Identify and interpret atmospheric phenomena
The EUMETCAL High Impact Weather group addressed a series of convective events over Europe during the summer 2010.
The EUMETCAL High Impact Weather group addressed a series of convective events over Europe between 5 and 9 August 2010. This events affected many countries from southern areas - Mediterranean/Balkans - to northern areas - Baltic/Scandinavia. In the 30 minute presentation the group analyzed the events, combining the analysis of convection, namely by satellite, with the impacts perspective.
Presentation with results on the occurences of overshooting tops in convective clouds in relation to severe weather.
Presentation given during the Convection Week 2011 by Petra Mikus, a young researcher from the Croatian Meteorological and Hydrological Service DHMZ. The presentation presents results on the occurrences of overshooting tops in convective clouds in relation to severe weather in Austria, Slovenia and Croatia.
For knowing which processes are present in the atmosphere good interpretation of WV satellite images is needed. For gathering information about water vapor, SEVIRI instrument on board MSG satellite is scanning atmosphere in two channels in water vapor absorption band; 6.2 and 7.3 µm.
WV images are like a footprint of absorption of radiation by a water vapor, which is the main absorber in the atmosphere. Therefore it is clear that understanding of these images can tell us a lot about footprint of atmosphere itself and about processes in it. For knowing which processes are present in the atmosphere good interpretation of WV satellite images is needed.
For gathering information about water vapor, SEVIRI instrument on board MSG satellite is scanning atmosphere in two channels in water vapor absorption band; 6.2 and 7.3 µm. Among these two WV channels, the radiation in channel 6.2 µm is more easily absorbed by water vapor and has a larger information content. Thus is called primary WV channel and is broadly used in image format for weather analysis and forecasting based on synoptic scale interpretation. 7.3 µm channel can also be used in operational forecasting environment for detecting mid-level moisture features associated with low-level thermodynamic conditions. Presenter for this one hour lesson is Christo Georgiev, from Bulgarian National Institute of Meteorology and Hydrology.
Conceptual models are everywhere around us, even in our heads. Human brain as it is, can store lot of impressions but processing these informations can be a big problem.
Conceptual models are everywhere around us, even in our heads. Human brain as it is, can store lot of impressions but processing these informations can be a big problem. That is why we need conceptual models in everyday communication to know what do others even talking about. All the model data, satellite data, observations, radar data, etc. require good processing of one forecaster so he can cope with all this informations - that is where conceptual model fits in. Very chaotic processes in the atmosphere are today reduced to a smaller number of conceptual models, for the aim of better understanding of whole atmosphere. In this one hour presentation Ab Maas , is introducing manual of conceptual models called Manual of synoptic satellite meteorology (Satmanu). This project started in 1995 and until now there were more than 50 conceptual models described in it, still now maintenance and updating of new models is present. Some of the features and examples of conceptual models are brought in this lecture.
Presentation on the substructures in fronts and initial stages of cyclogenesis.
This one hour presentation on Frontal Structures, brought by Andreas Wirth from ZAMG, is following content of chapter called "Substructures in fronts and initial stages of cyclogenesis", from Satmanu manual. But not all features under this chapter will be discussed. Lecture starts with Front Decay and Front Intensification by Jet Crossing. These are two very similar conceptual models but they show the opposite effect. This is followed by Upper Wave and Wave. Presenter will show these two conceptual models together to see the differences or the common features between them. Finally, presentation finishes with Secondary Low Centres in Occlusion Cloud Bands, which is feature easy to detect and not very complicated conceptual model.
Presentation on Rapid Cyclogenesis and Instant Occlusion.
Two conceptual models from Satmanu manual are introduced by Barbara Zeiner from ZAMG; Rapid Cyclogenesis and Instant Occlusion. These are two kinds of cyclogenesis, but not the classical forms of an occlusion. In normal or classical occlusion there would be a broken wave in a polar front, but in this case we have somewhat different situation. In short, Rapid Cyclogenesis describes a very fast and intensive development of an Occlusion cloud spiral from a low level cloud head. Upper air processes are driving factors in such a development. On the other hand, Front intensification by jet crossing is development of thicker and mostly more convective cloud within a frontal cloud band in the left exit region of a jet streak during frontal crossing. All these processes in this lecture are supported by satellite images and lot of schematics from Satmanu Manual.
This lecture is about conceptual models connected to strong convective processes.
This lecture is about conceptual models connected to strong convective processes. For easier detection and understanding of these clusters, Key parameters are introduced. Most of times there is (Equivalent) Thickness (e.g between 1000 and 500hPa) given along with Potential (Wet Bulb) Temperature at 850 hPa, and together they present parameters for detection of warm areas in Troposphere suitable for convective processes. Low Level Convergence is a key parameter used for detection of areas of high convergence, thus triggering convective areas. Of course, Instability indices are given to track the areas of unstable atmosphere also suitable for cloud development. Some of the physical background and examples of convective processes is shown it this lecture, with help of Satmanu module and satellite images. Also one of the convective cloud features known as a Spanish Plume is descirbed, along with four main types of thunderstorms (Single call, Multicell cluster, Multicell line and Supercell). Presenter of this lecture is Frans Debie, from KNMI.
Polar Lows are generally characterized by a severe weather in form of a strong winds, showers and occasionally heavy snow, which had sometimes resulted in lost of lives, especially on the sea area.
Polar Lows are generally characterized by a severe weather in form of a strong winds, showers and occasionally heavy snow, which had sometimes resulted in lost of lives, especially on the sea area. Sometimes these systems are also connected with term Arctic Hurricane, which had been used for especially intense Polar lows. Compromising definition of Polar low is small, but fairly intense low in maritime regions. They are formed in cold air outbreaks, north of the polar front, mostly in the regions east of 0°E and south of 75°N. Favorable season for them is cold part of the year. By size, they are smaller than the ordinary synoptic lows (200-600 km) with the life-span typically around 18 hours, and with very intense change of weather. As it is said before, within these Polar lows very strong winds can occur (15-25 KT, max. 52 KT) so understanding of these systems is of a great safety (and other) importance. All these facts and very nice example of Polar lows are presented by Justyna Wodziczko, from Norwegian Meteorological Institute.
The intention of this case study lecture is to demonstrate the effect of an intensifying, marine cloud street (originated in continuing cold air advection over warm seawater) as a result of divergence and convergence at low levels over coastal regions and narrow straits.
The intention of this case study lecture is to demonstrate the effect of an intensifying, marine cloud street (originated in continuing cold air advection over warm seawater) as a result of divergence and convergence at low levels over coastal regions and narrow straits. Frictional convergence and high instability appear to be the most important aspects for intense line convection. Although the divergence at low altitudes was not always very clear depicted in this case the large-scale divergence patterns at higher levels, the extreme low temperatures and the left exit of the Polar Jet streak overhead appeared to have a major impact. As a result the marine cloud streets changed into active lines of hail and snow showers over sea and especially over land with quite a number of thunderstorms at time of the maximum temperature. The use of satellite imagery, surface and upper air weather charts almost simultaneously is of great help in detection and very short term weather forecasting (nowcasting). In very cold air objective instability indices, like Boyden, appear to be very helpful in forecasting low topped winter storms.
There are three types of thunderstorms; Single-cell, Multi-cell and Supercell. And they all need some ingredients like warm and moist air at low levels, cool and dry air at upper levels, upper level divergence and synoptic scale disturbance.
This presentation consist of several parts. It is starting with some words about basics of convective storms and then case study analysis are introduced, with weather charts, radio-sounding data and satellite images. There are three types of thunderstorms; Single-cell, Multi-cell and Supercell. And they all need some ingredients like warm and moist air at low levels, cool and dry air at upper levels, upper level divergence and synoptic scale disturbance. Squall lines, heavy rain and thunderstorms , mostly in the central part of Lithuania were reported at the night of 8th of August 2011. The strongest wind gusts reached even 30 m s-1 and exceeded the value of 60 m s-1 in the major parts of the country. Supercell also did the damage of €7.000.000 to a local forest, and even four casualties were suffered.
Land surface albedo quantifies the fraction of energy reflected by the surface of the Earth. As a corollary it then also determines the fraction of energy absorbed by the surface and transformed into heat or latent energy.
Land surface albedo quantifies the fraction of energy reflected by the surface of the Earth. As a corollary it then also determines the fraction of energy absorbed by the surface and transformed into heat or latent energy. Land surface albedo therefore is a key variable for characterising the energy balance in the coupled surface-atmosphere system and constitutes an indispensable input quantity for soil-vegetation-atmosphere transfer models. On the other hand, the down-welling surface short-wave radiation flux (DSSF) refers to the radiative energy in the wavelength interval [0.3 to 4.0 microns] reaching the Earth\'s surface per time and surface unit. It essentially depends on the solar zenith angle, on cloud coverage, and to a lesser extent on atmospheric absorption and surface albedo.
First presentation is devoted to an introduction of method retrievals for surface albedo and DSSF products that are implemented in framework of the LSA SAF in using MSG /SEVIRI observations. A second presentation will detail the validation exercise of these two LSA SAF operational products, which is based on inter-comparison with other satellite products, in situ measurements and outputs from NWP models.
Lecture on unusual cyclogenesis taking place in the Mediterranean basin on 7 and 8 November 2011.
This case study took place in Mediterranean basin from 7th to 8th November 2011, with some interesting weather phenomena occurred there. It is shown that the sequential cloudiness type bands were; not organized convective system in the first step, then Comma feature in the next step, deep convection and finally occlusion. Because of confusing weather features connected to it, this weather phenomenon can not be classified as Tropical Cyclone nor as Rapid Cyclogenesis. The case is treated only from a synoptic point of view, using Meteosat-9 satellite images and ECMWF numerical fields from ePort web site and other graphical elaborations with Metview.