DOI: 10.1016/j.atmosenv.2019.117177
论文题名: Observed aerosol characteristics to improve forward-modelled attenuated backscatter in urban areas
作者: Warren E. ; Charlton-Perez C. ; Kotthaus S. ; Marenco F. ; Ryder C. ; Johnson B. ; Green D. ; Lean H. ; Ballard S. ; Grimmond S.
刊名: Atmospheric Environment
ISSN: 1352-2310
出版年: 2020
卷: 224 语种: 英语
英文关键词: Aerosols
; Backscattering
; Meteorological instruments
; Optical materials
; Parameterization
; Urban growth
; Weather forecasting
; Aerosol optical characteristic
; Automatic lidar and ceilometers
; Extinction-to-backscatter ratio
; Lidar ratio
; Numerical weather prediction models
; Observation networks
; Total number concentrations
; Urban aerosols
; Optical radar
; aerosol
; atmospheric modeling
; backscatter
; lidar
; numerical model
; parameterization
; relative humidity
; urban area
; aerosol
; article
; concentration (parameter)
; England
; humidity
; prediction
; urban area
; visibility
; weather
; England
; London [England]
; United Kingdom
学科: Automatic lidar and ceilometers
; Lidar forward operator
; Lidar ratio
; Urban aerosols
; Urban observation network
中文摘要: Numerical weather prediction (NWP) models often parameterise aerosols to reduce computational needs, while aiming to accurately capture their impact adequately. Increasingly, aerosols are monitored in-situ directly and/or indirectly (e.g. by automatic lidars and ceilometers, ALC). ALC measure the aerosol optical characteristic of attenuated backscatter. This can also be estimated using forward models that combine forecast aerosol and relative humidity to parameterise aerosol physical and optical characteristics. The aerFO is one such forward model, designed to use Met Office NWP model output and parameterisations from the MURK visibility scheme. Given the aerFO-MURK scheme link, assessing the aerFO output could help inform future MURK scheme developments. To identify which parameterised physical and optical aerosol characteristics in the scheme are the most critical in urban settings, aerFO is driven with different in-situ aerosol observations at a background site in central London. Estimated attenuated backscatter is assessed against ALC observations. It is shown that the original MURK scheme parameterisation underestimates the variance of both dry mean volume radius and total number concentration. Representing both the accumulation and coarse mode aerosols in the aerFO reduces the median bias error of estimated attenuated backscatter by 69.1%. Providing more realistic temporal (monthly to hourly) variability of relative mass for different species leads to little improvement, compared to using monthly climatological means. Numerical experiments show that having more realistic estimates of number concentration is more important than providing more accurate values of the dry mean volume radius for the accumulation mode. Hence, improving the parameterisations for number concentration should be a main focus for further development of the MURK scheme. To estimate aerosol attenuated backscatter, the aerFO requires an extinction to backscatter ratio (i.e. the lidar ratio). In addition to forward modelling, the lidar ratio can also be used with ALC attenuated backscatter to calculate aerosol properties estimated in aerosol forecasts. Here, a model is developed that estimates the ratio using in-situ observations of the number size distribution and speciated aerosol masses. The values of lidar ratio derived at the London background site (14–80 sr across selected common lidar wavelengths) compare well to the literature. However, the modelled lidar ratio is unexpectedly correlated to relative humidity. Further, a stronger dependence exists at shorter wavelengths (355 and 532 nm) compared to longer wavelengths (905 and 1064 nm), and is due to the critical relation of lidar wavelength to aerosol size. © 2019 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/160898
Appears in Collections: 气候变化与战略
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作者单位: Department of Meteorology, University of Reading, United Kingdom; Met Office@Reading, United Kingdom; Institut Pierre Simon Laplace (IPSL), France; Met Office, Exeter, United Kingdom; Environmental Research Group (ERG), King's College London, United Kingdom
Recommended Citation:
Warren E.,Charlton-Perez C.,Kotthaus S.,et al. Observed aerosol characteristics to improve forward-modelled attenuated backscatter in urban areas[J]. Atmospheric Environment,2020-01-01,224