Identify and interpret fields and derived products
Luca Ciabatta presents an algorithm that retrieves precipitation amounts from soil moisture measurements.
Length: 19 minutes
SM2RAIN is a novel algorithm that allows to estimate rainfall from a different perspective, using the soil as a natural rain gauge. The algorithm has already been applied to several satellite soil moisture products both on a regional and global scale, providing high-quality rainfall data. Moreover, soil moisture-derived rainfall estimates have been found to be complementary to state-of-the-art top-down precipitation products. In this way, the integration of the two different approaches provides a more reliable rainfall product. Within H SAF, the SM2RAIN algorithm has been applied to Surface Soil Moisture (SSM) data obtained through Metop platforms. The SSM-derived rainfall data are then integrated with the Level 3 PMW H67 product. In this way, the integrated product P-AC-SM2RAIN (labeled as H64) can provide daily rainfall estimates with a spatial resolution of 0.25°, over the extended H SAF area (LAT 60°S – 75°N, LON 60°W – 60°E).
Silvia Puca presents how H-SAF products can help in an early warning system.
Length: 22 minutes
Many severe meteorological events occurred in Europe during the last decade and caused casualties and damages to the historical heritage and natural environment. The European Civil Protection agencies, supported by meteorological and hydrological institutes, aim to assess risk scenarios, to monitor and supervise events and risk levels, providing early warning to National and local authorities. Near real time accurate estimations of hydrological variables such as precipitation and soil moisture are invaluable for the hydrological risk evaluation, enable them to issue early warnings and plan for disaster relief at the local level. Besides measurements of key hydrological variables by ground-based instruments, often affected by a limited spatial coverage, advanced satellite-based precipitation and soil moisture products developed within different international programs as H SAF, are available and accessible to users in near-real time. Severe meteorological events are selected in order to understand how the main satellite precipitation product characteristics, i.e. accuracy, spatial pattern and resolution, update frequency and latency, impact the efficiency of a hydro-meteorological early warning system at a local level in an operational framework.
Jan Kanak talks about comparing H-SAF products against ground truth data and shows some examples over Europe.
Length: 32 minutes
For proper usage of satellite products in meteorological applications it is necessary to take the set of skills which can be divided into technical, logistic and routine work with data, and final application of meteorological knowledge base by means of interpretation tools. Our lesson will provide step by step introduction to validation work with the H SAF precipitation products, introducing BUFR, GRIB and NETCFD decoding, reading and upscaling with the aim to put these various satellite products into common grid suitable for comparison against essential precipitation measurements considered as ground truth. Passing through the validation process and being aware of the accuracy of satellite products, we will show the applicability of these data using selected show cases over Central Europe. Case studies were prepared to demonstrate possibilities but also shortcomings of satellite data, which users need to take into account in practical usage. Because the proper preparation of satellite products is not important only for validation process itself, but also for practical applications, using show cases we will explain how to merge together various sources of precipitation information, e.g. irregular rain gauge point data, regular radar grid data, satellite scanned grids derived from microwave and infrared imagers. We will discuss the special treatment of continuous and discreet parameters like precipitation intensity or accumulated rain versus precipitation phase, quality index and surface type’s parameters to be up-scaled into common grid. Once up scaled data can be merged with the aim to obtain the most probable final values of instantaneous and accumulated precipitation fields. Final message of this training lesson addressed to meteorologists and hydrologists will be targeted to understanding that precipitation must be considered as stochastic parameter describing complex 3D processes in the atmosphere.
Leo Pio D'Adderio talks about the so-called Mediterranean hurricanes (Medicanes) or tropical-like cyclones (TLCs) as well as the severe precipitation events associated to atmospheric rivers.
Length: 34 minutes
The Mediterranean Sea is recognized as a climatic hotspot, often affected by severe weather events that are becoming more and more frequent in the last decades. Extreme events originating over the Mediterranean Sea and hitting the coast can have tremendous impact both from hydrological point of view as well as in terms of human and economic losses. Among these events, increasing attention has been recently devoted to the so-called Mediterranean hurricanes (Medicanes) or tropical-like cyclones (TLCs) as well as to the severe precipitation events associated to atmospheric rivers. This presentation shows the potentials of H SAF products together with measurements collected by active and passive microwave sensors onboard LEO satellites for the characterization and monitoring of the precipitation associated to severe weather events during their different evolution phases.
Marco Petracca talks about the validation of H-SAF precipitation products.
Length: 31 minutes
The H SAF Precipitation Product Validation Group (PPVG) annually analyses all the operational precipitation products released by the consortium in order to check the quality and evaluate their performance over time. The Quality Assessment (Q.A.) service is carried out by comparison with precipitation data used as reference. The comparison over the Europe is performed with radar and rain gauge data belonging to eight European countries: Belgium, Bulgaria, Germany, Italy, Hungary, Poland, Slovakia and Turkey. The methodology used to evaluate the quality of precipitation products is common to all member states through the use of a same algorithm (named Unique Common Code). Over African areas the comparison is performed with respect to the Dual-frequency Precipitation Radar (DPR) products of the Global Precipitation Measurement (GPM). Data used, methodology applied, and results obtained will be presented.
Davide Melfi presents a method that blends GEO and LEO precipitation products.
Length: 19 minutes
The main precipitation products developed worldwide are based on microwave (MW) radiometry Microwave (MW) radiation is the most effective for precipitation retrieval because of the direct interaction of radiation with the frozen and liquid hydrometeors within precipitating clouds as opposed to visible or infrared observations sensitive to the upper portion of the clouds. However, as microwave instruments are currently only available on-board satellites in Low Earth Orbit (LEO), they do not provide a continuous monitoring of rainfall over a given location. One methodology is to combine geostationary and low orbit satellite observations. This kind of multi-platform algorithm provides global precipitation estimation merging high quality, sparsely sampled data from low earth orbit satellites (e.g. Metop, NOAA series, DMSP, i.e. LEO/MS in general) with continuously sampled data from geostationary satellites (e.g. GEO/IR). The presentation will describe an example of such retrieval techniques used in HSAF and the future approach in combining such different sources of data.
Simone Gabellani presents a merging approach of rain gauge data with remote precipitation retrieval to improve flood modelling.
Length: 68 minutes
Multi-sensor data fusion prove that combining data from rain gauges and remote retrievals represents the best way to obtain an enhanced and more reliable evaluation of Quantitative Precipitation Estimation (QPE) that improve hydrological modelling for river discharge estimation. Although remote sensors produce an observation of precipitation subject to several sources of uncertainty, they capture the general covariance structure of the precipitation field. Thus, the information provided by remote sensors may be used to condition the information from rain gauges, which is limited in terms of spatial representativeness. In this way, an estimate of the rainfall field containing a more realistic spatial structure constrained to the rain gauges data can be produced. The presentation will describe the theoretical background and examples for merging satellite and gauge rainfall data for improving discharge modelling. A Modified Conditional Merging (MCM) approach, developed from the original Conditional Merging proposed by Sinclair and Pegram (2005), will be illustrated.
Giulia Panegrossi presents the challenges and recent advancements in satellite-based snowfall quantification and global monitoring.
Length: 37 minutes
Snow plays an important role in the Earth energy exchange processes, and is a fundamental element of the water cycle. The use of satellites for snowfall monitoring and quantification and for retrieving snow cover properties and variability is necessary to globally quantify water resources. Satellite-based snowfall detection and surface snowfall rate estimation are becoming an increasingly popular topic within both the hydrological scientific community and operational services. Recent studies have evidenced how space borne multi-channel microwave (MW) radiometer measurements respond to both snowfall and snow cover properties. In this presentation the challenges and recent advancements in satellite-based snowfall quantification and global monitoring will be discussed, and the retrieval strategies that are being adopted within the EUMETSAT H SAF to improve detection and quantification of snowfall, with particular focus on higher latitudes, will be presented.
Kari Luojus shows the basic approach to apply passive microwave radiometer data for retrieval of terrestrial snow water equivalent.
The presentation shows the basic approach to apply passive microwave radiometer data for retrieval of terrestrial snow water equivalent. It describes the GlobSnowmethodology to combine satellite-based radiometer data with ground-based snow depth observations and a bias-correction approach to improve the satellite-based retrievals. It also presents the historical satellite-based reconstruction of Northern Hemisphere snow mass, from 1980 to present day (published on Nature, Pulliainen et al. 2020). Pulliainen, J., Luojus, K., Derksen, C. et al. Patterns and trends of Northern Hemisphe re snow mass from 1980 to 2018. Nature 581, 294–298 (2020). https://doi.org/10.1038/s41586-020-2258-0
Niilo Siljamo investigates the quality of H-SAF snow products.
H-SAF satellite snow extent products can be used for many meteorological and hydrological applications, for example as inputs for weather models. What are these products? How good are they? Especially, MSG/SEVIRI (H31) and Metop/AVHRR (H32) products are described with examples and validation results.
Steinar Eastwood presents the OSI-SAF products and shows climatological applications of the data.
The sea ice products from the EUMETSAT Ocean and Sea Ice Satellite Application Facility are widely used. In this presentation the sea ice products will be presented and examples of use in operational numerical weather and ocean modelling will be given.
Mária Putsay discusses how single channels and RGB types can be effectively used for snow detection.
Single channels and RGB types will be discussed and compared from the snow detection point of view: how effectively they can be used for this purpose, which benefits and limitations they have. Physical background will be discussed and several examples will be shown.
Ideally an RGB type is usable for snow detection if the snow-covered cloud-free surface has good colour contrast against both now-free surface and clouds. Practically, one problem may cause difficulty: ice clouds and snowy land often appear similarly. Not surprising: their physical properties are similar as both consist of ice crystals. The presentation discusses which RGB types show snow and ice clouds less similarly. Forecasters usually look at animations, this also helps to distinguish snow covered area from moving ice clouds.