Spatiotemporal variation and mechanisms of temperature inversion in the Bay of Bengal and the eastern equatorial Indian Ocean

In the northern Bay of Bengal,the existence of intense temperature inversion during winter is a widely accepted phenomenon.However,occurrences of temperature inversion during other seasons and the spatial distribution within and adjacent to the Bay of Bengal are not well understood.In this study,a higher resolution spatiotemporal variation of temperature inversion and its mechanisms are examined with mixed layer heat and salt budget analysis utilizing long-term Argo(2004 to 2020)and RAMA(2007 to 2020)profiles data in the Bay of Bengal and eastern equatorial Indian Ocean(EEIO).Temperature inversion exists(17.5%of the total 39293 Argo and 51.6%of the 28894 RAMA profiles)throughout the year in the entire study area.It shows strong seasonal variation,with the highest occurrences in winter and the lowest in spring.Besides winter inversion in the northern Bay of Bengal,two other regions with frequent temperature inversion are identified in this study for the first time:the northeastern part of the Bay of Bengal and the eastern part of the EEIO during summer and autumn.Driving processes of temperature inversion for different subregions are revealed in the current study.Penetration of heat(mean~25 W/m;)below the haline-stratified shallow mixed layer leads to a relatively warmer subsurface layer along with the simultaneous cooling tendency in mixed layer,which controls more occurrence of temperature inversion in the northern Bay of Bengal throughout the year.Comparatively lower cooling tendency due to net surface heat loss and higher mixed layer salinity leaves the southern part of the bay less supportive to the formation of temperature inversion than the northern bay.In the EEIO,slightly cooling tendency in the mixed layer along with the subduction of warm-salty Arabian Sea water beneath the cold-fresher Bay of Bengal water,and downwelling of thermocline creates a favorable environment for forming temperature inversion mainly during summer and autumn.Deeper isothermal layer depth,and thicker barrier layer thickness intensify the temperature inversion both in the Bay of Bengal and EEIO.

Wettability and interfacial behaviour of NdF_3-LiF-Nd_2O_3 on TiB_2-based ceramics

Wettability of TiB2-based ceramics by NdF3-LiF-Nd2O3 melt was studied using sessile drop technique in this paper. Wetting experiment was carried out under inert atmosphere at 1050 ℃. Chemical reactions which occurred on the solid-liquid interface and solid-gas interface during wetting process were discussed by thermodynamic calculations combined with X-ray diffraction （XRD） patterns. Micromorphology and element distribution of fracture surface at the interfacial region of solid/liquid system were analyzed by scanning electron microscope （SEM） equipped with energy dispersive spectrometry （EDS）. Contact angles of the drop were determined as a function of time in order to describe the wetting process, and wetting phenomenon was interpreted from a viewpoint of interface structure. The results showed that wetting was a dynamic wetting process with characteristics of reactive wetting. Penetration and oxidization phenomena during the experiment had great effect on wetting process.