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.

Evidence for large-scale velocity features on the sun

Abstract: Giant velocity features on the solar surface are seen in line-of-sight velocity data from the Mount Wilson magnetograph Velocity amplitudes around 40 m/s are seen in features with dimensions about 15 deg in latitude and 30-60 deg in longitude These features are associated with solar activity The largest such feature accompanied the largest complex of activity in this interval, lived for about 16 rotations, and predated the first magnetic fields in the area by about two rotations A general pattern of upward motion at the equator is seen, and motions away from the earth at higher latitudes could represent a meridional flow toward the poles of the order of 20 m/s

Cosmic ray decreases and solar wind disturbances during late October 1989

Abstract: We describe the interplanetary phenomena (energetic particles, solar wind plasma, and magnetic field) seen at Interplanetary Monitoring Platform 8 (IMP 8) and at International Cometary Explorer (ICE), located 65 deg west of IMP 8, during the period October 19-31, 1989, when neutron monitors observed three ground level events originating in one active region when it was in the longitude range E09 deg to W57 deg. At least four shocks, associated with energetic particle enhancements, which can be attributed to a sequence of coronal mass ejections from the same active region, were seen at both spacecraft. An additional shock was observed only at ICE late in this period when the active region was behind the west limb. Considering all the data (which unfortunately suffer from large gaps), it appears that the ejecta associated with the shocks were detected only when the spacecraft and solar source longitude were separated by less than 50 deg. The shocks extended over a greater range of longitudes. The cosmic ray record at Earth is consistent with this picture such that only the first two shock-associated cosmic ray decreases had the signature expected for intercepting ejecta material. This same time period was also examined by Bavassano et al. (1994). However, we do not agree with their conclusion that 'magnetic clouds' extending at least 75 deg from the source longitude were present.

Comparisons of magnetic anomalies of lithospheric origin measured by satellite and airborne magnetometers over western Canada

Abstract: Crustal magnetic anomaly data from the OGO 2, 4 and 6 (Pogo) satellites are compared with upward-continued aeromagnetic data between 50 deg -85 deg N latitude and 220 deg - 260 deg E longitude. Agreement is good both in anomaly location and in amplitude, giving confidence that it is possible to proceed with the derivation and interpretation of satellite anomaly maps in all parts of the globe. The data contain a magnetic high over the Alpha ridge suggesting continental composition and a magnetic low over the southern Canada basin and northern Canadian Arctic islands (Sverdrup basin). The low in the Sverdrup basin corresponds to a region of high heat flow, suggesting a shallow Curie isotherm. A ridge of high field, with two distinct peaks in amplitude, is found over the northern portion of the platform deposits and a relative high is located in the central portion of the Churchill province. No features are present to indicate a magnetic boundary between Slave and Bear provinces, but a trend change is evident between Slave and Churchill provinces. South of 60 deg latitude a broad magnetic low is located over very thick (40-50 km) crust, interpreted to be a region of low magnetization.

Longitudinal variations in planetary wave activity in the equatorial mesosphere

Abstract: Zonal and meridional winds in the equatorial mesosphere and lower thermosphere (65–98 km) measured at two sites separated by 94° in longitude are used to study the zonal structure of planetary-scale waves. The data were obtained with MF radars located at Pontianak (0°N, 109°E)and Christmas Island (2°N, 157°W). The data at Christmas Island were collected from January 1990 to December 1997 and the observations at Pontianak were made from November 1995 to July 1997. Power spectral techniques are used to study the amplitude and frequency variations of long-period oscillations as a function of height and time. A mean climatology of these variations taken from years 1990–1997 is presented. Strong peaks in zonal and meridional winds are found at tidal periods and for the quasi 2-day wave. Zonal spectra exhibit considerable power at periods of 3–10 days, with transient oscillations with periods near 3.5 day and 6.5 days being especially prominent. The 6.5-day wave is particularly strong during April and September. Examination of the phase differences obtained from cross-spectra between the two stations show that the 6.5-day wave is westward propagating with zonal wavenumber 1, while the 3.5 day wave is eastward propagating with wavenumber 1. The 6.5-day wave is identified as a manifestation of an unstable mode, while the 3.5-day wave is identified as an ultrafast Kelvin wave. There are significant longitudinal variations in the amplitudes and inferred momentum fluxes of the 3.5-day wave, amplitudes being larger in the Asian region than in the central Pacific.

Statistical analysis of 26 yr of observations of decametric radio emissions from Jupiter

Abstract: Jupiter is a complex and at the same time very powerful radio source in the decameter wavelength range The emission is anisotropic, intrinsically variable at millisecond to hour timescales, and also modulated by various external processes at much longer periods, ranging from similar to 10 h to months or years (including Jovian day and year, solar activity and solar wind variations, and for ground-based observations, terrestrial day and year) As a consequence, long-term observations and their statistical study have proved to be necessary for disentangling and understanding the observed phenomena We have built a database from the available 26 yr of systematic, daily observations conducted at the Nancay Decameter Array and recorded in digital format This database contains all observed Jovian decametric emissions, classified with respect to the time-frequency morphology, their dominant circular polarization, and maximum frequency We present the results of the first statistical analysis of this database We confirm the earlier classification of Jovian decameter emissions in Io-A, -A', -B, -C, -D and non-Io-A, -B, -C types, but we also introduce new emission types (Io-A '' and Io-B') and precise and characterize the non-Io-D type We determine the contours of all emission types in the CML Phi(Io) plane (Central Meridian Longitude in Jupiter's System III coordinates versus Io Phase), provide representative examples of their typical time-frequency patterns, and the distribution of emission's maximum frequency as a function of Lambda(Io) (Io's Longitude) Finally, we present a statistical analysis of the distributions of the occurrence rate, duration, intensity and polarization for each emission type non-Io-DAM appears to be related to small-scale, possibly bursty auroral structures