Longitude

About: Longitude is a research topic. Over the lifetime, 2260 publications have been published within this topic receiving 54988 citations. The topic is also known as: angle of longitude.

Global morphology of nitric oxide in the lower E region

Abstract: Measurements of nitric oxide at 105 km by the ultraviolet nitric oxide experiment on Atmosphere Explorer C are presented. The amount of nitric oxide in the lower E region is shown to depend on latitude, longitude, and magnetic activity. Near the equator the density at the peak of the NO layer is typically about 2 x 10 to the 7th power/cu cm and varies little with longitude or magnetic activity, except during major storms. At high latitudes (up to 68 deg geographic latitude), peak densities are typically 2 or 3 times larger and much more variable. A longitudinal dependence is found in both geographic and geomagnetic coordinates, with minimum densities found near 45 deg E geomagnetic longitude and maxima near 135 deg W geomagnetic longitude. At 40 deg dip latitude the half amplitude is about 30%.

Wild Cantor attractors exist

Abstract: T I lHE scientific community dealing with earth characteristics, marine and air navigation, and modern concepts of national defense is vitally concerned with longitudinal ties between continents. Expanded interest in modern geodesy has resulted particularly from research programs in developing intercontinental guided missiles and earth-circling satellites. The art of navigation has always been the most practical application of longitude, but in this the art does not require any high degree of precision. Concomitant to the age of exploration and rapid expansion of water-borne traffic was the urgent demand for a means of determining longitude at sea. Beginning with Harrison's chronometer, steady refinements were made until modern times, when continental ties are possible with the aid of telegraph and radio. Aside from navigational considerations, several purely scientific requirements involve the precise determination of longitude with reference to a standard meridian, such as Greenwich. The astronomer requires an accurate position for the time coordination of world-wide astronomical observations; the geophysicist needs longitudes of the highest precision in his studies of the drift of continents; and, finally, the geodesist desires to place all triangulation datums as closely as possible in their proper relation one with the other. Longitudinal studies, no matter how localized in place or how distant in time, have an important bearing on the subject. In celebrating the sesquicentennial of the United States Coast and Geodetic Survey during 1957, it is fitting to recall the Survey's contribution to the establishment of precise longitude in the United States. Early in the history of this bureau the need became apparent for a precise tie between some main-scheme triangulation stations in the United States and the meridians of any and all of the European observatories. The Harvard Observatory at Cambridge was adopted for the point of origin in the United States and in due time was tied to Greenwich by the method discussed in this paper. The second superintendent of the Coast Survey, Alexander Dallas Bache, was well aware of the difficulties other nations had encountered in fixing the

Latitudinal, vertical, and seasonal variations of C1‐C4 alkyl nitrates in the troposphere over the Pacific Ocean during PEM‐Tropics A and B: Oceanic and continental sources

Abstract: [1] We present concentration distributions of C1-C4 alkyl nitrates observed during the NASA airborne campaigns Pacific Exploratory Mission (PEM) -Tropics A (September–October 1996) and PEM-Tropics B (March–April 1999). The total geographic range for PEM-Tropics A was 45°N–72°S latitude and 153°E–75°W longitude, and for PEM-Tropics B was 40°N–36°S latitude and 149°E–75°W longitude. The maximum altitude for these missions was 12 km. These experiments provide the most extensive set of tropospheric measurements collected to date over the tropical Pacific Ocean. We observed high methyl nitrate (MeONO2, CH3ONO2) mixing ratios (approximately 50 pptv) at low altitudes in a latitude band between 8°N to 13°S stretching across the equatorial Pacific, illustrating the oceanic source of MeONO2. This source may be associated with the high-nutrient, low-chlorophyll character of equatorial Pacific waters. We discuss MeONO2 and ethyl nitrate (EtONO2, C2H5ONO2), whose abundance is dominated by equatorial oceanic sources, 2-Propyl nitrate (2-PrONO2, 2-C3H7ONO2), which has significant oceanic and northern hemispheric (NH) sources associated with urban/industrial hydrocarbon emissions, and 2-butyl nitrate (2-BuONO2 2-C4H8ONO2), which has mostly NH sources. PEM-Tropics A and B resulted in remarkably similar equatorial mixing ratios. The excellent correlations between MeONO2 and the other alkyl nitrates in this region produced comparable correlation slopes between the two expeditions. By contrast, NH air masses influenced by urban/industrial emissions typically exhibited much lower MeONO2:EtONO2, MeONO2:2-PrONO2, and MeONO2:2-BuONO2 ratios. These relationships can be useful as a diagnostic of air mass origin. North of 10°N, the springtime PEM-Tropics B mixing ratios of C2-C4 alkyl nitrates were many-fold higher at low-mid altitudes than for late summer PEM-Tropics A, consistent with strong continental outflow of NMHC precursors during spring.

Depth, distribution, and density of CO2 deposition on Mars

Abstract: Observations by the Mars Orbiter Laser Altimeter have been used to detect subtle changes of the polar surface height during the course of seasonal cycles that correlate with the expected pattern of CO2 deposition and sublimation. Using altimetric crossover residuals from the Mars Orbiter Laser Altimeter, we show that while zonally averaged data capture the global behavior of CO2 exchange, there is a dependence of the pattern on longitude. At the highest latitudes the surface height change is as high as 1.5–2 m peak to peak, and it decreases equatorward. Decomposition of the signal into harmonics in time allows inspection of the spatial pattern and shows that the annual component is strongly correlated with the residual south polar cap deposits and, to a lesser extent, with the north polar cap. In the north, the second harmonic (semiannual) component correlates with the location of the ice deposits. The phases of the annual cycles are in agreement with observations by the Thermal Emission Spectrometer of the timing of the annual disappearance of CO2 frost from the surface at the high latitudes. At lower latitudes, frost sublimation (“Crocus date”) predates the mean depositional minima, as expected. These global-scale, volumetric measurements of the distribution of condensed CO2 can be combined with measurements of the deposited column mass density derived from the Neutron Spectrometer on board Mars Odyssey to yield an estimate of the density of the seasonally exchanging material of 0.5 ± 0.1 g/cm^3. These constraints should be considered in models of the Martian climate system and volatile cycles.