Correlation analyses between downward longwave radiation particulate matters,aerosol optical depth,and metrological variables under non-dusty and cloudless conditions     

Maghrabi  Abdullrahman  Alharbi  Badr  Alharbi  Hamoud  Aldosari  Abdulah 《Theoretical and Applied Climatology》2022,148(3-4):1577-1586

Theoretical and Applied Climatology - This study used downward longwave (LW) radiation measurements, air temperature (T), particulate matter (PM) concentrations of fine (PM 2.5) and coarse (PM10)...  相似文献   

Preliminary Results of High-Energy Cosmic Ray Muons as Observed by a Small Multiwire Detector Operated at High Cutoff Rigidity     

Abdullrahnan Maghrabi  Mohammed AlAnazi  A. Aldosari  M. Almuteri 《Journal of Astrophysics and Astronomy》2017,38(1):1

Solar disturbances modulate primary cosmic rays on different time scales. Studying cosmic ray variation is an important subject that attracts scientists from different disciplines. We have constructed and installed (in Riyadh, Saudi Arabia, Rc =14.4 GV) a three-layer small (20 × 20 cm²) MultiWire Chamber (MWC) telescope to study cosmic ray variations and investigate their influence on various atmospheric and environmental processes. Preliminary results obtained from the developed detector are given. The influence of both atmospheric pressure and temperature was studied. Both the temperature and pressure coefficients were calculated and were consistent with those previously obtained. Short-term cosmic ray periodicities, such as the 27-day period, and its two harmonics, have been identified. Sporadic variations caused by some solar activity processes have been inspected. The obtained results from this detector have been compared to the existing 1 m² scintillator detector, as well as to some of the neutron monitors, showing comparable results.  相似文献   

The influence of dust storms on solar radiation data,aerosol properties and meteorological variables in Central Arabian Peninsula     

A. Maghrabi 《International Journal of Environmental Science and Technology》2017,14(8):1643-1650

Dust storms are one of the natural sources for aerosol particles, especially in desert regions. The arid and semi-arid regions around Saudi Arabia are some of the most important sources of global dust. In this paper, we have quantitatively studied the influence of several dust storms on solar radiation components and meteorological variables. Global, direct and diffuse solar radiation data, in addition to measurements of relative humidity, air temperature, precipitable water vapor, aerosol optical depth and an Angstrom exponent for the period between 1999 and 2002, were used for the purpose of this study. During this period, 34 dusty events were selected, and their effects on these parameters were characterized. We have found that, dust storms significantly increase aerosol optical depth and the diffuse radiation and decrease the global and direct solar radiation components and Angstrom exponent. On the other hand, dusty events affect air temperature, relative humidity and precipitable water vapor differently. They intensify these variables in some events and reduce them in others. We have found that the amount of changes in these variables varies from one event to another. Several possibilities, such as the source of the dust storm and the season in which it occurred, have been suggested to explain these variations.  相似文献   

Defects in sodalite-group minerals determined from X-ray-induced luminescence     

Adrian A. Finch  Henrik Friis  Mufeed Maghrabi 《Physics and Chemistry of Minerals》2016,43(7):481-491

The luminescence spectra of a suite of natural sodium framework silicates including four different sodalite variants and tugtupite have been collected during X-ray irradiation as a function of temperature between 20 and 673 K. The origin of the emission bands observed in these samples is attributed to F-centres (360 nm), paramagnetic oxygen defects (400 and 450 nm), S₂ ^? ions (620 nm) and tetrahedral Fe³⁺ (730 nm). Luminescence in the yellow (550 nm) is tentatively attributed to Mn²⁺, and red luminescence in Cr-rich pink sodalite is possibly from Cr³⁺ activation. Sudden reduction in luminescence intensities of emission centres was observed for all minerals in the 60–120 K range. Since it is common to all the sodalite-group minerals, we infer it is a feature of the aluminosilicate framework. Sodalite luminescence has responses from substitutions on the framework (e.g. paramagnetic oxygen defects, Fe³⁺) which give sodalite properties akin to other framework silicates such as feldspar and quartz. However, the presence of the sodalite cage containing anions (such as F-centres, S₂ ^? ions) imparts additional properties akin to alkali halides. The possibility of coupling between Fe³⁺ and S₂ ^? is discussed. The overall luminescence behaviour of sodalite group can be understood in terms of competition between these centre types.  相似文献