EARLINET and Satellites:
Partners for Aerosol Observations
Matthias Wiegner
Universität München
Meteorologisches Institut
(Satellites: spaceborne passive radiometry)
Radiative transfer equation
RTE
Radiative transfer equation
radiance (upward)
Radiative transfer equation
source function
Radiative transfer equation
optical depth (=0 at top at atmosphere)
zenith and azimuth angle of radiance
Radiative transfer equation
source function
Source Fkt.
Radiative transfer equation
source function
Single scattering albedo
Radiative transfer equation
source function
phase function
Radiative transfer equation
RTE
Radiative transfer equation
Solution
Solution
Radiative transfer equation
Solution
contribution from atmosphere
Radiative transfer equation
Solution
contribution from surface
Radiance at satellite depends on
phase function, single scattering albedo
air molecules, aerosol particles, cloud droplets
size, refractive index, shape; height dependent
and surface properties
as the vertical coordinate is the optical depth,
radiance also depends on the extinction coefficient
Radiance Dependences
Radiance and aerosols: link
optical and microphysical
parameters of aerosols
other atmospheric and
surface parameters
radiances at satellite sensor
Radiance and aerosols: link
optical and microphysical
parameters of aerosols
other atmospheric and
surface parameters
retrieval algorithms
radiances at satellite sensor
EARLINET- satellite partnership
optical and microphysical
parameters of aerosols
other atmospheric and
surface parameters
retrieval algorithms
calibrated, validated, complemented
radiances at satellite sensor
partnership
This was the introduction
Main topic of my talk
How can we establish an
„EARLINET-Satellite partnership“?
Possible EARLINET contributions
Ground truthing
Calibration and validation of
satellite data and retrieval algorithms
Supply of complementary information
Consequence:
Definition of the small workpackage „WP8“
Possible contrib. overview
Possible EARLINET contributions
Ground truthing
Calibration and validation of
satellite data and retrieval algorithms
Supply of complementary information
Consequence:
Definition of the small workpackage „WP8“
Ground truth (cal/val)
Use the EARLINET data-base
„point by point“ intercomparisons
(lidar measurements during an overpass)
averaged data (e.g., monthly means)
Examples of partnership
Validation and calibration of MIPAS
Focus on ozone (balloon)
No aerosols intercomparions yet
Status: waiting for overpasses
Vincenzo Rizi et al., L'Aquila
Example (1)
Examples of partnership
Validation and calibration of MIPAS + GOMOS
Focus on water vapour and aerosols
Few overpasses, but no aerosol data
Status: ongoing (waiting)
Gelsomina Pappalardo et al., Potenza
Examples of partnership
Validation and calibration of SAGE
Focus on stratospheric aerosols
Regular measurements began in summer 02
Status: ongoing, no final results
Thomas Trickl et al., Garmisch-Partenkirchen
Examples of partnership
Validation and calibration of CHRIS
Focus on land surfaces
Four intensive field experiments scheduled
near Gilching
Project for On-Board Autonomy Small Satellite Mission
Compact High Resolution Imaging Spectrometer
MIM in co-operation with:
Examples of partnership
Goal
Full characterization of surface and atmosphere of exactly
the same scene
Requirements
co-incidence, co-location, very small satellite pixel
Acquisition mode
CHRIS: 18 km swath, 25 m resolution, 19 spectral
bands (0.4-1.05 µm), along track (5 angles)
Time and place
May to August 2002 in Gilching
Examples of partnership
Results/Conclusions
Satellite PROBA encountered severe problems:
no data were available in summer 2002.
A new intensive field experiment is uncertain
MIM & GTCO
Possible EARLINET contributions
Ground truthing
Calibration and Validation of
satellite data and retrieval algorithms
Supply of complementary information
Consequence:
Definition of the small workpackage „WP8“
Relevant (aerosol) parameters
Aerosol optical depth/extinction coefficient
Aerosol type
Aerosol (vertical) distribution
Surface albedo
Solar zenith angle
Fixed wavelength (532 nm)
Relevant Aerosol Parameters
Model calculations
Vertical
aerosol distribution:
5 cases
(1) (2) (3) (4) (5)
A-Profiles
Change of Radiance
as a function of
aerosol optical depth
for different
aerosol profiles
fixed aerosol type
Difference of isotropic radiance
at TOA, rel. to „no aerosol“-case
Sensitivity profiles
Change of Radiance
different aerosol type
Change of Radiance
different aerosol type
Change of Radiance
different aerosol type
Change of Radiance
different aerosol type
Change of Radiance
as a function of
aerosol optical depth
for different 2-layer
aerosol profiles
fixed aerosol type
2-layer profiles
Change of Radiance
different aerosol type
Change of Radiance
different aerosol type
Change of Radiance
different aerosol type
Change of Radiance
different aerosol type
Change of Radiance
different layer width
Conclusions from simulations
Satellite radiances are significantly influenced
by aerosols:
-- optical depth
-- aerosol type
-- aerosol profile
Conclusions Simul.
Examples of partnership
Aerosol vertical distribution is hardly retrievable
from satellites
EARLINET can provide this missing information
Vertical aerosol distribution is relevant for
local energy budget, hydrological cycle,
validation of CTM, ecology,....
...and satellite validation as well
TOMS 10.10.01
TOMS 16.10.01
Benefit of partnership
Results/Conclusions
Aerosol profiles from more than 20 lidar stations, two
times a week and for three years are available. Data
and instruments have undergone QA.
Validation of aerosol retrievals requires a careful selection
of time and place, and averaging over reasonable periods.
First co-operations are initiated.
EARLINET can provide aerosol data that cannot be
obtained from passive radiometry.
Benefit: Results
Benefit of partnership
The (bright) future
Envisat and MSG are still at the beginning of their operation.
Data archive of EARLINET is available
Spaceborne lidar is (almost) ready to launch
Most of the EARLINET-systems stay operational
Co-operation requires extra funding !!!!
Benefit: Actions