High-flying Aircraft Research Articles

ATMOSPHERIC WATER VAPOR PROFILES DERIVED FROM REMOTE-SENSING RADIOMETER MEASUREMENTS

The feasibility and preliminary testing of a low cost, remote-sensing air-borne, double bolometer technique for inferring atmospheric water vapor is illustrated. To deduce the water vapor profile with commercially available equipment, the radiative transfer equation is solved for the water vapor transmissivity employing an input data remote radiometer-measured upward irradiances obtained at aircraft holding levels. Radiometers sensitive in two separate spectral bands are used. The primary radiometer covers the 4.39 to 20.83µ, broad atmospheric radiation band, and the second, for surface temperature deduction, covers the atmospheric window region, 7.35 to 13.16µ. The transfer solution results are acquired from computer programs developed specifically for this purpose. Results indicate an accuracy for inferred total tropospheric water vapor and mixing ratio profiles close to that of the standard sounding electrical hygrometer. The absolute accuracy of the radiosonde hygrometer, considering surface calibration procedures, and for a single ascent, is not better than ±12 percent. The absolute accuracy is greatest for “dry” soundings where the largest changes in irradiance occur for given changes in moisture. Specifically, tests for a vertical profile averaging 6.00 gm./kg. of water vapor produce an average error of 0.70 gm./kg. in the inferred mixing ratio. The average error in mixing ratio obtained by this technique for profiles averaging 2.3 gm./kg. is 0.05 gm./kg. The implications for use on high-flying aircraft or on rockets with highly sensitive radiometers are obvious. The primary purpose in reporting this research is to suggest a technique and illustrate its use. It is clear that with more sensitive bolometer radiometers with selective band pass filters a considerable increase in accuracy can be achieved.

Microwave Radiometric Sensing for Air Navigation

This paper discusses the results of an analytic study of the feasibility of using microwave radiometry as a technique for navigation data sensing in Army aircraft. The study included a review of Army aircraft characteristics and navigation requirements. Various means of sensing passively aircraft velocity, altitude, and velocity-altitude ratio were considered. While there appears to be no practical method for direct measurement of either velocity or altitude separately, it does appear possible to measure velocity-altitude ratio by comparing radiometric signals received from the terrain along the aircraft ground track. When combined with a radar altimeter, such a sensor could yield navigation data compatible with Army aircraft requirements. Microwave radiometry may also be the basis for direction sensing (to known landmarks) in high-flying aircraft or satellites.

Karman vortex streets in wakes of islands.

W satellites equipped with narrow-angle cameras have revealed the existence of mesoscale eddies, which are on a scale too small to be delineated by the standard weather observation network and are too large to be seen by an observer on the ground or even pictured from a high-flying aircraft. Hubert and Krueger have described the characteristic properties of mesoscale eddies formed in the wakes of islands that are steep-sided and extend far above the lowlying inversion. These eddies are made visible by patterns in stratocumulus clouds lying beneath a strong inversion about 0.5 to 2.0 km above the ocean surface and have been observed to persist several hundred kilometers downstream. The bandwidth of the eddies is of the order of the cross-stream diameter of the island. Under favorable conditions, the pattern of the eddies bears a strong resemblance to the classical Karman vortex street pattern observed in laboratory studies of wakes behind obstacles. Figure 1 is a typical example of these eddies in the vicinity of the Madeira Islands. Recently, Chopra and Hubert examined the properties of the eddies downstream of the Tenerife and the Gran Canaria Islands in the light of this apparent resemblance between the meteorological mesoscale eddies and the classical vortex street pattern of Fig. 2. This analogy is analyzed further in this note. Viscosity plays two roles in the flow pattern of a Karman vortex street. First, it leads to the formation of the boundary layer in which vorticity is generated and the vortex pairs are formed, the vortices being shed alternately near each edge of the obstacle. Second, the strength of the eddies is dissipated by the mechanism of diffusion; the size of an eddy increases, and its strength decreases as it propagates downstream, until its region of influence overlaps that of a neighboring eddy of opposite circulation. In all of the other respects, the fluid may be regarded as perfect (inviscid). The rate N of shedding of the eddy pair is given by .V ue/a = (l/a)foo (k/2a) taDh(irh/a)] (1) where ue is the speed of propagation downstream of the eddies in a coordinate system fixed to the obstacle, UQ is the speed of the undisturbed flow, a is the longitudinal spacing (pitch) between two eddies of similar circulation of strength k, and h is the lateral spacing (bandwidth) between the two vortex rows. Drag and Spacing Ratio

The eclipse of 20 July 1963 spectrophotometry of atmospheric emissions

Abstract Observations of atmospheric emissions from a high-flying aircraft were made near Great Slave Lake, N.W.T., Canada during the eclipse of 20 July 1963. Emissions detected in the day airglow were: λ 5577 [OI], λ 6300 [OI] and λλ 5890–5896 (Na). Extrapolation to a fully illuminated atmosphere leads to an estimated intensity of 21 to 33 kR for the NaD lines, with an estimated altitude of 77 ± 5 km. The photon flux of the OI green line was observed to be 780 R at mid-totality while the OI red line measured 630 R near third contact. In the case of λ6300, u.v. dissociation of O2 is estimated to be responsible for less than 0.7 kR of the red line dayglow in the fully illuminated atmosphere. The brightness and spectral distribution of zenith total radiant flux, measured during totality, is comparable to that measured in the zenith during twilight at a solar depression angle of 7°48'. The observed asymmetry of the total light curve about midtotality is attributed to the shape of the Moon.

CLOUD PATTERNS: PART 1: SOME ASPECTS OF THE ORGANIZATION OF CLOUD PATTERNS

Abstract The organization of convective clouds into streets and bands as observed in cloud study field trips, in plots of radar echoes, and in pictures taken by TIROS satellites and high-flying aircraft is described, and some of the physical factors affecting the cloud patterns are discussed. The need for more observational data and for better understanding of atmospheric energetics and dynamics in order to forecast cloud patterns is emphasized.

A note on the ductility of beryllium single crystals oriented for basal slip and tested in tension

A portable spark-chamber range spectrometer and electronic data acquisition system is described for acquiring spectral data on energetic charged particles. The instrument system consists of a uni-directional spark-chamber range telescope with pulse-height analysis of the specific energy loss (dEdx of a charged particle that passes through a triggering telescope. The range telescope consists of a stack of sealed double-gap spark-discharge modules with absorbers sandwiched between them. A Cherenkov counter discriminates against electrons and muons. Cherenkov and dEdx signals are gated by the coincidence circuit. Data, either telemetered or recorded in situ, include the number of coincidences, a clock signal, system voltage levels, and the dEdx, Cherenkov, and spark-discharge module signals. Power consumption of the self-contained system is about 10 W at an event rate of 20 per second and 17 W at an event rate of 100 per second. The standby power is about 8 W. This instrument system can measure primary protons and alphas at balloon altitudes and secondary protons at lower altitudes. A particular configuration with a geometric factor of about 1 cm2 sr has been assembled for measuring atmospheric proton intensities and spectra in the range from MeV to 300 MeV and at altitudes ranging from the altitude of high-flying aircraft to balloon altitudes near the top of the atmosphere.

Some Solar Lines in the Infra-Red Spectrum observed from a High-Flying Aircraft

IN a previous communication1, it was pointed out that strong absorption by atmospheric constituents obscures large parts of the infra-red spectrum from ground-level observation. However, by working at high altitudes and by using a high-resolution spectrometer, it is possible to observe additional features due to absorption in the solar atmosphere. Among these are two absorption lines due to the electronic transitions in solar hydrogen 3–4 and 4–8, which occur in the great water-vapour band at 1.9µ.

Some Observations of the Infra-red Solar Spectrum from a High-flying Aircraft

THE strong absorption bands of water vapour and carbon dioxide in the infra-red obscure much of the solar spectrum from observation on the ground. By working at high altitude, however, it is possible to use measurements of absorption in these bands for obtaining data about the concentration of water vapour and other atmospheric constituents in the upper atmosphere. To make such measurements, an infra-red grating spectrometer with a resolution ∼ 2 cm.−1 has been installed in a Canberra aircraft. A heliostat maintains a steady image of the sun on the input slit of the spectrometer. The spectrometer and heliostat are installed in the unpressurized part of the aircraft necessitating an elaborate system of remote control for its operation.

Radar height-finder developed to detect high-flying aircraft

Radar height-finder developed to detect high-flying aircraft

Atmospheric Winds

The role of meteorology in air operations is becoming increasingly important and an understanding of meteorology is desirable in the consideration of a number of the problems to be faced. The forecasting of winds en route and the use of these forecasts is one such problem, which has been brought into greater prominence by the advent of fast, high-flying aircraft. A great deal of work is being done on upper air winds and it is already clear that curious and significant phenomena sometimes occur. Thus very high winds are sometimes found in belts of limited lateral extent—the so-called “jet stream.” Not only high winds, but high rates of change of wind occur in such regions and they are clearly a potential source of difficulty to the navigator. Apart from the jet stream —a meteorological highlight of recent development—airline operators are also concerned with the problem of route planning.

Experiments on Cosmic Rays in High-Flying Aircraft

A BRIEF announcement has been issued by Dr. Gilbert Grosvenor and Dr. W. F. G. Swann in a News Bulletin of the National Geographic Society of Washington of some experiments on the origin of the meson component of the cosmic rays. The National Geographic Society, the Bartol Foundation and the U.S. Army co-operated in the experiments, which were made in a series of flights in a B29 aircraft at places, ranging from Northern Chile to Southern Canada, from the magnetic equator up to mag. lat. 48° N. and at altitudes up to 33,000 ft. The apparatus consisted of a number of coincidence counters arranged to record penetrating particles of which the direction of motion was in or near the vertical. The soft component (electrons and photons) was prevented from reaching the counters by a sufficient thickness of lead shielding. At 33,000 ft. the observed intensity of the mesons, using this particular experimental arrangement, was observed to increase by 33 per cent in going from mag. lat. 0° to mag. lat. 48°, and 50 per cent at 25,000 ft. The absolute change in intensity with latitude, in contrast with the above values of the relative changes, was greater at the higher altitude than at the lower.