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Series / Report no.
Open Access
Type
Report
Language
en
Date
1995-03-31
Research Projects
Organizational Units
Journal Issue
Title
Description of the RIVM 2-dimensional stratosphere model
Translated Title
Beschrijving van het RIVM 2-dimensionaal stratosfeermodel
Published in
Abstract
Voor het uitvoeren van assessmentstudies met betrekking tot de stratosfeer en het bestuderen van de invloed van veranderingen in de stratosfeer op de troposfeer en het klimaat, is bij het Laboratorium voor Luchtonderzoek op het RIVM sinds kort een model van de stratosfeer in gebruik. In dit rapport wordt een beschrijving gegeven van het model en worden een aantal simulaties besproken waarmee eigenschappen van het model zijn onderzocht. In de nabije toekomst zal het model worden gebruikt voor het analyseren van de invloed van verschillende scenario's van CFK's, HCFK's and HFK's op ozon in de stratosfeer, UV in de troposfeer, de stralingsforcering op het klimaat en voor het bestuderen van de invloed van veranderingen in de stratosfeer op de troposfeer en het klimaat. Het model, afkomstig van de Universiteit van Cambridge in Engeland, geeft een 2-dimensionale representatie van de atmosfeer van de noord- tot en met de zuidpool en van 0 tot 60 km hoogte. De drie hoofdcomponenten van het model simuleren de volgende processen in de atmosfeer: dynamica, chemie en straling. Deze drie processen hebben een sterke interactie in het model waardoor allerlei terugkoppelingseffecten kunnen worden bestudeerd. De hier beschreven versie van het model maakt gebruik van van tevoren berekende transport velden. Het model beschrijft naast de ozon-, methaan-, stikstof-, chloor- en broomcycli ook het gedrag van antropogene stoffen als bijvoorbeeld de CFK's. Uit de simulaties met het model wordt geconcludeerd dat de grootschalige transportverschijnselen (de Hadley-cellen, de troposfeer-stratosfeer uitwisseling en de Brewer-Dobson-circulatie) in de troposfeer en stratosfeer goed worden gerepresenteerd, evenals de chemische reacties. Waarschijnlijk door een combinatie van factoren wordt het transport in de troposfeer tussen het noordelijk en het zuidelijk halfrond licht onderschat in het model. Het belang van het transport in de stratosfeer blijkt duidelijk uit box-chemie berekeningen. Stratosferisch ozon wordt voornamelijk geproduceerd boven de tropen waarna het naar hogere breedtegraden wordt getransporteerd door de grootschalige Brewer-Dobson-circulatie in de stratosfeer. Hierdoor worden maxima gevonden in de ozonkolom in het voorjaar op gematigde breedten en minima bij de tropen. De overeenstemming tussen gemodelleerde ozonkolommen en satellietmetingen van het TOMS-instrument is goed. De kleine verschillen zijn karakteristiek voor bijna alle stratosfeermodellen. De hydroxyl concentratie in de troposfeer is van groot belang voor de afbraak van veel stoffen (bijv. methaan, koolstofmonoxide, HCFK's, HFK's). Door het vergelijken van scenarioberekeningen van methylchloroform met waargenomen concentraties in de atmosfeer is de afbraak van methylchloroform bestudeerd evenals de hydroxyl concentratie in de troposfeer. Gebleken is dat de totale afbraak van methylchloroform door het hydroxyl in de troposfeer goed met metingen overeenkomt, hetgeen een indicatie is dat de concentratie van methylchloroform, maar ook van HCFK's en van HFK's, in de atmosfeer goed door het model kan worden beschreven. Dit is van groot belang bij scenario studies naar de invloed van HCFK's en HFK's op de aantasting dan wel herstel van de ozonlaag en op het broeikaseffect.<br>
For performing assessment studies on the stratosphere and studying the influence of changes in the stratosphere on the troposphere and climate, the Air Research Laboratory of the RIVM has recently implemented a model of the stratosphere. In this report, a description of the model will be given and a number of simulations describing the behaviour of the model will be discussed. In the near future the model will be used for analyzing the effects of different scenarios of CFCs, HCFCs and HFCs on stratospheric ozone, UV radiation in the troposphere, radiative forcing of climate and for studying the effects of changes in the stratosphere on the troposphere and climate. The model, obtained from the University of Cambridge in the United Kingdom, is a 2-dimensional model of the atmosphere extending from the North to the South poles and from 0 to 60 km altitude. The model's three major components simulate the dynamics, chemistry and radiation in the atmosphere. Since these three processes are strongly linked in the model, interactions between the different processes can be studied. The version of the model described here uses precalculated transport fields. The ozone, methane, nitrogen, chlorine and bromine chemical cycles are simulated in the model as well as the distribution of anthropogenic compounds such as CFCs. We conclude from the first simulations with the model that the large-scale transport (the Hadley cells, the troposphere-stratosphere exchange and the Brewer-Dobson circulation) in the troposphere and stratosphere is well represented, as well as the chemical reactions. A combination of factors is probably responsible for the slight underestimation of the interhemispheric transport in the model. The box chemistry calculations clearly show the importance of transport in the stratosphere. Stratospheric ozone is produced mainly in the tropics and transported to higher latitudes by the large-scale Brewer-Dobson circulation in the stratosphere. This results in maxima in the ozone column at mid-latitudes in spring and minima in the tropics. The agreement between the modelled ozone columns and satellite measurements with the TOMS instrument is good. The small differences are characteristic for almost all stratosphere models. The tropospheric hydroxyl concentration is very important for the destruction of a number of compounds, e.g. methane, carbon monoxide, HCFCs, HFCs. Scenario calculations of methyl chloroform have been performed and compared with observed atmospheric concentrations to obtain information on the destruction of methyl chloroform and of the hydroxyl concentration in the troposphere. The total loss of methyl chloroform in the troposphere agrees very well with measurements. This indicates that the model can simulate the methyl chloroform concentration, but also the concentration of HCFCs and HFCs, in the atmosphere fairly well. This is very important for studying the effects of different scenarios of HCFCs and HFCs on the destruction or recovery of the ozone layer and on the greenhouse effect.<br>
For performing assessment studies on the stratosphere and studying the influence of changes in the stratosphere on the troposphere and climate, the Air Research Laboratory of the RIVM has recently implemented a model of the stratosphere. In this report, a description of the model will be given and a number of simulations describing the behaviour of the model will be discussed. In the near future the model will be used for analyzing the effects of different scenarios of CFCs, HCFCs and HFCs on stratospheric ozone, UV radiation in the troposphere, radiative forcing of climate and for studying the effects of changes in the stratosphere on the troposphere and climate. The model, obtained from the University of Cambridge in the United Kingdom, is a 2-dimensional model of the atmosphere extending from the North to the South poles and from 0 to 60 km altitude. The model's three major components simulate the dynamics, chemistry and radiation in the atmosphere. Since these three processes are strongly linked in the model, interactions between the different processes can be studied. The version of the model described here uses precalculated transport fields. The ozone, methane, nitrogen, chlorine and bromine chemical cycles are simulated in the model as well as the distribution of anthropogenic compounds such as CFCs. We conclude from the first simulations with the model that the large-scale transport (the Hadley cells, the troposphere-stratosphere exchange and the Brewer-Dobson circulation) in the troposphere and stratosphere is well represented, as well as the chemical reactions. A combination of factors is probably responsible for the slight underestimation of the interhemispheric transport in the model. The box chemistry calculations clearly show the importance of transport in the stratosphere. Stratospheric ozone is produced mainly in the tropics and transported to higher latitudes by the large-scale Brewer-Dobson circulation in the stratosphere. This results in maxima in the ozone column at mid-latitudes in spring and minima in the tropics. The agreement between the modelled ozone columns and satellite measurements with the TOMS instrument is good. The small differences are characteristic for almost all stratosphere models. The tropospheric hydroxyl concentration is very important for the destruction of a number of compounds, e.g. methane, carbon monoxide, HCFCs, HFCs. Scenario calculations of methyl chloroform have been performed and compared with observed atmospheric concentrations to obtain information on the destruction of methyl chloroform and of the hydroxyl concentration in the troposphere. The total loss of methyl chloroform in the troposphere agrees very well with measurements. This indicates that the model can simulate the methyl chloroform concentration, but also the concentration of HCFCs and HFCs, in the atmosphere fairly well. This is very important for studying the effects of different scenarios of HCFCs and HFCs on the destruction or recovery of the ozone layer and on the greenhouse effect.<br>
Description
Publisher
Rijksinstituut voor Volksgezondheid en Milieu RIVM
Sponsors
DGM/LE