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21.
Journal of Oceanography - The authors examine small-scale spatiotemporal variability of the layer nearly 2000-m depth, which is the “bottom” of the present Argo observation system,... 相似文献
22.
Kohtaro Hosoda Hiroshi Murakami Akira Shibata Futoki Sakaida Hiroshi Kawamura 《Journal of Oceanography》2006,62(3):291-291
ADEOS-II Ocean: Advanced Earth Observing Satellite-II Ocean
Preface 相似文献23.
Hideharu Sasaki Shang-Ping Xie Bunmei Taguchi Masami Nonaka Shigeki Hosoda Yukio Masumoto 《Journal of Oceanography》2012,68(1):93-111
Interannual variations of the Hawaiian Lee Countercurrent (HLCC) in the 2000s were investigated using satellite and Argo profiling
float observations. The satellite-observed sea surface height shows that the geostrophic eastward current was anomalously
strong to the west away from Hawaii in 2003 and 2005. However, the trade winds and the orographic wind curl dipole in the
lee of Hawaii that drives the climatological mean HLCC were not particularly strong in these years, suggesting that the accelerations
of the HLCC were not caused by the wind stress curl forcing around Hawaii and subsequent Rossby wave propagation. Using Argo
observations, we found negative potential vorticity (PV) anomalies in the subsurface north of the HLCC in these 2 years. The
pycnocline is lifted northward as low PV waters of different densities stack up in the vertical, and the HLCC is then accelerated
via the thermal wind. The intensification and/or southward intrusion of the eastern subtropical mode water and subtropical
mode water seem to have induced negative PV anomalies in 2003 and 2005, respectively. Using high-resolution ocean simulations,
we confirmed the migrations of PV anomalies and their contributions to the HLCC accelerations. Although the HLCC is located
away from the cores of major mode waters, our results suggest that interannual variations of the HLCC are affected by those
of mode waters. 相似文献
24.
Kohtaro Hosoda 《Journal of Oceanography》2013,69(5):631-646
An empirical method has been developed for estimation of sea surface temperature (SST) at dawn and noon in local time from microwave observations at other times of the day. By using solar radiation, microwave sea surface wind, and SSTs, root-mean-square differences were reduced to approximately 0.75 and 0.8 °C for dawn and noon, respectively. The pseudo SST variation and spatial patterns found in daily mean SST values by simple averaging of samples were damped down by use of diurnal correction. The satellite SST with the diurnal correction shows highly significant coherent variation with in-situ measurements. 相似文献
25.
Hiroshi Kawamura Huiling Qin Kohtaro Hosoda Futoki Sakaida Chunhua Qiu 《Journal of Oceanography》2010,66(6):855-864
Producing high-quality match-ups coupling the Japanese geostationary satellite, Himawari-6 (H6), and buoy SST observations,
we have developed the new SST retrieval method. Kawamura et al. (2010) developed the previous version of SST product called MTSAT SST, which left several scientific/technical questions.
For solving them, 6,711 algorithm tuning match-ups with precise navigation and 240,476 validation match-ups are generated
for covering all seasons and wide ocean coverage. For discriminating the previous MTSAT SST, we call the new version of SST
H6 SST. It is found that the SZA dependences of MTSAT SST algorithm are different from area to area of SZA > 40–50° N/S. The
regionally different SZA dependences are treated by dividing the H6 disk coverage into five areas by the latitude lines of
40° N/S first and the longitude lines of 100° K and 180° K. Using the algorithm tuning match-ups, Nonlinear SST (NLSST) equations
are derived for all of the five areas. Though the sun zenith angle dependency correction term is also examined, there is no
significant regional difference. Therefore, this term is used in the H6 SST algorithm again. The new H6 SST equation is formed
by the areal NLSST and the sun zenith angle dependency term for each area. The statistical evaluation of H6 SST using the
validation match-ups show the small negative biases and the RMS errors of about 0.74° K for each area. For the full H6 disk,
the bias is −0.1° K and the RMS error 0.74° K. The histogram of H6 SST minus the in situ SST for each area has a similar Gaussian shape with small negative skewness, and the monthly validation of H6 SST for each
area is consistent with those for the whole period and the histograms 相似文献
26.
Hiroshi Murakami Kosei Sasaoka Kohtaro Hosoda Hajime Fukushima Mitsuhiro Toratani Robert Frouin B. Greg Mitchell Mati Kahru Pierre-Yves Deschamps Dennis Clark Stephanie Flora Motoaki Kishino Sei-Ichi Saitoh Ichio Asanuma Akihiko Tanaka Hiroaki Sasaki Katsumi Yokouchi Yoko Kiyomoto Hiroaki Saito Cécile Dupouy Absornsuda Siripong Satsuki Matsumura Joji Ishizaka 《Journal of Oceanography》2006,62(3):373-393
The Global Imager (GLI) aboard the Advanced Earth Observing Satellite-II (ADEOS-II) made global observations from 2 April
2003 to 24 October 2003. In cooperation with several institutes and scientists, we obtained quality controlled match-ups between
GLI products and in-situ data, 116 for chlorophyll-a concentration (CHLA), 249 for normalized water-leaving radiance (nLw) at 443 nm, and 201 for
aerosol optical thickness at 865 nm (Tau_865) and Angstrom exponent between 520 and 865 nm (Angstrom). We evaluated the GLI
ocean color products and investigated the causes of errors using the match-ups. The median absolute percentage differences
(MedPD) between GLI and in-situ data were 14.1–35.7% for nLws at 380–565 nm, 52.5–74.8% nLws at 625–680 nm, 47.6% for Tau_865, 46.2% for Angstrom, and 46.6%
for CHLA, values that are comparable to the ocean-color products of other sensors. We found that some errors in GLI products
are correlated with observational conditions; nLw values were underestimated when nLw at 680 nm was high, CHLA was underestimated
in absorptive aerosol conditions, and Tau_865 was overestimated in sunglint regions. The error correlations indicate that
we need to improve the retrievals of the optical properties of absorptive aerosols and seawater and sea surface reflection
for further applications, including coastal monitoring and the combined use of products from multiple sensors. 相似文献
27.
Abstract The 1999 Chi-Chi earthquake in Taiwan ( M w = 7.6) produced a surface rupture along the north–south-striking Chelungpu thrust fault with pure dip-slip (east side up) and left lateral strike-slip displacements. Near-field strong-motion data for the northern part of the fault illustrate a distinct lack of the high-frequency seismic radiation associated with a large slip (10–15 m) and a rapid slip velocity (2–4 m/s), suggesting a smooth seismic slip associated with low dynamic frictional resistance on the fault. A drillhole was constructed at shallow depths in the possible fault zones of the northern part of the Chelungpu Fault, which may have slipped during the 1999 earthquake. One of the zones consists of a 20-cm-thick, unconsolidated fault breccia with a chaotic texture lacking both discrete slip surfaces (e.g. Riedel shears) and grain crushing. Other possible fault zones are marked by the narrow (less than a few centimeters) gouge zone in which clayey material intrudes into the damaged zone outside of the gouge zone. These characteristic fault rock textures suggest that the slip mechanisms at shallow levels during the earthquake involved either granular flow of initially unconsolidated material or slip localization under elevated pore pressure along the narrow clayey gouge zone. Because both mechanisms lead to low dynamic frictional resistance on the fault, the rapid seismic slip in the deep portions of the fault (i.e. the source region of strong-motion radiation) could have been accommodated by frictionless slip on the shallow portions of the fault. The combination of strong-motion data and fault rock analysis suggests that smooth slip associated with low dynamic friction occurred on both the deep and shallow portions of the fault, resulting in a large slip between the source region and the surface in the northern region. 相似文献
28.
The role of meso-scale eddies in mixed layer deepening and mode water formation in the western North Pacific 总被引:2,自引:1,他引:2
Shinya Kouketsu Hiroyuki Tomita Eitarou Oka Shigeki Hosoda Taiyo Kobayashi Kanako Sato 《Journal of Oceanography》2012,68(1):63-77
Distributions of mixed layer depths around the centers of anti-cyclonic and cyclonic eddies in the North Pacific Ocean were
composited by using satellite-derived sea surface height anomaly data and Argo profiling float data. The composite distributions
showed that in late winter, deeper mixed layers were more (less) frequently observed inside the cores of the anti-cyclonic
(cyclonic) eddies than outside. This relationship was the clearest in the region of 140°E–160°W and 35°N–40°N, where the temperature
and salinity of the deep mixed layers were similar to those of the lighter variety of central mode water (L-CMW). A simple
one-dimensional bulk mixed layer model showed that both strong sea-surface heat and momentum fluxes and weak preexisting stratification
contributed to formation of the deep mixed layer. These conditions were associated with the anti-cyclonic eddies, suggesting
that these eddies are important in the formation of mode waters, particularly L-CMW. 相似文献
29.
Research and development of the New Generation Sea Surface Temperature for Open Ccean (NGSST-O) product and its demonstration operation 总被引:1,自引:0,他引:1
Futoki Sakaida Hiroshi Kawamura Shin Takahashi Teruhisa Shimada Yoshimi Kawai Kohtaro Hosoda Lei Guan 《Journal of Oceanography》2009,65(6):859-870
Real-time generation and distribution of the New Generation Sea Surface Temperature for Open Ocean (NGSST-O) product began
in September 2003 as a demonstration operation of the Global Ocean Data Assimilation Experiment (GODAE) High-Resolution Sea
Surface Temperature Pilot Project. Satellite sea surface temperature (SST) observations from infrared radiometers (AVHRR,
MODIS) and a microwave radiometer (AMSR-E) are objectively merged to generate the NGSST-O product, which is a quality-controlled,
cloud-free, high-spatial-resolution (0.05° gridded), wide-coverage (13–63° N, 116–166° E), daily SST digital map. The NGSST-O
demonstration operation system has been developed in cooperation with the Japanese Space Agency (JAXA) and has produced six
years of continuous data without gaps. Comparison to in situ SSTs measured by drifting buoys indicates that the root mean-square error of NGSST-O has been kept at approximately 0.9°C. 相似文献
30.
Global surface layer salinity change detected by Argo and its implication for hydrological cycle intensification 总被引:1,自引:0,他引:1
Shigeki Hosoda Toshio Suga Nobuyuki Shikama Keisuke Mizuno 《Journal of Oceanography》2009,65(4):579-586
We investigated changes in the global distribution of surface-layer salinity by comparing 2003–2007 Argo-float data with annual
mean climatological surface-layer salinity data for 1960–1989 from the World Ocean Database 2005. The two datasets showed
similar patterns, with low values in subpolar and tropical regions and higher values in the subtropics. The recent Argo data
indicate that the contrast between low and high salinity has intensified in all areas except the subpolar North Atlantic.
The intensified contrast of the surface layer salinity was maintaining for 2003–2007. Using a simple method, we attempted
to estimate evaporation and precipitation changes on the basis of surface-layer salinity changes. The results show a high
probability that the global hydrological cycle has increased in the past 30 years. 相似文献