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1.
Ocean Dynamics - A multi-decadal simulation of ocean circulation in the northern Gulf of Mexico produces strong submesoscale instabilities in the Mississippi/Atchafalaya plume fronts. The model... 相似文献
2.
A monthly mean climatology of the mixed layer depth (MLD) in the North Pacific has been produced by using Argo observations.
The optimum method and parameter for evaluating the MLD from the Argo data are statistically determined. The MLD and its properties
from each density profile were calculated with the method and parameter. The monthly mean climatology of the MLD is computed
on a 2° × 2° grid with more than 30 profiles for each grid. Two bands of deep mixed layer with more than 200 m depth are found
to the north and south of the Kuroshio Extension in the winter climatology, which cannot be reproduced in some previous climatologies.
Early shoaling of the winter mixed layer between 20–30°N, which has been pointed out by previous studies, is also well recognized.
A notable feature suggested by our climatology is that the deepest mixed layer tends to occur about one month before the mixed
layer density peaks in the middle latitudes, especially in the western region, while they tend to coincide with each other
in higher latitudes. 相似文献
3.
Argon and nitrogen isotopes of air in polar ice cores provide constraints on past temperature and firn thickness, with relevance to past climate. We developed a method to simultaneously measure nitrogen and argon isotopes in trapped air from the same sample of polar ice. This method reduces the time required for analysis, allowing large numbers of measurements. We applied this method to the entire Holocene sequence of the GISP2 ice core (82.37-1692.22 m) with a 10-20 year sampling interval (670 depths). δ40Ar and δ15N show elevated values in the oldest part of the dataset, consistent with a thicker firn layer and increased temperature gradient in the firn due to the legacy of the abrupt warming at the end of the Younger Dryas interval and the gradual warming during the Preboreal interval (11.5-10.0 ka). The Preboreal Oscillation and the 8.2k event are clearly recorded. The data show remarkable stability after the 8.2k event.Available data suggests that post-coring gas loss involves two distinct types of fractionation. First, smaller molecules with less than a certain threshold size leak through the ice lattice with little isotopic fractionation. Second, gas composition changes via gas loss through microcracks, which induces isotopic fractionation. These two gas loss processes can explain most trends in our data and in other ice core records. 相似文献
4.
Intensive water sampling in conjunction with hydrological observations was conducted during three different rainstorms in order to understand the effects of rainfall events on the temporal variation of streamwater chemistry in a small headwater forest catchment. Concentrations of Na+ and SO42? decreased as the discharge rate increased. Hydrograph separation of the components was made using the three‐component model based on the end‐members mixing analysis (EMMA). The three end‐members were:
- 1 the groundwater in the saturated zone that prescribes the chemistry of the baseflow;
- 2 the throughfall that dilutes the streamwater;
- 3 the groundwater in the transient saturated zone prescribed, which was dependent on the groundwater level.
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6.
TIDAL FEATURES IN THE CHINA SEAS AND THEIR ADJACENT SEA AREAS AS DERIVED FROM TOPEX／POSEIDON ALTIMETER DATA 总被引：2，自引：0，他引：2
Some important tidal features of 8 major tidal constituents (M2, S2, K1, O1, P1,Sa, N2 and K2 ) in the china Seas and their adjacent sea areas were obtained using six years‘ TOPEX/POSEIDON altimeter data. The results showed that the obtained co-tidal and co-range charts for these major tidal constituents agreed well with those of previous researches using observational data from coastal tidal gauge stations and numerical models. 相似文献
7.
N. Hurlburt M. Cheung C. Schrijver L. Chang S. Freeland S. Green C. Heck A. Jaffey A. Kobashi D. Schiff J. Serafin R. Seguin G. Slater A. Somani R. Timmons 《Solar physics》2012,275(1-2):67-78
The immense volume of data generated by the suite of instruments on the Solar Dynamics Observatory (SDO) requires new tools for efficient identifying and accessing data that is most relevant for research. We have developed the Heliophysics Events Knowledgebase (HEK) to fill this need. The HEK system combines automated data mining using feature-detection methods and high-performance visualization systems for data markup. In addition, web services and clients are provided for searching the resulting metadata, reviewing results, and efficiently accessing the data. We review these components and present examples of their use with SDO data. 相似文献
8.
Response of the North Pacific subtropical countercurrent and its variability to global warming 总被引：1，自引：0，他引：1
Response of the North Pacific subtropical countercurrent (STCC) and its variability to global warming is examined in a state-of-the-art
coupled model that is forced by increasing greenhouse gas concentrations. Compared with the present climate, the upper ocean
is more stratified, and the mixed layer depth (MLD) shoals in warmer climate. The maximum change of winter MLD appears in
the Kuroshio–Oyashio extension (KOE) region, where the mean MLD is the deepest in the North Pacific. This weakens the MLD
front and reduces lateral induction. As a result of the reduced subduction rate and a decrease in sea surface density in KOE,
mode waters form on lighter isopycnals with reduced thickness. Advected southward, the weakened mode waters decelerate the
STCC. On decadal timescales, the dominant mode of sea surface height in the central subtropical gyre represents STCC variability.
This STCC mode decays as CO2 concentrations double in the twenty-first century, owing both to weakened mode waters in the mean state and to reduced variability
in mode waters. The reduced mode-water variability can be traced upstream to reduced variations in winter MLD front and subduction
in the KOE region where mode water forms. 相似文献
9.
A monthly mean time series of the temperature profile in the recirculation gyre south of the Kuroshio Extension has been produced
for the period 1971–2007 to examine temporal variations of the winter mixed layer. The winter mixed layer depth (MLD) shows
both interannual and decadal variations and is significantly correlated with variation of the mean net surface heat flux in
late autumn to early winter. There is also a close relation with the strength of pre-existing subsurface stratification, measured
as vertical temperature gradients in the preceding summer. Linear multiple regression analysis shows that a significant fraction
of the variations in the winter MLD is explained by the surface heat flux and the strength of the stratification. The contribution
of the two factors is comparable. 相似文献
10.
Naoto Iwasaka Fumiaki Kobashi Yosuke Kinoshita Yuko Ohno 《Journal of Oceanography》2006,62(4):481-492
A seasonal evolution of surface mixed layer in the western North Pacific around 24°N between 143°E and 150°E was observed
by using an Argo float for more than 9 months, from December 2001 through August 2002. The result showed that the mixed layer
deepened gradually in the first two months. It reached its maximum depth of about 130 m at the end of January, after which
the mixed layer varied largely and sometimes the pycnocline below the mixed layer was much weakened until the summer mixed
layer formed in late April. The thin surface mixed layer was maintained during the rest of the observation period. Heat budget
analysis suggests that the vertical and horizontal temperature advections are the two most dominant terms in the heat balance
in the upper layer on time scales from a few days to a month. The vertical motions that are possibly responsible for the vertical
temperature advection are discussed. 相似文献