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.

Variation in Size and Location of the 300 mb North Circumpolar Vortex Between 1963 and 1975

Abstract: The time variation in size and location of the 300 mb north circumpolar vortex has been estimated from mean monthly polar stereographic maps for the years 1963–75, both by planimetering the area north of height contours in the main belt of westerlies and by determining the colatitude of these contours at 30° longitude intervals and squaring the average value. It is shown that the vortex areas determined by the two independent techniques are in excellent agreement, but that the vortex-center locations (based on equalization of arms) determined by the two techniques are in only fair agreement. The change in vortex area appears mainly to reflect a change in mean tropospheric temperature, but with some modification caused by a change in mean surface pressure in temperate latitudes. Since 1970 the yearly averaged vortex area has increased by almost 2%, but that increase apparently ended in 1975, suggesting that the cooling in north temperate latitudes has also ended. During this same five-year period ...

Positive ionospheric storm effects at Latin America longitude during the superstorm of 20–22 November 2003: revisit

Abstract: . Positive ionospheric storm effects that occurred during the superstorm on 20 November 2003 are investigated using a combination of ground-based Global Positioning System (GPS) total electron content (TEC), and the meridian chain of ionosondes distributed along the Latin America longitude of ~280° E. Both the ground-based GPS TEC and ionosonde electron density profile data reveal significant enhancements at mid-low latitudes over the 280° E region during the main phase of the November 2003 superstorm. The maximum enhancement of the topside ionospheric electron content is 3.2–7.7 times of the bottomside ionosphere at the locations of the ionosondes distributed around the mid- and low latitudes. Moreover, the height of maximum electron density exceeds 400 km and increases by 100 km compared with the quiet day over the South American area from middle to low latitudes, which might have resulted from a continuous eastward penetration electric field and storm-generated equatorward winds. Our results do not support the conclusions of Yizengaw et al. (2006), who suggested that the observed positive storm over the South American sector was mainly the consequence of the changes of the bottomside ionosphere. The so-called "unusual" responses of the topside ionosphere for the November 2003 storm in Yizengaw et al. (2006) are likely associated with the erroneous usage of magnetometer and incomplete data.

Solar wind spatial structure: The meaning of latitude gradients in observations averaged over solar longitude

Abstract: The three-dimensional structure of the solar wind is often studied by searching for solar latitude variations in observed physical properties that have been averaged over solar longitude. The effects of longitude averaging are examined here by using general qualitative arguments and quantitative calculations for a simple class of assumed spatial variations in the solar wind speed. We show that unless the solar wind spatial structure is simply organized about the solar equator, its presence is extremely difficult to infer from longitude averages unless the observations extend to very high solar latitudes. Thus the absence of semiannual variations in ecliptic observations or the absence of large latitude gradients in radio scintillation or comet tail results do not constitute evidence against the presence of strong spatial variations (or large spatial gradients) in the solar wind.

An Observational Investigation of Spatiotemporally Contiguous Heatwaves in China From a 3D Perspective

Abstract: Understanding the evolution of heatwaves is important for their prediction, mitigation, and adaptation. While most studies focused on either their temporal variability at individual station (or grid point) or the spatial variation over fixed durations, their daily joint evolution over space and time remains largely unexplored. Here, we investigate multi-dimensional characteristics of spatiotemporally contiguous heatwaves across China during 1961–2018 using observational data from a 3D perspective (i.e., latitude×longitude×time). Results obtained by the 3D identification show that large contiguous heatwaves in China exhibit distinct characteristics in different geographical locations and time periods. Heatwaves in northern areas prefer to move from west to east at a faster speed, persist longer, and have greater extent and intensity than southern heatwaves, which are generally originated from the east and move westward. It is also found that contiguous heatwaves are growing in frequency, magnitude, areal extent, duration, and traveling distance across China.