The equatorial response to subtropical Pacific forcing was studied in a coupled climate model.The forcings in the western,central and eastern subtropical Pacific all caused a significant response in the equatorial thermocline,with comparable magnitudes.This work highlights the key role of air-sea coupling in the subtropical impact on the equatorial thermocline,instead of only the role of the ＂oceanic tunnel＂.The suggested mechanism is that the cyclonic （anticyclonic） circulation in the atmosphere caused by the subtropical surface warming （cooling） can generate an anomalous upwelling （downwelling） in the interior region.At the same time,an anomalous downwelling （upwelling） occurs at the equatorward flank of the forcing,which produces anomalous thermocline warming （cooling）,propagating equatorward and resulting in warming （cooling） in the equatorial thermocline.This is an indirect process that is much faster than the ＂oceanic tunnel＂ mechanism in the subtropical impact on the equator.
Micronized coal reburning （MCR） can not only reduce carbon in fly ash but also reduce NOx emissions as compared to the conventional coal reburning. However, it has two major kinetic barriers in minimizing NOx emission. The first is the conversion of NO into hydrogen cyanide （HCN） by conjunction with various hydrocarbon fragments. The second is the oxidation of HCN by association with oxygen-containing groups. To elucidate the advantages of MCR, a combination of Diffuse Reflection Fourier Transform Infrared （FTIR） experimental studies with Density Functional Theory （DFT） theoretical calculations is conducted in terms of the second kinetic barrier. FTIR studies based on Chinese Tiefa coal show that there are five hydroxide groups such as OH-n, OH-N, OH- OR2, self-associated OH and free OH. The hydroxide groups increase as the mean particle size decreases expect for free OH. DFT calculations at the B3LYP/6-31 G（d） level indicate that HCN can be oxidized by hydroxide groups in three paths, HCN ＋ OH → HOCN ＋ H （path 1）, HCN ＋ OH → HNCO ＋ H （path 2）, and HCN ＋ OH -. CN ＋ H20 （path 3）. The rate limiting steps for path 1, path 2 and path 3 are IM2 → P1 ＋ H （170.66 kJ/mol activated energy）, IM1→IM3 （231.04 kJ/mol activated energy）, and R1 ＋ OH→ P3 ＋ H2O （97.14 kJ/mol activated energy）, respectively. The present study of MCR will provide insight into its lower NOx emission and guidance for further studies.
