Forcing Mechanisms for Washoe Zephyr—A Daytime Downslope Wind System in the Lee of the Sierra Nevada

2008 ◽  
Vol 47 (1) ◽  
pp. 339-350 ◽  
Author(s):  
Shiyuan Zhong ◽  
Ju Li ◽  
Craig B. Clements ◽  
Stephan F. J. De Wekker ◽  
Xindi Bian
Keyword(s):  
Pressure Gradient ◽  
Sierra Nevada ◽  
Great Basin ◽  
Regional Scale ◽  
Surface Wind ◽  
Formation Mechanisms ◽  
Climate Data ◽  
Local Pressure ◽  
Interesting Phenomenon ◽  
Downslope Wind

Abstract This paper investigates the formation mechanisms for a local wind phenomenon known as Washoe Zephyr that occurs frequently in the lee of the Sierra Nevada. Unlike the typical thermally driven slope flows with upslope wind during daytime and downslope at night, the Washoe Zephyr winds blow down the lee slopes of the Sierra Nevada in the afternoon against the local pressure gradient. Long-term hourly surface wind data from several stations on the eastern slope of the Sierra Nevada and rawinsonde sounding data in the region are analyzed and numerical simulations are performed to test the suggested hypotheses on the formation mechanisms for this interesting phenomenon. The results from surface and upper-air climate data analyses and numerical modeling indicate that the Washoe Zephyr is primarily a result of a regional-scale pressure gradient that develops because of asymmetric heating of the atmosphere between the western side of the Sierra Nevada and the elevated, semiarid central Nevada and Great Basin on the eastern side of the Sierra Nevada. The frequent influence of the Pacific high on California in the summer season helps to enhance this pressure gradient and therefore strengthen the flow. Westerly synoptic-scale winds over the Sierra Nevada and the associated downward momentum transfer are not necessary for its development, but strong westerly winds aloft work in concert with the regional-scale pressure gradient to produce the strongest Washoe Zephyr events.

An Attack on the Contamination Problem in the Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 368-368
Author(s):  
J. J. Kelsch ◽  
A. Holtz
Keyword(s):  
Electron Microscope ◽  
Pressure Gradient ◽  
Ionization Potential ◽  
Simple Solution ◽  
Specimen Surface ◽  
Contamination Rate ◽  
Local Pressure ◽  
High Ionization ◽  
Hydrocarbon Molecules ◽  
Contamination Problem

A simple solution to the serious problem of specimen contamination in the electron microscope is presented. This is accomplished by the introduction of clean helium into the vacuum exactly at the specimen position. The local pressure gradient thus established inhibits the migration of hydrocarbon molecules to the specimen surface. The high ionization potential of He permits the use of relatively large volumes of the gas, without interfering with gun stability. The contamination rate is reduced on metal samples by a factor of 10.

scholarly journals Error Correction of Multi-Source Weighted-Ensemble Precipitation (MSWEP) over the Lancang-Mekong River Basin

2021 ◽  
Vol 13 (2) ◽  
pp. 312
Author(s):  
Xiongpeng Tang ◽  
Jianyun Zhang ◽  
Guoqing Wang ◽  
Gebdang Biangbalbe Ruben ◽  
Zhenxin Bao ◽  
...  
Keyword(s):  
Error Correction ◽  
River Basin ◽  
Regional Scale ◽  
Mekong River ◽  
Precipitation Data ◽  
Climate Data ◽  
Hydrological Simulation ◽  
Mekong River Basin ◽  
Precipitation Estimation ◽  
Simulation Results

The demand for accurate long-term precipitation data is increasing, especially in the Lancang-Mekong River Basin (LMRB), where ground-based data are mostly unavailable and inaccessible in a timely manner. Remote sensing and reanalysis quantitative precipitation products provide unprecedented observations to support water-related research, but these products are inevitably subject to errors. In this study, we propose a novel error correction framework that combines products from various institutions. The NASA Modern-Era Retrospective Analysis for Research and Applications (AgMERRA), the Asian Precipitation Highly-Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE), the Climate Hazards group InfraRed Precipitation with Stations (CHIRPS), the Multi-Source Weighted-Ensemble Precipitation Version 1.0 (MSWEP), and the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Records (PERSIANN) were used. Ground-based precipitation data from 1998 to 2007 were used to select precipitation products for correction, and the remaining 1979–1997 and 2008–2014 observe data were used for validation. The resulting precipitation products MSWEP-QM derived from quantile mapping (QM) and MSWEP-LS derived from linear scaling (LS) are evaluated by statistical indicators and hydrological simulation across the LMRB. Results show that the MSWEP-QM and MSWEP-LS can better capture major annual precipitation centers, have excellent simulation results, and reduce the mean BIAS and mean absolute BIAS at most gauges across the LMRB. The two corrected products presented in this study constitute improved climatological precipitation data sources, both time and space, outperforming the five raw gridded precipitation products. Among the two corrected products, in terms of mean BIAS, MSWEP-LS was slightly better than MSWEP-QM at grid-scale, point scale, and regional scale, and it also had better simulation results at all stations except Strung Treng. During the validation period, the average absolute value BIAS of MSWEP-LS and MSWEP-QM decreased by 3.51% and 3.4%, respectively. Therefore, we recommend that MSWEP-LS be used for water-related scientific research in the LMRB.

Sierra Nevada-Great Basin boundary zone: Earthquake hazard related to structure, active tectonic processes, and anomalous patterns of earthquake occurrence

1980 ◽  
Vol 70 (5) ◽  
pp. 1557-1572
Author(s):  
J. D. VanWormer ◽  
Alan S. Ryall
Keyword(s):  
Sierra Nevada ◽  
Great Basin ◽  
Temporal Variations ◽  
Mono Lake ◽  
Local Network ◽  
Low Velocity ◽  
Owens Valley ◽  
Walker Lake ◽  
Fault Plane Solutions ◽  
The North

abstract Precise epicentral determinations based on local network recordings are compared with mapped faults and volcanic features in the western Great Basin. This region is structurally and seismically complex, and seismogenic processes vary within it. In the area north of the rupture zone of the 1872 Owens Valley earthquake, dispersed clusters of epicenters agree with a shatter zone of faults that extend the 1872 breaks to the north and northwest. An area of frequent earthquake swarms east of Mono Lake is characterized by northeast-striking faults and a crustal low-velocity zone; seismicity in this area appears to be related to volcanic processes that produced thick Pliocene basalt flows in the Adobe Hills and minor historic activity in Mono Lake. In the Garfield Hills between Walker Lake and the Excelsior Mountains, there is some clustering of epicenters along a north-trending zone that does not correlate with major Cenozoic structures. In an area west of Walker Lake, low seismicity supports a previous suggestion by Gilbert and Reynolds (1973) that deformation in that area has been primarily by folding and not by faulting. To the north, clusters of earthquakes are observed at both ends of a 70-km-long fault zone that forms the eastern boundary of the Sierra Nevada from Markleeville to Reno. Clusters of events also appear at both ends of the Dog Valley Fault in the Sierra west of Reno, and at Virginia City to the east. Fault-plane solutions for the belt in which major earthquakes have occurred in Nevada during the historic period (from Pleasant Valley in the north to the Excelsior Mountains on the California-Nevada Border) correspond to normaloblique slip and are similar to that found by Romney (1957) for the 1954 Fairview Peak shock. However, mechanisms of recent moderate earthquakes within the SNGBZ are related to right- or left-lateral slip, respectively, on nearly vertical, northwest-, or northeast-striking planes. These mechanisms are explained by a block faulting model of the SNGBZ in which the main fault segments trend north, have normal-oblique slip, and are offset or terminated by northwest-trending strike-slip faults. This is supported by the observation that seismicity during the period of observation has been concentrated at places where major faults terminate or intersect. Anomalous temporal variations, consisting of a general decrease in seismicity in the southern part of the SNGBZ from October 1977 to September 1978, followed by a burst of moderate earthquakes that has continued for more than 18 months, is suggestive of a pattern that several authors have identified as precursory to large earthquakes. The 1977 to 1979 variations are particularly noteworthy because they occurred over the entire SNGBZ, indicating a regional rather than local cause for the observed changes.

scholarly journals Fundamental Climate Data Records of Microwave Brightness Temperatures

2018 ◽  
Vol 10 (8) ◽  
pp. 1306 ◽  
Author(s):  
Wesley Berg ◽  
Rachael Kroodsma ◽  
Christian Kummerow ◽  
Darren McKague
Keyword(s):  
Land Surface ◽  
Surface Wind ◽  
Precipitable Water ◽  
Original Data ◽  
Climate Data ◽  
Sea Ice Extent ◽  
Brightness Temperatures ◽  
Precipitation Total ◽  
Data Record ◽  
Microwave Imager

An intercalibrated Fundamental Climate Data Record (FCDR) of brightness temperatures (Tb) has been developed using data from a total of 14 research and operational conical-scanning microwave imagers. This dataset provides a consistent 30+ year data record of global observations that is well suited for retrieving estimates of precipitation, total precipitable water, cloud liquid water, ocean surface wind speed, sea ice extent and concentration, snow cover, soil moisture, and land surface emissivity. An initial FCDR was developed for a series of ten Special Sensor Microwave/Imager (SSM/I) and Special Sensor Microwave Imager Sounder (SSMIS) instruments on board the Defense Meteorological Satellite Program spacecraft. An updated version of this dataset, including additional NASA and Japanese sensors, has been developed as part of the Global Precipitation Measurement (GPM) mission. The FCDR development efforts involved quality control of the original data, geolocation corrections, calibration corrections to account for cross-track and time-dependent calibration errors, and intercalibration to ensure consistency with the calibration reference. Both the initial SSMI(S) and subsequent GPM Level 1C FCDR datasets are documented, updated in near real-time, and publicly distributed.

scholarly journals The Synoptic and Mesoscale Evolution Accompanying the 2018 Camp Fire of Northern California

2020 ◽  
pp. 1-45
Author(s):  
Clifford F. Mass ◽  
David Ovens
Keyword(s):  
Sierra Nevada ◽  
Northern California ◽  
Wind Event ◽  
Downslope Wind

CapsuleThe Camp Fire of November 2018 was associated with a strong, well-forecast, downslope wind event over the western slopes of the Sierra Nevada near Paradise, California.

scholarly journals Climate, snow, and soil moisture data set for the Tuolumne and Merced river watersheds, California, USA

2019 ◽  
Vol 11 (1) ◽  
pp. 101-110 ◽  
Author(s):  
James W. Roche ◽  
Robert Rice ◽  
Xiande Meng ◽  
Daniel R. Cayan ◽  
Michael D. Dettinger ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Sierra Nevada ◽  
Land Surface ◽  
Forest Canopy ◽  
Snow Water Equivalent ◽  
Process Models ◽  
Series Data ◽  
Climate Data ◽  
Data Set ◽  
Data Repositories

Abstract. We present hourly climate data to force land surface process models and assessments over the Merced and Tuolumne watersheds in the Sierra Nevada, California, for the water year 2010–2014 period. Climate data (38 stations) include temperature and humidity (23), precipitation (13), solar radiation (8), and wind speed and direction (8), spanning an elevation range of 333 to 2987 m. Each data set contains raw data as obtained from the source (Level 0), data that are serially continuous with noise and nonphysical points removed (Level 1), and, where possible, data that are gap filled using linear interpolation or regression with a nearby station record (Level 2). All stations chosen for this data set were known or documented to be regularly maintained and components checked and calibrated during the period. Additional time-series data included are available snow water equivalent records from automated stations (8) and manual snow courses (22), as well as distributed snow depth and co-located soil moisture measurements (2–6) from four locations spanning the rain–snow transition zone in the center of the domain. Spatial data layers pertinent to snowpack modeling in this data set are basin polygons and 100 m resolution rasters of elevation, vegetation type, forest canopy cover, tree height, transmissivity, and extinction coefficient. All data are available from online data repositories (https://doi.org/10.6071/M3FH3D).

scholarly journals Assimilated diet patterns of American black bears in the Sierra Nevada and western Great Basin, Nevada, USA

Ursus ◽  
2020 ◽  
Vol 2019 (30e3) ◽  
pp. 40
Author(s):  
Jennapher Teunissen van Manen ◽  
Carl W. Lackey ◽  
Jon P. Beckmann ◽  
Lisa I. Muller ◽  
Zheng-Hua Li
Keyword(s):  
Sierra Nevada ◽  
Great Basin ◽  
Black Bears ◽  
Diet Patterns ◽  
American Black ◽  
American Black Bears ◽  
Assimilated Diet

Forecasting long-term shoreline evolution in highly antrhopized coastal areas

2021 ◽  
Author(s):  
Moisés Álvarez-Cuesta ◽  
Alexandra Toimil ◽  
Iñigo J. Losada
Keyword(s):  
Climate Models ◽  
Regional Scale ◽  
Mediterranean Coast ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Coastal Zones ◽  
Climate Data ◽  
Shoreline Evolution ◽  
Automated Technique

<p>A new numerical model for addressing long-term coastline evolution on a local to regional scale on highly anthropized coasts is presented. The model, named IH-LANS (Long-term ANthropized coastlines Simulation tool), is validated over the period 1990-2020 and applied to obtain an ensemble of end-of-century shoreline evolutions. IH-LANS combines a hybrid (statistical-numerical) deep-water propagation module and a shoreline evolution model. Longshore and cross-shore processes are integrated together with the effects of man-made interventions. For the ease of calibration, an automated technique is implemented to assimilate observations. The model is applied to a highly anthropized 40 km stretch located along the Spanish Mediterranean coast. High space-time resolution climate data and satellite-derived shorelines are used to drive IH-LANS. Observed shoreline evolution (<10 meters of root mean square error, RMSE) is successfully represented while accounting for the effects of nourishments and the construction and removal of groynes, seawalls and breakwaters over time. Then, in order to drive the ensemble of end-of-century shoreline evolutions, wave and water level projections downscaled from different climate models for various emissions scenarios are employed to force the calibrated model. From the forecasted shoreline time-series, information from multiple time-scales is unraveled yielding valuable information for coastal planners. The efficiency and accuracy of the model make IH-LANS a powerful tool for management and climate change adaptation in coastal zones.</p>

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