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| 2. |
- Bender, Frida A.-M., et al.
(författare)
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Assessment of aerosol-cloud-radiation correlations in satellite observations, climate models and reanalysis
- 2019
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Ingår i: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 52:7-8, s. 4371-4392
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Tidskriftsartikel (refereegranskat)abstract
- Representing large-scale co-variability between variables related to aerosols, clouds and radiation is one of many aspects of agreement with observations desirable for a climate model. In this study such relations are investigated in terms of temporal correlations on monthly mean scale, to identify points of agreement and disagreement with observations. Ten regions with different meteorological characteristics and aerosol signatures are studied and correlation matrices for the selected regions offer an overview of model ability to represent present day climate variability. Global climate models with different levels of detail and sophistication in their representation of aerosols and clouds are compared with satellite observations and reanalysis assimilating meteorological fields as well as aerosol optical depth from observations. One example of how the correlation comparison can guide model evaluation and development is the often studied relation between cloud droplet number and water content. Reanalysis, with no parameterized aerosol–cloud coupling, shows weaker correlations than observations, indicating that microphysical couplings between cloud droplet number and water content are not negligible for the co-variations emerging on larger scale. These observed correlations are, however, not in agreement with those expected from dominance of the underlying microphysical aerosol–cloud couplings. For instance, negative correlations in subtropical stratocumulus regions show that suppression of precipitation and subsequent increase in water content due to aerosol is not a dominating process on this scale. Only in one of the studied models are cloud dynamics able to overcome the parameterized dependence of rain formation on droplet number concentration, and negative correlations in the stratocumulus regions are reproduced.
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| 3. |
- Esgard, Veronica Frey, et al.
(författare)
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Diagnostic methods and written advice for acute otitis media in primary health care
- 2024
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Ingår i: Scandinavian Journal of Primary Health Care. - : TAYLOR & FRANCIS LTD. - 0281-3432 .- 1502-7724.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Otomicroscopy and pneumatic methods are superior to otoscopy alone in diagnosing acute otitis media (AOM). There is a lack of knowledge regarding the use of different diagnostic methods for AOM in primary health care in Sweden and Norway. Methods: This cross-sectional study included a questionnaire completed by general practitioners (GPs) and specialist trainees (STs/residents/registrars) working in primary care in Sweden and Norway. Multivariable binary logistic regressions were performed to evaluate the use of diagnostic methods and written advice adjusted for educational level, sex and country. Results: Otoscopy was the most frequently used method. Sweden had greater access to the more accurate diagnostic methods. In Norway, the following methods were used to a lesser extent: pneumatic otoscopy, adjusted OR 0.15 (95% CI 0.10-0.23; p < .001), otomicroscopy, adjusted OR 0.013 (95% CI 0.070-0.027; p < .001), pneumatic otomicroscopy, adjusted OR 0.028 (95% CI 0.010-0.078; p < .001) and tympanometry, adjusted OR 0.31 (95% CI 0.21-0.45; p < .001). Written advice was used to a greater extent in Norway, adjusted OR 4.5 (95% CI 3.1-6.7; p < .001). The STs used pneumatic otoscopy and pneumatic otomicroscopy to a lesser extent, adjusted OR 0.65 (95% CI 0.45-0.93; p = .019) and 0.63 (95% CI 0.43-0.92; p = .016). Conclusions: Swedish physicians both used and had greater access to the significantly better diagnostic methods compared with Norwegian physicians while the opposite applied to the use of written information. The GPs used pneumatic otoscopy and pneumatic otomicroscopy to a greater extent than STs. Compared with 2012, the Swedish physicians now more frequently used pneumatic otoscopy.
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| 4. |
- Frey Esgård, Veronica, et al.
(författare)
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Diagnostic methods and written advice for acute otitis media in primary health care
- 2024
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Ingår i: Scandinavian Journal of Primary Health Care. - : Taylor & Francis. - 0281-3432 .- 1502-7724.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Otomicroscopy and pneumatic methods are superior to otoscopy alone in diagnosing acute otitis media (AOM). There is a lack of knowledge regarding the use of different diagnostic methods for AOM in primary health care in Sweden and Norway.Methods: This cross-sectional study included a questionnaire completed by general practitioners (GPs) and specialist trainees (STs/residents/registrars) working in primary care in Sweden and Norway. Multivariable binary logistic regressions were performed to evaluate the use of diagnostic methods and written advice adjusted for educational level, sex and country.Results: Otoscopy was the most frequently used method. Sweden had greater access to the more accurate diagnostic methods. In Norway, the following methods were used to a lesser extent: pneumatic otoscopy, adjusted OR 0.15 (95% CI 0.10–0.23; p < .001), otomicroscopy, adjusted OR 0.013 (95% CI 0.070–0.027; p < .001), pneumatic otomicroscopy, adjusted OR 0.028 (95% CI 0.010–0.078; p < .001) and tympanometry, adjusted OR 0.31 (95% CI 0.21–0.45; p < .001). Written advice was used to a greater extent in Norway, adjusted OR 4.5 (95% CI 3.1–6.7; p < .001). The STs used pneumatic otoscopy and pneumatic otomicroscopy to a lesser extent, adjusted OR 0.65 (95% CI 0.45–0.93; p = .019) and 0.63 (95% CI 0.43–0.92; p = .016).Conclusions: Swedish physicians both used and had greater access to the significantly better diagnostic methods compared with Norwegian physicians while the opposite applied to the use of written information. The GPs used pneumatic otoscopy and pneumatic otomicroscopy to a greater extent than STs. Compared with 2012, the Swedish physicians now more frequently used pneumatic otoscopy.
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| 5. |
- Frey, Lena, et al.
(författare)
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Absorbing aerosols over Asia – an inter-model and model-observation comparison study using CAM5.3-Oslo
- 2021
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Ingår i: Tellus. Series B, Chemical and physical meteorology. - : Stockholm University Press. - 0280-6509 .- 1600-0889. ; 73:1, s. 1-25
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol absorption constitutes a significant component of the total radiative effect of aerosols, and hence its representation in general circulation models is crucial to radiative forcing estimates. We use here multiple observations to evaluate the performance of CAM5.3-Oslo with respect to its aerosol representation. CAM5.3-Oslo is the atmospheric component of the earth system model NorESM1.2 and shows on average an underestimation of aerosol absorption in the focus region over East and South Asia and a strong aerosol absorption overestimation in desert and arid regions compared to observations and other AeroCom phase III models. We explore the reasons of the model spread and find that it is related to the column burden and residence time of absorbing aerosols, in particular black carbon and dust. We conduct further sensitivity simulations with CAM5.3-Oslo to identify processes which are most important for modelled aerosol absorption. The sensitivity experiments target aerosol optical properties, and contrast their impact with effects from changes in emissions and deposition processes, and the driving meteorology. An improved agreement with observations was found with the use of a refined emission data set, transient emissions and assimilation of meteorological observations. Changes in optical properties of absorbing aerosols can also reduce the under- and overestimation of aerosol absorption in the model. However, changes in aerosol absorption strength between the sensitivity experiments are small compared to the inter-model spread among the AeroCom phase III models.
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| 6. |
- Frey, Lena, 1986-
(författare)
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Aerosol-cloud-radiation interactions in global climate models
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Clouds can reflect, absorb and re-emit radiation, thereby inducing a cooling or warming effect on the climate. However, the response of clouds to a changing climate is highly uncertain and the representation of clouds in state-of-the-art climate models remains a key challenge for future climate projections. Factors contributing to this uncertainty include processes on the microphysical scale involving aerosol particles with the size of just a few nanometers to micrometers. This thesis focuses on the representation of aerosol-cloud-radiation interactions in global climate models. Using idealized experiments from a model-intercomparison project with different anthropogenic aerosol forcings, it was found that both sulfate and non-sulfate aerosols yield an increase in cloud albedo in five regions of subtropical marine stratocumulus clouds. The changes in cloud albedo in the models were driven by changes in the cloud droplet number concentration and liquid water content. Further, it was found that the microphysical coupling of underlying aerosol-cloud interactions in models seems to dominate on the monthly timescale in subtropical marine stratocumulus regions, which can not be confirmed in observations. Quantifying the effect of aerosols on cloud properties in observations remains challenging. In addition, comparisons with satellite retrievals and the global climate model NorESM showed that this model is not able to capture elevated aerosol above cloud, seen in observations in two regions of marine stratocumulus clouds. Sensitivity experiments revealed that the model is most sensitive to the aerosol emissions, convection and wet scavenging in terms of the vertical aerosol distribution. Finally, the representation of aerosol absorption in global climate models was investigated. It was found that most of the models underestimate absorption by aerosols in a focus domain in Asia. Sensitivity studies with NorESM give rise to variations that lie within the large inter-model diversity.
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| 7. |
- Frey, Lena, et al.
(författare)
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Cloud albedo changes in response to anthropogenic sulfate and non-sulfate forcings in CMIP5 models
- 2017
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 17:14, s. 9145-9162
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Tidskriftsartikel (refereegranskat)abstract
- The effects of different aerosol types on cloud albedo are analysed using the linear relation between total albedo and cloud fraction found on a monthly mean scale in regions of subtropical marine stratocumulus clouds and the influence of simulated aerosol variations on this relation. Model experiments from the Coupled Model Intercomparison Project phase 5 (CMIP5) are used to separately study the responses to increases in sulfate, non-sulfate and all anthropogenic aerosols. A cloud brightening on the month-to-month scale due to variability in the background aerosol is found to dominate even in the cases where anthropogenic aerosols are added. The aerosol composition is of importance for this cloud brightening, that is thereby region dependent. There is indication that absorbing aerosols to some extent counteract the cloud brightening but scene darkening with increasing aerosol burden is generally not supported, even in regions where absorbing aerosols dominate. Month-to-month cloud albedo variability also confirms the importance of liquid water content for cloud albedo. Regional, monthly mean cloud albedo is found to increase with the addition of anthropogenic aerosols and more so with sulfate than non-sulfate. Changes in cloud albedo between experiments are related to changes in cloud water content as well as droplet size distribution changes, so that models with large increases in liquid water path and/or cloud droplet number show large cloud albedo increases with increasing aerosol. However, no clear relation between model sensitivities to aerosol variations on the month-to-month scale and changes in cloud albedo due to changed aerosol burden is found.
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| 8. |
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| 9. |
- Frey, Lena, et al.
(författare)
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Processes controlling the vertical aerosol distribution in marine stratocumulus regions - a sensitivity study using the climate model NorESM1-M
- 2021
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 21:1, s. 577-595
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Tidskriftsartikel (refereegranskat)abstract
- The vertical distribution of aerosols plays an important role in determining the effective radiative forcing from aerosol–radiation and aerosol–cloud interactions. Here, a number of processes controlling the vertical distribution of aerosol in five subtropical marine stratocumulus regions in the climate model NorESM1-M are investigated, with a focus on the total aerosol extinction. A comparison with satellite lidar data (CALIOP, Cloud–Aerosol Lidar with Orthogonal Polarization) shows that the model underestimates aerosol extinction throughout the troposphere, especially elevated aerosol layers in the two regions where they are seen in observations. It is found that the shape of the vertical aerosol distribution is largely determined by the aerosol emission and removal processes in the model, primarily through the injection height, emitted particle size, and wet scavenging. In addition, the representation of vertical transport related to shallow convection and entrainment is found to be important, whereas alterations in aerosol optical properties and cloud microphysics parameterizations have smaller effects on the vertical aerosol extinction distribution. However, none of the alterations made are sufficient for reproducing the observed vertical distribution of aerosol extinction, neither in magnitude nor in shape. Interpolating the vertical levels of CALIOP to the corresponding model levels leads to better agreement in the boundary layer and highlights the importance of the vertical resolution.
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| 10. |
- Jung, Christian, et al.
(författare)
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A comparison of very old patients admitted to intensive care unit after acute versus elective surgery or intervention
- 2019
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Ingår i: Journal of critical care. - : W B SAUNDERS CO-ELSEVIER INC. - 0883-9441 .- 1557-8615. ; 52, s. 141-148
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Tidskriftsartikel (refereegranskat)abstract
- Background: We aimed to evaluate differences in outcome between patients admitted to intensive care unit (ICU) after elective versus acute surgery in a multinational cohort of very old patients (80 years; VIP). Predictors of mortality, with special emphasis on frailty, were assessed.Methods: In total, 5063 VIPs were induded in this analysis, 922 were admitted after elective surgery or intervention, 4141 acutely, with 402 after acute surgery. Differences were calculated using Mann-Whitney-U test and Wilcoxon test. Univariate and multivariable logistic regression were used to assess associations with mortality.Results: Compared patients admitted after acute surgery, patients admitted after elective surgery suffered less often from frailty as defined as CFS (28% vs 46%; p < 0.001), evidenced lower SOFA scores (4 +/- 5 vs 7 +/- 7; p < 0.001). Presence of frailty (CFS >4) was associated with significantly increased mortality both in elective surgery patients (7% vs 12%; p = 0.01), in acute surgery (7% vs 12%; p = 0.02).Conclusions: VIPs admitted to ICU after elective surgery evidenced favorable outcome over patients after acute surgery even after correction for relevant confounders. Frailty might be used to guide clinicians in risk stratification in both patients admitted after elective and acute surgery.
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