1,136 research outputs found

    Developing a monthly radiative kernel for surface albedo change from satellite climatologies of Earth\u27s shortwave radiation budget: CACK v1.0

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    Due to the potential for land-useā€“land-cover change (LULCC) to alter surface albedo, there is need within the LULCC science community for simple and transparent tools for predicting radiative forcings (Ī”F) from surface albedo changes (Ī”Ī±s). To that end, the radiative kernel technique ā€“ developed by the climate modeling community to diagnose internal feedbacks within general circulation models (GCMs) ā€“ has been adopted by the LULCC science community as a tool to perform offline Ī”F calculations for Ī”Ī±s. However, the codes and data behind the GCM kernels are not readily transparent, and the climatologies of the atmospheric state variables used to derive them vary widely both in time period and duration. Observation-based kernels offer an attractive alternative to GCM-based kernels and could be updated annually at relatively low costs. Here, we present a radiative kernel for surface albedo change founded on a novel, simplified parameterization of shortwave radiative transfer driven with inputs from the Clouds and the Earth\u27s Radiant Energy System (CERES) Energy Balance and Filled (EBAF) products. When constructed on a 16-year climatology (2001ā€“2016), we find that the CERES-based albedo change kernel ā€“ or CACK ā€“ agrees remarkably well with the mean kernel of four GCMs (rRMSEā€‰=ā€‰14ā€‰%). When the novel parameterization underlying CACK is applied to emulate two of the GCM kernels using their own boundary fluxes as input, we find even greater agreement (mean rRMSEā€‰=ā€‰7.4ā€‰%), suggesting that this simple and transparent parameterization represents a credible candidate for a satellite-based alternative to GCM kernels. We document and compute the various sources of uncertainty underlying CACK and include them as part of a more extensive dataset (CACK v1.0) while providing examples showcasing its application

    Simple Models Outperform More Complex Big-Leaf Models of Daily Transpiration in Forested Biomes

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    Transpiration makes up the bulk of total evaporation in forested environments yet remains challenging to predict at landscape-to-global scales. We harnessed independent estimates of daily transpiration derived from co-located sap flow and eddy-covariance measurement systems and applied the triple collocation technique to evaluate predictions from big leaf models requiring no calibration. In total, four models in 608 unique configurations were evaluated at 21 forested sites spanning a wide diversity of biophysical attributes and environmental backgrounds. We found that simpler models that neither explicitly represented aerodynamic forcing nor canopy conductance achieved higher accuracy and signal-to-noise levels when optimally configured (rRMSE = 20%; R2 = 0.89). Irrespective of model type, optimal configurations were those making use of key plant functional type dependent parameters, daily LAI, and constraints based on atmospheric moisture demand over soil moisture supply. Our findings have implications for more informed water resource management based on hydrological modeling and remote sensing.publishedVersio

    Climate change mitigation potential of biochar from forestry residues under boreal condition

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    Forest harvest residue is a low-competitive biomass feedstock that is usually left to decay on site after forestry operations. Its removal and pyrolytic conversion to biochar is seen as an opportunity to reduce terrestrial CO2 emissions and mitigate climate change. The mitigation effect of biochar is, however, ultimately dependent on the availability of the biomass feedstock, thus CO2 removal of biochar needs to be assessed in relation to the capacity to supply biochar systems with biomass feedstocks over prolonged time scales, relevant for climate mitigation. In the present study we used an assembly of empirical models to forecast the effects of harvest residue removal on soil C storage and the technical capacity of biochar to mitigate national-scale emissions over the century, using Norway as a case study for boreal conditions. We estimate the mitigation potential to vary between 0.41 and 0.78 Tg CO2 equivalents yrāˆ’1, of which 79% could be attributed to increased soil C stock, and 21% to the coproduction of bioenergy. These values correspond to 9ā€“17% of the emissions of the Norwegian agricultural sector and to 0.8ā€“1.5% of the total national emission. This illustrates that deployment of biochar from forest harvest residues in countries with a large forestry sector, relative to economy and population size, is likely to have a relatively small contribution to national emission reduction targets but may have a large effect on agricultural emission and commitments. Strategies for biochar deployment need to consider that biochar's mitigation effect is limited by the feedstock supply which needs to be critically assessed.acceptedVersio

    Exogenous sex steroid hormones and asthma in females:protocol for a population-based retrospective cohort study using a UK primary care database

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    This work was supported by Asthma UK, grant number: AUK-IG-2016-346. BIN, INS, CRS and AS were in addition support by the Farr Institute and Asthma UK Centre for Applied Research. BIN acknowledges the support of Knut and Alice Wallenberg Foundation and the Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Sweden.Peer reviewedPublisher PD

    Hormone replacement therapy and asthma onset in menopausal women: National cohort study

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    Ā© 2020 The Authors Background: There is uncertainty about the role of hormonal replacement therapy (HRT) in the development of asthma. Objective: We investigated whether use of HRT and duration of use was associated with risk of development of asthma in perimenopausal and postmenopausal women. Methods: We constructed a 17-year (from January 1, 2000, to December 31, 2016) open cohort of 353,173 women (aged 46-70 years) from the Optimum Patient Care Database, a longitudinal primary care database from across the United Kingdom. HRT use, subtypes, and duration of use; confounding variables; and asthma onset were defined by using the Read Clinical Classification System. We fitted multilevel Cox regression models to estimate hazard ratios (HRs) with 95% CIs. Results: During the 17-year follow-up (1,340,423 person years), 7,614 new asthma cases occurred, giving an incidence rate of 5.7 (95% CI = 5.5-5.8) per 1,000 person years. Compared with nonuse of HRT, previous use of any (HR = 0.83; 95% CI = 0.76-0.88), estrogen-only (HR = 0.89; 95% CI = 0.84-0.95), or combined estrogen and progestogen (HR = 0.82; 95% CI = 0.76-0.88) HRT was associated with a reduced risk of asthma onset. This was also the case with current use of any (HR = 0.79; 95% CI = 0.74-0.85), estrogen-only (HR = 0.80; 95% CI = 0.73-0.87), and combined estrogen and progestogen (HR = 0.78; 95% CI = 0.70-0.87) HRT. Longer duration of HRT use (1-2 years [HR = 0.93; 95% CI = 0.87-0.99]; 3-4 years [HR = 0.77; 95% CI = 0.70-0.84]; and ā‰„5 years [HR = 0.71; 95% CI = 0.64-0.78]) was associated with a dose-response reduced risk of asthma onset.Conclusion: We found that HRT was associated with a reduced risk of development of late onset asthma in menopausal women. Further cohort studies are needed to confirm these findings

    Hormone Replacement Therapy and Risk of Severe Asthma Exacerbation in Perimenopausal and Postmenopausal Women : 17-Year National Cohort Study

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    This work was supported by Asthma UK, grant number: AUK-IG-2016-346 and Health Data Research UK. We thank Optimum Patient Care (OPC) and Observational and Pragmatic Research Institute Pte Ltd (OPRI) for making the OPCRD database (www.opcrd.co.uk) available free of charge. B. I. Nwaru acknowledges the support of Knut and Alice Wallenberg Foundation, the Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Sweden, and the VBG Group Herman Krefting Foundation on Asthma and Allergy. A. Sheikh acknowledges support of Health Data Research UK (BREATHE).Peer reviewedPublisher PD
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