Long-Term Variability of North Pacific Subtropical Mode Water in Response to Spin-Up of the Subtropical Gyre   总被引：1，自引：0，他引：1  

Tamaki Yasuda  Yoshiteru Kitamura 《Journal of Oceanography》2003,59(3):279-290

The Meteorological Research Institute's ocean general circulation model (MRI-OGCM) has been used to investigate the temperature variability of the North Pacific Subtropical Mode Water (NPSTMW) over a time series longer than 5 years via the spin-up of the subtropical gyre. Besides an interannual variation, the wintertime sea surface temperature in the area where the NPSTMW is formed, and the temperature of the NPSTMW itself, both change remarkably in a >5-year time scale. An analysis of heat budgets showed that the long-term changes in NPSTMW temperature are due mainly to a leading advection of heat by the Kuroshio Extension and compensating surface heat flux. As a result of a dynamical adjustment to the wind stress fields, the transports of the Kuroshio and the Kuroshio Extension increased in the mid 1970s with a lag of 3 years after the wind stress curl in the central North Pacific. The increased heat advection by the Kuroshio Extension induces a warming in the mixed layer in the NPSTMW formation area, followed by a warming of the NPSTMW itself. Both these warming actions increase the heat release to the atmosphere. These results imply that the surface heat flux over the Kuroshio Extension area varies in response to the change in the ocean circulation through the spin-up of the subtropical gyre. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

The Galactic Aberration and Its Impact on Astronomical Reference Frames     

《Chinese Astronomy and Astrophysics》2020,44(2):131-145

The Galactic aberration effect, also known as the secular aberration drift, is a consequence of the centripetal acceleration of the Solar System Barycenter in the circular orbit around the Galactic center. It causes distance-independent apparent proper motions (the amplitude is about 5 ${\mu \mathit{as}·\mathit{yr}}^{-1}$) for extragalactic sources which were regarded as motionless before 21th century. As the very long baseline interferometry (VLBI) has been greatly developed, and the ESA (European Space Agency) space mission Gaia has provided ultra high-precision astrometric data, the Galactic aberration effect has becoming important. It causes slow spin of the reference frame due to the non-uniform distribution of extragalactic sources. Therefore systematic corrections have to be applied to the Earth rotation parameters. For the precession rate, the correction is about 1 ${\mu \mathit{as}·\mathit{yr}}^{-1}$. For the very high accurate VLBI and Gaia reference frames, the Galactic aberration effect will introduce small distortion which is a crucial systematic effect for the link of the two reference frames.  相似文献   

Multiwavelength observations of the two unidentified EGRET sources 3EG J0616-3310 and 3EG J1249-8330     

N. La Palombara  R. P. Mignani  E. Hatziminaoglou  M. Schirmer  G. F. Bignami  P. Caraveo 《Astrophysics and Space Science》2007,309(1-4):209-213

We report on the X-ray and optical observation of the two unidentified EGRET sources 3EG J0616-3310 and 3EG J1249-8330. The X-ray coverage performed by the ESA space telescope XMM–Newton provided ∼150 X-ray sources within each of the two γ-ray error-circles. The optical follow-up carried on with the Wide Field Imager at the ESO/MPG 2.2 m telescope have found no candidate counterpart for 125 of these X-ray sources. Among these, we have selected 9 sources with f _X/f _opt≥100, which we consider promising INS candidates.  相似文献   

Constraints on the Formation Regions of Comets from their D:H Ratios     

Jonathan Horner  Olivier Mousis  Franck Hersant 《Earth, Moon, and Planets》2007,100(1-2):43-56

Studies of the D:H ratio in H₂O within the Solar nebula provide a relationship between the degree of enrichment of deuterium and the distance from the young Sun. In the context of cometary formation, such models suggest that comets which formed in different regions of the Solar nebula should have measurably different D:H ratios. We aim to illustrate how the observed comets can give information about the formation regions of the reservoirs in which they originated. After a discussion of the current understanding of the regions in which comets formed, simple models of plausible formation regions for two different cometary reservoirs (the Edgeworth–Kuiper belt and the Oort Cloud) are convolved with a deuterium-enrichment profile for the pre-solar nebula. This allows us to illustrate how different formation regions for these objects can lead to great variations in the deuterium enrichment distributions that we would observe in comets today. We also provide an illustrative example of how variations in the population within a source region can modify the resulting observational profile. The convolution of a deuterium-enrichment profile with examples of proto-cometary populations gives a feel for how observations could be used to draw conclusions on the formation region of comets which are currently fed into the inner Solar system from at least two reservoirs. Such observations have, to date, been carried out on only three comets, but future work with instruments such as ALMA and Herschel should vastly improve the dataset, leading to a clearer consensus on the formation of the Oort cloud and Edgeworth–Kuiper belt.  相似文献   

The distant activity of short-period comets – I     

E. Mazzotta Epifani  P. Palumbo  M. T. Capria  G. Cremonese  M. Fulle  L. Colangeli 《Monthly notices of the Royal Astronomical Society》2007,381(2):713-722

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Galaxy morphologies and environment in the Abell 901/902 supercluster from COMBO-17     

K. P. Lane  M. E. Gray  A. Aragón-Salamanca  C. Wolf  K. Meisenheimer 《Monthly notices of the Royal Astronomical Society》2007,378(2):716-722

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Three-dimensional cometary dust coma modelling in the collisionless regime: strengths and weaknesses     

M. J. Foster  S. F. Green 《Monthly notices of the Royal Astronomical Society》2007,377(3):1064-1084

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Diffuse UV light associated with the Spiderweb Galaxy: evidence for in situ star formation outside galaxies     

N. A. Hatch  R. A. Overzier  H. J. A. Röttgering  J. D. Kurk  G. K. Miley 《Monthly notices of the Royal Astronomical Society》2008,383(3):931-942

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Testing the accuracy of synthetic stellar libraries     

Lucimara P. Martins  Paula Coelho 《Monthly notices of the Royal Astronomical Society》2007,381(4):1329-1346

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The importance of mergers for the origin of intracluster stars in cosmological simulations of galaxy clusters     

Giuseppe Murante  Martina Giovalli  Ortwin Gerhard  Magda Arnaboldi  Stefano Borgani  Klaus Dolag 《Monthly notices of the Royal Astronomical Society》2007,377(1):2-16

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