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81.
S. Tsuneta T. Takakura N. Nitta K. Ohki K. Makishima T. Murakami M. Oda Y. Ogawara 《Solar physics》1983,86(1-2):313-321
This paper presents studies of the vertical structure of hard X-ray flares for two contrasting examples. The 1981 May 13 flare contained a coronal hard X-ray source which was located above 50000 km above the photosphere. On the other hand, the 1981 July 20 flare had a chromospheric double source structure in the initial phase. Electrons in this case were able to stream freely from the corona to the chromosphere. 相似文献
82.
Observations were made to study the oceanographic structure of the dense water formation and its outflow from Funka Bay, Hokkaido, during early spring. The winter Funka Bay water, which was transformed from the warm water of the Tsugaru Current, due to cooling and deep convection during the winter, flowed from the bay, while forming a frontal structure. The width and inclination of the density front were about 3 n. miles and 1.4×10?2, respectively, during the early spring of 1982. These values roughly coincided with calculated values of 2.6 n. miles and 1.7×10?2 using the sill flow model proposed by Whiteheadet al. (1974). Observed current speeds and directions were also similar to those predicted by the model. The renewal time of bay water with this flow was estimated to be about 51 days, which is consistent with the results of previous studies. 相似文献
83.
Robert Frouin Pierre-Yves Deschamps Lydwine Gross-Colzy Hiroshi Murakami Takashi Y. Nakajima 《Journal of Oceanography》2006,62(3):331-337
Top-of-atmosphere reflectance measured above the ocean in the visible and near infrared, after correction for molecular scattering,
may be linearly combined to retrieve surface chlorophyll-a abundance directly, without explicit correction for aerosol scattering
and absorption. The coefficients of the linear combination minimize the perturbing effects, which are modeled by a polynomial,
and they do not depend on geometry. The technique has been developed for Global Imager (GLI) spectral bands centered at 443,
565, 667, and 866 nm, but it is applicable to other sets of spectral bands. Theoretical performance is evaluated from radiation-transfer
simulations for a wide range of geophysical and angular conditions. Using a polynomial with exponents of −2, −1, and 0 to
determine the coefficients, the residual influence of the atmosphere on the linear combination is within ±0.001 in most cases,
allowing chlorophyll-a abundance to be retrieved with a root-mean-squared (RMS) error of 8.4% in the range 0.03–3 mgm−3. Application of the method to simulated GLI imagery shows that estimated and actual chlorophyll-a abundance are in agreement,
with an average RMS difference of 32.1% and an average bias of −2.2% (slightly lower estimated values). The advantage of the
method resides in its simplicity, flexibility, and rapidity of execution. Knowledge of aerosol amount and type is avoided.
There is no need for look-up tables of aerosol optical properties. Accuracy is adequate, but depends on the polynomial representation
of the perturbing effects and on the bio-optical model selected to relate the linear combination to chlorophyll-a abundance.
The sensitivity of the linear combination to chlorophyll-a abundance can be optimized, and the method can be extended to the
retrieval of other bio-optical variables. 相似文献
84.
Algorithm and validation of sea surface temperature observation using MODIS sensors aboard terra and aqua in the western North Pacific 总被引:4,自引:0,他引:4
Kohtaro Hosoda Hiroshi Murakami Futoki Sakaida Hiroshi Kawamura 《Journal of Oceanography》2007,63(2):267-280
A regional algorithm to estimate SST fields in the western North Pacific, where small oceanographic disturbance are often
found, has been developed using Moderate Resolution Imaging Spectroradiometers (MODIS) aboard Terra and Aqua. Its associated
algorithm, which includes cloud screening and SST estimation, is based on an algorithm for the Global Imager (GLI) aboard
Advanced Earth Observing Satellite-II (ADEOS-II) and is tuned for MODIS sensors. For atmospheric correction, we compare Multi-Channel
SST (MCSST), Nonlinear SST (NLSST), Water Vapor SST (WVSST) and Quadratic SST (QDSST) techniques. For NLSST, four first-guess
SSTs are investigated, including the values for MCSST, climatology with two different spatial resolutions, and near-real-time
objective analysis. The results show that the NLSST method using high-resolution climatological SST as a first-guess has both
good quality and high efficiency. The differences of root-mean-square error (RMSE) between the NLSST models using low-resolution
climatology and those using high-resolution climatology are up to 0.25 K. RMSEs of the new algorithm are 0.70 K/0.65 K for
daytime (Aqua/Terra) and 0.65 K/0.66 K for nighttime, respectively. Diurnal warming and the stratification of the ocean surface
layer under low wind are discussed. 相似文献
85.
Akihiko Murakami Kazunobu Suzuki Akiko Yamane Tadao Kusama 《Journal of Oceanography》1985,41(5):337-344
Microbial degradation of five crude oils such as Arabian light, Berri, Murban, Khafji and Minas crude oil by a pure bacterial strain,Pseudomonas sp. isolated from the sea water sampled at Kawasaki Harbor in Tokyo Bay, was studied experimentally in the enriched seawater medium.The degradation of crude oils was determined in total residual oil and in four fractions of saturated, aromatics, asphaltene and column residue by use of the column chromatography with activated alumina.The saturated fraction was shown to be most biodegradable. The aromatics followed for all five crude oils examined and the asphaltene was biodegradable to some extent. The column residue was not apparently degraded byPseudomonas sp. within 30 days. Each of Arabian light, Berri or Murban crude oil was degraded from 59 to 63.5 %, Khafji crude oil 49 % and Minas crude oil, solid at room temperature, only 33 %. Degradation rate of the five crude oils was determined to be in a range from 2.88 to 17.3 mg-oil 1–1 hr–1 or from 6.0×10–12 to 1.56×10–10 mg-oil cell–1 hr–1. Relative degradation ofn-paraffins of different carbon numbers in the saturated fraction was found to be similar regardless of carbon number for the five crude oils. 相似文献
86.
H. L. Davies J. Lock D. L. Tiffin E. Honza Y. Okuda F. Murakami K. Kisimoto 《Geo-Marine Letters》1987,7(3):143-152
The anticlinal nappe which forms the Huon Peninsula and adjacent ranges extends offshore as the Huon Ridge. The frontal thrust of the nappe is the Ramu-Markham Fault (onshore) and a deformation front along the line of the Markham Canyon (offshore). The timing and geometry of the Finisterre arc-continent collision is controversial, and the origin of the Finsch Deep is unresolved. 相似文献
87.
Masato Joshima Yoshihisa Okuda Fumitoshi Murakami Kiyoyuki Kishimoto Eiichi Honza 《Geo-Marine Letters》1986,6(4):229-234
Magnetic anomalies measured in the central to western half of the Solomon Sea, when considered with other magnetic data, reveal the existence of linear patterns. Magnetic lineation anomaly models of the Cenozoic, 65 to 0 Ma, suggest that an age between 34 and 28 Ma and a half-rate spreading speed of 5.8 cm/yr for the northern flank of a former spreading center best fits our present magnetic data in the Solomon Sea Basin. Heat flow and bathymetry data support this preferred model. 相似文献
88.
A simple, yet efficient and fairly accurate algorithm is presented to estimate photosynthetically available radiation (PAR)
at the ocean surface from Global Imager (GLI) data. The algorithm utilizes plane-parallel radiation-transfer theory and separates
the effects of the clear atmosphere and clouds, i.e., the planetary atmosphere is modeled as a clear atmosphere positioned
above a cloud layer. PAR is computed as the difference between the incident 400–700 nm solar flux at the top of the atmosphere
(known) and the solar flux reflected back to space by the atmosphere and surface (derived from GLI radiance), taking atmospheric
absorption into account. Knowledge of pixel composition is not required, eliminating the need for cloud screening and arbitrary
assumptions about sub-pixel cloudiness. For each GLI pixel, clear or cloudy, a daily PAR estimate is obtained. Diurnal changes
in cloudiness are taken into account statistically, using a regional diurnal albedo climatology based on 5 years of Earth
Radiation Budget Satellite (ERBS) data. The algorithm results are verified against other satellite estimates of PAR, the National
Centers for Environmental Prediction (NCEP) reanalysis product, and in-situ measurements from fixed buoys. Agreement is generally
good between GLI and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) estimates, with root-mean-squared (rms) differences of
7.9 (22%), 4.6 (13%), and 2.7 (8%) Einstein/m2/day on daily, weekly, and monthly time scales, and a bias of only 0.8–0.9 (about 2%) Einstein/m2/day. The rms differences between GLI and Visible and Infrared Spin Scan Radiometer (VISSR) estimates and between GLI and
NCEP estimates are smaller and larger, respectively, on monthly time scales, i.e., 3.0 (7%) and 5.0 (14%) Einstein/m2/day, and biases are 1.1 (2%) and −0.2 (−1%) Einstein/m2/day. The comparison with buoy data also shows good agreement, with rms inaccuracies of 10.2 (23%), 6.3 (14%), and 4.5 (10%)
Einstein/m2/day on daily, weekly, and monthly time scales, and slightly higher GLI values by about 1.0 (2%) Einstein/m2/day. The good statistical performance makes the algorithm suitable for large-scale studies of aquatic photosynthesis. 相似文献
89.
Constant flows, as well as oscillatory tidal flow, play an important role in the long-term dispersion of water in the Seto Inland Sea. Two kinds of numerical model (1-line and 2-line models) of the Seto Inland Sea have been developed to determine the role of density-induced currents, one type of the constant flow, in water dispersion in the Inland Sea. The seasonal variations of temperature, salinity and density fields are simulated and the density-induced current field is predicted at the same time. It is found that the most appropriate value of the longitudinal eddy diffusion coefficient,K
x, is 5×106–7×106 cm2sec–1. The value of the overall mean dispersion coefficient is of the order of 107cm2sec–1 (Hayami and Unoki, 1970). Consequently, it is suggested that 50–70% of the total dispersion in the Seto Inland Sea can be attributed to currents other than density-induced currents,i.e., tidal currents, tide-induced currents and wind-driven currents.In winter, both density and velocity fields, calculated using the 1-line model, satisfy the conditions for the existence of a coastal front in Kii Channel and in the eastern Iyo-nada. 相似文献
90.
Based on TBB data from Meteorological Institute Research of Japan, study is carried out of the features of seasonal transition of Asian-Australian monsoons and Asian summer monsoon establishment,indicating that the transition begins as early as in April, followed by abrupt change in May-June; the Asian summer monsoon situation is fully established in June. The winter convective center in Sumatra moved steadily northwestward across the "land bridge" of the maritime continent and the Indo-China Peninsula as time goes from winter to summer, thus giving rise to the change in large scale circulations that is responsible for the summer monsoon establishment over SE Asia and India; the South China Sea to the western Pacific summer monsoon onset bears a close relation to the active convection in the Indo China Peninsula and steady eastward retreat of the subtropical TBB high-value band,corresponding to the western Pacific subtropical high. 相似文献