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Explore the use of coastal ocean models for monitoring, operational analysis, and forecasting coastal impacts. Learn about the philosophy and hierarchy of models, their applications, validation, and modeling characteristics. Discover how models are applied for different purposes in coastal seas and lands, addressing various needs of the coastal impacts community.
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Coastal ocean model applications that serve the needs of the coastal impacts community Hans von StorchInstitute for Coastal ResearchGKSS, Germany CLIVAR Working Group for Ocean Model Development (WGOMD): Evaluating the ocean component of IPCC-class models Geophysical Fluid Dynamics Laboratory, Princeton, 17 June 2004
Overview • A bit on model philosophy • Our applications of coastal ocean models for operational monitoring purposesand as part of a regional Earth system model.
Models can be very different objects • Maximum simplicity “conceptual” models serve to describe (or embody) “understanding”. They do not allow detailed forecasts of future states and unknown sensitivities. • Maximum complexity “quasi-realistic” models serve to describe the real world as complete and complex as feasible (given the technical resources). They do no provide immediate understanding, but allow for forecasting. • Hierarchy of models, relating conceptual and quasi-realistic models.
Hesse’s concept of models Reality and a model have attributes, some of which are consistent and others are contradicting. Other attributes are unknown whether reality and model share them. The consistent attributes are positive analogs. The contradicting attributes are negative analogs. The “unknown” attributes are neutral analogs. Validating the model means to determine the positive and negative analogs. Applying the model means to assume that specific neutral analogs are actually positive ones. The constructive part of a model is in its neutral analogs. Hesse, M.B., 1970: Models and analogies in science. University of Notre Dame Press, Notre Dame 184 pp.
Positive analog Neutral analog Application
Models are an incomplete replica of the real world • They are consistent with some parts of the observational evidence. • They disregard a greater part of the phase space. • Models can not be verified. • All models are eventually falsified.
To speak about “models of XX” is not useful. • Better language is to refer to “models for the purpose YY”. • YY could be, for instance: • “understanding dynamics ZZ” • “analysing state ZZ” • “predicting state ZZ” • “laboratory to study sensitivity of ZZ to UU” • Different YYs need different models.
Coast = coastal sea+coastal land • The coastal sea is that part of the sea which is affected by or is affecting the land. • The coastal land is that part of the land which is affected or is affecting the sea.
Coasts • Coasts are a globally distributed objects. • They are formed by the close proximity of sea and land. • As coasts are intensely used, coastal problems are mostly of regional character. • For the global earth system, coasts are mostly relevant as sources and sinks of matter.
Influenceson coasts climate variability and change
Purposes of coastal modeling • Operational analysis and forecasting. • Retrospective analysis for detecting and analyzing past, recent and ongoing trends. • Forecasts/scenarios of effects of global change as well as of regional and local usage of catchment and coastal zone. • Understanding dynamics in coastal seas. = YY
Example: Operational needs Currents, waves and wind in the entry area of harbours
WaMoS II VTS Gijón WERA VHS radar Heinz Günther, Coordinator of EUROROSE
Institut für Küstenforschung I f K User interface: current speed and direction
Example: Retrospective analysis Wind, waves, currents, deposition of matter and risks in the North Sea and adjacent coasts
The Helgoland case of wave conditions in Oct 1998 Buoy at 54º9’ N, 7º52’ E, depth 22m (data available 1.10.1998 – 20.10 1998, every 3 hours) Radar (WAMOS) 54º10’N, 7º53’E, depth 7m (data available 9.10.1998-31.10.1998)
Long term regional weather reconstruction • Use of model SN-REMO (REMO + spectral nudging of wind above 850 hPa) Forcing with NCEP re-analyses 1958-2002 • Gridding: 50 km • Time step stored: 1 hourly • Area: Europe • Data freely available
Applications • Assessment of changing storminess • Storm surges • Ocean wave conditions • Long-range pollution – examples: gasoline lead and benz-a-pyren • Commercial applications – Wind energy planning and shipbuilding
Model output vs radar and buoy measurements Significant wave height Lidia Gaslikova, pers. comm. Wave mean direction (coming from)
“Commercial” Applications • Assessment of oil drifts in case of coastal accidents • Assessment of fatigue in ships and off-shore constructions (with FGS Flensburg) • Planning of harbor constructions (Jade Port) • Planning of off-shore wind energy (commercial) • Assessment of coastal defense measures (ALR) • Wave conditions in the Elbe estuary. source Ulrich Callies, GKSS
Example: Scenarios Wind, waves, currents, water levels and risks in the North Sea and adjacent coasts
Scenarios of North Sea storm surges • Wind from downscaled global scenario is used to determine expected change in wind force, storm surges, ocean waves and erosion. • Representative for 2070-2100;not strongly dependent on used regional atmospheric model. • For the North Sea storm surges, a significant increase of a few decimeters is found along the southern and eastern coast line. • Effect of oceanic volume change (warming; melt water: 10-90 cm) has to be added. • New defense measures need to be considered. Climate change runControl run Estimated annual maximum storm surge heights along the North Sea coast (scenario A2; Woth)
Projections for the future / surge meteorological forcing: HIRHAM / RCA Differencesin inter-annual percentiles of surge/ A2 - CTL: RCA Differences in inter-annual percentiles of surge/ A2 - CTL: HIRHAM Katja Woth, unpublished, PRUDENCE project, 2003
Outlook Coastal sea ocean models should be expanded: • Introduction of more constituents – chemicals, biotic material, suspended matter, sand … • Coupling with wind waves, bathymetry (morphodynamics), ecology, chemistry • Explicit representation of tides; time variable domain (Wadden areas); flexible nesting. • Much higher resolution of both atmospheric forcing as well as oceanic description, allowing for decadal simulations. Coastal modeling needs: • Availability of high-resolution coastal sea operational analyses and decadal re-analyses.