The relationship between storms and extreme ocean waves in the North Sea is assessed using a long-period wave data set and storms identified in the Interim ECMWF Re-Analysis (ERA-Interim). An ensemble sensitivity analysis is used to provide information on the spatial and temporal forcing from mean sea-level pressure and surface wind associated with extreme ocean wave height responses. Extreme o...

The concept of the ‘‘Asian monsoon’’ masks the existence of two separate summer rainfall régimes: convective storms over India, Bangladesh, and Nepal (the South Asian monsoon) and frontal rainfall over China, Japan, and the Korean Peninsula (the East Asian monsoon). In addition, the Himalayas and other orography, including the Arakan Mountains, Ghats, and Yunnan Plateau, create smaller precipit...

This paper discusses results of a simulation with the regional climate model HIRHAM for 1958-2001, driven by the ECMWF reanalysis (ERA40) data over the Arctic domain. The aim is to analyze the ability of the model to capture certain features of climate extremes derived from daily mean, maximum and minimum temperatures. For this purpose, a range of climate indices (frost days, cold and warm spel...

In this paper extensions to an existing tracking algorithm are described. These extensions implement adaptive tracking constraints in the form of regional upper-bound displacements and an adaptive track smoothness constraint. Together, these constraints make the tracking algorithm more flexible than the original algorithm (which used fixed tracking parameters) and provide greater confidence in ...

ECMWF plans to start assimilating GPS radio occultation measurements with a two dimensional (2D) bending angle operator in 2014. We will describe the new operator, and explain how it has been implemented on the parallel computing system. Issues relating to the computational cost of the operator will be discussed, and a new hybrid approach using a 2D operator in the 4D-Var outer-loop and a 1D op...

Comparison of GOME tropospheric NO2 columns with NO2 profiles deduced from ground-based in situ measurements D. Schaub, K. F. Boersma, J. W. Kaiser, A. K. Weiss, D. Folini, H. J. Eskes, and B. Buchmann Swiss Federal Institute for Materials Science and Technology (Empa), Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland Royal Netherlands Meteorological Institute (KNMI), P.O. Box 201, 3730 AE...