On the Structure and Dynamics of the Martian Middle Atmosphere

Semi-Stationary Waves Masquerading as Stationary Waves in the Martian AtmosphereTamara McDunn1

Advisor: David Kass1

1Jet Propulsion Laboratory, California Institute of Technology

JPL Postdoc Seminar, June 27, 2013CL#13-1687(c) 2013 California Institute of Technology. Government sponsorship acknowledged.

1Outline6/27/132/28Background on stationary waves at MarsMars Climate Sounder datasetTraditional analysis and its limitation Behavior of wavenumber-2 semi-stationary waves at Mars ConclusionsFuture Work2Background6/27/133/28Waves are a fundamental feature of an atmosphere on a rotating body; they drive atmospheric behavior and can be used as a diagnostic of that behavior

7 martian years of nearly-continuous lower-atmosphere (surface to ~50 km) observations

Seasonal behavior of large-scale (planetary) waves has been well-explored using orbital observations; short-timescale behavior has not

3Stationary Waves6/27/134/28Waves with zero temporal frequency in the zonal direction (W-E)

Forced by flow over topography and zonal inhomogeneities in thermal forcing

Phase is approximately constant with height and season

On Earth they often generate clouds

4Effects of Stationary Waves on Earth6/27/135/28Redistribute heat from low to high latitudes

Reduce atmospheric stability (resistance to vertical motion)

Deposit momentum at high altitudes leading to acceleration/deceleration of the mean flow

5Behavior of Stationary Waves at Mars6/27/136/28Amplitudes peak during local fall and winter

Amplitudes peak at mid-latitudes (edge of circumpolar jet)

Dominant zonal wavenumber is driven by form of topography at jet latitudes

Track edge of polar vortex (move poleward with height)

Same effects as stationary waves on Earth6Example6/27/137/28

7Model: Mars Climate Database6/27/138/28Suite of simulations from a general circulation model [Lewis et al. 1999]

Horizontal resolution: 3.75 x 5.625

Vertical resolution: variable (12 layers in lowest scale height, ~1/3 scale height to scale height above that)

Forced with moderate solar input

Forced with climatological distribution of suspended dust (TES year 1)8Outline6/27/139/28Background on stationary waves at MarsMars Climate Sounder datasetTraditional analysis and its limitation Behavior of wavenumber-2 semi-stationary waves at Mars ConclusionsFuture Work9ParameterProperty / Performance

Instrument TypeFilter RadiometerSpectral Range & Channels0.3 to 50.0 m in nine spectral channelsTelescopesTwo identical, 4cm aperture, f/1.6 telescopesDetectorsNine, 21-element, linear thermopile arrays at 300 KFields-of-ViewDetector IFOV:3.6 x 6.2mrad5.0 x 8.6 km(At Limb)Instrument IFOV:75 x 75mrad105 x 105km(At Limb)Instrument ArticulationTwo-axis azimuth/elevationRange/Resolution:Azimuth:270/0.1 degreesElevation:270/0.1 degreesOperation ModesSingle Operating Mode, 2 s signal integration periodObservation StrategyLimb Staring; Limb, nadir & off-nadir scanningIn-track, Cross-track, and Off-track viewing6/27/1310Mars Climate Sounder (MCS) Instrument Description

ThermalBlanketsTelescopesSolar TargetAzimuthActuatorElevationActuatorAzimuthYokeBlackbodyTargets

LimbNadir10MCS Spectral Channel CharacteristicsTelescope/BandpassBandMeasurement FunctionChannel #cm-1 Center - mA1595 - 61516.5Temperature 0-20 kmA2615 - 64515.9Temperature 20-40 km, PressureA3635 - 66515.4Temperature 40-80 km, Pressure A4820 - 87011.8Dust and Condensate (D&C) extinction 0-80 kmA5400 - 50022.2D&C extinction 0-80 kmA63300 - 330001.65Polar Radiative BalanceB1290 - 34031.7Surface Temperature, D&C extinction 0-80 kmB2220 - 26041.7Water Vapor 0-40 km, D&C extinction 0-80 kmB3230 - 24542.1Water Vapor 0-40 km, D&C extinction 0-80 km6/27/1311/2811MCS DatasetRetrieved profiles: p, T, water ice, dustSurface to 80-90 km (5 km resolution)Sun-synchronous, fixed, high-inc., polar orbit3 am and 3 pmT uncertainty ~ 2 K

6/27/1312/28

McCleese et al., 2007; Kleinbhl et al., 2009; 2011

0 30 60 90 120 150 180 210 240 270 300 330 360Areocentric Longitude of the Sun (Ls) - Degrees9.59.08.58.07.57.06.56.09.59.08.58.07.57.06.56.09.59.08.58.07.57.06.56.09.59.08.58.07.57.06.56.0Pressure mbar Pressure mbar Pressure mbar Pressure mbarMCS Investigation Timeline13Outline6/27/1314/28Background on stationary waves at MarsMars Climate Sounder datasetTraditional analysis and its limitation Behavior of wavenumber-2 semi-stationary waves at Mars ConclusionsFuture Work14Traditional AnalysisStep 1: Compute Tavg and Tdiff6/27/1315/28 Tavg = T3am + T3pm 2 Tdiff = T3am - T3pm 2e.g., Banfield et al, 2003; Lee et al, 2009 m = |s |local-time wavenumberzonal wavenumbertemporal frequency Step 2: Take spatial Fourier Transform15

Ls = 285, Lat = 45 N, and p = 106 Pa6/27/1316/28Result of Traditional Analysis

Local-time wavenumber Local-time wavenumberWave Amplitude (K) Tavg Tdiff 17/28Limitation of Traditional Analysis LT = 03 LT = 156/27/13

m = 2 iis strong on the nightside but, disappears on the dayside

Ls = 285 LatitudeLatitudeOutline6/27/1318/28Background on stationary waves at MarsMars Climate Sounder datasetTraditional analysis and its limitation Behavior of wavenumber-2 semi-stationary waves at Mars ConclusionsFuture Work18Local-time Behavior (from model)6/27/1319/28 LT = 00

Pressure (Pa)19Local-time Behavior (from model)6/27/1320/28 LT = 01

Pressure (Pa)20Local-time Behavior (from model)6/27/1319/28 LT = 02

Pressure (Pa)21Local-time Behavior (from model)6/27/1319/28 LT = 03

Pressure (Pa)22Local-time Behavior (from model)6/27/1319/28 LT = 04

Pressure (Pa)23Local-time Behavior (from model)6/27/1319/28 LT = 05

Pressure (Pa)24Local-time Behavior (from model)6/27/1319/28 LT = 06

Pressure (Pa)25Local-time Behavior (from model)6/27/1319/28 LT = 07

Pressure (Pa)26Local-time Behavior (from model)6/27/1319/28 LT = 08

Pressure (Pa)27Local-time Behavior (from model)6/27/1319/28 LT = 09

Pressure (Pa)28Local-time Behavior (from model)6/27/1319/28 LT = 10

Pressure (Pa)29Local-time Behavior (from model)6/27/1319/28 LT = 11

Pressure (Pa)30Local-time Behavior (from model)6/27/1319/28 LT = 12

Pressure (Pa)31Local-time Behavior (from model)6/27/1319/28 LT = 13

Pressure (Pa)32Local-time Behavior (from model)6/27/1319/28 LT = 14

Pressure (Pa)33Local-time Behavior (from model)6/27/1319/28 LT = 15

Pressure (Pa)34Local-time Behavior (from model)6/27/1319/28 LT = 16

Pressure (Pa)35Local-time Behavior (from model)6/27/1319/28 LT = 17

Pressure (Pa)36Local-time Behavior (from model)6/27/1319/28 LT = 18

Pressure (Pa)37Local-time Behavior (from model)6/27/1319/28 LT = 19

Pressure (Pa)38Local-time Behavior (from model)6/27/1319/28 LT = 20

Pressure (Pa)39Local-time Behavior (from model)6/27/1319/28 LT = 21

Pressure (Pa)40Local-time Behavior (from model)6/27/1319/28 LT = 22

Pressure (Pa)41Local-time Behavior (from model)6/27/1319/28 LT = 23

Pressure (Pa)42Daily Maximum and Minimum(from model)6/27/1320/28

Pressure (Pa) (K)Daily Maximum m = 2 Amplitude Daily Minimum m = 2 Amplitude LT = 00 am LT = 11 amLs = 285 4321/28Latitudinal Behavior (from MCS) T3am , Ls = 285

T3am m = 2 peaks at mid-latitudes and is vertically confined to p ~ 80-150 Pa44

Seasonal Behavior (from MCS)Latitude = 30-40 NLatitude = 40-50 NT3am m = 2 at higher latitudes is greater at local fallT3am m = 2 at lower latitudes is greater at local winter 6/27/1322/28

45Interannual Behavior (from MCS)MY 29MY 30Spatial extent varies, but m = 2 exists during all 3 Mars Years23/286/27/13

MY 28

46Associated with negative phase of Meridional (S-N) Winds (from model)24/286/27/13 Ls = 285, p = 106 Pa

LT = 00 am LT = 11 am

47Outline6/27/1325/28Background on stationary waves at MarsMars Climate Sounder datasetTraditional analysis and its limitation Behavior of wavenumber-2 semi-stationary waves at Mars ConclusionsFuture Work48Semi-stationary waves are those that exhibit Stationary behaviorTavg and Tdiff analyses consistent with m = s = 2 wavesPeak during fall and winter Zonal form matches that of the topography at mid-latitudesPositive phase is in the Lee of Tharsis and Elysium mountain ranges Phase is nearly constant with season and height (not shown)

Non-stationary behaviorLocal-time variability strongest near local midnightweakest near local noonCorrelation with the semidiurnal tide in the v wind fieldUnstable region aloft (not shown)6/27/1326/28ConclusionsStorm Tracks-Positive phase correlated with storm tracks?- Profiles through the positive phase show no significant correlation with dust opacity

Clouds- Profiles through the negative phase show no significant correlation with water ice opacity- But, negative phase is correlated with increased nightside column-integrated water ice clouds [Benson et al., 2011]

Aerosol Transport-Positive phase correlated with channels of transport?

6/27/1327/28Future Work: Explore Implications for Atmosphere

50Thank you! 6/27/1328/28tamara.mcdunn@jpl.nasa.govFunding Acknowledgement:Caltech/JPL Postdoctoral Fellowship