Since many aspects of our lives are dominated by the weather, watching the forecast is part of our daily routine. The economic and social benefits of accurate weather forecasts are immense. For example, they help improve the efficiency of agricultural systems, they are used to optimise logistical aspects of transport and energy, and they help ensure our safety. Today's weather forecasts are based on complex numerical models that assimilate a huge number of different geophysical measurements to simulate the behaviour of the atmosphere. The majority of these measurements are provided by satellites. Research into ways of improving the forecasts is constantly in progress, particularly with the intent to early warning of extreme events, the nature and frequency of which may change as a consequence of climate change.

Copernicus satellites provide global information about the composition of the atmosphere and the state of Earth's surface that can support weather forecasts.

The accuracy and reliability of weather predictions relies on the availability of satellite observations. Sea-state parameters such as sea-surface temperature, waves, currents and sea level can help model the exchange processes between the ocean and atmosphere more accurately. Also, atmospheric aerosols, dust and ozone concentrations can improve the understanding of the boundary conditions related to atmospheric forcing. Different kinds of satellite instruments from radar altimeters and temperature radiometers, to atmospheric ultraviolet spectrometers, can be used to provide additional information complementing data from operational weather missions such as EUMETSAT's Meteosat and MetOp.

The European Centre for Medium-Range Weather Forecasts (ECMWF) is a worldwide leading international organisation that develops and operates global models and data-assimilation systems to predict the behaviour of the atmosphere in the medium range and also up to longer periods of time by using probabilistic techniques. Every day, its powerful computing systems assimilate in near real-time over 12 millions of observation data from about 60 different satellites and from various ground networks. This figure is a typical ECMWF chart showing the forecast mean sea level pressure and wind speed for 05 November 2012 – these are key parameters in weather forecasts as they show how the air is moving and where storms are developing.

Source: ECMWF

HOW SENTINELS CAN SUPPORT SPACE-BASED WEATHER PREDICTIONS

LAND MARINE ATMOSPHERE EMERGENCY MANAGEMENT CLIMATE CHANGE SECURITY

ISSUE 26 / SEPTEMBER 2013

Facts

> In Europe, the gross revenue from commercial weather forecasts amounts to €40 million

> Overall, weather forecasts in the EU are estimated to bring financial benefits of €15 to 60 billion/year

> More than 90% of all observational data used in global numerical weather prediction comes from satellites

Benefits

Satellite data support weather forecasts to

> improve day-to-day reliability by providing routine observations all over the globe

> improve the accuracy of numerical models and so the understanding of weather processes

> improve early warning of hazardous weather leading to better protection of life and property

Policy Objectives

> EU Water Framework Directive

> EU Flood Directive

> Clean Air for Europe (CAFE)

www.esa.int/copernicus • http://copernicus.eu/

ESA's new global environmental satellite

The Sentinel-3 mission main objective is to measure sea-surface topography, sea- and land-surface temperature and ocean- and land-surface colour with high-end accuracy and reliability in support of forecasting systems, as well as for global environmental and climate monitoring. The mission will provide systematic data all over the globe. This is beneficial to support weather forecasts especially for areas where ground networks are scarce - notably over the oceans. Oceans play a key role in governing global weather patterns, and their characterization will become even more important in the future when coupled ocean-atmosphere models are expected to bring further improvements in weather predictions.

The first Sentinel-3 satellite will be ready for launch in 2014, followed by a second satellite to provide the required level of coverage for Copernicus services. The Sentinel-3 marine component will be operated by EUMETSAT, as Sentinel-4 and -5.

Sentinel-3

This image shows sea-surface temperature over the Atlantic as measured by Envisat's Advanced Along Track Scanning Radiometer (AATSR). The blue areas are corresponding to coldest waters and red to the warmest. AATSR, a precursor of the SLSTR that will be carried on Sentinel-3, was capable of measuring sea-surface temperature to an accuracy of a few tenths of a degree.

Source: ESA

ISSUE 26 / SEPTEMBER 2013

The Copernicus Services for Atmosphere, Marine and Land Monitoring make use of satellite data to provide continuous data and information on atmospheric composition and the state of Earth’s surface, thereby supporting weather forecasts and reanalysis.

Example products:

> Nowcasting and forecasting of atmospheric and ocean parameters at global and regional scales

> Re-analysis of weather parameters at various temporal resolutions (e.g. dust and ozone)

The Copernicus Sentinel-3, -4 and -5 and -5P missions will support weather forecasting by:

> determining global sea-surface temperatures with the Sea and Land Surface Temperature Radiometer (SLSTR) (Sentinel-3)

> providing accurate topographic measurements with an advanced dual-frequency Synthetic Aperture Radar Altimeter (SRAL) (Sentinel-3)

> monitoring the composition of the atmosphere, including air quality, stratospheric ozone and solar radiation (Sentinel-4, -5 and -5P)

Sentinel contribution

> Establish seamless European monitoring and forecast services for weather, ocean and atmospheric composition at different spatial scales: global, continental, regional, local

> Improve the skills of numerical models using available data from integrated observing systems across all timescales

> Continue to acquire high-quality satellite data for initialisation of predictive models and for ocean–atmosphere and land–atmosphere coupling

> Provide space-based, consistent real-time and re-analysed datasets

COPERNICUS ACTIVITIESCopernicus services Next steps

www.esa.int/copernicus • http://copernicus.eu/