sun sky photometer ground networks n.
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sun- (/sky-) photometer ground-networks. GAW - aod. AERONET. … complementing LIDAR. Stefan Kinne MPI-Met, Hamburg. SKYnet. MAN - aod. can do aerosol column properties AOD at several wavel. fine mode AOD fraction water vapor size distribution (sky) absorption AOD (sky)

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sun- (/sky-) photometer ground-networks

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sun sky photometer ground networks

sun- (/sky-) photometerground-networks

GAW - aod


… complementing LIDAR

Stefan Kinne

MPI-Met, Hamburg


MAN - aod

sun sky photometers
can do

aerosol column properties

AOD at several wavel.

fine mode AOD fraction

water vapor

size distribution (sky)

absorption AOD (sky)

cloud opt.depth (sky)

consistency through calibr. networks operation

cannot do

night time (need the sun)

when clouds are present

vertical stratification


calibration and reference for lidar remote sensing

reference in evaluations of aerosol global modeling

complementary nature to lidar (at MPL-NET and most EARLINET sites)

AOD = integrated ext.


local nature of sample

day-time nature of sample

abso. less acc at low AOD

sun- (/sky-) photometers
  • what major sun-photometer networks exist and are recent data accessible ?
  • why are aerosol properties of sun-photometry more accurate than satellite retrievals?
  • data-samples in the global context
  • application sample in aerosol assimilations
  • why lidar-sites should upgrade to sun-photometers (and radiometers and cloud- and precipitation radars)  complementary nature


 successful recent data access

9/20/2010 data !



are offered !

here for Hedo

April 2010

September 2010

data on the web !

successful recent

data access

gaw aod

no data access on the nice Swiss web-site (C.Wehrli)

error message on the NILU/EBAS site

sun photo vs sat retrieval
AOD data based on solar radiation attenuation data … function of

trace-gas absorption

molecular scattering

amount matters

sky-radiance data of additional info on

size-distribution (.1-10um)

absorption if AOD is large (suff. signal / noise ratio)

AOD based on reflected radiances … function of

trace-gas absorption

molecular scattering

amount matters

size matters (pre-selected)

shape matters (spheres)

absorption mat. (assumed)

surface properties need to be known:

D 1% alb ~ D 0.1 AOD

sun-photo vs. sat-retrieval
global data applications
global … data / applications
  • seasonal multi-annual averages for
    • ‘amount’ AOD (aerosol optical depth)
    • ‘size’ Angstrom / fine-mode fraction
    • ‘absorption’ absorption-AOD (= AOD * (1-ssa))
    • ‘water-vapor’
  • combining with modeling  climatology which is superior to modeling
  • evaluation (of assimilations)
sun photo modeling climatology
sun-photo & modeling = climatology

annual maps of an aerosol climatology

evaluating assimilations
2003 AOD 2004 AOD

2003 Angstr 2004 Angstr

evaluating assimilations

Angstr diff. to AERONET

AOD diff. to AERONET

2004 aod is this good
2004 AOD … is this good ?

AOD diff. to AERONET

 underestimate overestimate 

scoring aod performance
scoring AOD performance

score - 0.56 BIAS-sign

(error = 0.44) positivenegative temp correlation


strength spatial correlat.


bias strength


increasing error 

complementary nature
complementary nature

even though lidar and sun-/sky-photometer have different viewing geometries …

  • lidar needs (or can use)
    • the complementary constraint on column integrated extinction (=AOD) and other column aero properties
    • the more continuous temporal day-time coverage
  • sun-/sky photometry are extended by lidar
    • via vertical stratification of properties
    • via night-time coverage