Recent data from ACOSOG Z0011 and NSABP B32 trials suggested no need for axillary lymph node dissection (ALND) in patients with micrometastatic involvement of the sentinel lymph node (SLN). The low ...rate of axillary recurrence was attributed to the axilla coverage by the tangential fields (TgFs) irradiation and systemic therapy. This study aimed to evaluate dose distribution and coverage of the axilla levels I–II and the SLN area.
One hundred and nine patients were analyzed according to three groups: group 1 (50 Gy; n = 18), group 2 (60 Gy; n = 34) and group 3 (66 Gy; n = 57). Patients were treated using the standard (STgF; n = 22) or high (HTgF; n = 87) TgF.
The median doses delivered to level I using HTgF versus STgF were 33 and 20 Gy (P = 0.0001). The mean dose delivered to the SLN area was only 28 Gy. Additionally, the SLN area was totally included in the HTgF in 1 out of 12 patients who had intraoperative clip placement in the SNL area.
TgFs provide a limited coverage of the axilla and the SNLB area. This information should be considered when only TgFs are planned to target the axilla in patients with a positive SLN without ALND. Standardization of locoregional radiotherapy in this situation is urgently needed.
Low-visibility conditions (LVC) are a common cause of air traffic, road, and sailing fatalities. Forecasting those conditions is an arduous challenge for weather forecasters all over the world. In ...this work, a new decision support system is developed based on an analog ensemble (AnEn) method to predict LVC over 15 airports of Morocco for 24 forecast hours. Hourly forecasts from the AROME model of eight predictors were used to select the skillful analogs from 2016 to 2018. The verified hourly observations were used as members of the ensemble. The developed ensemble prediction system (EPS) was assessed over 1 year (2019) as a single-value forecast and as a probabilistic forecast. Results analysis shows that AnEn outperforms persistence and its best performances are perceived generally during night and early-morning lead times. From continuous verification analysis, AnEn forecasting errors are found to be location- and lead-time-dependent and become higher for low-visibility cases. AnEn draws an averaged Centered Root Mean Square Error of about 1500 m for all visibilities, 2000 m for fog and 1500 m for mist. As an EPS, AnEn is under-dispersive for all lead times and draws a positive bias for fog and mist events. For probabilistic verification analysis, AnEn visibility forecasts are converted to binary occurrences depending on a set of thresholds from 200 m to 6000 m by a step of 200 m. It is found that the averaged Heidke Skill Score for AnEn is 0.65 for all thresholds. However, AnEn performance generally becomes weaker for fog or mist events prediction.
Flash floods are common in small Mediterranean watersheds and the alerts provided by real-time monitoring systems provide too short anticipation times to warn the population. In this context, there ...is a strong need to develop flood forecasting systems in particular for developing countries such as Morocco where floods have severe socio-economic impacts. In this study, the AROME (Application of Research to Operations at Mesoscale), ALADIN (Aire Limited Dynamic Adaptation International Development) and WRF (Weather Research and Forecasting) meteorological models are evaluated to forecast flood events in the Rheraya and Ourika basin located in the High-Atlas Mountains of Morocco. The model evaluation is performed by comparing for a set of flood events the observed and simulated probabilities of exceedances for different precipitation thresholds. In addition, two different flood forecasting approaches are compared: the first one relies on the coupling of meteorological forecasts with a hydrological model and the second one is a based on a linear relationship between event rainfall, antecedent soil moisture and runoff. Three different soil moisture products (in-situ measurements, European Space Agency’s Climate Change Initiative ESA-CCI remote sensing data and ERA5 reanalysis) are compared to estimate the initial soil moisture conditions before flood events for both methods. Results showed that the WRF and AROME models better simulate precipitation amounts compared to ALADIN, indicating the added value of convection-permitting models. The regression-based flood forecasting method outperforms the hydrological model-based approach, and the maximum discharge is better reproduced when using the WRF forecasts in combination with ERA5. These results provide insights to implement robust flood forecasting approaches in the context of data scarcity that could be valuable for developing countries such as Morocco and other North African countries.
Surface weather parameters detain high socioeconomic impact and strategic insights for all users, in all domains (aviation, marine traffic, agriculture, etc.). However, those parameters were mainly ...predicted by using deterministic numerical weather prediction (NWP) models that include a wealth of uncertainties. The purpose of this study is to contribute in improving low-cost computationally ensemble forecasting of those parameters using analog ensemble method (AnEn) and comparing it to the operational mesoscale deterministic model (AROME) all over the main airports of Morocco using 5-yr period (2016–2020) of hourly datasets. An analog for a given station and forecast lead time is a past prediction, from the same model that has similar values for selected predictors of the current model forecast. Best analogs verifying observations form AnEn ensemble members. To picture seasonal dependency, two configurations were set; a basic configuration where analogs may come from any past date and a restricted configuration where analogs should belong to a day window around the target forecast. Furthermore, a new predictors weighting strategy is developed by using machine learning techniques (linear regression, random forest, and XGBoost). This approach is expected to accomplish both the selection of relevant predictors as well as finding their optimal weights, and hence preserve physical meaning and correlations of the used weather variables. Results analysis shows that the developed AnEn system exhibits a good statistical consistency and it significantly improves the deterministic forecast performance temporally and spatially by up to 50% for Bias (mean error) and 30% for RMSE (root-mean-square error) at most of the airports. This improvement varies as a function of lead times and seasons compared to the AROME model and to the basic AnEn configuration. The results show also that AnEn performance is geographically dependent where a slight worsening is found for some airports.
In the frame of the research project IOGA4MET, a new ground-based GNSS network is being deployed in the Southwest Indian Ocean (SWIO) since November 2017. This new network opens up for new research ...opportunities in geodesics and atmospheric sciences in this area regularly exposed to natural hazards, and significantly expands the International GNSS System (IGS) network, which only includes eight stations so far in the SWIO. After a description of the current status of IOGA4MET, several examples of regional applications in meteorology (climatology and numerical modeling) and geodesy (monitoring of ground deformations) are presented using data collected in northern Madagascar and small neighboring islands in 2018–2020. The observed water vapor cycle is shown to exhibit different characteristics and important variability at all locations. At the seasonal scale, maximum IWV values are similar everywhere, minimum values decrease away from the equator and a sharp IWV gradient can be noticed during the wet–dry transition period. At this time scale, the seasonal IWV cycle analyzed with the high-resolution NWP system AROME-IO matches observations with little discrepancies. At the diurnal scale, IWV characteristics show different behavior on each side of Madagascar, which emphasizes the important role of this island in driving the regional circulation. Finally, examination of ground displacements measured by GNSS stations in relationship with the ongoing Mayotte seismic-volcanic crisis indicates that ground deformation associated with the current off-shore volcanic activity east of Mayotte does not extend up to 250 km, or is currently too low to be detected in very far field.
ABSTRACT
The 7–8 January 2015 persistent fog episode at Lisbon international airport is analysed. Its persistence was atypical of the local climate (second longest episode since 2004) and caused ...significant air traffic disruptions. Furthermore, the performance of two operational models (European Centre for Medium‐range Weather Forecasts (ECMWF) and Applications of Research to Operations at Mesoscale (AROME)) used at the Portuguese Weather Service is assessed not only for the selected fog episode, but also for the extended winters (November to March) of 2013/2014 and 2014/2015. This episode developed under the following conditions: (1) the occurrence of a strong and persistent midwinter anticyclone over Iberia, driving favourable conditions for the formation of radiation fog; (2) a short interruption of the anticyclonic circulation by a kata‐cold front on the day before, favouring the development of fog/low stratus clouds, which persisted until dawn on 7 January over the Tagus valley; (3) low‐tropospheric easterly/northeasterly winds, favouring the drift of fog patches from the Tagus towards Lisbon. At the nearest grid point to Lisbon airport, both ECMWF and AROME were able to capture fog occurrence, but were unable to predict its persistence throughout the episode. Moreover, both models overestimated the 2 m temperature and dew point depression. Low cloud cover and horizontal visibility from ECMWF revealed higher skill in fog prediction than that derived from AROME. Nonetheless, a modified version of the Fog Stability Index based on AROME was proven to be a more skilful fog predictor, also outperforming other predictors based on ECMWF. These conclusions are also supported by an objective verification over a two‐winter period.
In the Mediterranean region, floods are causing extended damages to the population and infrastructures. In Morocco, only a few studies have been conducted to understand flood processes while the ...vulnerability to floods is high. The goals of this study are to compare two modeling approaches for floods using either lumped or spatial rainfall and also to evaluate hydrological forecast capabilities. The Rheraya research catchment is characterized with steep slopes, altitudes ranging from 1027 to 4167 m, and a strong variability of rainfall. The lumped and distributed models provided similar results and reproduced well a sample of six flood events recorded in 2014. However, the distributed model provided the best estimation of the initial conditions, estimated from the ESA-CCI satellite soil moisture product and the Antecedent Precipitation Index. The validation of the lumped and the distributed models, using ESA-CCI to initialize the models, provides a Nash coefficient of 0.61 and 0.63 respectively. Then, two meteorological forecasts provided by the AROME and ALADIN models were evaluated against observed precipitation to provide a hydrological forecast. The AROME forecast performed better but still with a strong bias compared to observed precipitation. Further research is needed to link quantitative precipitation forecasts with hydrological models in this type of catchment.
This study concerns the impact of microphysics on the HARMONIE-AROME NWP model. In particular, the representation of cloud droplets in the single-moment bulk microphysics scheme is examined in ...relation to fog forecasting. We focus on the shape parameters of the cloud droplet size distribution and recent changes to the representation of the cloud droplet number concentration (CDNC). Two configurations of CDNC are considered: a profile that varies with height and a constant one. These aspects are examined together since few studies have considered their combined impact during fog situations. We present a set of six experiments performed for two non-idealised three-dimensional case studies over the Iberian Peninsula and the North Sea. One case displays both low clouds and fog, and the other shows a persistent fog field above sea. The experiments highlight the importance of the considered parameters that affect droplet sedimentation, which plays a key role in modelled fog. We show that none of the considered configurations can simultaneously represent all aspects of both cases. Hence, continued efforts are needed to introduce relationships between the governing parameters and the relevant atmospheric conditions.
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