Daily Archives: February 2, 2014

East Asian monsoon tied to solar variability

Liang Zhao, and Jing-Song Wang. Robust response of the East Asian monsoon rainband to solar variability. Journal of Climate 2014; doi: http://dx.doi.org/10.1175/JCLI-D-13-00482.1

This study provides evidence of robust response of the East Asian monsoon rainband to 11-year solar cycle and first identify the exact time period within the summer half-year (1958–2012) with the strongest correlation between the mean latitude of the rainband (MLRB) over China and the sunspot number (SSN). This period just corresponds to the climatological mean East Asian Meiyu season, characterized by a large-scale quasi-zonal monsoon rainband (i.e., 22 May to 13 July). Both the statistically significant correlation and the temporal coincidence indicate a robust response of the Meiyu rainband to solar variability during the last five solar cycles. During the high-SSN years, the Meiyu MLRB lies 1.2° farther north and the amplitude of its interannual variations increases when compared with low-SSN years. The robust response of monsoon rainband to solar forcing is related to an anomalous general atmospheric pattern with an up-down seesaw and a north-south seesaw over East Asia.

Click here for full paper (fee).

Ceramic water filter intervention, achieving sustainability

Mellor J, Abebe L, Ehdaie B, Dillingham R, Smith J. Modeling the sustainability of a ceramic water filter intervention. Water Research 2014 Feb 1; Vol. 49, pp. 286-99.

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Ceramic water filters (CWFs) are a point-of-use water treatment technology that has shown promise in preventing early childhood diarrhea (ECD) in resource-limited settings. Despite this promise, some researchers have questioned their ability to reduce ECD incidences over the long term since most effectiveness trials conducted to date are less than one year in duration limiting their ability to assess long-term sustainability factors. Most trials also suffer from lack of blinding making them potentially biased. This study uses an agent-based model (ABM) to explore factors related to the long-term sustainability of CWFs in preventing ECD and was based on a three year longitudinal field study. Factors such as filter user compliance, microbial removal effectiveness, filter cleaning and compliance declines were explored. Modeled results indicate that broadly defined human behaviors like compliance and declining microbial effectiveness due to improper maintenance are primary drivers of the outcome metrics of household drinking water quality and ECD rates. The model predicts that a ceramic filter intervention can reduce ECD incidence amongst under two year old children by 41.3%. However, after three years, the average filter is almost entirely ineffective at reducing ECD incidence due to declining filter microbial removal effectiveness resulting from improper maintenance. The model predicts very low ECD rates are possible if compliance rates are 80-90%, filter log reduction efficiency is 3 or greater and there are minimal long-term compliance declines. Cleaning filters at least once every 4 months makes it more likely to achieve very low ECD rates as does the availability of replacement filters for purchase. These results help to understand the heterogeneity seen in previous intervention-control trials and reemphasize the need for researchers to accurately measure confounding variables and ensure that field trials are at least 2-3 years in duration. In summary, the CWF can be a highly effective tool in the fight against ECD, but every effort should be made by implementing agencies to ensure consistent use and maintenance.

Click here for full paper (fee).