1. sun- (/sky-) photometer ground-networks
GAW - aod
AERONET
… complementing LIDAR
SKYnet
MAN - aod
Stefan Kinne
MPI-Met, Hamburg

2. 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
applications
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.
limitation
local nature of sample
day-time nature of sample
abso. less acc at low AOD

3. outline
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

4. AERONET
Laengeren
9/20/2010 data !
 successful recent data access

5. Skynet successful recent data access associations are offered !
here for Hedo
April 2010
September 2010
data on the web !
successful recent
data access

6. GAW - AOD no data access on the nice Swiss web-site
(C.Wehrli)
error message on the NILU/EBAS site

7. MAN - AOD

8. 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

9. 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)

14. sun-photo & modeling = climatology
annual maps of an aerosol climatology

15. evaluating assimilations
2003 AOD AOD
2003 Angstr Angstr
Angstr diff. to AERONET
AOD diff. to AERONET

16. 2004 AOD … is this good ? AOD diff. to AERONET
 underestimate overestimate 

17. scoring AOD performance
score BIAS-sign
(error = 0.44) positive negative temp correlation
error
strength spatial correlat.
bias strength
increasing error 

18. 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

19. extra slides

20. AERONET