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At least 73 records · Page 4

The Apollo 17 station 7 boulder - Summary of study by the International Consortium

A systematic interdisciplinary study of the Apollo 17 station 7 boulder, from the foot of the North Massif at Taurus-Littrow, is described. The astronauts observed four lithologies: a large white clast represented by 77215, cut by dark dikelets (77075) and enclosed in blue-gray breccia (77115); the assemblage of these three rock types is in turn surrounded by green-gray breccia (77135). The history of the station 7 boulder, as construed from the results of the consortium study, is presented.

Minkin, J. A.↗

Measurements of plasmaspheric columnar electron content from ATS6 at Boulder, CO and Lorman, MS from December, 1976 to May, 1978

TEC measurements were made of the ionosphere and plasmasphere at Boulder, CO and Lorman, MS using the ATS-6 radio beacon, and winter diurnal behavior is compared for three time periods over North American and Europe. Analyses indicate that during the winter of 1976-1977 at Lorman, and the winter of 1977-1978 at Boulder, the plasmasphere content had no diurnal variation, although in the winter of 1974-1975 the peak occurred at night. Differences in diurnal behavior over North America and Europe are explained by a combination of plasma flow in and out of local and conjugate ionospheres. The difference appears to be temporal rather than spatial, thus, the cross-L drift of plasma tubes under the influence of electric fields is suggested to be an influence on the diurnal variation of the plasmaspheric columnar electron content.

Davies, K.↗

Mars Exploration Rover Landing Site Boulder Fields

As an aid in constraining the rock size-frequency distributions at the Mars Exploration Rover (MER) landing sites, Mars Orbiter Camera (MOC) images of all potential MER landing sites were systematically searched for boulder fields. Low-Sun angle MOC images can be used to identify boulders larger than 1.5 m diameter, which can be used to determine the shape of the rock size-frequency distributions. These distributions can be compared with the rock size-frequency distributions measured at the Viking and Mars Pathfinder landing sites to better quantify potentially hazardous rocks at the MER landing sites.

Schroeder, R. D.↗

Inferred Lunar Boulder Distributions at Decimeter Scales

Block size distributions of impact deposits on the Moon are diagnostic of the impact process and environmental effects, such as target lithology and weathering. Block size distributions are also important factors in trafficability, habitability, and possibly the identification of indigenous resources. Lunar block sizes have been investigated for many years for many purposes [e.g., 1-3]. An unresolved issue is the extent to which lunar block size distributions can be extrapolated to scales smaller than limits of resolution of direct measurement. This would seem to be a straightforward statistical application, but it is complicated by two issues. First, the cumulative size frequency distribution of observable boulders rolls over due to resolution limitations at the small end. Second, statistical regression provides the best fit only around the centroid of the data [4]. Confidence and prediction limits splay away from the best fit at the endpoints resulting in inferences in the boulder density at the CPR scale that can differ by many orders of magnitude [4]. These issues were originally investigated by Cintala and McBride [2] using Surveyor data. The objective of this study was to determine whether the measured block size distributions from Lunar Reconnaissance Orbiter Camera - Narrow Angle Camera (LROC-NAC) images (m-scale resolution) can be used to infer the block size distribution at length scales comparable to Mini-RF Circular Polarization Ratio (CPR) scales, nominally taken as 10 cm. This would set the stage for assessing correlations of inferred block size distributions with CPR returns [6].

Baloga, S. M.↗

Discrete Element Method Simulation of a Boulder Extraction From an Asteroid

The force required to pull 7t and 40t polyhedral boulders from the surface of an asteroid is simulated using the discrete element method considering the effects of microgravity, regolith cohesion and boulder acceleration. The connection between particle surface energy and regolith cohesion is estimated by simulating a cohesion sample tearing test. An optimal constant acceleration is found where the peak net force from inertia and cohesion is a minimum. Peak pulling forces can be further reduced by using linear and quadratic acceleration functions with up to a 40% reduction in force for quadratic acceleration.

Kulchitsky, Anton K.↗

Boulder County Disasters: Mapping Forest Carbon Stocks to Understand Carbon Implications of Treatment and Wildfire

In recent years, record-breaking wildfire activities in the western US illustrate the need for fire mitigation efforts, such as forest fuels reduction treatments. Forests serve as crucial carbon sinks that combat the increasing effects of climate change while fuels reduction treatments may remove carbon from forested systems. As a result, forest managers need to find a balance between fire mitigation and carbon preservation. This project partnered with Boulder County Parks and Open Space (BCPOS) and the University of Colorado, Denver to investigate the 2020 Cal-Wood fire in Boulder County, Colorado. Using remote sensing data from Landsat 8 OLI, SRTM, Sentinel-2 MSI, and LiDAR, we mapped post-fire forest carbon pools and compared these values with values derived from measurements from plots on the ground. Results indicate that the correlations are R2=0.76 for aboveground live carbon, R2=0.44 for standing carbon, and R2=0.43 for aboveground dead carbon (R2=0.43), and R2=0.35 for total carbon (R2=0.35). Additionally, 38.5% of total carbon was stored in dead carbon and 14.4% was stored in live carbon. We next compared the post-fire pools between treated and untreated areas. Our analysis suggests fuels reduction treatments did not reduce carbon loss in the presence of wildfire enough to clearly distinguish the post-fire carbon in the treated and untreated areas. However, our final carbon maps still provide BCPOS and researchers with an opportunity to explore carbon estimation models based on remotely sensed data as well as a framework to evaluate fuels reduction treatment effectiveness and impact on forest carbon stocks for future wildfire events.

Sarah Hettema↗

On Dynamical Impacts on Stratospheric Water Vapor Trends Above Boulder, Colorado

Long-term stratospheric water vapor (SWV) trends above Boulder, CO, (40°N, 255°E) are generally positive and slightly larger than those for zonal average SWV. This study finds a slight enhancement for SWV at 31.6 hPa above Boulder from middle February through March 1979, as seen in the satellite dataset from the LIMS instrument. That excess of SWV correlates well with air in the polar vortex that underwent an elongation and splitting in middle February following a final stratospheric warming event. Zonal wave-2 events tend to occur in late winter, but not every year. Such aperiodic variations in data time series of SWV may affect the fitting of its linear trend term.

Ellis Remsberg↗

On Dynamical Impacts on Stratospheric Water Vapor Trends Above Boulder, Colorado

Long-term stratospheric water vapor (SWV) trends above Boulder, CO, (40°N, 255°E) are generally positive and slightly larger than those for zonal average SWV. This study finds a slight enhancement for SWV at 31.6 hPa above Boulder from middle February through March 1979, as seen in the satellite dataset from the LIMS instrument. That excess of SWV correlates well with air in the polar vortex that underwent an elongation and splitting in middle February following a final stratospheric warming event. Zonal wave-2 events tend to occur in late winter, but not every year. Such aperiodic variations in data time series of SWV may affect the fitting of its linear trend term.

Ellis Remsberg↗

Mapping Forest Carbon Stocks to Understand Carbon Implications of Treatment on Wildfire for the Calwood Fire, Boulder County Colorado

Recent, record-breaking wildfire activity in the western U.S. illustrates the need for fire mitigation, such as forest fuels reduction treatments. Forests serve as crucial carbon sinks that combat the increasing effects of climate change, but fuels reduction treatments may remove carbon from forested systems. As a result, forest managers need to find a balance between fire mitigation and carbon preservation. This project partnered with Boulder County Parks and Open Space (BCPOS) and the University of Colorado, Denver to investigate the 2020 Cal-Wood fire in Boulder County, Colorado. Using remote sensing data from Landsat 8 Operational Land Imager, Shuttle Radar Topography Mission, Sentinel-2 MultiSpectral Imagery, and LiDAR, we mapped post-fire forest carbon pools and compared these values with values derived from field measurements. The analysis suggested that fuels reduction treatments did not reduce carbon loss in the presence of wildfire enough to clearly distinguish post-fire carbon between treated and untreated areas. However, the final carbon maps provide BCPOS and researchers with an opportunity to explore carbon estimation models based on remote sensing data as well as a framework to evaluate fuels reduction treatment effectiveness and impact on forest carbon stocks for future wildfire events.

Sarah Hettema↗

An Assessment of Stratospheric Water Vapor Trends and Variations Above the Boulder Region

This study analyzes time series of stratospheric water vapor (SWV) data at 30 hPa, based on frost-point hygrometer (FPH) measurements at Boulder, CO (40°N, 255°E), and on sets of HALOE scans above that region for 1993 through 2005; their differing trends agree with previously published findings. Yet, there is an apparent switch over in 2002 from positive to negative trends in the HALOE time series, and that change follows the episodic decrease of tropical, lower stratospheric SWV in early 2001. The HALOE data points only resolve medium to large scale spatial variations, as they are based on an average of four or more limb scans within a latitude/longitude sector near Boulder. The FPH time series do not indicate a similar change of trend in 2002, although its time series points have variations about the mean that are twice as large as those from HALOE. The FPH soundings are sensitive to variations from all spatial scales, however, including the effects of a local vertical mixing of the air due to gravity waves. The vertical gradient SWV mixing ratio with altitude is positive at 30 hPa. There is also a positive trend in methane and its conversion to water vapor during this time that may explain a slightly larger SWV trend from the local FPH data than from the HALOE data. The Nimbus 7 LIMS experiment provides daily SWV plots at medium to large scales during the dynamically active, winter and springtime periods, for assessing the effects of meridional transport of SWV from its source regions. There is transport of high SWV from polar regions and of lower SWV from the subtropics at those times. SWV variations and trends from both the FPH and HALOE time series are reasonable and in accord with the spatial scales that they observed.

Ellis Remsberg↗

Existing Whole-House Solutions Case Study: Evaluation of a Multifamily Retrofit in Climate Zone 5, Boulder, Colorado

In 2009, a 37-unit apartment complex located in Boulder, Colorado, underwent an energy retrofit to comply with Boulder SmartRegs Ordinance, a mandate that requires all rental properties to meet certain energy efficiency standards by 2018. The Consortium of Advanced Residential Buildings (CARB), a U.S. Department of Energy Building America team, worked with city planners and building owners to evaluate this program and recently completed a case study evaluating the effectiveness of a collection of retrofit measures.

apartments↗

Boulder Wind Power Advanced Gearless Drivetrain: Cooperative Research and Development (Final Report)

The Boulder Wind Power (BWP) Advanced Gearless Drivetrain Project explored the application of BWP's innovative, axial-gap, air-core, permanent-magnet direct-drive generator in offshore wind turbines. The objective of this CRADA is to assess the benefits that result from reduced towerhead mass of BWP's technology when used in 6 MW offshore turbines installed on a monopile or a floating spar foundation.

17 WIND ENERGY↗

Solar Row Zero Energy Townhomes - Boulder, CO

Wonderland Development has constructed a new "near zero energy" row home design in North Boulder consisting of 9 units: one 5-plex and two duplexes. NREL has performed short-term tests and installed long-term monitoring equipment in three of these units. Two of these units used a solar thermal combi system with a boiler for radiant space heating and water heating and mini-split system for space conditioning. The third unit used a high efficiency tank water heater for space heating. In addition to studying the overall performance of the homes, one unit was used for a detailed study on hot water draws at each fixture. Several reports and presentations were produced on this project, however, due to shifting funding and staffing priorities, a comprehensive final report for this project was never completed. This dataset contains a wealth of raw and analyzed data and several unpublished reports.

Array↗

Preliminary data on boulders at station 6, Apollo 17 landing site

A cluster of boulders at Station 6 (Apollo 17 landing site) consists of breccias derived from the North Massif. Three preliminary lithologic units were established, on the basis of photogeologic interpretations; all lithologies identified photogeologically were sampled. Breccia clasts and matrices studied petrographically and chemically fall into two groups by modal mineralogy: (1) low-K Fra Mauro or high basalt composition, consisting of 50-60% modal feldspar, approximately 45% orthopyroxene and 1-7% Fe-Ti oxide; (2) clasts consisting of highland basalt composition, consisting of 70% feldspar, 30% orthopyroxene and olivine and a trace of Fe-Ti oxide.

Heiken, G. H.↗