How do Stability Corrections Perform in the Stable Boundary Layer Over Snow?     

Sebastian Schlögl  Michael Lehning  Kouichi Nishimura  Hendrik Huwald  Nicolas J. Cullen  Rebecca Mott 《Boundary-Layer Meteorology》2017,165(1):161-180

We assess sensible heat-flux parametrizations in stable conditions over snow surfaces by testing and developing stability correction functions for two alpine and two polar test sites. Five turbulence datasets are analyzed with respect to, (a) the validity of the Monin–Obukhov similarity theory, (b) the model performance of well-established stability corrections, and (c) the development of new univariate and multivariate stability corrections. Using a wide range of stability corrections reveals an overestimation of the turbulent sensible heat flux for high wind speeds and a generally poor performance of all investigated functions for large temperature differences between snow and the atmosphere above (>10 K). Applying the Monin–Obukhov bulk formulation introduces a mean absolute error in the sensible heat flux of \(6\,\hbox {W m}^{-2}\) (compared with heat fluxes calculated directly from eddy covariance). The stability corrections produce an additional error between 1 and \(5\,\hbox {W m}^{-2}\), with the smallest error for published stability corrections found for the Holtslag scheme. We confirm from previous studies that stability corrections need improvements for large temperature differences and wind speeds, where sensible heat fluxes are distinctly overestimated. Under these atmospheric conditions our newly developed stability corrections slightly improve the model performance. However, the differences between stability corrections are typically small when compared to the residual error, which stems from the Monin–Obukhov bulk formulation.  相似文献   

A review of fossil rhinoceroses from the Neogene of Myanmar with description of new specimens from the Irrawaddy Sediments   总被引：1，自引：0，他引：1  

Zin-Maung-Maung-Thein  Masanaru Takai  Takehisa Tsubamoto  Naoko Egi  Thaung-Htike  Takeshi Nishimura  Maung-Maung  Zaw-Win 《Journal of Asian Earth Sciences》2010,37(2):11

Four genera and one indeterminate genus (total eight species) of fossil rhinoceroses (Mammalia; Perissodactyla; Rhinocerotidae) are recognized from the Neogene of central Myanmar. In the early Miocene, most area of central Myanmar were under the shallow marine condition, and no rhinocerotid remain has been documented yet. During the middle to late Miocene, the rhinocerotid remains are commonly found and are represented by “Diceratherium” naricum, Brachypotherium perimense, Brachypotherium fatehjangense and an indeterminate rhinocerotid. In the latest Miocene, these archaic rhinoceroses became extinct. In the late Neogene, the extant genera, Rhinoceros (late Miocene to Pleistocene) and Dicerorhinus (Plio-Pleistocene) first appeared in Myanmar. They appear to have dispersed to the Island Southeast Asia from the continental Asia during the early Pleistocene to middle Pleistocene when the eustatic sea level became low remarkably.  相似文献   

Continuous measurement of methane flux over a larch forest using a relaxed eddy accumulation method   总被引：1，自引：0，他引：1  

Masahito Ueyama  Ken Hamotani  Wataru Nishimura  Yoshiyuki Takahashi  Nobuko Saigusa  Reiko Ide 《Theoretical and Applied Climatology》2012,109(3-4):461-472

We measured the methane flux of a forest canopy throughout a year using a relaxed eddy accumulation (REA) method. This sampling system was carefully validated against heat and CO₂ fluxes measured by the eddy covariance method. Although the sampling system was robust, there were large uncertainties in the measured methane fluxes because of the limited precision of the methane gas analyzer. Based on the spectral characteristics of signals from the methane analyzer and the diurnal variations in the standard deviation of the vertical wind velocity, we found the daytime and nighttime precision of half-hourly methane flux measurements to be approximately 1.2 and 0.7?μg?CH₄?m^?2?s^?1, respectively. Additional uncertainties caused by the dilution effect were estimated to affect the accuracy by as much as 0.21?μg?CH₄?m^?2?s^?1 on a half-hourly basis. Diurnal and seasonal variations were observed in the measured fluxes. The biological emission from plant leaves was not observed in our studies, and thus could be negligible at the canopy-scale exchange. The annual methane sink was 835?±?175?mg?CH₄?m^?2?year^?1 (8.35?kg?CH₄?ha^?1?year^?1), which was comparable to the flux range of 379–2,478?mg?CH₄?m^?2?year^?1 previously measured in other Japanese forest soils. This study indicated that the REA method could be a promising technique to measure canopy scale methane fluxes over forests, but further improvement of precision of the analyzer will be required.  相似文献   

High-time resolution AMS C data sets for Lake Baikal and Lake Hovsgol sediment cores: Changes in radiocarbon age and sedimentation rates during the transition from the last glacial to the Holocene   总被引：1，自引：1，他引：0  

Takahiro Watanabe  Toshio Nakamura  Fumiko Watanabe Nara  Takeshi Kakegawa  Kazuho Horiuchi  Ryoko Senda  Takefumi Oda  Mitsugu Nishimura  Genki Inoue Matsumoto  Takayoshi Kawai 《Quaternary International》2009,205(1-2):12

High-time resolution ¹⁴C dating of Lake Baikal sediment cores indicates negative and positive anomalies of calculated linear sedimentation rate (LSR; 1.1 and 35.6 cm/ka, respectively) during the period of climate transition from the last glacial to Holocene. The timing of the Lake Baikal apparent LSR anomalies is consistent with that of the changes in the atmospheric radiocarbon concentration (Δ¹⁴C) during Younger Dryas rapid cooling event. ¹⁴C dating of lipids in the Lake Baikal surface sediments revealed that the sources of sedimentary lipids were different in each basin. In the Northern Basin of Lake Baikal, the ¹⁴C age of total lipids from the surface sediment (4.0 ¹⁴C ka) was found to be older than that of TOC (1.6 ¹⁴C ka). By contrast, the ¹⁴C age of total lipids in the Southern Basin was younger than that of the TOC by ca. 0.7–3.0 ka.In the Lake Hovsgol sediment cores, ages of the main lithologic boundaries during the last glacial–interglacial transition were estimated based on new ¹⁴C data sets. TOC concentration in the cores started to rapidly increase at 13.8 ± 0.3 ¹⁴C ka at the base of the basinwide finely laminated layer deposited during Bølling/Allerød. The base of the layer diatomaceous mud corresponds to the end of Younger Dryas event (10.6 ± 0.1 ¹⁴C ka).  相似文献   

DEM-Based Analysis of Earthquake-Induced Shallow Landslide Susceptibility   总被引：3，自引：0，他引：3  

Shuichi Hasegawa  Ranjan Kumar Dahal  Toshiaki Nishimura  Atsuko Nonomura  Minoru Yamanaka 《Geotechnical and Geological Engineering》2009,27(3):419-430

  相似文献   

Development of the Emulsion Chamber Detector for Space Observations     

Yi-Ming Hu  Jin Chang  Yi-Zhong Gong  Ren-Jian Zhang  Nan-Sen Wang  He-Sen Tang  S. Torii  J. Nishimura  T. Kobayashi  Y. Shimizu  F. Makino 《Chinese Astronomy and Astrophysics》2008

The emulsion chamber detector on board the “ShiJian-8” satellite is the first one in China designed especially for observing in space the highenergy electrons and γ-rays. In this paper, the principle of the detector design, the method of data processing and the preliminary results of observations are introduced. The design lifetime of the detector is 15 days on the orbit, and the energy range of detectable particles is 100GeV∼5TeV.  相似文献   

空间乳胶室探测器的研制     

胡一鸣  常进  宫一忠  张仁健  王楠森  唐和森  Torii S.  Nishimura J.  Kobayashi T.  Shimizu Y.  Makino F. 《天文学报》2008,49(2):233-242

"实践八号"乳胶室探测器是我国首次用于空间观测高能电子及伽玛射线的乳胶 室探测器.介绍"实践八号"乳胶室探测器的设计原理、数据分析方法、设计过程和初步 观测结果等."实践八号"乳胶室探测器空间观测时间为15天,可探测的粒子能量范围为 100GeV～5TeV.  相似文献   

日本东北9.0级地震的同震与震后滑动   总被引：3，自引：0，他引：3  

Hisashi Suito  Mikio Tobita  张慧 《华南地震》2011,31(3):11-18

大部分强震都发生在海沟,那里是海洋板块向大陆板块俯冲的地方.大量矩震级MW9.0以上的地震发生在若干区域,包括智利,阿拉斯加,堪察加半岛和苏门答腊岛等.位于太平洋板块俯冲鄂霍茨克板块的日本海沟,历史记载上没有发生过MW9.0地震,除了至今震级还有争议的公元869年Jogan大地震[1](可能超过MW9.0).然而,根据...  相似文献   

Performances of Landfill Liners under Dry and Wet Conditions     

Saravanan Mariappan  Masashi Kamon  Faisal Haji Ali  Takeshi Katsumi  Tomoyuki Akai  Toru Inui  Masaki Nishimura 《Geotechnical and Geological Engineering》2011,29(5):881-898

This paper addresses the study conducted on the performance of landfill liner interface parameters. Interface shear strength parameters for various combinations of 9 different lining materials were studied and presented in this paper. This comprehensive testing program covers the interfaces between: (1) soil and compacted clay liner (CCL), (2) geomembrane (HDPEs or PVC) and soil, (3) geosynthetic clay liner (GCL)/CCL and soil, (4) geomembrane and geotextile, (5) geotextile and soil, (6) geotextile and GCL/CCL, and (7) geomembrane and GCL/CCL. The experiments were conducted for both at dry or optimum moisture condition and at saturated or wet condition. The interface performance under both conditions were compared to access the material performances. Tabulated summaries of interface test data under dry or optimum moisture condition (OMO) and saturated or wet condition are presented in the paper.  相似文献   

Submersible observations of manganese nodule and crust deposits on the Tenpo Seamount,Northwestern Pacific     

Akira Usui  Akira Nishimura  Kokichi Iizasa 《Marine Georesources & Geotechnology》2013,31(4):263-291

Pavements of manganese nodules and crusts and outcrops of Miocene limestones were observed on the flanks and flat top of the Tenpo Seamount during three Shinkai 2000 dives. The pre‐Miocene volcano supplied nuclei of volcanic rocks and hydrothermal manganese deposits, and subsequent slow or no sedimentation promoted deposition of abundant hydrogenetic nodules and crusts, mainly on the upper flank of the seamount. Nodule pavements generally cover calcareous sand surface sediments, while crusts cover hard outcrops composed probably of volcanic rocks. The fields of crusts and nodules are sparsely distributed with each other on scales of meters to tens of meters. The on‐site observation suggests the deposits have encountered tectonic and/or mass movements that resulted in unusual occurrences of densely stacked nodules and occasionally the nodules resting directly on crusts or hard substrates. Mineralogical and chemical compositions reveal that for nodules and crusts the encrusting manganese layers of around 1 cm thickness are composed of hydrogenetic vernadite, and diagenetic influence is negligible.  相似文献