--M. Patrick McCormick (mcc@cs.hamptonu.edu), SAGE III Principal Investigator, Hampton University
A Science Team meeting for the Stratospheric Aerosol and Gas Experiment (SAGE III) was held at Hampton University (HU) in Hampton, Virginia on March 26-27, 1998. SAGE III, which is part of the Earth Observing System, is having three flight instruments developed, with its initial flight aboard the Russian Meteor-3M spacecraft in 1999 in a sun-synchronous orbit. The second flight will be flown on a flight of opportunity (FOO) into a mid-to-high inclination orbit, necessary in order to provide global coverage. The third SAGE III instrument will be flown aboard the International Space Station (ISS), now scheduled for mid-to-late 2002. SAGE III will measure, using solar occultation, 1 km vertically-resolved middle atmosphere profiles of ozone, aerosols and a number of aerosol properties, water vapor, temperature, nitrogen dioxide, and cloud presence. Additionally, using lunar occultation, SAGE III will measure nitrogen trioxide and chlorine dioxide.
The meeting began with a welcome by the SAGE III Principal Investigator, M. Patrick McCormick of the Center for Atmospheric Sciences (CAS) at Hampton University (HU). After introduction of all participants, he gave a brief overview of HU and its history, described CAS, announced that CAS's first atmospheric courses would be offered this fall, and encouraged everyone to tour the campus and visit the newly-renovated museum on campus. In the absence of the SAGE III Program Scientist, Jack Kaye of NASA Headquarters, Pat presented a summary prepared by Kaye of recent activities related to NASA's newly renamed Office of Earth Science (OES) and planned research announcements likely to be of interest to the SAGE III Science Team. He also announced that Ghassem Asrar was named Associate Administrator of Code Y.
Shahid Habib, of the Earth Science Systems Program Office and the SAGE III Program Integration Manager, provided information about the project, especially those activities associated with the delay in launching the first SAGE III instrument on Meteor-3M from August 1998 to May 1999, and the potential FOO mission using a Russian Resurs launch in late 2000. After discussions with the Russian Space Agency (RSA) senior management in December 1997, it was concluded that since the RSA could not guarantee a three-year mission life, it was better to delay the launch of Meteor-3M until May 1999. Under the new schedule SAGE III will be shipped to Baikonur in April 1999. The Zenit-2 launch vehicle with contamination-controlled fairing will be used with a guarantee of a three-year plus mission lifetime. Habib then presented material on the SAGE FOO activities, stressing the need for an early flight in an inclined orbit to provide global coverage. This flight is a must to ensure bridging the data gap between SAGE II and SAGE III/ISS, and extending the 20-year ozone and aerosol data record of SAGE I and SAGE II for global change studies. He described the opportunities to fly the SAGE III FOO on Resurs in a 64.8-degree inclined orbit and the ideal coverage it would provide. These mid-inclination missions are very rare and the Resurs-DK is the most promising opportunity in the foreseeable future. He presented data about the builders, Ts SKB-Progress, and showed drawings of the spacecraft with SAGE III aboard. He concluded that the Ts SKB-Progress team is very capable and experienced in dealing with the West; no major technical risks or mission impediments have been identified; this is a cost-effective solution as opposed to committing large amounts of NASA funds for building a separate inclined orbiting spacecraft and launch vehicle; and it represents an excellent opportunity that meets OES science priorities. Habib is preparing a "white paper" encouraging funding from OES.
With respect to SAGE III on the International Space Station (ISS), NASA is working with Brazil to get an Express Pallet, and the European Space Agency (ESA) has signed a phase C/D contract with Alenia/Italy to provide the Hexapod. With delays of ISS to perhaps 2003, it becomes even more critical to launch the SAGE III FOO in 2000. Stratospheric chlorine and its effects on ozone depletion are expected to peak in this time frame.
Debra Carraway, the SAGE III Deputy Project Manager, described the detailed instrument and project schedule and status. She gave additional details on the issues leading up to the delay of the Meteor-3M launch date. All indications were that a launch after May '99 would provide greater mission reliability due to enhanced integration and testing capability, better familiarization with spacecraft systems and procedures, less risk of contamination, and more-realistic staff work schedules. The current integration and test schedule was developed with a goal of May 15, 1999 for launch as this is the date NASA requested from the RSA, but there has yet to be confirmation by RSA. With the May 1999 date as a goal, the SAGE III flight model is to begin integration with the Meteor-3M in late November 1998 and de-mated after testing in February 1999. The spacecraft and SAGE III will be shipped separately to the Baikonur Cosmodrome in February 1999 and April 1999 respectively. After re-integrating and testing in Baikonur, the SAGE III and Meteor-3M will be launched aboard a Zenit-2 rocket. Debra then reviewed the FOO and ISS instrument status. Fabrication is proceeding on both flight units with critical subsystems almost completely assembled and tested on the FOO instrument and piece part fabrication 95% complete on the ISS instrument. Mission uniques for these instruments are being defined and completed as reasonable. For example, the ISS instrument contamination door is being modified for a heavier duty cycle.
Pat McCormick reviewed the history of attempts to find a FOO mission for SAGE III. This included interactions with the Koreans, Chinese, Japanese, Canadians, Brazilians, and French. Much effort was expended by SAGE III personnel and foreign groups in studying the possibility of accommodating SAGE III in an inclined orbit. The possibility of a small dedicated spacecraft on a PEGASUS launch was also studied. Pat reviewed the requirements for such a flight and its necessity, as concluded by every science advisory group asked to endorse the need to fly SAGE III in a high-inclination orbit concurrently with a sun-synchronous orbit. These recommendations have come on numerous occasions from the EOS Investigators Working Group (IWG), its Payload Panel, its Atmosphere Panel, and most recently from the NASA Biennial Chemistry Review. Pat pointed out that the Resurs mission has an optimum orbit and is the only one found by the SAGE III team that will be available in the foreseeable future.
Bill Chu discussed the concept and need for "go/no go" criteria for launching SAGE III. Chu and the team will put together various scenarios based on our science objectives and standard data products. This study will be developed for our next science team meeting and include minimum science requirements and minimum lifetime. Chu also reviewed the Charge Coupled Device (CCD) defect issues of red leakage and etaloning, describing three possible solutions that were investigated to date. The red leaks on the present detector are longwave of 700 nm, and a software correction is being developed. Chu also is looking at long exoatmospheric measurements for characterization of the red leakage, although he thinks this is not a problem because signals are ratioed in occultation. He thinks etaloning is more of a problem; Didier Rault and Bob Veiga are modeling the effects on the returned profile species.
Bob Veiga presented several SAGE III spectrometer/telescope measurements of bandpass made with a monochromator as the source, and with several discrete sources. Straylight response measurements were also presented. The spectral response (full width at half maximum) of the instrument was estimated using all the above measurements, and was shown to be between 1.2 and 1.5 nm in most of the science channels. The bandpass of the 1550-nm channel was also presented.
The problem of background-offset correction was discussed. Segment-gap data as well as data showing the red leakage into the serial registers were shown. The charge-transfer efficiency (CTE) mode was presented.
Finally, a set of measurements made with the SAGE III instrument at the system level in the thermal vacuum chamber were presented, with concentration on the etaloning effect in the near infrared (NIR) pixels.
Larry Thomason described the status of the SAGE III production algorithm. He began by showing a table of the channel numbers and spectral characteristics for each channel, including numbers of pixels over specific wavelengths and the target species for each channel. He then showed a detailed modular flow diagram for the solar retrieval algorithm stating that the algorithm has been implemented following the description in the Algorithm Theoretical Basis Documents (ATBDs) and that a functioning form of all models exists. He noted that the cloud product production will be produced monthly rather than real-time to avoid "version" problems at the Distributed Active Archive Center (DAAC). A number of loose ends are being completed including a new version of the spectroscopy tool and data base, which has not yet been incorporated in the operational software, and a new version of the clearing module needs to be incorporated. In addition, the temperature/pressure module requires high-altitude smoothing and a final convergence criterion. Thomason has some algorithm concerns centered around the Emissivity Growth Approximation (EGA) tool (it's slow), incorporation of "version 6" transmission improvements (from SAGE II), improvements in the needed spectroscopy, and instrument accommodation (point spread functions and background subtraction, etc.), but Thomason felt confident that everything is in place or will be in place to produce the required data products. In the area of testing, the SAGE III forward simulator will be used to simulate a range of atmospheric conditions to test the performance of the operational algorithm and proposed modifications. Also, simple event testing will be carried out for basic module-by-module algorithm performance. More-complex atmospheric event testing will be carried out, such as sunrise versus sunset performance, volcanic recovery, ozone hole, etc. All testing will be accomplished by the end of February 1999 with a software review in March.
Eric Shettle gave an update on the current status of molecular spectroscopy related to SAGE III, focusing on ozone and NO2. The major concern with the ozone absorption cross sections is not as much at the wavelengths primarily used to retrieve the ozone profiles (287-290 and 559-624 nm), but at wavelengths used to retrieve other species where ozone is a significant absorber. This is a particular issue in the SAGE III measurements in the oxygen A band (used to determine temperature & pressure profiles), and the water vapor measurements in the 933-958 nm spectral region. The problem is the lack of reliable measurements of the ozone cross sections at stratospheric temperatures (down to 180 K) in the near IR beyond 762 nm (which is in the middle of the oxygen A band). The uncertainties in the currently available ozone cross section data in this spectral region lead to potential systematic errors in the retrieved temperature of 8 K, 3% in the retrieved pressure, and 30% in the water vapor concentration near the peak of the ozone mixing ratio.
Shettle is a member of an international group currently reviewing several recent high-spectral-resolution measurements of the NO2 absorption cross sections covering the near UV to the near IR, with the goal of developing a recommended standard set of data to use for atmospheric measurements of NO2. The measurements include those from groups in France, Belgium, Germany, and the U.S. The data generally agree to better than 5%, and most of the measurements include the temperature dependence of the cross sections.
Victor Sothcott presented the process/method used to develop the code that will be used to develop a backbone, storage area, and to maintain the data products as they are calculated. With this method, they are able to implement each algorithm as an object that gets its input from the storage area and does not have to interface directly with any of the other algorithms. This allows one to easily plug in new or updated algorithms with very little trouble.
The snapshot of results currently being calculated looks pretty good. Transmission results, ozone results (using three methods for different altitude ranges), and aerosol results are all showing errors approximately £5%, which is felt to be good for the current state of each algorithm. As the algorithms mature and spectroscopy improves, the results will improve drastically.
Mike Rowland, the SAGE III Data Manager, discussed the focus of data management as it pertains to SAGE III. He went on to describe the development phase approach that the science software development team is using and how development methods have evolved over the life of the development cycle. He also described the scientist-programmer interface paradigm used in the LaRC Aerosol Research Branch to transmit algorithm requirements to the programmers and how both the scientist and programmer validate the resulting software modules. He described the software testing and validation procedures used with the science software. He provided a status of the development of quality assurance procedures and some of the specific activities that will occur during data processing. Rowland explained the configuration management procedures of the science software development effort and what procedures are to be used for data management during normal post-launch data processing. He reviewed the basic data flow of the experiment from instrument to release of the SAGE III data to the public. He presented an overview of the hardware arrangement of the SAGE III Science Computing Facility (SCF) and described its capabilities and science team interfacing features. He explained the current security features and procedures in operation at the SCF. Finally, Rowland presented a high-level schedule of the science software development activities based on a May 1999 launch of Meteor-3M.
Sudha Natarajan presented the SAGE III mission operations status. She talked about the SAGE III mission operation personnel organization chart, Meteor-3M mission configuration and upcoming scheduled events for Meteor-3M, flow of different software blocks on Meteor-3M mission development, and the ISS mission configuration status.
Chip Trepte presented an overview of the planned validation program for Meteor-3M/SAGE III and the major activities between June 1997 and June 2000. Trepte reported on a partnership formed between SAGE III and NASA's Upper Atmosphere Research Program (UARP), Atmospheric Effects of Aviation Project (AEAP), and the Atmospheric Chemistry Modeling and Analysis Program (ACMAP) to conduct the SAGE III Ozone Loss and Validation Experiment (SOLVE). This mission is a joint balloon and airborne measurement campaign to the Arctic designed to examine the processes that control polar to mid-latitude stratospheric ozone levels and aid in SAGE III validation. It is tentatively scheduled to span the period October 1999-March 2000 and will employ experiments for high altitude balloons and the DC-8 and ER-2 aircraft. A NASA Research Announcement for SOLVE will be released, perhaps this summer, inviting experimental and theory team proposals. Trepte presented the detailed SOLVE measurement objectives for all SAGE III-measured species and requirements for each.
He also described the project's coordination with the Network for Detection of Stratospheric Change (NDSC) for correlative measurements with SAGE III. A proposal from the SAGE III Principal Investigator (PI) was submitted to the NDSC coordination office at NASA Headquarters to formalize this cooperation. Trepte noted that three validation aids are under development at NASA LaRC: A data distribution system led by Larry Thomason, an isentropic trajectory package being developed by Brad Pierce and Duncan Fairlie, and a forward simulator being developed by Didier Rault. Finally, Trepte described the overall approach to SAGE III validation including self-consistency checks (solar/lunar events, alternate retrievals, and instrument data), use of the forward simulator, and the intercomparison by correlative measurements. Correlative measurement approaches were presented for each species to be measured by SAGE III.
Didier Rault reviewed his work on the development of a forward simulation of the SAGE III instrument being developed at Langley. The simulation provides radiation counts for each of the science channels and is presently being used in the preflight validation of the inversion algorithm for both solar and lunar occultation events.
Lynn Harvey presented a trajectory-based comparison of an UltraViolet DIfferential Absorption Lidar (UV-DIAL), SAGE II, and the HALogen Occultation Experiment (HALOE) ozone measurements during the 1996 Tropical Ozone Transfer Experiment/Vortex Ozone Transfer Experiment (TOTE/VOTE) DC-8 campaign, which illustrated the technique of trajectory mapping. SAGE II and HALOE coincidences due to initializing trajectories from occultations demonstrated the usefulness of airmass simulations. The advantages of trajectory analyses include providing a synoptic context for asynoptic data and improving data comparison and validation efforts through an increased number of coincident observations.
David Rind discussed validating SAGE III data with SAGE II data. Obviously, one of the prime methods of validating SAGE III data is to use SAGE II data (which have already been validated) for those gases/aerosols that both retrieve. As there is no certainty that SAGE II will still be flying, means and standard deviations of previous SAGE II data pre-Pinatubo have been prepared; the values have been gridded and placed on the standard pressure levels for each month as well as seasonally. Therefore, when a SAGE III retrieval is made, we will be able to quickly evaluate its relationship to past SAGE II values. When the values differ by more than one or two standard deviations, this approach will flag that retrieval as requiring increased scrutiny. As it would be advantageous for the SAGE II means/standard deviation to be available to the SAGE III team as a whole, Rind is considering generating a CD-ROM that would be distributed to all team members.
Although Linda Brown of JPL was not in attendance, she sent a set of overheads for Bill Chu to present and was available, via telephone, to answer any questions that arose. Brown was selected in the Fall of 1997 as part of the validation team for SAGE III via her proposal to NASA NRA EOS-AM/SAGE III. She is providing accurate line parameters for features of the oxygen A-band near 760 nm (13,100 cm-1). The desired accuracies are 1% for intensities and 5% for width. She noted that published laboratory intensities agree only to 10% in intensity. At this point in her work, she concludes her results agree with the HITRAN 1996 database for line intensities and that the SAGE III accuracy requirements for the oxygen A-band line parameters will be met. Her "one year" task will be completed on time. A new database will be created in June 1998 that will serve the needs of many applications, and if additional funding were provided, she could use the 8 long-path laboratory spectra of water data she has collected between 690 nm and 1000 nm to improve the accuracies of water line parameters.
Similar to Linda Brown, Stan Sander of JPL was selected as a SAGE III validation team member and could not attend, but sent Bill Chu a set of overheads to present for him. His goal is to measure NO3 vertical columns with the JPL Fourier Transform Spectrometer during SAGE III overpasses of Table Mountain, CA (34.4°N, 117.7°W). He will perform these measurements in the 651-667 nm spectral region using the moon as a light source. Sander has made NO3 measurements since his selection, improved the instrument's signal-to-noise ratio with a new Avalanche Photo Diode (APD) detector and better band-pass filters, developed an automated pointing system that tracks the moon using a CCD camera, frame grabber, and PC control of the Heliostat, adapted the NDSC-accepted algorithm for Fourier Transform InfraRed (FTIR) data reduction to work in the visible range, and is using the HITRAN-96 line list to remove interfering H2O lines from the NO3 data.
Gary Morris discussed the use of trajectory mapping in validating ozone measurements.Ozone profiles from March 1997, measured by SAGE II, were validated against those measured by HALOE using the trajectory mapping technique and the traditional coincidence approach. The trajectory mapping results compare favorably with results obtained using the traditional coincidence approach, even for long-duration trajectory calculations. Furthermore, trajectory mapping dramatically increases the number of observations that can be validated and the latitude range over which coincidences occur. By accounting for dynamical changes in the atmosphere over short temporal and geographic scales, trajectory mapping can reduce the observed variance between the data sets. Comparisons of trajectory-mapped HALOE and SAGE data from December 1993 with ozonesondes from Hohenpeissen-berg showed excellent agreement. These results suggest that trajectory mapping provides an effective tool for the validation of SAGE III data with data from other satellite, ground-based, and ozonesonde instruments.
Jacqueline Lenoble presented an overview of the planned European validation activities for SAGE III. She listed the various sites that will be making ozonesonde, ozone lidar, aerosol and temperature lidar, and balloon ozone and NO2 routine measurements. She also described the major balloon-borne instruments and special campaigns that can be organized at Esrange -Kiruna, Sweden. Finally, she described the 11 sites possible for ground-based total ozone column measurements.
Volker Mohnen discussed the ozonesonde network and proposed guidelines for ozone validation. Recent developments by the Committee on Earth Observation Satellites (CEOS)-Integrated Global Observing Strategy (IGOS) focusing on cal/val issues emphasize the need for "continuous" validation of a satellite sensor over its "lifetime." A pilot project on "ozone density" is presently proposed to CEOS-IGOS, whereby these validation activities required for all sensors are coordinated in such a way that ground-based facilities needed for sensor validation are "shared." In addition, all parameters needed for sensor validation should be traceable to national/international standards.
Following these guidelines, it is proposed to proceed as follows for the ozone validation: All ozonesondes flown in support of SAGE III profile validation must be "characterized/calibrated." This would involve the World Calibration Facility (WCF) for ozonesondes of the World Meteorological Organization's Global Atmospheric Watch program (WMO-GAW); carefully selected ozone launch stations would be designated for SAGE III ongoing validation activities. These stations would only launch "characterized" sondes as part of their regular launch schedule or as directed to maximize coincidence conditions; SOLVE will also use "characterized" ozonesondes; and the Southern Hemisphere Additional Ozonesondes (SHADOZ) program is considered an integral part of SAGE III long-term validation efforts (2 years). Again, it is imperative that sondes flown in this program also be "characterized" by the WMO-WCF.
Phil Russell of NASA Ames described early results of comparisons between different algorithms that separate the aerosol and trace gas contributions to extinction spectra like those to be produced by SAGE III. The objective is to evaluate the performance of the retrieval algorithms described in the SAGE III ATBDs by applying them and other algorithms to measurements made by the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14). Most of the AATS-14 spectral channels are matched to SAGE III channels. Results obtained by Beat Schmid of the Ames team were shown for two ozone-aerosol separation algorithms applied to AATS-14 optical depth spectra measured in the Aerosol Characterization Experiment (ACE-2) field campaign. This tropospheric data set may provide indications of the performance of SAGE III retrievals when they are extended downward from the stratosphere into the troposphere. The two algorithms (a SAGE III algorithm and a quadratic-fit algorithm) produced ozone values that agreed within about 5 Dobson Units (DU) for aerosol optical depths at 500 nm of less than 0.01, and within 10 DU for aerosol optical depths between 0.01 and 0.07. Differences were shown to approach 100 DU when aerosol optical depths at 500 nm were greater than 0.3.
Yuri Borisov discussed the following Central Aerological Observatory (CAO) activities. With respect to temperature and pressure algorithm inversions, the CAO is developing the analytical method for forward calculations of atmospheric O2 slant path transmission. There are some differences between line-by-line and analytical calculations based on the error calculations. The inversion part of the algorithm is based on the "fitting" of inverted T and P profile transmission to the "measured" one. The accuracy of the "simulated" inversion is better than 10 K. There was a detailed discussion of the T and P algorithm and the schedule for algorithm comparison was agreed upon. The algorithm for NO2, O3, and aerosol profile inversions using 26 spectral channels (290 nm, 430-450 nm, 600 nm bands) were discussed. The analysis demonstrated that utilizing the 430-450 nm channels improves the accuracy of O3 profile inversion, and "wrong" Rayleigh subtraction doesn't affect the NO2 and O3 retrieval. Separation of the total extinction into each species extinction provides better results than the separation of the total slant path optical depth. There is a systematic shift between profiles retrieved by those two approaches.
A plan for validating O3, H2O and validation at the Yakutsk and Salekhard stations was also presented. The proposal, however, supposes financial support for the soundings. The US side provided simulated SAGE III telemetry data and agreed to send their spectral data base to CAO.
Oleg V. Postylyakov discussed the Institute for Atmospheric Physics (IAP) activities. The IAP continues to develop a Russian validation network of NO2 profile observations. In September 1997, IAP carried out an intercomparison of instruments for NO2 profile measurements. Five instruments from Russian NO2 observational stations together with a mobile train-mounted instrument took part in the intercomparison. The referee of the intercomparison was Paul Johnston of the National Institute of Water and Atmosphere, Lauder, New Zealand, who represented the Network for the Detection of Stratospheric Change (NDSC). The results of the intercomparison will become available when the NDSC presents an official conclusion on the intercomparison. The IAP organized colleagues at Russian validation facilities in central Russia. Three observational sites (Obninsk, 36.2°E; Moscow/Dolgoprudnuy, 37.61°E; and Nizhniy Novgorod, in which the ozone vertical distribution can be measured by different methods, and Zvenigorod station, 36.47°E, observing NO2 profiles, are located along approximately one latitude line 55.5°N at the distance of about 700-800 km. These observations were supplemented by NO2 profile measurements using the mobile instrument near Nizhniy Novgorod. It was possible to obtain a few profiles of both O3 and NO2 along the SAGE II tangent to improve the quality of validation. During the last train expedition, TROIKA-4 in February 1998, UV and visible scattered solar radiation was measured to retrieve stratospheric O3 and NO3 vertical profiles. Algorithms for processing these data are now developed. Train expeditions will become a source of correlative data for validation in Siberia.
Amin Dharamsi presented measurements of oxygen A-band lines by modulation spectroscopy using single-mode diode lasers to measure the parameters of several oxygen A-Band lines. Each line is examined by using first, second, third, and fourth harmonic detection orders. Since Nth harmonic detection yields a signal with N+1 turning points, each set of harmonic detection order runs gives a large amount of experimental information.
Lines in the oxygen A-Band with integrated absorption cross-sections ranging from 10-24 cm-1 cm2 mol-1 to 10-27 cm-1 cm2 mol-1 have been measured. Several instances of overlapping lines were examined. It was shown that wavelength modulation spectroscopy allows one to accurately measure line separation and line strengths. One of the experimental results presented is the RQ (31, 32) line (5.06x 10-26 cm-1 cm2 mol-1). In the wavelength modulation experiments conducted, the absorption signal due to this line is affected by the wings of two adjacent lines, namely the RQ 27, 28 and RQ 25, 26 lines. These effects were discussed, and it was shown that each measurement in this region gives information about all three lines.
The effects of etaloning that tends to limit the signal-to-noise ratio in wavelength modulation experiments were discussed, and its was shown that use of higher harmonic detection can reduce the deleterious effects of such etaloning.
Dave Woods and Susan Walters gave a joint presentation on the planned SAGE III educational outreach program. A significant outreach program is being considered for SAGE III that will make the public aware of this NASA research and its benefits to the community as well as its educational benefits. The program should also stimulate a greater interest in science and, perhaps, influence career choices by exposing this research to school children. They are developing handouts, posters, brochures, and a web page on SAGE III. Also, they are developing related instructional materials that will help teachers. It is planned that presentations will be made to local students and teachers, and a nationwide network of science teachers will incorporate SAGE III materials in their classroom instruction. Finally, an inexpensive hands-on project will be developed that will allow students all over the world the opportunity to participate in our research. It is centered around a sun-photometer. Walters also presented a suggested logo for our outreach program and a questionnaire for the team to fill out reflecting their interest in participating in the outreach program.
Next Larry Thomason described the SAGE III homepage, how it is being redesigned, and ideas concerning on-line data browsing. The new project homepage will provide a unified site for secured SAGE III sites as well as links to other necessary pages. The public homepage is subdivided into subpages that concisely convey the key elements of the SAGE III project and provide, transparently, limited data browsing and ordering. It will introduce visitors to the project in a concise format for an informed non-specialist and is focused on explaining why it is important to the scientific community. It will allow visitors to perform up-to-date simple data browsing and ordering. Thomason showed the first page of the new homepage, which is a huge improvement over the old homepage. He also showed example data browser pages called the SAGE III Data Miner. They were quite impressive.
Rich McPeters, of NASA GSFC, presented an interesting overview of the Shuttle Ozone Limb Sounding Experiment (SOLSE) and the Limb Ozone Retrieval Experiment (LORE), which flew on the Shuttle in late November - early December 1997. Unfortunately, only two orbits of data were obtained by SOLSE and LORE. SOLSE is an imaging spectrometer with a CCD array detector having a vertical coverage of 30-60 km with 2-km resolution. The spectral coverage is 265-360 nm.
LORE is a multi-filter limb scattering instrument with a vertical coverage of 10-to-40 km and resolution of 2 km. It has channels at 345, 525, 600, 675, and 1000 nm. Rich showed preliminary data from an ozone profile comparison taken on December 2, 1997 between LORE (2°N, 15°W), SOLSE (3°S, 15°E), a balloon-borne ozonesonde launch from Ascension Island (8°S, 14°W), and an ozone zonal mean from HALOE. Limb scattering is a serious contender for future ozone profile measurements (e.g., in NPOESS) and, as such, this demonstration mission is important. Hopefully, another Shuttle flight of SOLSE/LORE will be accomplished. Limb scattering data will also be obtained by SAGE III. A cooperative effort between us and GSFC is being developed for working on these data.
Frank Schmidlin, of GSFC, presented SAGE III calibration/validation plans for lunar occultation measurements from the tropical sites in Brazil and Ascension Island. Approximately three balloon-borne ozonesonde measurements will be scheduled each month from each observation site. As part of the Memorandum of Understanding with Brazil, balloon ozonesonde observations will be made from the Instituto Nacional de Pesquisas Espaciais (INPE) site at Natal and probably from a university site at Alcantara. Measurements from Ascension Island, presently made weekly as part of a GSFC requirement, are scheduled to end in October 1999. This effort is arranged through the U.S. Air Force, which maintains a facility at Ascension. Observations for SAGE III will continue beyond October 1999. These tropical-site observations will also meet the requirements specified for the long-term weekly measurement program between NASA and INPE and the Southern Hemisphere Additional Ozonesondes (SHADOZ) experiment.
As in past SAGE programs, Pat McCormick assigns a science team member the responsibility to validate each measured species. In this manner, a scientist, other than the PI or a project team member, stands by the validation of each species. These leaders form subteams to accomplish this task, and are usually the senior author for subsequent validation papers. With respect to SAGE III, Phil Russell will be team leader for validating the aerosol products, Derek Cunnold the team leader for ozone, Geoffrey Kent for clouds, David Rind for water vapor, Jim Miller and Ron Nagatani for temperature and density, and Hope Michelsen for NO2, NO3, and OClO. Supporting all these teams will be a team developing trajectory techniques, 4-D simulators, and gaseous cross-section determinations. This team will be led by Chip Trepte with Eric Shettle leading the cross-section team. He also made assignments of science team members for each of the subteams. McCormick then showed a graphic of how these teams will be tied together to support the total SAGE III validation. He finished the open part of the science team meeting by requesting that, if they haven't already done it, all speakers should provide him with hard copies of their talks. These will be available from his office at HU if any member needs them.
The final session was a closed session for science team members only, in which many science team issues were addressed. These included: management issues including problems with the timing for their funding, discussions of future team activities including scheduling, ideas regarding the FOO, visiting scientists at HU or LaRC during validation and early data-use periods, their involvement in SOLVE and the PI's involvement in SOLVE, and their requirements for accessing data. The team was reminded of the need for developing "Go/No Go" criteria for launch, and were asked to provide Bill Chu with their thoughts before the next meeting. Finally, the team was reminded to send Pat two-page summaries of their SAGE III activities, status, and progress.
The meeting was adjourned by Pat McCormick at approximately 3:30 PM on Friday.