166 research outputs found
Resource allocation for wildland fire suppression planning using a stochastic program
2011 Fall.Includes bibliographical references.Resource allocation for wildland fire suppression problems, referred to here as Fire-S problems, have been studied for over a century. Not only have the many variants of the base Fire-S problem made it such a durable one to study, but advances in suppression technology and our ever-expanding knowledge of and experience with wildland fire behavior have required almost constant reformulations that introduce new techniques. Lately, there has been a strong push towards randomized or stochastic treatments because of their appeal to fire managers as planning tools. A multistage stochastic program with variable recourse is proposed and explored in this paper as an answer to a single-fire planning version of the Fire-S problem. The Fire-S stochastic program is discretized for implementation according to scenario trees, which this paper supports as a highly useful tool in the stochastic context. Our Fire-S model has a high level of complexity and is parameterized with a complicated hierarchical cluster analysis of historical weather data. The cluster analysis has some incredibly interesting features and stands alone as an interesting technique apart from its application as a parameterization tool in this paper. We critique the planning model in terms of its complexity and options for an operational version are discussed. Although we assume no interaction between fire spread and suppression resources, the possibility of incorporating such an interaction to move towards an operational, stochastic model is outlined. A suppression budget analysis is performed and the familiar "production function" fire suppression curve is created, which strongly indicates the Fire-S model performs in accordance with fire economic theory as well as its deterministic counterparts. Overall, this exploratory study demonstrates a promising future for the existence of tractable stochastic solutions to all variants of Fire-S problems
Ship-board report on atmospheric CO2 concentrations recorded on continuous from Mediterranean sea to Antarctica
We present the results obtained from continuous measurements
performed during two cruises with hemispherical courses. In this way, we obtained the latitudinal trend of CO2 in continuity of space and time along two hemispheric courses in 1994-95 and 1996-97 from Europe to Antarctica. The results are compared with measurements from the National Oceanic and Atmospheric Administration (NOAA) Climate Monitoring and Diagnostic Laboratory (CMDL) cooperative air
sampling network. The fitting of data recorded on board with the historical data sets recorded at Palmer Station is also presented, highlighting the current annual increase in atmospheric CO2 concentrations
Trace gases and CO2 isotope records from cabo de rama, India
Concentrations of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), nitrous oxide (N2O) and hydrogen (H2), and the stable carbon (δ 13C-CO2) and oxygen (δ 18O-CO2) isotopic composition of CO2 have been measured in air samples collected from Cabo de Rama (CRI), India, for the period 1993-2002. The observations show clear signatures of Northern and Southern Hemispheric (NH and SH) air masses, mixed with their regional fluxes and chemical loss mechanisms, resulting in complex seasonal variation of these gases. The CRI measurements are compared with remote marine sites at Seychelles and Mauna Loa. Simulations of two major anthropogenic greenhouse gases (CO2 and CH4) concentrations using a chemistry-transport model for the CRI site suggest that globally optimized fluxes can produce results comparable to the observations. We discuss that CRI observations have provided critical guidance in optimizing the fluxes to constrain the regional source/sinks balance
An atmospheric perspective on North American carbon dioxide exchange: CarbonTracker
We present an estimate of net CO2 exchange between the terrestrial biosphere and the atmosphere across North America for every week in the period 2000 through 2005. This estimate is derived from a set of 28,000 CO2 mole fraction observations in the global atmosphere that are fed into a state-of-the-art data assimilation system for CO2 called CarbonTracker. By design, the surface fluxes produced in CarbonTracker are consistent with the recent history of CO2 in the atmosphere and provide constraints on the net carbon flux independent from national inventories derived from accounting efforts. We find the North American terrestrial biosphere to have absorbed –0.65 PgC/yr (1 petagram = 10^15 g; negative signs are used for carbon sinks) averaged over the period studied, partly offsetting the estimated 1.85 PgC/yr release by fossil fuel burning and cement manufacturing. Uncertainty on this estimate is derived from a set of sensitivity experiments and places the sink within a range of –0.4 to –1.0 PgC/yr. The estimated sink is located mainly in the deciduous forests along the East Coast (32%) and the boreal coniferous forests (22%). Terrestrial uptake fell to –0.32 PgC/yr during the large-scale drought of 2002, suggesting sensitivity of the contemporary carbon sinks to climate extremes. CarbonTracker results are in excellent agreement with a wide collection of carbon inventories that form the basis of the first North American State of the Carbon Cycle Report (SOCCR), to be released in 2007. All CarbonTracker results are freely available at http://carbontracker.noaa.gov
ObsPack: a framework for the preparation, delivery, and attribution of atmospheric greenhouse gas data
Observation Package (ObsPack) is a framework designed to bring
together atmospheric greenhouse gas observations from a variety of
sampling platforms, prepare them with specific applications in mind,
and package and distribute them in a self-consistent and
well-documented product. Data products created using the ObsPack framework (called "ObsPack products")
are intended to support carbon cycle modeling studies and represent the next
generation of value-added greenhouse gas observation products modeled after the
cooperative GLOBALVIEW products introduced in 1996.
Depending on intended use, ObsPack products may include data
in their original form reformatted using the ObsPack framework or
may contain derived data consisting of averages, subsets or smoothed
representations of original data. All products include extensive
ancillary information (metadata) intended to help ensure the data
are used appropriately, their calibration and quality assurance
history are clearly described, and that individuals responsible for
the measurements (data providers or principal investigators (PIs))
are properly acknowledged for their work. ObsPack products are made
freely available using a distribution strategy designed to improve
communication between data providers and product users. The strategy
includes a data usage policy that requires users to directly
communicate with data providers and an automated e-mail notification
system triggered when a product is accessed. ObsPack products will be assigned a unique Digital Object Identifier (DOI) to ensure each product can be unambiguously identified in scientific literature. Here we describe the ObsPack framework and its potential role in supporting the evolving needs of both data providers and product users
ObsPack: a framework for the preparation, delivery, and attribution of atmospheric greenhouse gas measurements
Observation Package (ObsPack) is a framework designed to bring together
atmospheric greenhouse gas observations from a variety of sampling platforms,
prepare them with specific applications in mind, and package and distribute
them in a self-consistent and well-documented product. Data products created
using the ObsPack framework (called "ObsPack products") are intended to
support carbon cycle modeling studies and represent a next generation of
value-added greenhouse gas observation products modeled after the cooperative
GLOBALVIEW products introduced in 1996. Depending on intended use, ObsPack
products may include data in their original form reformatted using the
ObsPack framework or may contain derived data consisting of averages,
subsets,
or smoothed representations of original data. All products include extensive
ancillary information (metadata) intended to help ensure the data are used
appropriately, their calibration and quality assurance history are clearly
described, and that individuals responsible for the measurements (data
providers or principal investigators (PIs)) are properly acknowledged for
their work. ObsPack products are made freely available using a distribution
strategy designed to improve communication between data providers and product
users. The strategy includes a data usage policy that requires users to
directly communicate with data providers and an automated e-mail notification
system triggered when a product is accessed. ObsPack products will be
assigned a unique digital object identifier (DOI) to ensure each product can
be unambiguously identified in scientific literature. Here we describe the
ObsPack framework and its potential role in supporting the evolving needs of
both data providers and product users
Математична залежність точності верстатних пристроїв від їх ступеня гнучкості
Підвищення конкурентоспроможності продукції, що виробляється
невеликими підприємствами, забезпечується шляхом скорочення витрат на
проектування та виготовлення технологічної оснастки для свердлильно-
фрезерно-розточувальних операцій. Це стає можливим за рахунок
використання гнучких верстатних пристроїв (ВП), що мають можливість
переналагодження у заданому діапазоні розмірів заготовки шляхом
регулювання установлювально-затискних елементів
A statistical gap-filling method to interpolate global monthly surface ocean carbon dioxide data
We have developed a statistical gap-filling method adapted to the specific coverage and prop-erties of observed fugacity of surface ocean CO2(fCO2). We have used this method to interpolate the Sur-face Ocean CO2Atlas (SOCAT) v2 database on a 2.5832.58 global grid (south of 708N) for 1985–2011 atmonthly resolution. The method combines a spatial interpolation based on a ‘‘radius of influence’’ to deter-mine nearby similar fCO2values with temporal harmonic and cubic spline curve-fitting, and also fits long-term trends and seasonal cycles. Interannual variability is established using deviations of observations fromthe fitted trends and seasonal cycles. An uncertainty is computed for all interpolated values based on thespatial and temporal range of the interpolation. Tests of the method using model data show that it performsas well as or better than previous regional interpolation methods, but in addition it provides a near-globaland interannual coverage
Reversal of Long-Term Trends in Ethane Identified from the Global Atmosphere Watch Reactive Gases Measurement Network
Reactive gases play an important role in climate and air pollution issues. They control the self-cleansing capability of the troposphere, contribute to air pollution and acid deposition, regulate the lifetimes and provide tracers for deciphering sources and sinks for greenhouse gases. Within GAW, the focus is placed on long-term, high-quality observations of ozone (O3), carbon monoxide (CO), volatile organic compounds (VOC), nitrogen oxides (NOx), and sulfur dioxide (SO2). More than 100 stations worldwide carry out reactive gases measurements with data reported to two World Data Centers. The reactive gases program in GAW cooperates The WMO GAW Reactive Gases Program with regional networks and other global monitoring initiatives in order to attain a complete picture of the tropospheric chemical composition. Observations are being made by in-situ monitoring, measurements from commercial routine air-crafts (e.g. IAGOS), column observations, and from flask sampling networks. Quality control and coordination of measurements between participating stations are a primary emphasis. GAW reactive gases data in rapid delivery mode are used to evaluate operational atmospheric composition forecasts in the EU Copernicus Atmospheric Monitoring Service. Oversight of the program is provided by GAW-WMO coordinated Reactive Gases Scientific Advisory Committee (RG-SAG)
Impact of CO2 measurement bias on CarbonTracker surface flux estimates
For over 20 years, atmospheric measurements of CO2 dry air mole fractions have been used to derive estimates of CO2 surface fluxes. Historically, only a few research laboratories made these measurements. Today, many laboratories are making CO2 observations using a variety of analysis techniques and, in some instances, using different calibration scales. As a result, the risk of biases in individual CO2 mole fraction records, or even in complete monitoring networks, has increased over the last decades. Ongoing experiments comparing independent, well-calibrated measurements of atmospheric CO2 show that biases can and do exist between measurement records. Biases in measurements create artificial spatial and temporal CO2 gradients, which are then interpreted by an inversion system, leading to erroneous flux estimates. Here we evaluate the impact of a constant bias introduced into the National Oceanic and Atmospheric Administration (NOAA) quasi-continuous measurement record at the Park Falls, Wisconsin (LEF), tall tower site on CarbonTracker flux estimates. We derive a linear relationship between the magnitude of the introduced bias at LEF and the CarbonTracker surface flux responses. Temperate North American net flux estimates are most sensitive to a bias at LEF in our CarbonTracker inversion, and its linear response rate is 68 Tg C yr-1 (~10% of the estimated North American annual terrestrial uptake) for every 1 ppm of bias in the LEF record. This sensitivity increases when (1) measurement biases approached assumed model errors and (2) fewer other measurement records are available to anchor the flux estimates despite the presence of bias in one record. Flux estimate errors are also calculated beyond North America. For example, biospheric uptake in Europe and boreal Eurasia combined increases by 25 Tg C yr-1 per ppm CO2 to partially compensate for changes in the North American flux totals. These results illustrate the importance of well-calibrated, high-precision CO2 dry air mole fraction measurements, as well as the value of an effective strategy for detecting bias in measurements. This study stresses the need for a monitoring network with the necessary density to anchor regional, continental, and hemispheric fluxes more tightly and to lessen the impact of potentially undetected biases in observational networks operated by different national and international research programs
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