Martian Meteorology: Martian Meteorology: Insights from the Phoenix Mission to the Insights from the Phoenix Mission to the

Martian ArcticMartian Arctic

John E. MooresJohn E. MooresApril 15, 2009April 15, 2009

Talk RoadmapTalk Roadmap Mars Primer, Phoenix Mission Mars Primer, Phoenix Mission

BackgroundBackground

The Surface Stereo Imager (SSI) DataThe Surface Stereo Imager (SSI) Data Supra-Horizon MoviesSupra-Horizon Movies Zenith MoviesZenith Movies Wind Telltale MirrorWind Telltale Mirror

Winds and Blowing DustWinds and Blowing Dust

Clouds and Water IceClouds and Water Ice

Trends and ConclusionsTrends and Conclusions

Why do we care?Why do we care? Understanding the behaviour of wind, water and dust at Understanding the behaviour of wind, water and dust at

the landing site the landing site Why we see what we see locallyWhy we see what we see locally Compliment to LIDAR observationsCompliment to LIDAR observations

Inputs to Modelling EffortsInputs to Modelling Efforts Direct observation of atmospheric parameters helps to refine the Direct observation of atmospheric parameters helps to refine the

big picture of past and present climate on Marsbig picture of past and present climate on Mars Observations may be applicable to the terrestrial stratosphereObservations may be applicable to the terrestrial stratosphere

Pure interestPure interest Animations of cloud help us to understand extraterrestrial Animations of cloud help us to understand extraterrestrial

weather from the human scaleweather from the human scale Must not let terrestrial analogs overcome the dataMust not let terrestrial analogs overcome the data

Mars PrimerMars Primer 44thth planet from the sun planet from the sun

Smaller than EarthSmaller than Earth

Atmospheric pressure is 6 mBar (600hPa)Atmospheric pressure is 6 mBar (600hPa) Main constituents are CO2 (95%) N2 (2.7%) and Ar (1.6%)Main constituents are CO2 (95%) N2 (2.7%) and Ar (1.6%) Up to 100 pUp to 100 pµm of water vaporµm of water vapor

Seasonal cycle is more extreme than the Earth due toSeasonal cycle is more extreme than the Earth due to high orbital eccentricity (9%)high orbital eccentricity (9%) Similar axial tilt (25.4°)Similar axial tilt (25.4°) The atmosphere condenses The atmosphere condenses

seasonably at the winter poleseasonably at the winter pole

Most water is contained in two polar caps, Most water is contained in two polar caps, though much more may be buried in a deep though much more may be buried in a deep cryospherecryosphere

The surface is blanketed by superfine dust The surface is blanketed by superfine dust (1.6 micron radius) which gives the planet (1.6 micron radius) which gives the planet and the sky its colourand the sky its colour

The Phoenix MissionThe Phoenix Mission First mission to the Martian Arctic!First mission to the Martian Arctic!

Hundreds of Scientists, Engineers and students Hundreds of Scientists, Engineers and students came together in Tucson, AZ over the summer came together in Tucson, AZ over the summer of 2008 to run the missionof 2008 to run the mission

Some were present to study data, Some were present to study data, others to resolve hardware issues, but others to resolve hardware issues, but many had specific day to day many had specific day to day operational rolesoperational roles

Lived on “Mars Time” for almost three monthsLived on “Mars Time” for almost three months Martian day is 24hours and 39minutesMartian day is 24hours and 39minutes

Each and every sol produced debate about where to focus the next sol's Each and every sol produced debate about where to focus the next sol's resourcesresources

Investigations had to fit into tight constraints of power, data volume, Investigations had to fit into tight constraints of power, data volume, temperature and workloadtemperature and workload

Not every desire could be accommodatedNot every desire could be accommodated

Launch to LandingLaunch to Landing Launched in July of 2007Launched in July of 2007

9 month interplanetary cruise9 month interplanetary cruise ““7 minutes of terror”7 minutes of terror”

Landed on May 25Landed on May 25thth, 2008, 2008 late northern hemisphere spring late northern hemisphere spring (L(LSS=76.74=76.74°)°) Measurements were taken for 151 Sols (Martian days)Measurements were taken for 151 Sols (Martian days)

Single Lander at 68Single Lander at 68°° N, 125 N, 125°° W W Equivalent to the Mackenzie River Delta on EarthEquivalent to the Mackenzie River Delta on Earth

Barry Goldstein – Project ManagerGlenn Knosp – Project Business Manager

CDR 50 DaysATLO 196 DaysShip 596 DaysLaunch 675 DaysEDL 971 Days

Surface Stereo Imager

MET mast(Temp/Wind)

MECA: microscopy, electro-chemistry, conductivity

TEGA: Thermal and EvolvedGas Analyzer

LIDAR

Robotic ArmIce tool, scraper blades

RA Camera

Thermal and Electrical conductivity probe

The Spacecraft

Major Mission FirstsMajor Mission Firsts Physical Chemistry/GeologyPhysical Chemistry/Geology

Trenched the regolith down to sublimating ice and icy Trenched the regolith down to sublimating ice and icy soilsoil

ChemistryChemistry Detection of a highly oxidizing compound, a perchlorateDetection of a highly oxidizing compound, a perchlorate Detection of carbonates without significant sulfatesDetection of carbonates without significant sulfates

AtmosphereAtmosphere First Mars operation of an Atmospheric LIDARFirst Mars operation of an Atmospheric LIDAR Detection of virga and falling snowDetection of virga and falling snow

The Surface Stereo Imager The Surface Stereo Imager and the Atmospheric Datasetsand the Atmospheric Datasets

Making movies on MarsMaking movies on Mars

Surface Stereo ImagerSurface Stereo Imager Co-I: Mark Lemmon, built at the Co-I: Mark Lemmon, built at the

University of ArizonaUniversity of Arizona

Based on the Imager for Mars Based on the Imager for Mars PathfinderPathfinder

Camera head sits on 84cm Camera head sits on 84cm extendable mastextendable mast

Eyes set 15cm apartEyes set 15cm apart FOV: 13.8 degreesFOV: 13.8 degrees ““Cross-eyed”Cross-eyed”

Two 1024x1024 MER flight Two 1024x1024 MER flight spare CCDsspare CCDs

Excellent S/N at Martian Excellent S/N at Martian Temperatures Temperatures (<1DN/100ms)(<1DN/100ms)

12 filters for each eye from 12 filters for each eye from violet to NIRviolet to NIR

Atmospheric DatasetsAtmospheric Datasets Zenith MoviesZenith Movies

SSI Camera pointed nearly vertically, 10 frame capturesSSI Camera pointed nearly vertically, 10 frame captures Differential Frames to bring out contrast and movement in the atmosphereDifferential Frames to bring out contrast and movement in the atmosphere Many bispectral datasetsMany bispectral datasets Captures the direction of winds aloftCaptures the direction of winds aloft Captures spectral data to differentiate between ice and dust in the Captures spectral data to differentiate between ice and dust in the

atmosphereatmosphere

Supra-Horizon MoviesSupra-Horizon Movies Identical to Zenith Movies, except pointed just above the horizonIdentical to Zenith Movies, except pointed just above the horizon Longest path length through the atmosphereLongest path length through the atmosphere Good for determining morphologiesGood for determining morphologies Can detect atmospheric layering and wind shearCan detect atmospheric layering and wind shear Also captures spectral data for particle differentiationAlso captures spectral data for particle differentiation

Telltale Mirror AnalysisTelltale Mirror Analysis 7441 images taken over the course of the mission7441 images taken over the course of the mission

LIDAR and Winds AloftLIDAR and Winds Aloft Zenith movies can directly Zenith movies can directly

measure the direction of measure the direction of features moving aloft features moving aloft

LIDAR input is required to LIDAR input is required to determine the height of featuresdetermine the height of features

Using the height of greatest Using the height of greatest backscatterbackscatter

Agrees well with the pixels Agrees well with the pixels around the zenitharound the zenith

Still leaves a great deal of errorStill leaves a great deal of error Precise heights may not be Precise heights may not be

known (ranges only)known (ranges only) SSI is limited in the range of SSI is limited in the range of

speeds that are calculablespeeds that are calculable Selection Biases for overlapsSelection Biases for overlaps

2:21 2:24 2:27 2:30 2:33 2:36

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Sol 095, Co-add Radius of 10 pixels

Blue to Red RatiosBlue to Red Ratios Martian Atmosphere is coloured red Martian Atmosphere is coloured red

by the presence of dustby the presence of dust Well understood particle size (1.6Well understood particle size (1.6µm µm

radius)radius) from Viking, MPF, MER from Viking, MPF, MER

Larger particles, such as water ice, Larger particles, such as water ice, will scatter more isotropicallywill scatter more isotropically

Flatter spectral profileFlatter spectral profile Higher signal in the blue compared to Higher signal in the blue compared to

dustdust

By dividing what we see at two By dividing what we see at two spectral points by what we expect can spectral points by what we expect can derive a blue to red ratioderive a blue to red ratio

However, there is a fair bit of spectral However, there is a fair bit of spectral variation across the skyvariation across the sky

Must be compensated for using a Must be compensated for using a radiative transfer coderadiative transfer code

Results for Blowing DustResults for Blowing Dust

Insights from Zenith Movies Insights from Zenith Movies

and Telltale Mirror Analysisand Telltale Mirror Analysis

Dust in the BackgroundDust in the Background Dust is a constant feature of the Dust is a constant feature of the

martian atmosphere and gives martian atmosphere and gives the sky (and the surface) its red the sky (and the surface) its red colourcolour

Dust is distributed relatively evenly in the lower atmosphere

Features can be formed by density variations at different altitudes Gives rise to “billowy” features

Optical depth trend over the course of the mission. Courtesy of Mark

Lemmon

Zenith movies of DustZenith movies of Dust Some interesting zenith movies show the nature of the Some interesting zenith movies show the nature of the

blowing dustblowing dust

Sol 008 Sol 009 Sol 054

Wind DirectionsWind Directions The direction of the winds aloft and at the surface appear to be The direction of the winds aloft and at the surface appear to be

correlatedcorrelated

Wind SpeedsWind Speeds Even with LIDAR difficult to get wind speed aloftEven with LIDAR difficult to get wind speed aloft

Tried correlating Tried correlating the wind speed the wind speed withwith

Time of DayTime of Day Sol of MissionSol of Mission AltitudeAltitude

Altitude only Altitude only relationship relationship showing a showing a reasonable reasonable correlationcorrelation

Not unexpectedNot unexpected Saturated region Saturated region

highlightedhighlighted 2 populations, 2 populations,

dust and clouddust and cloud

Telltale MirrorTelltale Mirror

Diurnal Trend in Diurnal Trend in Dust loading is also Dust loading is also seen in the fractional seen in the fractional coverage of the coverage of the telltale mirrortelltale mirror

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Time of Day

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be seen at 12:00 or 15:00• Mirror accumulates dust

in wind shadows

Closer look at the patternsCloser look at the patterns Sol 029 “hecto-Sol 029 “hecto-

telltale” 100 frames telltale” 100 frames captured near the captured near the turn-around time turn-around time show increased show increased variability after 13:00 variability after 13:00 LTSTLTST

12.4 12.6 12.8 13 13.2 13.4 13.6

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Fractional Coverage of the Telltale Mirror by DustSol 029 100-Frame Telltale

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• Mission-long trends with the diurnal effect removed show little variability

• Thus the Diurnal trend Dominates• More consistent with

wind scour then quiescent settling

Results for Water Ice CloudResults for Water Ice Cloud

Insights from Zenith Insights from Zenith and Supra-Horizon Moviesand Supra-Horizon Movies

Water Ice in the Martian AtmosphereWater Ice in the Martian Atmosphere Phoenix was first to observe martian snowfall, but putative water ice clouds Phoenix was first to observe martian snowfall, but putative water ice clouds

have been seen beforehave been seen before Diurnal cloud patterns on the larger volcanosDiurnal cloud patterns on the larger volcanos Formation of a polar hoodFormation of a polar hood Cloud inferred from TIR and direct sensing with MOLACloud inferred from TIR and direct sensing with MOLA

The water ice clouds are largely absent for the first 79 sols of the missionThe water ice clouds are largely absent for the first 79 sols of the mission Supra-Horizon movies show some possible very thin clouds as early as the 60sSupra-Horizon movies show some possible very thin clouds as early as the 60s

Cirrus Clouds photographed by Opportunity rover at Endurance Crater

Supra Horizon Cloud Supra Horizon Cloud MorphologiesMorphologies

Higher level regular Higher level regular clouds are common clouds are common features in the features in the supra-horizon supra-horizon moviesmovies

Sol 78

Supra Horizon Cloud Supra Horizon Cloud MorphologiesMorphologies

Starting on sol 94, Starting on sol 94, optically thick, fluffier, optically thick, fluffier, more cumulus-like more cumulus-like clouds are evidentclouds are evident

These clouds have These clouds have pronounced blue to pronounced blue to red ratiosred ratios

Sol 94

Supra Horizon Cloud Supra Horizon Cloud MorphologiesMorphologies

They have also been They have also been seen to form and seen to form and sublimate from locally sublimate from locally available water vapouravailable water vapour

Sol 112

Supra Horizon Cloud Supra Horizon Cloud MorphologiesMorphologies

Morphologically distinct, Morphologically distinct, streaky clouds are seen streaky clouds are seen at night during the at night during the middle of the missionmiddle of the mission

Sol 84

Supra Horizon Cloud Supra Horizon Cloud MorphologiesMorphologies

The cloud-forms get The cloud-forms get increasingly complex, increasingly complex, optically thick and optically thick and appear to move faster appear to move faster across the sky as the across the sky as the mission progressesmission progresses

But some days But some days remain relatively dryremain relatively dry

Sol 132 Sol 148

Zenith movies of Water IceZenith movies of Water Ice

Zenith movies Zenith movies also show water also show water ice cloudice cloud

Non-ideal Non-ideal viewing geometryviewing geometry

Can still get blue Can still get blue to red ratios out to red ratios out of the dataof the data

Sol 101 Sol 141

Seasonal TrendSeasonal Trend

Quantitative: Blue to Red Ratios Quantitative: Blue to Red Ratios confirm more water ice later in the confirm more water ice later in the missionmission

Time-Varying Component has Time-Varying Component has bigger increase then mean framebigger increase then mean frame

Variability: Late in the mission Variability: Late in the mission there continue to be days when there continue to be days when the BRR is lowthe BRR is low

Also the dust remains a Also the dust remains a significant atmospheric significant atmospheric componentcomponent BRRs from Supra-Horizon BRRs from Supra-Horizon

Movies plot lower then for Movies plot lower then for Zenith MoviesZenith Movies

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Diurnal TrendDiurnal Trend

A strong diurnal trend is also visibleA strong diurnal trend is also visible A peak in cloudiness is observed around A peak in cloudiness is observed around

mid-daymid-day Variable cloudiness in the early morning? Variable cloudiness in the early morning?

(Selection bias effect)(Selection bias effect)

The formation of cloud is inhibited in the The formation of cloud is inhibited in the early afternoon and eveningearly afternoon and evening

Sublimation?Sublimation? Out of Water Vapor?Out of Water Vapor? Boundary Layer decoupling? Boundary Layer decoupling?

(formation of an intermediate stable layer)(formation of an intermediate stable layer)

The trend is also seen in the last 20 sols The trend is also seen in the last 20 sols of the missionof the mission

Some days have strong cloud at middaySome days have strong cloud at midday On some days cloud is absentOn some days cloud is absent

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Extension to the first 50 solsExtension to the first 50 sols The Signal to Background ratio corresponds to the BRR of the Time The Signal to Background ratio corresponds to the BRR of the Time

Variable ComponentVariable Component Can use the Signal to Background ratio to get an idea of cloudiness early in the Can use the Signal to Background ratio to get an idea of cloudiness early in the

missionmission A possible minimum is observed near sol 50 with water ice ramping up starting A possible minimum is observed near sol 50 with water ice ramping up starting

near sol 80near sol 80

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VirgaVirga

LIDAR has seen LIDAR has seen evidence of fall evidence of fall streaks at night, streaks at night, characteristic of Virgacharacteristic of Virga

The SSI has also The SSI has also observed this observed this behaviour on several behaviour on several occasions during the occasions during the day in Supra-Horizon day in Supra-Horizon moviesmovies

Sol 126 Sol 80

Observed Wind ShearObserved Wind Shear Recall: Winds aloft match well with winds at the surfaceRecall: Winds aloft match well with winds at the surface

Correspondence is good early in the mission when dusty conditions Correspondence is good early in the mission when dusty conditions dominatedominate

Later in the mission many features pass by too rapidly to observeLater in the mission many features pass by too rapidly to observe

However, several supra-horizon movies show two layers moving at However, several supra-horizon movies show two layers moving at different rates and in different directionsdifferent rates and in different directions Could locally-driven winds be interacting with larger-scale flows?Could locally-driven winds be interacting with larger-scale flows?

Sol 096

Trends and ConclusionsTrends and Conclusions

Summary of ObservationsSummary of Observations Observed a diurnally rotating wind aloft matching with the wind telltaleObserved a diurnally rotating wind aloft matching with the wind telltale

Low-fidelity data for wind speed aloft shows no evidence for higher wind Low-fidelity data for wind speed aloft shows no evidence for higher wind speeds aloftspeeds aloft

Dustiness of the wind telltale mirror shows a diurnal pattern consistent with Dustiness of the wind telltale mirror shows a diurnal pattern consistent with wind deposition and scour instead of settlingwind deposition and scour instead of settling

Variation in morphologies of cloud indicate an active hydrological cycleVariation in morphologies of cloud indicate an active hydrological cycle

Clouds have high BRRs, likely made of relatively large particlesClouds have high BRRs, likely made of relatively large particles

BRRs have a diurnal trend peaking around 10:00 to 12:00 LTSTBRRs have a diurnal trend peaking around 10:00 to 12:00 LTST

BRRs and Time-Varying Signal Strength are correlated and have a BRRs and Time-Varying Signal Strength are correlated and have a minimum near sol 50minimum near sol 50

BRRs increase from sol 50 to sol 150 but show significant day to day BRRs increase from sol 50 to sol 150 but show significant day to day variabilityvariability

Virga and differential motion of cloud layers have been observedVirga and differential motion of cloud layers have been observed

Significance of TrendsSignificance of Trends Strongly expressed diurnal cycle in wind, dust Strongly expressed diurnal cycle in wind, dust

movement and atmospheric water icemovement and atmospheric water ice Suggests the water and temperature cycles are Suggests the water and temperature cycles are

dominated by local effects instead of transportdominated by local effects instead of transport Consistent with water and much of the dust being Consistent with water and much of the dust being

confined to the PBL (LIDAR) and consistent surface confined to the PBL (LIDAR) and consistent surface air temperaturesair temperatures

Strongly expressed seasonal increase in atmospheric Strongly expressed seasonal increase in atmospheric water icewater ice

Progressively colder atmospheric temperatures later Progressively colder atmospheric temperatures later in the summer allow for more expression of cloud in the summer allow for more expression of cloud even with declining water vaporeven with declining water vapor

Exceptions to the RuleExceptions to the Rule

Some significant variability exists in the seasonal Some significant variability exists in the seasonal datasetdataset

Very “dry” days can be seen late in the summer Very “dry” days can be seen late in the summer when cloud is increasingwhen cloud is increasing

Wind shear and multiple movements at different Wind shear and multiple movements at different heights appear to be present occasionallyheights appear to be present occasionally

Argues for not insignificant regional transport of Argues for not insignificant regional transport of water ice/vaporwater ice/vapor

Thank-you!Thank-you!