Happy New Year!
AERONET with the collaboration
of PHOTONS and many other partners has grown rapidly in geographic
distribution and importance to the scientific community due to improved
data access to more and better product types during the last five
years. Our web tracking statistics showed there were
26,740 unique visitors to the AERONET website last year. Congratulations to everyone for making the federated
network such a valuable resource for the research community and the
planet. This Quarterly reviews
the following headlines:
AERONET/PHOTONS workshop planned for
May 10-14, 2004 in Spain
New instrument models are functioning well
Inversion Corner Review and Update
New Inversion release anticipated in
New AOT Version to be released
Tracking status of instruments,
the new relational data base
Calibration-The network has
two official calibration sites
Publications and Research
I feel that to keep the
network innovative and relevant that we need a two-way communication
between the AERONET and PHOTONS staff and our research and operational
community. I’d like to announce an AERONET/PHOTONS workshop
to be held in El Arenesillo,
Spain from May
10 to May 14, 2004. The workshop will be hosted by the University
and INRA through the capable efforts of Drs. Angel de Frutos
and Victoria Cachorro. Sessions will be run by AERONET and PHOTONS
staff but will only be useful with the active participation of the
attendees. Our experience has
shown that data quality and quantity is driven by integrating research
needs with operational understanding thus this workshop is unique
in that we want all aspects of the program represented during the
course of the week.
- Day 1: a program overview AERONET/PHOTONS staff
- Days two and three:
Research issues, invited and solicited talks and poster session.
- Days 4 and 5: Operational
issues such as instrument maintenance, AERONET webpage surfing,
data products, database management, etc. I want to particularly emphasize the importance
for site managers to attend.
- I invite you to submit an abstract for a science talk
(which we’re emphasizing integrated aerosol research that may or
may not involve AERONET data) or a poster session that will emphasize
AERONET/PHOTONS activities. If
you are interested in providing a talk or poster please send a short
abstract to Amy Scully.
- If you want to attend, please also let Amy know as soon
as you can so we can get a head count.
- Please see the AERONET homepage (http://aeronet.gsfc.nasa.gov) for
more details including the agenda and logistics.
More Current matters:
Weather/calibration: Despite having nearly 2 meters of rain equivalent
this past year at Goddard we managed to catch up on our intercomparison/calibration backlog this fall. We currently have 39 instruments in the calibration/maintenance
queue at Goddard and 15 at the PHOTONS facilities. More tend to come in during this season due
to darkness and poor weather at the higher northern latitudes.
New instrument models are functioning well:
The new model instruments
featuring the 1.64 mm channels
are operating well however a few minor issues persist including rare
periodic negative spikes (~1/day) in the AOD that are screened by
the cloud screening algorithm. Not all corrections are applied to
this channel thus it cannot be raised to level 2 status as yet (see
New version section). The tracking, symmetry about the aureole, stray
light rejection and dynamic range all appear to be as good
or better than the old instruments.
We had anticipated two 1020 nm AOD retrievals (Si
detector and InGAS
detector) however the InGAS is significantly
more noisy so it is not displayed nor downloadable on the website. The new version polarization instrument appears
to function as expected.
model is accepted into the network for assessing atmospheric parameters
as well as estimating ocean leaving radiances (Zibordi
et al., 2004, submitted to IEEE Trans.).
This instrument makes selected ocean radiance observations. We currently provide the radiance observations
but the ocean leaving radiance products are planned for mid-year.
Cimel does provide upgrades
of old instruments that that AERONET and PHOTONS staff will install
if the instrument owner chooses to purchase the kit.
Please contact Cimel for details.
Considering the condition of some instruments particularly
those located near marine aerosols, I feel this is should be considered.
Inversion Corner-Review and Update:
are operationally computed using the 1996 Nakajima Code, the Dubovik spherical model and the new Dubovik
spheroid model for almucantars. PP
inversions are currently being processed for the Dubovik
spherical and spheroid models but the current analysis shows them
to be less stable than almucantars.
Currently only the Nakajima and Dubovik
spherical and spheroid models (almucantars
only) are available from the AERONET download tool.
1: Does not apply to Inversions.
1.5: Inversions produced from predeployment
calibrations using cloud screened AOT data.
Level 1.5 inversions will be post field calibrated if the instruments
have been returned for post field calibration.
2 inversion products: The data have been post field calibrated
and cloud screened, inversion screening criteria are applied to raise
selected data to ‘Quality Assured’ status.
Note: QA criteria for Level 2 was subsequently ‘slightly
modified’ in September 03 to more adequately screen for unrealistic
endpoints of the size distribution.
Database is being upgraded again to accommodate the increased number
of products from the various processing models and in anticipation
of new processing strategies. Our best chronological guess for
availability through the AERONET website follows:
& spheroid 4 almucantars (Level 1.5
& spheroid 4 PP (Level 1.5)-processed but not operationally available
Dubovik spherical & spheroid 6 almucantar–Proposed
& spheroid , 6 PP (Level 1.5)- processed
for April but not operationally available
Polarization from PP @ 870 nm (Level 1)-Current (No QA strategy
New Inversion release anticipated in
A new more computationally
efficient inversion is currently being tested that will facilitate
processing of variable spectral inversions from almucantars,
PP, polarization and combination of such measurements. This also has enhancements to the PP inversion
module. Implementation of
this will require reprocessing of the entire data base likely in April
this year. Current product
types will be maintained with the exception of the Nakajima retrievals. This new database will be designated as ‘Version
2I’(I=inversion) to replace the current ‘Version
New AOT Version to be released:
Over the years small improvements
to the various AOT algorithms have been published and accepted by
the community. We plan to release
‘Version 2A’ (A=AOT) in March that will include the latest enhancements. At that time the entire data base will have
been reprocessed. The improvements
Vapor retrievals (Hitran database and line
by line radiative transfer mthd)
nm water vapor correction
nm water vapor, CO2 and CH4 corrections
Air pressure measurements from web and or modeled sources for
Rayleigh correction where appropriate
Rayleigh algorithm upgrade
LUT correction based on TOMS monthly climatology (1 deg X 1 deg)
and coarse fractions based on O’Neil (2003)
Tracking status of instruments,
the new relational data base:
many parameters of an instrument and it’s location, including maintenance,
filters, calibration status and coefficients, site manager coordinates
and photos, site location etc in web-based
‘FileMaker’ a relational data base that has proven extremely
useful for asking questions like: What field instruments are due for
calibration? The answer is immediate and has made our operation
much more efficient. The calibration
status is posted daily on the AERONET website under ‘Operation’ if
you want to track the status of your instruments calibration. Site manager list, site photo page etc. are
all part of the relational database.
please track the health of your instruments at least weekly on the
AERONET website. Low sun and
cold in the northern hemisphere can cause power problems.
Often times tilting the solar panels toward the low sun solves
We’ve noted that the 340,
380 and 1,610 nm filters provided by Cimel (Spectragon)
cannot be used in the project due to inadequate blocking and/or spectral
mismatches. Other standard
IAD Spectragon filters will be accepted at this time as long as
we have the measured filter function. We don’t have information on
the long term stability of these filters however.
If the stability is shown to be poor, they will be dropped
from network use.
The network has two official calibration sites,
Goddard and Lille/Carpentras. Lille
handles approximately 30 instruments per year and Goddard the remaining
170 or so thus requiring we cycle out about 1instrument every 2 days. Ross Mitchell is ramping up as a calibration
site at CSIRO in Australia
and will handle mainly instruments from that region. AEROCAN is also considering this as a possibility
for a growing Canadian network as is Frank Wagner in Munich.
The distributed calibration procedures and protocols and intercomparisons
are being carefully plotted out to insure that all instruments are
referenced to the same standards with well established uncertainties.
New Sites and Field campaigns:
New sites were established
in the UAE, Algeria,
5 in N. America, 6 in Europe,
1 in Antarctica, 1 in the South
Indian ocean and only 2 in Asia
during the last 6 months. Until
new calibration sites are established both Lille
and GSFC calibration sites are not accepting new North American or
European participants. An independent
cimel network (20 + sites) is in operation in northern China. Formal and informal field campaigns are difficult
to define and track. The AEROENT
team has developed a SE Asia network of five
sites from last year’s field campaign.
AERONET stations participated in the GLAS validation campaign.
You may have noticed that
links to other data sets occasionally are available at some sites
from the AERONET download tool. These
sites will be expanding and data links increasing as part of the BAMGOMAS
integration effort that will provide backtrajectories,
Lidar, MODIS imagery and aerosol products,
model results for most of the AEROENT sites if the measurement is
available. Other data sets
will be linked as appropriate and will be provided as an integrated
website to facilitate analysis. As
AERONET users you will have the benefit of these links as they come
on line although bear in mind you are the gunnea
pigs during this development period.
It will not diminish access to AERONET data.
Publications and Research:
Research is our motivation
and reason for existence of AERONET.
Without a substantial research component that is integrated
into the daily operation of the project, the quality and quantity
of the data would suffer. Congratulations to Tom Eck and Alexander Smirnov
in particular for providing that difficult task with such competency
and still lead highly productive research lives. Operational issues often overwhelm our research
opportunities, so I note with awe and pride these senior authored
papers published in 2003 by our staff.
Many junior author papers were also published by our staff.