CalWater-2, MISR, and AirMSPI
CalWater 2015 Planning Workship
La Jolla, CA
23 April 2014
D.J. Diner, M.G. Tosca, M.J. Garay, O.V. Kalashnikova, and F. Xu
Jet Propulsion Laboratory, California Institute of Technology
© 2014 California Institute of Technology. Government sponsorship acknowledged.
Multi-angle Imaging
SpectroRadiometer
(MISR)
Airborne Multiangle
SpectroPolarimetric
Imager (AirMSPI)
446, 558, 672, 866 nm
355, 380, 445, 470*,555, 660*,
865*, 935 nm (*polarimetric)
Flying on Terra since 1999
705 km flight altitude
Multiangle viewing between ±70º
Spatial resolution: 275 m
Flying on NASA ER-2 since
2010
20 km flight altitude
Multiangle viewing between ±67º
1
Spatial resolution: 10 m
Dust source characterization - 1
Transport models such
as NAAPS predict dust
trajectories, but need
reliable source
locations and emission
strengths
Plume height
3 km
2 km
1 km
0 km
ASIA: MISR 9-angle animation and stereo retrieval of dust
plume height in Gobi Desert, 30 March 2007
MIDDLE EAST: Increasing
prevalence of sandstorms
2
Dust source characterization - 2
AFRICA
0.02
0.2
0.4
0.6
0.8
1.0 0.01
Aerosol Optical
Depth (558 nm)
AOD retrieval over bright
land areas
0.12
0.24
0.36
0.48
Nonspherical Aerosol
Optical Depth Fraction
Particle shape
discrimination
0.60 0.1
0.6
1.3
1.9
2.6
>3.2
Frequency of Wind Speeds
Greater Than 20 m/s
Cloud- and plume-tracked
wind retrievals
MISR CAPABILITY
3
MISR aerosol observations over CA Central Valley
Aerosol
Optical Depth
(AOD)
Map of Central California from 20 January 2013 showing MISR retrievals of
AOD at 4.4 km resolution. Diamonds are ground-based AERONET DRAGON
sites colored by AOD. Regression plot is also shown.
4
Example AirMSPI aerosol retrieval during SEAC4RS
Southern Arkansas,
23 Aug 2013, 1617 UTC
Elevated, transported
smoke present in scene
29.1º view zenith angle
Radiance 445, 555, 660 nm
Degree of linear polarization 470, 660, 865 nm
Spatially Averaged
4STAR (30 min average) vs. AirMSPI (spatial average) AOD
0.998
0.6
4STAR AOD
AirMSPI AOD
scattering
Single
albedo
Single Scattering
Albedo
(Imag)
depth
Aerosol optical
AOD
0.5
4STAR sunphotometer on
DC-8: Mean and stdev
over 30 min window
0.4
0.3
0.2
0.1
0
200
AirMSPI: Spatial
mean and stdev Aerosol
over entire scene retrievals run
at JPL using
Univ. of Lille
GRASP
code,
courtesy O.
Dubovik
0.996
0.994
0.992
0.99
0.988
0.986
400
600
800
1000
Wavelength
1200
Wavelength (nm)
1400
1600
0.984
300
400
500
600
700
Wavelegnth (nm)
Wavelength (nm)
800
900
5
Polarimetric sensitivity to aerosol particle size
Monomodal aerosol model
Median particle radius 0.06 mm
Both models are consistent with
MISR radiance-only data. AirMSPI
polarimetry distinguishes them
model
observations
Bimodal aerosol model
40% fine mode, median particle
radius = 0.03 mm
60% coarse mode, median
particle radius = 1.00 mm
Aerosol bow due to
larger particles in
model—not seen in
degree of linear
polarization (DOLP
MISR image off the
California coast,
19 July 2012
6
AR cloud height and wind retrievals from MISR
m/s
21 Dec 2010
mid-level
clouds
SSMI Water Vapor Imagery
(yellows, reds = high vapor content)
MISR heightresolved wind
vectors show
details of the flow
within landfalling
atmospheric rivers
low
clouds
high
clouds
height (m)
7
Cloud height and wind retrievals from AirMSPI
AirMSPI flight transects
across atmospheric rivers will
allow simultaneous retrieval
of cloud height and wind
speed at high spatial
resolution (~100 m)
As with MISR, stereo
retrievals are purely
geometric  no dependence
on atmospheric temperature
profile  accurate height
assignments of winds
26.5º forward: 19:44 UTC
Nadir: 19:45 UTC
26.5º backward: 19:46 UTC
8
AirMSPI cloud-top drop size retrieval over warm clouds
glory
primary
cloudbow
supernumerary
bows
6 August 2013
1859 UTC
The cloudbow,
glory, and
supernumerary
bows indicate
spherical drops
0.80
0.60
Offset peaks cause colored fringes
0.40
P12
0.20
An effective droplet radius of 12 mm fits
the data well
0.00
-0.20
-0.40
470 nm data
660 nm data (+0.3)
865 nm data (+0.6)
-0.60
470 nm model
660 nm model (+0.3)
865 nm model (+0.6)
-0.80
135
140
145
150
155
Scattering angle (deg)
160
165
170
9
Identification of ice clouds in polarized light from AirMSPI
scattering angle of subsun
1 February 2013
2111 UTC
Absence of glory or cloudbows indicates
nonspherical particles. Subsun implies
horizontally-oriented ice crystal plates.
Polarized radiance vs. scattering angle
 optical depth and crystal habit
(Chepfer et al., 1998; van Diedenhoven
et al., 2012, Cole et al., 2013)
Cloud Physics Lidar (CPL) data show a
high-altitude cloud layer above lower cloud
credit: J. Yorks, W. Hart
10
Conclusions
MISR multiangle radiance and AirMSPI multiangle radiance/polarization
observations provide contextual aerosol and cloud microphysics,
height, and wind data to complement other CalWater measurements
• These data provide environmental constraints on factors
governing precipitation rates
• The combination of MISR, AirMSPI, and CALIPSO could be
used to improve optical models of transported Pacific dust
A second-generation instrument, AirMSPI-2, is being readied for initial
flights in fall 2014. AirMSPI-2 adds O2 A-band and shortwave infrared
(SWIR) channels
• Multiangle O2 A-band observations are sensitive to cloud
geometric thickness
• SWIR channels enable MODIS-like joint retrievals of cloud
optical depth and particle size
11