EARLINET and Satellites: Partners for Aerosol Observations

Matthias WiegnerUniversität München

Meteorologisches Institut

(Satellites: spaceborne passive radiometry)

Radiative transfer equation

RTE

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

Radiative transfer equation

Source Fkt.

Single scattering albedo

Radiative transfer equation

source function

phase function

Radiative transfer equation

source function

Radiative transfer equation

RTE

Solution

Radiative transfer equation

Solution

contribution from atmosphere

Radiative transfer equation

Solution

contribution from surface

Radiative transfer equation

Solution

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

Verticalaerosol distribution:

5 cases

(1) (2) (3) (4) (5)

A-Profiles

Model calculations

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

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 ofaerosol optical depthfor different 2-layeraerosol 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

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

TOMS 10.10.01

TOMS 16.10.01

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.

The (bright) future

Envisat and MSG are still at the beginning of their operation.

Benefit of partnership

Co-operation requires extra funding !!!!

Benefit: Actions

Most of the EARLINET-systems stay operational

Data archive of EARLINET is available

Spaceborne lidar is (almost) ready to launch