Direct radiative impacts of atmospheric aerosols on meteorological conditions over Europe
Date
2016-07-07
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Abstract
Kaasaegse atmosfäärifüüsika tähtsaimateks rakendusteks on lähipäevade ilmaprognoos ja tulevikukliima projitseerimine numbriliste mudelite abil. Täpne ilmaprognoos omab suurt majanduslikku väärtust ning aitab äärmuslikes ilmaoludes kaitsta inimeste elusid ja vara. Kliima modelleerimine aitab välja selgitada antropogeenseid mõjusid kliimasüsteemile ja on aluseks kliimamuutuste leevendamise ja kohanemise strateegiate välja töötamisele. Atmosfääriaerosoolid, õhku pihustunud pisikesed vedelad ja tahked osakesed, mõjutavad nii hetkeilma kui ka Maa kliimat. Kuna tuleviku kliimatingimuste hindamisel on kõige suurem määramatus seotud just nimelt aerosoolide mõjudega, on aerosoolide meteoroloogiliste mõjude uurimine väga oluline. Aerosooliosakesed mõjutavad päikese- ja soojuskiirguse levikut atmosfääris ning lisaks ka pilvede omadusi ja sademete teket, kuna aerosooliosakesed on kondensatsioonituumadeks pilvepiiskade moodustumisel. Aerosoolide summaarne mõju Maa kiirgusbilansile on vastassuunaline kasvuhoonegaaside mõjule, s.t. aerosoolid jahutavad kliimat.
Antud doktoritöös uuriti, kuidas tõsta lühiajaliste numbriliste ilmaprognooside täpsust Euroopa kohal tänu aerosoolide otsese kiirgusliku mõju täpsemale arvestamisele. Doktoritöös leiti, et aerosoolidel on oluline mõju aluspinna energiabilansile ning temperatuuri ja niiskuse jaotusele alumises atmosfääris Euroopa kohal ja et neid mõjusid on vaja numbrilises ilmaennustuses prognoosi täpsuse tagamiseks arvesse võtta. Aerosoolide mõju arvestamine tagab päikesekiirguse kiiritustiheduse täpsema prognoosi, mis on vajalik päikeseenergia tootmise planeerimisel. Kui aerosoolide kontsentratsioonid atmosfääris on väga kõrged, tuleks keskmise klimatoloogilise aerosooli mõju arvestamise asemel prognoosi täpsuse tagamiseks arvesse võtta realistlikku (antud hetkele iseloomulikku) aerosooli mõju. Lisaks näidati aerosoolide nõrgendavat mõju üle Balti riikide ja Soome liikunud ekstreemsele konvektiivsele tormile.
The most important applications of modern-day atmospheric physics are numerical weather prediction and projections of the future climate. Accurate weather forecasts provide great economic benefits and help to protect human lives and property. Climate modelling helps to determine anthropogenic influences on climate and it forms the basis for climate change mitigation and adaptation strategies. Atmospheric aerosols, tiny solid and liquid particles suspended in the air, influence both short-term weather conditions and the Earth's climate. It is very important to study aerosol impacts on meteorological conditions because in the projections of future climate the largest uncertainty is related to aerosol impacts. Aerosols influence the shortwave and longwave radiative transfer in the atmosphere and the properties of clouds and the formation of precipitation because aerosol particles serve as cloud condensation nuclei. The net effect of aerosols on the Earth's radiative budget is negative and they offset part of the warming induced by greenhouse gases. In this thesis, increasing of the accuracy of short-term numerical weather forecasts over Europe was investigated by improving the representation of the direct radiative effect of aerosols in an atmospheric model. It was found that aerosols have a considerable influence on the energy budget at the Earth's surface and temperature and humidity distributions in the lower atmosphere over Europe and it is necessary to account for the aerosol impacts in order to provide accurate numerical weather forecasts. Including a better representation of the direct radiative effect of aerosols leads to more accurate forecasts of the surface shortwave fluxes which are also necessary for solar energy applications. During periods with very high aerosol concentrations in the atmosphere, the influence of realistic aerosols should be accounted for. In addition, the weakening of a severe convective storm due to the influence of aerosols was demonstrated in this thesis.
The most important applications of modern-day atmospheric physics are numerical weather prediction and projections of the future climate. Accurate weather forecasts provide great economic benefits and help to protect human lives and property. Climate modelling helps to determine anthropogenic influences on climate and it forms the basis for climate change mitigation and adaptation strategies. Atmospheric aerosols, tiny solid and liquid particles suspended in the air, influence both short-term weather conditions and the Earth's climate. It is very important to study aerosol impacts on meteorological conditions because in the projections of future climate the largest uncertainty is related to aerosol impacts. Aerosols influence the shortwave and longwave radiative transfer in the atmosphere and the properties of clouds and the formation of precipitation because aerosol particles serve as cloud condensation nuclei. The net effect of aerosols on the Earth's radiative budget is negative and they offset part of the warming induced by greenhouse gases. In this thesis, increasing of the accuracy of short-term numerical weather forecasts over Europe was investigated by improving the representation of the direct radiative effect of aerosols in an atmospheric model. It was found that aerosols have a considerable influence on the energy budget at the Earth's surface and temperature and humidity distributions in the lower atmosphere over Europe and it is necessary to account for the aerosol impacts in order to provide accurate numerical weather forecasts. Including a better representation of the direct radiative effect of aerosols leads to more accurate forecasts of the surface shortwave fluxes which are also necessary for solar energy applications. During periods with very high aerosol concentrations in the atmosphere, the influence of realistic aerosols should be accounted for. In addition, the weakening of a severe convective storm due to the influence of aerosols was demonstrated in this thesis.
Description
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Keywords
atmosfäär, aerosoolid, kiirgus, mõjud, kliima, meteoroloogia, Euroopa, atmosphere, aerosols, radiation, impacts, climate, meteorology, Europe