Analysis of the vertical structure and size distribution of dust aerosols over the semi-arid region of the Loess Plateau in China

Abstract. Using measurements of dual-wavelength polarisation lidar, particle sizer, and nephelometer from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), the properties of dust aerosol extinction coefficient, optical depth, depolarisation ratio, colour ratio, size distribution, and concentration over the semi-arid region of the Loess Plateau in north-western China are analysed in a case study of dust storms from 16–18 March 2010. The results show that dust aerosols are distributed mostly within the lower layer (below 3.0 km), with the dust aerosol extinction coefficient ranging from 0.1 to 1.0 km−1. The average optical depth and depolarisation ratio are near 0.6 and 0.3, respectively, while the colour ratio ranges from 0.8 to 1.0. The mass size distribution of dust aerosols has two peaks at 0.7 μm and 5.0 μm, respectively, while the number size distribution of dust aerosols is log-normal with a maximum near 0.8 μm. Particles in the fine mode (r ≤ 2.5 μm) are predominant in the dust storm. Their number concentration decreases while those of particles in the moderate (2.5 μm < r ≤ 10.0 μm) and coarse (10.0 μm < r ≤ 20.0 μm) modes increase. Based on Mie theory and the number size distribution of the aerosol, the dust aerosol scattering coefficient and its variation with particle size are calculated and analysed. A fairly close correlation is found with that measured by the nephelometer, for which the correlation coefficients are 0.89 and 0.94, respectively, at 520 and 700 nm. It shows a Gaussian distribution of dust aerosol scattering coefficient against effective diameter, with a fitting coefficient of 0.96 and centre diameter of 5.5 μm. The contribution percentages of aerosol within fine, moderate, and coarse modes to dust aerosol scattering coefficient are 20.95%, 62.93%, and 16.12%, respectively, meaning that PM10 is a dominant factor in the dust aerosol scattering properties.

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A case study of dust aerosol radiative properties over Lanzhou, China

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-2889-2010 ◽

2010 ◽

Vol 10 (2) ◽

pp. 2889-2914 ◽

Cited By ~ 2

Author(s):

L. Zhang ◽

X. Cao ◽

J. Bao ◽

B. Zhou ◽

J. Huang ◽

...

Keyword(s):

Relative Humidity ◽

Extinction Coefficient ◽

Dust Storm ◽

Dust Aerosol ◽

Pm10 Concentration ◽

Radiative Properties ◽

Scattering Coefficient ◽

Aerosol Extinction ◽

Aerosol Scattering ◽

Aerosol Extinction Coefficient

Abstract. The vertical distribution of dust aerosol and its radiative properties are analysed using the data measured by the micropulse lidar, profiling microwave radiometer, sunphotometer, particulate monitor, and nephelometer at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during a dust storm from 27 March to 29 March 2007. The analysis shows that the dust aerosol mainly exists below 2 km in height, and the dust aerosol extinction coefficient decreases with height. The temporal evolution of aerosol optical depth (AOD) during the dust storm is characterized by a sub-maximum at 22:00 (Beijing Time) on 27 March and a maximum at 12:00 on 28 March. The AOD derived by lidar is compared with that obtained by sunphotometer, and shows a good consistency. The PM10 concentration and aerosol scattering coefficient share identical variation trends, and their maximums both appear at 22:00 on 27 March. The aerosol extinction coefficient and relative humidity have the same trends and their maximums appear at identical heights, showing a correlation between extinction coefficient and relative humidity known as aerosol hygroscopicity. Nevertheless, the correlation between aerosol extinction coefficient and temperature cannot be obviously seen. The aerosol extinction coefficient, scattering coefficient, and PM10 concentration present good linear correlations. The correlation coefficients of the aerosol scattering coefficient and PM10 concentration, of aerosol extinction coefficient and PM10 concentration, and of aerosol extinction and scattering coefficient are respectively 0.98, 0.94, and 0.96.

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A case study of dust aerosol radiative properties over Lanzhou, China

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-4283-2010 ◽

2010 ◽

Vol 10 (9) ◽

pp. 4283-4293 ◽

Cited By ~ 21

Author(s):

L. Zhang ◽

X. Cao ◽

J. Bao ◽

B. Zhou ◽

J. Huang ◽

...

Keyword(s):

Relative Humidity ◽

Extinction Coefficient ◽

Dust Storm ◽

Dust Aerosol ◽

Pm10 Concentration ◽

Radiative Properties ◽

Scattering Coefficient ◽

Aerosol Extinction ◽

Aerosol Scattering ◽

Aerosol Extinction Coefficient

Abstract. The vertical distribution of dust aerosol and its radiative properties are analysed using the data measured by the micropulse lidar, profiling microwave radiometer, sunphotometer, particulate monitor, and nephelometer at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during a dust storm from 27 March to 29 March 2007. The analysis shows that the dust aerosol mainly exists below 2 km in height, and the dust aerosol extinction coefficient decreases with height. The temporal evolution of aerosol optical depth (AOD) during the dust storm is characterized by a sub-maximum at 22:00 (Beijing Time), 27 March and a maximum at 12:00, 28 March. The AOD respectively derived by lidar and sunphotometer shows a good consistency. The PM10 concentration and aerosol scattering coefficient share similar variation trends, and their maximums both appear at 22:00, 27 March. The aerosol extinction coefficient and relative humidity have the similar trends and their maximums almost appear at the same heights, which presents a correlation between extinction coefficient and relative humidity known as aerosol hygroscopicity. The relative humidity is related with temperature, and then the temperature will affect the aerosol extinction properties by modifying the relative humidity condition. The aerosol extinction coefficient, scattering coefficient, and PM10 concentration present good linear correlations. The correlation coefficients of the aerosol scattering coefficients of 450, 520, and 700 nm and PM10 concentration, of aerosol extinction coefficient retrieved by lidar at 532 nm and PM10 concentration, and of aerosol extinction and scattering coefficient are respectively 0.98, 0.94, and 0.96.

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Vertical Profiles of Rain Drop-Size Distribution over Tropical Semi-Arid-Region, Kadapa (14.47° N; 78.82° E), India

International Journal of Scientific Engineering and Technology ◽

10.5958/2277-1581.2017.00018.3 ◽

2017 ◽

Vol 6 (6) ◽

pp. 193 ◽

Cited By ~ 1

Author(s):

K. Hemalatha ◽

D. Punyaseshudu

Keyword(s):

Size Distribution ◽

Arid Region ◽

Drop Size ◽

Drop Size Distribution ◽

Vertical Profiles ◽

Rain Drop ◽

Semi Arid Region ◽

Semi Arid

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Screening of Weeds for Vegetation Recovery in a Pasture in the Semi-arid Region of the Loess Plateau in China.

Journal of Weed Science and Technology ◽

10.3719/weed.38.182 ◽

1993 ◽

Vol 38 (3) ◽

pp. 182-189 ◽

Cited By ~ 1

Author(s):

Nobumasa Ichizen ◽

Masaru Ogasawara ◽

Hitoshi Kuramochi ◽

Makoto Konnai ◽

Wataru Sunohara ◽

...

Keyword(s):

Loess Plateau ◽

Arid Region ◽

Vegetation Recovery ◽

The Loess Plateau ◽

Semi Arid Region ◽

Semi Arid

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Variability of Surface Erosion and Particle Size Distribution in Relation to Slope Aspect and Gradient in a Semi-Arid Region in West of Zanjan

Journal of Water and Soil Science ◽

10.29252/jstnar.22.2.1 ◽

2018 ◽

Vol 22 (2) ◽

pp. 1-14

Author(s):

A. R. Vaezi ◽

◽

Z. Bayat ◽

M. Foroumadi ◽

◽

...

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Arid Region ◽

Slope Aspect ◽

Surface Erosion ◽

Semi Arid Region ◽

Semi Arid

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The mid-domain effect of species diversity of mountainous plants is determined by community life form and family flora in a temperate semi-arid region of China

10.7287/peerj.preprints.27386v1 ◽

2018 ◽

Author(s):

Xu Manhou ◽

Wen Jing

Keyword(s):

Species Diversity ◽

Arid Region ◽

Life Form ◽

Community Life ◽

The Loess Plateau ◽

Altitudinal Gradients ◽

The Family ◽

Plant Level ◽

Semi Arid Region ◽

Semi Arid

The mid-domain effect (MDE) is a vital hypothesis to explain altitudinal patterns of species diversity of mountainous plants with different gradients, but it is bounded in terms of its application at the plant level. To verify the MDE hypothesis, we chose a typical mountain with obvious elevation gradients and considerable plant coverage as a study area in the east of the Loess Plateau and partitioned various elevation belts across this mountain. Through measuring the species diversity of arbor, shrub and herb communities in forest ecosystems, we explored altitudinal patterns of species diversity of mountainous plants with different gradients. We determined that the family numbers of the herb and shrub communities, as well as the species diversity of the arbor community, reached their maximums at intermediate elevations. The family numbers of the herb and shrub communities presented unimodal patterns across altitudinal gradients, and the highest values occurred at intermediate elevations. The family number of the arbor community showed a monotonic decreasing pattern, and the importance values of dominant families in the shrub and arbor communities presented unimodal patterns, but the lowest values occurred at intermediate elevations. The species diversity of the herb, shrub and arbor communities conformed to unimodal change patterns following altitudinal gradients, but the greatest diversity occurred at high, low and intermediate elevations, respectively. At higher elevations, weeds and grasses grew well, whereas sedges grew well at lower elevations. With respect to the importance values of different arbor life forms, their responses to altitudinal gradients indicated a certain variation pattern, which was greater for evergreen coniferous arbor species than for deciduous coniferous arbor species and deciduous broad-leaved arbor species. It is concluded that the MDE hypothesis of species diversity for mountainous plants is influenced greatly by the community life form and family flora at the plant level in a temperate semi-arid region of the Loess Plateau, China. This conclusion tests and modifies the MDE hypothesis and can be valuable for fueling prediction of biodiversity models and for the comparison with similar studies in different regions.

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