scholarly journals Global view of aerosol vertical distributions from CALIPSO lidar measurements and GOCART simulations: Regional and seasonal variations

2010 ◽  
Vol 115 ◽  
Author(s):  
Hongbin Yu ◽  
Mian Chin ◽  
David M. Winker ◽  
Ali H. Omar ◽  
Zhaoyan Liu ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
Global View ◽  
Lidar Measurements ◽  
Vertical Distributions

scholarly journals Seasonal Variations of Phosphorus Species in the Overlying and Pore Waters of the Tuohe River, China

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Qing Xu ◽  
Xiaoping Yu ◽  
Yafei Guo ◽  
Tianlong Deng ◽  
Yu-Wei Chen ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
Yangtze River ◽  
Algal Bloom ◽  
Soluble Reactive Phosphorus ◽  
Pore Waters ◽  
Phosphorus Species ◽  
Dissolved Phosphorus ◽  
Vertical Distributions ◽  
Reactive Phosphorus ◽  
Main Factor

Overlying sediment and pore waters were collected in summer and winter at upstream (Jintang) and downstream (Neijiang) sites of the Tuohe River, which is one of the five largest tributaries of the Yangtze River in China. Phosphorus species, including soluble reactive phosphorus (SRP), soluble unreactive phosphorus (SUP), and total dissolved phosphorus (TDP), and some diagenetic constituents including dissolved Fe(II), Mn(II), and sulfide in overlying and pore waters, were measured systematically. The seasonal variations and vertical distributions of phosphorus species in overlying and pore waters at both sampling sites were obtained to elucidate some aspects of the transport and transformations of phosphorus. Based on the profiles of pore and overlying waters as well as the TDN/TDP data during an algal bloom in 2007, it was clearly demonstrated that phosphorus was the main factor limiting the phytoplankton growth in the Tuohe River.

scholarly journals Observations of the summertime atmospheric pollutants vertical distributions and the corresponding ozone production in Shanghai, China

2017 ◽  
Author(s):  
Chengzhi Xing ◽  
Cheng Liu ◽  
Shanshan Wang ◽  
Ka Lok Chan ◽  
Yang Gao ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Pearson Correlation ◽  
A Priori ◽  
Lower Troposphere ◽  
Sensitivity Study ◽  
Atmospheric Pollutants ◽  
Ozone Production ◽  
Optical Absorption Spectroscopy ◽  
Lidar Measurements ◽  
Vertical Distributions

Abstract. Ground based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) and lidar measurements were performed in Shanghai, China during May 2016 to investigate the summertime atmospheric pollutants vertical distribution. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) and formaldehyde (HCHO) concentrations were retrieved from MAX-DOAS measurement using the Heidelberg Profile (HeiPro) algorithm, while vertical distribution of ozone (O3) was obtained from an ozone lidar. Sensitivity study of the MAX-DOAS aerosol profile retrieval shows that the a priori aerosol profile shape has significant influences on the aerosol profile retrieval. Aerosol profiles retrieved from MAX-DOAS measurements with Gaussian a priori demonstrate the best agreements with simultaneous lidar measurements and vehicle-based tethered-balloon observations among all a priori aerosol profiles. MAX-DOAS measured tropospheric NO2Vertical Column Densities (VCDs) show a good agreement with OMI satellite observations with Pearson correlation coefficient (R) of 0.95. In addition, measurements of the O3 vertical distribution indicate that the ozone productions do not only occur at surface level but also at higher altitudes (about 1.1 km). Planetary boundary layer (PBL) height, horizontal and vertical wind fields information were integrated to discuss the ozone formation at upper altitudes. The results reveal that enhanced ozone concentrations at ground and upper altitudes are not directly related to horizontal and vertical transportations. Similar patterns of O3 and HCHO vertical distributions were observed during this campaign, which implies that the ozone productions near to the surface and at higher altitudes are mainly influenced by the abundance of volatile organic compounds (VOCs) in the lower troposphere.

scholarly journals A height resolved global view of dust aerosols from the first year CALIPSO lidar measurements

2008 ◽  
Vol 113 (D16) ◽  
Author(s):  
Dong Liu ◽  
Zhien Wang ◽  
Zhaoyan Liu ◽  
Dave Winker ◽  
Charles Trepte
Keyword(s):  
First Year ◽  
Dust Aerosols ◽  
Global View ◽  
Lidar Measurements

scholarly journals Lidar Measurements of Dust Aerosols during Three Field Campaigns in 2010, 2011 and 2012 over Northwestern China

Atmosphere ◽  
2018 ◽  
Vol 9 (5) ◽  
pp. 173 ◽  
Author(s):  
Tian Zhou ◽  
Hailing Xie ◽  
Jianrong Bi ◽  
Zhongwei Huang ◽  
Jianping Huang ◽  
...  
Keyword(s):  
Complex Mixture ◽  
Northwestern China ◽  
Maximum Height ◽  
Near Surface ◽  
Dust Aerosols ◽  
High Particle ◽  
Lidar Measurements ◽  
Vertical Distributions ◽  
Field Campaigns ◽  
The Relationship

Ground-based measurements were carried out during field campaigns in April–June of 2010, 2011 and 2012 over northwestern China at Minqin, the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) and Dunhuang. In this study, three dust cases were examined, and the statistical results of dust occurrence, along with physical and optical properties, were analyzed. The results show that both lofted dust layers and near-surface dust layers were characterized by extinction coefficients of 0.25–1.05 km−1 and high particle depolarization ratios (PDRs) of 0.25–0.40 at 527 nm wavelength. During the three campaigns, the frequencies of dust occurrence retrieved from the lidar observations were all higher than 88%, and the highest frequency was in April. The vertical distributions revealed that the maximum height of dust layers typically reached 7.8–9 km or higher. The high intensity of dust layers mostly occurred within the planetary boundary layer (PBL). The monthly averaged PDRs decreased from April to June, which implies a dust load reduction. A comparison of the relationship between the aerosol optical depth at 500 nm (AOD500) and the Angstrom exponent at 440–870 nm (AE440–870) confirms that there is a more complex mixture of dust aerosols with other types of aerosols when the effects of human activities become significant.

scholarly journals Retrieval and evaluation of tropospheric aerosol extinction profiles using MAX-DOAS measurements over Athens, Greece

2020 ◽  
Author(s):  
Myrto Gratsea ◽  
Tim Bösch ◽  
Panos Kokkalis ◽  
Andreas Richter ◽  
Mihalis Vrekoussis ◽  
...  
Keyword(s):  
Optical Absorption Spectroscopy ◽  
Retrieval Algorithm ◽  
Aerosol Extinction ◽  
The Sun ◽  
Tropospheric Aerosol ◽  
Lidar Measurements ◽  
Vertical Distributions ◽  
Term Basis ◽  
Photometric Measurements ◽  
First Time

Abstract. In this study, we report on the retrieval of aerosol extinction profiles from ground-based scattered sunlight multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements, carried out at Athens, Greece. It is the first time that aerosol profiles are retrieved from MAX-DOAS measurements in Athens. The reported aerosol vertical distributions at 477 nm are derived from the oxygen dimer (O4) differential slant column density observations at different elevation angles by applying the BOREAS retrieval algorithm. Four case studies have been selected for validation purposes; the retrieved aerosol profiles and the corresponding aerosol optical depths (AODs) from the MAX-DOAS are compared with lidar extinction profiles and with sun photometric measurements (AERONET observations), respectively. Despite the different approach of each method regarding the retrieval of the aerosol information, the comparison with the lidar measurements at 532 nm reveals a very good agreement in terms of vertical distribution, with r > 0.85 in all cases. The AODs from the MAX-DOAS and the sun-photometer (the latter at 500 nm) show a satisfactory correlation (with r ≈ 0.6 in three out of the four cases). The comparison indicates that the MAX-DOAS systematically underestimates the AOD in the cases of large particles (small Ångström exponent) and for measurements at small relative azimuthal angles between the viewing direction and the Sun. Better agreement is achieved in the morning, at large relative azimuthal angles. Overall, the aerosol profiles retrieved from MAX-DOAS measurements are of good quality; thus, new perspectives are opened up for assessing urban aerosol pollution on a long term-basis in Athens from continuous and uninterrupted MAX-DOAS measurements.

An electromagnetic induction method for monitoring variation in soil moisture in agroforestry systems

Soil Research ◽  
2007 ◽  
Vol 45 (1) ◽  
pp. 63 ◽  
Author(s):  
N. I. Huth ◽  
P. L. Poulton
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Seasonal Variations ◽  
Electromagnetic Induction ◽  
Agroforestry Systems ◽  
Water Extraction ◽  
Spatial And Temporal Patterns ◽  
Induction Method ◽  
Vertical Distributions ◽  
Soil Water Extraction

An understanding of the spatial and temporal patterns of soil water extraction by trees in agroforestry systems has long been seen as an important step towards understanding their functioning. Traditional methods of soil moisture monitoring have been employed with some success but limitations in utilising them efficiently across both time and space have led to restrictions in their use. An electromagnetic induction (EMI) technique has been evaluated and used to study the patterns of soil water extraction from a Grey Vertosol in fallow or cropped fields alongside a Eucalyptus argophloia windbreak near Warra, Qld (26.93°S, 150.93°E). This technique provides methods for minimising error caused by seasonal variations in temperature and the vertical distributions of both soil water and temperature. The calibration developed in this study was successful in describing the observed variations in total soil moisture in the surface 0.9 m of the soil profile (R2 = 0.93, s.e. = 15.3 mm). We conclude that EMI techniques can provide a quick and efficient means for monitoring soil moisture patterns in agroforestry systems when employed under suitable conditions. This paper describes the techniques developed and where they may be employed, the type of information available from the approach, and the likely methods for employing EMI approaches in a wider range of situations.

scholarly journals Observations of the vertical distributions of summertime atmospheric pollutants and the corresponding ozone production in Shanghai, China

2017 ◽  
Vol 17 (23) ◽  
pp. 14275-14289 ◽  
Author(s):  
Chengzhi Xing ◽  
Cheng Liu ◽  
Shanshan Wang ◽  
Ka Lok Chan ◽  
Yang Gao ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Pearson Correlation ◽  
A Priori ◽  
Lower Troposphere ◽  
Atmospheric Pollutants ◽  
Ozone Production ◽  
Optical Absorption Spectroscopy ◽  
Vertical Column ◽  
Lidar Measurements ◽  
Vertical Distributions

Abstract. Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) and lidar measurements were performed in Shanghai, China, during May 2016 to investigate the vertical distribution of summertime atmospheric pollutants. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) and formaldehyde (HCHO) concentrations were retrieved from MAX-DOAS measurements using the Heidelberg Profile (HEIPRO) algorithm, while vertical distribution of ozone (O3) was obtained from an ozone lidar. Sensitivity study of the MAX-DOAS aerosol profile retrieval shows that the a priori aerosol profile shape has significant influences on the aerosol profile retrieval. Aerosol profiles retrieved from MAX-DOAS measurements with Gaussian a priori profile demonstrate the best agreements with simultaneous lidar measurements and vehicle-based tethered-balloon observations among all a priori aerosol profiles. Tropospheric NO2 vertical column densities (VCDs) measured with MAX-DOAS show a good agreement with OMI satellite observations with a Pearson correlation coefficient (R) of 0.95. In addition, measurements of the O3 vertical distribution indicate that the ozone productions do not only occur at surface level but also at higher altitudes (about 1.1 km). Planetary boundary layer (PBL) height and horizontal and vertical wind field information were integrated to discuss the ozone formation at upper altitudes. The results reveal that enhanced ozone concentrations at ground level and upper altitudes are not directly related to horizontal and vertical transportation. Similar patterns of O3 and HCHO vertical distributions were observed during this campaign, which implies that the ozone productions near the surface and at higher altitudes are mainly influenced by the abundance of volatile organic compounds (VOCs) in the lower troposphere.

Seasonal variations in AADSAS applicants

1985 ◽  
Vol 49 (6) ◽  
pp. 445-447
Author(s):  
E Solomon ◽  
D Stoll
Keyword(s):  
Seasonal Variations
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