Search

The San Joaquin Valley (SJV) experiences some of the worst ozone air quality in the US, frequently exceeding the California 8 h standard of 70.4 ppb. To improve our understanding of trends in the number of ozone violations in the SJV, we analyze observed relationships between organic reactivity, nitrogen oxides (NO[subscript x]), and daily maximum temperature in the southern SJV using measurements made as part of California at the Nexus of Air Quality and Climate Change in 2010 (CalNex-SJV). We find the daytime speciated organic reactivity with respect to OH during CalNex-SJV has a temperature-independent portion with molecules typically associated with motor vehicles being the major component. At high temperatures, characteristic of days with high ozone, the largest portion of the total organic reactivity increases exponentially with temperature and is dominated by small, oxygenated organics and molecules that are unidentified. We use this simple temperature classification to consider changes in organic emissions over the last and next decade. With the CalNex-SJV observations as constraints, we examine the sensitivity of ozone production (PO[subscript 3]) to future NO[subscript x] and organic reactivity controls. We find that PO[subscript 3] is NO[subscript x]-limited at all temperatures on weekends and on weekdays when daily maximum temperatures are greater than 29 °C. As a consequence, NO[subscript x] reductions are the most effective control option for reducing the frequency of future ozone violations in the southern SJV., California Environmental Protection Agency. Air Resources Board (Contract CARB 08-316), United States. National Aeronautics and Space Administration (Grant NNX10AR36G)

We present a new instrument, Hoxotope, for the in situ measurement of H2O and its heavy deuterium isotopologue (HDO) in the upper troposphere and lower stratosphere aboard the NASA WB-57. Sensitive measurements of deltaD are accomplished through the vacuum UV photolysis of water followed by laser-induced fluorescence detection of the resultant OH and OD photofragments. The photolysis laser-induced fluorescence technique can obtain S/N>20 for 1 ppbv HDO and S/N>30 for 5 ppmv H2O for 10 s data, providing the sensitivity required for deltaD measurements in the tropopause region. The technique responds rapidly to changing water concentrations due to its inherently small sampling volume, augmented by steps taken to minimize water uptake on instrument plumbing. Data from the summer 2005 Aura Validation Experiment Water Isotope Intercomparison Flights (AVE-WIIF) out of Houston, TX show agreement for H2O between Hoxotope and the Harvard water vapor instrument and for HDO between Hoxotope and the Harvard ICOS water isotope instrument, to within stated instrument uncertainties. The successful intercomparison validates Hoxotope as a credible source of deltaD data in the upper troposphere and lower stratosphere.

We present a new instrument, Hoxotope, for the in situ measurement of H2O and its heavy deuterium isotopologue (HDO) in the upper troposphere and lower stratosphere aboard the NASA WB-57. Sensitive measurements of deltaD are accomplished through the vacuum UV photolysis of water followed by laser-induced fluorescence detection of the resultant OH and OD photofragments. The photolysis laser-induced fluorescence technique can obtain S/N>20 for 1 ppbv HDO and S/N>30 for 5 ppmv H2O for 10 s data, providing the sensitivity required for deltaD measurements in the tropopause region. The technique responds rapidly to changing water concentrations due to its inherently small sampling volume, augmented by steps taken to minimize water uptake on instrument plumbing. Data from the summer 2005 Aura Validation Experiment Water Isotope Intercomparison Flights (AVE-WIIF) out of Houston, TX show agreement for H2O between Hoxotope and the Harvard water vapor instrument and for HDO between Hoxotope and the Harvard ICOS water isotope instrument, to within stated instrument uncertainties. The successful intercomparison validates Hoxotope as a credible source of deltaD data in the upper troposphere and lower stratosphere.

This current report from the US Department of Agriculture Forest Service, Pacific Northwest Research Station evaluates the genetic resource status of several Pacific Northwest timber species. The 60-page report can be viewed using Adobe Acrobat Reader. The report finds that species like ponderosa pine, noble fir, and western hemlock have "extensive genetic resources in ex situ forms," while the resources for red cedar are more limited.

This current report from the US Department of Agriculture Forest Service, Pacific Northwest Research Station evaluates the genetic resource status of several Pacific Northwest timber species. The 60-page report can be viewed using Adobe Acrobat Reader. The report finds that species like ponderosa pine, noble fir, and western hemlock have "extensive genetic resources in ex situ forms," while the resources for red cedar are more limited.

This current report from the US Department of Agriculture Forest Service, Pacific Northwest Research Station evaluates the genetic resource status of several Pacific Northwest timber species. The 60-page report can be viewed using Adobe Acrobat Reader. The report finds that species like ponderosa pine, noble fir, and western hemlock have "extensive genetic resources in ex situ forms," while the resources for red cedar are more limited.

The Phase III, Volume I, report presents the results of a study program on Category III airborne All Weather Landing Systems. The primary program effort was directed toward the evaluation of reliability, availability, safety, and human factors for airborne systems ranging from Simplex to multi-channel Fail Operative configurations. Included in the report are mathematical models depicting reliability and safety as a function of system configuration and operating parameters. From the Reliability models, a computerized program is generated, presenting the reliability, availability, and safety of the various systems being considered for Category III landings. Also, as part of this program, a Human Factors error analysis was conducted to determine the probability of human error, based on the tasks required to perform a Category III landing. Using the results of the Human Error analysis and the Airborne System Reliability analysis, a safety model was derived that presents the probability of occurrence of a hazardous event. As a result of these studies, data was generated to allow comparison of systems with respect to reliability and safety, and to outline potential problem areas. A Volume II of this report has been published under a separate cover. Volume II contains supplementary data, presented in the form of appendices, developed in support of the analysis presented herein., See also AD-655 241, Volume 2.

The primary program effort was directed toward a quantitative evaluation of reliability, availability, safety and human factors for airborne systems. Since a number of considerations associated with Category III landing problems presently defy quantification, an appendix has been developed to investigate in general these considerations. The reliability analysis presented in Volume I has required a large and varied number of calculations. Appendices have been developed to present examples of the manner in which these calculations were effected. Also presented is a discussion of a proposed two channel system exhibiting a fail operative capability, which is contrary to the fail passive characteristics of a two channel system assumed in Volume I. During this program, a considerable amount of research was conducted to provide a basis for the development of a quantiative human error prediction procedure. The results of this research is presented in appendices covering general human factors considerations associated with Category III systems and an analysis of accident data which was conducted to investigate human error characteristics of aircraft accidents., See also AD-655 240, Volume 1.