meidex – mediterranean israeli dust experiment - a space, air and ground based study of desert...
TRANSCRIPT
MEIDEX – MEDITERRANEAN ISRAELI DUST EXPERIMENT - A SPACE, AIR AND GROUND
BASED STUDY OF DESERT AEROSOLZ. Levin, J. Joseph, Y. Mekler, P. Israelevich, E. Ganor, Y. Yair, A. Devir,
E. Klodzh, I. Koren, M. Mualem, Y. Noter, D. Shtivelman, A. TellerDepartment of Geophysics and Planetary Sciences, Tel Aviv University, Ramat Aviv, Israel
• First Israeli astronaut flight
• Under an agreement between NASA and ISA (Israeli Space Agency)
• An experiment on board the shuttle within the Hitchhiker program
WHY STUDY DUST STORMS?• Desert dust particles are a major component of natural aerosols in the atmosphere
• They may help to cool or warm the atmosphere depending on their distribution, size and chemical composition
• They affect clouds and precipitation
• They are in the right particle size to affect our health being deposited in the lungs
•They affect mechanical systems (e.g. jet engines, helicopters etc.)
• They reduce the contrast in remote sensing measurements
• They affect biological activity in the Ocean
Dust storm over the Dead Sea
Desert dust particles
Desert dust in Tel Aviv (3 pm)
Distribution of Non-absorbing aerosols
MEIDEX SCIENTIFIC OBJECTIVES
DAYTIME PRIMARY EXPERIMENTS:• Validate TOMS versus MODIS• Sources, Transport, Sinks and Properties of Desert Aerosol over the Mediterranean and Atlantic Ocean• Absolute calibration of TOMS and MODIS by ground and airborne measurements
DAYTIME SECONDARY EXPERIMENTS:• Spectral Sea Surface BRDF with emphasis on UV • Construct Visual Slant Visibility Model
NIGHT TIME EXPERIMENT (TERTIARY):• Sprites, Elves and other related phenomena – correlation with ground measurements of electro-magnetic radiation and visual observations.
The regions of interest
General scheme of the experiment
1. Wing mounted optical spectrometers (0.1 to 3 m, and 0.3 to 47 m)
2. Isokinetic sampling of aerosol particles on filters and on electron microscope grids
3. Ram collection of large (>2.5 m) aerosols
4. Two albedometers5. GPS6. Temperature sensors
Airborne Measurements
Flight base: Crete, or Sardinia, or TenerifeRadius: 500 miles
Observations of Sprites
• Sprite observation by XYBION camera will be carried our over South America and the Tropics)
• Simultaneous ground observations will be carried out by teams from a number of countries (Israel, USA, Germany, Brazil, Japan and Taiwan)
• Measurements of VLF waves (in particular Schumann resonance) from TAU Mitzpe Ramon station will be correlated with the space and ground observations
Xybion IMC- 201 radiometric CCD camera
• CCD Sensor: 756Hx581V
• Sensitivity ≥10-6fc (~ 0.1 of typical night sky)
• Spectral range: 340-860nm
• 6 bands: 0.34, 0.38, 0.44, 0.56, 0.66, 0.86 nm
• Exposure Times: 50 nsec - 4 msec in 50 nsec steps
Wide Field Of View - SEKAI White Light video camera
Both cameras are mounted in a 1-axis gimbaled truss
• Gimbal angular range: ± 22.5 Degrees
• Scan direction: ± Y
• FOV Xybion: 16o (68km at the altitude 256km - 100m/pix)
• FOV SEKAI: 60o (270 km at the altitude 256 km)
Dust forecast for daily planning
Dust Forecast with the TAU_ETA model and TOMS observations
for April 23, 2001
The data is transformed into a two-dimensional wavelet space with the cloud cluster and the dust cluster separated and orthogonal.
Chemical analysis and size distribution of dust samples
Chemical spectra of dust particles (<10 m) sampled before, during and after severe dust storm April 14-22, 2000, at Tel Aviv
Spaceborne Measurements
Dust and Clouds Detection
Input image – SeaWiFS – Saharan Dust Storm
28-02-2000
Classification (wavelets) Red - Clouds, Green -
Ocean, Blue - Dust
Original image filtered by the mask
http://www.tau.ac.il/geophysics/MEIDEX/home.htm
Comparison between aerosol volume distributions during and after dust storm, April 21, 2001, at Tel Aviv
Upper End Plate w/ Quartz Window
Gimbal Motor & Worm Drive
Worm Gear
SEKAI WFOV Camera
Lower End Plate
Lens & Baffle
Xybion Camera
Avionics Mount Plate w/ electronics
Overall MEIDEX configuration