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NASA NTRS1981

Implications of smaller concentrations of stratospheric OH - A two-dimensional model study of ozone perturbations

There is growing observational evidence that stratospheric OH concentrations are smaller than models have been predicting. Using very recent HOx reaction rate coefficient measurements in a two-dimensional photochemical model, results which support these observations are obtained. As a consequence of smaller OH concentrations, we show that perturbations of stratospheric ozone by NOx (SST emissions and nitrogen fertilizers) may be larger than expected, while perturbations due to added water vapor and chlorine (SSTs and chlorofluoromethanes, respectively) may be smaller.

Whitten, R. C.↗

NASA NTRS1982

The outlook for advanced transport aircraft

The technological advances most likely to contribute to advanced aircraft designs and the efficiency, performance, and financial considerations driving the development directions for new aircraft are reviewed. Fuel-efficiency is perceived as the most critical factor for any new aircraft or component design, with most gains expected to come in areas of propulsion, aerodynamics, configurations, structural designs and materials, active controls, digital avionics, laminar flow control, and air-traffic control improvements. Any component area offers an efficiency improvement of 3-12%, with a maximum of 50% possible with a 4000 m range aircraft. Advanced turboprops have potential applications in short and medium haul subsonic aircraft, while a fuel efficient SST may be possible by the year 2000. Further discussion is devoted to the pivoted oblique wing aircraft, lightweight structures, and the necessity for short payback times.

Leavens, J. M., Jr.↗

NASA NTRS1981

Evaluation of Nimbus 7 SMMR sensor with airborne radiometers and surface observations in the Norwegian Sea

Measurements made by the Nimbus 7 SMMR are compared with near simultaneous observations using the airborne SMMR simulator and with surface observations. The area of the test is in the Norwegian Sea between Bear Island and Northern Norway. It is noted that during the observation period two low-pressure systems were located in the test area, giving a spatial wind variation from 3-20 m/s. It is shown that the use of the currently available brightness temperatures and algorithms for SMMR does not give universally satisfactory results for SST and wind speed under extreme weather conditions. In addition, the SMMR simulator results are seen as indicating the need for more work on calibration.

Gloersen, P.↗

NASA NTRS1982

Signal analysis and error analysis studies for a Geopotential Research Mission (GRM)

The signal characteristics and the geopotential parameter recovery capability of the SST Doppler sensor flown on the geopotential research mission (GRM) are discussed. Simulation studies of the velocity profiles resulting from the perturbation produced by a 1 deg/w/1 deg, 1 mgal anomaly as sensed by two GRM spacecraft orbiting altitudes of 160 km and 200 km respectively are described. It was found that the amplitude of the gravity signal drops off by a factor of 1.5 when going from an altitude of 160 km to 200 km. By extrapolation the signal amplitude is further decreased by a factor of 3 when the orbital altitude is increased to 250 km. Thus the amplitude of the measurement drops off as the altitude is increased to the point where it is insignificant at the 1 mgal level for altitudes above 200 km. Spectral analysis results show that for a GRM mission altitude of 160 km and a system precision of 1 micrometer/sec, gravity field information can be sensed up to 230 cycles per orbital revolution - beyond that frequency the gravity signal is characterized by white noise. It follows that at the GRM mission altitude of 160 km and a satellite to satellite Doppler system precision of 1 micrometer per second, 1/1 deg gravity and geoid anomalies can be determined to an accuracy of 3.4 mgals and 8.6 cm respectively.

Kahn, W. D.↗

NASA NTRS1983

Experiments using atmospheric forcing from a FGGE analysis to drive an upper ocean model

Results are presented of a series of numerical experiments in which an upper ocean model is driven by surface heat fluxes and stress fields derived from the FGGE SOP-1 GLAS analysis/forecast system (Halem, et al., 1982). The model results show that most changes in the mixed layer height and horizontal velocity occurs in the first days. On the other hand, changes in the temperature field take a longer time to develop. In the most realistic case (real initial conditions, instantaneous forcing fields from the atmospheric analysis), the resulting changes in temperature were larger than observed and the correlation between observed and predicted changes was poor. The deficiency in the forecast of SST changes may be due to several factors: lack of sufficient ocean resolution, improper initialization, lack of feedback between the ocean and the atmosphere and the absence of transports by the strong boundary currents, and perhaps unrealistic surface fluxes of heat and momentum. Unless these problems are alleviated it is not reasonable to perform coupled atmospheric ocean forecasts.

Camerlengo, A.↗

NASA NTRS1983

Diagnostic analysis and spectral energetics of a blocking event in the GLAS climate model simulation

A synoptic and spectral analysis of a blocking event is presented, with attention given to the temporal evolution, maintenance, and decay of the block. The GLAS numerical climate model was used to generate a blocking event by the introduction of SST anomalies. Wavenumbers 2 and 3 became stationary around their climatological locations, and their constructive interference produced persistent blocking ridges over the west coast of North America and the other over western Europe. Time variations of the kinetic and potential energies and energy conversions during the blocking were performed. Spectrally filtered Hovmoller diagrams were developed for the winter of 1976-77, and showed that long waves were stationary over most of the interval, which featured severe weather conditions.

Chen, T.-C.↗

NASA NTRS1983

In situ data

The evidence indicates that November 1979 was a very climatological month, certainly in the Atlantic. This must make us particularly wary of deviations from climatology anywhere in the globe during this period. The McLain and Pazan SST analyses are identical to within a degree. The Pazan ship data need to be edited against climatology in order to remove bad ship data.

Pazan, S.↗

NASA NTRS1983

NOAA satellite-derived operational sea surface temperature products

The National Oceanic and Atmospheric Administration (NOAA) began processing global measurements of emitted radiation in the 10.5 to 12.5 micron atmospheric window for purposes of deriving weekly composite and mean monthly sea surface temperature fields in the early 1970s. Atmospheric attenuation corrections, begun with empirical means, were accomplished chiefly with the aid of coarser resolution measurements from atmospheric sounders aboard the same polar orbiting spacecraft. Cloud filtering depended heavily upon the use of histogram techniques applied to 11 x 11 arrays of 8 km resolution Scanning Radiometer Infrared (SRIR) data. Details of the SRIR processing for SST are found in a NOAA Technical Memorandum.

Mcclain, E. P.↗

NASA NTRS1983

Three-way partitioning of sea surface temperature measurement error

Given any set of three 2 degree binned anomaly sea surface temperature (SST) data sets by three different sensors, estimates of the mean square error of each sensor estimate is made. The above formalism performed on every possible triplet of sensors. A separate table of error estimates is then constructed for each sensor.

Chelton, D.↗

NASA NTRS1984

Remote sensing of air-sea interactions

A number of preliminary concepts for the measurement or inference of fluxes across the air-sea interface through remote sensing are proposed. All the methods are achievable from aircraft with state-of-the-art technology. Only one is now ready for space implementation. The focus is on cold outbreaks. Sensible (latent) heat flux is inferred from the difference between initial surface air temperature (vapor mixing ratio) and the downwind SST (and corresponding saturation mixing ratio). The downwind growth rate of the PBL as measured by lidar also provides estimates of surface heating and the cross-inversion entrainment velocity. The lidar also provides a measure of the depth of the inversion and its penetration by surface-forced convection; this permits estimates of the surface heat flux. Lidar and radiometric measurements of cloud top height and temperature provide means of deducing the temperature sounding downstream so that heating is computed with the aid of a known sounding upstream.

Atlas, D.↗

NASA NTRS1984

Satellite-Derived Sea Surface Temperature: Workshop-2

Global accuracies and error characteristics of presently orbiting satellite sensors are examined. The workshops are intended to lead to a better understanding of present capabilities for sea surface temperature measurement and to improve measurement concepts for the future. Data from the Advanced Very High Resolution Radiometer AVHRR and Scanning Multichannel Microwave Radiometer is emphasized. Some data from the High Resolution Infrared Sounder HIRS and AVHRR are also examined. Comparisons of satellite data with ship and eXpendable BathyThermograph XBT measurement show standard deviations in the range 0.5 to 1.3 C with biases of less than 0.4 C, depending on the sensor, ocean region, and spatial/temporal averaging. The Sea Surface Temperature SST anomaly maps show good agreement in some cases, but a number of sensor related problems are identified.

Njoku, E. G.↗

NASA NTRS1984

Sea surface temperatures from Nimbus-7 SMMR radiances

Global displays of sea surface temperatures (SSTs) from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) are obtained with spatial sampling intervals as small as 50 km rather than the 150 km spacing normally used for such retrievals. An example is illustrated using a composite global SMMR data set for January 1979, a preliminary version of the SST retrieval algorithm, and a sampling interval of 100 km. The results were found to be in qualitative agreement with in situ and climatic data, insofar as such comparisons were attempted. In addition to the expected climatic patterns, the global oceanic isotherms contain oscillations that are clearly not instrumental but geophysical in nature.

Gloersen, P.↗

NASA NTRS1985

A Concept for the Processing and Display of Thematic Mapper Data

The thematic mapper system provides spectral information in seven carefully selected spectral bands. The challenge is to devise the best approach for presenting this complex spectral information in a pictorial format which can be understood and accepted as a standard by the growing user community. For photointerpretation purposes, the overall approach in the processing of multispectral, and especially of Thematic Mapper data is based on the Independent definition and optimization of individual panchromatic and spectral (interpretive) components and the combined display of these individual interpretive components in a perceivable manner. Processing of the Thematic Mapper data within the framework of interpretive components requires the application of special intensity, hue, saturation (IHS) and synthetic stereo (SST) display techniques. The results to date using these techniques demonstrate improved visual separability of spectral surface categories relative to standard multispectral color composites as well as a greater potential for conducting meaningful spectral-diagnostic analysis.

Haydn, R.↗

NASA NTRS1984

Quaternary North Atlantic Surface Paleoceanography in Regions of Potential Deep-water Formation

At the time scale of the Quaternary climate cycles, the sites of formation of North Atlantic Deep Water are not known. The interglacial extreme is presumably exemplified by the modern regions; the Norwegian, Greenland and Labrador Seas. During the major glacial-age coolings in the North Atlantic, the sites may have shifted well to the south, perhaps as far as the limit of the polar front at 40 to 50 N. Still other sites may have been important during intermediate climatic conditions. Because of the close coupling of high-latitude surface waters to North Atlantic Deep Water in the modern ocean, the history of sea-surface temperature (SST) oscillations across the high-latitude North Atlantic is relevant to an understanding of deep-water formation on the longer time scales.

Ruddiman, W. F.↗

NASA NTRS1985

Supersonic Cruise Technology

The history and status of supersonic cruise research is covered. The early research efforts of the National Advisory Committee for Aeronautics and efforts during the B-70 and SST phase are included. Technological progress made during the NASA Supersonic Cruise Research and Variable Cycle Engine programs are presented. While emphasis is on NASA's contributions to supersonic cruise research in the U.S., also noted are developments in England, France, and Russia. Written in nontechnical language, this book presents the most critical technology issues and research findings.

Mclean, F. Edward↗

NASA NTRS1985

Preliminary Results from Numerical Experiments on the Summer 1980 Heat Wave and Drought

During the summer of 1980, a prolonged heat wave and drought affected the United States. A preliminary set of experiments has been conducted to study the effect of varying boundary conditions on the GLA model simulation of the heat wave. Five 10-day numerical integrations with three different specifications of boundary conditions were carried out: a control experiment which utilized climatological boundary conditions, an SST experiment which utilized summer 1980 sea-surface temperatures in the North Pacific, but climatological values elsewhere, and a Soil Moisture experiment which utilized the values of Mintz-Serafini for the summer, 1980. The starting dates for the five forecasts were 11 June, 7 July, 21 July, 22 August, and 6 September of 1980. These dates were specifically chosen as days when a heat wave was already established in order to investigate the effect of soil moistures or North Pacific sea-surface temperatures on the model's ability to maintain the heat wave pattern. The experiments were evaluated in terms of the heat wave index for the South Plains, North Plains, Great Plains and the entire U.S. In addition a subjective comparison of map patterns has been performed.

Wolfson, N.↗

NASA NTRS1984

The revolutionary impact of evolving aeronautical technologies

Recent advances in aeronautical technologies which could produce revolutionary changes in transport aircraft if fully implemented are delineated. Laminar flow control offers a L/D improvement from the current 18 to 22 if used with a 767 configuration. Higher aspect and thickness/chord ratios could yield more efficient structural designs and further drag reduction. High-strength, fiber-reinforced composite structures can reduce structural weight by 10-30 percent. Improved engine cooling methods, higher stage loadings and exhaust temperatures can lower the SFC by 15 percent, engine weight by 15 percent, and the parts count by 50 percent. Aft-mounted counterrotating propellers can potentially decrease the SFC an additional 15-20 percent. Supersonic transport aircraft with L/D ratios of 18 and 70 seat miles/gal fuel efficiency can now be built that weigh half as much as the Concorde and carry the same load. The new SST would have superplastic-molded Al alloy structures.

Kayten, G. G.↗

NASA NTRS1984

Satellite color observations of the phytoplankton distribution in the eastern Equatorial Pacific during the 1982-1983 El Nino

Images provided by the Coastal Zone Color Scanner (CZCS) onboard Nimbus-7 show the effect of the 1982-1983 El Nino upon the phytoplankton distribution around the Galapagos Islands, located on the equator. The CZCS scenes document a major redistribution of phytoplankton around the Galapagos Island during a period when sea-surface temperatures (SST) were anomalously high (28 to 29 C). The mixed layer was unusually thick for this region, and the winds and both the surface and subsurface flows changed directions. It is pointed out that the El Nino is characterized as one of the most spectacular examples of a large-amplitude, interannual response of the ocean to atmospheric forcing. The 1982-1983 El Nino is the best documented event of its kind to date, and details of its effects are discussed.

Feldman, G.↗