The COST Action 40 "European Sea Level Observing System" (EOSS) has successfully initiated the establishment of the European Sea Level Service (ESEAS). The ESEAS brings together a major fraction of the previously scattered sea level observing and research resources in Europe into a coordinated research organisation.
EOSS officially has been acknowledged by the COST Programme and the EU as one of the successful Actions of recent years, primarily due to the establishment of the ESEAS. The work described here has the goal to support the research infrastructure of the ESEAS through improving the infrastructure for scientifically relevant observations and through further integration of research activities into the frame of the ESEAS.
The primary scientific objective of the ESEAS-RI project is to study sea level variations at inter-annual to century time scales as well as to assess potential future changes in mean sea level. The study will be based on combined sea level observations from tide gauges (which give long time scales up to two centuries) and satellite altimetry (which give increased spatial resolution over a shorter period).
In order to reach the objective, the following main steps are necessary, which in themselves constitute secondary objectives of the project:
Access to the large sea level database in Europe will be possible through the ESEAS. The ESEAS is based on commitments of a total of 27 member organisations, authorities and research institutes from 18 countries. Theses organisations have committed considerable resources to sea level monitoring, climate research and the building of ESEAS. ESEAS has made the initial step in bringing together the formerly scattered sea level research resource in Europe. The ESEAS-RI project will support the building of the ESEAS research infrastructure and, in particular help
In Europe, the physical network for observing sea level at coastal sites is well developed in most geographical regions. More than 170 tide gauges are committed as ESEAS Observing Sites. However, in some parts (particularly the Eastern Baltic Sea, the Adriatic, and parts of the Mediterranean), the ESEAS network needs upgrading of the gauges to modern standards. The ESEAS-RI project will support this uppgrading process.
Tide gauges measure sea level relative to land. For most applications, tide gauges need to be monitored for vertical motion, relative to the adjacent land, as such vertical motion introduces a bias in any derived relative sea level trends. The appropriate methodology for using GPS and absolute gravity at tide gauges in order to connect the tide gauge to the adjacent land, and monitor vertical crustal motion has been developed in the frame of COST Action 40 and implementation of the physical network is in progress in the frame of ESEAS. The ESEAS-RI project will support the augmentation of ESEAS tide gauges with GPS particularly in the Eastern Baltic, the Eastern Mediterranean and the Adriatic.
The processing and analysis methods for GPS at tide gauges providing the better than 1 mm/yr accuracy required for most scientific applications are still in a research state. The ESEAS-RI project aims to develop and validate the observation, processing and analysis strategy required to meet this specification.
Currently, access to the large number of individual sea-level databases in European countries is still severely hampered due to national diversity in operation, uneven technological developments, a multitude of databases, non-standardised products, and different levels of quality assurance. ESEAS is in the process of compiling a major part of the European sea-level related observing activities into one integrated virtual sea-level information source. Eventually, this source will provide a standardised access to most of the sea-level data and information available in Europe, through both national sea-level databases and quality-assured high-level products derived from the ESEAS tide gauges, GPS and satellite altimetry. ESEAS also aims to enhance the value of these databases by setting up standard routines for operational quality control and to ease the exploitation by providing a set of operational products derived from the observations, which meet the requirements of a broad range of scientific and non-scientific users. These developments are co-ordinated also with MedGLOSS network for standardisation of data access and data quality. The ESEAS-RI project will support this process, which is a prerequisite for the scientific exploitation of the sea level observations.
Sea level is an environmental variable important for studying climate processes in the coupled atmosphere-ocean system. ESEAS comprises the research infrastructure for a full exploitation of existing and future sea-level observations. The ESEAS-RI project will derive new regionally consistent data sets of parameters related to sea level. In particular, this will include empirical models of decadal to inter-decadal sea level variations, relative sea level trends, variability of extreme sea levels, vertical crustal movement at coastal sites, and absolute gravity changes. The resulting multi-purpose data sets will be used in the frame of the project as well as being available for other researchers through the ESEAS.
On the basis of these sets of models and parameters, the causes for decadal to inter-decadal sea-level variations could be identified and quantitatively described. Potentially, an empirical relation between sea level variations at the European coasts and phenomena such as the North Atlantic Oscillation (NAO) or the Northern Hemisphere Annular Mode (NAM) could be established.
Storm surges are a major threat for a large portion of the European coasts and low-lying areas. Sea level records provide the basis for assessing the risk of strom surges, which in turn is a prerequisite for planning necessary actions for mitigation. ESEAS brings together the research infrastructure required for a detailed investigation of the statistics of extremes and a risk assessment on a European level on the basis of the data sets made available through the ESEAS-RI project.
Sea level is an important control parameter for coastal dynamical processes. The ESEAS-RI project will provide the data base for research on a European level of sea level trends and variability as input for coastal management and research in coastal dynamics processes.
In summary, the ESEAS-RI project will support ESEAS as a major research infrastructure for all aspects related to sea-level, be it in the field of climate change research, natural hazards and marine research. In particular, the project will improve the utilities for future exploitation of the full research potential in the sea-level observation and research groups through Europe-wide integration.