Wind speed vertical distribution at Mt. Graham

The characterization of the wind speed vertical distribution V(h) is fundamental for an astronomical site for many different reasons: (1) the wind speed shear contributes to trigger optical turbulence in the whole troposphere, (2) a few of the astroclimatic parameters such as the wavefront coherence time (tau_0) depends directly on V(h), (3) the equivalent velocity V_0, controlling the frequency at which the adaptive optics systems have to run to work properly, depends on the vertical distribution of the wind speed and optical turbulence. Also, a too strong wind speed near the ground can introduce vibrations in the telescope structures. The wind speed at a precise pressure (200 hPa) has frequently been used to retrieve indications concerning the tau_0 and the frequency limits imposed to all instrumentation based on adaptive optics systems, but more recently it has been proved that V_200 (wind speed at 200 hPa) alone is not sufficient to provide exhaustive elements concerning this topic and that the vertical distribution of the wind speed is necessary. In this paper a complete characterization of the vertical distribution of wind speed strength is done above Mt.Graham (Arizona, US), site of the Large Binocular Telescope. We provide a climatological study extended over 10 years using the operational analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF), we prove that this is representative of the wind speed vertical distribution at Mt. Graham with exception of the boundary layer and we prove that a mesoscale model can provide reliable nightly estimates of V(h) above this astronomical site from the ground up to the top of the atmosphere (~ 20 km).Comment: 12 pages, 9 figures (whereof 3 colour), accepted by MNRAS May 27, 201

Sociolinguistic Analysis of School Failure among High School Students: Marrakesh as a Case Study

The purpose of this study is to record the beliefs/views of teachers and students on the sociolinguistic factors of school failure. The facts of this research are part of a wider research concerning student’s social adequacy having used a questionnaire and the viability of the educational system. The sample used for this research was 30 pupils and 20 teachers from four public high schools in   Marrakesh. The results show that both teachers and students attribute school failure to different sociological and psychological factors. Results and implications of this analysis will be presented at the end of this paper. Some recommendations are presented as well

Thermospheric Neutral Winds Above the Oukaimeden Observatory: Effects of Geomagnetic Activity

International audienceIn the context of space weather, we investigate the effect of geomagnetic activity on Earth's thermosphere above the Oukaimeden Observatory in Morocco (geographic coordinates: 31.206°N, 7.866°W; magnetic latitude: 22.77°N) over 3 years from 2014 to 2016. The observatory is equipped with a Fabry-Perot interferometer (FPI) that provides measurements of thermospheric wind speed. In this study 41 disturbed nights (with SYM-H ≤ -50 nT, Kp ≥ 5) were identified and analyzed. We have characterized the meridional and zonal winds variability and dependence on the solar cycle, during both quiet and disturbed conditions. We have classified the storm time meridional neutral winds into three types of variation. The first type is characterized by traveling atmospheric disturbance (TAD)-induced circulation: the first TAD coming from the north and the second TAD being transequatorial, coming from the south. This type of storm with TAD-induced circulation accounts for 59% of the cases. The second type exhibits only slight discrepancies between the disturbed and quiet night flows. These cases account for 33% of the cases. The third type is characterized by the transequatorial wind in whole the night. This last type accounts for 8% of the cases. Finally, we apply a superposed epoch analysis method on the FPI data, and the effect of each phase of the geomagnetic storm on the wind flow and vertical total electron content VTEC has been quantified

Aerosol columnar characterization in Morocco : ELT prospect

The work presented in this paper focuses on site testing in terms of aerosol loadings where ground based measurements are essential. In our case they are materialized by the aerosol optical thickness (AOT) and are provided by the AERONET (Aerosol Robotic Network) network from four stations, Dakhla and Marrakech in Morocco and Santa-Cruz and Izana in the Canary Islands. To fully scan all the area of the Moroccan territories, satellite measurements are certainly the most efficient way. We used the most popular and reliable products. TOMS (Total Ozone Mapping Spectrometer) aerosol index (AI) provided by both TOMS Earth Probe and TOMS OMI (Ozone Monitoring Instrument) along with aerosol optical thicknesses provided by MODIS (Moderate Resolution Imaging Spectroradiometer) and MISR (Multiangle Imaging Spectroradiometer) instruments, onboard Terra platform. The idea is to compare sensing capabilities of each instrument in the region under study, in order to know which is suitable for a given place and when. For that purpose linear regression analysis were performed between satellite data and AERONET observations. Good correlations were observed with the Pearson correlation coefficient, R, varying from 0.68 to 0.92 for MODIS, MISR and TOMS OMI, and from 0.54 to 0.74 for TOMS EP. A ten years analysis of the TOMS EP index has been performed with a calibration of the aerosol index into TOMS retrieved aerosol optical thickness in the area of interest (Morocco and Canary Islands) and an inter-comparison with the other products was achieved. In the frame of the ELT (Extremely Large Telescope) project prospect, once the appropriate satellite instrument have been chosen and the area scanned, the next step would be to scan aerosol loadings at higher altitude locations. Since vertical d istribution of aerosol optical thickness and microphysical properties are not well understood and modelized, we used the relationships related to Izana (Izana's altitude is 2367 m), as a first attempt, to extrapolate the aerosol optical thickness at higher locations in the Moroccan mountains. Izana and Santa-Cruz very close to each other (30 Km) are located in the same satellite pixel and then have the same satellite (AOT) or (AI) whereas AERONET gives very distinct aerosol optical depths. A good linear correlation (R=0.92) has been observed between the AERONET aerosol optical depths at Izana and Santa-Cruz. The ratio AODSanta-Cruz/AODIz ana has a seasonal behavior, reaches the average of 4.5 in winter and 2 in summer time and the subtraction of the aerosol optical thicknesses has an average of 1.3. Finally we retrieved the aerosol optical thickness at Oukaimeden: a Moroccan observatory located at 2700 m above sea level, and about 70 km from Marrakech city. We then converted the aerosol optical depth into astronomical light extinction and compare with previous records measured at the observatory

First characterization of Jbel Aklim in Moroccan Anti-Atlas as a potential site for the E-ELT

Context. In the framework of the European Extremely Large Telescope project (E-ELT), a survey of prospective sites was launched by the European Southern Observatory (ESO) to select a site to host the next generation of optical telescopes of 42 m diameter, i.e., the E-ELT. The Moroccan Anti-Atlas (Jbel Aklim) was selected as one of these sites. Aims. We present an analysis of meteorological parameters and seeing measurements at Aklim, the Moroccan prospective site of the E-ELT project. Methods. We initiated a preliminary campaign to measure the astronomical seeing at Jbel Aklim using a differential image motion monitor (DIMM) instrument. We installed a weather station 2 m above the ground level to measure meteorological parameters such as temperature, relative humidity, pressure, wind speed, and wind direction. Results. We present data obtained by the DIMM monitor during 105 nights. The median and mean values of the seeing for the entire period of observation are 0.72′′ and 0.79′′, respectively, with a standard deviation of 0.31′′. The best value of the seeing obtained during this period is 0.30′′. A seasonal analysis of meteorological parameters are presented. We also used data from the National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis database (NCEP/NCAR) to derive more information about the long-term evolution of atmospheric parameters at Aklim site. Conclusions. Our preliminary results indicate that Aklim has indeed good conditions for conducting astronomical observations and could be a site to host a future astronomical observatory, even of E-ELT dimensions

Meteorological profiles and optical turbulence in the free atmosphere with NCEP/NCAR data at Oukaïmeden I. Meteorological parameters analysis and tropospheric wind regimes

International audienc

Thermospheric Neutral Wind Measurements and Investigations across the African Region—A Review

This paper briefly reviews studies of thermospheric neutral wind dynamics over the African region. The literature includes a review of the observations of neutral winds over five African locations using the Fabry–Perot Interferometer (FPI), and the comparison between the FPI observations and predictions of the horizontal wind model (HWM-14). So far, there are reports of FPI thermospheric wind measurements in South Africa and Morocco representing the mid-latitude regions in the southern and northern hemispheres, respectively. Within the low latitudes, FPI instruments are installed in the Ivory Coast, Ethiopia, and Nigeria. For the literature reviewed, the years covered in the FPI data are 2018–2019 (South Africa), 2016–2017 (Nigeria), 2015–2016 (Ethiopia), 2013–2016 (Morocco), and 1994–1995 (Ivory Coast). Overall, the HWM-14 reproduces the climatological behavior of the meridional and zonal winds, with varying levels of fidelity for the different regions. The HWM-14 is more accurate in the stations located in the northern hemisphere of the African region; a result attributed to the presence of data during the development of this empirical model