C-130 Hercules Research Articles

The Retrieval of Stratocumulus Cloud Properties by Ground-Based Cloud Radar

The radiative characteristics of stratocumulus clouds are dependent upon their microphysical properties, primarily the liquid water content and effective radius of the drop population. Aircraft observations of droplet spectra in warm stratocumulus over the North Atlantic and around the British Isles by the Hercules C-130 aircraft of the U.K. Meteorological Office Meteorological Research Flight have been used to calculate the radar reflectivity, liquid water content, and effective radius. Empirically derived relationships, found from more than 4000 km of flight data on 11 separate days, that link reflectivity with either liquid water content or effective radius have been derived. These empirical relationships are significantly different from those predicted if the cloud droplet spectrum is modeled as a gamma function. Occasional drizzle-sized drops are frequently present within the cloud, and even though their concentration is very low, they dominate the reflectivity and these empirical relationships fail. However, although the drizzle drops increase the reflectivity, they have a negligible effect on the liquid water content and effective radius of the cloud. As these drops have a significant fall velocity in comparison to the cloud droplets, it is suggested that a ground-based Doppler radar could separate the components of the reflectivity due to bimodal drop spectra and the vertical structure of the cloud properties that determine radiative transfer could be retrieved.

Determination of areal surface-feature coverage in the Beaufort Sea using aircraft video data

The surface-energy budget of the Arctic Ocean depends on the distribution of various sea-ice features that form by both mechanical and thermodynamic processes. Melt ponds, new ice and open water greatly affect the determination of surface albedo. However, even basic measurements of some surface-feature characteristics, such as areal extent of melt ponds, remain rare.A method has been developed to assess the areal coverage of melt ponds, new ice and open water using video data from the Beaufort and Arctic Storms Experiment (BASE). A downward-looking video camera mounted on the underside of a Hercules C-130 aircraft provided clear images of the surface. Images acquired over multi-year ice on 21 September 1994 were analyzed using a spectral technique to determine the areal coverage of melt ponds, new ice and open water. Statistics from this analysis were then compared to previous field studies and to the Schramm and others (in press) sea-ice model.

Determination of areal surface-feature coverage in the Beaufort Sea using aircraft video data

The surface-energy budget of the Arctic Ocean depends on the distribution of various sea-ice features that form by both mechanical and thermodynamic processes. Melt ponds, new ice and open water greatly affect the determination of surface albedo. However, even basic measurements of some surface-feature characteristics, such as areal extent of melt ponds, remain rare.A method has been developed to assess the areal coverage of melt ponds, new ice and open water using video data from the Beaufort and Arctic Storms Experiment (BASE). A downward-looking video camera mounted on the underside of a Hercules C-130 aircraft provided clear images of the surface. Images acquired over multi-year ice on 21 September 1994 were analyzed using a spectral technique to determine the areal coverage of melt ponds, new ice and open water. Statistics from this analysis were then compared to previous field studies and to the Schramm and others (in press) sea-ice model.

Aircraft measurements of potential vorticity and Richardson number in baroclinic zones

This paper describes a novel technique for deriving potential vorticity and Richardson number from aircraft cross-sections of baroclinic zones. It exploits the fact that gravity waves distort isentropic surfaces, so that an aircraft flying horizontally can measure a vertical profile of temperature and wind under favourable conditions. The technique is applied to two flights of the UK Meteorological Research Flight's C-130 Hercules aircraft, in April 1983 and June 1991. It is found to work reasonably well only when large-amplitude gravity waves are present. Values of potential vorticity so derived agree with those calculated in the conventional manner from cross-sections, and are found to correlate well with ozone mixing ratio.

The Stable Internal Boundary Layer over a Coastal Sea. Part II: Gravity Waves and the Momentum Balance

Observations of the mean and turbulent structure of the marine atmospheric boundary layer (MABL). obtained using the U.K. Meteorological Research Flight C-130 Hercules aircraft are used to investigate the momentum balance over the Irish Sea when warm air is advected offshore. The marine boundary layer is made up of two layers: a strongly stable internal boundary layer (IBL). and a stable residual layer located between the top of the IBL and the base of the planetary boundary layer inversion. Measurements obtained near the upwind coast indicate that the flow is highly ageostrophic. Downwind of the Irish coast, there is a transition toward equilibrium between the geostrophic, Coriolis. and friction components of the flow along part of the flight track. However, another segment of the flight track indicates an imbalance between the pressure gradient and the other measured terms, which may be attributable to gravity waves affecting the adjustment process. This is more apparent in the leg perpendicular to the coast where the pressure gradient is balanced by the observed acceleration with negligible contributions from the Coriolis and friction terms. Gravity waves associated with mountain lee waves propagate along the direction of the mean wind shear in the IBL, which is directed to the right of the wind measured along the flight track perpendicular to the coast at 30-m altitude. The dominant wavelength is about 19 km, which corresponds with the buoyancy frequency of the MABL new the Irish coast and is supported by satellite images of the cloud structure. Farther downstream the buoyancy frequency increases, but the longer wavelength signal remains dominant. An important result of the gravity waves is the modification of the wind field and wind stress within the IBL. The largest effect is observed in the stress direction, but large changes in magnitude are also observed. The results indicate that the direction of the wind stress corresponds to a large degree with the direction of the mean horizontal wind sheer.

Measurements of peroxides in the atmosphere and their relevance to the understanding of global tropospheric chemistry

Peroxides are produced as termination products in atmospheric chain reactions involving peroxy radicals, both organic and inorganic. They are the principal sink for radicals produced in the troposphere from the photolysis of ozone in the presence of water vapour and as such are excellent indicators of the extent of free radical chemistry taking place at any given location. Their measurement is relatively simple and data on the concentration of peroxides in the atmosphere with respect to time and space can be collected easily and extensively.New data on peroxide measurements collected at different parts of the atmosphere, principally by the Meteorological Office C-130 Hercules aircraft are presented. They indicate that the extent of hydroxyl radical chemistry during the summer is controlled mostly by the water vapour content of the atmosphere. Both negative and positive correlations are observed between ozone and peroxide concentrations in vertical profiles over the North Atlantic Ocean and the equatorial Pacific. The negative correlations demonstrate that the ozone concentration throughout the troposphere is determined mostly by in situ photochemistry. This is borne out by the close correlation between calculated and measured concentrations of peroxides in vertical profiles. Positive correlations over the North Atlantic allow us to make an estimate of the amount of ozone, present there in the summer, which is formed from tropospheric as opposed to stratospheric chemistry.

Airdrops and king penguins: a potential conservation problem at sub-Antarctic Marion Island

ABSTRACTEvidence for the disturbance of king penguins (Aptenodytes patagonicus) and other seabirds at sub-Antarctic islands by fixed-wing aircraft making airdrops is reviewed. Based on direct observations of panicking birds at king penguin colonies at Marion Island as Lockheed C-130 Hercules aircraft flew past, it is postulated that the incident at Macquarie Island in 1990 when many king penguins were found dead shortly after a flypast was most likely caused by panic induced by the aircraft's passage. Visits by fixed-wing aircraft to sub-Antarctic islands should be kept to a minimum and no airstrips should be built on them. Specific recommendations are given for fixed-wing aircraft visits to Marion Island, in order to reduce disturbance to king penguins and other seabirds to the absolute minimum. These recommendations should be adopted at all sub-Antarctic islands.

The Measurement and Parameterization of Effective Radius of Droplets in Warm Stratocumulus Clouds

Observations from the Meteorological Research Flight's Hercules C-130 aircraft of the microphysical characteristics of warm stratocumulus clouds have been analyzed to investigate the variation of the effective radius of cloud droplets in layer clouds. Results from experiments in the eastern Pacific, South Atlantic, subtropical regions of the North Atlantic, and the sea areas around the British Isles are presented. In situations where entrainment effects are small the (effective radius)3 is found to be a linear function of the (volume-averaged radius)3 in a given cloud and can thus be parameterized with respect to the liquid water content and the droplet number concentration in the cloud. However, the shape of the droplet size spectrum is very dependent on the cloud condensation nuclei (CCN) characteristics below cloud base, and the relationship between effective radius and volume-averaged radius varies between maritime air masses and continental air masses. This study also details comparisons that have been made in stratocumulus between the droplet number concentrations and (a) aerosol concentrations below cloud base in the size range 0.1 to 3.0 μm and (b) CCN supersaturation spectra in the boundary layer. A parameterization relating droplet concentration and aerosol concentration is suggested. The effects of nonadiabatic processes on the parameterization of effective radius are discussed. Drizzle is found to have little effect near cloud top, but in precipitating stratocumulus clouds the parameterization breaks down near cloud base. Comparisons are made between this parameterization of effective radius and others used currently or in the past.

Future Large Aircraft (FLA): European collaboration or buying off‐the‐shelf?

The aerospace industry has been identified as a key player in the restructuring of the European defence industry as a whole and the British government has seemed keen to support the role of the UK aerospace industry in this process. However, the decision to withdraw from the European attempt to develop a new alternative transport aircraft and to favour an American upgrade of the C130 Hercules has brought this commitment into question. John Appleby and Gordon Gilbert examine the issues and options surrounding this dilemma and its implications.

Relationships between stress, psychological factors, health, and immune levels among military aviators

Abstract The present study investigated the relationship between immunoglobulin levels and work stress and personality factors in a population of healthy air force aviators, and also if such factors were related to health complaints. Sixty-four aviators participated, 31 fighter pilots and 33 from a Hercules C130 squadron. Significant correlations were found between environmental stress factors, perceived health complaints and levels of immunoglobulin and complement components. ‘Psychological defence’ correlated with immunoglobulin levels. In a multiple regression analysis, 31% (p<0.05) of the variance for C3 could be explained by perceived work stress and 15% (p<0.05) of the IgA variance by ‘psychological defence’ and ‘complaints related to immune status'. The results confirm that immunological parameters may be used as psychological stress indicators, but the relationships are complex and can be best understood if individual coping and defence strategies are considered.

Use of Holography for Airborne Cloud Physics Measurements

Abstract The use of the holographic cloud particle imaging system developed by the Cloud Physics Branch of the Meteorological Office and carried on the C-130 Hercules aircraft of the Meteorological Research Flight (MRF) has hitherto been limited by the extremely labor intensive data extraction process. A new image reconstruction system has now been developed that enables numerous holograms from a single flight to be analyzed. A brief description of this system is given, and some of its uses and limitations are demonstrated by examples of both droplet and ice-crystal data. In each case, the holographic data are compared with those from what are now conventional cloud microphysical probes, principally the ASSP and 2-D Optical Array Probe. Results show that the holographic system can measure gross features of the droplet size spectrum in conditions when the ASSP data may be unreliable. Ice crystal measurements confirm the ability of the holographic technique to produce data down to sizes of about 60 μm, well...

MEASUREMENT AND PREDICTION OF DEPOSITIONAL ACCURACY IN DISPERSANT SPRAYING FROM LARGE AIRPLANES

ABSTRACT Aerial application of dispersants has progressed to include very large airplanes, such as the Hercules C-130, for which a portable spray unit has been developed. This unit, which can be rapidly placed in the cargo aircraft (without any mechanical alterations) was flight tested with spraying of a dispersant concentrate in 1982. The tests measured actual deposition of chemical under various conditions. The most definitive data were collected using a “deposition track,” positioned on the ground across the flight path of the airplane. The dyed dispersant was recovered from this track and the data converted to amount per unit area, and to percent of total pumped fluid on-target. The results led to correlation of depositional accuracy in terms of the air shear experienced by the sprayed fluid. The data has been further used to develop a mathematical prediction for design of dispersant treatment procedures using high-speed airplanes. Use of these considerations in operational planning can improve dispersant dosage control by preventing both under-treatment and wasteful off-target drift.

Kontur: Observations of cloud streets and open cellular structures

Abstract In September and October 1981 the experiment KonTur (Convection and turbulence) was conducted over the North Sea. Its objectives were to investigate organized convective patterns, like cloud streets (boundary layer rolls) and cellular cloud structures. Two aircraft (British Hercules C-130 and German Falcon 20) performed detailed measurements within these patterns. Several cases of cloud streets and open cells were observed. Boundary layer rolls appear to be connected with an inflection point in the cross-roll wind component. The aspect ratio of the rolls (wavelength versus depth) is between three and four in accordance with other observations and linear stability analysis. Four scales of motion are involved: the mean flow, the roll circulation, individual clouds and turbulence. The vertical transport are dominated at lower levels by turbulence and at higher levels by roll-scale motions. Open cellular cloud structures are connected with large air-sea temperature differences due to cold air outbreaks from the northwest. The aspect ratio of the cells is of the order of 10. The bulk contribution to the total transport of heat and momentum originates from the cloudy walls of the cells. A vertical cross section through a composite open cell is presented.

Transportation Requirements for Drilling Operations on the Arctic North Slope of Alaska

Summary Since the OPEC oil embargo of 1973, U.S. oil companies have been placing increasing emphasis on exploring for and producing oil located within the U.S. Alaska's North Slope has received a great amount of attention recently as there exists a known transportation system (the Trans Alaska pipeline) and because geological information indicates the potential for pipeline) and because geological information indicates the potential for large producing reservoirs. Drilling on Alaska's Arctic North Slope poses a number of interesting operational problems, including transporting and supporting drilling rigs to their respective locations. Sohio Alaska Petroleum Co. has extensive experience in transporting and supporting drilling figs in development operations (Prudhoe Bay) and exploration locations both on- and offshore Alaska's Noah Slope. This paper addresses how arctic drilling figs are transported to development locations within the Prudhoe Bay Unit and to remote on- and offshore locations. Principal topics deal with the current methods by which rigs are moved and how daily drilling operations are supported. In addition, this paper discusses transportation systems that may be required when drilling operations extend beyond the Barrier Islands of Alaska's North Slope. Introduction Drilling operations on Alaska's North Slope have come a long way since the discovery of oil at Prudhoe Bay in 1968. During the early days of drilling at Prudhoe, rigs were transported to the Slope by Hercules C-130 aircraft, barges up the west coast of Alaska, or cat trains up the 375-mile [603-km] winter-haul road out of Fairbanks. In 1975, the all-weather Trans Alaska pipeline haul road to Prudhoe Bay was completed, which provided an pipeline haul road to Prudhoe Bay was completed, which provided an alternative method to bring rigs to the slope. This paper explains how drilling figs are transported to drilling locations on Alaska's North Slope. The figs and support equipment now being used in the development of Prudhoe Bay have day rates that exceed $50,000. To minimize the time it takes in the Prudhoe Bay field to move a fig from one well to the next requires the use of specially designed fig-transportation systems. Two such systems are described, one with rollers on skids and another with rubber-tire wheels coupled to a jacking system. Exploration drilling up to 60 miles [97 km] from Prudhoe Bay is being conducted. This work involves moving Prudhoe Bay development rigs to both on- and offshore locations. This paper discusses moving rigs to exploration locations by Hercules aircraft, rolligons, trucks over ice roads, and barges-the methods being used by most operators drilling on the North Slope. Arctic North Slope Environment The North Slope of Alaska is bordered to the north by the Chukchi and Beaufort Seas and to the south by the Brooks Mountain Range (Fig. 1). The entire 90,000 sq miles [233 099 km 2] of land making up the North Slope lies wholly above the Arctic Circle. Prudhoe Bay, the largest oil field in North America, is located within this region and occupies about 0.5% of the overall area. Situated on the edge of the Beaufort Sea, Prudhoe Bay is approximately 250 miles [402 km] north of the Arctic Circle and 1,300 miles [2092 km] south of the North Pole. JPT p. 2308

Bayesian Estimation of Crack Initiation Times from Service Data

Lockheed C-130 Hercules aircraft have during their service life been periodically inspected and growing cracks around rivet holes were recorded. This record has recently been used to determine the statistical distributions of crack initiation times and the distribution of initial crack sizes. When crack initiation times are calculated from such cracks, by backward extrapolation of the growth relation, the resulting distribution of crack initiation times will indicate a preponderance of short times to crack initiation. If however, such distributions are combined with the reliability of the inspection procedure, the statistical distribution of missed initiation times can be estimated. The method used is based on Bayes theorem which permits the calculation of the 'prior' distribution (initiation times before inspection) from a knowledge of the 'posterior' distribution (initiation times obtained from the inspection) and a 'likelihood function' (reliability of the inspection) procedure. The results indicate that during an early inspection a large percentage of initiation times will be missed and that the fraction of located initiation times increases during later inspections.

Geological investigations in northern Peary Land

The authors were in North Greenland from the end of April to the beginning of September as members ofthe British Joint Services Expedition led by Major J. D. C. Peacock R. E. M. E. During this time reconnaissance investigations were carried out in northern Peary Land in an area about 8500 km2. Travel until mid-June was by sledge on the sea-ice, thereafter by ski and on foot in the Roosevelt Fjelde. Resupply was by parachute drops made by an RAF C-130 Hercules aircraft.

Role of sintering in snow construction

BECAUSE of the almost complete lack of roads in the polar regions, the ability to land aircraft on snow has always been of great importance in polar operations. In Greenland the first operation that utilized aircraft landings on snow was that of Ellsworth and Amundsen with Riiser-Larsen and Dietrichson as pilots in 1925. The following year Byrd flew his ski-equipped Fokker trimotor to the North Pole with Floyd Bennett as pilot. In 1928-29 the skiplane was introduced to the Antarctic by Byrd [1]. Since then landing on skis in Greenland and the Antarctic has gradually become a routine matter. Since World War II, prepared runways where large aircraft without skis can operate have predominated. The demand for prepared runways increased with the construction of the early warning sites in Greenland and the Antarctic phase of IGY in 1956. Presently, the large aircraft being used in polar operations are the C-124 (Globemaster) and the C-130 (Hercules), both with wheeled landing gear. The latter is also equipped with a ski-wheeled type modification for Greenland and Antarctic use; however, this reduces the load-carrying capacity. Since not all aircraft are equipped with skis the capability of landing wheeled aircraft on snow runways has become of considerable interest. In addition wheels are much lighter than skis, cause less drag on take off, and have no air drag. For ski-equipped aircraft longer runways are needed to lift the same amount of weight and air speed is lowered appreciably by air drag. A snow runway was constructed at Site II, Greenland, in 1955 and was successfully used for landing wheeled aircraft with cargo (C-124, C-47) and personnel (C-54) [2]. Similar attempts have been made in the Antarctic, but without success. It is the purpose of this paper to theoretically and experimentally analyze the problem of snow runways and establish criteria permitting adequate site evaluation and effective construction of landing strips. The results are applicable not only to polar regions but also to temperate areas with a heavy annual snow accumulation.