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Evaluation of ECMWF-IFS (version 41R1) operational model forecasts of aerosol transport by using ceilometer network measurements

Chan, Ka Lok and Wiegner, Matthias and Flentje, Harald and Mattis, Ina and Wagner, Frank and Gasteiger, Josef and Geiß, Alexander (2018) Evaluation of ECMWF-IFS (version 41R1) operational model forecasts of aerosol transport by using ceilometer network measurements. Geoscientific Model Development (11), pp. 3807-3831. Copernicus Publications. doi: 10.5194/gmd-11-3807-2018. ISSN 1991-959X.

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Official URL: https://www.geosci-model-dev.net/11/3807/2018/


In this paper, we present a comparison of model simulations of aerosol profiles with measurements of the ceilometer network operated by the German Weather Service (DWD) over 1 year from September 2015 to August 2016. The aerosol forecasts are produced by the Copernicus Atmosphere Monitoring Service (CAMS) using the aerosol module developed within the Global and regional Earth-system Monitoring using Satellite and in-situ data (GEMS) and Monitoring Atmospheric Composition and Climate (MACC) projects and coupled into the European Centre for Medium-Range Weather Forecasts Integrated Forecasting System (ECMWF-IFS). As the model output provides mass mixing ratios of different types of aerosol, whereas the ceilometers do not, it is necessary to determine a common physical quantity for the comparison. We have chosen the attenuated backscatter β∗ for this purpose. The β∗ profiles are calculated from the mass mixing ratios of the model output assuming the inherent aerosol microphysical properties. Comparison of the attenuated backscatter averaged between an altitude of 0.2 km (typical overlap range of ceilometers) and 1 km in general shows similar annual average values. However, the standard deviation of the difference between model and observation is larger than the average in 8 out of 12 sites. To investigate possible reasons for the differences, we have examined the role of the hygroscopic growth of particles and the particle shape. Our results show that using a more recent particle growth model would result in a ∼22 % reduction of particle backscatter for sea salt aerosols, corresponding to a 10 % reduction of the total backscatter signal on average. Accounting for nonspherical dust particles in the model would reduce attenuated backscatter of dust particles by ∼30 %. As the concentration of dust aerosol is in general very low in Germany, a significant effect on the total backscatter signal is restricted to dust episodes. In summary, consideration of both effects tends to improve the agreement between model and observations but without leading to a perfect consistency. In addition, a strong Saharan dust event was investigated to study the agreement of the spatiotemporal distribution of particles. It was found that the arrival time of the dust layer and its vertical extent very well agree between model and ceilometer measurements for several stations. This underlines the potential of a network of ceilometers to validate the dispersion of aerosol layers.

Item URL in elib:https://elib.dlr.de/129090/
Document Type:Article
Title:Evaluation of ECMWF-IFS (version 41R1) operational model forecasts of aerosol transport by using ceilometer network measurements
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Chan, Ka Lokka.chan (at) dlr.deUNSPECIFIED
Wiegner, MatthiasLMU-MünchenUNSPECIFIED
Flentje, HaraldDWD, HohenpeißenbergUNSPECIFIED
Mattis, InaDWD, HohenpeißenbergUNSPECIFIED
Wagner, FrankDWD, HohenpeißenbergUNSPECIFIED
Gasteiger, JosefLMU, MünchenUNSPECIFIED
Geiß, AlexanderLMU, MünchenUNSPECIFIED
Date:25 September 2018
Journal or Publication Title:Geoscientific Model Development
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
DOI :10.5194/gmd-11-3807-2018
Page Range:pp. 3807-3831
EditorsEmailEditor's ORCID iD
Publisher:Copernicus Publications
Keywords:ECMWF-IFS, ceilometer, aerosol, lidar, hydroscopic growth
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):Vorhaben Spectroscopic Methods in Remote Sensing (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Chan, Ka Lok
Deposited On:23 Sep 2019 11:42
Last Modified:20 Jun 2021 15:52

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