کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1776379 | 1523612 | 2015 | 16 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Analysis of aerosol scattering properties measured by a nephelometer at a coastal-rural site in the Atlantic southwest of the Iberian Peninsula
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فیزیک زمین (ژئو فیزیک)
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Aerosol hemispherical scattering and the backscattering coefficients, Ïsp, Ïbsc, have been measured using a 3-wavelength (450, 550 and 700 nm) integrating nephelometer over two years (January 2006-May 2008) in the coastal area of the Gulf of Cádiz, in the southwest of the Iberian Peninsula. These coefficients have been carefully analyzed starting with the impact of corrections on the measurements of Ïsp: i.e., drift calibration constants do not modify the mean value in our data series. However, the selection of dry data (with RH less than 50%) modifies substantially the number of data and the resulting mean value of Ïsp is now 14% lower, which is compensated when the angular truncation correction is applied. The characterization and features of Ïsp, Ïbsc, and the derived parameters αsp (alpha Ã
ngström exponent) and b (the backscatter ratio) has been analyzed, as annual, seasonal and diurnal evolution. A general statistic based on hourly data gives mean values and standard deviation of Ïsp (500 nm)=48±38 Mmâ1 with a median of 38 Mmâ1, and Ïbsc (500 nm)=5.6±3.8 Mmâ1 with a median of 4.6 Mmâ1. Thus, these values show moderate-low values but with a large range of variation considering the existing measured values over the Iberian Peninsula. The median value of Ïsp (500 nm) is an indicator that events of high aerosol burden are frequent presenting a substantial influence on the daily averages. The alpha Ã
ngström exponent, αsp, derived from the pairs 450/700 nm gives a mean value 1.35±0.54 with a median of 1.47 and with the most frequent value of 1.7, thus indicating the prevalence of medium size particles but with a significant influence of fine particles. The b ratio has the same value for mean and median, 0.12±0.02, showing a decrease with increasing values of Ïsp. Annual and daily cycles have been also analyzed showing the complex behaviour of the optical properties at this coastal site where cold and warn periods show very different characteristics. Besides, the daily cycle is strongly influenced by the breeze conditions. According to the information extracted from the Ïsp-αsp relationship this rural Atlantic site presents prevalence of mixed marine-continental aerosols but with significant influence of local anthropogenic sources. Desert dust particles were also discriminated which are not frequently reported in the data of “in situ” aerosols.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Atmospheric and Solar-Terrestrial Physics - Volume 132, September 2015, Pages 48-63
Journal: Journal of Atmospheric and Solar-Terrestrial Physics - Volume 132, September 2015, Pages 48-63
نویسندگان
Juan F. López, Victoria E. Cachorro, Angel M. de Frutos,