Simulation of heavy precipitation events in Madeira Island using resolution of 1 km Simulation de précipitations orographiques intenses sur Madère (résolution 1km) Flavio T. Couto Évora University, Physics Department, Évora, Portugal. Geophysics Centre of Évora – CGE, Évora, Portugal.

Introduction about the Madeira island Materials and model configuration Results and Conclusions OUTLINE

The Madeira Island is: situated at 32◦45N and 17◦W; a little island with an area of 737 km2 and a maximum altitude of m at Pico Ruivo; completely formed by volcanic materials with an approximately E–W-elongated form (58 km long and 23 km width), able to block and deviate the wind around and above; Introduction Fig.1: Orography of Madeira simulated with the Meso-NH, using the GTOPO30 data base and 1km resolution.

The precipitation in the island is influenced by subtropical anticyclone winds, (summer season), low pressure and frontal systems passage (winter), as well as the persistent covering of fog, which normally exists between the 800–1,600 m altitude. MOTIVATION Evidences of heavy precipitation during the winter 2009/2010, for example, the disaster occurred on 20 February 2010, when the Madeira Island was hit by intense precipitation, causing more than 40 deaths, and a vast range of material losses, including the destruction of houses, roads and bridges. Introduction

GOALS: to analyze the main atmospheric characteristics associated with the events; to expand the understanding of the interaction between the Island and the atmospheric circulation, mainly the effects of the orography in the generation/intensification of precipitation; to evaluate the performance of Meso-NH in simulate heavy precipitation over Madeira with high-resolution.

Materials Simulations of the Meso-NH model; Rain gauge data and synoptic charts obtained from Portuguese Meteorological Institute; Precipitable water from satellite observations;

Areeiro station: 1) 15/12/2009 – 129,2 mm 2) 17/12/2009 – 131,5 mm 3) 22/12/2009 – 127,7 mm 4) 28/12/2009 – 135,1 mm 5) 02/01/2010 – 168,5 mm 6) 02/02/2010 – 273,1 mm 7) 20/02/2010 – 387,1 mm Rain gauge analysis Rain gauge analysis Materials most intense event Day

Atmospheric River

Materials Model configuration: 3 horizontal domains: D1: 40x40 points, 9 km resolution; D2: 60x60 points, 3 km resolution; D3: 90x60 points, 1 km resolution; Vertical grid with 45 levels.

Materials Model configuration: -Diagnostic mode Initial and boundary conditions updated every 6 hours and obtained from the ECMWF analyses; -Prognostic mode Initial and boundary conditions updated every 3 hours and obtained from the ECMWF prognostics;

Materials Model configuration:

Accumulated precipitation (Diagnostic Mode) Accumulated precipitation (Diagnostic Mode) Results and conclusions

Accumulated and hourly precipitation well represented Accumulated and hourly precipitation poor represented Areeiro station - Case 02 Feb Calheta station - Case 02 Feb Caniçal station - Case 02 FebLombo da Terça station - Case 22 Dec

Accumulated precipitation (Prognostic Mode) Accumulated precipitation (Prognostic Mode) Case 20 February 2010 Results and conclusions

Some preliminary conclusions In general, the Meso-NH have been responded satisfactorily to the aims of this study: - Confirming the orographic effect in intensification of the precipitation; - Identifying some aspects of mesoscale related to some mechanisms of orographic precipitation, for example: - Interaction between the mesoscale (e.g. orography) and large scale (e.g. Atmospheric Rivers); Houze (1993)

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