ALBERT

Description: We present a high-resolution tomographic image in the upper mantle for the Hainan plume determined by using both local and teleseismic data. The arrival-time data from teleseismic events are measured precisely from seismograms recorded by nine permanent seismic stations in Hainan island and Leizhou peninsula. Our results show that striking low-velocity (low-V) anomalies of up to −5% in the crust and −2% in the mantle are visible under the Hainan hotspot from the surface down to 250 km depth. The Hainan plume is imaged as a continuous, NW–SE tilting, low-V column with a diameter of about 80 km. Given the denser data coverage and finer parameterization, our result represents a significant improvement with respect to earlier, regional and global tomographic studies. Such an inclination of the Hainan plume can be explained by numerical simulations. The tilted plume conduit in the upper mantle could be associated with the subduction of oceanic plates, especially the Philippine Sea plate, and the extrusion of the Eurasian plate. Most likely, the tilted plume conduit has buoyantly risen from the lower mantle.

Description: The Convective Storm Initiation Project (CSIP) is an international project to understand precisely where, when, and how convective clouds form and develop into showers in the mainly maritime environment of southern England. A major aim of CSIP is to compare the results of the very high resolution Met Office weather forecasting model with detailed observations of the early stages of convective clouds and to use the newly gained understanding to improve the predictions of the model. A large array of ground-based instruments plus two instrumented aircraft, from the U.K. National Centre for Atmospheric Science (NCAS) and the German Institute for Meteorology and Climate Research (IMK), Karlsruhe, were deployed in southern England, over an area centered on the meteorological radars at Chilbolton, during the summers of 2004 and 2005. In addition to a variety of ground-based remote-sensing instruments, numerous rawin-sondes were released at one- to two-hourly intervals from six closely spaced sites. The Met Office weather radar network and Meteosat satellite imagery were used to provide context for the observations made by the instruments deployed during CSIP. This article presents an overview of the CSIP field campaign and examples from CSIP of the types of convective initiation phenomena that are typical in the United Kingdom. It shows the way in which certain kinds of observational data are able to reveal these phenomena and gives an explanation of how the analyses of data from the field campaign will be used in the development of an improved very high resolution NWP model for operational use.