PV morphology of a frontal-wave development

Summary A case study is performed of a frontal-wave development on a trailing cold front in the Atlantic. The data base comprises principally the analysis and forecast fields of the global operational weather prediction model of the ECMWF, and the development itself is viewed from a potential vorticity (PV) perspective. It is shown that the ambient atmosphere contained three distinct and salient PV features: at the surface a frontal baroclinic zone; in the lower troposphere a co-aligned, moisture laden elongated band (2000 km long and 400 km wide) of enhanced PV; and at upper-levels a richly structured, southward extending PV pool. In the developments first phase a large-scale undulation of the surface frontal zone was accompanied by an in-phase movement of the upper-level anomaly. In a second phase two low-level wave features developed around 1000 km apart, and the resulting wave depressions were accompanied by a distortion of the baroclinic zone and the break-up of the low-level PV-band. In the subsequent mature phase the dominant secondary cyclone attained 500 km scale in the horizontal and acquired a coherent PV structure in the vertical.A PV-based diagnostic analysis provides evidence of both the self development of the PV features and their synergetic interplay. It also forms the basis for a comparison of the event with traditional and recent hypotheses for frontal-wave development.On the basis of the diagnosed relationship between the customarily depicted surface frontal-wave cups and the low-level PV-band, it is suggested that the segmentation of the latter provides a useful tool for monitoring and forecasting secondary developments. Also in the context of numerical weather prediction brief consideration is given to the sensivity of the frontal-wave development and structure to the spatial resolution of the associated forecast model and the specification of the initial fields.With 12 Figures     

The International Radiation Symposium 2016

正1.Overview The 2016 International Radiation Symposium,a joint venture between the IRC(International Radiation Commission)and IAMAS(International Association of Meteorology and Atmospheric Sciences),took place at the University of Auckland from April 16th to 22nd.The wide scope of atmospheric radiation research was apparent,with focuses rang-     

Photogrammetric measurements of Olympus Mons on Mars

Mariner 9 took many pictures of the giant Olympus Mons during its year in orbit around Mars. Control points have been identified on the top of Olympus Mons, on the volcanic shield, and on the surrounding plains, and their locations have been measured on the television pictures. These measurements were used to compute the aerographic coordinates and the planetary radii of the points. The radii at some of the points were derived from radar elevation measurements and from radio occultation measurements. The mountain rises about 21 km above its base.