Degrees Of Longitude Research Articles

A fast moving easterly wave of the West Africa troposphere

This paper documents a tropospheric synoptic-scale wavelike disturbance over Northern Africa and the tropical Atlantic during summer, in the 3.–5.day band period, different from the African wave. It has a velocity of 10–12 degree longitude per day instead of 6–8, a slighter shorter period, i.e. 3.5 instead of 4.5 days. It is best seen between 5°–7° N whilst the African wave has its largest amplitude about 12° N. The data used are NCEP/NCAR reanalyses and radiosonde data.

Observations of the Leonids over the Last Millenium

The recognition of the astronomical origin of meteors is intimately connected to the Leonid meteors, and their tendency to “storm” with a period of 33 years. It was the Leonid storm of 1799, observed by Alexander von Humboldt among others, that first established the geographical extent of the phenomenon, with observations reported over 90 degrees of longitude and 60 degrees of latitude. During the 1833 storm, Olmsted (1834) at Yale and Twining (1834) at West Point established the radiant point in Leo, and the cosmic origin was clinched when H. A. Newton (1863), also at Yale, determined that the cycle repeated in intervals of sidereal years, not tropical years. Inspired by the 1866 storm, Adams (1866), Schiaparelli (1867), and Le Verrier (1867) determined a 33.25 year period and other orbital elements for the meteor stream; two years after the discovery of Comet Tempel-Tuttle in 1865, that comet was recognized as the parent body of the Leonid stream after von Oppolzer (1867) calculated a period of 33.17 years for the comet. Astronomers confidently predicted another storm in 1899, but none appeared, though there were good showers in 1901-1903. The years 1930-32 also brought fairly good showers, but 1966 brought the strongest storm witnessed in modern times, with an estimated 100,000 meteors per hour. Steady progress was made in meteor studies in the 20th century, especially with new photographic and radar techniques. The current question is what will happen in the 1997-1999 period; the only certainty is that the event will be studied with an even wider array of techniques.

Easy to use Global and Regional Ionospheric Models — A Report on Approaches Used in Graz

Out of the necessity to provide quick access to ionospheric model data from various computer programs written in different languages (PASCAL, FORTRAN, IDL, etc.) we developed a “data box” approach in the following way: grid point values are calculated from an existing global or regional model and written into a data file. Good values for grid point distances are 5 degrees in latitude, 10 degrees in longitude and 10 km in height. Third order interpolation is used in all grid variables to find the model value where needed. For ray tracing applications splines can be used over the region of interest instead of simple interpolation.

WILDLIFE RESPONSE IN A REMOTE ALASKAN SPILL: TESTING A CENTRALIZED SYSTEM

ABSTRACT In 1991 the International Bird Rescue Research Center, Alyeska Pipeline Service Company, and Alaska Clean Seas teamed up to design and implement a wildlife response system that could work successfully in a state with an area of nearly 600,000 square miles, more than 6000 miles of coastline, and hundreds of islands. In a state that is spread over more than 15 degrees of latitude and 45 degrees of longitude, the system would need to work in all sorts of weather and at all times of the year in three major climatic zones (marine coastal, subarctic, and arctic). It was decided that the best way to maximize resources and coverage was to design a system with a centralized oiled wildlife rehabilitation center in Anchorage: the Alaska Wildlife Response Center. This would allow one to use resources that would otherwise be unavailable in a timely fashion in many of the areas at greatest risk for an oil spill. It would also maximize cost effectiveness by minimizing the amount of equipment and personnel that would have to be moved and supported in remote areas of the state. A centralized system would, however, potentially require that the affected wildlife be transported long distances to be rehabilitated. In February 1996, a spill off the north coast of St. Paul Island in the Bering Sea provided the first real test of this system. It required the capture, stabilization, and transport of nearly 200 oiled birds under quite difficult and typical Alaska conditions. This paper will discuss the problems and solutions encountered in mounting a wildlife response to an oil spill in a remote area with inclement weather conditions and few local resources. It will focus on what makes responding in Alaska different from responding in most other parts of the United States, and on what was done differently in this response to make it a success. This paper will show how a system based on a centralized facility can work successfully, as was evidenced by the high percentage of released wildlife, when it involves teamwork among all organizations, agencies, and individuals involved.

Comparison of the African and the 6–9 day wave-like disturbance patterns over West-Africa and the tropical Atlantic during summer 1985

Using the ECMWF and NMC analyses, this study documents the composite structures of the African and of the 6–9 day waves. In spite of the fact that the two types of disturbances develop over almost the same area, i.e. Central and West Africa and the tropical Atlantic, during the same season, i.e. summer, in spite of the fact that they have almost the same East-West velocity, i.e. 7–8 degree longitude per day, the structures of the two waves are very different.

Convection systems in the dayside polar cap produced by various patterns of the cusp field-aligned currents

The numerical method implies the solution of equations of the integrated electric current continuity. The elliptic partial differential equations in the spherical coordinates are solved numerically to obtain the most probable potential value at each grid points (every 0.5 degrees in colatitude and about 2.5 degrees in longitude). The electrodynamical connection between the ionospheric current sheets in the opposite hemispheres being taken into account. The results of calculation for patterns of the cusp regions currents put forward by Erlandson et al.[1988], Saunders [1992], Yamauchi et al.[1993], Tagichi et al.[1993], Troshichev et al.[1996] show that all these FAC patterns provide very similar distribution of zonal convection flows in the dayside polar ionosphere. It is concluded that the available experimental data cannot simply be used to make a confident choice of FAC pattern.

HOMOGENIZATION OF SWEDISH TEMPERATURE DATA. PART II: HOMOGENIZED GRIDDED AIR TEMPERATURE COMPARED WITH A SUBSET OF GLOBAL GRIDDED AIR TEMPERATURE SINCE 1861

Homogeneity tests of long seasonal temperature series from Sweden, Denmark, Finland, and Norway indicate that homogeneous series are rare and that an abrupt change of the relative mean level is a much more common type of nonhomogeneity than a gradual change. Furthermore, negative shifts were 20% more common than positive shifts. Homogenized temperature anomaly series that were constructed for six 5 degrees latitude x 5 degrees longitude grid boxes indicate that the temporal pattern of temperture changes has been similar in different parts of Sweden since 1861. The annual mean temperature over Sweden was found to have increased by 0.68 degrees C from the period 1861-1890 to 1965-1994. The corresponding changes for the seasons were: +0.18 degrees C (winter), +1.40 (spring), +0.42 (summer) and +0.60 (autumn). A direct comparson shows that non-homogeneities in the temperature series from individual grid boxes in a global data set can be as large as the total changes observed. We estimate that a 95 per cent confidence interval for the error, due to non-homogeneous long station records, in estimates of hemispheric temperature changes over land regions since the period 1861-1890 is +/-0.1 degrees C for the Northern Hemisphere and the globe and +/-0.25 degrees C for the Southern Hemisphere. For a region consisting of about five grid boxes, this error is +/-0.5 degrees C. The large non-homogeneities in individual grid-box series in the global data set is partly a consequence of the fact that homogeneous climate data are not always easily available for the open research community. We urge that efforts are made to improve this situation.

極軌道衛星NOAAに搭載されているSplit Windowで算定された雲型別雲量の昼と夜でのちがい

Split window measurements aboard the NOAA polar orbiting satellites have been used to study cloud cover change between day and night over the western Pacific. The split window technique can discriminate optically thin cirrus type clouds (ice clouds) from optically thick cumulus type clouds. In this study, cirrus and cumulus type clouds are each divided into two classes depending on cloud brightness temperatures (TBB). Cirrus are classified as either warm or cold type, while cumulus type are divided into cumulonimbus type and low-level cumulus/stratocumulus type. From the comparison with ISCCP analysis, mean optical thickness of warm cirrus, cold cirrus, cumulus/stratocumulus and cumulonimbus type clouds were found to be 2.2, 7.4, 15.3 and 33.7, respectively.The diurnal change in cloud cover of the above cloud types is studied for typhoon cases as individual convective systems and for an area of 20 degrees latitude by 30 degrees longitude over the western tropical Pacific. Cumulonimbus type clouds, warm cirrus type clouds and low-level cumulus/stratocumulus type clouds show tendencies toward higher cloud cover at night (about 2:30 local time). Cold cirrus type clouds show a tendency toward more cloud cover during the day (about 14:30 local time).

A 1° × 1° distribution of carbon dioxide emissions from fossil fuel consumption and cement manufacture, 1950–1990

One degree latitude by one degree longitude (1° × 1°) data sets of carbon dioxide emissions from fossil fuel consumption and cement manufacture were produced for 1950, 1960, 1970, 1980, and 1990. National estimates of carbon emissions were combined with 1° × 1° data sets of political units and human population density to create the new 1° × 1° carbon emissions data sets. The human population density data set has an effective resolution of the country/state level. This resolution translates to the 1° × 1° carbon emissions data set. Latitudinal distribution of emissions have also been calculated. The data show continual growth with time over most of the world, with increased growth rates in major urban areas. A slow southerly shift in the bulk of the emissions is apparent as Asian countries increase their energy consumption to support their growing economies and populations. The digital data sets are available by anonymous ftp.

The Gulf of Mexico Air Quality Study - An Industry Perspective

SUMMARY Section 328 of the Clean Air Act Amendments of 1990 required the EPA to promulgate a rule establishing air pollution control requirements for Outer Continental Shelf (OCS) sources. Congress exempted Gulf of Mexico OCS sources west of 87.5 degrees longitude (near the border of Alabama and Florida) pending the results of a "three year" study conducted by the Department of Interior (DOI) – Minerals Management Service (MMS). The study required an examination of the impacts of emissions from OCS activities in such areas that fail to meet the National Ambient Air Quality Standard (NAAQS) for either ozone or nitrogen dioxide. This paper reviews the MMS Gulf of Mexico Air Quality Study's (GMAQS) emission inventory development, historical ozone episode modeling, field sampling, and preliminary photochemical modeling results. Industry has developed a standardized spreadsheet to calculate emissions and a software package to allow operators to figure out the cost to control OCS sources for NO, and VOCs under the EPA's OCS Air Regulations (40 CFR Part 55). Cost estimates are provided for various regulatory scenarios currently being reviewed by the EPA and MMS.

Observations of Saturn's Ring-Plane Crossings in August and November 1995

Observations of Saturn's ring system with the Hubble Space Telescope during the 10 August 1995 Earth crossing and the 17 to 21 November 1995 solar crossing indicate that the F ring dominates their apparent edge-on thickness of 1.2 to 1.5 kilometers. The F ring is slightly inclined with respect to the A ring, which may explain the approximately 50-minute difference in apparent crossing times for the east and west ring ansae in August. Prometheus lags its predicted position by about 19 degrees in longitude. The faint G ring is neutral or reddish in color and is confined to a radial range of 2.72 to 2.85 Saturn radii. The broad, distinctly blue E ring flares outward to a maximum thickness of about 15,000 kilometers at 7.5 Saturn radii and appears to have a spatially uniform particle size distribution.

Columbus's Method of Determining Longitude: An Analytical View

On 14 September 1494, Christopher Columbus observed a lunar eclipse while at the island of Saona near the eastern tip of Hispaniola. He later recorded in his Libro de las Profecias that, from his timing of the eclipse, he determined his longitude to be ‘five hours and more than one half’west of Cape San Vicente. His actual longitude was three hours and 59 minutes west of Cape San Vicente, so Columbus was off by over an hour and a half, some 23 degrees of longitude.

Three‐dimensional numerical simulation of Martian global dust storms

We present results from the first numerical simulations of simultaneously evolving three‐dimensional thermal, dynamical, and radiatively active suspended dust fields in the Martian atmosphere. Simulations of southern summer dust storms (arising from a prescribed southern subtropical surface dust source) conducted with a Mars general circulation model (GCM) illustrate the important role of dust transport by atmospheric eddies. Both traveling and stationary eddies contribute to dust transport to high latitudes in both hemispheres. These hemispheric differences arise from seasonal and topographic effects. Transport into the south polar regions is accomplished primarily by thermally and topographically forced standing eddies. Both traveling and stationary eddies transport dust to middle and high northern (winter) latitudes. Atmospheric wave motions are affected by the developing storms. Thermal tidal amplitudes increase at storm onset, with the calculated pressure response at a model grid point corresponding to the location of the Viking Lander 1 site in good agreement with observations. In qualitative agreement with observations, winter hemisphere baroclinic waves weaken during the early stages of the storm, but as the storm wanes, amplitudes of these waves increase. A slowly westward propagating (9 degrees of longitude per sol) zonal wavenumber one feature in the temperature and geopotential fields at middle northern latitudes amplifies rapidly during the initial sols (Martian solar days) of the simulated storms. This feature is suggestive of the observed north polar warming which occurred during the 1977B global dust storm, but the simulations produce a much weaker polar warming (∼10 K at 0.5 mbar) than was observed (40–50 K). The globally integrated CO2 condensation rate decreases by 15–20% during the simulated dust storm onset and would likely be decreased more if a stronger polar warming were produced. During the initial stages of the simulated storms, surface stress values in the southern subtropics intensify due primarily to the intensification of the Hadley circulation and thermally driven tides. This supports the hypothesis that these components of the general circulation contribute strong positive feedbacks to the developing storms.

Recent space shuttle observations of the South Atlantic anomaly and the radiation belt models

Active instruments consisting of a tissue equivalent proportional counter (TEPC) and a proton and heavy ion detector (PHIDE) have been carried on a number of Space Shuttle flights. These instruments have allowed us to map out parts of the South Atlantic Particle Anomaly (SAA) and to compare some of its features with predictions of the AP-8 energetic proton flux models. We have observed that consistent with the generally observed westward drift of the surface features of the terrestrial magnetic field the SAA has moved west by about 6.9 degrees longitude between the epoch year 1970 of the AP-8 solar maximum model and the Space Shuttle observations made twenty years later. However, calculations indicate that except for relatively brief periods following very large magnetic storms the SAA seems to occupy the same position in L-space as in 1970. After the great storm of 24 March 1991 reconfiguration of the inner radiation belt and/or proton injection into the inner belt, a second energetic proton belt was observed to form at L ⋍ 2 . As confirmed by a subsequent flight observations, this belt was shown to persist at least for six months. Our measurements also indicate an upward shift in the L location of the primary belt from L = 1.4 to L = 1.5. In addition we confirm through direct real time observations the existence and the approximate magnitude of the East-West effect. If the need exists for improved and updated radiation belt models in the Space Station era, these observations point out the specific features that should be considered and incorporated when this task is undertaken.

Spring Migration of the Knot Calidris c. canutus over Southern Scandinavia, as Recorded by Radar

The bird migration pattern in June in southern Scandinavia was analysed on the basis of registrations from six years 1986-1991 by a long-range surveillance radar located in Scania, southern Sweden. The timing of migration, field observations and identification of some echoes suggested that mainly Knots Calidris c. canutus, on their way between the Wadden Sea and breeding grounds along the high arctic coasts of Siberia, were involved in the movements analysed. The daily timing was similar each year, with a peak passage across Scania in the night. The median time of passage (all years combined) was three hours after local sunset. The Knots have probably flown directly from well-known staging sites in the German Wadden Sea, and the median departure time from there was estimated to occur 1 /2 h before sunset. The average track direction was 63 ?+ 140 angular deviation. This is slightly, but significantly, to the south of the constant compass bearing (rhumbline = 570) between the German Wadden Sea and possible destination areas on the north coast of the Taymyr Peninsula in Siberia. Track directions varied significantly with wind, suggesting partial drift or pseudodrift. The groundspeed (25.6 m s-1) was on average 6.1 or 7.6 m s-1 (depending on the assumed flight altitude) faster than the estimated airspeed, showing that the majority of flocks had considerable tailwind assistance. Significantly more echoes were recorded in tailwinds than in winds from other directions relative to the average track direction. Evaluation of course changes of echoes tracked while crossing five degrees of longitude, over distances up to 400 km, showed that the birds did not follow any of the predicted paths according to known orientation mechanisms (sun-, star-, magnetic compasses). Rather, the overall migration route may be influenced by topography in a way that maximizes association with coastal areas.

Aerosol abundances and optical characteristics in the pacific basin free troposphere

During NASA's Global Backscatter Experiment (GLOBE) mission flights in November 1989 and May 1990, a DC-8 research aircraft probed the Pacific Basin free troposphere for about 90 flight hours in each month between +72 and -62 degrees latitude, +130 and -120 degrees longitude, and up to 39,000 feet pressure altitudes. Aerosols were sampled continuously in situ by optical particle counters to measure concentration and particle size, and during 48 10-min intervals during each mission by wire impactors for concentration, size, composition, phase and shape analyses. The optical particle counters cover a particle diameter range between 0.3 and 20 microns; wire impactors extend the range down to 0.03 microns. Results of particle number, size, shape, together with the assumption of a refractive index corresponding to (NH4)2SO4 to account for the prevalence of aerosol sulfur, were utilized in a Mie algorithm to calculate aerosol extinction and backscatter for a range of wavelengths (0.385 less than lambda less than 10.64 microns). Computations for 22 randomly selected size distributions yield coefficients of extinction E(0.525) = (2.03 +/- 1.20) x 10(exp -4) km(exp -1) and backscatter beta(0.525) = (6.45 +/- 3.49) x 10(exp -6) km(exp -1) sr(exp -1) in the visible, and E(10.64) = (8.13 +/- 6.47) x 10(exp -6) km(exp -1) and beta(10.64) = (9.98 +/- 10.69) x 10(exp -8) km(exp -1) sr(exp -1) in the infrared, respectively. Large particles (D greater than 0.3 microns) contribute two-thirds to the total extinction in the visible (lambda = 0.525 microns), and almost 100% in the infrared (lambda = 10.64 microns). These results have been used to define an IR optical aerosol climatology of the Pacific Basin free troposphere, from which it follows that the infrared backscatter coefficient at lambda = 9.25 microns wavelength fluctuates between 5.0 x 10(exp -10) and 2.0 x 10(exp -7) km(exp -1) sr(exp -1) with a modal value 2.0 x 10(exp -8) km(exp -1) sr(exp -1).

Combined temperature-precipitation variations in Austria during the instrumental period

Using a dense network of carefully tested and homogenized long-term temperature and precipitation data this paper describes climatic variations during the last 150 years for both these important climatic elements. It turned out that the response of precipitation to climate warming is quite different within a small region, of 7 degrees longitude by 2 degrees latitude. In the western parts of Austria an increase of warm and wet climate has occurred, whereas during the same period in the East an increase of warm and dry conditions has occurred. An even larger variety of spatially different trends appears concerning seasonal evolution. The question of climate change cannot be answered in the same way when taking into account larger regions and not only temperature but also other climatic elements.

COMPTEL results on the 1.809 MeV gamma-ray line from the Galactic-center region

The COMPTEL experiment on the Compton Gamma-Ray Observatory is designed to image celestial gamma radiation in the energy range from 0.75–30 MeV within a field of view of 1 steradian. It can locate stronger point sources with an accuracy better than 0.5° and is capable of mapping diffuse emission as well. The Galactic-center region was observed by COMPTEL for several 2-week periods in 1991/1992. These observations show evidence for 1.8 MeV line emission along the Galactic disk (attributed to radioactive 26Al), extending over at least 40 degrees in longitude.

Latitudinal and insular variation of skull size in crab-eating macaques (primates, Cercopithecidae: Macaca fascicularis).

Macaca fascicularis is broadly distributed in Southeast Asia across 30 degrees of latitude and 35 degrees of longitude (Indochinese Peninsula, Isthmus of Kra, Malay Peninsula, Greater and Lesser Sunda Islands, Philippine Islands, and numerous small, neighboring islands). The range is divisible into 1) a core area comprised of mainland Southeast Asia, Borneo, Sumatra, and Java (large land masses interconnected during the last glacial maximum, 18,000 B.P.); 2) shallow-water fringing islands, which are smaller islands connected to the core area during the last glacial maximum; and 3) deep-water fringing islands, which are peripheral islands not connected to the core area during the last glacial maximum. Skull length was used to study effects of latitude and insularity on patterns of size variation. The data are from 802 adult M. fascicularis specimens from 140 core-area localities, 63 shallow-water islands, and 29 deep-water islands. Sex-specific polynomial regressions of skull length on latitude were used to describe skull length variation in the core area. These regressions served as standards for evaluating variation among samples from shallow-water and deep-water islands. The core area exhibits Bergmannian latitudinal size clines through most of the species range. Thus, skull length decreases from about 8 degrees S (Java) to the equator (Sumatra and Borneo), then increases as far north as about 13 degrees N (Isthmus of Kra). Farther north, to the northernmost Indochinese localities at about 17 degrees N, skull length in M. fascicularis decreases with increasing latitude, contrary to Bergmann's rule. Latitudinal size variation in shallow-water fringing islands generally parallels that in the core area. However, skull length tends to be smaller than in the core area at similar latitudes. Deep-water fringing islands are markedly more variable, with relatively small specimens in the Lesser Sunda Islands and relatively large specimens in the Nicobar Islands. These analyses illustrate how a primate species may vary in response to latitudinal temperature variation and to isolation.

Images of Excited H 3 + at the Foot of the Io Flux Tube in Jupiter's Atmosphere

The electrodynamic interaction between lo and the Jovian magnetosphere drives currents to and from the planet's ionosphere, where H(3)(+) emission is excited. Direct images of this phenomenon were obtained with the ProtoCAM infrared camera at the National Aeronautics and Space Administration's 3-m Infrared Telescope Facility. The emissions are localized to the instantaneous foot of the lo flux tube, approximately 8 degrees equatorward of the more intense auroral H(3)(+) emission associated with higher magnetic latitudes. The foot of the lo flux tube leads that of (undisturbed) model magnetic field lines passing through lo by 15 degrees to 20 degrees in longitude and is less visible in the northern hemisphere at longitudes where the surface magnetic field strength is greatest. These data favor the unipolar inductor model of the lo interaction and provide insight into the source location and generation of Jovian decameter radio emission.