EARLINET and Satellites: Partners for Aerosol Observations
Matthias WiegnerUniversität München
Meteorologisches Institut
(Satellites: spaceborne passive radiometry)
optical depth (=0 at top at atmosphere)
zenith and azimuth angle of radiance
Radiative transfer equation
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 at satellite depends on
Radiance Dependences
optical and microphysical parameters of aerosols
radiances at satellite sensor
other atmospheric andsurface parameters
Radiance and aerosols: link
Link
optical and microphysical parameters of aerosols
radiances at satellite sensor
other atmospheric andsurface parameters
retrieval algorithms
Radiance and aerosols: link
optical and microphysical parameters of aerosols
radiances at satellite sensor
other atmospheric andsurface parameters
EARLINET- satellite partnership
retrieval algorithms
calibrated, validated, supplemented
partnership
This was the introduction
Main topic of my talk
How can we establish an „EARLINET-Satellite partnership“?
Intro Ende
Calibration and validation of satellite data and retrieval algorithms
Supply of complementary information
Ground truthing
Consequence: Definition of the small workpackage „WP8“
Possible EARLINET contributions
Possible contrib. overview
Calibration and validation of satellite data and retrieval algorithms
Supply of complementary information
Ground truthing
Consequence: Definition of the small workpackage „WP8“
Possible EARLINET contributions
Use the EARLINET data-base
averaged data (e.g., monthly means)
„point by point“ intercomparisons (lidar measurements during an overpass)
Ground truth (cal/val)
Validation and calibration of MIPAS
Focus on ozone (balloon)No aerosols intercomparions yet
Status: waiting for overpasses
Examples of partnership
Vincenzo Rizi et al., L'Aquila
Example (1)
Validation and calibration of SAGE
Focus on stratospheric aerosolsRegular measurements began in summer 02
Status: ongoing, no final results
Examples of partnership
Thomas Trickl et al., Garmisch-Partenkirchen
Validation and calibration of MIPAS + GOMOS
Focus on water vapour and aerosolsFew overpasses, but no aerosol data
Status: ongoing (waiting)
Examples of partnership
Gelsomina Pappalardo et al., Potenza
Examples of partnership
MIM in co-operation with:
Project for On-Board Autonomy Small Satellite MissionCompact High Resolution Imaging Spectrometer
GTCO
Validation and calibration of CHRIS
Focus on land surfaces
Four intensive field experiments schedulednear Gilching
Acquisition modeCHRIS: 18 km swath, 25 m resolution, 19 spectral bands (0.4-1.05 µm), along track (5 angles)
Time and placeMay to August 2002 in Gilching
GoalFull characterization of surface and atmosphere of exactlythe same scene
Requirementsco-incidence, co-location, very small satellite pixel
Examples of partnership
Results/Conclusions
Satellite PROBA encountered severe problems: no data were available in summer 2002.
A new intensive field experiment is uncertain
Examples of partnership
MIM & GTCO
Calibration and Validation of satellite data and retrieval algorithms
Supply of complementary information
Ground truthing
Consequence: Definition of the small workpackage „WP8“
Possible EARLINET contributions
Supplementary Data
Aerosol optical depth
Aerosol type
Aerosol (vertical) distribution
Surface albedo
Solar zenith angle
Fixed wavelength (532 nm)
Relevant Aerosol Parameters
Relevant (aerosol) parameters
as a function ofaerosol optical depthfor different aerosol profiles
fixed aerosol type
Change of Radiance
Difference of isotropic radianceat TOA, rel. to „no aerosol“-case
Sensitivity profiles
Change of Radiance
as a function ofaerosol optical depthfor different 2-layeraerosol profiles
fixed aerosol type
2-layer profiles
Satellite radiances are significantly influenced by aerosols:
-- optical depth-- aerosol type-- aerosol profile
Conclusions Simul.
Conclusions from simulations
Aerosol vertical distribution is hardly retrievablefrom satellites
Examples of partnership
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
Results/Conclusions
Aerosol profiles from more than 20 lidar stations, twotimes a week and for three years are available. Dataand instruments have undergone QA.
Benefit of partnership
Benefit: Results
EARLINET can provide aerosol data that cannot beobtained from passive radiometry.
Validation of aerosol retrievals requires a careful selectionof time and place, and averaging over reasonable periods.First co-operations are initiated.