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Tropical cyclones (TCs) are one of the most severe weather hazards in the tropics, causing many human deaths and substantial property loss. Therefore, it is always urgent to significantly reduce systematic errors that may hinder the accurate forecast of TC activity. To evaluate the ability of the Euro-Mediterranean Center for Climate Change (CMCC) forecast system to represent TC activity and to verify the feasibility of TCs forecast, we use a new version of the CMCC Seasonal Prediction System (SPS3.5), which configures with high spatial resolution (0.5 degrees) in the atmospheric component and a large (40) number of ensemble members. We compared SPS3.5 hindcasts from 1998 to 2016 July-September with observed TC tracks derived from the International Best Track Archive for Climate Stewardship (IBTrACS). To identify storms and track their trajectories in SPS3.5, we use the Geophysical Fluid Dynamics Laboratory (GFDL) Tropical Cyclone tracking algorithm and set strict thresholds to ensure the authenticity of the captured TCs. We find that the SPS3.5 system captures the spatial distributions in the North Hemisphere (R~0.8) well, although it underestimates TCs' number magnitude, which relates to the model resolution and thresholds. TCs spatial distribution is best captured over the Pacific, where the largest peak season (August) is covered by our dataset, while lower-skill is shown over the North Atlantic Ocean and the North Indian Ocean. For TC variability, the model performs well only in the Western North Pacific (R up to 0.6). We also investigate the relationship between TCs' intensity and interannual variability with ENSO., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Regimes of the northern extratropical circulation in winter are identified in this paper as clusters of atmospheric states in a low-dimensional phase space generated by the leading EOFs of eddy geopotential fields. Our algorithm seeks points corresponding to local maxima for the density of atmospheric states; subsequently, a cluster is defined around each density maximum as that portion of the phase space in which the observed density can be locally approximated by a unimodal function. Six clusters were found. The largest cluster includes 40% of the field in our sample; but it possesses a positive projection on the Pacific-North American (PNA) pattern. The other five clusters represent anomalous flow regimes and include 52% of the fields. One of them shows a low amplitude of the planetary waves; the remaining four represent states with large wave amplitude but different phases. -from Authors

Given the new parametrization adopted at ECMWF (European Center for Medium Weather Forecasts - Shinfield Park Reading U.K.) with a closure based on a quasi-equilibrium assumption for convective motions, a strategy can be adopted to compare high resolution non-hydrostatic models either with explicit convection or different convective parametrization. In fact the ECMWF forecasts with the NEW convective parametrization are distributing the moist energy to the convective activity with different mechanisms arising from the sensitivity of the moist energy to surface and boundary layer processes that act to differentiate their adjustment time scale. The effect of using different initial surface condition to start and to trigger convection, can be compared in real cases where surface and boundary layer conditions seem to be the main trigger of convective events. One outcome of this is how the equilibrium and non-equilibrium condition could be imposed in numerical weather prediction models (NWP) that have different parametrization and if this can help to forecasts better deep convective events.

The CLOUDS study defines a small satellite addressing the objective of cloud-radiation interaction monitoring for improved climate and weather prediction. The study was funded by the EC, and now various paths are explored to provide study continuation and eventual programme implementation. Only passive radiometers are included, covering the spectral range from UV to MW, with more polarisations and viewing geometries. There are six instruments, four (the optical ones) integrated into a single package, one in MW, one in Sub-mm waves. All instruments have conical scanning, with fore- and aft- views; one has multi-angle capability. The resolution is 5 or 10 or 40 km depending on the instrument, and the observing cycle is 24 h for measurement from TIR or MW, or 48 h for measurements which involve channels operating with solar radiation. Sizing parameters of CLOUDS are: mass ~ 900 kg, power ~ 1.6 kW, data rate 1.1 Mbps for direct read-out in S-band, 30 Mbps for global data in X-band, volume compatible with launch by Eurockot. © 2003 Published by Elsevier Science Ltd.

The influence of horizontal resolution on model systematic error and skill scores are examined for both winter and summer seasons from a set of extended-range integrations of the ECMWF numerical weather prediction model. The forecast data are composed of 24 30-day integrations, two per month from successive 12 GMT operational analyses, from April 1985 to March 1986 at four (triangular truncation) horizontal spectral resolutions of T21, T42, T63 and T106. Systematic errors in wind, temperature, heat and momentum fluxes are discussed, both in the tropics and extratropics. Dynamical reasons for differences between various model resolutions and between simulations and observations are proposed. Diagnosis of model systematic error is aided by comparing zonal-mean diagnostics of the observed flow in the northern hemisphere winter and southern hemisphere winter. The impact of resolution on regional simulations of rainfall during the Indian and African monsoons is also discussed. In the extratropical troposphere, the behaviour of the T21 model is quite distinct from the higher-resolution models. The southern hemisphere flow is weak, and in both hemispheres horizontal momentum fluxes are severely underestimated. The systematic errors of the T42, T63 and T106 models are quite similar to each other in the extratropical troposphere. Errors at these higher resolutions resemble the observed difference (in zonal-mean wind, temperature and eddy fluxes) between diagnostics in the northern hemisphere winter and southern hemisphere winter, suggesting that orographic forcing in this version of the ECMWF model is inadequate, despite the inclusion of envelope orography.