Strategy of meteorological study in Venus Climate Orbiter mission
Download
1 / 39

Strategy of meteorological study in Venus Climate Orbiter mission - PowerPoint PPT Presentation


  • 106 Views
  • Uploaded on

Strategy of meteorological study in Venus Climate Orbiter mission. T. Imamura, M. Nakamura Institute of Space and Astronautical Sciences. Venus Climate Orbiter (Planet-C) project: Status and schedule. The VCO mission was approved by the Space Development Committee of the government in 2001.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Strategy of meteorological study in Venus Climate Orbiter mission' - ardith


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Strategy of meteorological study in Venus Climate Orbiter mission

T. Imamura, M. Nakamura

Institute of Space and Astronautical Sciences


Venus climate orbiter planet c project status and schedule
Venus Climate Orbiter (Planet-C) project: missionStatus and schedule

  • The VCO mission was approved by the Space Development Committee of the government in 2001.

  • Budget request for the prototype model study in 2003 is being made.

  • The spacecraft will be launched in 2008 and arrive at Venus in 2009.

  • The mission life will be more than than 2 earth years.



Earth and venus
Earth and Venus mission

  • They have almost the same size and mass.

  • Surface environments are completely different.

  • How does the climate system depend on planetary parameters?


Thermal structures of Earth and Venus mission

Earth

H2SO4 Cloud

Altitude (km)

Haze

Pressure (atm)

Venus

Temperature (K)



Super rotation of venus atmosphere

Angular momentum flux how they work?

Viscosity?

Super-rotation of Venus’ atmosphere

Although the period of planetary rotation is 243 days, the atmosphere near the cloud top circles around the planet once every 4 days.


Cyclostrophic balance of venus atmosphere
Cyclostrophic balance of Venus’ atmosphere how they work?

Pole

Pole

Strong zonal wind

Cool

Large contrifugal force

Weak zonal wind

Small contrifugal force

Hot

EQ

EQ

These two torques are balanced each other.


Similar wind system in titan s stratosphere
Similar wind system in Titan’s stratosphere? how they work?

Brightness temperature (K)

  • Rotation period= 16 days

  • Assuming cyclostrophic balance, the rotation period of the upper atmosphere is 4 days.

S.Pole EQ N.Pole


A hypothesis for super rotation gierasch s mechanism

how they work?

Direct or indirect cells?

Momentum carrier?

A hypothesis for super-rotation: Gierasch’s mechanism

Hadley celltransports angular momentum upward at low latitudes and downward at high latitudes

Horizontal viscositytransports angular momentum equatorward

Net transport of angular momentum : UPWARD


Meridional circulation how they work?

Shaded: ClockwiseWhite: Anti-clockwise

Venus .. ?

Winter Pole EQ Summer Pole

Earth: 3-cells exist in each hemisphere


Motion of the sun relative to cloud layer how they work?

Acceleration

Tidal wave

Acceleration

Tidal wave

Acceleration

Excitation of eastward-propagating tidal wave accelerates the cloud layer westward.

Acceleration by thermal tide

Cloud layer

Heating region


Model prediction for thermal tide
Model prediction for thermal tide how they work?

Zonal wind

Temperature

Meridional wind

T×√p

Vertical structure of semi-diurnal tide (Takagi, 2001)

Vertical wind

Phase


Goals of the mission
Goals of the mission how they work?

Meteorology

  • Mechanism of super-rotation

  • Structure of meridional circulation

  • Hierarchy of atmospheric motion

  • Lightning

  • Cloud physics

  • Plasma environment

  • Detection of active volcanism

Others


Strategy
STRATEGY how they work?


Requirements for meteorological study
Requirements for meteorological study how they work?

  • Determination of wind field below cloud top

  • Covering both dayside and nightside  Zonally-averaged circulation and momentum flux

  • Multiple altitude levels including sub-cloud region  Vertical structure

  • Covering from meso-scale to planetary-scale  Cross-scale coupling

SOLUTION: Continuoushigh-resolutionglobal imaging from a meteorological satellite (like METEOSAT!)


Near ir windows
Near-IR windows how they work?

Visible-UV

Leakage of thermal emission from the hot lower atmosphere

2.3mm (Galileo flyby)


Altitude regions to be covered how they work?

Angular momentum transport

Zonal wind

Sounding region

(km)

100

80

60

40

20

0

Viscosity?

Airglow (Visible)

Cloud layer

SO /Unknown absorber (UV)

CO absorption (Near-IR)

Cloud top temperature (Long-IR)

2

2

Lower cloud (Near-IR)

Radio occultation

Lightning

CO (Near-IR)

0 50 100

Wind speed (m s-1)


Platform for imaging observation
Platform for imaging observation how they work?

North

Solar cell

500N thruster

MGA

HGA

360 deg

±10 deg

cameras

12 deg FOV, 1000x1000 pixels

South


Synchronization with the super rotation
Synchronization with the super-rotation how they work?

 detect small deviations of atmospheric motion from the background zonal flow

Angle from apoapsis (deg)

Air motion at 50 km altitude

Orbit:

300 km x 13 Venus radii

Inclination 172°

Spacecraft motion

Orbital period = 30 h

Example: Earth cloud movie

Time (hours)


Derivation of wind field how they work?

Continuous global viewing  Cloud motion vectors

100-300 km

Movement with time

Cloud tracked winds on the Earth


Morphology of lower clouds

2.3mm Images byGround-based observation (Crisp et al. 1991)


Instruments
INSTRUMENTS how they work?


Cameras (1) how they work?

  • Near IR camera 1 (IR1)

  • 1.0 mm (near-IR window)

  • 1024 x 1024 pixels, FOV 12deg, SiCCD

  •  Cloud distribution, fine structure of lower cloud (dayside)

  •  Surface emission including active volcanism (nightside)

  • Near IR camera 2 (IR2)

  • 1.7, 2.3, 2.4 mm (near-IR window), 2.0 mm (CO2 absorption)

  • 1040 x 1040 pixels, FOV 12deg, PtSi

  •  Cloud distribution and particle size (nightside)

  •  Cloud top height (dayside, 2.0mm)

  •  Carbon monooxide (nightside)

Galileo (2.3mm)


IR2 thermal test model how they work?

Optics

Filter wheel

Detector housing

Aperture

Stirling cooler

Dayside Nightside

Venus image taken with IR2 test filter (Okayama Astronomical Observatory)


Cameras (2) how they work?

  • UV camera (UVI)

    280, 320 nm

  • 1024 x 1024 pixels, FOV 12deg, SiCCD

  •  SO2 and unknown UV absorber near the cloud top (dayside)

  • Longwave IR camera (LIR)

  • 9-11 mm

  • 240 x 240 pixels, FOV 12deg, Uncooled bolometer

  •  Cloud top temperature (day/night)

  • Lightning and Airglow camera (LAC)

  • 777, 551, 558 nm

  • 8 x 8 pixels, FOV 12deg, Photo diode

  •  High-speed sampling of lightning flashes (nightside)

  •  O2 / O airglows (nightside)

Mariner 10

PVO (North pole)


Operation of cameras
Operation of cameras how they work?

12 deg FOV

  • Whole disk in the field of view over 70% of the orbital period

     Development/decay of planetary-scale features in both hemispheres

     Precise mapping of each pixel onto planetary surface

  • Acquisition every few minutes- few hours (nominal: 2 hours)

  • Spatial resolution is <16 km

  • Near-IR (dayside)

  • Ultraviolet

  • Long-IR

  • Near-IR (nightside)

  • Lightning/Airglow


Radio occultation uso
Radio occultation (USO) how they work?

  • Temperature profiles at two opposite longitudes in the low latitude

  •  Zonal propagation of planetary-scale waves

  • H2SO4 vapor profile

  • Ionosphere

To the earth

Pole

Spacecraft motion

Atmosphere


3 d viewing
3-D viewing how they work?

Dayside

Nightside

Temperature, H2SO4 vapor (Radio occultation)

Airglow (Visible)

90 km

SO2, Unknown absorber (UV)

Cloud top temperature(Mid-IR)

Cloud top height (Near-IR)

70 km

Lower clouds (Near-IR)

50 km

CO (Near-IR)

35-50 km

Cloud motion vectors

0 km

Lightning (Visible)

Surface (Near-IR)


Optical sounding of ground surface how they work?

  • Search for hot lava erupted from active volcano by taking global pictures at 1.0mm every half a day

  • Emissivity distribution of the ground surface


Summary
Summary how they work?

  • The spacecraft will be launched in 2008, arrive at Venus in 2009, and observe meteorological processes more than 2 years.

  • The mission is optimized for observing atmospheric dynamics in the low/mid-latitudes.

  • Science payloads will be multi-wavelength cameras covering wavelengths from UV to IR, USO, plasma detectors, and magnetometer.

  • Collaboration with complementary VEX measurements is strongly needed.


Vex and vco
VEX and VCO how they work?

  • Optimization: Spectroscopy  Imaging

  • Orbit: Polar  Equatorial

  • Global images: High latitudes  Low latitudes


Possible collaboration
Possible collaboration how they work?

  • Complementary information on the general circulation and cloud chemistry


Chemical species related with cloud formation (VEX) how they work?

Spatial correlation between cloud top height and UV contrast (VCO)

  • Origin of ultraviolet contrast

    • Cloud height or UV absorber

    • Mechanism of producing inhomogeneity


Possible collaboration1
Possible collaboration how they work?

  • Complementary information on the general circulation and cloud chemistry

  • Cloud morphology in both low and high latitudes

  • To constrain the VCO sounding region using the VEX spectroscopic data

  • Collaboration in receiving downlink (Radio science)

  • Mutual comparison of the tools for data analysis

    • Radiative transfer code

    • Cloud tracking algorithm

    • General circulation model

  • European instruments onboard VCO


Model predictions for “horizontal viscosity” how they work?

Two-dimensional turbulence in Venus-like mechanical model (Iga, 2001)

Phase velocity-latitude cross section of meridional momentum flux u’v’ in Venus-like GCM (Yamamoto and Takahashi, 2003)


Energy cycle of earth climate system

Venus? how they work?

Energy cycle of Earth climate system

Disturbance potential energy

15.6x105 J/m2

Axi-symmetric potential energy

33.5x105 J/m2

1.5 W/m2

Solar energy

0.7 W/m2

Solar energy

1.5 W/m2

2.2 W/m2

0.2 W/m2

Dissipation

1.9 W/m2

Dissipation

0.1 W/m2

Disturbance kinetic energy

8.8x105 J/m2

Axi-symmetric kinetic energy

3.6x105 J/m2

0.3 W/m2


Planetary waves driving the circulation how they work?

Equatorial waves

Meridional transport of trace gases

Meridional transport of trace gases

VEX VCO

Forbes (2002)

Gravity waves at low latitude (radio occult.)

Gravity waves at high latitude (radio occult.)

Polar collar Polar dipole

H2SO4 vapor at high latitude by radio occult.

H2SO4 vapor at low latitude by radio occult.

Meridional drift velocity at low latitude

Meridional drift velocity at high latitude


ad