1. Cloud Optical & Microphysical Properties (M. D. King, S. Platnick, M
Cloud Optical & Microphysical Properties (M. D. King, S. Platnick, M. Gray, E. Moody, et al. – NASA GSFC, UMBC)
Optical thickness, particle size (effective radius), and water path
1 km spatial resolution, daytime only, liquid water & ice clouds
Solar reflectance technique, VIS through MWIR
Water nonabsorbing bands: 0.65, 0.86, 1.24 µm
Water absorbing bands: 1.6, 2.1, 3.7 µm
Land, ocean, and snow/sea ice surfaces
Land surface: 0.65 µm
Ocean surface: 0.86 µm
Snow/ice surfaces: 1.24 µm
MODIS 1st satellite sensor with all useful SWIR, MWIR bands

2. Liquid Water Clouds - ocean surface
Retrieval of tc and re
The reflection function of a nonabsorbing band (e.g., 0.86 µm) is primarily a function of optical thickness
The reflection function of a near-infrared absorbing band (e.g., 2.14 µm) is primarily a function of effective radius
clouds with small drops (or ice crystals) reflect more than those with large particles
For optically thick clouds, there is a near orthogonality in the retrieval of tc and re using a visible and near-infrared band
Liquid Water Clouds - ocean surface

3. Ice Clouds - ocean surface
Retrieval of tc and re
The reflection function of a nonabsorbing band (e.g., 0.86 µm) is primarily a function of optical thickness
The reflection function of a near-infrared absorbing band (e.g., 2.14 µm) is primarily a function of effective radius
clouds with small drops (or ice crystals) reflect more than those with large particles
For optically thick clouds, there is a near orthogonality in the retrieval of tc and re using a visible and near-infrared band
Ice Clouds - ocean surface

4. Cloud Optical & Microphysical Properties Retrieval Example
Liquid Water Clouds - ocean surface
Liquid Water Clouds - ice surface

5. Cloud Optical & Microphysical Properties
Critical input
Cloud mask
to retrieve or not to retrieve?
Cloud thermodynamic phase
use liquid water or ice libraries?
Surface albedo
for land, ancillary information regarding snow/ice extent (NISE data set)
Atmospheric correction
requires cloud top pressure, ancillary information regarding atmospheric moisture & temperature (e.g., NCEP, DAO, other MODIS products)
3.7 µm emission (band contains both solar and emissive signal)
need cloud top temperature, ancillary for surface temperature (e.g., from NCEP, DAO, ...)

6. MOD12 (IGBP ecosystem classification) + USGS water + tundra
Ecosystem Map (A. H. Strahler, C. B. Schaaf, et al. – Boston University)
MOD12 (IGBP ecosystem classification) + USGS water + tundra
For the time being we’re using ecosystem as a surrogate for surface albedo.

7. Surface Albedo Surface albedo = ecosystem + MOD43 (Strahler, Schaaf et al.) aggregation
For the time being we’re using ecosystem as a surrogate for surface albedo.

8. Ecosystem Color Scheme
Albedo Movies
Loops through bands 0.65, 0.86,
1.24, 1.64, 2.1, and 3.7 µm
Loops through seasonal equinox
and solstice, progressing from
Julian days 91, 173, 293, 356
Ecosystem Color Scheme
Pink = Crops
Green = Trees
Yellows = Barren/Deserts
Blues = Savannas

9. Atmospheric Correction
Cloud library calculations give cloud-top quantities (no atmosphere)
atmosphere included during retrieval
Rayleigh scattering
iterative approach applied to 0.65 µm band only (used over land)
important for thin clouds and for any clouds with large solar/view angle combinations
Atmospheric absorption
Well-mixed gases a function of pc, water vapor absorption a function of profile; both a weak function of temperature
Assume above-cloud column water vapor amount the primary parameter, vapor profile of minor consequence
Library calculations made at a variety of pc, above-cloud column water amounts (scaled from various water vapor and temperature profiles), geometries
using MODTRAN 4.0 with scripts for 2-way transmittance calculations
requires cloud top pressure, and ancillary information regarding atmospheric moisture (currently using NCEP)

10. Two-way Atmospheric Path Transmittance (1/µ + 1/µ0)
pc = 900 hPa
w = 2.0 g-cm-2 above-cloud precipitable water
µ0 = 0.8
0.86, 1.24 µm
1.6 µm
0.67 µm
2.1 µm
3.7 µm
(1-way µ path)
Absorption transmittance
For the time being we’re using ecosystem as a surrogate for surface albedo.
3.7 µm
cosine of viewing zenith angle (µ)

11. Cloud Optical Thickness in the Arctic: Provisional Production Code (edition 3)
June 2, 2001 tc 20 15 10 5

12. Cloud Optical Thickness in the Arctic: Provisional Production Code (new correction)
June 2, 2001 tc 20 15 10 5

13. Cloud Effective Radius in the Arctic: Provisional Production Code (edition 3)
June 2, 2001
re(µm) 40 34 28 22 16 10 4

14. Cloud Effective Radius in the Arctic: Provisional Production Code (new correction)
June 2, 2001
re(µm) 40 34 28 22 16 10 4

15. Level-2 Global Cloud Images
Cloud Top Temperature
Bispectral Phase
Cloud Effective Radius
Cloud Optical Thickness
Cloud Mask
Land Classification
True Color Image
October 1, 2001

16. Drakensberg escarpment
SAFARI 2000 Core Sites
Mongu
Okavango
Delta
Etosha Pan
Maun
Sua Pan
Swakopmund
Tshane
Skukuza
Namib Desert
Inhaca Island
Drakensberg escarpment

17. (red = in-cloud portions)
ER-2, C-130
ground tracks
MODIS true color
11 Sept. 2000, 0940 UTC
ER-2
Validation
region
C-130
(red = in-cloud portions)

18. UK C-130 in situ droplet radius, liquid water content
11 Sept. 2000, UTC (S. Osborne, Met Office)
optical thickness: C-130 ≈ 5, MODIS ≈ 3±1
MODIS droplet size retrievals

19. Previous + SAFARI 2000 Namibian Sc studies
California central valley fog
AVHRR
California Sc
MAS
Arctic stratus
(Jan. & April 1989, 2 AM scenes, )
Namibian Sc
AVHRR
(Sep. 1999, 3 PM scenes)
(Oct. 1995, SATE-2 validation)
ATSR-2
MODIS
18 Sept.
11 Sept.
7 Sept.
2 Sept.
C-130
13 Sept.
CV-580 5 10 15 20 25
cloud droplet effective radius (µm)
Namibian Sc often have significantly smaller droplet sizes than other regimes? Or lack the larger droplet sizes of other regimes? A difference in CCN concentrations? If so, why?

20. Retrieved Optical Thickness
Comparison of Visible Optical Thickness (G. G. Mace, S. Bensen, K. Sassen – University of Utah)
Retrieved Optical Thickness
MOD06 Optical Thickness

21. Gridded Level-3 Joint Atmosphere Products (M. D. King, S. Platnick, P
Gridded Level-3 Joint Atmosphere Products (M. D. King, S. Platnick, P. A. Hubanks, et al. – NASA GSFC, UMBC)
Daily, 8-day, and monthly products (474.8, 883.2, MB)
1° ´1° equal angle grid
Mean, standard deviation, marginal probability density function, joint probability density functions

22. Cloud Optical Thickness
Level-3 Monthly
April 2001 tc 20 16 12 8 4

23. Cloud Effective Particle Radius
Level-3 Monthly
April 2001
re(µm) 40 34 28 22 16 10 4

24. L3 product bin sizes (liquid water clouds)
MODIS L3 aggregation from 6°x 6° grid off Namibian coast liquid water clouds
L3 product bin sizes (liquid water clouds)

25. Cloud Top Pressure (W. P. Menzel, R. Frey, K. Strabala, L
Cloud Top Pressure (W. P. Menzel, R. Frey, K. Strabala, L. Gumley, et al. – NOAA NESDIS, U. Wisconsin/CIMSS)
Level-3 Monthly
April 2001
pc (hPa)
1000
900
800
700
600
500
400
300

26. Precipitable Water over Land & Sunglint (B. C. Gao, et al
Precipitable Water over Land & Sunglint (B. C. Gao, et al. – Naval Research Laboratory)
Level-3 Monthly
April 2001
q (cm)
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0

27. MODIS Aerosol Optical Thickness & Effective Radius
ta (0.55 µm) re
0.5
2.4
0.4
1.8
0.3
1.2
0.2
0.6
0.1
0.0
0.0

28. Aerosol Optical Thickness (fine mode) (Y. J. Kaufman, D. Tanré, L. A
Aerosol Optical Thickness (fine mode) (Y. J. Kaufman, D. Tanré, L. A. Remer, D. A. Chu. – NASA GSFC, CNES/USTL)
Level-3 Monthly
September 2000
ta (0.55 µm)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

29. Aerosol Optical Thickness (coarse mode) (Y. J. Kaufman, D. Tanré, L. A
Aerosol Optical Thickness (coarse mode) (Y. J. Kaufman, D. Tanré, L. A. Remer, D. A. Chu. – NASA GSFC, CNES/USTL)
Level-3 Monthly
September 2000
ta (0.55 µm)
0.4
0.3
0.2
0.1
0.0