Satellite Image Interpretation

This course starts with describing the characteristics of the various sensing channels available on Meteosat Second Generation (MSG). The limitation and the applications of each sensing wavelength will be lectured and in this respect also the importance of weighting functions will be explained. The course than continues by introducing the technique of enhancing satellite image and what benefits this can have in nowcasting.

A series of lectures is dedicated to which different MSG channels are often combined to produce rich RGB images which are directly linked to the relevant specific meteorological applications. Besides there will be a series of lectures in which different derived products from the Satellite Application Facilities (SAF) are introduced. These will include the Nowcasting SAF, Ocean and Sea Ice SAF and the Land SAF.

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 phenomena such as convection, fog and cyclogenesis.

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

Lecture 1: Solar Channels


Presented by Jose Prieto (EUMETSAT)

This one hour lecture, held by Jose Prieto, is covering topic of solar satellite channels, mostly from SEVIRI instrument on board MSG. Of all twelve channels form SEVIRI these are the first four, with central wavelengths of 0.3-1.1; 0.6; 0.8 and 1.6 µm, respectively.

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Lecture 2: IR Images


Presented by Jan Kanak (SHMU)

Overview and application of infrared channels presented by Jan Kanak. The scope for this 30 minutes lecture is to define origins of IR radiation and how it is measured by meteorological satellites. Thermal radiation wavelengths are spreaded in wide interval from basically 1 µm up to 1000 µm, but in this case interest is only in middle IR (3 - 8 µm) and long IR (8 - 15 µm) spectrum.

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Lecture 3: IR Enhancements


Presented by Martin Setvak (CHMI)

Image enhancement is a process of image modification or improvement of its quality, the aim of which is to achieve a more pleasing appearance of the final image. However, in science, the main goal for image enhancement is to increase the interpretability of the image to a human eye and brain, typically focusing on a certain feature carried by the image.

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Lecture 4: WV Images


Presented by Christo Georgiev (NIMH)

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.

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Lecture 5: CO2 and O3 absorption Channels and IASI


Presented by Xavier Calbet (EUMETSAT)

This lecture on absorption channels and IASI instrument on board MetOp satellite was held by Xavier Calbet from EUMETSAT. MetOp is LEO polar orbiting satellite that is spinning around Earthat at hight of approximately 800 km. IASI instrument is scanning atmosphere below him in mostly infra-red spectrum band, therefore it can detect emission/absorption of gases like CO2 and O3 quite good, due to their intrinsic physical properties. In that way you one can track these gases in the atmosphere and mark their spatial and temporal distribution.

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Lecture 6: Introduction to RGBs and Channel Differences; Natural Colour RGB; HRV RGB and Night Microphysics RGB


Presented by Jarno Schipper (ZAMG)

Powerpoint giving you an introduction on RGB imagery with the emphasis on its applications. Presentation continues with the benefits of channel differences (BTD) and an application to detect fog during night using the IR3.9 - IR10.8 BTD int he Night Microphysics RGB.

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Lecture 7: Microphysics RGBs - Convective Storms


Presented by Daniel Rosenfeld (Hebrew University of Jerusalem)

Convective clouds can be characterized by three cloud top properties that can be detected by satellites and represented by respective tree RGB components;

1. Visible brightness, reflecting more solar radiation for thicker clouds with more water and ice (associated with RED color on RGB composites)

2. Cloud particle size and phase (water or ice), having larger drops with greater depth (associated with GREEN color on RGB composites)

3. Temperature, lover for higher tops (associated with BLUE color in RGB composites).


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Lecture 8: Airmass RGB


Presented by Jarno Schipper (ZAMG)

Presentation by Jarno Schipper (ZAMG) on one of the most complex RGBs available for MSG – the Airmass RGB. The synoptic perspective of this RGB and the relation to upper/middle level features will be addressed.

Powerpoint..

Lecture 9: Nowcasting Applications


Presented by Maria Putsay (OMSZ)

This lesson, given by Maria Putsay from Hungarian Meteorological Service, is about derived products for nowcasting applications. Objectives of the Nowcasting SAF are development of Nowcasting products derived from MSG and Polar satellite systems, delivering of the SW Packages to users and User's support task through Help Desk. Two software packages for producing products for nowcasting purposes are SAFNWC/MSG (for geostationary satellites) and SAFNWC/PPS (for polar satellites) and the overview of these are given here. Products may be used in two ways; as an input to a program (e.g. to an objective meso-scale analysis or as intermediate product input to other products) and as an final image product for display at a forecaster's desk, or case studied. But the main aim is firs one mentioned. Also in this lecture applications of the NWC SAF products at the Hungarian Meteorological Service are discussed.

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Lecture 10: Fog


Presented by Herve leGleau (MF)

Because we don't know if the cloud observed from satellite is reaching ground or not, it is unrealistic to clam that we can identify fog only using satellite data. Therefore presenter of this lecture is not presenting fog mapping derived only from satellite. Instead he is revealing cloud products extracted from MSG SEVIRI satellite imagery using NWCSAF software, concentrating on the fog or low level clouds category. Lecture is starting with some basic information about SAF nowcasting. After that main features of SAFNWC/MSG cloud algorithms, CM a (cloud mask), CT (cloud type) and CTTH (cloud top temperature and height) are given, step by step with validation results. Also there are examples with fog or low-level clouds situations, including example of automatic use for fog risk mapping. This presentation is given by Herve Le Gleau from Meteo-Framce.

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Lecture 11: Dust and Mesoscale and Synoptic Scale Patterns


Presented by Jochen Kerkmann (EUMETSAT)

Dust is a global issue with it's good and also less good sides. There are hundreds or even thousands of places on Earth where the dust can be lifted, nevertheless you need to have a dust source to create a dust outbreak. And these are indeed two needed ingredients for lifting dust in the air that must come together; strong surface winds (requires about 15 knots) and dust source (or hotspots). MSG satellite helps allot to do much better hot spot climatology, and for that, product called Dust Microphisics RGB is widely used. It is derived from three MSG spectral channels. Red color corresponds to difference of channels IR12.0 and IR10.8, green color to the difference of channels IR10.8 and IR8.7 and blue color to the sole IR10.8 channel. In addition to this product Natural Color RGB is also used, but mostly for detection of dust outbreak over the ocean.

In this lecture Jochen Kerkmann, from EUMETSAT, will try to describe dust source regions and dust climatology, how to detect better dust on satellite images, how to discriminate levels of dust and what are the global impacts of dust outbreaks. Also he will mention topics like synoptic patterns and diurnal cycles of dust outbrakes, cloud-dust interaction, forecasting of dust movement and will give a list of typical mesoscale phenomena that can cause dust outbreaks.

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Lecture 12: Forest Fires


Presented by Nuno Moreira (IM)

Forest fires, as a natural phenomena (e.g. ignited due to lightning), is important factor in natural living process of a fores. Nevertheless, problems occur because most of the forest fires are caused by a human action, thus are very difficult to predict in any form. Therefore this lecture is mainly based on detection of forest fire hot spots by satellite means, which is more important in regions with small population covered areas.

Emphasis here is on the infra red 3.9 µm SEVIRI channel, which can be called window channel, but on the other hand it is close to a CO2 absorption band. The importance of this channel we can see through a Wien's law; 3.9 µm is peek wavelength of blackbody with temperature of around 750 K, which is very close to temperature of a fire flame during active phase of fire. Besides forest fire detection, in this lecture you can hear something about detection of aerosols coming from forest fires, identification of burnt areas and about Fire Risk products.

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Lecture 13: Land Applications


Presented by Carla Barroso (IM)

The new generations of sensors on board meteorological satellites (SEVIRI -MSG, ASCAT -EPS, etc. ) enabled a whole new range of products related to the properties of the surface. Applications of such products are great. Some of them are; Vegetation monitoring, Wild Fires detection, Floods and Heat waves monitoring, detection of Urban heat islands, Crop water requirements, etc.

Lecture starts with explanation of Vegetation monitoring and some applications of Vegetation products, such as NDVI index, FVC index, LAI and FAPAR indices. After that Evapotranspiration parameter and Reference evapotranspiration overview is given. And at the end Land surface temperature is observed and various applications of this product are discussed.

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Lecture 14: OSI SAF SST Products and Services


Presented by Pierre Le Borgne (MF)

This short presentation on OSI SAF radiative fluxes Products and Services is given by Pierre Le Borgne from Meteo-France. Two main products that are described here are Surface Solar Irradiance (SSI) product and Downward Longwave Irradiance (DLI) product. For SSI product, physical parametrization is applied and for DLI product bulk parametrization. What is derived from satellite is the visible channel for SSI and cloud precipitation DLI. Hourly SSI and DLI products and the flux validation results are also shown in this lecture.

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Lecture 15: Sea Ice Applications


Presented by Thomas Lavergne (met.no)

Thomas Lavergne from Norwegian Meteorological Institute is presenting the work that has been done within OSI SAF on Sea Ice Applications. General physical role of the sea ice in Earth's system we can look through the radiation. In winter time sea is relatively warmer than atmosphere and when sea ice is present it acts like cover to the sea radiation. On the breaking points of ice thus there is suddenly transfer of moisture and heat from the sea to atmosphere, both sensible heat and radiation. This process is responsible for cloud formation and the weather conditions overall. So for (e.g. ship) safety, weather prediction, climate monitoring or ecosystem studies the information on sea ice coverage is crucial.

To track and measure sea ice motion and concentration, Passive microwave imagers are used (SSM/I or AMSR-E). These instruments are measuring emitted radiances from below. Thus they don't need solar light and can operate both day and night.

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Lecture 16: OSI SAF wind products and services


Presented by Anton Verhoef (KNMI)

Another presenter from the OSI SAF, Anton Verhoef (KNMI), did a lecture on Wind products which are closely related to the concept of scatterometry. Scatterometer is a main instrument that is gathering information on ocean winds. It is a radar instrument mounted on a sattelite. In this lecture the explanation of principle of scatterometry is given along with explanation of deriving wind fields from scatterometer data. Also there is brief overview of currently available wind products and of tools and methods which are available for visualisation and monitoring of the information. At the end of presentation some words will be given about Quality information and Data formats.

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