OVERSEAS TRAVEL REPORT
28/2/1997 - 11/4/1997
Bob Cechet
CSIRO Division of Atmospheric Research
Surface Processes Project
BACKGROUND:
I undertook the three main tasks listed below as part of an overseas trip that covered five nations and over five weeks of official business:
(i) MODIS Land Science Team field campaign (Death Valley, California);
(ii) European Remote Sensing (ERS) Symposium (Florence, Italy);
(iii) Visit Uni. of Nottingham and Rutherford Appleton Laboratory (both in U.K.) to discuss arrangements/logistics for ATSR-2 field campaign (ACEX)
FUNDING:
(i) & (iii) were funded by a COSSA EOC travel grant
(ii) was funded by a DIST travel grant
USA
I collaborated with Dr. Zhengming Wan (UCSB; EOS MODIS Land Surface Temp [LST] P.I.) and his team on a LST cal/val campaign in Death Valley, California. We spread an array of contact temperature sensors over a surface composed of mainly sand and small rock fragments. We also used a number of infrared radiometers including the new CSIRO radiometer AHDS to view a wide range of surface emissivity on the ground, while the MODIS Airborne Simulator (MAS) overflew the area (aboard the NASA ER2) during both daytime and nighttime missions.
The CSIRO radiometer performed very well, and the team were impressed by the manufacturing expertise displayed in the construction of the radiometer. Discussions are continuing regarding the manufacture of two radiometers for the MODIS team.
The MODIS team showed significant interest in CSIRO being involved in future international cal/val campaigns. During the field campaign we entered into discussions concerning a joint response to the latest NASA EOS validation Research Announcement (NRA-97-MTPE-03) in the context of the CSIRO method/concept of cal/val which includes both continuous monitoring and regular intensive field campaigns at well characterised field sites. The MODIS team were keen to collaborate and they already had plans to instrument a site in Nevada but did not have the experience with the remote logging technology to be confident of undertaking this task. CSIRO have the CSIDAT system which is running successfully at Hay & Alice Springs and 5 years experience in remote monitoring. We are collaborating on a response to the NASA RA which is due May 15th. I visited the Railroad Valley site (MODIS LST & ASTER preferred site) in central Nevada and the nearby Fallon Airforce Base to assess logistics and aircraft activity over the site. I found the site to be a large, flat and uniform flat silt playa (15 x 8 km) in an isolated part of Nevada with little if any airforce air-traffic overhead and no commercial air activity for 150 kilometres (rare indeed for the U.S.!).
My involvement in this field activity already is showing signs of bringing back dividends to both DAR and the EOC. Our continued involvement with UCSB in MODIS cal/val campaigns will no doubt enhance our expertise and also our reputation. These international activities will also assist in developing further useful collaboration and contacts for all EOC members, including further opportunities for external funding.
GERMANY & SWITZERLAND
I visited Dr. Peter Wendling of the Institute for the Physics of the Atmosphere, German Aerospace Research Establishment (GARE) at Oberpfaffenhofen (suburb of Munich). We discussed LW radiation measurements, particularly downwelling LW measurements from airborne platforms. Measurements of downwelling LW at altitude provide the most testing conditions for instrumentation. The DAR aircraft facility are interested in replacing their set of airborne LW instruments, and in my role as joint coordinator of EOC instrument pool, I investigated the efforts of the only institution that are developing improved instrumentation for these testing conditions. I am negotiating with GARE to loan an instrument to CSIRO (for assessment) following final airborne trails in the European summer of 1997.
I visited the Geography Institute of the Swiss Federal Institute of Technology (ETH) based at the University of Zurich. I initially met with Hans Gilgen (Global Energy Balance Archive [GEBA] data manager) and Hermann Hegner (Baseline Surface Radiation Network [BSRN] data manager). DAR plan to make our 5-year database of radiation measurements from the Hay CIGSN site available on GEBA, and I received solid support. CSIRO was strongly encouraged to update the Hay site so that it achieves the high standards set by the BSRN, due mainly to the high spatial uniformity of the site over a scale of 10's of kilometres. In the months prior to my overseas visit, I had set in motion a collaborative venture with the Bureau of Meteorology Radiation Unit (who operate a BSRN site at Alice Springs) in an effort to elevate the Hay site to BSRN standards. Unfortunately these efforts are currently stalled, and due to continuing financial constraints it is unlikely that interest in this collaboration will be re-energised in the new financial year.
Satellite imagery, photographs and data (mainly time-series of radiation parameters) were discussed with a number of other researchers. Martin Wild (also Geography Institute) was very keen to use the Hay CIGSN data as part of some radiation modelling work he is currently undertaking. Post-visit discussions have resulted in him successfully applying to visit DAR for a few weeks in June 1997. Hermann Hegner plans to briefly visit DAR following IAMAS in July 1997 to have further discussions concerning BSRN. He has enquired about the possibility of visiting the Hay CIGSN site.
I also visited the World Radiation Centre at Davos Dorf in the Swiss alps. I gave a presentation on CIGSN and later talked to Claus Frohlich and Chris Wehrling concerning broadband SW measurements/calibration and Rolf Philipona concerning broadband LW measurements/calibration. The EOC community believe that maintenance of accurate calibration parameters and procedures for both EOC & CSIRO instruments generally as an important task, especially when comparing datasets from different local sources. My particular interest in visiting centred around:
1. their pyrgeometer calibration facility (broadband LW hemispheric measurement) as the Australian Standard facility (constructed by DAR in 1965) needs updating;
2. their proposed use of an absolute radiometer for downwelling LW measurements and also in the calibration of field instruments (pyrgeometers).
I was not impressed with both the construction and the methods used for pyrgeometer calibration; I am currently discussing these matters with colleagues prior to responding in writing. The lack of technical support was evident in the construction and technology associated with the absolute radiometer. I am pleased to say that DAR is far ahead of the Swiss in the field of absolute infrared radiometry.
ITALY
I attended the 3RD ERS Symposium in Florence (5 days) sponsored by the European Space Agency (ESA). The meeting, attended by over 700 scientists and engineers (4 Australians; 1 CSIRO, 2 Uni. of Tas., 1 Uni. of S.A.), consisted of more than 450 papers focusing mainly on radar technology and applications. Fortunately, with four parallel sessions, the ATSR community (including passive microwave) were to some extent separated. Six sessions concerning ATSR applications were presented chiefly focusing on marine applications. Three speakers (including myself) gave presentations focusing on the surface radiation budget (SRB). There was a special working session on observations of land cover from ATSR data (DAR's main area of interest), which was poorly attended mainly due to the few papers in this area which were presented at the conference. ATSR measurements in the visible part of the spectrum have only been acquired since mid-1995 and the data has not been widely disseminated. Nevertheless, many valuable discussions were had with members of the ATSR community, as even with the marine group we have common ground in the areas of calibration, cloud-clearing and atmospheric correction. I was approached by Raymond Zaharia (responsible for Oceanographic Space Science at CNES) regarding applying to CNES for support of our SRB work as part of the French VEGETATION satellite program. I also presented a poster paper on the AMAP initiative (ATSR-2 Map of Australia Project), which aims to produce a number of ATSR derived demonstration products of the Australian continent for use by CSIRO and the general scientific community.
UNITED KINGDOM
As part of preparations for ACEX (ATSR-2 atmospheric Correction Experiment), I met with collaborators Mike Steven and Jerry Clark (Geography Dept. Nottingham University) at Nottingham. We discussed the first draft of the science plan and the logistics for the experiment. I also met George Mackay (Leicester University), whose earlier atmospheric transmission modelling work is being examined in the ACEX experiment, at the University of Nottingham (Sutton-Bonnington campus, near Leicester). He was genuinely interested in our SRB work, in particular the accurate determination of albedo using the ATSR 1.6mm channel. He indicated that he would be discussing our work with Prof. David Llewelyn-Jones in an effort to get the Leicester group more active in SRB studies.
During the majority of my 9 days in the U.K. I was based at the Rutherford Appleton Laboratory (RAL) near Oxford. I met with John Wright and Nigel Houghton concerning planning for the ACEX experiment. I had talks with Chris Mutlow (collaborator on AMAP initiative) regarding data availability for some coastal and persistently cloudy regions of the Australian continent, and I began browsing the more recent data acquired over Australia. I met with David Smith (ATSR-2 calibration scientist) regarding using data from the CIGSN sites as part of his routine calibration procedure. My visit was timely as he was having some problems with his Libyan Desert target site (not instrumented), probably due to dust storms. CIGSN data has already changed hands, and we look forward to a close relationship in the future. I also met with Albin Zavody who demonstrated his cloud-clearing software which will be made available to DAR in the near future.
At RAL, I had long discussions with two scientists (Phil Watts & Tim Nightingale) who are both keen to visit DAR for an extended period. Phil Watts is working in the area of cloud property retrieval using chiefly ATSR-2 data. We worked on a proposal involving our project and also Martin Platt, Reinout Boers and Peter Turner that would benefit both groups page 4 and would see him visiting DAR for a period of at least 6 months beginning late 1997. Tim Nightingale is an instrument engineer specialising in radiometer design and construction. His preliminary plans include visiting John Bennett and also participating in instrument comparisons (Ian Barton and William Skirving (AIMS) have also offered to assist in ship-board field comparisons).
The Australian blackbody radiation standard, built by DAR and currently operated by the Bureau of Meteorology, is in a state of gradual decay (natural aging!). It has performed poorly in recent round-robin instrument calibration comparisons, and we have been approached by BOM to assist in designing and building a new standard. Furthermore DAR plans to build a new calibration blackbody to enable accurate calibration of radiometers (such as the ARM radiometers, AVADS & AHDS, and a number of commercial radiometers). This facility would be made available to other CSIRO areas (i.e. calibration of SST radiometers and EOC instrument pool). I visited three laboratories (and had extensive discussions on the phone with another) in order to compile the information required to tackle this task. They were:
Bob Watkins
University of Oxford; designed/built/calibrated blackbodies for a number of space missions
Ian Mason
Mullard Space Science Laboratory (University College, London)
Rob Spurrett
AEA Technology (Culham Laboratory, Abingdon) Jointly manufactured blackbodies for ATSR/ATSR-2 & AATSR and currently manufacturing blackbodies for the Michaelson Interferometer for Passive Atmospheric Sounding (MIPAS)
Nigel Fox
National Physical Laboratory, U.K.
Most researchers were aware of the problem that there did not exist a blackbody standard (world standard) for broadband LW hemispheric viewing instruments and that a variety of national standards employing various techniques were currently used. Nigel Fox stated that "there existed a crisis in this area of atmospheric LW radiation measurement" due to the non-uniformity and incomplete calibration methods currently in use (a fact that few researchers seem to realise!). He asked me to present a paper on this topic at the upcoming Absolute Radiometry and Remote Sensing conference, NEWRAD97 (Nigel is the organising committee chairperson).