Forecasting of poor visibility episodes in the vicinity of Tenerife Norte Airport

Aviation safety is a priority that may be compromised by adverse weather conditions. This is the case for poor visibility in the vicinity of airports, which can pose a risk during takeoff and landing. For airports that are prone to fog because of their location, an accurate forecast of poor-visibility episodes is vital. However, the forecasting of low clouds is still a challenge in numerical weather prediction, especially when an airport is near complex terrain for which the use of non-hydrostatic mesoscale models is mandatory. All these factors are present at Tenerife Norte Airport, which is commonly affected by poor visibility from low clouds related to persistent trade winds and moist flows from the Atlantic Ocean. In this paper, several methods for estimating visibility based on mesoscale model outputs are tested. Use of the HARMONIE-AROME model is encouraged because of its excellent performance in the detection of poor-visibility episodes (False Alarm Ratio = 0.34–0.38; Frequency Of Misses = 0.22–0.38, depending on the model version and method used). In addition, the use of satellite application facilities is proposed for the nowcasting of low clouds affecting the airport area. Specifically, we used products that estimate cloud type, cloud top altitude, and integrated water vapor content in the boundary layer. Finally, an application is presented for the monitoring of weather conditions in real time to estimate poor-visibility risk.This work was supported by the Aeronautics Annual Plan 2018 of AEMET

Assessment of HARMONIE-AROME in the simulation of the convective activity associated to a subtropical transition using satellite data

Producción CientíficaSubtropical transition events (STT) are a challenge for forecasting and research due to the hybrid characteristics they give to the cyclones. The ability and skillfulness of the HARMONIE-AROME model to reproduce the cloud structure and convection associated to the October 2014 STT is here evaluated. Brightness temperature, cloud top height and accumulated precipitation are assessed against satellite data using traditional skill scores and object-based techniques specific to forecasting spatial evaluation. The results present differences in the simulation of the cyclone between the periods before and after the transition. They also show a very good performance of the model in the location of the events and a good simulation of the intensity of the variables. The performance is sub-optimal for the estimation of the sizes of the convective objects. Brightness temperature and cloud top heights yield very good results in general, with a slight overestimation in both cases. However, the model struggles to capture the accumulated precipitation. There is scarce work evaluating the HARMONIE-AROME model in this type of events; nevertheless, the results are in line with those produced by the simulations with other numerical models. The overall performance of the model is very adequate, although it might be hindered by the internal stability of the model produced by the deep-convection computation.Agencia Estatal de Investigación (PID2019-105306RB-I00/AEI/10.13039/501100011033)Ministerio de Ciencia e Innovación de España - FPI program (PRE2020-092343

Analysis of the October 2014 subtropical cyclone using the WRF and the HARMONIE-AROME numerical models: Assessment against observations

Subtropical cyclones (STCs) are low-pressure systems characterized by having a thermal hybrid structure and sharing tropical and extratropical characteristics. These cyclones are widely studied due to their harmful impacts, in some cases, similar to those caused by hurricanes or tropical storms. From a numerical modeling point of view, they are considered a challenge on account of their rapid intensification. That is the reason why this paper analyzes the simulations of the STC that occurred in October 2014 near the Canary Islands through two highresolution numerical models: Weather Research and Forecasting (WRF) and HARMONIE-AROME. In this study, the simulations obtained with both models of this STC are analyzed versus different observational data. METAR data are used to validate some surface simulated variables throughout the STC life while soundings are chosen to study the tropospheric behavior. Finally, MSG-SEVIRI satellite brightness temperature is used to be compared to those brightness temperatures simulated by both models to give information of the cloud top spatial structure of this atmospheric system. The 2 m temperature, 2 m dew-point temperature, and 10 m wind speed variables do not show significant deviations when carrying out the validation of both models against the available METAR data. It is outstanding the good results found for the HARMONIE-AROME model when analyzing the temperature sounding for both analyzed dates. Additionally, regarding the wind speed sounding, better results are presented in general by the HARMONIE-AROME model, being the WRF model slightly better during the pre-STC stage. Moreover, the skillfulness of the HARMONIE-AROME model is highlighted when simulating the infrared brightness temperature and cloud distribution compared to the WRF model.This work was partially supported by research projects: PID2019- 105306RB-I00, PCIN-2014-013-C07-04, and PCIN2016-080 (UE ERANET Plus NEWA Project), CGL2016-78702-C2-1-R and CGL2016- 78702-C2-2-R (SAFEFLIGHT project), FEI-EU-17-16 and the two ECMWF Special Projects (SPESMART and SPESVALE). JJGA is supported by the FJC2018-035821 grant and JDF acknowledges the grant supported from the MINECO-FPI program (BES-2017)

Subtropical cyclone formation via warm seclusion development: the importance of surface fluxes

Subtropical cyclones (STCs) are characterized by a thermal hybrid structure with tropical and extratropical features. STCs are considered a numerical modeling challenge because of their rapid intensification. A fundamental part of their strength is derived from diabatic processes associated with convection and heat fluxes from the ocean. This study evaluates the importance of surface turbulent heat fluxes during the transition of an extratropical precursor into a STC. This cyclone evolved embedded within a strong meridional flow, having a Shapiro‐Keyser structure and undergoing a warm seclusion process. To assess the importance of those heat fluxes, two Weather Research and Forecasting simulations were defined considering the presence and absence of those fluxes. Results of both simulations reveal a warm seclusion process, which weakened in absence of the heat fluxes. During the system genesis and in absence of heat fluxes, the wind and rainfall values were increased due to the remarkably intense area of frontogenesis to the northwest. Given these results and the lack of transition in the absence of heat fluxes, the frontal nature of the system was verified. Considering the heat fluxes, the obtained potential vorticity values diminished, reducing wind shear and intensifying convection in the system, which favored its transition into an STC. This study is groundbreaking in that no STC has been linked to a warm seclusion process in the Eastern North Atlantic. Additionally, simulated wind field shows an underestimation in comparison with Atmospheric Motion Vectors, used as observational data so as to give a weight to the wind analysis.This work was partially supported by research projects PCIN-2014-013-C07-04, PCIN2016-080 (UE ERA-NET Plus NEWA Project), CGL2016-78702-C2-1-R, CGL2016-78702-C2-2-R, and CGL2016-81828-REDT and the ECMWF special projects (SPESMART and SPESVALE)

Assessing the performance of the HARMONIE-AROME and WRF-ARW numerical models in North Atlantic Tropical Transitions

Producción CientíficaTropical cyclones (TCs) can develop as a result of the tropical transition (TT) process, which occurs when an extratropical cyclone (EC) begins to exhibit tropical characteristics, forming a TC. In this study, four TT processes that lead to a hurricane structure [Delta (2005), Ophelia (2017), Leslie (2018), and Theta (2020)] are evaluated using two high-resolution numerical models (WRF and HARMONIE-AROME). Both tracks and intensities of the cyclones are assessed by comparing the simulated minimum sea level pressure and maximum wind speed to an observational dataset. Moreover, a spatial verification is performed by comparing the MSG-SEVIRI brightness temperature (BT) and accumulated precipitation (IMERG) to the corresponding simulations accomplished by both models. Analyzing the track results, the WRF model, on average, outstands HARMONIE-AROME. However, it is the HARMONIE-AROME model that performs better than WRF when reproducing the intensity of these cyclones. Concerning the BT spatial validation, HARMONIE-AROME slightly outperformed WRF when reproducing the cyclone's structure but failed when simulating the BT amplitude. Besides, both models achieved a nearly perfect cyclone location. In terms of accumulated precipitation results, the HARMONIE-AROME model overestimates the larger structures while underestimating the smaller ones, whereas the WRF model underestimates the bigger structures, being poorly located by both models. Although it is difficult to establish which numerical model performs better, the overall results show an outstanding of the HARMONIE-AROME model over the WRF model when simulating TT processes.IBERCANES (Project PID2019-105306RB-I00/AEI/10.13039/501100011033)Ministerio de Ciencia e Innovación de España - FPI program (PRE2020-092343

Wind kinetic energy climatology and effective resolution for the ERA5 reanalysis

Producción CientíficaERA5 represents the state of the art for atmospheric reanalyses and is widely used in meteorological and climatological research. In this work, this dataset is evaluated using the wind kinetic energy spectrum. Seasonal climatologies are generated for 30° latitudinal bands in the Northern Hemisphere (periodic domain) and over the North Atlantic area (limited-area domain). The spectra are also assessed to determine the effective resolution of the reanalysis. The results present notable differences between the latitudinal domains, indicating that ERA5 is properly capturing the synoptic conditions. The seasonal variability is adequate too, being winter the most energetic, and summer the least energetic season. The limited area domain results introduce a larger energy density and range. Despite the good results for the synoptic scales, the reanalysis’ spectra are not able to properly reproduce the dissipation rates at mesoscale. This is a source of uncertainties which needs to be taken into account when using the dataset. Finally, a cyclone tropical transition is presented as a case study. The spectrum generated shows a clear difference in energy density at every wavelength, as expected for a highly-energetic status of the atmosphere.Ministerio de Asuntos Económicos y Transformación Digital y Universidad Complutense de Madrid (projects: (PID2019-105306RB-I00 (IBER - CANES), CGL2016-78702 (SAFEFLIGHT), PCIN-2016-080 and FEI-EU-17-16)Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL

Numerical Weather Prediction Applied to Aeronautical Meteorology : Study of Local Hazardous Phenomena

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, leída el 27-11-2020Aviation and meteorology are intrinsically related. Even if the safety level of the industry is indisputable, the sustained growth represents a constant challenge to maintain the standards assumed today. In this task weather hazards are one of the priorities, as some of these still pose alarge risk for aircraft operation. The main objective of this doctoral thesis is to improve the knowledge of numerical weather prediction models when applied to aeronautical meteorology events. This is done by means of the evaluation of four different hazards: mountain wave icing, low visibility, deep convective precipitation and microbursts. These phenomena are linked not only by the disruption they may create to aircraft operation, but also by the fact that they can occur in very local and reduced spatiotemporal domains, which renders them very difficult to predict. The events are analysed using simulations run by a mesoscale atmospheric numerica lmodel, mostly the Weather Research and Forecasting (WRF) model. Different parametrizations and configurations are tested. Several skill scores and validation methods are applied, adapted to each phenomenon. Other nowcasting techniques, not based in numerical weather prediction, are used to support the assessment...La aviación y la meteorología están intrínsecamente relacionadas. A pesar de que los niveles de seguridad operacional de la industria son indiscutibles, el crecimiento sostenido supone un desafío constante para mantener los estándares asumidos a día de hoy. En esta tarea, los peligros relacionados con la meteorología son una de las prioridades, ya que algunos de ellos todavía suponen un gran riesgo para la operación de aeronaves. El objetivo principal de esta tesis doctorales mejorar el conocimiento de la predicción numérica aplicada a eventos de meteorología aeronáutica. El mismo se lleva a cabo a través de la evaluación de cuatro eventos peligrosos diferentes: engelamiento en onda de montaña, baja visibilidad, precipitación por convección profunda y micro bursts. Estos fenómenos están relacionados no solo por la alteración que pueden ocasionar en la operación de aeronaves, sino también por el hecho de que pueden darse endominios espacio-temporales muy reducidos y locales, lo cual los hace muy difíciles de predecir. Los eventos se analizan usando simulaciones realizadas con un modelo atmosférico mesoescalar, mayormente el modelo Weather Research and Forecasting (WRF). Se prueban diferentes parametrizaciones y configuraciones. También se aplican diferentes métodos de validación y criterios de cualificación. La evaluación se complementa con el uso de otras técnicas de nowcasting, no basadas en predicción numérica...Fac. de Ciencias FísicasTRUEunpu

The September 2019 floods in Spain: An example of the utility of satellite data for the analysis of extreme hydrometeorological events

Major floods in Spain in September 9–13, 2019 resulted in seven casualties and massive losses to agriculture, property and infrastructure. This paper investigates the utility of satellite data to: (1) characterize the event when input into a hydrological model, and to provide an accurate picture of the evolution of the floods; and (2) inform meteorologists in real time in order to complement model forecasts. It is shown that the precipitation estimates from the Global Precipitation Measurement (GPM) Core Observatory (GPM-CO, available since 2014) and the merged satellite estimates provide an extraordinary improvement over previous technologies to monitor severe hydrometeorological episodes in near real time. In spite of known biases and errors, these new satellite precipitation estimates can be of broad practical interest to deal with emergencies and long-term readiness, especially for semi-arid areas potentially affected by ongoing global warming. Comparisons of satellite data of the September event with model outputs and more direct observations such as rain gauges and ground radars reinforce the idea that satellites are fundamental for an appropriate management of hydrometeorological events.Funding from projects PID2019-108470RB-C21, PID2019-108470RB-C22 (AEI/FEDER, UE), CGL2016-80609-R, and 1365002970/KMA2018-00721 (Korean Meteorological Agency, Korea) is gratefully acknowledged

A review on the current Status of Numerical Weather Prediction in Portugal 2021: surface–atmosphere interactions

Earth system modelling is currently playing an increasing role in weather forecasting and understanding climate change, however, the operation, deployment and development of numerical Earth system models are extremely demanding in terms of computational resources and human effort. Merging synergies has become a natural process by which national meteorological services assess and contribute to the development of such systems. With the advent of joining synergies at the national level, the second edition of the workshop on Numerical Weather Prediction in Portugal was promoted by the Portuguese Institute for the Sea and Atmosphere, I.P. (IPMA), in cooperation with several Portuguese Universities. The event was hosted by the University of Évora, during the period of 11–12 of November 2021. It was dedicated to surface–atmosphere interactions and allowed the exchange of experiences between experts, students and newcomers. The workshop provided a refreshed overview of ongoing research and development topics in Portugal on surface–atmosphere interaction modelling and its applications and an opportunity to revisit some of the concepts associated with this area of atmospheric sciences. This article reports on the main aspects discussed and offers guidance on the many technical and scientific modelling platforms currently under study.info:eu-repo/semantics/publishedVersio