Evaluation of the statistical cloud scheme in the ECHAM5 model using satellite data

An evaluation of a statistical cloud scheme taking into account subgrid-scale variability for water vapour and cloud condensate in the ECHAM5 general circulation model of the atmosphere is presented. Three-dimensional modelled water vapour, cloud liquid water and cloud ice were distributed stochastically into subcolumns of each grid box and vertically integrated to total water path (TWP). Thus the lower atmosphere is emphasized in the evaluation of TWP due to its exponential profile. The edited model dataset was compared with the globally analyzed distribution of TWP measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument. The results show that the mean TWP and mean cloud cover are on average relatively well simulated. However, large deficiencies are revealed by the evaluation of both variance and skewness of the probability density function (PDF). Systematically negative deviations of variance are found for almost all regions of the globe. Skewness of theTWPis overestimated in the Tropics and underestimated at high latitudes. Moreover, sensitivity experiments were performed to reveal the deficiencies in the parametrization leading to the observed deviations of variance and skewness of TWP. It was found that the positive bias in skewness in the Tropics can be reduced by modifying the influence of convection on the PDF

Effects of snow grain shape on climate simulations : sensitivity tests with the Norwegian Earth System Model

Snow consists of non-spherical grains of various shapes and sizes. Still, in radiative transfer calculations, snow grains are often treated as spherical. This also applies to the computation of snow albedo in the Snow, Ice, and Aerosol Radiation (SNICAR) model and in the Los Alamos sea ice model, version 4 (CICE4), both of which are employed in the Community Earth System Model and in the Norwegian Earth System Model (NorESM). In this study, we evaluate the effect of snow grain shape on climate simulated by NorESM in a slab ocean configuration of the model. An experiment with spherical snow grains (SPH) is compared with another (NONSPH) in which the snow shortwave single-scattering properties are based on a combination of three non-spherical snow grain shapes optimized using measurements of angular scattering by blowing snow. The key difference between these treatments is that the asymmetry parameter is smaller in the non-spherical case (0.77-0.78 in the visible region) than in the spherical case (similar to 0.89). Therefore, for the same effective snow grain size (or equivalently, the same specific projected area), the snow broadband albedo is higher when assuming non-spherical rather than spherical snow grains, typically by 0.02-0.03. Considering the spherical case as the baseline, this results in an instantaneous negative change in net shortwave radiation with a global-mean top-of-the-model value of ca. -0.22Wm(-2). Although this global-mean radiative effect is rather modest, the impacts on the climate simulated by NorESM are substantial. The global annual-mean 2m air temperature in NONSPH is 1.17K lower than in SPH, with substantially larger differences at high latitudes. The climatic response is amplified by strong snow and sea ice feedbacks. It is further demonstrated that the effect of snow grain shape could be largely offset by adjusting the snow grain size. When assuming non-spherical snow grains with the parameterized grain size increased by ca. 70 %, the climatic differences to the SPH experiment become very small. Finally, the impact of assumed snow grain shape on the radiative effects of absorbing aerosols in snow is discussed.Peer reviewe

Crack avalanches in the three dimensional random fuse model

We analyze the scaling of avalanche precursors in the three dimensional random fuse model by numerical simulations. We find that both the integrated and non-integrated avalanche size distributions are in good agreement with the results of the global load sharing fiber bundle model, which represents the mean-field limit of the model.Comment: 6 pages, 2 figures, submitted for the proceedings of the conference "Physics Survey of Irregular Systems", in honor of Bernard Sapova

The HIRLAM fast radiation scheme for mesoscale numerical weather prediction models

This paper provides an overview of the HLRADIA shortwave (SW) and longwave (LW) broadband radiation schemes used in the HIRLAM numerical weather prediction (NWP) model and available in the HARMONIE-AROME mesoscale NWP model. The advantage of broadband, over spectral, schemes is that they can be called more frequently within the model, without compromising on computational efficiency. In mesoscale models fast interactions between clouds and radiation and the surface and radiation can be of greater importance than accounting for the spectral details of clear-sky radiation; thus calling the routines more frequently can be of greater benefit than the deterioration due to loss of spectral details. Fast but physically based radiation parametrizations are expected to be valuable for high-resolution ensemble forecasting, because as well as the speed of their execution, they may provide realistic physical perturbations. Results from single-column diagnostic experiments based on CIRC benchmark cases and an evaluation of 10 years of radiation output from the FMI operational archive of HIRLAM forecasts indicate that HLRADIA performs sufficiently well with respect to the clear-sky downwelling SW and longwave LWfluxes at the surface. In general, HLRADIA tends to overestimate surface fluxes, with the exception of LW fluxes under cold and dry conditions. The most obvious overestimation of the surface SW flux was seen in the cloudy cases in the 10-year comparison; this bias may be related to using a cloud inhomogeneity correction, which was too large. According to the CIRC comparisons, the outgoing LW and SW fluxes at the top of atmosphere are mostly overestimated by HLRADIA and the net LW flux is underestimated above clouds. The absorption of SW radiation by the atmosphere seems to be underestimated and LW absorption seems to be overestimated. Despite these issues, the overall results are satisfying and work on the improvement of HLRADIA for the use in HARMONIE-AROME NWP system is ongoing. In a HARMONIE-AROME 3-D forecast experiment we have shown that the frequency of the call for the radiation parametrization and choice of the parametrization scheme makes a difference to the surface radiation fluxes and changes the spatial distribution of the vertically integrated cloud cover and precipitation.Peer reviewe

High but stable incidence of adult-onset asthma in northern Sweden over the last decades

Background The prevalence of asthma has increased both among children and adults during the latter half of the 20th century. The prevalence among adults is affected by the incidence of asthma not only in childhood but also in adulthood. Time trends in asthma incidence have been poorly studied. Aims The aim of this study was to review the incidence of adult-onset asthma from 1996 to 2006 and 2006 to 2016 and compare the risk factor patterns. Methods In the Obstructive Lung Disease in Northern Sweden (OLIN) studies, two randomly selected population-based samples in the 20-69-year age group participated in postal questionnaire surveys about asthma in 1996 (n=7104, 85%) and 2006 (n=6165, 77%). A 10-year follow-up of the two cohorts with the same validated questionnaire was performed, and 5709 and 4552 responded, respectively. Different definitions of population at risk were used in the calculations of asthma incidence. The protocol followed a study performed between 1986 and 1996 in the same area. Results The crude incidence rate of physician-diagnosed asthma was 4.4 per 1000 person-years (men 3.8, women 5.5) from 1996 to 2006, and 4.8 per 1000 person-years (men 3.7, women 6.2) from 2006 to 2016. When correcting for possible under-diagnosis at study entry, the incidence rate was 2.4 per 1000 personyears from 1996 to 2006 and 2.6 per 1000 person-years from 2006 to 2016. The incidence rates were similar across age groups. Allergic rhino-conjunctivitis was the main risk factor for incident asthma in both observation periods (risk ratio 2.4-2.6). Conclusions The incidence of adult-onset asthma has been stable over the last two decades and has remained at a similar level since the 1980s. The high incidence contributes to the increase in asthma prevalence.Peer reviewe

Role of climate model dynamics in estimated climate responses to anthropogenic aerosols

Peer reviewe

Aerosol optical depth comparison between GAW-PFR and AERONET-Cimel radiometers from long-term (2005–2015) 1 min synchronous measurements

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 radiometers (AERONET-Cimel), calibrated individually with the Langley plot technique, was performed for four common or “near” wavelengths, 380, 440, 500 and 870 nm, in the period 2005–2015. The goal of this study is to assess whether, despite the marked technical differences between both networks (AERONET, GAW-PFR) and the number of instruments used, their long-term AOD data are comparable and consistent. The percentage of data meeting the World Meteorological Organization (WMO) traceability requirements (95 % of the AOD differences of an instrument compared to the WMO standards lie within specific limits) is >92 % at 380 nm, >95 % at 440 nm and 500 nm, and 98 % at 870 nm, with the results being quite similar for both AERONET version 2 (V2) and version 3 (V3). For the data outside these limits, the contribution of calibration and differences in the calculation of the optical depth contribution due to Rayleigh scattering and O3 and NO2absorption have a negligible impact. For AOD >0.1, a small but non-negligible percentage (∼1.9 %) of the AOD data outside the WMO limits at 380 nm can be partly assigned to the impact of dust aerosol forward scattering on the AOD calculation due to the different field of view of the instruments. Due to this effect the GAW-PFR provides AOD values, which are ∼3 % lower at 380 nm and ∼2 % lower at 500 nm compared with AERONET-Cimel. The comparison of the Ångström exponent (AE) shows that under non-pristine conditions (AOD >0.03 and AE <1) the AE differences remain <0.1. This long-term comparison shows an excellent traceability of AERONET-Cimel AOD with the World AOD reference at 440, 500 and 870 nm channels and a fairly good agreement at 380 nm, although AOD should be improved in the UV range.The Federal Office of Meteorology and Climatology MeteoSwiss International Affairs Division, Swiss GCOS Office, has funded the project “The Global Atmosphere Watch Precision Filter Radiometer (GAW-PFR) Network for Aerosol Optical Depth long term measurements”, and specifically the GAW-PFR program at the Izaña Observatory. AEMET has funded the AERONET programme at the Izaña Observatory. Some of the AERONET-Cimel radiometers have been calibrated at Izaña Observatory by the AERONET Europe Calibration Service, financed by specific European Community programmes for integrating activities: Research Infrastructure Action under the Seventh Framework Programme (grant no. FP7/2007-2013) and ACTRIS (grant no. 45 262254). This research has received funding from the European Union's Horizon 2020 Research and Innovation Programme (grant no. 654109) (ACTRIS-2). Funding from MINECO (grant no. CTM2015-66742-R) and Junta de Castilla y León (grant no. VA100P17) is also gratefully acknowledged. Much of this study has been performed in the frame of the WMO CIMO Izaña test bed for aerosols and water vapour remote-sensing instruments funded by AEMET

Aerosol Optical Depth comparison between GAW-PFR and AERONET-Cimel radiometers from long term (2005–2015) 1-minute synchronous measurements [Discussion paper]

A comprehensive comparison of more than 70000 synchronous 1-minute aerosol optical depth (AOD) data from three Global Atmosphere Watch-Precision Filter Radiometer (GAW-PFR) and 15 Aerosol Robotic Network-Cimel (AERONET-Cimel) radiometers was performed for the four nearby wavelengths (380, 440, 500 and 870nm) in the period 2005–2015. The goal of this study is to assess whether, despite the marked differences between both networks and the number of instruments used, their long term AOD data are comparable and consistent. AOD traceability established by the World Meteorological Organization (WMO) consists in determining the percentage of synchronous data within specific limits. If, at least, 95% of the AOD differences of an instrument compared to the WMO standards lie within these limits, both data populations are considered equivalent. The percentage of traceable data is 92.7% (380nm), 95.7% (440nm), 95.8% (500nm) and 98.0% (870nm). When small misalignments in GAW-PFR sun-pointing were fixed (period 2010–2015), the percentage of traceable data increased. The contribution of calibration related aspects to comparison outside the 95% traceability limits is insignificant in all channels, except in 380nm. The simultaneous failure of both cloud screening algorithms might occur only under the presence of cirrus, or altostratus clouds on the top of a dust-laden Saharan air layer. Differences in the calculation of the optical depth contribution due to Rayleigh scattering, and O3 and NO2 absorption have a negligible impact. For AOD >0.1, a non-negligible percentage (≈1.9%) of the AOD data outside the 95% traceability limits at 380nm can be partly assigned to the different field of view of the instruments. The comparison of the Angström exponent (AE) shows that under non-pristine conditions (AOD >0.03 and AE <1) the AE differences remain <0.1. The excellent traceability in this study has been obtained using well calibrated Master instruments.The work was supported by the project “The Global Atmosphere Watch Precision Filter Radiometer (GAW-PFR) Network for Aerosol Optical Depth long term measurements” supported by Bundesamt für Meteorologie und Klimatologie MeteoSchweiz – GCOS Swiss Office. Part of the AERONET-Cimel radiometers have been calibrated at Izaña Observatory by AERONETEUROPE Calibration Service, financed by the European Community specific programs for Integrating Activities: Research Infrastructure Action under the Seventh Framework Programme (FP7/2007-2013), ACTRIS grant agreement No. 262254, and Horizon 2020 Research 25 and Innovation Program, ACTRIS-2 grant agreement No. 654109. This research has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 654109 (ACTRIS-2).The funding by MINECO (CTM2015-66742-R) and Junta de Castilla y León (VA100P17) is also gratefully acknowledge

Nudging service providers and assessing service trade-offs to reduce the social inefficiencies of payments for ecosystem services schemes

Socially inefficient payment for ecosystem services (PES) schemes result when adverse shifts in the provisioning of other ecosystem services (ES) or overpayment to service providers occur. To address these inefficiencies, a holistic evaluation of trade-offs between services should be conducted in parallel with determining land owners' service provisioning preferences. Recent evidence also suggests that nudging stakeholders' preferences could be a useful policy design tool to address global change challenges. Forest owners' landscape management preferences were nudged to determine the impact on the social efficiency of PES schemes for biodiversity conservation and climate change mitigation in Finland. ES indicators for biodiversity conservation, carbon storage, and the albedo effect were included with traditional provisioning services (i.e. timber) and bioenergy to assess the consequent intra-service trade-offs. Synergies in provisioning of regulating services were identified, but were found to be more efficient when the management objective is for biodiversity conservation rather than climate change regulation. Nudging led to marginal gains in service provisioning above the baseline management and above neutral owner preferences, and increased aggregate service provisioning. This demonstrates the importance of considering intra-service trade-offs and that nudging could be an important tool for designing efficient PES schemes. (C) 2015 Elsevier Ltd. All rights reserved.Peer reviewe