22 research outputs found
Akatemian jalkavÀki: Lapsi, postdoc, pandemia - rakkautta ja rajoituksia
Kun Juhan esikoinen kohtasi isovanhempansa ensi kertaa, niin jaÌrkytyshaÌn siitaÌ syntyi. PaÌaÌlle vuoden ikaÌisenaÌ haÌn oppi juuri vierastamaan vartuttuaan koko pienen ikaÌnsaÌ eristyksillaÌ toisella mantereella. Pandemia iski yllaÌttaÌen kesken isaÌn postdoc-kauden, ja pakotti rajoitteita meidaÌn jokaisen elaÌmaÌaÌn. MyoÌs Kallen esikoinen syntyi maskipakon ollessa huipussaan. HaÌn oppii kuitenkin nopeasti erottamaan hymyt maskien takaa - lapsi sopeutuu haÌikaÌisevaÌn nopeasti
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Accelerated increases in global and Asian summer monsoon precipitation from future aerosol reductions
There is large uncertainty in future aerosol emissions scenarios explored in the Shared Socioeconomic Pathways(SSPs), with plausible pathways spanning a range of possibilities from large global reductions in emissions to 2050 to mod-erate global increases over the same period. Diversity in emissions across the pathways is particularly large over Asia. Rapid anthropogenic aerosol and precursor emission reductions between the present day and the 2050s lead to enhanced increases inglobal and Asian summer monsoon precipitation relative to scenarios with weak air quality policies. However, the effects of aerosol reductions donât persist in precipitation to the end of the 21st century, when response to greenhouse gases dominatesdifferences across the SSPs. The relative magnitude and spatial distribution of aerosol changes is particularly important for South Asian summer monsoon precipitation changes. Precipitation increases here are initially suppressed in SSPs 2-4.5 and5-8.5 relative to SSP 1-1.9 and 3-7.0 when the impact of East Asian emission decreases is counteracted by that due to continuedincreases in South Asian emissions
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Rapidly evolving aerosol emissions are a dangerous omission from near-term climate risk assessments
Anthropogenic aerosol emissions are expected to change rapidly over the coming decades, driving
strong, spatially complex trends in temperature, hydroclimate, and extreme events both near and
far from emission sources. Under-resourced, highly populated regions often bear the brunt of
aerosolsâ climate and air quality effects, amplifying risk through heightened exposure and
vulnerability. However, many policy-facing evaluations of near-term climate risk, including those
in the latest Intergovernmental Panel on Climate Change assessment report, underrepresent aerosolsâ complex and regionally diverse climate effects, reducing them to a globally averaged offset to greenhouse gas warming. We argue that this constitutes a major missing element in societyâs ability to prepare for future climate change. We outline a pathway towards progress and call for greater interaction between the aerosol research, impact modeling, scenario development, and risk assessment communities
Understanding the climate effects of anthropogenic aerosols
Anthropogenic aerosols alter the climate by scattering and absorbing the incoming solar radiation and by modifying cloudsâ optical properties, causing a global cooling or warming effect. Anthropogenic aerosols are partly co-emitted with anthropogenic greenhouse gases, and future climate mitigation actions lead to the decline of anthropogenic aerosolsâ cooling effect. However, the exact cooling effect is still uncertain. Part of this uncertainty is related to the structural differences of current climate models. This work evaluates the present-day anthropogenic aerosol temperature and precipitation effect and factors affecting the model difference. The key objectives of this thesis were: 1) What are the climate effects of present-day anthropogenic aerosols?, 2) What mechanisms drive the model-to-model differences?, and 3) How do future reductions affect local and global climates?
The global models ECHAM6 and NorESM1 were used to evaluate the present-day climate effects with the identical anthropogenic aerosol scheme MACv2-SP. Results reveal that an identical anthropogenic aerosol description does not reduce the uncertainty related to anthropogenic aerosol climate effects, and the difference in the estimated difference is due to model dynamics and oceans. The key mechanism driving the difference in the models was evaluated using data from the Precipitation Driven Model Intercomparison Project (PRMIP). Similar mechanisms drive the model-to-model difference for greenhouse gases and aerosols, where the key drivers are the differences in water vapor, the vertical temperature structure of the atmosphere, and sea ice and snow cover changes. However, on a regional scale, the key drivers differ. Future anthropogenic aerosol effects were evaluated using new CMIP6 data.
This work shows the importance of anthropogenic aerosols for current and future climate change. For a more accurate assessment of climate impacts of anthropogenic aerosols, one needs to also consider remote effects of the local aerosols. The Arctic regions are particularly sensitive to midlatitude aerosols, such as Asian aerosols, which are expected to decline in the next decades. To gain a more accurate estimation of anthropogenic aerosols, it is not sufficient to only focus on composition and geographical distribution of aerosols, as the dynamic response of climate is also important. On global temperature results did not indicate clear aerosols signal, however future temperature development over the Asian regions is modulated by the future Asian aerosol emissions.Ihmisen aiheuttamat pÀÀstöt vaikuttavat ilmastoon monella eri tavalla. Ihmisen aiheuttamien kasvihuonekaasujen lisÀksi ihmisen toiminnasta aiheutuva pienhiukkasten mÀÀrÀn lisÀÀntyminen muuttaa ilmakehÀn koostumusta. TÀllÀ hetikellÀ pienhiukkaset viilentÀvÀt ilmastoa. Ne kuitenkin vaikuttavat suppeammalla alueella kuin kasvihuonekaasut, jonka takia niillÀ on voimakas paikallinen vaikutus. Kiristyneiden ilmanlaatuvaatimusten takia pienhiukkasten mÀÀrÀ on vÀhentynyt nopeasti ja niiden koostumus on muuttunut. TÀmÀn takia pienhiukkasten aiheuttamia vaikutuksia nykyilmastoon ja tulevaisuuteen on tÀrkeÀÀ tutkia. Erityisesti viilentÀvÀn vaikutuksen tutkiminen on olennaista. Kuitenkaan kaikki pienhiukkaset eivÀt laske lÀmpötilaa vaan esimerkiksi musta hiili lÀmmittÀÀ ilmastoa. Kuitenkin pienhiukkasten ilmastovaikutuksiin liitttyy vielÀ paljon epÀvarmuuksia ja niiden tutkiminen on tÀrkeÀÀ, jotta yhteiskunnat pystyvÀt paremmin sopeutumaan pienhiukkasten aiheuttamiin epÀvarmuuksiin.
TÀssÀ tutkimuksessa hyödynnettiin ECHAM6 ja NorESM1 -ilmastomalleja, joissa on keskenÀÀn samanlainen kuvaus ihmisperÀisistÀ pienhiukkasista. Kummassakin mallissa on identtinen kuvaus aerosolien pilvivuorovaikutuksesta. NÀiden avulla tutkittiin, mikÀ on nykypÀivÀn pienhiukkasten ilmastovaikutus. Kasvihuonekaasujen ja erilaisten pienhiukkasten ilmastovaikutuksia sekÀ ilmastomallien vÀlisiÀ eroja tutkittiin kÀyttÀen Precipitation Driven Model Intercomparison Project (PDRMIP) aineistoa. Tulevaisuuden pienhiukkasten ilmastovaikutuksia tutkittiin Climate Model Intercomparison Project phase 6 (CMIP6) aineistosta.
Tutkimuksessa havaittiin, ettÀ vaikka ilmastomallien ihmisperÀisten aerosolien kuvaus oli identtinen, mallit antoivat lievÀsti erilaisia tuloksia. Mallien vÀliset erot eivÀt olleet merkittÀvÀsti pienemmÀt identtisyydestÀ huolimatta kuin epÀidenttisten mallien erot olivat. Ilmastovaikutusten eroihin vaikuttavat ihmisperÀisten aerosolien kuvaukse lisÀksi se, miten meri on kuvattu malleissa ja miten merijÀÀ muuttuu ihmisperÀisten aerosolien vaikutuksesta. Globaalilla tasolla mallien vÀliset erot selittyvÀt erilaisesta vasteesta ilmakehÀn pystyrakenteessa ja merijÀÀssÀ. Vaikka ilmastomalleihin lisÀtÀÀn kasvihuonekaasujen tai aerosolien mÀÀrÀÀ, erot selittyvÀt samoilla tekijöillÀ. Paikallisesti ilmastomallien vÀliset tulokset taas eroavat merkittÀvÀsti myös pilvien erilaisten vaikutusten seurauksena.
Tulevaisuudessa on arvioitu, ettÀ pienhiukkasten pitoisuudet pienenevÀt. TÀmÀ johtuu siitÀ, ettÀ pienhiukkaset syntyvÀt osittain samoista lÀhteistÀ kuin kasvihuonekaasut. Globaalissa lÀmpötilassa ei havaittu merkittÀvÀÀ vaikutusta, mutta lÀhitulevaisuudessa aerosolien vaikutus sadannan muutoksessa on merkittÀvÀ. Aasiassa aerosoleilla on huomattava vaikutus monsuunisateeseen ja lÀmpötilaan.
TÀmÀ tutkimus antaa viitteitÀ siitÀ, ettÀ ilmastomalleissa ihmisperÀisten pienhiukkasten ilmastovaikutuksissa merkittÀvÀÀ on pienhiukkasten mahdollisimman tarkan kuvauksen lisÀksi ilmakehÀn ja meren dynaaminen vaste. MikÀli tulevaisuudessa ihmisperÀisten aerosolien ilmastovaikutuksia halutaan tarkentaa, pelkÀstÀÀn aerosolien mikrofysiikan tarkempi kuvaus ei ole riittÀvÀÀ vaan tarvitaan ymmÀrrystÀ myös ilmakehÀn dynaamisista vasteista
AlijÀÀhtyneiden vesikerrosten tunnistaminen
This research consecrates to methods to identify geometry of low level supercooled liquid cloud layer when the layer is embedded in ice cloud precipitation. Data gathered during, Biogenic Aerosols â Effects on Clouds and Climate, campaign is used in this study. Identification is carried out by studying radar reflectivity and Doppler velocity profile. Method detect local minimum and maximum from radar reflectivity profile. Layer boundaries are compared to Lidar and sounding observations. Results shows that the boundaries of radar reflectivity can be used to estimate geometry and properties of low level supercooled liquid cloud layer.TĂ€mĂ€ tutkimus keskittyy alijÀÀhtyneen vesikerroksen tunnistamiseen monikerroksisista pilvistĂ€. Aineisto on kerĂ€tty Biogenic Aerosols â Effects on Clouds and Climate -mittauskampanjasta ajalta 1.2-12.9.2014. Tutkimuksessa alijÀÀhtynyt vesikerros tunnistettiin tutkimalla tutkan havaitsemaa takaisinsirontaa. Tutkimuksessa havaittiin, ettĂ€ tutkaheijastuksen Ă€killinen pienentyminen tapahtuu alijÀÀhtyneen vesikerroksen ylĂ€puolella, ja ettĂ€ tutkaheijastus alkaa kasvaa kerroksen sisĂ€llĂ€. Paikallinen maksimi havaitaan kerroksen alareunassa. MenetelmĂ€ havaitsee paikallisen minimin sekĂ€ paikallisen maksin tutka heijastuksesta. Tulokset vahvistettiin Lidar- ja sÀÀpallohavainnoilla, joka osoitti alijÀÀhtyneen veden korkeuden. Tulokset osoittivat, ettĂ€ alijÀÀhtynyt vesikerros voidaan tunnistaa tutka mittauksista tĂ€llĂ€ menetelmillĂ€ ja sen ominaisuuksia voidaan tutkia
Understanding the surface temperature response and its uncertainty to CO2, CH4, black carbon, and sulfate
Understanding the regional surface temperature responses to different anthropogenic climate forcing agents, such as greenhouse gases and aerosols, is crucial for understanding past and future regional climate changes. In modern climate models, the regional temperature responses vary greatly for all major forcing agents, but the causes of this variability are poorly understood. Here, we analyze how changes in atmospheric and oceanic energy fluxes due to perturbations in different anthropogenic climate forcing agents lead to changes in global and regional surface temperatures. We use climate model data on idealized perturbations in four major anthropogenic climate forcing agents (CO2, CH4, sulfate, and black carbon aerosols) from Precipitation Driver Response Model Intercomparison Project (PDRMIP) climate experiments for six climate models (CanESM2, HadGEM2-ES, NCAR-CESM1-CAM4, NorESM1, MIROC-SPRINTARS, GISS-E2). Particularly, we decompose the regional energy budget contributions to the surface temperature responses due to changes in longwave and shortwave fluxes under clear-sky and cloudy conditions, surface albedo changes, and oceanic and atmospheric energy transport. We also analyze the regional model-to-model temperature response spread due to each of these components. The global surface temperature response stems from changes in longwave emissivity for greenhouse gases (CO2 and CH4) and mainly from changes in shortwave clear-sky fluxes for aerosols (sulfate and black carbon). The global surface temperature response normalized by effective radiative forcing is nearly the same for all forcing agents (0.63, 0.54, 0.57, 0.61KW 1 m(2)). While the main physical processes driving global temperature responses vary between forcing agents, for all forcing agents the model-to-model spread in temperature responses is dominated by differences in modeled changes in longwave clear-sky emissivity. Furthermore, in polar regions for all forcing agents the differences in surface albedo change is a key contributor to temperature responses and its spread. For black carbon, the modeled differences in temperature response due to shortwave clear-sky radiation are also important in the Arctic. Regional model-to-model differences due to changes in shortwave and longwave cloud radiative effect strongly modulate each other. For aerosols, clouds play a major role in the model spread of regional surface temperature responses. In regions with strong aerosol forcing, the model-to-model differences arise from shortwave clear-sky responses and are strongly modulated by combined temperature responses to oceanic and atmospheric heat transport in the models.Peer reviewe