The Whole Atmosphere Community Climate Model Version 6 (WACCM6)

The Whole Atmosphere Community Climate Model version 6 (WACCM6) is a major update of the whole atmosphere modeling capability in the Community Earth System Model (CESM), featuring enhanced physical, chemical and aerosol parameterizations. This work describes WACCM6 and some of the important features of the model. WACCM6 can reproduce many modes of variability and trends in the middle atmosphere, including the Quasi‐Biennial Oscillation, Stratospheric Sudden Warmings and the evolution of Southern Hemisphere springtime ozone depletion over the 20th century. WACCM6 can also reproduce the climate and temperature trends of the 20th century throughout the atmospheric column. The representation of the climate has improved in WACCM6, relative to WACCM4. In addition, there are improvements in high latitude climate variability at the surface and sea ice extent in WACCM6 over the lower top version of the model (CAM6) that come from the extended vertical domain and expanded aerosol chemistry in WACCM6, highlighting the importance of the stratosphere and tropospheric chemistry for high latitude climate variability

HCV reinfection after HCV therapy among HIV/HCV-coinfected individuals in Europe

OBJECTIVES: Although direct-acting antivirals (DAAs) can clear HCV in nearly all HIV/HCV-coinfected individuals, high rates of reinfection may hamper efforts to eliminate HCV in this population. We investigated reinfection after sustained virological response (SVR) in HIV/HCV-coinfected individuals in Europe. METHODS: Factors associated with odds of reinfection by 2 years after SVR in EuroSIDA participants with one or more HCV-RNA test and 2 years follow-up were assessed using logistic regression. RESULTS: Overall, 1022 individuals were included. The median age was 50 (interquartile range: 43–54 years), and most were male (78%), injection drug users (52%), and received interferon (IFN)-free DAAs (62%). By 24 months, 75 [7.3%, 95% confidence interval (CI): 5.7–8.9%] individuals were reinfected. Among individuals treated prior to 2014, 16.1% were reinfected compared with 4.2% and 8.3%, respectively, among those treated during or after 2014 with IFN-free and IFN-based therapy. After adjustment, individuals who had started treatment during or after 2014 with IFN-free or IFN-based therapy had significantly lower odds of reinfection (adjusted odds ratio = 0.21, 95% CI: 0.11–0.38; 0.43, 95% CI: 0.22–0.83) compared with those who had received therapy before 2014. There were no significant differences in odds of reinfection according to age, gender, European region, HIV transmission risk group or liver fibrosis. CONCLUSIONS: Among HIV/HCV-coinfected individuals in Europe, 7.3% were reinfected with HCV within 24 months of achieving SVR, with evidence suggesting that this is decreasing over time and with use of newer HCV regimens. Harm reduction to reduce reinfection and surveillance to detect early reinfection with an offer of treatment are essential to eliminate HCV

Dynamical processes in the Arctic atmosphere

This book presents current knowledge on chemistry and physics of Arctic atmosphere. Special attention is given to studies of the Arctic haze phenomenon, Arctic tropospheric clouds, Arctic fog, polar stratospheric and mesospheric clouds, atmospheric dynamics, thermodynamics and radiative transfer as related to the polar environment. The atmosphere-cryosphere feedbacks and atmospheric remote sensing techniques are presented in detail. The problems of climate change in the Arctic are also addressed