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71.
72.
Ho Seong Hwang † Myung Gyoon Lee 《Monthly notices of the Royal Astronomical Society》2009,397(4):2111-2122
We present the results of a study of galaxy activity in two merging binary clusters (A168 and A1750) using the Sloan Digital Sky Survey (SDSS) data supplemented with the data in the literature. We have investigated the merger histories of A168 and A1750 by combining the results from a two-body dynamical model and X-ray data. In A168, two subclusters appear to have passed each other and to be coming together from the recent maximum separation. In A1750, two major subclusters appear to have started interaction and to be coming together for the first time. We find an enhanced concentration of the galaxies showing star formation (SF) or active galactic nuclei (AGN) activity in the region between two subclusters in A168, which were possibly triggered by the cluster merger. In A1750, we do not find any galaxies with SF/AGN activity in the region between two subclusters, indicating that two major subclusters are in the early stage of merging. 相似文献
73.
Young Baek Son Wilford D. Gardner Alexey V. Mishonov Mary Jo Richardson 《Journal of Earth System Science》2009,118(1):1-10
Hydrographic data, including particulate organic carbon (POC) from the Northeastern Gulf of Mexico (NEGOM) study, were combined
with remotely-sensed SeaWiFS data to estimate POC concentration using principal component analysis (PCA). The spectral radiance
was extracted at each NEGOM station, digitized, and averaged. The mean value and spurious trends were removed from each spectrum.
De-trended data included six wavelengths at 58 stations. The correlation between the weighting factors of the first six eigenvectors
and POC concentration were applied using multiple linear regression. PCA algorithms based on the first three, four, and five
modes accounted for 90, 95, and 98% of total variance and yielded significant correlations with POC with R
2 = 0.89, 0.92, and 0.93. These full waveband approaches provided robust estimates of POC in various water types.
Three different analyses (root mean square error, mean ratio and standard deviation) showed similar error estimates, and suggest
that spectral variations in the modes defined by just the first four characteristic vectors are closely correlated with POC
concentration, resulting in only negligible loss of spectral information from additional modes. The use of POC algorithms
greatly increases the spatial and temporal resolution for interpreting POC cycling and can be extrapolated throughout and
perhaps beyond the area of shipboard sampling. 相似文献
74.
Acta Geochimica - In this study, we investigated the chemical composition of dissolved solids in the Ca River basin, North-Central Vietnam. Water samples were collected from August 2017 to July... 相似文献
75.
76.
Assimilation of Hourly Surface Observations with the Canadian High-Resolution Ensemble Kalman Filter
An hourly-cycling ensemble Kalman filter (EnKF) working at 2.5?km horizontal grid spacing is implemented over southern Ontario (Canada) to assimilate Meteorological Terminal Aviation Routine Weather Reports (METARs) in addition to the observations assimilated operationally at the Canadian Meteorological Centre. This high-resolution EnKF (HREnKF) system employs ensemble land analyses and perturbed roughness length to prevent an ensemble spread that is too small near the surface. The HREnKF then performs continuously for a four-day period, from which twelve-hour ensemble forecasts are launched every six hours. The impact on analyses and short-term forecasts of assimilating METAR data is given special attention.It is shown that using ensemble land surface analyses increases near-surface ensemble spreads for temperature and specific humidity. Perturbing roughness length enlarges the spread for surface wind. Given sufficient ensemble spread, the four-day case study shows that the near-surface model state is brought closer to surface observations during the cycling process. The impact of assimilating surface data can also be seen at higher levels by using aircraft reports for verification. The ensemble forecast verification suggests that METAR data assimilation improves ensemble forecasts of air temperature and dewpoint near the surface up to a lead time of six hours or even longer. However, only minor improvement is found in surface wind forecasts. 相似文献
77.
I. INTRODUCTION Bordering the SW margin of the Red Basin of Szechuan runs a roughly N-S mountain range which includes such mountains as Washan, Omeishan and Talliangshan (Pl. I) and for the sake of convenience is designated with the name of Liangshan Range. Among these mountains only the geology of the Omeishan region is fairly well known in consequence of the works done by many a geologist; of the Washan region, though had been visited by 相似文献
78.
Jieun Baek 《International journal of geographical information science》2017,31(11):2234-2254
We developed a least-cost path analysis algorithm that satisfies a slope threshold condition in hilly terrain. The new algorithm uses an expanding moving-window to explore a combination of cells that satisfy an elevation threshold condition and then supplements this by executing cut and fill operations when there are obstacle cells between source and destination cells. Cut and fill factors regarding the difference in the actual elevation and revised elevation are considered and a least-cost path is analyzed after calculating the accumulated travel cost to the destination point. After applying the developed algorithm to synthetic and real-world data, the least accumulated travel cost from the source point can then be calculated for all cells on the raster surface by considering various slope thresholds, moving-window sizes and raster data resolutions. This algorithm can be implemented as a useful tool in GIS software as well as engineering design software utilized in the construction and mining industries. 相似文献
79.
The presence of the minimum salinity and oxygen-rich East Sea Intermediate Water (ESIW) off Korean coast has raised many questions
about its origin and movement. This study attempts to answer these questions in the context of numerical model. For this,
the Miami Isopycnic Coordinate Ocean Model is used with surface and inflow boundary conditions based on available data. Model
results show that the ESIW forms most distinctly off Vladivostok, where the center of doming structure is observed, and moves
southward along Korean coast forming a large cyclonic gyre around the doming. The renewed ESIW has the character of minimum
potential vorticity common to usual mode waters. These results are compatible with various indications made in previous observational
and theoretical studies. However, it is not known whether the doming structure is a result of convection or the latter is
favored by the former.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
80.