scholarly journals Study on variations in lidar ratios for Shanghai based on Raman lidar

2020 ◽  
Author(s):  
Tongqiang Liu ◽  
Qianshan He ◽  
Yonghang Chen ◽  
Jie Liu ◽  
Qiong Liu ◽  
...  
Keyword(s):  
Influencing Factors ◽  
Particle Shape ◽  
Strong Dependence ◽  
Raman Lidar ◽  
Height Range ◽  
Air Masses ◽  
Average Value ◽  
Atmospheric Turbidity ◽  
Vertical Distributions ◽  
Variation Characteristics

Abstract. Accurate Lidar ratios (LR) and better understanding of their variation characteristics can not only improve the retrieval accuracy of parameters from elastic lidar, but also play an important role in assessing the impacts of aerosols on the climate. Using the observational data of Raman lidar in Shanghai from 2017 to 2019, the LR at 355 nm were retrieved and their variations and influencing factors were analyzed. Within the height range of 0.5 km–5 km, about 90 % of the LR were distributed in 10 sr–80 sr with an average value of 41.0 ± 22.5 sr, and the LR decreased with the increase of height. The volume depolarization ratios (δ) were positively correlated with LR, and they also decreased with the increase of height, indicating that the vertical distribution of particle shape was one of the influencing factors of the variations of LR with height. LR had a strong dependence on the original source of the air masses. Affected by the aerosol transported from northwest of Shanghai, the average LR was the largest, 44.2 ± 24.7 sr, accompanied by the most irregular particle shape. The vertical distributions of LR were affected by the atmospheric turbidity, with the greater gradient of LR under the clean conditions. The LR above 1 km could be more than 80 sr, when Shanghai was affected by the biomass burning aerosols.

scholarly journals Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

2021 ◽  
Vol 21 (7) ◽  
pp. 5377-5391
Author(s):  
Tongqiang Liu ◽  
Qianshan He ◽  
Yonghang Chen ◽  
Jie Liu ◽  
Qiong Liu ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Particle Shape ◽  
Strong Dependence ◽  
Influence Factors ◽  
Raman Lidar ◽  
Height Range ◽  
Average Value ◽  
Variation Characteristics ◽  
Lidar Ratio ◽  
The Vertical Distribution

Abstract. Accurate lidar ratio (LR) and better understanding of its variation characteristics can not only improve the retrieval accuracy of parameters from elastic lidar, but also play an important role in assessing the impacts of aerosols on climate. Using the observational data of a Raman lidar in Shanghai from 2017 to 2019, LRs at 355 nm were retrieved and their variations and influence factors were analyzed. Within the height range of 0.5–5 km, about 90 % of the LRs were distributed in 10–80 sr with an average value of 41.0 ± 22.5 sr, and the LR decreased with the increase in height. The volume depolarization ratio (δ) was positively correlated with LR, and it also decreased with the increase in height, indicating that the vertical distribution of particle shape was one of the influence factors of the variations in LR with height. LR had a strong dependence on the original source of air masses. Affected by the aerosols transported from the northwest, the average LR was the largest, 44.2 ± 24.7 sr, accompanied by the most irregular particle shape. The vertical distribution of LR was affected by atmospheric turbidity, with the greater gradient of LR under clean conditions. The LR above 1 km could be more than 80 sr, when Shanghai was affected by biomass burning aerosols.

scholarly journals Direct Solar Radiation and Atmospheric Turbidity in Mikołajki in the Years 1971–1980 and 1991–2000

2009 ◽  
Vol 2 (1) ◽  
pp. 19-33
Author(s):  
Joanna Uscka-Kowalkowska
Keyword(s):  
Solar Radiation ◽  
Solar Irradiance ◽  
Direct Solar Radiation ◽  
Spectral Structure ◽  
Solar Constant ◽  
Air Masses ◽  
Atmospheric Turbidity ◽  
The Earth

Abstract The present study deals with the changing amount of incoming direct solar radiation and the optical state of the atmosphere in Mikołajki in the years 1971-1980 and 1991-2000. The highest level of solar irradiance in these two decades occurred on 23rd June 1977 and amounted to 1043.9 W·m-2. Compared to the first decade analysed, the percentage of the solar constant reaching the Earth in the second decade was higher. The spectral structure of the radiation also changed - the share of the shortest waves (λ<525 nm) increased, whereas the amount of waves with a wavelength of 710 nm or more decreased. In both study periods the annual course of solar extinction (expressed in terms of Linke’s turbidity factor) turned out to have been typical, with the highest values in summer and the lowest in winter. In the years 1991-2000, in all seasons, a lower atmospheric turbidity was observed in comparison with the years 1971-1980. The atmospheric turbidity was also analysed with relation to the air masses. In both decades in question the lowest turbidity occurred in arctic air masses and the highest in tropical air masses. An improved optical state of the atmosphere was observed in all considered air masses, though the biggest decrease in turbidity was found in polar air masses, particularly in the polar maritime old air (TLAM2 dropped by 0.75) and polar continental air (by 0.70).

scholarly journals Cloud and Aerosol Spectroscopy with Raman Lidar

2014 ◽  
Vol 31 (9) ◽  
pp. 1946-1963 ◽  
Author(s):  
Jens Reichardt
Keyword(s):  
Single Photon ◽  
Detection System ◽  
Focal Length ◽  
Aerosol Layer ◽  
Raman Lidar ◽  
Backscatter Coefficient ◽  
Height Range ◽  
Cloud Water Content ◽  
New Instrument ◽  
Raman Backscatter

Abstract A spectrometer for height-resolved measurements of the Raman backscatter-coefficient spectrum of water in its gaseous and condensed phases is presented. The spectrometer is fiber coupled to the far-range receiver of the Raman Lidar for Atmospheric Moisture Sensing (RAMSES) of the German Meteorological Service and consists of a Czerny–Turner spectrograph (500-mm focal length) and a 32-channel single-photon-counting detection system based on a multianode photomultiplier. During a typical measurement (transmitter wavelength of 355 nm), the spectrum between 385 and 410 nm is recorded with a spectral resolution of 0.79 nm; the vertical resolution is 15 m and the height range is 15 km. The techniques outlined are those that are applied to calibrate the spectrum measurement and to monitor fluorescence by atmospheric aerosols that have the potential to interfere with the water observation. For the first time, Raman spectra of liquid-water, mixed-phase, and cirrus clouds are reported, and their temperature dependence is investigated by means of band decomposition. The spectrum-integrated condensed-water Raman backscatter coefficient strongly depends on cloud particle volume, but it is not tightly correlated with the cloud optical properties (particle extinction and backscatter coefficient), which implies that retrieval of cloud water content from optical proxies is likely impossible. Aerosol measurements are also discussed. Depending on type, aerosols may show no backscattering in the spectrometer range at all, or a featureless spectrum that stems quite likely from fluorescence. Finally, the example of a cloud forming in an aerosol layer demonstrates that the new instrument not only opens up new perspectives in cloud research but also contributes to studies of cloud–aerosol interaction.

scholarly journals DMS and MSA measurements in the Antarctic boundary layer: impact of BrO on MSA production

2008 ◽  
Vol 8 (1) ◽  
pp. 2657-2694 ◽  
Author(s):  
K. A. Read ◽  
A. C. Lewis ◽  
S. Bauguitte ◽  
A. M. Rankin ◽  
R. A. Salmon ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Austral Summer ◽  
Atmospheric Concentration ◽  
Air Masses ◽  
Average Value ◽  
Number Of Factors ◽  
Spatial Coverage ◽  
Antarctic Boundary Layer ◽  
The Antarctic

Abstract. In situ measurements of dimethyl sulphide (DMS) and methane sulphonic acid (MSA) were made at Halley Station, Antarctica (75°35´S, 26°19W) during February 2004–February 2005 as part of the CHABLIS (Chemistry of the Antarctic boundary layer and the interface with snow) project. DMS was present in the atmosphere at Halley all year (average 38.1±43 pptV) with a maximum monthly average value of 113.6±52 pptV in February 2004 coinciding temporally with a minimum in sea extent. Whilst seasonal variability and interannual variability can be attributed to a number of factors, short term variability appeared strongly dependent on air mass origin and trajectory pressure height. The MSA and derived non-sea salt sulphate (nss-SO42−) measurements showed no correlation with those of DMS (regression R2=0.039, and R2=0.001, respectively) in-line with the complexity of DMS fluxes, conflicting oxidation routes, transport of air masses and variable spatial coverage of both sea-ice and phytoplankton. MSA was generally low throughout the year, with an annual average of 42 ng m−3 (9.8±13.2 pptV), however MSA: nss-SO42− ratios were high implying a dominance of the addition oxidation route for DMS. Including BrO measurements into MSA production calculations demonstrated the significance of BrO on DMS oxidation within this region of the atmosphere in austral summer. Assuming an 80% yield of DMSO from the reaction of DMS+BrO, an atmospheric concentration of BrO equal to 3 pptV increased the calculated MSA production from DMS by a factor of 9 above that obtained when considering only reaction with the hydroxyl radical.

scholarly journals Spatio-temporal variation characteristics of air pollution and influencing factors in Hebei province

2021 ◽  
Vol 36 (2) ◽  
pp. 411
Author(s):  
Zhen-fang HE ◽  
Qing-chun GUO ◽  
Jia-zhen LIU ◽  
Ying-ying ZHANG ◽  
Jie LIU ◽  
...  
Keyword(s):  
Air Pollution ◽  
Temporal Variation ◽  
Influencing Factors ◽  
Hebei Province ◽  
Variation Characteristics ◽  
Spatio Temporal
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