Aerosol direct radiative effects over the northwest Atlantic, northwest Pacific, and North Indian Oceans: estimates based on in-situ chemical and optical measurements and chemical transport modeling

International audienceThe largest uncertainty in the radiative forcing of climate change over the industrial era is that due to aerosols, a substantial fraction of which is the uncertainty associated with scattering and absorption of shortwave (solar) radiation by anthropogenic aerosols in cloud-free conditions (IPCC, 2001). Quantifying and reducing the uncertainty in aerosol influences on climate is critical to understanding climate change over the industrial period and to improving predictions of future climate change for assumed emission scenarios. Measurements of aerosol properties during major field campaigns in several regions of the globe during the past decade are contributing to an enhanced understanding of atmospheric aerosols and their effects on light scattering and climate. The present study, which focuses on three regions downwind of major urban/population centers (North Indian Ocean (NIO) during INDOEX, the Northwest Pacific Ocean (NWP) during ACE-Asia, and the Northwest Atlantic Ocean (NWA) during ICARTT), incorporates understanding gained from field observations of aerosol distributions and properties into calculations of perturbations in radiative fluxes due to these aerosols. This study evaluates the current state of observations and of two chemical transport models (STEM and MOZART). Measurements of burdens, extinction optical depth (AOD), and direct radiative effect of aerosols (DRE ? change in radiative flux due to total aerosols) are used as measurement-model check points to assess uncertainties. In-situ measured and remotely sensed aerosol properties for each region (mixing state, mass scattering efficiency, single scattering albedo, and angular scattering properties and their dependences on relative humidity) are used as input parameters to two radiative transfer models (GFDL and University of Michigan) to constrain estimates of aerosol radiative effects, with uncertainties in each step propagated through the analysis. Constraining the radiative transfer calculations by observational inputs increases the clear-sky, 24-h averaged AOD (34±8%), top of atmosphere (TOA) DRE (32±12%), and TOA direct climate forcing of aerosols (DCF ? change in radiative flux due to anthropogenic aerosols) (37±7%) relative to values obtained with "a priori" parameterizations of aerosol loadings and properties (GFDL RTM). The resulting constrained TOA DCF is ?3.3±0.47, ?14±2.6, ?6.4±2.1 Wm?2 for the NIO, NWP, and NWA, respectively. Constraining the radiative transfer calculations by observational inputs reduces the uncertainty range in the DCF in these regions relative to global IPCC (2001) estimates by a factor of approximately 2. Such comparisons with observations and resultant reductions in uncertainties are essential for improving and developing confidence in climate model calculations incorporating aerosol forcing

Temporal longitudinal associations of carotid-femoral pulse wave velocity and carotid intima-media thickness with resting heart rate and inflammation in youth.

This is the author accepted manuscriptData Availability Statement: The informed consent obtained from ALSPAC participants does not allow the data to be made freely available through any third party maintained public repository. However, data used for this submission can be made available on request to the ALSPAC Executive. The ALSPAC data management plan describes in detail the policy regarding data sharing, which is through a system of managed open access. Full instructions for applying for data access can be found here: http://www.bristol.ac.uk/alspac/researchers/access/. The ALSPAC study website contains details of all the data that are available (http://www.bristol.ac.uk/alspac/researchers/our-data/).We examined the temporal longitudinal associations of carotid-femoral pulse wave velocity (cfPWV) and carotid intima-media thickness (cIMT) with the risk of elevated resting heart rate (RHR) and high-sensitivity C-reactive protein (hsCRP). We studied 3862 adolescents, aged 17.7 years, followed-up for 7 years, from Avon Longitudinal Study of Parents and Children. RHR, fasting hsCRP, cfPWV and cIMT were repeatedly assessed and analysed using logistic regression, linear mixed-effect, and structural equation models. Among 3862 adolescents (2143 [55.5%] female), 10% and 44% were at moderate-to-high risk of elevated RHR and hsCRP at 24.5 years, respectively. Higher cfPWV at 17.7 years was associated with elevated RHR risk at follow-up [Odds-ratio (OR) 1.58 (CI 1.20-2.08); p=0.001] whilst cIMT at 17.7 years was associated with elevated hsCRP risk [OR 2.30 (1.18-4.46); p=0.014] at follow-up, only among females. In mixed-model, 7-year progression in cfPWV was directly associated with 7-year increase in RHR [effect-estimate 6 beats/min (1-11); p=0.017] and hsCRP. cIMT progression was associated with 7-year increase in RHR and hsCRP. In cross-lagged model, higher cfPWV at 17.7 years was associated with higher RHR [β = 0.06, standard-error = 3.85, p<0.0001] at 24.5 years but RHR at 17.7 years was unassociated with cfPWV at 24.5 years. Baseline cIMT or RHR was unassociated with either outcome at follow-up. Higher hsCRP at 17.7 years was associated with higher cfPWV and cIMT at 24.5 years. In conclusion, adolescent arterial stiffness but not cIMT appears to precede higher RHR in young adulthood, whilst elevated hsCRP in adolescence preceded higher cfPWV and cIMT.Medical Research CouncilWellcome TrustBritish Heart FoundationMedical Research CouncilJenny and Antti Wihuri FoundationNorth Savo regional and central Finnish Cultural FoundationNorth Savo regional and central Finnish Cultural FoundationYrjö Jahnsson FoundationFinnish Foundation for Cardiovascular ResearchOrion Research FoundationAarne Koskelo FoundationAntti and Tyyne Soininen FoundationPaulo FoundationPaavo Nurmi Foundatio