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Short-range Forecasts (short-range + forecast)

Distribution by Scientific Domains
Earth and Environmental Science60%

Selected Abstracts

Monitoring the observation impact on the short-range forecast

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 638 2009
Carla Cardinali
Abstract This paper describes the use of forecast sensitivity to observations as a diagnostic tool to monitor the observation impact on the 24-hour forecast range. In particular, the forecast error is provided by the control experiments (using all observations available) of two sets of observing system experiments performed at ECMWF, a month in summer 2006 and a month in winter 2007, respectively. In such a way, the observation data impact obtained with the forecast sensitivity is compared with the observing system experiment's data impact; differences and similarities are highlighted. Globally, the assimilated observations decrease the forecast error; locally, some poor performances are detected that are related either to the data quality or to the suboptimality of the data assimilation system. It is also found that the synoptic situation can affect the measurements or can produce areas of large field variability that the assimilation system cannot model correctly. Copyright © 2009 Royal Meteorological Society [source]

Can ensemble forecasts improve the reliability of flood alerts?

JOURNAL OF FLOOD RISK MANAGEMENT, Issue 4 2009
J. Dietrich
Abstract A probabilistic evaluation of ensemble forecasts can be used to communicate uncertainty to decision makers. We present a flood forecast scheme, which combines forecasts from the European COSMO-LEPS, SRNWP-PEPS and COSMO-DE (lagged average) ensemble prediction systems with a rainfall,runoff model. The methodology was demonstrated with a case study for the Central European Mulde River basin. In this paper, we summarize results from hindcast simulations for seven events from 2002 to 2008. The ensemble spread resulting from uncertainty in rainfall forecast was very high at 2,5 days lead time. The median of the medium- and short-range forecasts and a lagged average ensemble of the very short-range forecasts proved to be reliable regarding the probability of exceeding flood alert levels. However, the limited number of observed events does not allow for the postulation of prescriptive binary decision rules. Flood managers have to adapt their decisions when new information becomes available. [source]

Passive microwave radiometer channel selection basedoncloudandprecipitation information content

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 617 2006
Sabatino Di Michele
Abstract The information content of microwave frequencies between 5 and 200 GHz for rain, snow and cloud water retrievals over ocean and land surfaces was evaluated using optimal estimation theory. The study was based on large datasets representative of summer and winter meteorological conditions over North America, Europe, Central Africa, South America and the Atlantic obtained from short-range forecasts with the operational ECMWF model. The information content of rain, snow and cloud water was traded off against the uncertainties due to the natural variability of other variables that microwave observations are sensitive to. These are surface emissivity, land surface skin temperature, atmospheric temperature and moisture. The estimation of the underlying error statistics was based on ECMWF model forecast error statistics. The results suggest that a number of frequency bands are most suited for the retrieval of (i) rain over oceans: 15,18, 35,40, 80, 145, 118.75±10,14 GHz; rain over land: 85,100, 135,140 GHz, (ii) snow over land and oceans: 95,100, 140,150, 187 GHz, (iii) clouds over oceans: 40, 80,85 GHz; clouds over land: 90,100, 135,140 GHz. For radiometers designed for global and multi-season applications, several channels in all of the above frequency ranges would be desirable for optimizing channel usage in hydrometeor retrievals depending on the observed situation. Copyright © 2006 Royal Meteorological Society. [source]

The relative impact of meteorological observations in the Norwegian regional model as determined using an energy norm-based approach

ATMOSPHERIC SCIENCE LETTERS, Issue 1 2010
Andrea Storto
Abstract The sensitivity of the forecasts to different observation groups is evaluated by comparing moist total energy norm-based cost functions within the HARMONIE/Norway regional model. We quantify the quality loss associated to each observation type. The use of a localisation operator has allowed us to obtain results for the whole domain and for the area of continental Norway only, as well as for different vertical sub-regions of the atmosphere. Results show a prominent role of in situ observations for short-range forecasts, while for medium-range forecasts microwave satellite observations result in the largest impact, especially the AMSU-A channels peaking within the troposphere. Copyright © 2010 Royal Meteorological Society [source]