NUMERICAL SIMULATIONS OF MAP IOP2B WITH AROME

The goal of this study is to use the large amount of measurements collected during the MAP IOP2B, to validate a new Numerical Weather Prediction system : AROME. We also evaluate AROME by comparison with ALADIN and Meso-NH simulations of this IOP. The AROME 2.5 km results are sensitive to the choice of the coupling model. AROME 2.5 km coupled with AROME 10 km is able in pseudo-operational conditions (long time step and coupled with forecasts) to reproduce the main features of the IOP2B. In this configuration it produces results closest to the Meso-NH reseach model ones

NUMERICAL SIMULATIONS OF MAP IOP2B WITH AROME

The goal of this study is to use the large amount of measurements collected during the MAP IOP2B, to validate a new Numerical Weather Prediction system : AROME. We also evaluate AROME by comparison with ALADIN and Meso-NH simulations of this IOP. The AROME 2.5 km results are sensitive to the choice of the coupling model. AROME 2.5 km coupled with AROME 10 km is able in pseudo-operational conditions (long time step and coupled with forecasts) to reproduce the main features of the IOP2B. In this configuration it produces results closest to the Meso-NH reseach model ones

The ALADIN system and its canonical model configurations AROME CY41T1 and ALARO CY40T1

The ALADIN System is a numerical weather prediction (NWP) system developed by the international ALADIN consortium for operational weather forecasting and research purposes. It is based on a code that is shared with the global model IFS of the ECMWF and the ARPEGE model of Meteo-France. Today, this system can be used to provide a multitude of high-resolution limited-area model (LAM) configurations. A few configurations are thoroughly validated and prepared to be used for the operational weather forecasting in the 16 partner institutes of this consortium. These configurations are called the ALADIN canonical model configurations (CMCs). There are currently three CMCs: the ALADIN baseline CMC, the AROME CMC and the ALARO CMC. Other configurations are possible for research, such as process studies and climate simulations. The purpose of this paper is (i) to define the ALADIN System in relation to the global counterparts IFS and ARPEGE, (ii) to explain the notion of the CMCs, (iii) to document their most recent versions, and (iv) to illustrate the process of the validation and the porting of these configurations to the operational forecast suites of the partner institutes of the ALADIN consortium. This paper is restricted to the forecast model only; data assimilation techniques and postprocessing techniques are part of the ALADIN System but they are not discussed here

Characteristics and conditions of production of transient luminous events observed over a maritime storm

International audienceOn the night of 15/16 November 2007, cameras in southern France detected 30 transient luminous events (TLEs) over a storm located in the Corsican region (France). Among these TLEs, 19 were sprites, 6 were halos, and 5 were elves. For 26 of them, a positive “parent” cloud‐to‐ground lightning (P+CG) flash was identified. The peak current of the P+CG flashes for the sprites had an average value of 63 kA and had a maximum value of 125 kA. The flashes for the halos and the elves had average values of 272 and 351 kA, respectively, and they had maximum values of 312 and 384 kA, respectively. No TLEs were detected after negative CG flashes with very large peak currents. Among the 26 P+CG flashes, 23 were located in a stratiform region with reflectivity values lower than 45 dBZ. The CG flashes in this region were classified into two groups according to the time interval separating them from the following flash: one group with values less than 2 s and one with values greater than 2 s. About 79% of all CGs were produced in a sequence of at least two flashes less than 2 s apart. For 65.5% of the sequences, the first flash was positive with an average peak current of 73 kA, while the later +CG flashes in a sequence had much lower peak currents. Several triangulated sprites were found to be shifted from their P+CG flashes by about 10 to 50 km and preferentially downstream. The observations suggest that the P+CG flashes can initiate both sprites and other CG flashes in a storm

The SURFEXv7.2 land and ocean surface platform for coupled or offline simulation of Earth surface variables and fluxes

CC Attribution 3.0 License.Final revised paper also available at http://www.geosci-model-dev.net/6/929/2013/gmd-6-929-2013.pdfInternational audienceSURFEX is a new externalized land and ocean surface platform that describes the surface fluxes and the evolution of four types of surface: nature, town, inland water and ocean. It can be run either coupled or in offline mode. It is mostly based on pre-existing, well validated scientific models. It can be used in offline mode (from point scale to global runs) or fully coupled with an atmospheric model. SURFEX is able to simulate fluxes of carbon dioxide, chemical species, continental aerosols, sea salt and snow particles. It also includes a data assimilation module. The main principles of the organization of the surface are described first. Then, a survey is made of the scientific module (including the coupling strategy). Finally the main applications of the code are summarized. The current applications are extremely diverse, ranging from surface monitoring and hydrology to numerical weather prediction and global climate simulations. The validation work undertaken shows that replacing the pre-existing surface models by SURFEX in these applications is usually associated with improved skill, as the numerous scientific developments contained in this community code are used to good advantage

La campaña experimental BLLAST 2011: Boundary Layer Late Afternoon and Sunset Turbulence

Presentación realizada para las XXXII Jornadas Científicas de la Asociación Meteorológica Española y 13º Encuentro Hispano-Luso de Meteorología celebrados en Alcobendas (Madrid), del 28 al 30 de mayo de 2012

precipitation and lightning activity in thunderstorms,

5-13 juin 200

Surface precipitation electric current produced by convective rains during MAP

This paper presents data from measurements of electric field, precipitation current density, and rainfall parameters performed during the Mesoscale Alpine Program experiment in northern Italy during autumn 1999. Several days of the period provided substantially charged rainfall of both polarities. The average proportions of each polarity are close, but the negative one is slightly larger (54%). Three Doppler radars provided a description of the cells' development and dynamics. A case of a deeply convective cell occurred on 17 September 1999. In this case, the precipitation current density is first positive, reaches more than 100 nA m−2, and changes its polarity when the rainfall is maximum with a value close to 200 mm h−1. We also consider several shallow convective cells passing over the experimental site on 3 October. Two cells among a set of eight did not produce electrical parameter variations although they displayed development and radar reflectivity structure similar to that of the others. The dynamical study shows that the vertical velocity (averaged over 1 km × 1 km mesh) was weaker within these two cells with a value of only 0.5 m s−1 while it reached 1.5 m s−1 within the other cells. Both charge polarities were observed on the rain produced by electrified cells, first the negative one and then the positive one. A very tight correlation between surface electric field and precipitation current is observed out at the surface, displaying the mirror image effect. The ground electric field is due to the cloud charge, in contrast with that carried down to the ground by the rainfall. In order to reproduce the field evolution created by the cell passage, we test different models of charge distribution. A model including a horizontal distribution is found to provide a field evolution in best agreement with the observations. According to this model the net charge of the cloud above the site is chronologically positive and negative, which can be the result of the evacuation of an opposite charge by the rain