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791.
Diurnal Sea Surface Temperature (SST) variations and the near-surface thermal structure of the tropical hot event (HE) have
been investigated using advanced in-situ equatorial observations with hourly temporal resolution. The information on the HE
area defined by the satellite cloud-free SSTs is used to sample the in-situ observations. The in-situ SSTs sampled for the
HE conditions show that a maximum (minimum) SST has a histogram mode at 30.8°C (29.0°C), and frequently appears at 15:00 (07:00)
local time. The amplitude of the diurnal SST variation (DSST) is defined by the difference between the maximum and minimum
SSTs. The mean DSST during HEs is greater than 0.5°C, and has a maximum of about 0.75°C at the HE peak. The time series of
mean DSST gradually increases (rapidly decreases) before (after) the peak. The satellite SST has a systematic positive bias
against the corresponding daytime SST measured by the Triangle Trans-Ocean buoy Network. This bias is enhanced under conditions
of large in-situ DSST. One-dimensional numerical model simulation suggests that the systematic bias is caused by the sharp
vertical temperature gradient in the surface layer of HE. The near-surface thermal structure is generated by conditions of
high insolation and low wind speed, which is the typical HE condition. 相似文献
792.
Cédric Magen Gwénaëlle Chaillou Sean A. Crowe Alfonso Mucci Bjørn Sundby Aiguo Gao Ryosuke Makabe Hiroshi Sasaki 《Estuarine, Coastal and Shelf Science》2010
To establish the relative importance of terrigenous and marine organic matter in the southern Beaufort Sea, we measured the concentrations and the stable isotopic compositions of organic carbon and total nitrogen in sediments and in settling particles intercepted by sediment traps. The organic carbon content of surface sediment in the Chukchi and southern Beaufort Seas ranged from 0.6 to 1.6% dry wt., without a clear geographical pattern. The CORG:NTOT ratio ranged from 7.0 to 10.4 and did not vary significantly downcore at any one station. Values of δ13CORG and δ15NTOT in the sediment samples were strongly correlated, with the highest values, indicative of a more marine contribution, in the Amundsen Gulf. In contrast, the organic matter content, elemental (CORG:NTOT ratio) and isotopic (δ13CORG and δ15NTOT) composition of the settling particles was different from and much more variable than in the bottom sediments. The isotopic signature of organic matter in the Beaufort Sea is well constrained by three distinct end-members: a labile marine component produced in situ by planktonic organisms, a refractory marine component, the end product of respiration and diagenesis, and a refractory terrigenous component. A three-component mixing model explains the scatter observed in the stable isotope signatures of the sediment trap samples and accommodates an apparent two-component mixing model of the organic matter in sediments. The suspended matter in the water column contains organic matter varying from essentially labile and marine to mostly refractory and terrigenous. As it settles through the water column, the labile marine organic matter is degraded, and its original stable isotope signature changes towards the signature of the marine refractory component. This process continues in the bottom sediment with the result that the sedimentary organic matter becomes dominated by the refractory terrigenous and marine components. 相似文献