Satellite skills and knowledge for operational meteorologist
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Presentation on SAR image analysis and on the interpretation of oceanic and atmospheric phenomena, with examples of signatures of downbursts, convective cells and sea/land breezes. Also, the retrieval of high resolution wind speed with SAR will be addressed.
Synthetic-aperture radar (SAR) is a form of radar whose defining characteristic is its use of relative motion between an antenna and its target region to provide distinctive long-term coherent-signal variations that are exploited to obtain finer spatial resolution than is possible with conventional beam-scanning means. It originated as an advanced form of side-looking airborne radar (SLAR).
SAR is usually implemented by mounting, on a moving platform such as an aircraft or spacecraft, a single beam-forming antenna from which a target scene is repeatedly illuminated with pulses of radio waves at wavelengths anywhere from a meter down to millimeters. The many echo waveforms received successively at the different antenna positions are coherently detected and stored and then post-processed together to resolve elements in an image of the target region.
Current airborne systems provide resolutions to about 10 cm, ultra-wideband systems provide resolutions of a few millimeters, and experimental terahertz SAR has provided sub-millimeter resolution in the laboratory.
SAR images have wide applications in remote sensing and mapping of the surfaces. In this presentation the applications for monitoring the ocean surfaces are discussed.
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.
This one hour presentation takes focus on the characteristics of the product files that are produced and distributed by LSA SAF.
This one-hour presentation takes focus on the characteristics of the product files that are produced and distributed by LSA SAF. The structure of the files is explained and freeware tools are presented. All the relevant information is given for the obtaining LSA SAF products. More general product information is given for documentation and file structure of data. Also, this session is explaining how to use Quick visualization by means of HDFView, GIS tools for visualization and analysis (Quantum GIS, GRASS GIS and ILWIS) and tool for georeferencing LSA SAF products. At the end of presentation there are words about how to use Python scripting for building custom scripts or programs for accessing and manipulating Land SAF data.
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.
Evapotranspiration is a parameter closely related to vegetation state and stress. This session will show how this quantity is obtained within the LSA SAF.
Evapotranspiration is a parameter closely related to vegetation state and stress. This session will show how this quantity is obtained within the LSA SAF. Evapotranspiration is estimated using a land surface model forced with radiation and vegetation variables obtained from SEVIRI measurements. Very interesting Resistance scheme of this model is nicely explained using deviding image pixels into \'tiles\' of homogeneous vegetation types. Input and output of this model is also mentioned. Presentation is showing validation and incomparison of results together with possible applications of it.
Presentation giving an overview on the use of satellite data, particularly that from Meteorological satellites, for monitoring vegetation cover and properties.
The current presentation gives an overview on the use of satellite data, particularly that from Meteorological satellites, for monitoring vegetation cover and properties. Some basic physical principles are first presented and then some RGB images are shown, allowing to identify different features in the surface of the earth. Further information on vegetation is given by a wide range of empirical indices, from which one of the most used is the NDVI. There are however some disadvantages on using such vegetation indices. Other parameters more related to vegetation properties and health than these conventional empirical indices are available from the LSA SAF. These are the Fractional Vegetation Cover (FVC), the Leaf Area Index (LAI) and the Fraction of Absorbed Photosyntetically Active Radiation (fAPAR). The algorithm rationale for deriving such parameters is explained and some validation results are presented. Finally, the use of these products in several applications is shown.
Discussion is held on various techniques of mapping burnt areas from remotely sensed data, describing the main sources of errors and strategies to overcome them.
Discussion is held on various techniques of mapping burnt areas from remotely sensed data, describing the main sources of errors and strategies to overcome them. Focus of first part of this session is so-called Fire Detection and Monitoring (FD&M) product, which provides continuous monitoring of fire activity over Africa and Europe. This product relies on Fire Detection Algorithm called FiDAlgo (based on so-called contextual algorithms), is an operational procedure that allows active fire detection in near-real-time and is based on information from Meteosat-9, i.e. SEVIRI instrument.
The second part will present applications to the analysis of burnt scars and vegetation recovery, with case studies for the Iberian Peninsula. Operational product for tracking burnt areas LSA-SAF still doesn't have, but presentation gives perspective of rising such. Very simple model for post-fire vegetation recovery is presented and are shown correlations between post fire vegetation recovery dynamics and severity of fire damage.
This presentation gives various applications of LSA SAF radiation products that we can find in four production areas for MSG satellite.
This presentation gives various applications of LSA SAF radiation products that we can find in four production areas for MSG satellite; Europe, Northern Africa, Southern Africa and Southern America. Firstly, variability (both seasonal and spatial) that we can find in albedo fields are discussed together with signatures, or features you can look for in LST fields. Relations between LST and vegetations, which comes from the fact that vegetation is controlling temperature by means of evapotranspiration are also shown here. Another application of radiation product is diagnose of various models via land surface temperature. At the end of presentation there are some words about long-wave and shot wave surface radiation budget, which are strongly influenced by clouds at seasonal scale.