Reports & Report Chapters

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Assessing the impact of the SCIGN radome on geodetic parameter estimates
Assessing the impact of the SCIGN radome on geodetic parameter estimates
The SCIGN radome is widely used within the geodetic community to protect GPS antennas at permanent sites from snow, debris accumulation, and vandalism. It was designed to have uniform thickness, minimizing its impact on the electrical phase center of the associated antenna. Dragert and Schmidt in their paper "The Effect of SCIGN Domes on the Vertical Phase Centre Position in Routine Processing of GPS Data" found that the radome altered the vertical coordinate solutions by 1.5 cm when used with a Dorne-Margolin(DM)/JPL Chokering antenna. This report suggested that this coordinate change was induced by a misalignment of the radome center of curvature with the mean L1/L2 electrical phase center. Ken Hudnut (the designer of the radome) confirmed this misalignment noting that the radome was designed to have a radius of curvature centered at the physical center of the DM element. There is a 3.5 cm difference between the physical position of the element and the electrical phase center; the electrical phase center is higher. Gerry Mader at the National Geodetic Survey (NGS) suggested that the NGS phase center variations (PCV) for the antenna and radome configuration should properly model this misaligment, and the radome should have no impact on geodetic parameter estimates. Dragert argues, that the empirical PCV determination technique used by the NGS does not estimate tropospheric delay parameters, inducing an error when these parameters are included in the data analysis. This report summarizes a detailed analysis of data collected at the Piñon Flat Observatory specifically collected to quantify what impact the SCIGN radomes have on geodetic parameter estimates.
Causes of solar activity
Causes of solar activity
Our nearest star, the Sun, exhibits several processes that are common to other stars: magnetic cycles, flares, prominences, and stellar winds. Recent studies suggest that many of these processes are governed by universal laws applicable to both the Sun and other stars. This solar-stellar connection can be used to extend our understanding of stellar phenomena via the study of solar processes. Thus, for example, studies of the solar dynamo will yield a better understanding of stellar dynamos: for example, what are the necessary conditions for dynamo action and how are magnetic cycles maintained? The study of the magnetic topology of solar flares and prominences will contribute significantly to the understanding of the nature of stellar flares, prominences, and winds. Herein we argue that a sustained program of long-term, high-continuity observations of the solar magnetic field is required to reach a better level of understanding of the universal processes taking place throughout the Universe.
Community input to the NRC Decadal Survey from the NCAR Workshop on Air Quality Remote Sensing From Space: Defining an optimum observing strategy
Community input to the NRC Decadal Survey from the NCAR Workshop on Air Quality Remote Sensing From Space: Defining an optimum observing strategy
The Community Workshop on Air Quality Remote Sensing from Space was held in Boulder, Colorado, February 21-23, 2006, to examine what observational characteristics are required for the successful use of satellite remote sensing to measure environmentally significant pollutant trace gases and aerosols.
Dynamos and magnetic fields of the Sun and other cool stars, and their role in the formation and evolution of stars and in the habitability of planets
Dynamos and magnetic fields of the Sun and other cool stars, and their role in the formation and evolution of stars and in the habitability of planets
A magnetic dynamo operates in all stars at least during some phases in their evolution. It regulates the formation of stars and their planetary systems, the habitability of planets, and the space weather around them. Dynamos also operate in objects including planets, accretion disks, and active galactic nuclei. Although we know that flows in rotating systems are essential to such dynamos, there is no comprehensive dynamo theory from which we can derive the strength, the patterns, or the temporal behavior of stellar magnetic fields.
Emissions of short-lived climate forcers in an Arctic context
Emissions of short-lived climate forcers in an Arctic context
This report provides the accessible scientific basis and validation for the statements and recommendations made in the Summary for Policy-makers: Arctic Climate Issues 2015 report that was delivered to Arctic Council Ministers at their meeting in Iqaluit, Canada in April 2015. It is also the basis for a related AMAP State of the Arctic Environment report Arctic Climate Issues 2015: Overview. It includes extensive background data and references to the scientific literature, and details the sources for figures reproduced in the overview report. Whereas the Summary for Policy-makers report contains recommendations that focus mainly on policy-relevant actions concerned with addressing short-lived climate forcers, the conclusions and recommendations presented in this report also cover issues of a more scientific nature, such as proposals for filling gaps in knowledge, and recommendations relevant to future monitoring and research work.
Evaluating global warming potentials with historical temperature: An application of ACC2 inversion
Evaluating global warming potentials with historical temperature: An application of ACC2 inversion
Global Warming Potentials (GWPs) are evaluated as historical temperature proxies by applying them to convert historical CH₄ and N₂O emissions to equivalent CO₂ emissions. Our GWP analysis is based on the inverse estimation for the Aggregated Carbon Cycle, Atmospheric Cycle, and Climate Model (ACC2). It was found that, for both CH₄ and N₂O, indices higher than the Kyoto GWPs (100-year time horizon) would reproduce better the historical temperature. The CH₄ GWP provides a best fit to the historical temperature with the time horizon of 44 years. However, the N₂O GWP does not approximate the historical temperature with any time horizon. We introduce a new exchange metric, TEMperature Proxy index (TEMP) that is defined so that it provides a best fit to the temperature projection of a given period. By comparing the GWPs and TEMPs, we found that the inability of the N₂O GWP to reproduce the historical temperature is caused by the fact that the GWP calculation methodology in IPCC gives coarse treatments to the background system dynamics and uncertain parameter estimations. Furthermore, our TEMP calculations demonstrate that indices have to be progressively updated upon the acquisition of new measurements and/or the advancement of our understanding on the Earth system processes.
FIP Severity Technical Document
FIP Severity Technical Document
This was a technical report to the FAA, who sponsored research in this area. It was presented to fulfill requirements of the Aviation Weather Technology Transfer Technical Review Panel.
Flight testing of a SABIR arm for use in air sampling
Flight testing of a SABIR arm for use in air sampling
A modified airborne research pod was flown on the NSF/NCAR C130 using a SABIR arm installation. Inlets for air sampling were installed on the pod and connected to air quality instrumentation for Condensation Nuclei, Ozone, Carbon Monoxide, Methane, Carbon Dioxide and water vapor. These locations were compared with traditional sampling locations on the C130 to determine if there was evidence for contamination (e.g. from cabin air or engine exhaust) at the pod location. Testing in various aircraft configurations, altitudes, airspeeds, and flight conditions (changing attack and sideslip) were conducted to determine if contamination or other operational concerns arose. Initial analysis of the data and comparison with the other sampling locations has not found evidence for significant contamination at the pod sampling location. The most serious concern arose during testing with the wheels extended, which produced extensive turbulence at the pod location which rendered that configuration unsuitable. For future installation on LC-130 (ski-equipped) aircraft, we recommend similar testing be conducted, because the skis may produce a turbulence effect which we were not able to simulate.

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