elib
DLR-Header
DLR-Logo -> http://www.dlr.de
DLR Portal Home | Imprint | Privacy Policy | Contact | Deutsch
Fontsize: [-] Text [+]

Is a scaling factor required to obtain closure between measured and modelled atmospheric O₄ absorptions? An assessment of uncertainties of measurements and radiative transfer simulations for 2 selected days during the MAD-CAT campaign

Wagner, Thomas and Beirle, Steffen and Benavent, Nuria and Bösch, Tim and Chan, Ka Lok and Donner, Sebastian and Dörner, Steffen and Fayt, Caroline and Friess, Udo and Garcia-Nieto, David and Gielen, Clio and González-Bartolome, David and Gomez, Laura and Hendrick, Francoise and Henzing, Bas and Jin, Jun Li and Lampel, Johannes and Ma, Jianzhong and Mies, Kornelia and Navarro, Mónica and Peters, Enno and Pinardi, Gaia and Puentedura, Olga and Puķīte, Janis and Remmers, Julia and Richter, Andreas and Saiz-Lopez, Alfonso and Shaiganfar, Reza and Sihler, Holger and Van Roozendael, Michel and Wang, Yang and Yela, Margarita (2019) Is a scaling factor required to obtain closure between measured and modelled atmospheric O₄ absorptions? An assessment of uncertainties of measurements and radiative transfer simulations for 2 selected days during the MAD-CAT campaign. Atmospheric Measurement Techniques (AMT), 12 (5), pp. 2745-2817. Copernicus Publications. ISSN 1867-1381

[img] PDF - Published version
16MB

Official URL: https://www.atmos-meas-tech.net/12/2745/2019/

Abstract

In this study the consistency between MAX-DOAS measurements and radiative transfer simulations of the atmospheric O4 absorption is investigated on 2 mainly cloud-free days during the MAD-CAT campaign in Mainz, Germany, in summer 2013. In recent years several studies indicated that measurements and radiative transfer simulations of the atmospheric O4 absorption can only be brought into agreement if a so-called scaling factor (<1) is applied to the measured O4 absorption. However, many studies, including those based on direct sunlight measurements, came to the opposite conclusion, that there is no need for a scaling factor. Up to now, there is no broad consensus for an explanation of the observed discrepancies between measurements and simulations. Previous studies inferred the need for a scaling factor from the comparison of the aerosol optical depths derived from MAX-DOAS O4 measurements with that derived from coincident sun photometer measurements. In this study a different approach is chosen: the measured O4 absorption at 360 nm is directly compared to the O4 absorption obtained from radiative transfer simulations. The atmospheric conditions used as input for the radiative transfer simulations were taken from independent data sets, in particular from sun photometer and ceilometer measurements at the measurement site. This study has three main goals: first all relevant error sources of the spectral analysis, the radiative transfer simulations and the extraction of the input parameters used for the radiative transfer simulations are quantified. One important result obtained from the analysis of synthetic spectra is that the O4 absorptions derived from the spectral analysis agree within 1 % with the corresponding radiative transfer simulations at 360 nm. Based on the results from sensitivity studies, recommendations for optimised settings for the spectral analysis and radiative transfer simulations are given. Second, the measured and simulated results are compared for 2 selected cloud-free days with similar aerosol optical depths but very different aerosol properties. On 18 June, measurements and simulations agree within their (rather large) uncertainties (the ratio of simulated and measured O4 absorptions is found to be 1.01±0.16). In contrast, on 8 July measurements and simulations significantly disagree: for the middle period of that day the ratio of simulated and measured O4 absorptions is found to be 0.82±0.10, which differs significantly from unity. Thus, for that day a scaling factor is needed to bring measurements and simulations into agreement. Third, recommendations for further intercomparison exercises are derived. One important recommendation for future studies is that aerosol profile data should be measured at the same wavelengths as the MAX-DOAS measurements. Also, the altitude range without profile information close to the ground should be minimised and detailed information on the aerosol optical and/or microphysical properties should be collected and used. The results for both days are inconsistent, and no explanation for a O4 scaling factor could be derived in this study. Thus, similar but more extended future studies should be performed, including more measurement days and more instruments. Also, additional wavelengths should be included.

Item URL in elib:https://elib.dlr.de/129092/
Document Type:Article
Title:Is a scaling factor required to obtain closure between measured and modelled atmospheric O₄ absorptions? An assessment of uncertainties of measurements and radiative transfer simulations for 2 selected days during the MAD-CAT campaign
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Wagner, ThomasMPI MainzUNSPECIFIED
Beirle, SteffenMPI fuer Chemie, MainzUNSPECIFIED
Benavent, NuriaInstitute of Physical Chemistry Rocasolano (CSIC)UNSPECIFIED
Bösch, TimUniversity of BremenUNSPECIFIED
Chan, Ka LokKa.Chan (at) dlr.deUNSPECIFIED
Donner, SebastianMPI MainzUNSPECIFIED
Dörner, SteffenMPI MainzUNSPECIFIED
Fayt, CarolineBIRA-IASBUNSPECIFIED
Friess, UdoUniv. of Heidelberg, HeidelbergUNSPECIFIED
Garcia-Nieto, DavidInstitute of Physical Chemistry Rocasolano (CSIC)UNSPECIFIED
Gielen, ClioBIRA-IASBUNSPECIFIED
González-Bartolome, DavidINTAUNSPECIFIED
Gomez, LauraINTAUNSPECIFIED
Hendrick, FrancoiseBIRA/IASBUNSPECIFIED
Henzing, BasTNOUNSPECIFIED
Jin, Jun LiCMAUNSPECIFIED
Lampel, JohannesUniversity of HeidelbergUNSPECIFIED
Ma, JianzhongCMAUNSPECIFIED
Mies, KorneliaMPI MainzUNSPECIFIED
Navarro, MónicaINTAUNSPECIFIED
Peters, EnnoUniversity of BremenUNSPECIFIED
Pinardi, GaiaBIRA-IASBUNSPECIFIED
Puentedura, OlgaINTAUNSPECIFIED
Puķīte, JanisMPI MainzUNSPECIFIED
Remmers, JuliaMPI MainzUNSPECIFIED
Richter, AndreasUniv. of Bremen, BremenUNSPECIFIED
Saiz-Lopez, AlfonsoCSIC, Madrid, SpanienUNSPECIFIED
Shaiganfar, RezaMPI MainzUNSPECIFIED
Sihler, HolgerMPI MainzUNSPECIFIED
Van Roozendael, MichelBIRA-IASBUNSPECIFIED
Wang, YangMPI MainzUNSPECIFIED
Yela, MargaritaINTAUNSPECIFIED
Date:May 2019
Journal or Publication Title:Atmospheric Measurement Techniques (AMT)
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:12
Page Range:pp. 2745-2817
Publisher:Copernicus Publications
ISSN:1867-1381
Status:Published
Keywords:MAX-DOAS, O4
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):Vorhaben Spectroscopic Methods in Remote Sensing
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Chan, Ka Lok
Deposited On:23 Sep 2019 11:53
Last Modified:07 Oct 2019 13:07

Repository Staff Only: item control page

Browse
Search
Help & Contact
Information
electronic library is running on EPrints 3.3.12
Copyright © 2008-2017 German Aerospace Center (DLR). All rights reserved.