The Hadley circulation is one of the most important atmospheric circulations. Widening of the Hadley circulation has drawn extensive studies in the past decade. The key concern is that widening of the Hadley circulation would cause poleward shift of the subtropical dry zone. Various metrics have been applied to measure the widening of the tropics. What are responsible for the observed widening trends of the Hadley circulation? How anthropogenic and natural forcings caused the widening? How the widening results in regional climatic effects? These are the major questions in studing the widening of the Hadley circulation. While both observations and simulations all show widening of the Hadley circulation in the past few decades, there are no general agreements of changes in the strength of the Hadley circulation. Although some reanalysis datasets show strengthening of the Hadley circulation, it was shown that the strengthening trend could be artificial, and simulations show weakening of the Hadley circulation for global greenhouse warming. In the present paper, we shall briefly review the major progresses of studies in trends in width and strength of the Hadley circulation. We address answers to these questions, clarify inconsistent results, and propose ideas for future studies.

T helper 17(Th17) cell is a new subset of CD4+ T cells that produce a proinflammatory cytokine interleukin‐17 (IL‐17). Th17 cells have recently been shown to play a critical role in many autoimmune diseases that had previously been thought to be Th1 dominant. Although Hashimoto’s thyroiditis (HT) was thought to be a Th1‐type disease, the contributions of Th17 cells to the pathogenesis remain unclear. In this study, we investigated the expression levels of Th1/Th17 cell‐associated factors in peripheral blood mononuclear cells (PBMC) and plasma from patients with HT by quantitative real‐time polymerase chain reaction (RT‐qPCR) and enzyme‐linked immunosorbent assay (ELISA). Our results showed that the expression levels of Th1 cells‐related T‐bet and interferon‐γ (IFN‐γ) mRNA in PBMC from HT significantly decreased. However, the mRNA of Th17 coherent retinoic acid‐related orphan nuclear receptor gamma t (RORγt) and IL‐17 in patients with HT increased. In addition, a negative correlation between T‐bet and RORγt mRNA expression was found in patients with HT, and the similar phenomena also appeared on the levels of mRNA and plasma concentration between IFN‐γ and IL‐17. It suggested that Th17 cells rather than Th1 cells predominated among patients suffering from HT, and Th17 cells might be involved in the pathogenesis of HT.

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Abstract. A data assimilation system (DAS) was developed for the Chinese Unified Atmospheric Chemistry Environment – Dust (CUACE/Dust) forecast system and applied in the operational forecasts of sand and dust storm (SDS) in spring 2006. The system is based on a three dimensional variational method (3D-Var) and uses extensively the measurements of surface visibility and dust loading retrieval from the Chinese geostationary satellite FY-2C. The results show that a major improvement to the capability of CUACE/Dust in forecasting the short-term variability in the spatial distribution and intensity of dust concentrations has been achieved, especially in those areas far from the source regions. The seasonal mean Threat Score (TS) over the East Asia in spring 2006 increased from 0.22 to 0.31 by using the data assimilation system, a 41% enhancement. The assimilation results usually agree with the dust loading retrieved from FY-2C and visibility distribution from surface meteorological stations, which indicates that the 3D-Var method is very powerful for the unification of observation and numerical modeling results.

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