6533b85ffe1ef96bd12c1305
RESEARCH PRODUCT
Influence of clouds on the spectral actinic flux density in the lower troposphere (INSPECTRO): overview of the field campaigns
Paul S. MonksClaire E. ReevesBrian J. BandyMario BlumthalerPeter WerleJosef SchrederJulian GröbnerStephan ThielTrond Morten ThorsethTrond Morten ThorsethBirger BohnC. TopaloglouB. SchallhartManfred WendischNatalia KouremetiRonald ScheirerRonald ScheirerSebastian SchmidtWolfgang JunkermannEvelyn JäkelR. SchmittArve KyllingGian Paolo GobbiAlkiviadis F. BaisStelios KazadzisR SilbernaglRichard KiftBerit KjeldstadL. AmmannatoBernhard MayerOla EngelsenAnn R. Webbsubject
Atmospheric ScienceAIRBORNEMODEL INTERCOMPARISON IPMMI010504 meteorology & atmospheric sciencesPHOTOCHEMICAL ACTIVITYmedia_common.quotation_subjectFluxPHOTOLYSIS FREQUENCY-MEASUREMENTRadiationAtmospheric sciences01 natural sciencesBROKEN CLOUDlaw.inventionTroposphere010309 opticslcsh:Chemistrylaw0103 physical sciencesddc:550MEASUREMENTSZenithABSORPTION CROSS-SECTIONSmedia_commonRemote sensingMonochromator0105 earth and related environmental sciences[SDU.OCEAN]Sciences of the Universe [physics]/Ocean AtmosphereVERTICAL-DISTRIBUTIONStray lightlcsh:QC1-999UVJSpectroradiometerlcsh:QD1-999Sky13. Climate actionQUANTUM YIELDSEnvironmental science/dk/atira/pure/subjectarea/asjc/1900/1902lcsh:PhysicsAEROSOL EXTINCTIONdescription
Ultraviolet radiation is the key factor driving tropospheric photochemistry. It is strongly modulated by clouds and aerosols. A quantitative understanding of the radiation field and its effect on photochemistry is thus only possible with a detailed knowledge of the interaction between clouds and radiation. The overall objective of the project INSPECTRO was the characterization of the three-dimensional actinic radiation field under cloudy conditions. This was achieved during two measurement campaigns in Norfolk (East Anglia, UK) and Lower Bavaria (Germany) combining space-based, aircraft and ground-based measurements as well as simulations with the one-dimensional radiation transfer model UVSPEC and the three-dimensional radiation transfer model MYSTIC. During both campaigns the spectral actinic flux density was measured at several locations at ground level and in the air by up to four different aircraft. This allows the comparison of measured and simulated actinic radiation profiles. In addition satellite data were used to complete the information of the three dimensional input data set for the simulation. A three-dimensional simulation of actinic flux density data under cloudy sky conditions requires a realistic simulation of the cloud field to be used as an input for the 3-D radiation transfer model calculations. Two different approaches were applied, to derive high- and low-resolution data sets, with a grid resolution of about 100 m and 1 km, respectively. The results of the measured and simulated radiation profiles as well as the results of the ground based measurements are presented in terms of photolysis rate profiles for ozone and nitrogen dioxide. During both campaigns all spectroradiometer systems agreed within ±10% if mandatory corrections e.g. stray light correction were applied. Stability changes of the systems were below 5% over the 4 week campaign periods and negligible over a few days. The J(O1D) data of the single monochromator systems can be evaluated for zenith angles less than 70°, which was satisfied by nearly all airborne measurements during both campaigns. The comparison of the airborne measurements with corresponding simulations is presented for the total, downward and upward flux during selected clear sky periods of both campaigns. The compliance between the measured (from three aircraft) and simulated downward and total flux profiles lies in the range of ±15%. © Author(s) 2008. This work is distributed under the Creative Commons Attribution 3.0 License.
year | journal | country | edition | language |
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2008-03-26 |