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91.
Journal of Geographical Sciences - The North China Plain is one of the most water-stressed areas in China. Irrigation of winter wheat mainly utilizes groundwater resources, which has resulted in... 相似文献
92.
93.
Akihiko Murata Hidetaka Sasaki Mizuki Hanafusa Kazuo Kurihara 《Theoretical and Applied Climatology》2013,112(1-2):351-361
This study demonstrates that urban heat island (UHI) intensity can be estimated by comparing observational data and the outputs of a well-developed high-resolution regional climate model. Such an estimate is possible because the observations include the effects of UHI, whereas the model used does not include urban effects. Therefore, the errors in the simulated surface air temperature, defined as the difference between simulated and observed temperatures (simulated minus observed), are negative in urban areas but 0 in rural areas. UHI intensity is estimated by calculating the difference in temperature error between urban and rural areas. Our results indicate that overall UHI intensity in Japan is 1.5 K and that the intensity is greater in nighttime than in daytime, consistent with the previous studies. This study also shows that root mean square error and the magnitude of systematic error for the annual mean temperature are small (within 1.0 K). 相似文献
94.
Assessment of digital camera-derived vegetation indices in quantitative monitoring of seasonal rice growth 总被引:4,自引:0,他引:4
Toshihiro Sakamoto Michio Shibayama Akihiko Kimura Eiji Takada 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(6):872-882
A commercially available digital camera can be used in a low-cost automatic observation system for monitoring crop growth change in open-air fields. We developed a prototype Crop Phenology Recording System (CPRS) for monitoring rice growth, but the ready-made waterproof cases that we used produced shadows on the images. After modifying the waterproof cases, we repeated the fixed-point camera observations to clarify questions regarding digital camera-derived vegetation indices (VIs), namely, the visible atmospherically resistant index (VARI) based on daytime normal color images (RGB image) and the nighttime relative brightness index (NRBINIR) based on nighttime near infrared (NIR) images. We also took frequent measurements of agronomic data such as plant length, leaf area index (LAI), and aboveground dry matter weight to gain a detailed understanding of the temporal relationship between the VIs and the biophysical parameters of rice. In addition, we conducted another nighttime outdoor experiment to establish the link between NRBINIR and camera-to-object distance. The study produced the following findings. (1) The customized waterproof cases succeeded in preventing large shadows from being cast, especially on nighttime images, and it was confirmed that the brightness of the nighttime NIR images had spatial heterogeneity when a point light source (flashlight) was used, in contrast to the daytime RGB images. (2) The additional experiment using a forklift showed that both the ISO sensitivity and the calibrated digital number of the NIR (cDNNIR) had significant effects on the sensitivity of NRBINIR to the camera-to-object distance. (3) Detailed measurements of a reproductive stem were collected to investigate the connection between the morphological feature change caused by the panicle sagging process and the downtrend in NRBINIR during the reproductive stages. However, these agronomic data were not completely in accord with NRBINIR in terms of the temporal pattern. (4) The time-series data for the LAI, plant length, and aboveground dry matter weight could be well approximated by a sigmoid curve based on NRBINIR and VARI. The results confirmed that NRBINIR was more sensitive to all of the agronomic data for overall season, including the early reproductive stages. VARI had an especially high correlation with LAI, unless yellow panicles appeared in the field of view. 相似文献
95.
Rashid S. Al-Maamari Akihiko Hirayama Tsuyoshi Shiga Mark N. Sueyoshi Mahfoodh Al-Shuely Osman A. E. Abdalla Anvar R. Kacimov 《Environmental Earth Sciences》2011,63(6):1189-1198
Water table dynamics, dissolved oxygen (DO) content, electrical resistivity (ER) in monitoring wells and air pressure in the vadose zone are monitored in air sparging (AS) accompanied by soil vapor extraction (SVE) at a hydrocarbon-contaminated groundwater site in Oman, where a diesel spillover affected a heterogeneous unconfined aquifer. The formation of a groundwater mound at the early stage of air injection and potential lateral migration of contaminants from the mound apex called for an additional hydrodynamic barrier constructed as a pair of pump-and-treat (P&T) wells whose recirculation zone encompassed the AS and SVE wells. In all monitored piezometers the phreatic surface showed a rapid and distinct peak, which is attributed to the time of air breakthrough from the injection point to the vadose zone and a relatively mild recession limb interpreted as a decay of the mound. Tracer tests showed a layer of a relatively low hydraulic conductivity at an intermediate depth of the screened interval of the wells. Increased levels of DO and borehole air pressure that have been observed (as far as 50 m away) are likely mitigated by SVE and P&T. Radius of influence can be indirectly inferred from ER and DO changes in the AS operation zone. Salt tracer tests have shown that groundwater velocity within the AS zone decreases with the increase of air injection rate. 相似文献
96.
Characteristics of water mass under the surface mixed layer in Tsushima Straits and the southwestern Japan Sea in autumn 总被引:1,自引:0,他引:1
Tetsutaro Takikawa Akihiko Morimoto Goh Onitsuka Atsushi Watanabe Masatoshi Moku 《Journal of Oceanography》2008,64(4):585-594
Two different cold waters were found under the surface mixed layer in Tsushima Straits and the southwestern Japan Sea in autumn
2004. One is cold saline water with a low concentration of dissolved oxygen, and the other is cold less saline water with
a high concentration of dissolved oxygen. The older saline water originates from the bottom of the East China Sea, strongly
influenced by the Kuroshio water with high salinity. The bottom density in the eastern channel of the Tsushima Straits is
coincident with that of the East China Sea in autumn, corresponding to the season when the cold saline water was frequently
found in the Tsushima Straits. The newer less saline water originates from the front of Tsushima Warm Current between the
Tsushima Warm Current water and the surface cold water in the Japan Sea. This water is formed by subduction above the isopycnal
surface from the front of the Tsushima Warm Current. 相似文献
97.
98.
The Kamiomi, Sashima-gun (Iwai-shi), Ibaraki-ken, Japan, chondrite (observed to fall in spring, during the period 1913–6), consists of olivine, orthopyroxene, nickel-iron and troilite with minor amount of plagioclase, clinopyroxene, apatite and chromite. The average molar composition of olivine (Fa19) and orthopyroxene (Fs17) indicates that Kamiomi is a typical olivine bronzite chondrite. From the well-recrystallized texture, the presence of poorly-definable chondrules, homogeneous composition of olivine and absence of glass, this chondrite could be classified in petrologic type 5. The bulk chemical composition, especially, total Fe (27.33%) and metallic Fe (17.00%) as well as Fetotal/SiO2(0.72), Femetal/Fetotal (0–633) and SiO2/MgO (1.59) support the above conclusion. Coexistence of heavily-shocked olivine grains in the matrix composed of olivines and pyroxenes which suffered from light to moderate shock effect suggest that impacting phenomena, small-scaled but locally strong, occurred on the Kamiomi parent body. 相似文献
99.
Hiroyasu Ando Takeshi Noguchi Masao Nakagiri Akihiko Miyashita Yasumasa Yamashita Kyoji Nariai Hiroyoshi Tanabe 《Astrophysics and Space Science》1989,160(1-2):183-189
Two steps have been taken to decide at what place and altitude to set up the JNLT on Mauna Kea. First, the wind tunnel experiment has been made in collaboration with the Institute of Meteorology using the two models of summit area with the reduced scales of 1/1000 and 1/5000. This study tells us that the north-west cone is suitable for JNLT. Secondly, we have done the measurement of the microthermal activities in this area with a 30 m tower, which was continued for about 4 months in collaboration with the University of Hawaii. This experiment has given the mean vertical profile ofC
T
2
over 4 months and its scale height in the boundayr layer on our site. By use of these measurements, the contribution of the boundary layer to seeing is estimated. The behaviour ofC
T
2
under strong winds can be explained very well by topographic effects, which is in fairly good agreement with the results of our wind tunnel experiment.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988. 相似文献
100.