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THE EARTH OBSERVER ____________________________________________________________________ An EOS Periodical of Timely News and Events July/Aug 1991 ____________________________________________________________________ Vol. 3, No. 5 EDITOR'S CORNER This is a frustrating editorial Many decisions will have to be to write, because it will be ob- made about EOS implementation in solete by the finish of the the coming months. It is, OESIWG meeting in Seattle. therefore, critical that the IWG express clearly the scientific As many of you are aware, both priorities and approach to EOS the Senate and House Appropria- in the context of the policy tions bills for FY 1992, which questions that our science must include funding for NASA, have address. The science strategy been passed. The conference for EOS needs to be refined and committee meeting to resolve the put in the context of the sci- differences in these two bills ence and policy questions that is expected in September, and we face. At the IWG meeting in the final bill will likely late August, we will focus on require some changes in the im- the framework for making deci- plementation of EOS. Congress sions on EOS priorities. Be- expects to finish discussions of cause of budget constraints and this bill before the end of uncertainties, NASA must re- October. structure the EOS mission, and it will need substantial advice The environment for EOS has from the Payload Panel during changed in three ways: this Fall. 1. The House and Senate markups Jeff Dozier of the EOS budget are sub- EOS Project Scientist stantially less than the President's submission. It is -------------------------------- clear that the EOS configura- tion must allow for future EOS PROJECT SCIENCE OFFICE fiscal uncertainties. Some of you may be unaware that 2. Atlas IIA and Titan III Jeff Dozier has a number of rockets might be available people located at or near God- for polar launches from the dard Space Flight Center (GSFC) Western Space and Missile who assist him in his position Center in the EOS-A time- as the EOS Project Scientist. frame. The pad can possibly This group constitutes the be upgraded to accommodate Project Science Office (PSO). the Atlas IIAS. Atlas IIA While Dozier coordinates most of and Titan III can launch the work with the "outside God- payloads roughly one-third dard" world, and GSFC senior the size of the EOS-A plat- management, the PSO coordinates form. the work directly with the three 3. The use of formation flying EOS project offices. Following to achieve most simultaneity are some of the people and the requirements appears viable. activities involved. EARTH OBSERVER Page 2 ___________________________________________________________________ Robert Price, Deputy Director of and ice. the Goddard Earth Science Direc- torate, serves as the EOS Pro- Support contractors perform a ject Scientist for Data. He number of tasks in support of works directly with the EOS the EOS project. A few are Ground Systems and Operations listed below to give you an idea Project to assure that the sci- of their individual duties. ence issues are addressed on a day-to-day basis. Price's posi- ST Systems Corporation (STX) is tion as EOSDIS Source Evaluation one of three PSO support con- Board chairman has given him tractors. Charlotte Griner, detailed insight into the capa- Task Leader, handles all of the bilities that EOSDIS must have coordination and administration. to meet the scientific needs for She is managing editor of THE the next decade. EARTH OBSERVER and maintains both the EOS information and Bruce Guenther serves as the viewgraph libraries. Griner and Project Scientist for the Ob- her staff provide support for servatory, and interfaces di- EOS booths at scientific conven- rectly with Chris Scolese, tions and meetings, using exhib- Project Manager for the EOS Ob- its and a variety of EOS-related servatory Project. Guenther videos and brochures. She is also serves on the EOS Calibra- assisted directly by Debe Tighe tion and Validation Panel with and Linda Carter. Renny Green- Moustafa Chahine, and is a stone provides scientific sup- member of the Committee on Earth port, and is currently acting as Observations Satellites (CEOS) the EOS historian to document Calibration and Validation the development of this large Working Group. new Earth science initiative. Bill Bandeen provides scientific Les Thompson serves as the support and coordinates the Project Scientist for the In- details of the aircraft program struments, and works with Marty for our investigators. Donohoe, Project Manager for the Instruments Project. He knows Mitch Hobish and Phil Ardanuy of all of the instrument managers Research and Data Systems Corpo- and is aware of the technical ration (RDC), provide general issues for each instrument. scientific support, often in the Thompson is closely monitoring form of quick turnaround analy- information introducing the idea ses and comparisons. RDC has that the EOS instruments could extensive experience in the be made much smaller and still scientific analysis of satellite meet the scientific require- data. ments. Birch & Davis Associates, Inc. For discipline scientific sup- provide logistics support for port with the Earth Sciences the Investigator's Working Group Directorate, we rely primarily (IWG), Science Executive Commit- on Darrel Williams for land, tee (SEC), and Payload Panel Skip Reber for atmospheres, and Meetings, coordinated through Antonio Busalacchi for oceans Debbie Critchfield and her EARTH OBSERVER Page 3 ___________________________________________________________________ assistants, Jan Hostetter and satellites, European and Japa- Cathy Freeland. nese satellites, and EOS, with the intent of synergistically As manager of the EOS Project answering key questions on Science Office, I work with decadal-scale changes in the Dozier in coordinating the atmospheric component of the various people in the group. global system. (ARM is the The contractors report to me, DOE's program of Atmospheric although they are available to Radiation Measurements.) assist in all areas of EOS. As Associate Director of the Earth The meeting will follow parallel Sciences Directorate, I am fa- meetings of the ARM science team miliar with most of the work and the CERES team at the same that is done at GSFC in the site. Workshop participants will Earth Sciences Field, and try to hear reports from representa- see that the correct people get tives of the various components the information needed to per- of the observing system and try, form their tasks. If you need through panel and informal assistance and do not know whom discussions, to arrive at new to call, contact me and I will ways to look at the system as a try to help with a minimum of while in answering the key redirection. The address is questions relating to the hydro- NASA/Goddard Space Flight Cen- energy cycle, air-sea interac- ter, Code 900, Greenbelt, MD tions, and general circulation. 20771, telephone (301) 286-8228, The goal of the workshop will be FAX (301) 286-3884, or DZUKOR on to produce documents which will GSFCMAIL. identify and elucidate to the atmospheric science community Dot Zukor the opportunities posed by the EOS Project Science new observing systems. Office Manager While the meeting has been ar- -------------------------------- ranged to take maximal advantage of participation of the teams WORKSHOP ON ATMOSPHERIC mentioned, all interested par- MEASUREMENTS ISSUES IN ties are welcome to participate. UNDERSTANDING CLIMATE CHANGE For further information contact: Gerlad R. North, Department of A workshop sponsored by the Meteorology, Texas A&M Universi- Department of Energy (DOE) and ty, College Station, TX 77802, NASA, and co-hosted by the Na- (409) 845-8083, OMNET:G.NORTH. tional Center for Atmospheric Members of the Executive Com- Research (NCAR), will be held mittee consist of Gerald North, Thursday and Friday, October 31 chair; Robert Cess, Robert and November 1, 1991, at the Dickinson, David Randall, Graeme Stapleton Plaza Hotel near the Stephens and Kevin Trenberth. airport in Denver, Colorado. The subject of the meeting will be utilization of the observing systems associated with ARM, Gerald North NASA Earth Probes, operational Panel Member EARTH OBSERVER Page 4 ___________________________________________________________________ MEETINGS_________________ detailed summary of two color ranging experiments in progress GLRS SCIENCE TEAM MEETING at GORF, including a discussion of streak camera characteris- The GLRS Science Team met at tics. He reported that prelimi- GSFC on May 14-15, 1991. Stan nary two-color ranging measure- Wilson and Jeff Dozier reported ments have been made to a ground on the EOS budgetary evolution target. Experiments to the and on the Engineering Panel Relay Mirror Experiment meeting chaired by E. Frieman. satellite will be attempted in They noted that some scenarios the next few weeks. of the B-series of instruments have included GLRS, ALT, and GGI Ken Brown (GSFC) reported that together. Bruce Guenther (GSFC) the GLRS contractors (GE and reported on the Calibration McDonnell-Douglas) have laser Panel meeting. breadboards of the instrument, which are expected to be in full Various studies are underway to operation within a few weeks. support GLRS development. Jim Brown and Bernard Seery (GSFC) Abshire (GSFC) reported on the reported on recent trips made to status of a study in progress on both contractors to review their effects of atmospheric turbu- status. lence. He reported that the development of a Sun workstation Tom Strikwerda, Applied Physics laser waveform simulator for the Laboratory, gave a summary of GLRS altimeter mode is near com- star trackers/cameras. He summa- pletion. rized satellite experiments in development and noted that the John McGarry (GSFC) summarized ultimate accuracy may be limited the status of the Wallops T-39 by the star catalog accuracy aircraft flights in support of (which will improve with Hippar- two-color ranging experiments. chos and Space Telescope). Cur- A total of eight flights is rent instrument operation at the planned around the Goddard Op- few arcsecond level has been tical Research Facility (GORF), demonstrated in ground-based with a flight path chosen to tests. Satellite experiments enable examination of azimuthal are scheduled. variations in range correction. Bob Schulz, University of Texas, Robert Thomas (HQ) reported that summarized the GLRS error the Greenland aircraft experi- budget, including the ments with a laser altimeter requirements for both attitude have been delayed until August and ephemeris. Consideration 1991. The aircraft flights will was given to both real-time and underfly selected ERS-1 post-processing requirements. groundtracks for direct compari- Details will be published in a son with another data set, in forthcoming report. addition to flight paths in other areas. Steven Cohen (GSFC) presented an update on geodetic simulations Thomas Zagwodksi (GSFC) gave a of the GLRS ranging component. EARTH OBSERVER Page 5 ____________________________________________________________________ These simulations include more Execution Phase proposals. The restrictive ground-based targets Science Management Plan is ex- and more representative error pected in the Fall. models. The next GLRS meeting will be The team extensively discussed held in the October-November preparation of a Science Manage- period. ment Plan and preparation of Bob Schutz GLRS Team Leader -------------------------------------------------------------------- EOS WORKING GROUPS MEET AT LANGLEY RESEARCH CENTER -------------------------------------------------------------------- A joint session of the EOS Mis- System Integration Manager, gave sion Operations Working Group an update of the ground system (EMOWG), the Ground System Inte- architecture, including the sci- gration Working Group (GSIWG), ence data processing function and the Science Operations Work- for the two EOS instruments ing Group (SOWG) was held at the (CERES and LIS) that fly on the Langley Research Center (LaRC) Tropical Rainfall Measuring Mis- in Hampton, VA, on June 25-27, sion (TRMM), and the NASA Sci- 1991. The EMOWG, GSIWG, and SOWG ence Internet (NSI) role within are working groups chartered the EOSDIS. under the EOS Ground System and Operations Project (GSOP) headed Sol Broder, Science Operations by Tom Taylor, GSFC Code 423. Manager (SOM), provided an in- troduction to the newly created Sidney Pauls, LaRC Associate SOWG. (Note: Since the meeting, Director, welcomed the attend- the SOWG has been renamed the ees. Tom Taylor, GSOP Project Data Processing Working Group Manager, discussed the current (DPWG) to be chaired jointly by status and schedule of Ground Sol Broder and Rich Bredeson, System activities, including the Science Software Manager.) EOS Data and Information System, Core System (ECS) procurement. The meeting featured presenta- (Note: The ECS Request For tions from the GSFC Project Sci- Proposal package was released on ence Office (provided by John schedule, on July 1, 1991.) Barker and Al Fleig), and pre- sentations on the following in- Angie Kelly, EOS Mission Opera- struments: Stick Scatterometer tions Manager (MOM), summarized (STIKSCAT) science overview, the meeting goals and the issues Mike Freilich, JPL; Lightning to be addressed by each of the Imaging Sensor (LIS), Hugh three working groups. Kelly also Christian, MSFC; Moderate Reso- restated the basic philosophy, lution Imaging Spectrometer "EOS Flies for Science." She (MODIS), John Barker; and Active then reviewed mission operations Cavity Radiometer Irradiance from a science team/user per- Monitor (ACRIM), Jim Kaufman, spective. Joe Gitelman, Ground JPL. An overview presentation on EARTH OBSERVER Page 6 ___________________________________________________________________ the Earth Observing Scanning strations of flight simulator Polarimeter (EOSP) was provided and data display/browse systems. by Larry Travis, Goddard Insti- tute for Space Studies, although Bill Weaver and Larry Brumfield, he was not able to attend. both with the LaRC CERES Pro- ject, coordinated the arrange- Other presentations dealt with ments for the meeting, which was mission operations and ground held in accordance with ECS pro- system topics: preliminary EOS- curement guidelines. Karen Mc- A1 nominal timeline, testing Donald, ECS Contracting Officer, concepts, Space Network Control was in attendance. Presentation Center update, NASCOM update, material from the meeting is international interfaces, Deep available at the GSFC EOS Li- Space Network operations con- brary. Call Heidi Wood, (301) cept, platform update/CCDS Prin- 286-5641. cipal Network and its opera- tional implications, and soft- The DPWG meets in October. Con- ware management and Tool-kits. tact Sol Broder (301) 286-7088 Splinter sessions dealt with or Rich Bredeson (301) 286-9338. science operations, testing, The schedule for the next EMOWG/ planning and scheduling, flight GSIWG meeting will be based on operations, prototyping plans, the ECS schedule. Contact: Angie realtime/quicklook data require- Kelly (301) 286-7726, Joe Gitel- ments, etc. Open issues regard- man, (301) 286-7055. ing instrument-to-ground-system interface were again discussed. Angie Kelly LaRC personnel provided demon- Mission Operations Manager -------------------------------------------------------------------- RELEASE OF EOS DATA PRODUCTS REPORT VERSION 1.0 -------------------------------------------------------------------- A report titled Earth Observing this information throughout the System Output Data Products and planning, implementation, and Input Requirements - Version 1.0 operational phases of the EOS- is being distributed to EOS DIS. Principal Investigators by the Science Processing Support Two earlier versions of the SPSO Office (SPSO) at GSCF. The SPSO documents were distributed for serves as a liaison between the review by the EOS investigators EOSDIS Project and the scientif- in August 1990 and April 1991. ic user community. It works in The current release is a revised cooperation with the EOS/EOSDIS and expanded version of the SPSO Project Scientists and the EOS report released in April 1991. investigators to compile, ana- The SPSO report, consisting of lyze, and review requirements Volumes I and II, presents the for science data processing. latest information on EOS output The SPSO also maintains and data products and input disseminates requirements infor- requirements for 30 EOS instru- mation and provides a single ments and 29 Interdisciplinary point-of-contact for access to Science (IDS) Investigators. It EARTH OBSERVER Page 7 ___________________________________________________________________ contains information on char- Four product-naming fields were acteristics of over 2400 EOS used to standardize product output and input data products names, group similar data and 200 non-EOS data sets re- products, and allow linkage to quired by EOS investigators. the Master Directory (MD) para- meter keywords used in Directory The report is based on the in- Interchange Format. formation compiled and synthe- sized by the SPSO since March A complete list of output and 1989. Information on EOS data input data products sorted by products was obtained from a product number is presented in number of sources. The "Silver Volume I of the SPSO report. Bullet" data product lists, com- Separate output data product piled by Vincent Salomonson (for lists for instrument teams and Facility Instruments), Jim Rus- IDS investigators are also sell (for Principal Investi- presented. In an effort to iden- gator Instruments), and JoBea tify unique EOS data products, Way (for Interdisciplinary In- similar data products are vestigators) were compiled and grouped together and a list of updated, based on the Phase C/D product group names, containing proposals, Conceptual Design and the corresponding MD parameter Cost Review presentations by keywords, is presented. Volume I instrument teams, and comments also describes the methodology from investigators. Information and assumptions used in the on MODIS-N/T data products and EOSDIS baseline requirement input requirements was provided analysis. In addition, the SPSO by the MODIS Science Processing analyses of storage require- Support Team managed by Al Fleig ments, processing load, and data of GSFC. Non-EOS input require- traffic flow estimates for EOS- ments, originally compiled from A1 instruments are presented. the Announcement of Opportunity proposals, were revised based on Volume II of the report is de- the SPSO input data surveys. voted to the SPSO analyses of IDS investigators' input re- A common format was adopted to quirements. For each investiga- enable cross comparison of In- tor, input requirements were terdisciplinary Investigators' analyzed and matching best/al- input requirements with proposed ternative EOS data products were output data products from EOS identified by comparing charac- instruments. The attributes of teristics of input and output the common format consist of data products. A best-match data those describing the measurement product is defined as an EOS (product name, units, and cate- data product that closely match- gory), source of information es input requirements in terms (type, source and investigator), of product definition, accuracy, characteristics of the data temporal resolution, and spatial product (resolution, coverage, resolution/coverage. An alterna- accuracy), and attributes that tive-match data product is a describe the input requirements product that meets the input (required channels, ancillary, requirements to a lesser degree. and correlative input data). Results of the analysis were EARTH OBSERVER Page 8 ___________________________________________________________________ presented in two separate appen- information becomes available. dices: one listed by IDS inves- tigator and the other by instru- The SPSO welcomes any comments ment. Volume II also contains from the scientific user commu- information on IDS investiga- nity on the report and wishes to tors' input requirements which express special appreciation to cannot be met by EOS instru- those who have provided valuable ments. suggestions for enhancements to this document. If you have any The analyses presented in the comments or would like to have a SPSO report are preliminary; copy of the SPSO report, please many details of the EOS project contact: Yun-Chi Lu, Code 936, will change over the course of NASA/GSFC, Greenbelt, MD 20771, the EOS mission. The SPSO at (301) 286-4093, YLU/GSFCMAIL. GSFC plans to release an updated version of the report on an an- Yun-Chi Lu nual or semi-annual basis as new SPSO Manager -------------------------------------------------------------------- CANADIAN ICE WORKING GROUP MEETS -------------------------------------------------------------------- Editor's Note: The Earth Ob- David Barber at the Earth Obser- server recently received a set vations Laboratory, ISTS, Uni- of summary charts elaborating versity of Waterloo, Ont, N2L the results of a meeting of 3G1. Telephone: 519-885-1211, the Canadian Ice Working Group ext. 2689. (CIWG) in Toronto, Canada on March 7, 1991. The meeting The object of the meeting was to was held at the Institute for establish the requirements for Space and Terrestrial Science information on cyrospheric (ISTS) Headquarters at York processes in the arctic marine University, Toronto, Ontario. eco-system that could be met by remote sending. The results of The paper is entitled "Science the meeting were then to be used Issues Relating to Marine As- as "design targets" in develop- pects of the Cryosphere: ment of follow-on proposals to Implications for Remote Sens- Canada's RADARSAT and in devel- ing." Co-authors of the paper opment of "SMALL-SAT" technolo- are David G. Barber, Michael gies within Canada by engineer- J. Manore, Thomas A. Agnew, ing companies participating in Harold Welch, Eric D. Soulis, the CIWG meeting. and Ellsworth F. LeDrew. With the permission of the authors, A long list of cryospheric we are summarizing the variables was developed and a thoughts presented in the science context was given for paper for the benefit of the each. Requirements for spatial Earth science remote-sensing and temporal resolution were community. Readers desiring given as well. ("Science con- more information may contact text" was simply explained as EARTH OBSERVER Page 9 ___________________________________________________________________ being "why" the measurement was ters required for measurement wanted.) The resulting collec- and monitoring of ocean-ice- tion of information ran 13 pages atmosphere related processes and so is not appropriate for in the arctic. We also con- presentation here, but a partial clude that remote sensing, in list of the variables is as fol- various regions of the elec- lows: ice concentrations, floe tromagnetic spectrum, can size, distribution, ice thick- provide useful information on ness, snow thickness, ice class- geophysical aspects of the es, snow density, ice surface perennial ice cover. The roughness, wind velocity, ice major difficulties/issues topography, temperature (air- which lie ahead include: ice-water interfaces), etc. * "Remote sensing surface Examples of "science context" in validation programs are the case of ice concentrations required to confirm the were: (1) ice strength for dyna- electromagnetic interac- mic models; penetrability for tions at a variety of fre- tactical navigation leading to a quencies and at various requirement for 10 m pixels and spatial and temporal reso- > 1 km swatch every six hours; lutions. (2) strategic navigation infor- mation requiring 1 km resolution * "Research is required to and six-hour to one-day repeats; determine the most effec- (3) marine mammal distributions tive means of using remote with a 10 m resolution lower sensing data in arctic sys- limit. tem models. The tables often contained "sum- * "An effective information mary notes" giving further in- system is a prerequisite to sight into the need to have the establishing a broad, pro- variables measured in the manner ductive user base of arctic specified. For example, the sum- remote sensing data. Non- mary notes for ice concentra- remote sensing specialists, tions read that "ice concentra- who are experts in their tion is an important variable particular arctic research, for most ocean-ice-atmosphere- should be consulted when related research ... Small floes establishing this system. (about 100 m^2) are used as walrus haulouts. Larger scale * "Catastrophic events (and concentrations may determine 'good' years) often drive whale and seal distributions." success and failure of arctic populations, more so The authors' conclusions are than at lower latitudes. presented verbatim below: The utility of temporal records is considerable and "Although neither inclusive should be thoroughly evalu- nor exhaustive we believe our ated in hindcasting and list of cryospheric variables forecasting studies of arc- represents a good overview of tic processes. We consider the type and range of parame- EARTH OBSERVER Page 10 ___________________________________________________________________ temporal scales of interan- data sets for some applica- nual to inter-decadel im- tions may be prohibitive if portant within the context a philosophy of cost recov- of this exercise. ery is implemented across all research disciplines. * "Many of the variables are In particular, inter-annual highly interrelated. We analyses will become pro- have not attempted to sep- hibitive given current arate out uniqueness or research funding levels. redundancy in our assess- The assessment of a general ment of the science objec- public good within various tives. Efforts will be research categories must be required to prioritize and assessed and the funding more objectively assess the levels set accordingly." complementary nature of the numerous variables re- The full results of the CIWG quired. meeting will be published in a forthcoming issue of the Canadi- * "We have devised the sci- an Journal of Remote Sensing. A ence objectives independent follow-on CIWG meeting, where of our working knowledge of design considerations will be what is currently available emphasized, is currently sched- from remote sensing. These uled for October in Halifax, objectives represent opti- Nova Scotia. mal conditions, and should be revisited as advances in Meeting attendees were: Tom remote sensing technology Agnew, Dave Barber, Ric Cox, arise. Greg Crocker, Ben Danielewicz, Ellsworth LeDrew, Marion Lewis, * "Development of future sen- Chuck Livingstone, Anthony sor technologies must con- Luscombe, George MacFarlane, tinue to be done in close Mike Manore, Marie-Jose Montpe- coordination with the vari- tit, Ven Neralla, Bruce Ramsay, able types, ranges, preci- Irene Rubenstein, Mohamed Sayed, sions and accuracies by Ric Soulis, Ian Stirling, arctic researchers. Charles Tang, Ken Tanner, Buster Welch, and Harold Zwick. Writ- * "Costs associated with ten contributions: Simon Prin- obtaining remote sensing senburg and Pierre Richard. EARTH OBSERVER Page 11 ____________________________________________________________________ -------------------------------------------------------------------- UPPER ATMOSPHERE RESEARCH SATELLITE -------------------------------------------------------------------- Here are excerpts of remarks made by Robert J. McNeal, UARS Program Scientist, at a UARS press briefing on August 15, 1991. UARS is of special interest to our Earthing Observing community as a predeces- sor to EOS. "On September 12, NASA will ozone depletion will be great launch the Upper Atmosphere value to policymakers in dealing Research Satellite (UARS) and with the complex ozone depletion begin a new era of study of the problem. UARS will provide the global environment... We must global data base for those deal with a whole new class of improved models In so doing, it environmental problems where the will contribute directly to arena is the entire planet; the understanding of a critical en- time required for solutions can vironmental problem, and it will span several human generations; lead to a tremendous increase in and the costs of corrective our knowledge of what is essen- actions can be enormous. tially a new frontier in ex- perimental space science -- our "Development of strategies for own Earth's upper atmosphere. solving these problems requires global data sets on the Earth as "UARS will be by far the largest a system that can only be col- satellite ever flown for atmos- lected from space. In response pheric research. The payload to this need, NASA has designed consists of 10 instruments, Mission to Planet Earth, a long which make their measurements term, multi-satellite program to independently but make up essen- study our own planet from space tially a single large and well and gather the needed data. integrated experiment to study atmospheric chemistry, dynamics, "UARS is the first satellite in and energy inputs... that program. It will observe the Earth's upper atmosphere "The chemical composition meas- with a focus on the strato- urements of UARS will provide us sphere, the location of the with pictures very much like Earth's protective ozone layer. those [from TOMS] but resolved Concern about the depletion of in altitude. We will see the this layer by manmade chloroflu- three-dimensional structure of rocarbons (CFCs) has risen the ozone model, and (in fact) sharply in the last few years ozone around the globe. We will with the appearance of the also have three-dimensional maps Antarctic ozone hole and new of the chemical species that evidence from trends analysis control ozone concentration and for a 5% depletion of ozone at of the wind fields that move mid-latitudes during the last ozone around. We will also have decade... simultaneous data on the solar and energetic particle inputs "Clearly, improved models of that are the drivers for all EARTH OBSERVER Page 12 ___________________________________________________________________ atmospheric processes. available for early public release in view of extraordinary "The UARS program has recognized public interest in stratospheric from its beginning the great ozone depletion. importance of timely data analy- sis and theoretical studies. "A large correlative measure- Ten theoretical principal inves- ments program will be carried tigators were selected at the out along with UARS and will same time as the nine experi- include ground-based instru- ments. In addition, many of the ments. There will be cooperat- instrument teams have theoreti- ing, major U.S. and European cal co-investigators. Plans are aircraft and balloon campaigns in place for very rapid data during the winter of 1991-1992 analysis. All of the data will aimed at detailed process stud- be accessible, as soon as it is ies of arctic ozone to look for processed, to the entire team. indications of large ozone depletion like that seen in the "Key data products will be Antarctic." ------------------------------------------------------------------- LETTERS TO THE EDITOR ------------------------------------------------------------------- To the Editor: take the opportunity to point out the characteristics of the We read with interest your ac- SCIAMACHY instrument that are count of the March 26-27, 1991 relevant to such comparisons. SAGE III team meeting in Vol.3, The SCIAMACHY spectral range No.4 of The Earth Observer. We includes, in addition to were puzzled to see that, in continuous wavelength coverage comparison with GOMOS, GOME, from 240 to 1700 nm, two short- SCIAMACHY, and ILAS, it was wave infrared bands in the SWIR concluded that "SAGE III will be at 1940-2440 nm and 2256-2380 the only instrument capable of nm. SCIAMACHY measurements are characterizing aerosols below 20 made at moderately high spectral km, and the only one of these resolution (0.2 to 1.4 nm), with instruments that can provide a spatial resolution correspond- vertical profile data (of impor- ing to 1.2 km at the earth's tant gases) to at least mid- limb. It can thus match the troposphere." range of both gas and aerosol measurements made by SAGE III As investigators on SCIAMACHY below 20 km. (and GOME) we wish to point out that SCIAMACHY, in its In the troposphere there is a occultation mode, is at least relatively high probability equally capable of making such that, in the occultation measurements. As we were not geometry below 15 km, clouds may present at the SAGE III team obstruct the view. Therefore, meeting, we have no way of in our studies of the accuracy knowing how the above conclu- of parameter retrieval from sions were obtained, but wish to SCIAMACHY measurements in the EARTH OBSERVER Page 13 ___________________________________________________________________ occultation geometry, our pro- The Earth Observer, Volume 3, nouncements were restricted to No. 4, regarding SCIAMACHY's 15 km and above. The intention capability to measure aerosols to retrieve trace gas and aero- and gases below 20 km in solar sol abundances from tangent occultation. Based on your pre- heights below 15 km in the sentations and other materials absence of obstruction by cloud on SCIAMACHY, it is our under- measurements was, however, standing that your horizontal expressed. We are pleased to (left-right) field-of-view is or find that the SAGE III team has the order of 2 degrees. Because concluded that measurements of this large field-of-view, we below 15 km are indeed possible. feel your attenuation measure- ments will have a strong aerosol It is planned to launch forward scattering component SCIAMACHY on the European Space contained within them which will Agency's POEM-1 platform. POEM-1 make interpretation very diffi- has a planned polar orbit, so cult. Heavy aerosol loading and that global coverage in clouds will further exacerbate occultation will be comparable interpretation. In addition, the to NASA's polar-orbiting plat- large field-of-view will greatly forms (SCIAMACHY is also under lower the probability of tropo- study for German and French spheric penetration. SAM II and polar-orbiting atmospheric SAGE I have circular fields-of- satellites, providing this view of approximately 0.5 arc coverage at an earler time-frame min, while SAGE II's field-of- than that planned for EOS-B and view is 0.5 arc min vertically POEM-1). by 2.5 arc min horizontally. It is this small field-of-view that Sincerely yours, allows a high probablity of tropospheric penetration. Dr. Kelly Chance Harvard-Smithsonian Ctr for I will be happy to discuss this Astrophysics with you, or to provide any of our SAM II and SAGE experiences which will help in your design Dr. John P. Burrow of SCIAMACHY. Atmospheric Chemistry Division, Max Planck Institute for Chemistry M.P. McCormick Principal Investigator, SAGE III ------------------------------- Dear Kelly and John: This letter is in response to your July 24, 1991 letter to the Editor of The Earth Observer, and to give you directly the reasons for the statements in EARTH OBSERVER Page 14 ____________________________________________________________________ THE EARTH OBSERVER The Earth Observer is published by the EOS Project Science Office, Code 900, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, telephone (301) 286-3411, FAX (301) 286-3884. Correspondence may be directed to Charlotte Griner at the above address. Articles, con- tributions to the meeting calendar, and suggestions are welcome. Contributions to the meeting calendar should contain location, person to contact, and telephone number. Deadline for all submis- sions is the 20th of each month. To subscribe to The Earth Observer, or to change your mailing address, please call (301) 513-1613, or write to the address above.