Atmospheric modelling

Atmospheric aerosols affect climate change in two ways: they reflect sunlight back to space and they participate in cloud formation. Aerosols and the clouds formed from them slow down the warming of climate but the strength of this cooling effect is yet not known precisely. In addition, aerosols reduce air quality and cause approximately 4 million premature deaths per year. Both climate change and air quality have significant impacts on our lives and therefore the modelling group's emphasis is on aerosols, their effects on clouds and consequently on climate. The group members use models such as ECHAM and UCLALES to investigate aerosol-cloud-interactions and the effects of aerosols on the climate.

Current research topics include:

  • the role of natural aerosol in climate change
  • better representation of natural aerosols in atmospheric models
  • better representation of clouds at both LES and GCM resolutions

 

 

Research highlight: RECON

Refining climate effects of anthropogenic and natural aerosol

Both biogenic carbon and anthropogenic pollutants produce a layer of cooling haze in the atmosphere. They can also increase the amount of sunlight which is reflected back to space by clouds. This means that they can diminsh the warming effect of greenhouse gases. Recent laboratory studies indicate that the cooling effect of biogenic carbon can be stronger than previously anticipated. In this study, by using a comprehensive aerosol-chemistry-climate model, we will test if these finding from laboratory studies can be extrapolated to the global atmosphere. We will also evaluate, how much of the cooling comes from natural biogenic carbon compared to anthropogenic pollutants.
 

Research highlight: COLDCLOUD

Supercooled Water in Mid-level Mixed-Phase Clouds: Microphysics, Dynamics and Global Radiation Balance

Mid-level clouds in the atmosphere are composed of supercooled liquid drops and ice particles. It has been observed, that clouds are not homogeneous, but quite often a layer of liquid water is found at the top of mixed-phase or ice particle cloud. This layer can be optically relatively thick compared to rest of the cloud as it contains a high number concentration of small droplets. Due to a low vertical resolution used in atmospheric models, the separation of cloud layers is not possible, and thus modeled clouds freeze too easily and their effect on atmospheric radiation is underestimated. In this project we develop new methods to parameterize the vertical structure of clouds into a global atmospheric model, and use the new model to estimate the radiative forcing of mid-level clouds and how it is expected to change in the warming atmosphere. Beyond that, we will explore the potential aerosol particles has in modifying the properties of these clouds.
 

People:

Harri Kokkola, PhD, Adj. Prof., Senior Scientist, Head of Group

Ali Afzalifar, PhD(Tech.), Scientist
Innocent Kudzotsa, PhD, Scientist
Thomas Kühn, PhD, Scientist
Anton Laakso, PhD, Scientist
Tero Mielonen, PhD, Adj. Prof., Senior Scientist (twitter: @tmielone)
Juha Tonttila, PhD, Scientist

 

Recent science news from the group:

Climate impact of small particles can be evaluated more accurately than before - new version of aerosol model released

The new model provides more precise data on the formation of organic particulates

A more precise description of the microphysics of radiation fog will improve fog forecasts

The Finnish Meteorological Institute is involved in the development of a new climate model

Gaseous emissions from plants are cooling the climate in the southeastern United States

Assumption of similarity of ice crystals can lead to major errors in satellite observations of clouds

New methods for determining growth of nano-sized particles in the atmosphere