Atmospheric dynamics in the tropical regions is dominated by unbalanced motions in response to convective processes, found to vary on many temporal scales from diurnal to inter-seasonal and inter-annual scales. The gravest wave excited by convection is the Kelvin wave and it is characteristics by eastward and upward propagation away from its convective source. As it propagates vertically, a pac...

The performance of the European Centre for Medium-Range Weather Forecasts (ECMWF) model in simulating clouds is evaluated using observations by the Geoscience Laser Altimeter System lidar on the Ice, Cloud, and Land Elevation Satellite (ICESat). To account for lidar attenuation in the comparison, model variables are used to simulate the attenuated backscatter using a lidar forward model. This g...

Numerical weather prediction models as well as the atmosphere itself can be viewed as nonlinear dynamical systems in which the evolution depends sensitively on the initial conditions. The fact that estimates of the current state are inaccurate and that numerical models have inadequacies, leads to forecast errors that grow with increasing forecast lead time. The growth of errors depends on the f...

An important part of the scatterometer wind data processing is the quality control (QC). This report shows the implementation of a new scatterometer QC procedure, based on a comprehensive analysis of the wind inversion residual, which significantly improves the effectiveness of the wind data QC. The method is applied on the Advanced Scatterometer (ASCAT) onboard Metop-A, but is generic and can ...

We present an efficient particle filtering algorithm for multiscale systems, which is adapted for simple atmospheric dynamics models that are inherently chaotic. Particle filters represent the posterior conditional distribution of the state variables by a collection of particles, which evolves and adapts recursively as new information becomes available. The difference between the estimated stat...

The SATREP (Satellite Report) is a detailed description of the IR and WV image in terms of conceptual models, making use of ECMWF model fields and of surface weather reports. It is meanwhile produced four times a day, at ZAMG during the day (06 and 12 UTC), at FMI in the evening (18 UTC) and at KNMI in the nightshift (00 UTC). It is desirable to have the SATREP in higher temporal frequency whic...

The performance of the ARPA-SMR Limited-area Ensemble Prediction System (LEPS), generated by nesting a limited-area model on selected members of the ECMWF targeted ensemble, is evaluated for two flood events that occurred during September 1992. The predictability of the events is studied for forecast times ranging from 2 to 4 days. The extent to which floods localised in time and space can be f...

This paper presents a quantitative methodology for evaluating air–sea fluxes related to ENSO from different atmospheric products. A statistical model of the fluxes from each atmospheric product is coupled to an ocean general circulation model (GCM). Four different products are evaluated: reanalyses from the National Centers for Environmental Prediction (NCEP) and the European Centre for Medium-...

A wavelet based methodology has been developed to retrieve the wind field over the sea surface from SAR images without any a-priori information of the wind direction. The method relies on the ability of the twodimensional continuous wavelet technique to detect the spatial structure of the Marine Atmospheric Boundary Layer (MABL). The analysis of the geometric and radiometric characteristics of ...

[1] A new type of radio occultation (RO) data, recorded in open-loop (OL) mode from the SAC-C satellite, has been tested for monitoring refractivity in the Atmospheric Boundary Layer (ABL). Previously available RO signals, recorded in phase-locked loop mode were often unusable for sensing the lower troposphere (LT) or resulted in significant inversion errors, especially in the tropics. The OL R...