Statistics for Spatial Data.

Wind speed and wind energy forecast through Kalman filtering of Numerical Weather Prediction model output

The change in the zonal mean atmospheric circulation under global warming is studied in comparison with the response to El Nino forcing, by examining the model simulations conducted for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. In contrast to the strengthening and contraction of the Hadley cell and the equatorward shift of the tropospheric zonal jets in response to El Nino, the Hadley cell weakens and expands poleward, and the jets move poleward in a warmed climate, despite the projected “El Nino–like” enhanced warming over the equatorial central and eastern Pacific. The hydrological impacts of global warming also exhibit distinct patterns over the subtropics and midlatitudes in comparison to the El Nino. Two feasible mechanisms are proposed for the zonal mean circulation response to global warming: 1) The increase in static stability of the subtropical and midlatitude troposphere, a robust result of the quasi-moist adiabatic adjustment to the surface warming, may stabilize the baroclinic eddy growth on the equatorward side of the storm tracks and push the eddy activity and the associated eddy-driven wind and subsidence poleward, leading to the poleward expansion of the Hadley cell and the shift of midlatitude jets; 2) the strengthening of the midlatitude wind at the upper troposphere and lower stratosphere, arguably a consequence of increases in the meridional temperature gradient near the tropopause level due to the tropospheric warming and tropopause slope, may increase the eastward propagation of the eddies emanating from the midlatitudes, and thus the subtropical region of wave breaking displaces poleward together with the eddy-driven circulation. Both mechanisms are somewhat, if not completely, distinct from those in response to the El Nino condition.

Response of the zonal mean atmospheric circulation to El Nino versus global warming

¶The nonhydrostatic Meso model developed at NCEP (Janjic et al, 2001) is based on a new approach. Namely, a hydrostatic NWP model using mass based vertical coordinate has been extended to include the nonhydrostatic motions. In this way favorable features of the hydrostatic formulation have been preserved. This procedure did not require any linearization or approximation. The nonhydrostatic dynamics has been introduced through an add-on module. The nonhydrostatic module can be turned on and off, so that easy comparison can be made of hydrostatic and nonhydrostatic solutions. Here, the basic philosophy behind the discretization methods applied in the model, and not covered by Janjic et al (2001), is discussed, and the latest developments are reviewed. The forecast examples shown indicate that significant differences between hydrostatic and nonhydrostatic forecasts may develop even at relatively coarse resolution of 8 km. Possible future developments are considered.

A Nonhydrostatic Model Based On A New Approach

A nonhydrostatic model based on a new approach

The intense precipitation event that occurred between 3 and 6 November 1994 and caused extensive flooding over Piedmont in northwestern Italy is simulated and tested with respect to various physical aspects, using a meteorological mesoscale model (BOLAM). The period when the most intense rain occurred, mainly covering the second half of 4 and all of 5 November, is examined. A control experiment, starting at 1200 UTC 4 November, simulates the two observed precipitation peaks and captures the magnitude and timing of the most intense precipitation well even at relatively low horizontal resolution (about 30 km). The European Centre for Medium-Range Weather Forecasts analyses are used to provide the initial and boundary conditions. Model output diagnostics and comparison with observations indicate that most of the precipitation is associated with a prefrontal low-level jet, ahead of the cold front, impinging upon the orography of the region (Alps and Apennines). The model simulates a multiple rainband...

Numerical Simulations of the 1994 Piedmont Flood: Role of Orography and Moist Processes

A previsional system for the forecast of the state of the Mediterranean Sea and of surges in the northern Adriatic Sea has been designed and tested. The system consists of a limited area model (the Bologna Limited Area Model, BOLAM), which computes high-resolution pressure and surface wind fields, to serve as the input of a wave model (WAM) and of a shallow water model (two-dimensional Princeton Ocean Model, POM-2D). Results of two case studies are presented, chosen to test the ability of the system to predict extreme surge events originating from cyclonic circulation over the Mediterranean basin. The two case studies cover the periods 4–9 October 1998 and 11–22 November 1996. Comparison with observed buoy data shows that the results of the WAM simulations forced by the wind fields obtained from the high-resolution BOLAM model are significantly better than those obtained using a lower-resolution forcing from the ECMWF analyses. Two domains corresponding to the entire Mediterranean basin and to th...

An Integrated Forecast System over the Mediterranean Basin: Extreme Surge Prediction in the Northern Adriatic Sea

In this paper, the sensitivities of the equitable threat score (ETS) and the true skill score (TSS), obtained with a 2 3 2 contingency table, to continuous precipitation forecast errors are investigated. Two idealized error models are adopted to describe the difference between forecasts and perfect observations. The observations consist of a time series generated by a multiplicative cascade model. The forecasts are constructed by adding the modeled errors to the observations. Two examples that are representative of two precipitation regimes are considered. Monte Carlo simulations of the modeled errors are performed to compute the score uncertainties. Monotonic relationships between the precipitation forecast errors and the two skill scores are found. It is shown that the precipitation regime and the event frequency influence these relationships and the score uncertainties. The score uncertainties also depend on the forecast errors. Furthermore, it is shown that a relationship exists between the ETS and TSS when the forecast errors are very large. Results suggest that more information should be provided together with the scores and their uncertainties in order to provide a complete picture of the forecast performance.

https://journals.ametsoc.org/doi/pdf/10.1175/2009WAF2222211.1

Relationship between Precipitation Forecast Errors and Skill Scores of Dichotomous Forecasts

A. Speranza(), C. Accadia(), M. Casaioli(), S. Mariani() G. Monacelli(), R. Inghilesi(), N. Tartaglione(), P. M. Ruti() A. Carillo(), A. Bargagli(), G. Pisacane(), F. Valentinotti() and A. Lavagnini() () Dipartimento di Matematica e Informatica, Universita di Camerino Camerino, Italy () Agenzia per la Protezione dell’Ambiente e per i Servizi Tecnici Rome, Italy () Dipartimento di Fisica, Universita di Camerino Camerino, Italy () Ente per le Nuove tecnologie, l’Energia e l’Ambiente Rome, Italy () Quadrics Ltd., Rome, Italy () CNR, Istituto di Scienze dell’Atmosfera e del Clima Rome, Italy

POSEIDON: An integrated system for analysis and forecast of hydrological, meteorological and surface marine fields in the Mediterranean area

. Verification of modeled rainfall with precipitation observed by a rain gauge network has been performed in a case study over the Cyprus Island. Cyprus has a relatively dense rain gauge network. The applied verification method is the Contiguous Rain Area (CRA) analysis. Some drawbacks of the CRA method are pointed out when it is applied to such a case study. Impact on the CRA results, when considering different dimensions of the verification sub-domain and different types of indicators (correlation and mean square error) used in the comparison, are discussed. Results indicate that care should be taken when verification of modeled rainfall is performed over a domain smaller than the model one.

/pdf/comparison-of-rain-gauge-observations-with-modeled-2636u62zv1.pdf

N. Tartaglione

Papers

Numerical Simulations of the 1994 Piedmont Flood: Role of Orography and Moist Processes

An Integrated Forecast System over the Mediterranean Basin: Extreme Surge Prediction in the Northern Adriatic Sea

Relationship between Precipitation Forecast Errors and Skill Scores of Dichotomous Forecasts

POSEIDON: An integrated system for analysis and forecast of hydrological, meteorological and surface marine fields in the Mediterranean area

Comparison of rain gauge observations with modeled precipitation over Cyprus using Contiguous Rain Area analysis