The NASA Upper Atmosphere Research Program organized a Stratospheric Ozone Intercomparison Campaign (STOIC) held in July–August 1989 at the Table Mountain Facility (TMF) of the Jet Propulsion Laboratory (JPL). The primary instruments participating in this campaign were several that had been developed by NASA for the Network for the Detection of Stratospheric Change: the JPL ozone lidar at TMF, the Goddard Space Flight Center trailer‐mounted ozone lidar which was moved to TMF for this comparison, and the Millitech/LaRC microwave radiometer. To assess the performance of these new instruments, a validation/intercomparison campaign was undertaken using established techniques: balloon ozonesondes launched by personnel from the Wallops Flight Facility and from NOAA Geophysical Monitoring for Climate Change (GMCC) (now Climate Monitoring and Diagnostics Laboratory), a NOAA GMCC Dobson spectrophotometer, and a Brewer spectrometer from the Atmospheric Environment Service of Canada, both being used for column as well as Umkehr profile retrievals. All of these instruments were located at TMF and measurements were made as close together in time as possible to minimize atmospheric variability as a factor in the comparisons. Daytime rocket measurements of ozone were made by Wallops Flight Facility personnel using ROCOZ‐A instruments launched from San Nicholas Island. The entire campaign was conducted as a blind intercomparison, with the investigators not seeing each others data until all data had been submitted to a referee and archived at the end of the 2‐week period (July 20 to August 2, 1989). Satellite data were also obtained from the Stratospheric Aerosol and Gas Experiment (SAGE II) aboard the Earth Radiation Budget Satellite and the total ozone mapping spectrometer (TOMS) aboard Nimbus 7. An examination of the data has found excellent agreement among the techniques, especially in the 20‐ to 40‐km range. As expected, there was little atmospheric variability during the intercomparison, allowing for detailed statistical comparisons at a high level of precision. This overview paper will summarize the campaign and provide a “road map” to subsequent papers in this issue by the individual instrument teams which will present more detailed analysis of the data and conclusions.

A series of coordinated atmospheric ozone profile measurements was made during October and November 1988. The instruments making observations and their locations were as follows. The Jet Propulsion Laboratory (JPL) and Goddard Space Flight Center differential absorption lidar systems were located at the JPL‐Table Mountain Facility 34.4°N, 117.7°W. The electrochemical concentration cell balloon sondes and the rocket ozonesondes were both launched from Point Mugu Naval Air Station at 34.2°N, 119.2°W. Stratospheric Aerosol and Gas Experiment (SAGE II) satellite measurements were at various latitudes and longitudes but only measurements made within 1000 km of both of the above sites were considered for this intercomparison study. It was found that at least for the time of year of the study, SAGE II measurements agreed only when they were made much closer than 1000 km (<500 km) from the other sites, and this is explained in terms of the large latitudinal gradient observed in the ozone concentration profile. Agreement to 5% was seen between the instruments, over the altitude range from 20 to 50 km, when the measurements were made close together in both time and space.

During February 1976 a concentrated effort was made to monitor the sea state in the North Atlantic Ocean using Geos 3 radar altimeter wave form data and specialized data processing techniques. The average wave form was computed and fitted in a least squares sense by an error function whose slope is directly relatable to the ocean's significant wave height. The resulting measurements were compared with various sets of truth data. Underflights of Geos 3 orbits were made by a NASA C‐54 aircraft equipped with two narrow pulse radar systems. Additionally, buoy measurements from selected National Data Buoy Office data buoys, hindcasts from experienced analysts in the National Weather Service, and shipboard observations and wave recorder data from Ocean Weather Station ships located in the North Atlantic were collected for comparison with the satellite information. Excellent agreement exists between the aircraft, buoy, and satellite data. Contour maps produced twice daily for February using Geos 3 measurements are compared with the computer‐produced operational hindcast maps from the Navy Fleet Numerical Weather Central and the National Meteorological Center and are found to compare favorably with the Navy product. Differences between the Geos 3 measured magnitudes and locations of major significant wave height features with those found on the operational maps can be explained as the result of atmospheric primitive‐equation model tendencies to underestimate systematically the intensity of oceanic cyclones and to underestimate their speed of movement across the ocean. Using the interpolated wave height values from the Geos 3 February contour maps at the location of Ocean Weather Station Lima, it is shown that the quality of the Geos 3 map is degraded mainly when the narrow swath width of the satellite ground track does not overlay the ocean region with the highest sea state. Even so, the interpolated Geos 3 measurements are in closer agreement with Ocean Weather Station Lima wave recorder data than are Lima shipboard observations of sea state. Hence the satellite altimeter measurements are of better quality than routinely used significant wave height observations, are produced globally, and should be utilized in activities such as ship routing and weather forecasting.

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An airborne radar altimeter operating at 36 GHz is uniquely capable of measuring the topography of water, land, and ice surfaces. The Multimode Airborne Radar Altimeter (MARA) was designed to combine a narrow transmitted pulsewidth, a high transmitted power level, and a narrow antenna beam to produce a high-precision ranging capability at the nadir of the aircraft platform and at four fixed off-nadir angles out to 12" in the multibeam mode described in this paper, or a single beam scanning between *22" in the scanning radar altimeter mode. Data collected over water and land surfaces are presented to demonstrate the potential of MARA for topographic mapping with accuracies and precisions of value in dynamic oceanography, geodesy, geology, hydrology, biogeochemistry, biogeography, and glaciology.

We report the results of a set of ozone measurements at the NASA Wallops Flight Facility (37.8°N, 75.5°W) from August 1983 to September 1985. Nineteen profiles were obtained during this period, using ROCOZ‐A and electrochemical concentration cell ozonesondes, standard U.S. meteorological radio‐sondes, and Super‐Loki datasondes. Complete profiles of ozone, pressure, and temperature were obtained from the ground to 52 km, and 18 of the profiles correspond to site overpasses by ozone instruments on NASA and National Oceanic and Atmospheric Administration (NOAA) satellites. The profiles from this data set show reasonable agreement with established ozone climatologies. The annual ozone variability from the data set is roughly two thirds of the variability from the ozone model for the U.S. Standard Atmosphere (1976). The agreement between total ozone measurements from this data set and concurrent Dobson direct‐Sun total ozone measurements is excellent. The precision of ROCOZ‐A ozone values has been measured at the 3% level (1σ), and the accuracy of the ozone values is estimated at 5–7%. Since the ROCOZ‐A radiometers are expendable, the long‐term repeatability of the ozone measurements is based on a calibration facility which uses standards that are traceable to the National Bureau of Standards (NBS). The assembly of ROCOZ‐A ozone, pressure, and temperature measurements presented here allows the use of this data set as a transfer standard between satellite instruments with different fundamental ozone measurements. In addition, this data set can be used for comparisons of modeled and measured ozone amounts in the stratosphere and lower mesosphere. Such comparisons should prove valuable, since model results are typically 30–50% lower than measured ozone concentrations at altitudes above 35 km.