Guidelines for Metocean Data Analysis

ABSTRACT Metocean studies involve a lot of statistical analyses in the fields ofdata validation, determination of normal and extreme metoceanconditions and data transformation. All these analyses can beperformed in different ways. Deltares’ best practice guidelines toexecute metocean studies in an efficient and standardized way aresummarized. Special attention is paid to the execution of extreme valueanalyses, for which procedures based on the extreme value theory arerecommended. KEY WORDS: metocean conditions; offshore; nearshore; datavalidation; extreme value analysis; sea state analysis; guidelines. INTRODUCTION The design of marine structures, such as offshore structures, windparks, coastal structures, etc, generally starts with a metocean study inwhich the mean, operational and extreme environmental conditions thatthe structures will have to withstand are determined. The detail andextent of the required metocean conditions (waves, water level,temperature, currents and wind) are, however, study dependent. On theother hand, most of the studies involve data validation, determination ofnormal and extreme metocean conditions and offshore to nearshoretransformations of data.Deltares often carries out metocean studies for a varied spectrum ofclients such as project developers, governments, local businesses,contractors, oil and gas producers, etc. The involvement of the clientsin the various technical aspects of the metocean study varies greatlydepending on their in-house expertise. Given that several of thestatistical analyses involved in a metocean study can be performed indifferent ways, of which some are based on ‘pragmatic’ and non-theoretically sound approaches, it was found necessary to createguidelines in which the execution of metocean studies is standardized.These guidelines focus on the following four aspects: (1) datavalidation, (2) normal conditions, (3) extreme conditions, and (4) seastate analysis. In parallel with the guidelines, Deltares has alsodeveloped a MATLAB tool,