  The joint extremal spatial dependence of wind speed and significant wave
height in the North East Atlantic is quantified using Metop satellite
scatterometer and hindcast observations for the period 2007-2018, and a
multivariate spatial conditional extremes (MSCE) model, ultimately motivated by
the work of Heffernan and Tawn (2004). The analysis involves (a) registering
individual satellite swaths and corresponding hindcast data onto a template
transect (running approximately north-east to south-west, between the British
Isles and Iceland), (b) non-stationary directional-seasonal marginal extreme
value analysis at a set of registration locations on the transect, (c)
transformation from physical to standard Laplace scale using the fitted
marginal model, (d) estimation of the MSCE model on the set of registration
locations, and assessment of quality of model fit. A joint model is estimated
for three spatial quantities: Metop wind speed, hindcast wind speed and
hindcast significant wave height. Results suggest that, when conditioning on
extreme Metop wind speed, extremal spatial dependence for all three quantities
decays over approximately 600-800 km.
