A5055806487- Atmospheric aerosols and clouds
- Atmospheric chemistry and aerosols
- Climate variability and models
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Cryospheric studies and observations
- Meteorological Phenomena and Simulations
- Arctic and Antarctic ice dynamics
- Aeolian processes and effects
- Climate change and permafrost
- Climate Change Policy and Economics
- Radiative Heat Transfer Studies
- Plant Water Relations and Carbon Dynamics
- Urban Heat Island Mitigation
- Winter Sports Injuries and Performance
- Precipitation Measurement and Analysis
- Tree-ring climate responses
- Geology and Paleoclimatology Research
- Peatlands and Wetlands Ecology
- Soil Carbon and Nitrogen Dynamics
- Polar Research and Ecology
- Air Quality and Health Impacts
- Irrigation Practices and Water Management
- Tropical and Extratropical Cyclones Research
- Icing and De-icing Technologies
Finnish Meteorological Institute
2016-2025
University of Helsinki
1996-2012
Dalhousie University
2003-2004
Abstract To use the Monte Carlo Independent Column Approximation method for computing domain‐average radiative fluxes in large‐scale atmospheric models (LSAMs), a is needed generating cloudy subcolumns within LSAM columns. Here, stochastic cloud generator introduced to produce subcolumns. The creates field on column‐by‐column basis using information about layer fraction, vertical overlap of fraction and condensate adjacent layers, density functions describing horizontal variations water...
Abstract. The global aerosol-climate model ECHAM5-HAM was modified to improve the representation of new particle formation in boundary layer. Activation-type nucleation mechanism introduced produce observed rates lower troposphere. A simple and computationally efficient for biogenic secondary organic aerosol (BSOA) implemented. Here we study sensitivity cloud droplet number concentrations (CDNC) these additions. significantly increases Increased have a significant effect also on therefore...
We present results from Phase I of the Continual Intercomparison Radiation Codes (CIRC), intended as an evolving and regularly updated reference source for evaluation radiative transfer (RT) codes used in global climate models other atmospheric applications. CIRC differs previous intercomparisons that it relies on observationally validated catalog cases. The seven baseline cases, five cloud free two with overcast liquid clouds, are built around observations by Atmospheric Measurements...
The primary purpose of this study is to assess the performance 1D solar radiative transfer codes that are used currently both for research and in weather climate models. Emphasis on interpretation handling unresolved clouds. Answers sought following questions: (i) How well do interpret handle columns information pertaining partly cloudy atmospheres? (ii) Regardless adequacy their assumptions about clouds, perform as intended? One clear-sky two plane-parallel, homogeneous (PPH) overcast cloud...
Abstract The Monte Carlo Independent Column Approximation (McICA) computes domain‐average, broadband radiative flux profiles within conventional global climate models (GCMs). While McICA is unbiased with respect to the full ICA, it generates, as a by‐product, random noise. If this by‐product leads statistically significant impacts on GCM simulations, could limit usefulness of McICA. This paper assesses impact McICA's noise six GCMs. To end, GCMs performed ensembles 14‐day long simulations...
Abstract. A comprehensive comparison of more than 70 000 synchronous 1 min aerosol optical depth (AOD) data from three Global Atmosphere Watch precision-filter radiometers (GAW-PFR), traceable to the World AOD reference, and 15 Aerosol Robotic Network Cimel (AERONET-Cimel), calibrated individually with Langley plot technique, was performed for four common or “near” wavelengths, 380, 440, 500 870 nm, in period 2005–2015. The goal this study is assess whether, despite marked technical...
Abstract The role of aerosols remains a major uncertainty for climate and change. For the direct radiative forcing by mineral aerosols, in refractive index m has been regarded as most important error source, while impact aerosol non‐sphericity considered minor issue is neglected models. Here, errors caused spherical particle approximation (SPA) are evaluated comparing fluxes based on (i) Mie simulations (ii) laboratory measurements optical properties. Furthermore, they contrasted with...
Abstract Future seasonal changes in surface incident solar radiation and relative humidity (RH) over Europe adjacent ocean areas were assessed based on phase 3 of the Coupled Model Intercomparison Project (CMIP3) model ensemble. Under A1B scenario, by 2070–99, summertime is projected to increase 5%–10% central southern Europe. In winter, decreases most northern eastern 5%–15%. RH drops summer European inland 8%–12%, whereas winter a small 2%–3% for northeastern spring, change an intermediate...
Abstract. We have measured spectral albedo, as well ancillary parameters, of seasonal European Arctic snow at Sodankylä, Finland (67°22' N, 26°39' E). The springtime intensive melt period was observed during the Snow Reflectance Transition Experiment (SNORTEX) in April 2009. upwelling and downwelling irradiance, 290–550 nm with a double monochromator spectroradiometer, revealed albedo values ~0.5–0.7 for ultraviolet visible range, both under clear sky variable cloudiness. During most...
Abstract. This study assesses the change in anthropogenic aerosol forcing from mid-1970s to mid-2000s. Both decades had similar global-mean optical depths but substantially different global distributions. For both years, we quantify (i) spread due model-internal variability and (ii) among models. Our assessment is based on new ensembles of atmosphere-only simulations with five state-of-the-art Earth system Four these models will be used sixth Coupled Model Intercomparison Project (CMIP6;...
Abstract. The global potential for collecting usable water from dew on an artificial collector sheet was investigated by utilizing 34 years of meteorological reanalysis data as input to a formation model. Continental found be frequent and common, but daily yields were mostly below 0.1 mm. Nevertheless, some water-stressed areas such parts the coastal regions northern Africa Arabian Peninsula show large-scale harvesting, yearly yield may reach up 100 L m−2 commonly used polyethylene foil....
Abstract. The regional climate model REMO was coupled with the FLake lake to include an interactive treatment of lakes. Using this new version, Fenno-Scandinavian and characteristics were studied in a set 35-year hindcast simulations. Additionally, sensitivity tests related parameterization snow albedo conducted. Our results show that overall version improves representation terms 2 m temperature precipitation, but downside is existing wintertime cold bias enhanced. surface water temperature,...
Abstract. The primary goal of this paper is to present a model snow surface albedo accounting for small-scale roughness effects. based on photon recollision probability, and it can be combined with existing bulk volume models, such as Two-streAm Radiative TransfEr in Snow (TARTES). fed situ measurements from plate profile laser scanner data, evaluated by comparing the computed albedos observations. It provides closer results empirical values than volume-scattering-based simulations alone....
Abstract. Seasonal snow cover of the Northern Hemisphere (NH) is a major factor in global climate system, which makes an important variable models. Previously, substantial uncertainties have been reported NH water equivalent (SWE) estimates. A recent bias-correction method significantly reduces uncertainty SWE estimation, enables more reliable analysis models' ability to describe cover. We intercompared estimates between CMIP6 (Coupled Model Intercomparison Project Phase 6) models and...
Single scattering by randomly oriented Saharan sand, silt, and clay particles is studied at 441.6 nm wavelength. Numerical simulations using the ray optics approximation Lorenz‐Mie theory are compared with laboratory measurements of matrix elements reported in literature. The modified ad hoc simple schemes Lambertian surface internal screens to study effect small‐scale roughness structures, respectively. Two different reflection/refraction matrices varying depolarization characteristics...
Abstract. A climate-aerosol model is employed to study spatial and temporal variability of aerosol properties over India China for recent (year 2006) future conditions 2020) under different emission pathways. We present results mass concentration in size classes optical the five species treated by model. Aerosol depth have significant contributions from both anthropogenic natural aerosols. Different maxima regions, with highest concentrations found Kolkata elsewhere Ganges basin on northern...
Abstract. Snow consists of non-spherical grains various shapes and sizes. Still, in many radiative transfer applications, single-scattering properties snow have been based on the assumption spherical grains. More recently, second-generation Koch fractals employed. While they produce a relatively flat phase function typical deformed particles, this is still rather ad hoc choice. Here, angular scattering measurements for blowing conducted during CLimate IMpacts Short-Lived pollutants In Polar...
Abstract. Snow consists of non-spherical grains various shapes and sizes. Still, in radiative transfer calculations, snow are often treated as spherical. This also applies to the computation albedo Snow, Ice, Aerosol Radiation (SNICAR) model Los Alamos sea ice model, version 4 (CICE4), both which employed Community Earth System Model Norwegian (NorESM). In this study, we evaluate effect grain shape on climate simulated by NorESM a slab ocean configuration model. An experiment with spherical...
ABSTRACT The ongoing climate change alters the snow conditions. This paper evaluates these changes in Northern Europe including Fennoscandia and Baltic Sea region, based on data from newest generation of global models (Coupled Model Intercomparison Project phase 6; CMIP6). Thirteen CMIP6 are selected for analysis availability daily models' performance simulating European conditions Finland. focuses four quantities: largest value water equivalent during winter SWE max , length, start day end...
In order to effectively mitigate, adapt and benefit from climate change, society needs expertise. To enhance professional action competencies educate students in climate-informed decision making a new master-level course, "Living with changing climate" was developed. This course created by multidisciplinary team of experts the Institute for Atmospheric Earth System Research (UH-INAR), Finnish Meteorological (FMI) Department Educational Sciences at University Helsinki, as part...
Abstract. Climate models contain closure parameters to which the model climate is sensitive. These appear in physical parameterization schemes where some unresolved variables are expressed by predefined rather than being explicitly modeled. Currently, best expert knowledge used define optimal parameter values, based on observations, process studies, large eddy simulations, etc. Here, estimation, adaptive Markov chain Monte Carlo (MCMC) method, applied for estimation of joint posterior...
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