Comparison between MM5 simulations and satellite measurements during Typhoon Chanchu (2006) in the South China Sea

The fifth Pennsylvania State University and National Center for Atmospheric Research mesoscale model （MM5） is utilized to study the precipitation and wind speed during Typhoon Chanchu （2006）. Five model experiments with different physical parameterizations and sea surface temperature （SST） distributions are carried out. It is found that the control experiment configured with the Blakadar boundary scheme, Resiner2 moisture, the Betts-Miller cumulus scheme and daily updated SST has the most reasonable precipitation. The MRF boundary scheme tends to simulate a dryer boundary layer and stronger verticM mixing, which can greatly reduce the intensity of tropical cyclone （TC）, resulting in a smaller maximum wind speed but larger range of medium wind speed （25 30 m/s）. Constant SST through the TC cycle provides more energy from ocean surface, which could cause a significant increase in TC＇s intensity, thus resulting in the largest overestimation on rainfall and maximum wind speed. Longitudinally-uniform SST distribution before the rapid intensification could reduce TC＇s intensity and heat fluxes, which can partially compensate for the overestimation of precipitation in the control experiment.

ANALYSIS OF YELLOW SEA LOW FREQUENCY CURRENT VARIATION

Low frequency (LF) current (period】25 hour) variation at 5 stations in Jiaozhou Bay. Shijiousuo, and the central part of the Yellow Sea were studied by analyzing the observed long-period current data series in the study area.1) There are obvious periods of 3 and 5 days in the LF current spectra. The energy spectral value of LF current of a 5 day period is remarkably larger than that of a 3 day period. These periods reflect the correlations between the LF current variation and the LF water level variation.2) The feet that the 15-day period in the LF current spectra corresponds to the semi-monthly celestial tide period indicates that the tide-induced residual current is an important and most evident LF current component in the bay.3) The LF current spectral energy density in the northward direction is much larger than that in the eastward direction. This shows the frequency and strength of the wind field in the northward direction are evidently larger than that in the eastward direction.

Radiolarian record to paleoecological environment change events over the past 1.2 MaBP in the southern South China Sea

This note studies the Radiolarian fossil groups since 1.2 MaBP in ODP leg 184 site 1143, the southern South China Sea (SCS). The result shows that radiolarian abundance experienced a significant variation: before 0.9 MaBP it remained at the extremely low level, but increased with low extent between 0.9-0.65 Ma, which corresponded to the Mid-Pleistocene Transition stage, and it increased rapidly after 0.65 MaBP. During the whole process, the average abundance became higher and higher in each stage, and showed regularly periodic fluctuations. The obvious increase after 0.65 MaBP is inferred to result from the enhanced up-welling in this region, which was induced by the intensified monsoon circulation after the 'Mid-Pleistocene Transition'. An outstanding result of the spectral analyses is that a long oscillation of - 0.2 Ma cycle was found in the records of radiolarian abundance and complex diversity, which corresponds well to the result of other paleoceanographic indexes. This probably indicated a

Two Ultraviolet Radiation Datasets that Cover China

Ultraviolet（UV） radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization＇s measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.

Marine bacteria inhibit corrosion of steel via synergistic biomineralization

Metal corrosion often results in incalculable economic loss and significant safety hazards. Although numerous traditional methods have been used to mitigate the issue, such as coating and corrosion inhibitors, they are environmentally unfriendly and difficult to maintain. Therefore, in this study, an environmental approach was taken to protect steels from corrosion in a multi-species bacterial environment via synergistic biomineralization. The marine bacterium Pseudoalteromonas lipolytica mixed with Bacillus subtilis or Pseudomonas aeruginosa strains offered extraordinary corrosion protection for steel.The surface characterization and electrochemical tests showed that the biomineralized film generated by the mixed bacteria was more compact and protective than that induced by a single bacterium. Herein,we found that the synergistic mechanisms were rather different for the different bacterial groups. For Pseudoalteromonas lipolytica and Bacillus subtilis group, the related mechanisms were due to the increase of pH in the medium, secretion of carbonic anhydrase. As for Pseudoalteromonas lipolytica and Pseudomonas aeruginosa group, the synergistic mechanism was attributed to the inhibiting corrosive bacteria in biofilm by the growth advantage of Pseudoalteromonas lipolytica. Therefore, this study may introduce a new perspective for future use of biomineralization in a real marine environment.