检索结果-内蒙古大学图书馆

JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2016年第6期33卷 1113-1122页

作者： Rudnick, Daniel L. Davis, Russ E. Sherman, Jeffrey T. Univ Calif San Diego Scripps Inst Oceanog 9500 Gilman DrMail Code 0213 La Jolla CA 92093 USA

Operational statistics for the Spray underwater glider are presented to demonstrate capabilities for sustained observations. An underwater glider is an autonomous device that profiles vertically by changing buoyancy and flies horizontally on wings. The focus has been on sustained observations of boundary currents to take advantage of the glider's small size, which allows it to be deployed and recovered from small vessels close to land, and the fine horizontal resolution delivered by the glider, which is scientifically desirable in boundary regions. Since 2004, Spray underwater gliders have been deployed for over 28 000 days, traveling over 560 000 km, and delivering over 190 000 profiles. More than 10 gliders, on average, have been in the water since 2012. Statistics are given in the form of histograms for 297 completed glider missions of longer than 5 days. The statistics include mission duration, number of dives, distance over ground, and horizontal and vertical distance through water. A discussion of problems, losses, and short missions includes a survival analysis. The most extensive work was conducted in the California Current system, where observations on three across-shorelines have been sustained, with 97% coverage since 2009. While the authors have certain advantages as developers and builders of the Spray underwater glider and Spray may have design and construction advantages, they believe these statistics are a sound basis for optimism about the widespread future of gliders in oceanographic observing.

关键词： observational techniques and algorithms In situ oceanic observations Profilers oceanic

来源：评论

学校读者我要写书评

暂无评论

A New Class of Quality Controls for Micrometeorological Data in Complex Tropical Environments

引用

JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2016年第1期33卷 169-183页

作者： Rollenbeck, Ruetger Trachte, Katja Bendix, Joerg Univ Marburg Fac Geog Lab Climatol & Remote Sensing Deutschhausstr 10 D-35032 Marburg Germany

Quality control is a particularly demanding problem for micrometeorological studies in complex environments. With the transition to electronic sensing and storage of climate data in high temporal resolution, traditional approaches of homogenization are insufficient for addressing the small-scale variability and spatial heterogeneity of the data. This problem can be successfully addressed by introducing a new class of control procedures based on the physical and climatological relations between different climate variables. The new approach utilizes knowledge about the interdependency of air temperature, precipitation, radiation, relative air humidity, cloud cover, and visibility to develop empirical functions for determining the probability margins for the co-occurrence of specific conditions in tropical mountains and deserts. It can also be applied to other geographic settings by adjusting the parameters derived from the data itself. All procedures are integrated into a processing chain with feedback loops and combined with conventional logical and statistical checks, which enables it to detect small errors that normally pass unnoticed. The algorithms are also adapted to incorporate the short time steps of the original data to retain the potential for detailed process analyses.

关键词： Geographic location/entity South America Physical Meteorology and Climatology Climate variability observational techniques and algorithms Data processing Data quality control Quality assurance/control Mathematical and statistical techniques Error analysis

来源：评论

学校读者我要写书评

暂无评论

On the Link between Tropical Cyclones and Daily Rainfall Extremes Derived from Global Satellite Observations

引用

JOURNAL OF CLIMATE 2016年第17期29卷 6127-6135页

作者： Prat, Olivier P. Nelson, Brian R. North Carolina State Univ Cooperat Inst Climate & Satellites Asheville NC 28801 USA NOAA Natl Ctr Environm Informat 151 Patton Ave Asheville NC 28801 USA NOAA Ctr Weather & Climate NESDIS NCEI Asheville NC 28801 USA

The authors evaluate the contribution of tropical cyclones (TCs) to daily precipitation extremes over land for TC-active regions around the world. From 1998 to 2012, data from the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA 3B42) showed that TCs account for an average of 3.5% +/- 1% of the total number of rainy days over land areas experiencing cyclonic activity regardless of the basin considered. TC days represent between 13% and 31% of daily extremes above 4 in. day(-1), but can account locally for the large majority (>70%) or almost all (approximate to 100%) of extreme rainfall even over higher latitude areas marginally affected by cyclonic activity. Moreover, regardless of the TC basin, TC-related extremes occur preferably later in the TC season after the peak of cyclonic activity.

关键词： Geographic location/entity Tropics Atm/Ocean Structure/ Phenomena Extreme events Rainfall Physical Meteorology and Climatology Hurricanes/typhoons Hydrometeorology observational techniques and algorithms Satellite observations

来源：评论

学校读者我要写书评

暂无评论

Atmospheric Rotors and Severe Turbulence in a Long Deep Valley

引用

JOURNAL OF THE ATMOSPHERIC SCIENCES 2016年第4期73卷 1481-1506页

作者： Strauss, Lukas Serafin, Stefano Grubisic, Vanda Univ Vienna Dept Meteorol & Geophys Althanstr 14 A-1090 Vienna Austria Natl Ctr Atmospher Res POB 3000 Boulder CO 80307 USA

The conceptual model of an atmospheric rotor is reexamined in the context of a valley, using data from the Terrain-Induced Rotor Experiment (T-REX) conducted in 2006 in the southern Sierra Nevada and Owens Valley, California. All T-REX cases with strong mountain-wave activity have been investigated, and four of them (IOPs 1, 4, 6, and 13) are presented in detail. Their analysis reveals a rich variety of rotorlike turbulent flow structures that may form in the valley during periods of strong cross-mountain winds. Typical flow scenarios in the valley include elevated turbulence zones, downslope flow separation at a valley inversion, turbulent interaction of in-valley westerlies and along-valley flows, and highly transient mountain waves and rotors. The scenarios can be related to different stages of the passage of midlatitude frontal systems across the region. The observations from Owens Valley show that the elements of the classic rotor concept are modulated and, at times, almost completely offset by dynamically and thermally driven processes in the valley. Strong lee-side pressure perturbations induced by large-amplitude waves, commonly regarded as the prerequisite for flow separation, are found to be only one of the factors controlling rotor formation and severe turbulence generation in the valley. Buoyancy perturbations in the thermally layered valley atmosphere appear to play a role in many of the observed cases. Based on observational evidence from T-REX, extensions to the classic rotor concept, appropriate for a long deep valley, are proposed.

关键词： Mountain meteorology Atm/Ocean Structure/ Phenomena North America observational techniques and algorithms Wind profilers Applications Valley/mountain flows Geographic location/entity Lidars/Lidar observations Wind gusts

来源：评论

学校读者我要写书评

暂无评论

Rain Type Classification Algorithm Module for GPM Dual-Frequency Precipitation Radar

引用

JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2016年第9期33卷 1887-1898页

作者： Awaka, Jun Le, Minda Chandrasekar, V. Yoshida, Naofumi Higashiuwatoko, Tomohiko Kubota, Takuji Iguchi, Toshio Tokai Univ Sapporo Hokkaido Japan Colorado State Univ Ft Collins CO 80523 USA Remote Sensing Technol Ctr Japan Tsukuba Ibaraki Japan Japan Aerosp Explorat Agcy Tsukuba Ibaraki Japan Natl Inst Informat & Commun Technol Koganei Tokyo Japan

The Global Precipitation Measurement (GPM) Dual-Frequency Precipitation Radar (DPR) algorithms consist of modules. This paper describes version 4 (V4) of GPM DPR level 2 (L2) classification (CSF) modules, which consist of two single-frequency (SF) modules-that is, Ku-only and Ka-only modules-and a dual-frequency (DF) module. Each CSF module detects bright band (BB) and classifies rain into three major types, that is, stratiform, convective, and other. The Ku-only and Ka-only CSF modules use algorithms that are similar to the Tropical Rainfall Measuring Mission (TRMM) rain type classification algorithm 2A23. The DF CSF module uses a new method called the measured dual-frequency ratio (DFRm) method for the rain type classification and the detection of BB. It is shown that the Ku-only CSF module and the DF CSF module produce almost indistinguishable rain type counts in a statistical sense. It is also shown that the DFRm method in the DF CSF module improves the detection of BB.

关键词： algorithms Atm/Ocean Structure/ Phenomena observational techniques and algorithms Precipitation Radars/Radar observations Remote sensing Satellite observations

来源：评论

学校读者我要写书评

暂无评论

Assimilation of Pseudo-GLM Data Using the Ensemble Kalman Filter

引用

MONTHLY WEATHER REVIEW 2016年第9期144卷 3465-3486页

作者： Allen, Blake J. Mansell, Edward R. Dowell, David C. Deierling, Wiebke Univ Oklahoma Cooperat Inst Mesoscale Meteorol Studies Norman OK 73019 USA NOAA Natl Severe Storms Lab OAR Norman OK 73069 USA NOAA Earth Syst Res Lab OAR Norman OK USA Natl Ctr Atmospher Res POB 3000 Boulder CO 80307 USA

Total lightning observations that will be available from the GOES-R Geostationary Lightning Mapper (GLM) have the potential to be useful in the initialization of convection-resolving numerical weather models, particularly in areas where other types of convective-scale observations are sparse or nonexistent. This study used the ensemble Kalman filter (EnKF) to assimilate real-data pseudo-GLM flash extent density (FED) observations at convection-resolving scale for a nonsevere multicell storm case (6 June 2000) and a tomadic supercell case (8 May 2003). For each case, pseudo-GLM FED observations were generated from ground-based lightning mapping array data with a spacing approximately equal to the nadir pixel width of the GLM, and tests were done to examine different FED observation operators and the utility of temporally averaging observations to smooth rapid variations in flash rates. The best results were obtained when assimilating 1-mM temporal resolution data using any of three observation operators that utilized graupel mass or graupel volume. Each of these three observation operators performed well for both the weak, disorganized convection of the multicell case and the much more intense convection of the supercell case. An observation operator using the noninductive charging rate performed poorly compared to the graupel mass and graupel volume operators, a result that appears likely to be due to the inability of the noninductive charging rate to account for advection of space charge after charge separation occurs.

关键词： Atm/Ocean Structure/ Phenomena Lightning observational techniques and algorithms Satellite observations Models and modeling Cloud resolving models Data assimilation Ensembles Numerical weather prediction/forecasting

来源：评论

学校读者我要写书评

暂无评论

Forest Degradation Associated with Logging Frontier Expansion in the Amazon: The BR-163 Region in Southwestern Para, Brazil

引用

EARTH INTERACTIONS 2016年第17期20卷 1-26页

作者： Pinheiro, T. F. Escada, M. I. S. Valeriano, D. M. Hostert, P. Gollnow, F. Mueller, H. Natl Inst Space Res INPE Ctr Earth Syst Sci Sao Jose Dos Campos Brazil Natl Inst Space Res INPE Ctr Earth Syst Sci Dept Image Proc Sao Jose Dos Campos Brazil Natl Inst Space Res INPE Amazonia Monitoring Program Dept Remote Sensing Sao Jose Dos Campos Brazil Humboldt Univ Geomat Lab Berlin Germany Humboldt Univ Dept Geog Berlin Germany

Forest degradation is the long-term and gradual reduction of canopy cover due to forest fire and unsustainable logging. A critical consequence of this process is increased atmospheric carbon emissions. Although this issue is gaining attention, forest degradation in the Brazilian Amazon has not yet been properly addressed. The claim here is that this process is not constant throughout Amazonia and varies according to colonization frontiers. Moreover, the accurate characterization of degradation requires lengthy observation periods to track gradual forest changes. The forest degradation process, the associated timeframe, spatial patterns, trajectories, and extent were characterized in the context of the Amazon frontiers of the 1990s using 28 years (1984-2011) of annual Landsat images. Given the large database and the characteristic of logging and burning, this study used data mining techniques and cell approach classification to analyze the spatial patterns and to construct associated trajectories. Multi-temporal analysis indicated that forest degradation in the last two decades has caused as many interannual landscape changes as have clear-cuts. In addition, selective logging, as a major aspect of forest degradation, affected a larger amount of forest land than did forest fire. Although a large proportion of logged forest was deforested in the following years, selective logging did not always precede complete deforestation. Instead, the results indicate that logged forests were abandoned for approximately 4 years before clearance. Throughout the forest degradation process, there were no recurrent forest fires, and loggers did not revisit the forest. Forest degradation mostly occurred as a result of a single selective logging event and was associated with low-intensity forest damage.

关键词： Geographic location/entity Amazon region observational techniques and algorithms Data mining Remote sensing Applications Deforestation

来源：评论

学校读者我要写书评

暂无评论

Climatology and Interannual Variability of Quasi-Global Intense Precipitation Using Satellite Observations

引用

JOURNAL OF CLIMATE 2016年第15期29卷 5447-5468页

作者： Ricko, Martina Adler, Robert F. Huffman, George J. SGT Inc 7701 Greenbelt RdSuite 400 Greenbelt MD 20770 USA Univ Maryland Earth Syst Sci Interdisciplinary Ctr College Pk MD 20742 USA NASA Goddard Space Flight Ctr Greenbelt MD USA

Climatology and variations of recent mean and intense precipitation over a near-global (50 degrees S-50 degrees N) domain on a monthly and annual time scale are analyzed. Data used to derive daily precipitation to examine the effects of spatial and temporal coverage of intense precipitation are from the current Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) 3B42 version 7 precipitation product, with high spatial and temporal resolution during 1998-2013. Intense precipitation is defined by several different parameters, such as a 95th percentile threshold of daily precipitation, a mean precipitation that exceeds that percentile, or a fixed threshold of daily precipitation value (e.g., 25 and 50 mm day(-1)). All parameters are used to identify the main characteristics of spatial and temporal variation of intense precipitation. High correlations between examined parameters are observed, especially between climatological monthly mean precipitation and intense precipitation, over both tropical land and ocean. Among the various parameters examined, the one best characterizing intense rainfall is a fraction of daily precipitation >= 25 mm day(-1), defined as a ratio between the intense precipitation above the used threshold and mean precipitation. Regions that experience an increase in mean precipitation likely experience a similar increase in intense precipitation, especially during the El Nino-Southern Oscillation (ENSO) events. Improved knowledge of this intense precipitation regime and its strong connection to mean precipitation given by the fraction parameter can be used for monitoring of intense rainfall and its intensity on a global to regional scale.

关键词： Atm/Ocean Structure/ Phenomena Extreme events Precipitation Physical Meteorology and Climatology Climatology observational techniques and algorithms Satellite observations Variability Interannual variability

来源：评论

学校读者我要写书评

暂无评论

Assimilation of Mode-S EHS Aircraft Observations in COSMO-KENDA

引用

MONTHLY WEATHER REVIEW 2016年第5期144卷 1697-1711页

作者： Lange, Heiner Janjic, Tijana Univ Munich Hans Ertel Ctr Weather Res Data Assimilat Branch Munich Germany Hans Ertel Ctr Weather Res Data Assimilat Branch Dwd Offenbach Germany

Aircraft observations of wind and temperature collected by airport surveillance radars [Mode-S Enhanced Surveillance (Mode-S EHS)] were assimilated in the Consortium for Small-Scale Modeling Kilometre-scale Ensemble Data Assimilation (COSMO-KENDA), which couples an ensemble Kalman filter to a 40-member ensemble of the convection permitting COSMO-DE model. The number of observing aircrafts in Mode-S EHS was about 15 times larger than in the AMDAR system. In the comparison of both aircraft observation systems, a similar observation error standard deviation was diagnosed for wind. For temperature, a larger error was diagnosed for Mode-S EHS. With the high density of Mode-S EHS observations, a reduction of temperature and wind error in forecasts of 1 and 3 hours was found mainly in the flight level and less near the surface. The amount of Mode-S EHS data was reduced by random thinning to test the effect of a varying observation density. With the current data assimilation setup, a saturation of the forecast error reduction was apparent when more than 50% of the Mode-S EHS data were assimilated. Forecast kinetic energy spectra indicated that the reduction in error is related to analysis updates on all scales resolved by COSMO-DE.

关键词： observational techniques and algorithms Aircraft observations Sensitivity studies Forecasting Ensembles Numerical weather prediction/forecasting Short-range prediction Models and modeling Data assimilation

来源：评论

学校读者我要写书评

暂无评论

High-Precision Measurements of the Copolar Correlation Coefficient: Non-Gaussian Errors and Retrieval of the Dispersion Parameter μ in Rainfall

引用

JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY 2016年第7期55卷 1615-1632页

作者： Keat, W. J. Westbrook, C. D. Illingworth, A. J. Univ Reading Dept Meteorol POB 243 Reading RG6 6BB Berks England

The copolar correlation coefficient rho(hv) has many applications, including hydrometeor classification, ground clutter and melting-layer identification, interpretation of ice microphysics, and the retrieval of raindrop size distributions (DSDs). However, the quantitative error estimates that are necessary if these applications are to be fully exploited are currently lacking. Previous error estimates of rho(hv) rely on knowledge of the unknown "true" rho(hv) and implicitly assume a Gaussian probability distribution function of rho(hv) samples. Frequency distributions of rho(hv) estimates are in fact shown to be highly negatively skewed. A new variable, L = 5 log(10)(1 = rho(hv)), is defined that does have Gaussian error statistics and a standard deviation depending only on the number of independent radar pulses. This is verified using observations of spherical drizzle drops, allowing, for the first time, the construction of rigorous confidence intervals in estimates of rho(hv). In addition, the manner in which the imperfect collocation of the horizontal and vertical polarization sample volumes may be accounted for is demonstrated. The possibility of using L to estimate the dispersion parameter mu in the gamma drop size distribution is investigated. Including drop oscillations is found to be essential for this application;otherwise, there could be biases in retrieved mu of up to approximately 8. Preliminary results in rainfall are presented. In a convective rain case study, the estimates presented herein show mu to be substantially larger than 0 (an exponential DSD). In this particular rain event, rain rate would be overestimated by up to 50% if a simple exponential DSD is assumed.

关键词： observational techniques and algorithms Radars/Radar observations

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：