Complex study of characteristics of a Cb cloud developing over the Arabian Peninsula under high dew point deficit in the atmosphere. Part 1. Field observations and numerical modeling

Basing on airmass motion trajectory calculations over the Arabian Peninsula on April 10, 2008, it can be assumed that in the lower and middle troposphere, zones with increased air moisture exist due to air inflow from the Red Sea. As a result, mesoscale volumes of dry and moist air are neighboring, though large-scale field is comparatively homogeneous with low humidity. In the mesoscale zones, intense thunderstorm and hailstorm Cb clouds developed, whose characteristics and evolution are studied in the paper. Continuous radar observations of the clouds are carried out during 5 hours. Numerical simulation of the cloud evolution is performed with nonstationary 1.5-dimensional model. It is noted that under the mentioned atmospheric conditions, in the area under consideration, heavy rain and hail from the Cb clouds are observed. The main factors of their origination are high thermal instability of the atmosphere and moist air inflow from outside.     

The Effect of the Horizontal Dimensions of Inland Water Bodies on the Thickness of the Upper Mixed Layer

Water Resources - The effect of the horizontal dimensions of inland water bodies (lakes and reservoirs) on the vertical mixing processes is studied. We consider a three-dimensional hydrostatic...     

Models of Climate,Geophysical Boundary Layers,and the Active Land Layer: In Memory of V. N. Lykosov

Izvestiya, Atmospheric and Oceanic Physics - This paper is dedicated to the memory of Vasily Nikolaevich Lykosov, a prominent Russian scientist and a specialist in the field of mathematical...     

Moderately compact helix antennas with cutoff patterns for millimeter RTK positioning

GPS Solutions - Helical antennas have been developed that feature a cutoff pattern and are suitable for practical positioning at millimeter level. The antennas are in the form of a tube with...     

Complex study of characteristics of a Cb cloud developing over the arabian peninsula under conditions of high dew point deficit in the atmosphere. Part 2. Analysis of the meteosat data

Development of a long-living Cb cloud in the desert part of Saudi Arabia on April 10, 2008 is analyzed. Continuous satellite and radar observations of the cloud are carried out during five hours. Numerical modeling of the cloud is performed using a nonstationary 1.5-dimensional model. Data on the Cb cloud and its anvil development dynamics are obtained. It is shown that the anvil characteristics differ significantly in the zone of its formation directly over the cloud and when moving away from it. It is pointed out that the radar underestimates the anvil sizes. Estimation of precipitation rate from the cloud under study by means of satellite and radar measurements is compared against the results of numerical modeling. It is found that precipitation rate could reach 100 mm/h. The radar estimates of the precipitation rate are significantly overstated, which is, in this case, due to presence of large hail particles.     

Multipath mitigation by conventional antennas with ground planes and passive vertical structures

An antenna ground plane (GP) plays a major role in the mitigation of multipath coming from underneath the antenna. A distinct trend in user antenna size and weight reduction has been observed during recent years. With this focus in mind, an overview of conventional flat conductive and impedance GP is provided. Results of modern developments of passive vertically stacked structures are discussed. The possibility of obtaining a reasonable level of multipath mitigation with vertical structures of several centimeters is shown.     

Avdeevite,a Na-Dominant Alkali Beryl: Determination as Valid Mineral Species and New Data

Geology of Ore Deposits - Abstract—This paper describes the first Na-dominant member of the beryl group, named avdeevite. The sample, which became its holotype, was found in a granitic...     

On the Applicability of Similarity Theory for the Stable Atmospheric Boundary Layer over Complex Terrain

Micrometeorological measurements in the atmospheric boundary layer over a hilly forest terrain have been made on a meteorological tower at several levels from the forest canopy top to a height that exceeds the height of trees almost seven times. A semiempirical length scale depending on the local topography features and the underlying surface type has been proposed and calculated. This scale has been shown to allow the universal functions of the Monin–Obukhov similarity theory to be corrected for a stable atmospheric boundary layer over complex terrain without substantial modification when compared to the universal functions over a homogeneous surface with small roughness elements. This approach can be used to refine the methods for calculating turbulent momentum fluxes from profile measurements over spatially inhomogeneous landscapes.     

Complex use of satellite radiometric,surface radar,and cloud numerical modeling data for controlling the modification works aiming to prevent precipitation in Peterhof

Results are presented of complex study of the clouds during the modification works aiming to prevent precipitation. To estimate the modification effect, a new technique is presented based upon comparison of the IR-radiometer measurements data, from the Meteosat satellite, on radiation temperature of the clouds after modification and those in natural development cycle. It is shown that for the case under study, radiation temperature increase is observed in the pixel corresponding to the city in which precipitation should be prevented.