Structure of the Atlantic Meridional Overturning Circulation in Three Generations of Climate Models

Abstract Through a large meridional transport of heat and freshwater, the Atlantic meridional overturning circulation (AMOC) plays a fundamental role in the earth climate system. Yet, there exist significant biases in representing AMOC structures in climate models and it is unclear whether or to what extent the biases have reduced through different generations of climate models. To address this question, this study compared the AMOC represented in three phases of the Coupled Model Intercomparison Project (CMIP) models with a similar horizontal resolution: CMIP3, CMIP5, and CMIP6. We found that (a) although the model spread is large, the multi‐model ensemble of each CMIP reproduced a similar AMOC magnitude and the overturning depth that are in a reasonable agreement with observations; (b) in each CMIP, there is a smaller temperature and salinity difference between the northward flowing top limb and the southward flowing second limb of the AMOC, which lead to a systematic bias of a weaker meridional transport of heat and freshwater; (c) these biases are generally similar in CMIP5 and CMIP6 and significantly improved from CMIP3

Hazard Assessments of Riverbank Flooding and Backward Flows in Dike-Through Drainage Ditches during Moderate Frequent Flooding Events in the Ningxia Reach of the Upper Yellow River (NRYR)

In this study, the riverbank inundation caused by moderate frequent flooding events (with recurrence periods of less than 20 years), along with the increasingly serious hazards of backward flows in dike-through drainage ditches in the Ningxia Reach of the upper Yellow River (NRYR), were investigated. Then, a comprehensive method for hazard assessment of the floodplains and backward flows in the NRYR was proposed, which fully integrated geographical information systems (GISs), remote sensing (RS), and a digital elevation model (DEM), as well as river dynamics theory. This study first established a one-dimensional unsteady hydrodynamic model for the NRYR. The historical flood hydrology observation from 2012, along with the aerial image measurement data of the study area, were used to calibrate and verify the accuracy of the model. The hazards of riverbank inundation and damages to water affected engineering facilities, as well as the backward flows of dike-through drainage ditches caused by the moderate frequent flooding events, were comprehensively analyzed. Also, this study configured the hazard map and proposed revisions to the flood hazard ranking regime definitions, and discussed the impacts and prevention and control measures of moderate frequent flood damages. The proposed method could effectively meet the hazard analysis demands of the moderate frequent flooding events in the NRYR

Community based promotion on VCT acceptance among rural migrants in Shanghai, China.

Voluntary counseling and testing (VCT) plays an important integral role in response to the HIV/AIDS epidemic. However, VCT service has not been effectively utilized among rural migrants, a high risk group in China. In this study, we developed a community based intervention to examine if community mobilization with comprehensive VCT is more effective than current HIV preventions with routine VCT service in promoting VCT acceptability among rural migrants in Shanghai, China.A comprehensive intervention with community mobilization and comprehensive VCT services including community-based VCT and mobile VCT was implemented during 2007-2009. Three communities in Minhang District of Shanghai were randomly selected and were designed to receive community mobilization and comprehensive VCT, traditional VCT and none intervention, respectively. After 24 months intervention, effects were evaluated by comparing outcome indicators between the baseline (2,690 participants) and follow-up surveys (1,850 participants).A substantial increase in VCT acceptance was observed among community mobilization group (94.9% vs. 88.5%, P<0.001), whereas the reverse effect was seen in the traditional VCT group (86.1% vs. 94.6%, P<0.001) and control group (69.0% vs. 91.7%, P<0.001). Rural migrants from community mobilization group were more likely to accept VCT (OR = 2.91, 95% CI 1.69-4.97). Rural migrants from community mobilization group also showed significant increase in HIV/AIDS knowledge, positive attitude towards HIV positive individuals and condom use.Community mobilization with comprehensive VCT has significant impact on promotion of VCT acceptance and utilization among rural migrants in Shanghai. These findings provide evidence to support community mobilization as a suitable strategy for VCT promotion among rural migrants in Shanghai, China

Schematic diagram of the community-based intervention program in the three selected communities.

<p>Schematic diagram of the community-based intervention program in the three selected communities.</p

Knowledge, attitude, and practice of voluntary HIV counseling and testing and acceptance of HIV mass screening among survey participants^*.

*<p>Chi-squared test or Fisher's exact test was applied when necessary. P<0.05 was regarded as significant.</p>**<p>Including but not limited to general hospitals and clinics, antenatal clinics, physical examinations for employment or marriage license.</p

Sociodemographic characteristics of the baseline and follow-up survey participants^*.

*<p>Chi-squared test or Fisher's exact test was applied when necessary. P<0.05 was regarded as significant.</p

Multivariate logistic regression analysis of predictors for VCT acceptability among the follow-up survey participants^* (n = 1850).

*<p>Odds Ratios (OR) adjusted for other variables listed in this table by a logistic regression analysis. CI: confidence interval.</p

HIV/AIDS-related knowledge, attitude and sexual behavior among survey paritcipants before and after the intervention programme^*.

*<p>Chi-squared test or Fisher's exact test was applied when necessary. P<0.05 was regarded as significant.</p>**<p>With missing data.</p