scholarly journals The Emirates Exploration Imager (EXI) Instrument on the Emirates Mars Mission (EMM) Hope Mission

2021 ◽  
Vol 217 (8) ◽  
Author(s):  
A. R. Jones ◽  
M. Wolff ◽  
M. Alshamsi ◽  
M. Osterloo ◽  
P. Bay ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Ice Clouds ◽  
Water Ice ◽  
Mars Mission ◽  
Multiple Observations ◽  
Planetary Rotation ◽  
Temporal And Spatial ◽  
Similar Imaging ◽  
Full Disk ◽  
Framing Camera

AbstractThe Emirates Exploration Imager (EXI) on-board the Emirates Mars Mission (EMM) offers both regional and global imaging capabilities for studies of the Martian atmosphere. EXI is a framing camera with a field-of-view (FOV) that will easily capture the martian disk at the EMM science orbit periapsis. EXI provides 6 bandpasses nominally centered on 220, 260, 320, 437, 546, 635 nm using two telescopes (ultraviolet (UV) and visible(VIS)) with separate optics and detectors. Images of the full-disk are acquired with a resolution of 2–4 km per pixel, where the variation is driven by periapsis and apoapsis points of the orbit, respectively. By combining multiple observations within an orbit with planetary rotation, EXI is able to provide diurnal sampling over most of the planet on the scale of 10 days. As a result, the EXI dataset allows for the delineation of diurnal and seasonal timescales in the behavior of atmospheric constituents such as water ice clouds and ozone.This combination of temporal and spatial distinguishes EXI from somewhat similar imaging systems, including the Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter (MRO) (Malin et al. in Icarus 194(2):501–512, 2008) and the various cameras on-board the Hubble Space Telescope (HST; e.g., James et al. in J. Geophys. Res. 101(E8):18,883–18,890, 1996; Wolff et al. in J. Geophys. Res. 104(E4):9027–9042, 1999). The former, which has comparable spatial and spectral coverage, possesses a limited local time view (e.g., mid-afternoon). The latter, which provides full-disk imaging, has limited spatial resolution through most of the Martian year and is only able to provide (at most) a few observations per year given its role as a dedicated, queue-based astrophysical observatory. In addition to these unique attributes of the EXI observations, the similarities with other missions allows for the leveraging of both past and concurrent observations. For example, with MARCI, one can build on the ∼6 Mars years of daily global UV images as well as those taken concurrently with EXI.

scholarly journals Influence of water ice clouds on Martian tropical atmospheric temperatures

2008 ◽  
Vol 35 (7) ◽  
pp. n/a-n/a ◽  
Author(s):  
R. John Wilson ◽  
Stephen R. Lewis ◽  
Luca Montabone ◽  
Michael D. Smith
Keyword(s):  
Ice Clouds ◽  
Water Ice ◽  
Influence Of Water

A Comparison of Aphelion Cloud Belt Phase Functions Before and After the Mars Year 34 Global Dust Storm

2021 ◽  
Author(s):  
Alex Innanen ◽  
Brittney Cooper ◽  
Charissa Campbell ◽  
Scott Guzewich ◽  
Jacob Kloos ◽  
...  
Keyword(s):  
Dust Storm ◽  
Phase Function ◽  
Dust Storms ◽  
Ice Crystal ◽  
Ice Clouds ◽  
Water Ice ◽  
Ice Cloud ◽  
Sky Survey ◽  
Scattering Phase ◽  
Scattering Phase Function

<p>1. INTRODUCTION</p><p>The Mars Science Laboratory (MSL) is located in Gale Crater (4.5°S, 137.4°E), and has been performing cloud observations for the entirety of its mission, since its landing in 2012 [eg. 1,2,3]. One such observation is the Phase Function Sky Survey (PFSS), developed by Cooper et al [3] and instituted in Mars Year (MY) 34 to determine the scattering phase function of Martian water-ice clouds. The clouds of interest form during the Aphelion Cloud Belt (ACB) season (L<sub>s</sub>=50°-150°), a period of time during which there is an increase in the formation of water-ice clouds around the Martian equator [4]. The PFSS observation was also performed during the MY 35 ACB season and the current MY 36 ACB season.</p><p>Following the MY 34 ACB season, Mars experienced a global dust storm which lasted from L<sub>s</sub>~188° to L<sub>s</sub>~250° of that Mars year [5]. Global dust storms are planet-encircling storms which occur every few Mars years and can significantly impact the atmosphere leading to increased dust aerosol sizes [6], an increase in middle atmosphere water vapour [7], and the formation of unseasonal water-ice clouds [8]. While the decrease in visibility during the global dust storm itself made cloud observation difficult, comparing the scattering phase function prior to and following the global dust storm can help to understand the long-term impacts of global dust storms on water-ice clouds.</p><p>2. METHODS</p><p>The PFSS consists of 9 cloud movies of three frames each, taken using MSL’s navigation cameras, at a variety of pointings in order to observe a large range of scattering angles. The goal of the PFSS is to characterise the scattering properties of water-ice clouds and to determine ice crystal geometry.  In each movie, clouds are identified using mean frame subtraction, and the phase function is computed using the formula derived by Cooper et al [3]. An average phase function can then be computed for the entirety of the ACB season.</p><p><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.eda718c85da062913791261/sdaolpUECMynit/1202CSPE&app=m&a=0&c=67584351a5c2fde95856e0760f04bbf3&ct=x&pn=gnp.elif&d=1" alt="Figure 1 – Temporal Distribution of Phase Function Sky Survey Observations for Mars Years 34 and 35" width="800" height="681"></p><p>Figure 1 shows the temporal distributions of PFSS observations taken during MYs 34 and 35. We aim to capture both morning and afternoon observations in order to study any diurnal variability in water-ice clouds.</p><p>3. RESULTS AND DISCUSSION</p><p>There were a total of 26 PFSS observations taken in MY 35 between L<sub>s</sub>~50°-160°, evenly distributed between AM and PM observations. Typically, times further from local noon (i.e. earlier in the morning or later in the afternoon) show stronger cloud features, and run less risk of being obscured by the presence of the sun. In all movies in which clouds are detected, a phase function can be calculated, and an average phase function determined for the whole ACB season.  </p><p>Future work will look at the water-ice cloud scattering properties for the MY 36 ACB season, allowing us to get more information about the interannual variability of the ACB and to further constrain the ice crystal habit. The PFSS observations will not only assist in our understanding of the long-term atmospheric impacts of global dust storms but also add to a more complete image of time-varying water-ice cloud properties.</p>

Atmospheres on Callisto composed of sublimated water vapor and its photochemical products

2021 ◽  
Author(s):  
Shane Carberry Mogan ◽  
Orenthal Tucker ◽  
Robert Johnson ◽  
Audrey Vorburger ◽  
Andre Galli ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Near Infrared ◽  
Hubble Space Telescope ◽  
Mass Movement ◽  
Complex Surface ◽  
Atmospheric Modeling ◽  
Galilean Satellites ◽  
Geophysical Research ◽  
Water Ice ◽  
Remote Determination

<p class="western" align="justify">The parameter space for the very uncertain composition of sublimated H2O and its photochemical products H and H2 in Callisto's atmosphere is examined using the Direct Simulaton Monte Carlo (DSMC) method.</p> <p class="western" align="justify">We focus on two significantly different versions of H2O production in which:</p> <p class="western" align="justify">(1) the ice and dark, non-ice/ice-poor material are intimately mixed and H2O sublimates at Callisto's warm day-side temperatures (e.g., as in most atmospheric modeling efforts at Callisto to date [1-4]); and</p> <p class="western" align="justify">(2) the ice and dark, non-ice/ice-poor material are segregated (e.g., consistent with interpretations of images of Callisto's surface taken by Voyager [5, 6] and Galileo [7]) and H2O sublimates at "ice" temperatures [8].</p> <p class="western" align="justify">Our 2D molecular kinetic models track the motion H2O, whose sublimation yield varies several orders of magnitude depending on the description of Callisto's surface, its photochemical products H and H2, and a relatively dense O2 component. Whereas H is assumed to react in the regolith on return to the surface, H2 is assumed to thermalize and re-enter the atmosphere.</p> <p class="western" align="justify">We compare the simulated LOS column densities of H to the detected H corona at Callisto [9], which was suggested to be produced primarily by photodissociation of sublimated H2O. Our goal is to use the corona observations to help constrain the source rate for H2O from Callisto’s complex surface.</p> <p class="western" align="justify"><strong>References</strong></p> <p class="western" align="justify">[1] Liang et al., 2005. Atmosphere of Callisto. <em>Journal of Geophysical Research: Planets</em>.</p> <p class="western" align="justify">[2] Vorburger et al., 2015. Monte-Carlo simulation of Callisto’s exosphere. <em>Icarus</em>.</p> <p class="western" align="justify">[3] Hartkorn et al., 2017. Structure and density of Callisto’s atmosphere from a fluid-kinetic model of its ionosphere: Comparison with Hubble Space Telescope and Galileo observations. <em>Icarus.</em></p> <p class="western" align="justify">[4] Carberry Mogan et al., 2021 (<em>under review</em>). A tenuous, collisional atmosphere on Callisto. <em>Icarus</em>.</p> <p class="western" align="justify">[5] Spencer and Maloney, 1984. Mobility of water ice on Callisto: Evidence and implications. <em>Geophysical Research Letters</em>.</p> <p class="western" align="justify">[6] Spencer, 1987. Thermal segregation of water ice on the Galilean satellites. <em>Icarus</em>.</p> <p class="western" align="justify">[7] Moore et al., 1999. Mass movement and landform degradation on the icy Galilean satellites: Results of the Galileo nominal mission. <em>Icarus</em>.</p> <p class="western" align="justify">[8] Grundy et al., 1999. Near-infrared spectra of icy outer solar system surfaces: Remote determination of H2O ice temperatures. <em>Icarus</em>.</p> <p class="western" align="justify">[9] Roth et al., 2017. Detection of a hydrogen corona at Callisto. <em>Journal of Geophysical Research: Planets</em>.</p>

Nighttime convection in water-ice clouds at high northern latitudes on Mars

Icarus ◽  
2021 ◽  
pp. 114693
Author(s):  
David Hinson ◽  
Huiqun Wang ◽  
John Wilson ◽  
Aymeric Spiga
Keyword(s):  
Ice Clouds ◽  
Water Ice ◽  
Northern Latitudes

Investigating the relationship between ozone and water-ice in the martian atmosphere

2020 ◽  
Author(s):  
Megan Brown ◽  
Manish Patel ◽  
Stephen Lewis ◽  
Amel Bennaceur
Keyword(s):  
Carbon Dioxide ◽  
Water Vapour ◽  
Hydroxyl Radicals ◽  
Atmospheric Chemistry ◽  
Martian Atmosphere ◽  
Reaction Rates ◽  
Chemical Processes ◽  
Ice Clouds ◽  
Water Ice ◽  
The Relationship

<p>This project maps ozone and ice-water clouds detected in the martian atmosphere to assess the atmospheric chemistry between ozone, water-ice and hydroxyl radicals. Hydroxyl photochemistry may be indicated by a non-negative or fluctuating correlation between ozone and water-ice. This will contribute to understanding the stability of carbon dioxide and atmospheric chemistry of Mars.</p><p>Ozone (O<sub>3</sub>) can be used for tracking general circulation of the martian atmosphere and other trace chemicals, as well as acting as a proxy for water vapour. The photochemical break down of water vapour produces hydroxyl radicals known to participate in the destruction of ozone. The relationship between water vapour and ozone is therefore negatively correlated. Atmospheric water-ice concentrations may also follow this theory. The photochemical reactions between ozone, water-ice clouds and hydroxyl radicals are poorly understood in the martian atmosphere due to the short half-life and rapid reaction rates of hydroxyl radicals. These reactions destroy ozone, as well as indirectly contributing to the water cycle and stability of carbon dioxide (measured by the CO<sub>2</sub>–CO ratio). However, the detection of ozone in the presence of water-ice clouds suggests the relationship between them is not always anti-correlated. Global climate models (GCMs) struggle to describe the chemical processes occurring within water-ice clouds. For example, the heterogeneous photochemistry described in the LMD (Laboratoire de Météorologie Dynamique) GCM did not significantly improve the model. This leads to the following questions:<em> what is the relationship between water-ice clouds and ozone, and can the chemical reactions of hydroxyl radicals occurring within water-ice clouds be determined through this relationship?</em></p><p>This project aims to address these questions using nadir and occultation retrievals of ozone and water-ice clouds, potentially using retrievals from the UVIS instrument aboard NOMAD (Nadir and Occultation for Mars Discovery), ExoMars Trace Gas Orbiter. Analysis will include temporal and spatial binning of data to help identify any patterns present. Correlation tests will be conducted to determine the significance of any relationship at short term and seasonal scales along a range of zonally averaged latitude photochemical model from the LMD-UK GCM will be used to further explore the chemical processes.</p><p>Interactions between hydroxyl radicals and the surface of water-ice clouds are poorly understood. Ozone abundance is greatest in the winter at the polar regions, which also coincides with the appearance of the polar hood clouds. The use of nadir observations will enable the comparison between total column of ozone abundance at high latitudes (>60°S) in a range of varying water-ice cloud opacities, as well as the equatorial region (30°S – 30°N) during aphelion. Water-ice clouds may remove hydroxyl radicals responsible for the destruction of ozone and thus the previously assumed anticorrelation between ozone and water-ice will not hold. The project will therefore assess the hypothesis that: <em>water-ice clouds may act as a sink for hydroxyl radicals.</em></p>

scholarly journals Simulating Martian boundary layer water ice clouds and the lidar measurements for the Phoenix mission

2008 ◽  
Vol 113 (null) ◽  
Author(s):  
Jagruti Pathak ◽  
Diane V. Michelangeli ◽  
Leonce Komguem ◽  
James Whiteway ◽  
Leslie K. Tamppari
Keyword(s):  
Boundary Layer ◽  
Ice Clouds ◽  
Water Ice ◽  
Lidar Measurements ◽  
Phoenix Mission ◽  
The Phoenix

scholarly journals The Ability of MM5 to Simulate Ice Clouds: Systematic Comparison between Simulated and Measured Fluxes and Lidar/Radar Profiles at the SIRTA Atmospheric Observatory

2006 ◽  
Vol 134 (3) ◽  
pp. 897-918 ◽  
Author(s):  
M. Chiriaco ◽  
R. Vautard ◽  
H. Chepfer ◽  
M. Haeffelin ◽  
J. Dudhia ◽  
...  
Keyword(s):  
Mesoscale Model ◽  
Sedimentation Velocity ◽  
State University ◽  
Pennsylvania State University ◽  
Ice Clouds ◽  
Water Ice ◽  
Fifth Generation ◽  
Profile Inversion ◽  
Selection Of

Abstract The ability of the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) to simulate midlatitude ice clouds is evaluated. Model outputs are compared to long-term meteorological measurements by active (radar and lidar) and passive (infrared and visible fluxes) remote sensing collected at an atmospheric observatory near Paris, France. The goal is to understand which of four microphysical schemes is best suited to simulate midlatitude ice clouds. The methodology consists of simulating instrument observables from the model outputs without any profile inversion, which allows the authors to use fewer assumptions on microphysical and optical properties of ice particles. Among the four schemes compared in the current study, the best observation-to-simulations scores are obtained with Reisner et al. provided that the particles’ sedimentation velocity from Heymsfield and Donner is used instead of that originally proposed. For this last scheme, the model gives results close to the measurements for clouds with medium optical depth of typically 1 to 3, whatever the season. In this configuration, MM5 simulates the presence of midlatitude ice clouds in more than 65% of the authors’ selection of observed cloud cases. In 35% of the cases, the simulated clouds are too persistent whatever the microphysical scheme and tend to produce too much solid water (ice and snow) and not enough liquid water.

scholarly journals Viking era water-ice clouds

2000 ◽  
Vol 105 (E2) ◽  
pp. 4087-4107 ◽  
Author(s):  
Leslie K. Tamppari ◽  
Richard W. Zurek ◽  
David A. Paige
Keyword(s):  
Ice Clouds ◽  
Water Ice
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