OVERSEAS VISIT REPORT

Ian Grant, CSIRO Division of Atmospheric Research
USA, Canada, UK and ENAMORS Conference, Finland

September 1997

During three weeks of September I visited the US, Canada, and the UK and attended the three-day ENAMORS Workshop in Finland, where I presented a poster.

USGS, FLAGSTAFF, ARIZONA, US

At the United States Geological Survey (USGS) labs in Flagstaff, Arizona, I met with Hugh Kieffer, Bob Wildey and James Anderson.

They were waiting for upgraded telescopes and were nearing completion of the programming of the real-time hardware control. They have been collecting good observations for several months now. A lot of work had gone into the programming of the real-time hardware control so that a night's observation program could run almost unattended.

They showed me their robotic lunar observatory, which is dedicated to establishing the moon as a spectral radiance standard for the calibration of earth-observing satellites. They had recently installed the SWIR imaging system alongside the existing VNIR system and are close to having a system which can routinely collect good observations unattended. Their analysis system requires a lot more development. A fixed Spectralon panel illuminated by NIST-calibrated standard lamps anchors the calibration. The observatory will participate in an intercomparison of radiometric standards, in which a travelling standard sensor will view their illuminated Spectralon panel. They commented that a recent international intercomparison of national radiometric standards found differences of up to 15%.

We discussed the analysis of the near-simultaneous images of the moon taken on 22 August 1997 by the GMS-5 satellite and the USGS observatory. This would aim to calibrate the GMS visible-band imager and so be the first demonstration of the calibration of a geostationary imager by the moon. They were interested in pursuing this in a collaborative paper, and saw it as a valuable check on their system. They will provide me with images in each of their narrowband channels, at their full-resolution and in the projection they would provide for any sensor. I will do the co-registration, wavelength interpolation and integration, and image comparison. We discussed methods of registration and resolution matching. The initial uncertainty of calibration could be as much as 15-20% but they expect this uncertainty for the 22 August image to decrease over the next year as they develop their analysis and better characterize their observing system. They saw the present uncertainty as no reason to delay the paper. They were interested in conducting monthly calibrations of GMS if this first result worked well.

CANADA CENTRE FOR REMOTE SENSING, OTTAWA

The main purpose was to talk to Zhanqing Li about his work on the remote sensing of surface albedo and net shortwave flux. Unfortunately, he was in China on business he had learned about only shortly before my trip commenced. I talked to Li's postdocs Alex Trishchenko and Linhong Kou.

Alex is a member of the ScaRaB team. He has examined the issue of narrowband to broadband conversion using ScaRaB data, which is uniquely suited to studying the problem since it has both a broadband shortwave channel and one resembling AVHRR's channel1, giving simultaneous and colocated measurements in narrow and broad bands. Parameterizing the linear conversion coefficients in terms of solar zenith angle, for two ARM sites, improved the retrieval of shortwave fluxes by typically about 10W/sq m. He has further studied the conversion with radiative transfer simulations and surface models. The conversion is dependent on surface type, solar zenith angle, water vapour amount, aerosol amount, ozone amount, cloud height, and so on. He concludes that in at least some of the studies of atmospheric shortwave absorption which use GOES visible-band data, the narrow-to-broadband conversion, and the GOES visible calibration, are in error; replacing the conversion brings the observations into agreement with radiative transfer theory, removing the shortwave absorption anomaly. Alex is interested in working with the CIGSN upwelling shortwave data.

Linhong Kou has measured the aerosol radiative forcing at the BOREAS site, using ground sunphotometer and GOES VIS data.

I met with co-authors at the Herzberg Institute for Astrophysics to review progress on and plan the completion of a paper on work which was started several years ago, and on which I have taken the lead in writing up. The paper examines a complicated oscillatory event in the electrodynamics of the polar ionosphere during the great magnetic storm of March 1989.

Overview of ATSR series

ATSR-2 is in good health, and its scan mirror problem appears ever more rarely. The calibration of the four shortwave channels has been examined with several methods and the results, including those from the ACEX campaign, agree to within about 2%. The anomalous factor of 1.4 in the 1.6mm calibration has been traced to the use of the reflection coefficient for the wrong metal for a mirror surface. I have a draft report which collates all of the visible calibration methods and results, including the contribution of our ACEX campaign. Dave Smith has identified and modelled several problems in the onboard calibration system (OBC). He has a good understanding of that system and some improvements have been incorporated into the AATSR OBC. The ATSR-2 calibrations on the web have been updated in the last few months and are likely to be again soon.

The polarization sensitivity of AATSR has been characterized by an Australian group: while it is less than about 10% for the 555nm, 670nm, and 870nm channels, it is about 40% for the 1.6mm channel. The polarization sensitivity of ATSR-2 is unmeasured but is presumably similar.

Reprocessing of the entire ATSR-2 archive is expected to finally start at the beginning of October. It will begin with September 1995 data and proceed at four times real time, thus completing by March. The requested products for the CIGSN sites will accumulate in an FTP area.

ESA continues to activate ATSR(-1) on a rigid schedule of three consecutive days out of every seventy, and RAL receive the data. RAL's archives of ATSR data are still incomplete.

AATSR will be delivered to RAL in October to begin calibration. Dave Smith showed me over the rig for doing the calibration in vacuum and in thermal conditions as close as possible to what the instrument will experience in operation.

ATSR-2 cloud property retrieval

Phil Watts demonstrated the software he is making available to us for examining ATSR-2 imagery, which emphasises the retrieval of cloud properties. It is a very capable, flexible and useable graphical tool written in IDL. It fits water/ice cloud models from a look-up table generated by DISORT.

Anthony Baran is working on ATSR-2 ice cloud retrievals, based on an anomalous diffraction theory. He uses complex particle shapes (habits) including columns and polycrystals, which avoids the haloes of ice spheres and cylinders. He uses ATSR-2's dual view to retrieve the particle habit, then a single view to retrieve the properties. Phil has incorporated the ice retrieval scheme into his code. They have identified 60% of the cirrus blowing off the tops of tropical cumulus anvils to have a polycrystalline habit.

Anthony has also examined ground-based IR interferometer observations of cirrus. He finds a linear length of spectrum near 10mm, the slope of which depends on ice particle size and could be measured with a low-resolution interferometer.

ATSR-2 shortwave calibration

I learnt that the pre-launch validation of the ATSR-2 shortwave channels could have been invalidated by work to fix a pre-amp problem which was discovered after the calibration.

Dave Smith has well characterized the on-board calibration (OBC) system, which directs sunlight into the optical train via a diffuse reflector. A continually thickening layer of condensate on cold optical elements of the OBC is evidenced by a wavelength-dependent oscillation in its results. Dave is able to derive a correction. Condensate on the field stop superimposes a trend of decreasing responsivity. Periodic warming of the optics restores the original responsivity. The rate of condensation decreases as the spacecraft ages.

Baffling of the OBC partly occults the sun twice per year. Dave fits a curve to the 1.6mm channel and uses it to correct the other three shortwave channels. The baffling for AATSR has been widened.

The responsivity was mapped across the instantaneous field of view (IFOV) for each channel before launch. For ATSR-2 the four shortwave channels are all close to the ideal of flat response over a rectangle with sharp drop-offs at the edges, unlike ATSR's IFOVs of roughly triangular cross-section.

Dave has used the Libyan desert to monitor instrument drift. He has removed angular effects by modelling them as a function of just one parameter: the sun-target-sensor angle. I offered to try to reduce the scatter further with the more sophisticated models being explored at DAR - he was enthusiastic and has sent his time series of radiances. This could lead to a better characterization of the Libyan desert site, which is widely used, particularly for AVHRR calibration. Indeed, Dave has started working with Rao of NOAA NESDIS on this. Dave intends to look at the ATSR-2 time series for the Tinga Tingana site, in response to Fred Prata's suggestion.

GOME

GOME is a spectrometer on the ERS-2 platform which measures well-calibrated 240-790nm spectra in the same location as ATSR-2 but with a pixel size of 40 km or more. I met Brian Kerridge and Richard Siddans of the GOME team, and requested spectra (300-790nm) at the CIGSN locations for the six ACEX passes. I think they are likely to be useful in testing the ACEX atmospheric correction, and in establishing how well the sites represent the mean spectral reflectance of the surrounding region out to a few tens of kilometres. I also got the URL for the GOME column ozone product - having total ozone matching ATSR-2 data in time and location will improve the aerosol retrievals from the shadowband radiometer and the ACEX atmospheric correction.

Other

Albin Zavody outlined his ATSR-2 cloud detection scheme. It differs very little from the ATSR scheme (it does not use the new ATSR-2 shortwave channels), and again is only suited to ocean scenes. It makes only slight use of the dual views. He will send us the detailed algorithm description when it is complete in October.

John Wright explained the ATSR-2 scan mirror problem to me, and the current operation of ATSR. Global maps of the coverage at the high data rate were to appear on the web two weeks after my visit.

Nigel Houghton described the expected commencement soon of the ATSR-2 reprocessing.

I met Chris Mutlow and John Ballard.

Tim Nightingale described the SISTeR radiometer he developed to validate ATSR sea surface temperature retrievals. The last of three campaigns in Mutsu Bay, Japan has been completed, and he believes the instrument has reached maturity. Tim is looking for cruises of opportunity on which he can deploy the radiometer.

David Newnham runs an FTIR spectrometer for John Ballard as a national facility for laboratory measurements of the spectra of gases over a large range of temperatures, pressures and dilutions. Paths through the gas from 25 cm to 600 m long are available. He recently improved the accuracy of the spectral parameters of the oxygen A-band, with measurements at temperatures of 223 K and 283 K and pressures of 100 hPa and 1000 hPa. He was aware of Denis O'Brien's work on A-band measurements. David has started to measure the optical properties of aerosols manufactured to have the chemical composition and size expected of those in the atmosphere. He is also working with Keith Shine from Reading in making measurements of the solar direct beam to investigate the shortwave absorption anomaly.

I met with Mike Lockwood, a world authority on the high-latitude noon-sector ionosphere/magnetosphere, and discussed the latest thinking on phenomena relevant to the interpretation of the March 1989 data I am writing up. He agreed to look over the finished manuscript.

GERB

I spoke to John Harries, who is the PI for the Geostationary Earth Radiation Budget (GERB) instrument to be flown on the first or second Meteosat Second Generation (MSG) satellite. GERB will be the first space instrument to monitor a region of the earth essentially continuously with sensors with the broadband spectral coverage essential for accurate radiation budget measurements. GERB will complement the higher resolution, narrower channel SEVIRI instrument on the MSG platform, and John particularly stressed that GERB would complement polar orbiting instruments such as CERES. Although GERB will not see validation sites in Australia, John was very keen that the Surface Processes Project lead surface radiation studies with GERB since there was a large hole in the surface part of the GERB Science Plan. He also asked that we consider joining validation campaigns in Africa. He had a high opinion of DAR. GERBs are planned for subsequent MSG satellites. At my suggestion he started thinking about approaching the Japanese about putting a GERB on a GMS satellite, which would place it over Australia.

ATSR-2 aerosol retrieval

I spoke to Joanna Haigh about the ATSR-2 retrieval scheme for aerosol over land developed by her former student Roland Flowerdew. The CIGSN sites are suitable to validate the retrieval, since they are large uniform areas for which we have a large store of ATSR-2 passes, we have measured aerosol optical depth at the Hay site for several months, and the surface reflectance properties have been measured at least during campaigns. Both were very keen to collaborate on a validation and offered to send code as necessary and do whatever work they could. I was concerned that the rural Australian air is so clean that the aerosol amount is too little to retrieve accurately. However, Joanna told me that Flowerdew's scheme can be adapted to take whatever information is known about the surface and/or aerosols and retrieve the unknown parameters; it may be most appropriate at the Australian sites to specify the measured aerosol and validate the retrieved surface reflectance properties. However, some days at Hay are hazy.

Flowerdew's scheme relies on the assumption that the ratio of surface reflectances is the independent of wavelength. I doubt very much that this holds for all surfaces: at Amburla in April 1997 the site appeared as mostly red soil in the nadir, but as a solid expanse of yellow dry grass when viewing towards the horizon. I suspect that the assumption will work better at Hay. Flowerdew had tested the assumption only using models of vegetation. Although vegetation models presumably have some foundation in observation, I suggested that an important step was to validate the assumption with field measurements, such as those we made during the ACEX campaign.

Joanna has an interest in the effect of the thickness of cirrus on cirrus property retrievals. She also noted that Chris Godsalve from Reading has just developed a radiative transfer code which can use an arbitrary surface BRDF.

I met with Mike Steven, Genevieve Rondeaux and Jerry Clark to discuss the completion of the analysis of the ACEX (ATSR-2 Atmospheric Correction Experiment) campaign which was held at Uardry and Amburla in early 1997. We reviewed the data CSIRO and UofN each had and identified the remaining data which needed to be exchanged. We planned the scope and authorship of three papers. Prata and Grant will be co-authors on two of these: one characterizing the two CSIRO sites and describing the CSIRO measurement methods, the other on the calibration of the four ATSR-2 shortwave channels resulting from the Australian campaign together with two earlier UofN northern hemisphere campaigns. The third paper, authored by UofN alone, will compare and validate the atmospheric correction schemes of Mackay and others. I brought back a report on UofN's analysis to date.

Genevieve will send me her measurements of upwelling spectral radiance at each measured location; for Hay this is 15 locations well distributed over 3 X 3km. This will permit me to accurately quantify the variability of the sites with respect to spectral radiance for a greater variety of directional radiance than I had begun to do before the visit using the airborne scanner and satellite data that we acquired during the campaigns. Furthermore, I realized during discussions at Nottingham that I can use the combination of the multiple-site surface measurements with the airborne and satellite data to examine the scaling of spectral BRDF at the sites from the scale of metres to kilometres.

It also became apparent during the discussion that the ATSR-2 passes were possibly misregistered with respect to the Daedalus image by 1-2 km. I learnt at RAL that a navigation error of this size can be expected; it is unimportant for the SST which is ATSR-2's primary product, but inspection of the Daedalus imagery reveals that misregistration could introduce changes in the radiance of single pixels of order 10% at the Hay site. I committed myself to deriving nudges for each of the six ATSR-2 passes of the campaign. I suggest that ungridded ATSR-2 radiances be ordered to allow the least ambiguous assignment of ground measurements to satellite IFOVs.

One of the campaign's objectives was to validate the ATSR-2 atmospheric correction scheme developed at UofN by George Mackay around the 5S radiative transfer code. This scheme makes the assumption that in the absence of atmospheric effects the ratio of forward-to-nadir reflectance is the same at two wavelengths, for pairs of ATSR-2 shortwave wavelengths which are selected according to surface type - an assumption similar to that of Roland Flowerdew's aerosol retrieval scheme. The scheme adjusts the aerosol amount until the atmospherically-corrected reflectances satisfy that assumption, but Genevieve was finding that no sensible aerosol amount would work. I expressed concern that the assumption was violated by the Amburla surface during the campaign, and pointed out that her ACEX ground measurements permitted her to check the assumption directly, independently of atmospheric correction. I suggested that plotting the ratio of the measured surface spectral reflectance at the two ATSR-2 view directions versus wavelength, as a continuous spectrum from 0.3-2.5mm, would be particularly instructive.

UofN had not yet analysed their spectral irradiance measurements because they had only just received the LiCor instrument calibration from NERC. They will send us their calibrated measurements. This will allow a check on the absolute calibrations of the DAR and EOC shadowband radiometers - the factory calibrations of those two instruments disagree unreasonably.

While at UofN I spoke by phone to Andrew Wilson, who is responsible for NERC's Daedalus scanner. NERC has not seen a problem like the one recently discovered to have affected Australia's Daedalus over the last few years. However, NERC are building a rig to calibrate their scanner across the full swath width, rather than just the middle which is done by the rig that Daedalus's manufacturer provides.

I met with David Llewellyn-Jones, PI for ATSR and ATSR-2, and his group. David pointed out that the NERC Board for remote sensing had just been terminated, leaving proposals with a remote sensing component to compete with all others in their respective fields. He predicted that an immediate consequence would be the disappearance of pressure for the development of better satellite sensors and the disappearance of the expertise to do it. These sentiments were echoed precisely by a senior NERC remote sensing specialist at the ENAMORS meeting.

Sean Lawrence remains interested in collaborating with Fred Prata on using ATSR data at the CIGSN sites to study thermal land processes which couple the surface and atmosphere in climate models.

Vegetation structure from dual view

Andrew Shepherd is a student near completion of a thesis which aims to derive the land evaporation rate from ATSR. He feels his most significant advance is the use of dual-view thermal IR measurements to estimate the fractions of vegetation and bare soil on a surface, validated with field measurements in Zimbabwe. This appeared to me to offer a potential way of monitoring the state of the vegetation at our validation sites between campaigns. It might also provide a partial physical underpinning of spectral vegetation indices.

This meeting was held to plan European remote sensing of the land surface under Framework Programme 5 (FP5), an EC-funded four-year scheme to fund research projects aimed at developing remote sensing applications with clearly identified users. Global measurements were encouraged. Besides the European participants, representatives from Japan (EORC), the US (NASA), Canada and Australia (me and David Jupp) attended. David Jupp's report makes comments on the meeting complementary to those here.

I presented a poster on the CIGSN sites, including some recent results from the ACEX campaign for ATSR-2, which will be submitted to the workshop proceedings.

ENAMORS (European Network for the development of Advanced Models to interpret Optical Remote Sensing data over terrestrial environments) is a Concerted Action funded by European Commission DG-XII Environment & Climate Programme. It promotes Europe-wide remote sensing activity through, for example, joint publication, exchanges of personnel, and code sharing. Another ENAMORS meeting will be held in 12-18 months.

I have the book of abstracts. A proceedings will be widely distributed. Talk topics included vegetation physical properties, hydrology, forest monitoring, irrigation, ground instrumentation, fire detection, and sensor development. The following list of highlights is not exhaustive, but has a bias towards the atmosphere and surface radiation budget.

Highlights

Alan Cross of DG-XII set the parameters for FP5. He noted that FP4 supported over 50 pilot projects in methodological (research) and pre-operational applications. A key criterion for FP4 project selection was the involvement of users. Other speakers noted that one of the biggest and most successful projects was MARS (Monitoring Agriculture with Remote Sensing). Priority issues for the next five years include:

• environmental monitoring;
• EC agricultural policy (verification of subsidy claims);
• hazard mitigation;
• compliance with international conventions (e.g. desertification, wetland protection);
• development and humanitarian aid.

Alan expected that government funding for earth observation (EO) would decrease, and that the survival of European EO depended on paying users (including government and researchers). The EC Proposal for FP5 supports environmental monitoring and resources and ecosystem management ``by the development of generic technologies, notably satellites''.

Anne Jochum's talk ``The role of remote sensing in land-surface experiments in the frame of BAHC (Biological Aspects of the Hydrological Cycle) and ISLSCP (International Satellite Land Surface Climatology Project)'' noted that a tropical forest management system, including an operational airborne remote sensing component, is being developed for Indonesia. She also noted the development of an airborne aerosol lidar.

Jean Verdebout of Europe's Centre for Earth Observation mentioned SEARRI, a system to monitor wetland rice areas in south-east Asia (for agronomists and the measurement of methane for climate studies) based mainly on the SAR on ERS, and CLAUS (Cloud Archive User System) which provides global half-hourly thermal imagery for climatologists and which is transparent with respect to which geostationary satellite provides the data. He noted that short descriptions of 170 case studies of applications projects are on the web through EWSE at http:ewse.ceo.org.

Yves Govaerts of EUMETSAT spoke on the SEVIRI (Spinning Enhanced Visible and InfraRed Imager) instrument to be launched on the Meteosat Second Generation Satellite (MSG) in 2000. SEVIRI will have 12 channels with a resolution of 1-3 km. He pointed out that SEVIRI will give much more information on diurnal variations of surface reflectance than does AVHRR. The MET-5 geostationary satellite will be moved from longitude 0deg to 65deg E for the INDOEX experiment in 1998-1999.

Johannes Schmetz talked about EUMETSAT's plans more generally. A requirement to monitor climate and search for climate change is soon to be formally added to EUMETSAT's mandate. Future platforms include the EUMETSAT Polar System (which includes an infrared interferometer), the MSG series of geostationary satellites, and the Joint Polar System which is planned to operate from the middle of next decade in cooperation with the US. Johannes made the interesting observation that satellite imagers were not taken seriously by meteorologists in 1977.

Wolfgang Lucht of Boston University described experiments in using the Ambrals BRDF model to separate the albedo of vegetated surfaces into three contributions which he labels overall (isotropic) reflection, volume reflection (due to leaf arrangement), and geometric-optics (incorporating shadowing). The aim is to extract some information on the vegetation structure.

Madis Sulev of Tartu Observatory, Estonia, presented measurements of the radiation within a canopy with an interesting experimental arrangement which moved a pair of pyranometers on a travelling carriage through the canopy at various heights.

Joel Noilhan described a 10 km-resolution landcover classification of Europe. He stressed the need for a high-resolution vegetation map with global coverage; much of the globe is presently described no better than by the 1-degree Henderson-Sellers scheme. He also expressed the desire for better monthly estimates of albedo and vegetation properties.

Eric Lambin made the point that landcover categories are often proxies for biophysical variables, that earth observation can retrieve continuously-valued variables, and hence that change detection should examine continuous variables rather than search for conversions between discrete classes. Michel Verstraete further commented that continuous physical variables can be validated better than (unstandardized) landcover classes. These observations complement that of another participant: that surface processes should be studied at the spatial scale of the energy exchange rather than at the scale of some intermediate variable such as those describing vegetation structure.

Ghassem Asrar of NASA MTPE described MTPE's priorities for 1997-2002:

• seasonal to interannual climate variability - improved forecasts of transient anomalies;
• long-term climate change;
• atmospheric chemistry and ozone;
• landcover use/change;
• natural hazards.

Tamotsu Igarashi of NASDA EORC described the status of some ADEOS products (the distribution of AVNIR and OCTS products to general users began in mid-1997), and described upcoming Japanese missions. Missions under consideration include ALOS (Advanced Land Observation System), which will include optical sensors with 2.5-10 m resolution and is proposed for a 2002 launch, ADEOS-3 for a 2005 launch, and a technical small satellite with a lidar for cirrus and aerosol investigations.

Gilbert Saint described the VEGETATION instrument to be launched on the SPOT-4 satellite in March 1998. One of its main objectives is to describe the spatial and temporal distribution of the radiative properties of surfaces. It has several shortwave bands, 1-km resolution over the whole FOV (it is not a scanner), it can view up to 50deg off-nadir, its radiometric calibration will be accurate to better than 5%, and it will give global coverage daily over land, through sufficient onboard memory and one principal reception station. The project would welcome suggestions for atmospheric correction better than the 6S scheme it uses now. VEGETATION's web address is http:\\www.vegetation.cst.cnes.fr:8050/.

John MacDonald of the Canadian company MacDonald Dettwiler stressed that earth observation is an information business, and that for the industry to pay its way it had to provide routine information which was perceived by users as having value (economic, social, strategic or political value). He commented that scientific users of EO generate knowledge, while operational users generate wealth. He introduced the concept of a ``knowledge gap'' which separated those who converted radiances to physical parameters and those who have information needs. From this point on the Workshop's discussion repeatedly returned to this knowledge gap. John suggested that all EO sensors should be accompanied by a small optical instrument with 100-300 m resolution and bands suited to measuring the water vapour and aerosol parameters required to make accurate atmospheric corrections. Ultimately the user should be able to easily access data and products in the quantity he needs: ``by the pixel or by the continent, and paid for by credit card''.

Michael Rast of ESA noted that a strong interest in land applications was evidenced by the fact that even though the ERS-1 and ERS-2 satellites were dedicated to measuring ocean and ice, 65-70% of the papers they had produced in recent years were on land studies. He described ESA's programmes to develop Earth Explorer missions for research and one-off demonstrations, and Earth Watch missions for pre-operational monitoring. Earth Explorer candidates include a Land-Surface Processes and Interactions mission in polar orbit with a VISSWIR hyperspectral imager, and a Radiation and Topography mission. ENVISAT is planned to have a more user-friendly ground segment than ERS-12: a standard data format, a standard user interface, and online browsing for all imagery. ESA has supported and will support it in situ and airborne campaigns, and will support algorithm development and post-docs.

Jose Moreno of University of Valencia noted that whereas NASA's EO plan has clearly identified the three components of space segment, ground segment and algorithms, and validation/field campaigns, Europe had not yet clearly identified these three.

Some conclusions at the end of the final Workshop discussion were: retrieved physical variables must be converted to information which is valued by the users; a pre-requisite is that the data be readily available to users (it is already available to the scientists); NASA's experience is that neither funding the researchers nor the users to find the other has closed the gap between them. NASA is now trying a new model wherein joint proposals are sought in which researchers and users identify gaps to be filled, leading to something that the user can take over; there was only one user at the meeting; users don't want data, they want information; for many applications, EO was only part of the solution - other data sources were required.

Among my private discussions:

I discussed with Wolfgang Lucht the BRDF modeling being done at DAR and the study of BRDF scaling with ACEX data that I am considering. Wolfgang was interested in the potential of the Australian calval sites for studies useful to MODIS. He noted that NASA/EOS is aware of Australia's sites, infrastructure and expertise. While the MODIS team are now occupied with operationalizing their algorithms, they will soon turn their attention to calval planning. Wolfgang commented that while broadband shortwave albedo would be a useful validation measurement, better would be VIS and NIR albedos.

Gilbert Saint was interested in the potential of DAR and the Australian sites for the validation of VEGETATION's land surface products, and directed me to the AO for validation on the VEGETATION web site.

I was able to discuss lunar calibration of the Meteosat series of geostationary satellites with Johannes Schmetz and Yves Govaerts of EUMETSAT. They were keen to cooperate with me to exploit this calibration technique and have offered to schedule moon scans at times of my choosing. This is feasible because at the time of the meeting there were three satellites active: MET-5 is dormant as a backup, MET-6 is operational and MET-7 is undergoing commissioning. In fact, EUMETSAT already schedule moon scans during the commissioning phase to intercalibrate the satellites through histogram comparison.

Schmetz and Govaerts were very interested in the techniques used in our ACEX ATSR-2 validation, since they plan to vicariously calibrate the Meteosat VIS sensor with airborne campaigns over the Tunisian Desert.

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