Synoptic and Mesoscale Analysis of Satellite Images

This course will teach you how to operationally parse a satellite image in synoptic and mesoscale conceptual models. Analysing a satellite image in terms of conceptual models is the best way to learn to retrieve a 3D- or even 4D (with time being the fourth dimension) mental weather picture.

If you chose to do this course on self study, allow yourself to reserve a longer time period, to provide enough possibilities to practise with the interpretation of satellite images for different meteorological situations using ePort.

The course is designed for operational forecasters and meets the standards identified by WMO.

Lecture 1: Satmanu


Presented by Ab Maas

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.

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Lecture 2: Frontal Structures


Presented by Ab Maas

A weather front is a boundary separating two masses of air of different temperatures and humidity, thus different densities. They are often connected to a significant phenomena such as showers and thunderstorms, and more generally to instability of the atmosphere. This lecture is based on two frontal structure types - Cold and a Warm font.

In Satmanu there are five types or conceptual models related to Cold front; Arctic Cold Front, Cold Front (divided into Ana and Kata types), Cold Front in Cold Advection, Cold Front in Warm Advection and a Split front. Among Warm Front features there are; Detached Warm Front, Warm Front Band and a Warm Front Shield. In Satrep manual there are five chapters on each of above mentioned features; Cloud Structure In Satellite Images, Meteorological Physical Background, Key Parameters, Typical Appearance In Vertical Cross Sections an a Weather Events. Ab Maas, will try to introduce these chapters to you, dealing with above mentioned types of Cold and Warm fronts.

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Lecture 3: Occlusions


Presented by Veronika Zwatz-Meise

This lecture is somehow extension of previous in this Satellite course, and is given by Dr. Veronika Zwatz-Meise. She is speaking about Occlusions. There are five features connected to them and these are; Back-Bent Occlusion, Cold Air Development, Instant Occlusion, Cold Conveyor Belt Type and a Warm Conveyor Belt Type of Occlusion.

Presentation is constructed in a way that first there is an explanation of how do occlusion cloud bands look like in different satellite images. Question of processes that take place in the troposphere that lead to what we see in satellite images is also discussed. After that meteorological numerical parameters that describe the occlusion processes in a best way are observed (both on isobaric and isentropic surfaces). And at the end answer to a question "Which special developments at/with occlusion cloud bands take place during their life cycle?" are answered.

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Lecture 4: Frontal Substructures


Presented by Andreas Wirth (ZAMG)

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.

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Lecture 5: Cyclogenesis


Presented by Barbara Zeiner (ZAMG)

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.

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Lecture 6: Convective Cloud Features in typical synoptic situations


Presented by Frans Debie (KNMI)

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.

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Lecture 7: Polar Lows


Presented by Justyna Wodziczko (met.no)

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.

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Lecture 8: Convergence lines over Sea and Lakes


Presented by Jan Hemink (KNMI)

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.

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Lecture 9: Extremely strong convection in Lithuania


Presented by Viktorija Grusaite (LHMS)

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 tunderstorms; 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 -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.

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Lecture 10: Rapid Cyclogeneisis or Medicane?


Presented by Teodoro la Rocca (CNMCA)

This case study took place in Mediterranean basin form 7th to 8th November 2011, with some interesting weather phenomena occurred there. It is show 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 phenomena can not be classified as Tropical cyclone nor the Rapid cyclogenesis. The case is treated only by a synoptic point of view, using Meteosat 9 satellite images and ECMWF numerical fields from ePort (Satrep) web site and other graphical elaborattions with Metview.

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