westerly jet formed in the tropical lower atmosphere, and easterlies were strengthened above 60 km, as a result of momentum transport by dust-driven thermal tides. We found that the atmosphere was in a state of enhanced super-rotation even before the onset of the GDS, as a result of equatorward advection of dust from the southern mid-latitudes into the tropics. The redistribution of dust across the hemispheres resulted in a more uniform dust distribution across the tropics, leading to a symmetric Hadley cell with a tropical upwelling branch that was closely aligned to the vertical. We argue that the symmetrical circulation and enhanced super-rotation were important environmental factors that encouraged the rapid development of the MY34 GDS.</p>

scholarly journals Enhanced water loss during the Mars Year 34 C storm

2021 ◽  
Author(s):  
James Holmes ◽  
Stephen Lewis ◽  
Manish Patel ◽  
Michael Chaffin ◽  
Eryn Cangi ◽  
...  
Keyword(s):  
Water Vapour ◽  
Atmospheric Chemistry ◽  
Water Loss ◽  
Circulation Model ◽  
Dust Storms ◽  
Lower Atmosphere ◽  
Late Winter ◽  
Storm Event ◽  
Storm Events ◽  
Global Circulation Model

<div> <p>We investigate the evolving water vapour and hydrogen distribution in the martian atmosphere and their associated effect on hydrogen escape during the Mars Year (MY) 34 C storm (a late winter regional dust storm that occurs every Mars year). Improved calculation of the integrated loss of water throughout Mars‘ history (that is currently not well constrained) is possible through tracking the water loss through time from global simulations constrained by available observations. Through constraining water loss we can provide better insight into planetary evolution.</p> <p>The Open University modelling group global circulation model is combined with retrievals from the ExoMars Trace Gas Orbiter (temperature and water vapour profiles from the Atmospheric Chemistry Suite and water vapour profiles from the Nadir and Occultation for Mars Discovery instrument) and the Mars Climate Sounder (temperature profiles and dust column) on the Mars Reconnaissance Orbiter. This multi-spacecraft assimilation provides the best possible replication of the evolving lower atmosphere.</p> <p>The unusually intense dusty conditions during the MY 34 C storm led to increased amounts of water vapour and hydrogen above 80 km compared to a more typical C storm, which had an important impact on the amount of water escaping Mars’ atmosphere. Modelled hydrogen escape rates during the MY 34 C storm peaked at around 1.4 x 10<sup>9</sup> cm<sup>-2</sup> s<sup>-1</sup>, three times the escape rate calculated in the MY 30 C storm scenario and equivalent to those found during previous global-scale dust storms. The weak MY 30 C storm and strong MY 34 C storm can be seen as a bracketing pair of events and therefore the calculated escape rates represent the interannual variabiity expected during C storm events.</p> <p>Our results indicate water loss during the C storm event each year is highly variable, and must be considered when calculating the integrated loss of water through Mars’ history.</p> </div>

Synergistic studies enhanced through data assimilation: combining multiple retrievals with a Mars Global Circulation Model

2021 ◽  
Author(s):  
James Holmes ◽  
Stephen Lewis ◽  
Manish Patel ◽  
Paul Streeter ◽  
Kylash Rajendran
Keyword(s):  
Carbon Monoxide ◽  
Data Assimilation ◽  
Water Vapour ◽  
Circulation Model ◽  
Martian Atmosphere ◽  
Sources Of Information ◽  
Global Circulation Model ◽  
Martian Surface ◽  
Reanalysis Dataset ◽  
Global Circulation

<div> <p><span data-contrast="auto">The wealth of observations now available from multiple spacecraft in orbit around Mars and rovers/landers on the surface provides information on several aspects of the atmosphere, although they are restricted in space and time. Most of the observational datasets are largely complementary, so an efficient method to combine them in a physically consistent way will lead to more constrained studies of the evolution of the global martian atmosphere. Data assimilation is one such method, combining multiple retrievals with a Mars Global Circulation Model (GCM) while accounting for errors in both sources of information and producing an optimal representation of the evolving martian surface and atmosphere. Data assimilation is a powerful tool in that multiple parameters each observed independently by different instruments (e.g. water vapour, ozone, carbon monoxide, dust opacity, temperature) are all realistically constrained and physically consistent at the same time, and unobserved parameters can also be influenced by assimilated data (e.g. water vapour assimilation will impact on the water ice distribution). It also allows for study of atmospheric features that change significantly between observations and identifying processes that lead to the observed changes.</span><span data-ccp-props="{"335551550":6,"335551620":6}"> </span></p> </div> <div> <p><span data-contrast="auto">Data assimilation studies are prevalent on Earth and are becoming more mainstream for Mars, with several different Mars GCMs now capable of assimilating retrievals using different assimilation schemes. The Open University (OU) ExoMars modelling group Mars GCM has been combined with several retrieval datasets via data assimilation to study features of the ozone, carbon monoxide, water and dust cycles alongside dynamical features such as the polar vortices, surface warming during a global dust storm and planetary waves. OpenMARS (Open access to Mars Assimilated Remote Soundings), a publicly available global reanalysis dataset from 1999-2015, was also created using the OU assimilation system.</span><span data-ccp-props="{"335551550":6,"335551620":6}"> </span></p> </div> <div> <p><span data-contrast="auto">This talk will give a brief overview of the benefits and limitations of data assimilation for Mars, and will demonstrate how combining retrievals of different atmospheric parameters with a Mars GCM via data assimilation leads to a better constrained analysis of the martian atmosphere than is possible with retrievals or GCMs alone.</span><span data-ccp-props="{"335551550":6,"335551620":6}"> </span></p> </div>

Formation of the double stratopause and elevated stratopause associated with the major stratospheric sudden warming in 2018/19

2021 ◽  
Author(s):  
Haruka Okui ◽  
Kaoru Sato ◽  
Dai Koshin ◽  
Shingo Watanabe
Keyword(s):  
General Circulation ◽  
Middle Atmosphere ◽  
Baroclinic Instability ◽  
Lower Thermosphere ◽  
Circulation Model ◽  
Lower Atmosphere ◽  
Temperature Structure ◽  
Residual Circulation ◽  
Stratospheric Sudden Warming

<p>After several recent stratospheric sudden warming (SSW) events, the stratopause disappeared and reformed at a higher altitude, forming an elevated stratopause (ES). The relative roles of atmospheric waves in the mechanism of ES formation are still not fully understood. We performed a hindcast of the 2018/19 SSW event using a gravity-wave (GW) permitting general circulation model containing the mesosphere and lower thermosphere (MLT), and analyzed dynamical phenomena throughout the entire middle atmosphere. An ES formed after the major warming on 1 January 2019. There was a marked temperature maximum in the polar upper mesosphere around 28 December 2018 prior to the disappearance of the descending stratopause associated with the SSW. This temperature structure with two maxima in the vertical is referred to as a double stratopause (DS). We showed that adiabatic heating from the residual circulation driven by GW forcing (GWF) causes barotropic and/or baroclinic instability before DS formation, causing in situ generation of planetary waves (PWs). These PWs propagate into the MLT and exert negative forcing, which contributes to DS formation. Both negative GWF and PWF above the recovered eastward jet play crucial roles in ES formation. The altitude of the recovered eastward jet, which regulates GWF and PWF height, is likely affected by the DS structure. Simple vertical propagation from the lower atmosphere is insufficient to explain the presence of the GWs observed in this event.</p>

scholarly journals Simulation of the isotopic composition of stratospheric water vapour – Part 1: Description and evaluation of the EMAC model

2015 ◽  
Vol 15 (10) ◽  
pp. 5537-5555 ◽  
Author(s):  
R. Eichinger ◽  
P. Jöckel ◽  
S. Brinkop ◽  
M. Werner ◽  
S. Lossow
Keyword(s):  
Isotopic Composition ◽  
Water Vapour ◽  
General Circulation ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Circulation Model ◽  
Isotope Ratios ◽  
Physical Fractionation ◽  
Water Isotopologues ◽  
Stratospheric Water Vapour

Abstract. This modelling study aims at an improved understanding of the processes that determine the water vapour budget in the stratosphere by means of the investigation of water isotope ratios. An additional (and separate from the actual) hydrological cycle has been introduced into the chemistry–climate model EMAC, including the water isotopologues HDO and H218O and their physical fractionation processes. Additionally an explicit computation of the contribution of methane oxidation to H2O and HDO has been incorporated. The model expansions allow detailed analyses of water vapour and its isotope ratio with respect to deuterium throughout the stratosphere and in the transition region to the troposphere. In order to assure the correct representation of the water isotopologues in the model's hydrological cycle, the expanded system has been evaluated in several steps. The physical fractionation effects have been evaluated by comparison of the simulated isotopic composition of precipitation with measurements from a ground-based network (GNIP) and with the results from the isotopologue-enabled general circulation model ECHAM5-wiso. The model's representation of the chemical HDO precursor CH3D in the stratosphere has been confirmed by a comparison with chemical transport models (1-D, CHEM2D) and measurements from radiosonde flights. Finally, the simulated stratospheric HDO and the isotopic composition of water vapour have been evaluated, with respect to retrievals from three different satellite instruments (MIPAS, ACE-FTS, SMR). Discrepancies in stratospheric water vapour isotope ratios between two of the three satellite retrievals can now partly be explained.

Aerosol Data Assimilation Using Data from Fengyun-3A and MODIS: Application to a Dust Storm over East Asia in 2011

2018 ◽  
Vol 36 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Xiaoli Xia ◽  
Jinzhong Min ◽  
Feifei Shen ◽  
Yuanbing Wang ◽  
Chun Yang
Keyword(s):  
Data Assimilation ◽  
East Asia ◽  
Dust Storm ◽  
Using Data

scholarly journals The Effects of Assimilating Conventional and ATOVS Data on Forecasted Near-Surface Wind with WRF-3DVAR

2015 ◽  
Vol 143 (1) ◽  
pp. 153-164 ◽  
Author(s):  
Feimin Zhang ◽  
Yi Yang ◽  
Chenghai Wang
Keyword(s):  
Data Assimilation ◽  
Surface Wind ◽  
Lower Atmosphere ◽  
Observation Data ◽  
Initial Field ◽  
Infrared Observation ◽  
Forecast Performance ◽  
Near Surface ◽  
The Impact ◽  
Positive Effect

Abstract In this paper, the Weather Research and Forecasting (WRF) Model with the three-dimensional variational data assimilation (WRF-3DVAR) system is used to investigate the impact on the near-surface wind forecast of assimilating both conventional data and Advanced Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder (ATOVS) radiances compared with assimilating conventional data only. The results show that the quality of the initial field and the forecast performance of wind in the lower atmosphere are improved in both assimilation cases. Assimilation results capture the spatial distribution of the wind speed, and the observation data assimilation has a positive effect on near-surface wind forecasts. Although the impacts of assimilating ATOVS radiances on near-surface wind forecasts are limited, the fine structure of local weather systems illustrated by the WRF-3DVAR system suggests that assimilating ATOVS radiances has a positive effect on the near-surface wind forecast under conditions that ATOVS radiances in the initial condition are properly amplified. Assimilating conventional data is an effective approach for improving the forecast of the near-surface wind.

scholarly journals Turbulence and diffusion in the lower atmosphere

1946 ◽  
Vol 186 (1004) ◽  
pp. 20-35 ◽  
Keyword(s):  
Water Vapour ◽  
Atmospheric Turbulence ◽  
Classical Theory ◽  
Quantitative Approach ◽  
Lower Atmosphere ◽  
Mixing Length ◽  
Self Consistent ◽  
Consistent Treatment ◽  
And Diffusion ◽  
Turbulence And Diffusion

The only existing theory of atmospheric turbulence which is capable of giving a quantitative approach to the complex problems of diffusion in the lower atmosphere is the classical theory in which it is generally assumed that the effect of eddies in the atmosphere is completely analogous to that of molecules in a gas apart from a difference of scale. This assumption, which later evidence has shown to be incorrect, is not essential to the theory, and in the present paper is replaced by the assumption that the mixing length of an eddy increases with both height above and nature of the earth’s surface . With this assumption a self-consistent treatment of diffusion is developed which is able to account quantitatively for such meteorological phenomena as the distribution of water vapour over land and sea (including evaporation from the oceans) and the diffusion of smoke near the ground. The treatment is mainly confined to diffusion in an adiabatic atmosphere.

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