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