Eos, Vol. 68, No. 2, January 13, 1987

Rep. 4, Bur. Gravimetrique Int., Toulouse, data, terrestrial gravity and other data, Rep. Bernard Moynot re­ France, 1982. 322, Dep. of Geodetic Sci. and Surveying, ceived his degree in mathe­ Balmino, G., C. Brossier, A. Cazenave, and F. Ohio State Univ., Columbus, 1982. matics from the Ecole Nor­ Nouel, Geoid of the Kerguelen Islands area Rapp, R. H., The determination of geoid un­ male Superieure of Paris determined from GEOS 3 Altimeter data, dulations and gravity anomalies from Sea­ in 1963. In 1956, he be­ /. Geophys. Res., 84, 3827, 1979. sat altimeter data,/ Geophys. Res., 88, 1552, gan working with the Cen­ Cazenave, A., B. Lago, and K. Dominh, 1983a. tre National d'Etudes Spa­ Thermal parameters of the oceanic litho- Rapp, R. H., The development of the Janu­ tiales, performing research sphere estimated from geoid height data, J. ary 1983 1° x 1° mean free-air anomaly in satellite geodesy and nu­ Geophys. Res., 88, 1105, 1983. data tape, internal report, Dept. of Geodet­ merical analysis. He is now Haxby, W. F., G. D. Karner, J. F. Labrecque, ic Sci. and Surveying, Ohio State Univ., Co­ with the Bureau Gravime­ and J. K. Weissel, Digital images of com­ lumbus, 1983ft. trique International in Toulouse. bined oceanic and continental data sets and Reigber, C, H. Muller, W. Bosch, G. Bal­ Michel Sarrailh gradu­ their use in tectonic studies, Eos Trans. mino, and B. Moynot, GRIM gravity model ated from the Institut de AGU, 64, 995, 1983. improvement using LAGEOS (GRIM 3- Physique du Globe in Lazarewicz, A. R., and D. C. Schwank, Detec­ L1)J. Geophys. Res., 90, 9285, 1985. Strasbourg, France, and tion of uncharted seamounts using satellite Torge, W., G. Weber, and H. G. Wenzel, received an engineering de­ altimeter data, Geophys. Res. Lett., 9, 385, High-resolution gravimetric geoid heights gree in geophysics in 1971. 1982. and gravimetric vertical deflections of Eu­ After working for 2 years Lerch, F. J., B. H. Putney, C. A. Wagner, and rope including marine areas, Mar. Geophys. with the SAP A Geophysical S. M. Klosko, Goddard earth models for Res., 7, 447, 1984. Company, he taught geo­ oceanographic applications (GEM 10B and physics at the Institut Al- 10C), Mar. Geodesy, 5, 145, 1981. gerien du Petrole (Algeria) Levitus, S., Climatological Atlas of the World and then joined the Paris Institut de Physique du Ocean, NOAA Prof. Publ. 13, Geophys. Flu­ Globe in 1978. Since 1980, Sarrailh has been id Dyn. Lab., Princeton, N.J., 1982. Georges Balmino working with the Bureau Gravimetrique Interna­ Marsh, J. G., and T. V. Martin, The Seasat graduated from the Ecole tional in Toulouse. altimeter mean sea surface model, J. Normale Superieure of St. Geophys. Res., 87, 3269, 1982. Cloud and then received a Nicole Vales received Marsh, J. G., A. Brenner, B. D. Beckley, and master's degree in mathe­ degrees in physics and T. V. Martin, Global mean sea surface matics and a Ph.D. in chemistry from Toulouse computation using GEOS 3 altimeter data, physics (in 1973) from University in 1972. She J. Geophys. Res., 87, 955, 1982. Paris University. After sev­ then worked in computer Marsh, J. G., R. E. Cheney, J. J. McCarthy, eral years with the Meudon sciences at Informatique and T. V. Martin, Regional mean sea sur­ Astronomical Observatory, Internationale. Since faces based upon GEOS 3 and Seasat altim­ he joined the Centre Na­ 1981, she has been with eter data, Mar. Geodesy, 8, 385, 1984. tional d'Etudes Spatiales in Toulouse (1974), the Centre National d'E­ Rapp, R. H., Global anomaly and undulation where he led the French part of the team involved tudes Spatiales. Vales is in­ recovery using GEOS 3 altimeter data, OSU in the Franco-German GRIM geopotential models. volved with earth and Rep. 285, Dep. of Geodetic Sci. and Survey­ Balmino has been director of the Bureau Gravime­ planetary science computations at the Groupe de ing, Ohio State Univ., Columbus, 1979. trique International since 1980. His current re­ Recherches de Giodisie Spatiale, a department of Rapp, R. H., The earth gravity field to de­ search interests involve celestial mechanics, satellite the Centre National d'Etudes Spatiales that hosts gree and order 180 using Seasat altimeter geodesy, and planetology. the Bureau Gravimetrique International.

ment and deployment activities, coupled with related theoretical modeling work using a CEDAR: fully coordinated approach to a series of ma­ jor outstanding scientific questions. The sec­ ond volume, in two parts, contains the collat­ An Aeronomy Initiative ed reports from the seven subcommittees charged with the specific areas of theoretical modeling, spectroscopy, interferometry, im­ PAGES 19-21 aging, LIDAR, ionospheric/thermospheric ra­

1 2 3 dar, and lower-thermospheric/mesospheric G.J. Romick, T. L. Killeen, D. G. Torr, radar. 4 5 5 The CEDAR plan is in response to the call B. A. Tinsley, * and R. A. Behnke from the National Academy of Sciences for a National Solar-Terrestrial Research Program, Introduction outlining a comprehensive 7-year plan for the or NSTP (see the report "National Solar-Ter­ ground-based study of the earth's upper at­ restrial Research Program" by the Committee A 3-year process of committee delibera­ mosphere. The two-volume report, entitled on Solar Terrestrial Research, National Acad­ tions and community-wide annual workshops "CEDAR: Coupling, Energetics, and Dynam­ emy of Sciences, Washington, D.C, 1984). by scientists involved in aeronomical studies ics of the Atmospheric Regions," was assem­ NSTP, as defined by the academy, incorpo­ has led recently to the presentation of a final bled under the aegis of the Aeronomy Pro­ rates three elements: a spaceborne compo­ report to the National Science Foundation, gram of NSF and involved the efforts of a nent, a theory and data analysis program, team of 66 active researchers from 32 U.S. and a strong program of ground-based ex­ 1Geophysical Institute, University of Alas­ and Canadian institutes. The volumes, taken perimental studies. CEDAR represents an im­ ka, Fairbanks together, contain a review of the present state portant contribution to the latter two NSTP 2Space Physics Research Laboratory, Uni­ of the art in current and projected experi­ elements, as it provides a link and a comple­ versity of Michigan, Ann Arbor mental and theoretical capabilities for the ment to the upcoming NASA Upper Atmo­ department of Physics, University of Ala­ field, ranging from the middle atmosphere sphere Research Satellite (UARS) and the In­ bama at Huntsville (mesosphere) through the thermosphere and ternational Solar Terrestrial Program (ISTP), 4Center for Space Sciences, University of ionosphere and into the exosphere and pro- whose national component has been recently Texas at Dallas, Richardson tonosphere of the earth. The first volume relabelled the Global Geospace System (GGS). 5Division of Atmospheric Sciences, National contains the scientific rationale for a program The initial impetus for the CEDAR effort Science Foundation, Washington, D.C. of careful, measured instrumental develop­ came from a general realization that the in-

0096-3941/87/6802-19$ 1.00 Copyright 1987 by the American Geophysical Union Eos, Vol. 68, No. 2, January 13, 1987

whole, including, for example, the effects of 5 SEC. • energy, momentum, and compositional inter­ change between regions. To meet this chal­ lenge will require not only new and improved instruments but will also necessitate global- 1970S TECHNOLOGY scale coverage of many parameters, as well as measurements of the critical parameters re­ lated to the important couplings between at­ mospheric regions. Such measurements will POST 1980 TECHNOLOGY require coordination and collaboration among experimentalists and between experi­ mentalists and theoreticians. They will also require a pooling and common use of data collected from networks of observatories and facilities. The process of reviewing both the theoreti­ cal and experimental status of aeronomy by the CEDAR subcommittees and the develop­ ment of a 7-year program plan representing the consensus view of the U.S. Aeronomy Community lasted 3 years. During this peri­ od, well-attended annual summer workshops were held (at Utah State University, Logan, in 1983; at the University of Michigan, Ann 4000 4400 4800 5200 5600 6000 6400 6800 7200 7600 8000 Arbor, in 1984; at the University of Seattle, WAVELENGTH (ANGSTROMS) Seattle, Wash., in 1985; and at the High Alti­ tude Observatory of the National Center for Atmospheric Research (NCAR), Boulder, 5 SECONDS ^ Colo., in 1986) to ensure the full participa­ Fig. 1. Illustration of the great improvement in data-taking ability of high-resolution tion of the broad community. Focused steer­ spectrometers afforded by modern technology. Rapid coverage of an extensive spectral re­ ing committee and subcommittee meetings gion is required for many problems in quantitative atmospheric spectroscopy. Similar, dra­ were also conducted at more frequent inter­ matic improvements in the capabilities of the various optical and radar instruments used in vals. aeronomical studies are possible by using existing technology and will provide significant This relatively lengthy review process has observational benefits over a broad range of scientific topics in atmospheric physics and already created a new atmosphere of cooper­ chemistry. ation and collaboration within the aeronomy community, cooperation that is paying off in terms of significant collaborative projects. strumental techniques deployed in aeronomi­ execution of many future aeronomical stud­ Furthermore, the many workshops and the cal field campaigns used technology that was ies. This last requirement represents a signifi­ increasingly intensive interaction between at­ 2 decades old. Experimentalists were con­ cant change in approach for a scientific com­ mospheric scientists with closely related and cerned that existing modern designs and munity nurtured on the idea of single investi­ complementary interests has led to a spirit of techniques were not being used to benefit gators contributing first-rate science from collegiality that bodes well for the future ground-based aeronomy. The concern was individual observatories. While this undoubt­ health and vitality of the field. founded on the fact that aeronomy is, in gen­ edly remains true in certain cases, many of eral, a "signal-limited" science in that the sen­ the major outstanding scientific issues call In the following sections, we provide a sitivity of the various instruments (radar, clearly for a coordinated multistation, multi- brief summary of the scientific rationale and photometers, spectrometers, imagers, inter­ instrument approach. The reason for the the program plan for CEDAR as laid out in ferometers, LIDAR, etc.) limits the number change in emphasis is related to the recent the report to NSF. Interested readers can ob­ of feasible experiments and introduces tanta­ development of our understanding of the tain copies of both volumes of the report lizing uncertainties in interpretations because near-space environment. Previous national from the authors (contact G. J. Romick, Geo­ of poor statistics. As a simple but telling ex­ research efforts have focused on individual physical Institute, University of Alaska, Fair­ ample of the utility of more modern technol­ regions of the solar terrestrial system. For ex­ banks, AK 99701). ogy for aeronomy, Figure 1 illustrates the ample, the NSF incoherent scatter radar vast improvement in speed of spectrometer chain has concentrated on the study of the Scientific Rationale systems based on modern (charge-coupled ionosphere and thermosphere, the Solar-Me- for CEDAR device, or CCD) technology over those using sosphere Explorer (SME) satellite on the me- more traditional single-channel phototubes. sosphere, the Atmosphere Explorer series on Aeronomy is the study of the earth's upper The speed and spectral range covered by the photochemistry of the thermosphere and atmosphere and of the physical, chemical, such instruments can be critical for success­ ionosphere, the International Sun-Earth Ex­ and plasma processes that modulate and par­ fully attacking many problems in quantitative plorer (ISEE) series on the magnetosphere tition the flow of solar energy through our atmospheric spectroscopy. Another example and interplanetary system, the Solar Maxi­ near-space environment. The scientifc objec­ from the radar field would be the high-speed mum Mission (SMM) on the sun, and the tives for CEDAR include the study of a broad digital signal processing currently available Dynamics Explorer twin spacecraft on the range of problems related to the physics that for the acquisition of real-time data. dynamics and electrodynamics of the thermo­ couples atmospheric regions. The cover of From these initial experimental concerns, sphere. Spurred by these programs, relatively this issue is a schematic illustration of some of however, the scope of the CEDAR study was mature models of individual components of the interesting phenomena that occur in the broadened as a full scientific rationale was the solar-terrestrial environment exist. These altitude range covered under the initiative, as sought to justify proposed experimental de­ include global (or global-scale) models of the well as some of the ground-based techniques velopment and the use of powerful modern troposphere, stratosphere, mesosphere, ther­ that can be used profitably to study these and but relatively expensive technology. The en­ mosphere, ionosphere, exosphere, plamas- other phenomena. suing thorough scientific review of aeronomy phere, magnetosphere, interplanetary medi­ The earth's upper atmosphere is constantly from the middle atmosphere through the um, and the sun. undergoing periodic and aperiodic changes. thermosphere and ionosphere to the exo- Today, the major questions posed relate to These changes are induced by solar energy sphere provided the justification for improve­ the interactions between regions: Interactions entering the atmosphere, both directly as ments in instrumentation but also pointed, that-are currently only crudely understood. electromagnetic radiation and indirectly perhaps more fundamentally, to a clear re­ Thus the principal scientific challenge before through magnetospheric convection and par­ quirement for community-wide and even in­ aeronomy is to understand the coupled atmo­ ticle precipitation. The latter energy is impul­ ternational coordination in the planning and spheric regions on a global scale and as a sively released in ways that depend on the de- Eos, Vol. 68, No. 2, January 13, 1987

volume of the CEDAR report itemizes the specific science topics for study and recom­ mends a phased approach (discussed below) as a method of systematic investigation that would take advantage of the projected instru­ mental and modeling developments over the next few years. Readers are referred to the two-volume CEDAR report for further de­ tails concerning the individual topic-related scientific objectives and program implementa­ tion strategy.

Phasing Strategy and Management Plan

The approach recommends a coordinated program of research and sequential steps leading to the development and deployment of new instrumentation, involving both im­ proved versions of present types and 1990 state-of-the-art facilities. The plan involves three phases of implementation designed to match growth in hardware and modeling de­ velopment with budgetary resources. A find­ ing of interest that emerged from the studies was the rapid increase in the number of trac­ table science problems that could be ad­ 180 160 140 120 100 80 60 40 20 0 20 40 60 80 100 120 140 160 180 dressed with the evolving complement of new • IS RADAR »FPI and improved instruments. Fig. 2. Worldwide distribution of incoherent scatter (IS) radar facilities and Fabry-Perot In Phase 1, which has already begun, utili­ interferometer (FPI) observatories, indicating present capabilities for coordinated measure­ zation of the existing inventory of instru­ ments with, for example, the "pole-to-pole" longitudinal chain enclosed by the dotted line. ments will be optimized by introducing coor­ dinated observational programs designed to provide data bases that would otherwise not tails of how the interplanetary magnetic field or coupling between the various atmospheric exist. This significantly increases the number merges with the geomagnetic field. This regions. The CEDAR program is commited of scientific topics that can be addressed. For process generates complex and variable elec­ to utilizing the existing data from satellites, example, one of the first coordinated pro­ tric potentials and currents that, in turn, re­ rockets, radars, and optical instruments, to­ grams defined in the CEDAR report will pro­ sult in large insertions of electrical and cor­ gether with data from the recommended new vide the data needed to define the mean puscular energy to the upper atmosphere. program of ground-based measurements, to characteristic behavior of global thermo- The consequences of this variable energy in­ study the coupled near-earth environment as spheric winds and temperatures, as well as to put are felt across the globe and are mani­ a whole. quantify departures from the mean. Initial fested by changed in ionization, excitation, The missing elements of the current obser­ campaign activities to accomplish this objec­ heating, dynamical behavior, composition, vational base are simultaneous measurements, tive were carried out during winter 1985— and thermal structure. on a global scale, of key parameters relevant 1986 from a number of optical and radar fa­ In addition, thermal and orographic effects to coupling throughout the solar terrestrial cilities (indicated in Figure 2). A second pro­ initiated at low altitudes influence the upper system. The program plan for CEDAR rec­ gram addressed the global-scale morphology atmosphere. These effects force the general ommends the establishment of a number of of mesopause temperatures from a similar circulation and create wave motions of all strategically located observatories with a syn­ global network of optical facilities. A third co­ kinds (tidal, planetary, and internal gravity). ergistic complement of instrumentation, in­ ordinated program is providing a data base Many of the associated aeronomic process­ cluding combinations of the following instru­ on both auroral latitude and low-latitude en­ es leave some atmospheric constituents in ex­ ments: ergy and momentum inputs, together with in­ cited states, and their excess energy is partial­ • more sensitive spectrometers, interferom­ formation on waves and dynamical perturba­ ly shed through visible and near-infrared eters, and imagers; tions in the upper atmosphere. In the latter emissions at specific wavelengths. Ground- • upgraded existing large radars; and program, as throughout the recommended CEDAR activities, the most appropriate com­ based measurements of these emissions pro­ • new and upgraded LIDAR and small ra­ bination of optical and radar ground-based vide direct information on the composition of dar systems. the atmosphere, on its dynamical and ther- facilities will be used. The plan allows for a much-improved cover­ modynamical state, and on various physical age of the essential observables required for In Phase 2, existing instruments will be up­ and chemical processes that occur. These the study of coupling processes. A fundamen­ graded, and additional observing stations will emissions originate from the entire altitude tal aspect of the program will be the coordi­ be established to fill out the global grid, ex­ range of interest, encompassing the tropo­ nation of activities, with carefully considered panding the capability towards fuller studies sphere, stratosphere, mesosphere, thermo­ instrument development, deployment, and of global-scale coupling. This activity will ap­ sphere, ionosphere, and magnetosphere. In data handling strategies. proximately triple the number of scientific addition to the use of optical emissions as a topics that can be addressed, adding, for ex­ Three broad categories embrace the scien­ diagnostic of upper atmosphere processes, ac­ ample, studies of the effects of ring current tific goals of the CEDAR program: tive sounding techniques employing powerful energetic particle precipitation, studies of radars and LIDARs are able to measure • Dynamics and energetics of the upper at­ exospheric hydrogen, and studies of thermo- many of the important parameters directly as mosphere from the mesopause upward to spheric composition, dynamics, and energet­ a function of altitude. the exobase, with particular emphasis on ics for various geophysical conditions. The As mentioned above, relatively mature the­ the hard to observe region between 80 same instrument complement will provide oretical models of individual components of and 150 km. data on dynamics, composition, and tempera­ the solar terrestrial environment exist. These • Ionospheric-thermospheric-exospheric- tures of the mesosphere, establishing the ini­ models can be effectively constrained and magnetospheric coupling. tial framework for studying the coupled ther- thereby improved by using ground-based ob­ • Mesospheric-thermospheric coupling. mosphere/mesosphere system. At the same servations. For atmospheric models the major Within these categories are many scientific time, improved measurements of auroral questions now posed relate to the interactions topics that require detailed study. The first processes will be acquired, including the spec- Eos, Vol. 68, No. 2, January 13, 1987 troscopy of emissions relevant to many atomic Science Steering Committee, impanelled by physics at the University of Alaska. His principal and molecular processes and the observations the NSF Aeronomy Program, will provide sci­ scientific interests include detailed studies of the au­ of electron densities and temperatures with entific guidance through the various CEDAR rora, including coordinated satellite, rocket, and sufficiently high altitude and time resolution. phases. With suitable additions to technical ground-based spectroscopic measurements of the al- This increase in available high-quality in­ and scientific staff, NCAR will assume re­ titudinal structure. Romick serves as the chairman formation will be accompanied by the devel­ sponsibility for archiving and providing ac­ of the NSF CEDAR Science Steering Committee. opment of advanced modeling capabilities cess to the large data bases. Timothy L. Killeen received his Ph.D. from and the holding of coordinated workshops University College London in 1975. He is current­ designed to address specific topics. Recent Summary ly an associate research scientist in the Space Phys­ models for successful topic-related workshops ics Research Laboratory of the University of Michi­ include the coordinated incoherent scatter ra­ The CEDAR program was developed over gan. Killeen's principal scientific interest is in the dar Global Incoherent Scatter Monitoring of a 3-year period of workshops, science sympo­ dynamics of the upper atmosphere. He serves on the Substorms (GISMOS) study and the Global sia, and committee deliberations. It attempts National Academy of Sciences (NAS) Committee Thermospheric Mapping Study (GTMS). to provide a realistic framework for the de­ for Solar-Terrestrial Research, is an associate edi­ Phase 3 realizes the full potential of the velopment of upper atmospheric research in tor of the Journal of Geophysical Research- CEDAR program, in which the maximum the United States through an evolutionary Space Physics, and is currently serving as secre­ number of scientific topics will be addressed. strategy of instrument development and de­ tary of the AGU Aeronomy Section. With the establishment of the advanced tech­ ployment activities designed to meet the chal­ nology "Class 1" facilities, deployed at six to lenge of a set of important scientific topics re­ Brian Tinsley has begun a 2-year term as pro­ eight strategically-located sites, the science lated to the study of the global-scale coupled gram director for aeronomy at NSF. He is a pro­ potential rapidly increases. In addition to the near-earth environment. The potential con­ fessor of physics at the University of Texas at Dal­ topics already mentioned, some examples of tribution of CEDAR studies to the national las and has been involved in observational and the­ the new science to be addressed include stud­ effort in solar-terrestrial research is great. oretical studies of geocoronal hydrogen and of low- ies of E region transport, including feedback There has already been substantial interest latitude aurora, as well as in the imaging of from the thermosphere to the magneto­ shown in CEDAR by our international col­ transequatorial ionospheric bubbles. He served as sphere; observations of the tides in the meso­ leagues, and it is to be anticipated that the chairman of the International Association of Geo­ sphere and their propagation to the thermo­ collaborative approach adopted by the U.S. magnetism and Aeronomy Division II during sphere; and studies of the mesospheric and aeronomy community will extend to include 1973-1979. lower thermospheric gravity wave momentum various other national groups and organiza­ and turbulence budgets. Simultaneous tions. In order to minimize costs for the pro­ Richard Behnke received his Ph.D. in space LIDAR and rocket measurements will pro­ gram, the program planners envision gradual science and aeronomy from Rice University in vide data on the variability of the mesospher­ growth over several years, optimizing the sci­ 1970. From that time until 1982, he worked at the ic eddy diffusion coefficient, together with entific usage of existing capabilities and National Astronomy and Ionosphere Center in Are- detailed information on the concentrations of stressing the gains to be made by adopting a cibo, Puerto Rico, where he studied the motions of ions and neutrals and on temperatures, as coordinated approach to the study of the the earth's upper atmosphere. Since 1982, he has well as on dust and noctilucent clouds. Coor­ earth's upper atmosphere. been program manager for upper atmosphere facili­ dinated observations of the above type will ties at NSF. provide a unique opportunity for studies of Acknowledgments Douglas Torr received his Ph.D. in ionospheric coupling between the regions of the upper at­ physics from Rhodes University in South Africa. mosphere. The plan for this final phase of The CEDAR study was conducted under He is currently a professor of physics at the Univer­ CEDAR includes full-scale integration of sev­ the auspices of the NSF Aeronomy Program. sity of Alabama, Huntsville. While Torr has spe­ eral instruments per observatory, all with co­ Individuals from many institutes have made cialized in thermospheric photochemistry, his inter­ ordinated data acquisition, processing, and important contributions to the effort. A full ests range from magnetosphere-ionosphere coupling rapid communal access to data, as well as to list of the CEDAR committee and subcommit­ to the chemistry and dynamics of the stratosphere, the predictions of relevant theoretical models. tee membership can be found in volume 1 of mesosphere, and thermosphere. He has served as A critical step in developing the group of the report. editor of Geophysical Research Letters and on Class 1 facilities involves their operation and committees such as the NAS Committee on Solar management. The NSF Upper Atmosphere Gerald Romick received his Ph.D. from the and Space Physics and various NASA and NSF Facilities Program already provides an estab­ Geophysical Institute of the University of Alaska in committees, including the NSF CEDAR steering lished vehicle for this activity. The CEDAR 1964. He is currently an emeritus professor of geo­ and modeling committees.