Cyclone Xaver seen by geodetic observations

Abstract

Abstract Cyclone Xaver pounded the North Sea on 5–6 December 2013 and reached its maximum in the German Bight the second day. Combined geodetic measurements from the SARAL/AltiKa satellite and from a local geodetic network detect cross‐shelf and alongshore variations and loading vertical deformation. The cross‐shelf root‐mean‐square differences between observations and predictions are 30 cm for surge height, 2 m for significant wave height, and 4 m/s for wind speed, with significant biases. The different wind forcing mainly causes the predicted height differences. The smallest standard deviation difference between observed and predicted vertical displacements is from HyFlux2 forced by DWD wind, with a 52% reduction in the standard deviation by subtracting prediction from observations. The GPS network monitors the anticlockwise surge path with maximum land subsidence of 3–5 cm. The tide gauge network monitors both the anticlockwise path of the external wave and the surge associated with strong northwesterly winds.