Room-Temperature Phosphorescence and Lifetime of Fossil Resins (Amber) from Dominican Republic, Mexico, Baltic Sea, Myanmar, and Fushun, China

Amber can emit room temperature phosphorescence(RTP)under the well-known 365 nm fluorescence ultraviolet light.This paper is devoted to the phosphorescence study of 20 pieces of amber materials from the Dominican Republic,Mexico,Baltic sea,Myanmar,and Fushun,China.The results show that amber from the same geographic origin has similar shape in phosphorescence spectra.However,the shape of the amber phosphorescence spectra varies depending on their different localities.Burmite(amber from Myanmar)and Fushun amber have a bright yellow phosphorescence with a long lifetime,while the Dominican and Mexican ones are weaker and last shorter.The irradiation of Baltic amber becomes faint or even inert.Phosphorescence spectral Gaussian fitting results suggest an emission maximum near 550 nm in most amber samples.Their phosphorescence lifetime,analyzed through the exponential function fitting,is up to 1 second in Burmite and Fushun samples,shorter in the Dominican and Mexican ones,about 0.230 s,and the shortest in Baltic amber,close to 0.151 s.These variations of phosphorescence lifetime and intensity are related to the relative geological ages of these amber.It indicated that the phosphorescence agent was probably formed during the long geological time.While the anomaly occurred in Baltic amber,the only one found in a sea secondary deposit form,it demonstrated that the terrestrial geological environment these amber preserved has prevented the phosphorescence agent to be deactivated.

Circulation in the South China Sea is in a state of forced oscillation:Results from a simple reduced gravity model with a closed boundary

The South China Sea(SCS)is a narrow semi-enclosed basin,ranging from 4°–6°N to 21°–22°N meridionally.It is forced by a strong annual cycle of monsoon-related wind stress.The Coriolis parameter f increases at least three times from the southern basin to the northern basin.As a result,the basin-cross time for the first baroclinic Rossby wave in the southern part of the basin is about 10-times faster than that in the northern part,which plays the most vitally important role in setting the circulation.At the northernmost edge of SCS,the first baroclinic Rossby wave takes slightly less than 1 year to move across the basin,however,it takes only 1–2 months in the southernmost part.Therefore,circulation properties for a station in the model ocean are not solely determined by the forcing at that time instance only;instead,they depend on the information over the past months.The combination of a strong annual cycle of wind forcing and large difference of basin-cross time for the first baroclinic Rossby wave leads to a strong seasonal cycle of the circulation in the SCS,hence,the circulation is dominated by the forced oscillations,rather than the quasi-steady state discussed in many textbooks.The circulation in the SCS is explored in detail by using a simple reduced gravity model forced by seasonally varying zonal wind stress.In particular,for a given time snap the western boundary current in the SCS cannot play the role of balancing mass transport across each latitude nor balancing mechanical energy and vorticity in the whole basin.In a departure from the steady wind-driven circulation discussed in many existing textbooks,the circulation in the SCS is characterized by the imbalance of mechanical energy and vorticity for the whole basin at any part of the seasonal cycle.In particular,the western boundary current in the SCS cannot balance the mass,mechanical energy,and vorticity in the seasonal cycle of the basin.Consequently,the circulation near the western boundary cannot be interpreted in terms of the wind stress and thermohaline forcing at the same time.Instead,circulation properties near the western boundary should be interpreted in terms of the contributions due to the delayed wind stress and the eastern boundary layer thickness.In fact,there is a clear annual cycle of net imbalance of mechanical energy and vorticity source/sink.Results from such a simple model may have important implications for our understanding of the complicated phenomena in the SCS,either from in-situ observations or numerical simulations.