23 research outputs found
2010. aasta augustitormi analĂŒĂŒs: sirgĂ€ikesetormi dĂŒnaamika modelleerimine HARMONIE mudeliga
http://hdl.handle.net/10062/3055
AtmosfÀÀriaerosoolide otsene kiirguslik mÔju meteoroloogilistele tingimustele Euroopas
VĂ€itekirja elektrooniline versioon ei sisalda publikatsioone.Kaasaegse atmosfÀÀrifĂŒĂŒsika tĂ€htsaimateks rakendusteks on lĂ€hipĂ€evade ilmaprognoos ja tulevikukliima projitseerimine numbriliste mudelite abil. TĂ€pne ilmaprognoos omab suurt majanduslikku vÀÀrtust ning aitab ÀÀrmuslikes ilmaoludes kaitsta inimeste elusid ja vara. Kliima modelleerimine aitab vĂ€lja selgitada antropogeenseid mĂ”jusid kliimasĂŒsteemile ja on aluseks kliimamuutuste leevendamise ja kohanemise strateegiate vĂ€lja töötamisele. AtmosfÀÀriaerosoolid, Ă”hku pihustunud pisikesed vedelad ja tahked osakesed, mĂ”jutavad nii hetkeilma kui ka Maa kliimat. Kuna tuleviku kliimatingimuste hindamisel on kĂ”ige suurem mÀÀramatus seotud just nimelt aerosoolide mĂ”judega, on aerosoolide meteoroloogiliste mĂ”jude uurimine vĂ€ga oluline. Aerosooliosakesed mĂ”jutavad pĂ€ikese- ja soojuskiirguse levikut atmosfÀÀris ning lisaks ka pilvede omadusi ja sademete teket, kuna aerosooliosakesed on kondensatsioonituumadeks pilvepiiskade moodustumisel. Aerosoolide summaarne mĂ”ju Maa kiirgusbilansile on vastassuunaline kasvuhoonegaaside mĂ”jule, s.t. aerosoolid jahutavad kliimat.
Antud doktoritöös uuriti, kuidas tĂ”sta lĂŒhiajaliste numbriliste ilmaprognooside tĂ€psust Euroopa kohal tĂ€nu aerosoolide otsese kiirgusliku mĂ”ju tĂ€psemale arvestamisele. Doktoritöös leiti, et aerosoolidel on oluline mĂ”ju aluspinna energiabilansile ning temperatuuri ja niiskuse jaotusele alumises atmosfÀÀris Euroopa kohal ja et neid mĂ”jusid on vaja numbrilises ilmaennustuses prognoosi tĂ€psuse tagamiseks arvesse vĂ”tta. Aerosoolide mĂ”ju arvestamine tagab pĂ€ikesekiirguse kiiritustiheduse tĂ€psema prognoosi, mis on vajalik pĂ€ikeseenergia tootmise planeerimisel. Kui aerosoolide kontsentratsioonid atmosfÀÀris on vĂ€ga kĂ”rged, tuleks keskmise klimatoloogilise aerosooli mĂ”ju arvestamise asemel prognoosi tĂ€psuse tagamiseks arvesse vĂ”tta realistlikku (antud hetkele iseloomulikku) aerosooli mĂ”ju. Lisaks nĂ€idati aerosoolide nĂ”rgendavat mĂ”ju ĂŒle 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
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Weak average liquid-cloud-water response to anthropogenic aerosols
The cooling of the Earthâs climate through the effects of anthropogenic aerosols on clouds offsets an unknown fraction of greenhouse gas warming. An increase in the amount of water inside liquid-phase clouds induced by aerosols, through the suppression of rain formation, has been postulated to lead to substantial cooling, which would imply that the Earthâs surface temperature is highly sensitive to anthropogenic forcing. Here we provide direct observational evidence that, instead of a strong increase, aerosols cause a relatively weak average decrease in the amount of water in liquid-phase clouds compared with unpolluted clouds. Measurements of polluted clouds downwind of various anthropogenic sourcesâsuch as oil refineries, smelters, coal-fired power plants, cities, wildfires and shipsâreveal that aerosol-induced cloud-water increases, caused by suppressed rain formation, and decreases, caused by enhanced evaporation of cloud water, partially cancel each other out. We estimate that the observed decrease in cloud water offsets 23% of the global climate-cooling effect caused by aerosol-induced increases in the concentration of cloud droplets. These findings invalidate the hypothesis that increases in cloud water cause a substantial climate cooling effect and translate into reduced uncertainty in projections of future climate
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Volcano and ship tracks indicate excessive aerosol-induced cloud water increases in a climate model
Aerosol-cloud interaction is the most uncertain mechanism of anthropogenic radiative forcing of Earthâs climate, and aerosol-induced cloud water changes are particularly poorly constrained in climate models. By combining satellite retrievals of volcano and ship tracks in stratocumulus clouds, we compile a unique observational dataset and confirm that liquid water path (LWP) responses to aerosols are bidirectional, and on average the increases in LWP are closely compensated by the decreases. Moreover, the meteorological parameters controlling the LWP responses are strikingly similar between the volcano and ship tracks. In stark contrast to observations, there are substantial unidirectional increases in LWP in the Hadley Centre climate model, because the model accounts only for the decreased precipitation efficiency and not for the enhanced entrainment drying. If the LWP increases in the model were compensated by the decreases as the observations suggest, its indirect aerosol radiative forcing in stratocumulus regions would decrease by 45%
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Large-scale industrial cloud perturbations confirm bidirectional cloud water responses to anthropogenic aerosols
Aerosols offset a poorly quantified fraction of anthropogenic greenhouse gas warming, and the aerosol impact on clouds is the most uncertain mechanism of anthropogenic climate forcing. Here, observations of a relatively weak average response of liquid cloud water to aerosol perturbations are extended to much larger areas than in previous studies, with the polluted cloud areas covering hundreds by hundreds of kilometers. Polluted clouds detected in satellite images at the global anthropogenic air pollution hot spot of Norilsk, Russia, and at other various major aerosol source regions show close compensation between aerosol-induced cloud water increases and decreases. In the sampled Norilsk cloud perturbations the decrease in LWP offsets 3% of the radiative forcing through the Twomey effect on average. Weak cloud water response on average in large polluted areas is in very good agreement with previous results based on observations of small-scale ship-track-likeindustrial cloud perturbations, helping to reduce the uncertainty associated with the anthropogenic aerosol impacts on clouds
Sensitivity of radiative fluxes to aerosols in the ALADIN-HIRLAM numerical weather prediction system
The direct radiative effect of aerosols is taken into account in many limited-area numerical weather prediction models using wavelength-dependent aerosol optical depths of a range of aerosol species. We studied the impact of aerosol distribution and optical properties on radiative transfer, based on climatological and more realistic near real-time aerosol data. Sensitivity tests were carried out using the single-column version of the ALADIN-HIRLAM numerical weather prediction system, set up to use the HLRADIA simple broadband radiation scheme. The tests were restricted to clear-sky cases to avoid the complication of cloudâradiationâaerosol interactions. The largest differences in radiative fluxes and heating rates were found to be due to different aerosol loads. When the loads are large, the radiative fluxes and heating rates are sensitive to the aerosol inherent optical properties and the vertical distribution of the aerosol species. In such cases, regional weather models should use external real-time aerosol data for radiation parametrizations. Impacts of aerosols on shortwave radiation dominate longwave impacts. Sensitivity experiments indicated the important effects of highly absorbing black carbon aerosols and strongly scattering desert dust
The HARMONIEâAROME Model Configuration in the ALADINâHIRLAM NWP System
The aim of this article is to describe the reference configuration of the convection-permitting numerical
weather prediction (NWP) model HARMONIE-AROME, which is used for operational short-range
weather forecasts in Denmark, Estonia, Finland, Iceland, Ireland, Lithuania, the Netherlands, Norway,
Spain, and Sweden. It is developed, maintained, and validated as part of the shared ALADINâHIRLAM
system by a collaboration of 26 countries in Europe and northern Africa on short-range mesoscale NWP.
HARMONIEâAROME is based on the model AROME developed within the ALADIN consortium.
Along with the joint modeling framework, AROME was implemented and utilized in both northern and
southern European conditions by the above listed countries, and this activity has led to extensive updates to
themodelâs physical parameterizations. In this paper the authors present the differences inmodel dynamics
and physical parameterizations compared with AROME, as well as important configuration choices of the
reference, such as lateral boundary conditions, model levels, horizontal resolution, model time step, as well
as topography, physiography, and aerosol databases used. Separate documentation will be provided for
the atmospheric and surface data-assimilation algorithms and observation types used, as well as a separate
description of the ensemble prediction system based on HARMONIEâAROME, which is called
HarmonEPS
Kliimamuutuste ABC: pÔhjused, mÔjud, lahendused. TeaduspÔhine Ôppematerjal kliimamuutustest
Kliimamuutused kujutavad endast ökosĂŒsteemidele ja inimestele suurt ohtu. Teadus on selge: me
peame tegutsema, et inimtekkelistest kliimamuutustest tingitud riske vÀhendada. Siin astub vahele
aga kliimamuutustealase kirjaoskuse laialdane puudumine Eestis. Kliima kirjaoskus lihtsalt seletatuna, sisaldab endas mĂ”istmist, kuidas kliima mĂ”jutab mind ja kogu ĂŒhiskonda, aga ka seda, kuidas
mina ja meie mÔjutame kliimat. Selles sisaldub ka arusaam kuidas vÀhendada kliimamÔju (ehk kliimamuutusi leevendada) ja suurendada vastupanuvÔimet kliimamuutustele (ehk kliimamuutustega
kohaneda).
Eesti inimeste suur kliimaskeptilisus pĂŒstitab vĂ€ga suured tĂ”kked kliimamuutustega kohanemiseks
ja nende leevendamiseks. Tegutsemiseks ei piisa ĂŒksnes teadmistest, vaid tarvis on ka teadmistele
tuginevaid vÀÀrtusi, hoiakuid ning oskusi. Siit tulebki vajadus selge riikliku poliitika jÀrele, kuidas
inimesi kliimamuutuste vallas harida.
Euroopa majanduspiirkonna rahastatavas projektis âKLIIMATEADLIK - Kliimateadlikkus koolist ĂŒhiskonda: laste, noorte ja Ă”petajate vĂ”imestamine kliimamuutuste mĂ”jude vĂ€hendamiseksâ keskendume kliimahariduse edendamisele Eestis. Teeme seda nii formaalses kui ka mitteformaalses hariduses, et suurendada kliimamuutuste leevendamiseks ja nendega kohanemiseks vajalikke pĂ€devusi.
Meie eesmÀrk on luua Eestis kliimamuutuste haridusprogramm, mis hÔlmab kÔiki haridustasandeid.
Selleks arendame haridusstrateegiaid, loome Ôppematerjale ja toetame Ôpetajaid.
Esiteks selgitasime vÀlja praeguse kliimahariduse olukorra. Vaatasime lÀbi riikliku Ôppekava ning
ainekavad. Selgus, et kliimamuutusi kĂ€sitletakse iseseisva teemana ainult mĂ”ningates loodusainetes. Kuid siingi tutvustatakse kliimat ekslikult kui pelgalt ĂŒht osa kohalikest keskkonnatingimustest.
Puudub globaalse kliimasĂŒsteemi terviklik kĂ€sitlus, mistĂ”ttu on kliimamuutuste teemade teistesse
ainetesse lÔimimine keeruline.
JĂ€rgmine samm oli Ă”petamise olukorra vĂ€ljaselgitamine. AnalĂŒĂŒsisime Eestis kasutatavaid Ă”pikuid
ja korraldasime Ă”petajate kĂŒsitluse. Selgus, et kahjuks ei sisalda kooliĂ”pikud tĂ€napĂ€evast teaduslikku arusaama kliimamuutustest. Ăppematerjalides puuduvad selgitused kliimamuutuste pĂ”hjuste
ja mĂ”jude kohta. Pealegi ei kĂ€sitleta ĂŒldse kliimamuutuste leevendamist ja kohanemist. Ăpetajate
kĂŒsitlus andis ĂŒhelt poolt vĂ€ga positiivse vastukaja, sest valdav osa Ă”petajatest pidas kliimamuutusi
oluliseks teemaks ning oli ka nÔus end neil teemadel harima. Teiselt poolt kurdavad Ôpetajad, et puudu on tÀnapÀevased eestikeelsed Ôppevahendid kliimamuutuste kÀsitlemiseks. Eriti just mitteloodusainete Ôpetajad nendivad, et neil puuduvad teadmised, kuidas kliimaprobleeme Ôppesse lÔimida.
Projekti KLIIMATEADLIK esimene Ă”ppevahend âKliimamuutuste ABCâ pĂŒĂŒab neid tĂŒhikuid tĂ€ita. Siin
on kokku vĂ”etud tĂ€napĂ€evased teaduspĂ”hised arusaamad kliimamuutustest. Ăppematerjal tugineb
Valitsustevahelise kliimamuutuste paneeli (IPCC) ja teiste organisatsioonide kliimaraportitele, kus
on sĂŒnteesitud eelretsenseeritud kliimateadust. Ăppematerjal hĂ”lmab kliimamuutuste pĂ”hjuseid ja
mĂ”jusid koos kliimamuutuste leevendamise ja kohanemisega. Ăppevahendi lĂ”id projektipartnerid
ĂŒhistöös ning seda katsetati 2023. aasta mĂ€rtsis neljal koolitusel Tartus, PĂ€rnus, Narvas ja Tallinnas,
samuti Moodleâi e-Ă”ppekeskkonnas.
âKliimamuutuste ABCâ on kĂ€ttesaadav kĂ”igile huvilistele projekti KLIIMATEADLIK Ă”ppevahendite
lehel kliimatarkused.ut.ee. See on mĂ”eldud kogu Eesti rahvale. Ăppevahend sisaldab mĂ”tlemapanevaid ĂŒlesandeid, videoid ning kokkuvĂ”tlikku teksti, milles on rohkelt viiteid. Teksti saab ka soovi
korral vÀlja printida.
Suur tÀnu kÔigile, kes on selle Ôppevahendi valmimisel kaasa löönud. RÔÔmsat Ôppimist!
Kliimateadlik muudab ĂŒhiskonda, mitte kliimat.
Piia Post ja Velle Toll. September 2023TrĂŒkis valmis projekti âKliimateadlikkus koolist ĂŒhiskonda:
laste, noorte ja Ôpetajate vÔimestamine kliimamuutuste mÔjude
vĂ€hendamiseksâ raames.Projekti rahastatakse Euroopa Majanduspiirkonna
Finantsmehhanismi 2014â2021 programmi âKliimamuutuste
leevendamine ja nendega kohanemineâ avatud taotlusvoorust
âKliimateadlikkuse suurendamine
Opportunistic experiments to constrain aerosol effective radiative forcing
Aerosolâcloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be challenging when meteorological variability also drives both aerosol and cloud changes independently. Natural and anthropogenic aerosol perturbations from well-defined sources provide âopportunistic experimentsâ (also known as natural experiments) to investigate ACI in cases where causality may be more confidently inferred. These perturbations cover a wide range of locations and spatiotemporal scales, including point sources such as volcanic eruptions or industrial sources, plumes from biomass burning or forest fires, and tracks from individual ships or shipping corridors. We review the different experimental conditions and conduct a synthesis of the available satellite datasets and field campaigns to place these opportunistic experiments on a common footing, facilitating new insights and a clearer understanding of key uncertainties in aerosol radiative forcing. Cloud albedo perturbations are strongly sensitive to background meteorological conditions. Strong liquid water path increases due to aerosol perturbations are largely ruled out by averaging across experiments. Opportunistic experiments have significantly improved process-level understanding of ACI, but it remains unclear how reliably the relationships found can be scaled to the global level, thus demonstrating a need for deeper investigation in order to improve assessments of aerosol radiative forcing and climate change