Showing papers in "Bulletin of the American Meteorological Society in 2012"
TL;DR: The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance the authors' knowledge of climate variability and climate change.
Abstract: The fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance our knowledge of climate variability and climate change. Researchers worldwide are analyzing the model output and will produce results likely to underlie the forthcoming Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Unprecedented in scale and attracting interest from all major climate modeling groups, CMIP5 includes “long term” simulations of twentieth-century climate and projections for the twenty-first century and beyond. Conventional atmosphere–ocean global climate models and Earth system models of intermediate complexity are for the first time being joined by more recently developed Earth system models under an experiment design that allows both types of models to be compared to observations on an equal footing. Besides the longterm experiments, CMIP5 calls for an entirely new suite of “near term” simulations focusing on recent decades...
12,384 citations
TL;DR: The Local Climate Zone (LCZ) classification system as discussed by the authors was developed to address the inadequacies of urban-rural description, and consists of 17 zone types at the local scale (102 to 104 m).
Abstract: The effect of urban development on local thermal climate is widely documented in scientific literature. Observations of urban–rural air temperature differences—or urban heat islands (UHIs)—have been reported for cities and regions worldwide, often with local field sites that are extremely diverse in their physical and climatological characteristics. These sites are usually described only as “urban” or “rural,” leaving much uncertainty about the actual exposure and land cover of the sites. To address the inadequacies of urban–rural description, the “local climate zone” (LCZ) classification system has been developed. The LCZ system comprises 17 zone types at the local scale (102 to 104 m). Each type is unique in its combination of surface structure, cover, and human activity. Classification of sites into appropriate LCZs requires basic metadata and surface characterization. The zone definitions provide a standard framework for reporting and comparing field sites and their temperature observations. The LCZ s...
2,340 citations
TL;DR: A daily gridded precipitation dataset covering a period of more than 57 yr was created by collecting and analyzing rain gauge observation data across Asia through the activities of the Asian Precipitation-Highly Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE) project.
Abstract: A daily gridded precipitation dataset covering a period of more than 57 yr was created by collecting and analyzing rain gauge observation data across Asia through the activities of the Asian Precipitation—Highly Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE) project. APHRODITE's daily gridded precipitation is presently the only long-term, continental-scale, high-resolution daily product. The product is based on data collected at 5,000–12,000 stations, which represent 2.3–4.5 times the data made available through the Global Telecommunication System network and is used for most daily gridded precipitation products. Hence, the APHRODITE project has substantially improved the depiction of the areal distribution and variability of precipitation around the Himalayas, Southeast Asia, and mountainous regions of the Middle East. The APHRODITE project now contributes to studies such as the determination of Asian monsoon precipitation change, evaluation of water resources, ...
1,408 citations
TL;DR: In this paper, the authors present recent efforts to understand the relative accuracies of different instrumentation and gauges with various windshield configurations to measure snowfall and highlight results from the National Center for Atmospheric Research (NCAR) Marshall Field Site.
Abstract: This paper presents recent efforts to understand the relative accuracies of different instrumentation and gauges with various windshield configurations to measure snowfall. Results from the National Center for Atmospheric Research (NCAR) Marshall Field Site will be highlighted. This site hosts a test bed to assess various solid precipitation measurement techniques and is a joint collaboration between the National Oceanic and Atmospheric Administration (NOAA), NCAR, the National Weather Service (NWS), and Federal Aviation Administration (FAA). The collaboration involves testing new gauges and other solid precipitation measurement techniques in comparison with World Meteorological Organization (WMO) reference snowfall measurements. This assessment is critical for any ongoing studies and applications, such as climate monitoring and aircraft deicing, that rely on accurate and consistent precipitation measurements.
569 citations
TL;DR: In this article, real-time model predictions of ENSO conditions during the 2002-11 period are evaluated and compared to skill levels documented in studies of the 1990s, finding that decadal variations in the character of EnsO variability are a greater skill-determining factor than the steady but gradual trend toward improved ENSo prediction science and models.
Abstract: Real-time model predictions of ENSO conditions during the 2002–11 period are evaluated and compared to skill levels documented in studies of the 1990s. ENSO conditions are represented by the Nino- 3.4 SST index in the east-central tropical Pacific. The skills of 20 prediction models (12 dynamical, 8 statistical) are examined. Results indicate skills somewhat lower than those found for the less advanced models of the 1980s and 1990s. Using hindcasts spanning 1981–2011, this finding is explained by the relatively greater predictive challenge posed by the 2002–11 period and suggests that decadal variations in the character of ENSO variability are a greater skill-determining factor than the steady but gradual trend toward improved ENSO prediction science and models. After adjusting for the varying difficulty level, the skills of 2002–11 are slightly higher than those of earlier decades. Unlike earlier results, the average skill of dynamical models slightly, but statistically significantly, exceeds that of sta...
542 citations
TL;DR: The North American Regional Climate Change Assessment Program (NARCCAP) is an international effort designed to investigate the uncertainties in regional-scale projections of future climate and produce highresolution climate change scenarios using multiple regional climate models (RCMs) nested within atmosphere-ocean general circulation models (AOGCMs) forced with the Special Report on Emission Scenarios (SRES) A2 scenario, with a common domain covering the conterminous United States, northern Mexico, and most of Canada as discussed by the authors.
Abstract: The North American Regional Climate Change Assessment Program (NARCCAP) is an international effort designed to investigate the uncertainties in regional-scale projections of future climate and produce highresolution climate change scenarios using multiple regional climate models (RCMs) nested within atmosphere–ocean general circulation models (AOGCMs) forced with the Special Report on Emission Scenarios (SRES) A2 scenario, with a common domain covering the conterminous United States, northern Mexico, and most of Canada. The program also includes an evaluation component (phase I) wherein the participating RCMs, with a grid spacing of 50 km, are nested within 25 years of National Centers for Environmental Prediction–Department of Energy (NCEP–DOE) Reanalysis II. This paper provides an overview of evaluations of the phase I domain-wide simulations focusing on monthly and seasonal temperature and precipitation, as well as more detailed investigation of four subregions. The overall quality of the simulations i...
445 citations
TL;DR: In this article, the authors present a synthesis of the main characteristics of this phenomenon, a conceptual framework for its causes, and an overview of potential environmental implications, as well as a discussion of climate change and mitigation strategies.
Abstract: A fundamental determinant of climate and life on our planet is the solar radiation (sunlight) incident at the Earth's surface. Any change in this precious energy source affects our habitats profoundly. Until recently, for simplicity and lack of better knowledge, the amount of solar radiation received at the Earth's surface was assumed to be stable over the years. However, there is increasing observational evidence that this quantity undergoes significant multidecadal variations, which need to be accounted for in discussions of climate change and mitigation strategies. Coherent periods and regions with prevailing declines (“dimming”) and inclines (“brightening”) in surface solar radiation have been detected in the worldwide observational networks, often in accord with anthropogenic air pollution patterns. The present synthesis provides in a nutshell the main characteristics of this phenomenon, a conceptual framework for its causes, and an overview of potential environmental implications. The latest develop...
399 citations
TL;DR: In this article, the authors illustrate some approaches to answering questions about the role of human factors, and the relative role of different natural factors, for six specific extreme weather or climate events of 2011.
Abstract: Attribution of extreme events shortly after their occurrence stretches the current state-of-theart of climate change assessment. To help foster the growth of this science, this article illustrates some approaches to answering questions about the role of human factors, and the relative role of different natural factors, for six specific extreme weather or climate events of 2011. Not every event is linked to climate change. The rainfall associated with the devastating Thailand floods can be explained by climate variability. But long-term warming played a part in the others. While La Nina contributed to the failure of the rains in the Horn of Africa, an increased frequency of such droughts there was linked to warming in the Western Pacific– Indian Ocean warm pool. Europe's record warm temperatures would probably not have been as unusual if the high temperatures had been caused only by the atmospheric flow regime without any long-term warming. Calculating how the odds of a particular extreme event have change...
398 citations
TL;DR: An overview of the scientific capabilities of WRFDA is provided, and together with results from sample operation implementations at the U.S. and international levels, the challenges associated with balancing academic, research, and operational data assimilation requirements in the context of the WRF effort to date are discussed.
Abstract: Data assimilation is the process by which observations are combined with short-range NWP model output to produce an analysis of the state of the atmosphere at a specified time. Since its inception in the late 1990s, the multiagency Weather Research and Forecasting (WRF) model effort has had a strong data assimilation component, dedicating two working groups to the subject. This article documents the history of the WRF data assimilation effort, and discusses the challenges associated with balancing academic, research, and operational data assimilation requirements in the context of the WRF effort to date. The WRF Model's Community Variational/Ensemble Data Assimilation System (WRFDA) has evolved over the past 10 years, and has resulted in over 30 refereed publications to date, as well as implementation in a wide range of real-time and operational NWP systems. This paper provides an overview of the scientific capabilities of WRFDA, and together with results from sample operation implementations at the U.S. ...
391 citations
Met Office1, Centre national de la recherche scientifique2, EUMETSAT3, National Oceanic and Atmospheric Administration4, Université libre de Bruxelles5, University of Paris6, National Center for Atmospheric Research7, University of Leicester8, Belgian Institute for Space Aeronomy9, University of Basilicata10, European Centre for Medium-Range Weather Forecasts11, University of Maryland, Baltimore County12, University of Wisconsin-Madison13, Langley Research Center14
TL;DR: The Infrared Atmospheric Sounding Interferometer (IASI) as discussed by the authors is the main sounding component of EUMETSAT's Metop-A satellite, which was launched in October 2006.
Abstract: Four years after launch, IASI has delivered significant advances in remote sensing capability for numerical weather prediction and atmospheric composition monitoring and promises an excellent dataset for climate studies. The Infrared Atmospheric Sounding Interferometer (IASI) forms the main infrared sounding component of EUMETSAT's Metop-A satellite (Klaes et al., 2007), which was launched in October 2006. This article presents the results of the first four years of the operational IASI mission. The performance of the instrument is shown to be exceptional in terms of calibration and stability the quality of the data has allowed the rapid use of the observations in operational numerical weather prediction (NWP) and the development of new products for atmospheric chemistry and climate studies, some of which were unexpected before launch. The assimilation of IASI observations in NWP models provides significant forecast impact; in most cases the impact has been shown to be at least as large as for any previous instrument. In atmospheric chemistry, global distributions of gases such as ozone and carbon monoxide can be produced in near-real time, and short-lived species such as ammonia or methanol can be mapped, allowing identification of new sources. The data have also shown the ability to track the location and chemistry of gaseous plumes and particles associated with volcanic eruptions and fires, providing valuable data for air quality monitoring and aircraft safety. IASI also contributes to the establishment of robust long term data records of several essential climate variables. The suite of products being developed from IASI continues to expand as the data are investigated, and further impacts are expected from increased use of the data in NWP and climate studies in the coming years. The instrument has set a high standard for future operational hyperspectral infrared sounders, and demonstrated that such instruments have a vital role in the global observing system.
361 citations
TL;DR: The U.S. Climate Reference Network (USCRN) as discussed by the authors consists of 114 sites across the conterminous 48 states, with additional sites in Alaska and Hawaii, where a suite of meteorological parameters are monitored, including triple redundancy for the primary air temperature and precipitation variables and for soil moisture/temperature.
Abstract: The year 2012 marks a decade of observations undertaken by the U.S. Climate Reference Network (USCRN) under the auspices of NOAA's National Climatic Data Center and Atmospheric Turbulence and Diffusion Division. The network consists of 114 sites across the conterminous 48 states, with additional sites in Alaska and Hawaii. Stations are installed in open (where possible), rural sites very likely to have stable land-cover/use conditions for several decades to come. At each site a suite of meteorological parameters are monitored, including triple redundancy for the primary air temperature and precipitation variables and for soil moisture/temperature. Instrumentation is regularly calibrated to National Institute for Standards and Technology (NIST) standards and maintained by a staff of expert engineers. This attention to detail in USCRN is intended to ensure the creation of an unimpeachable record of changes in surface climate over the United States for decades to come. Data are made available without restric...
TL;DR: The U.S. Climate Normals as mentioned in this paper is a long-standing product line of the National Oceanic and Atmospheric Administration (NOAA) that provides a comprehensive suite of precipitation, snowfall, and snow depth statistics.
Abstract: The National Oceanic and Atmospheric Administration (NOAA) released the 1981–2010 U.S. Climate Normals in July 2011, representing the latest decadal installment of this long-standing product line. Climatic averages (and other statistics) of temperature, precipitation, snowfall, and numerous derived quantities were calculated for ~9,800 stations operated by the U.S. National Weather Service (NWS). They include estimated normals, or “quasi normals,” for approximately 2,000 active short-record stations such as those in the U.S. Climate Reference Network. The 1981–2010 installment features several new products and methodological enhancements: 1) state-of-the-art temperature homogenization at the monthly scale, 2) extensive utilization of quality-controlled daily climate data, 3) new statistical approaches for calculating daily temperature normals and heating and cooling degree days, and 4) a comprehensive suite of precipitation, snowfall, and snow depth statistics. This paper provides a general overview of th...
TL;DR: Overall, taking a unified approach has given enormous benefits, both scientific and in terms of efficiency, but some of the challenges it has presented and the approaches taken to overcome them are detailed.
Abstract: In recent years there has been a growing appreciation of the potential advantages of using a seamless approach to weather and climate prediction However, what exactly should this mean in practice? To help address this question, we document some of the experiences already gathered over 25 years of developing and using the Met Office Unified Model (MetUM) for both weather and climate prediction Overall, taking a unified approach has given enormous benefits, both scientific and in terms of efficiency, but we also detail some of the challenges it has presented and the approaches taken to overcome them
TL;DR: The 2010 NOAA/HWT Spring Forecasting Experiment (SE2010), conducted 17 May through 18 June, had a broad focus, with emphases on heavy rainfall and aviation weather, through collaboration with the Hydrometeorological Prediction Center (HPC) and the Aviation Weather Center (AWC), respectively as discussed by the authors.
Abstract: The NOAA Hazardous Weather Testbed (HWT) conducts annual spring forecasting experiments organized by the Storm Prediction Center and National Severe Storms Laboratory to test and evaluate emerging scientific concepts and technologies for improved analysis and prediction of hazardous mesoscale weather. A primary goal is to accelerate the transfer of promising new scientific concepts and tools from research to operations through the use of intensive real-time experimental forecasting and evaluation activities conducted during the spring and early summer convective storm period. The 2010 NOAA/HWT Spring Forecasting Experiment (SE2010), conducted 17 May through 18 June, had a broad focus, with emphases on heavy rainfall and aviation weather, through collaboration with the Hydrometeorological Prediction Center (HPC) and the Aviation Weather Center (AWC), respectively. In addition, using the computing resources of the National Institute for Computational Sciences at the University of Tennessee, the Center for A...
TL;DR: The Merged Land-Ocean Surface Temperature Analysis (MLOST) 3.5 as mentioned in this paper is the most recent version of the MLOST dataset, which is used in operational monitoring and climate assessment activities by the NOAA National Climatic Data Center.
Abstract: This paper describes the new release of the Merged Land–Ocean Surface Temperature analysis (MLOST version 3.5), which is used in operational monitoring and climate assessment activities by the NOAA National Climatic Data Center. The primary motivation for the latest version is the inclusion of a new land dataset that has several major improvements, including a more elaborate approach for addressing changes in station location, instrumentation, and siting conditions. The new version is broadly consistent with previous global analyses, exhibiting a trend of 0.076°C decade−1 since 1901, 0.162°C decade−1 since 1979, and widespread warming in both time periods. In general, the new release exhibits only modest differences with its predecessor, the most obvious being very slightly more warming at the global scale (0.004°C decade−1 since 1901) and slightly different trend patterns over the terrestrial surface.
TL;DR: The State of the Climate for 2011 as mentioned in this paper is a very low-resolution file and it can be downloaded in a few minutes for a high-resolution version of the report to download.
Abstract: Editors note: For easy download the posted pdf of the State of the Climate for 2011 is a very low-resolution file. A high-resolution copy of the report is available by clicking here. Please be patient as it may take a few minutes for the high-resolution file to download. Supplemental figures and datasets are available here.
TL;DR: Ralph et al. as mentioned in this paper presented the results of a study on the relationship between ocean currents and ocean dynamics, and the results showed that ocean currents can be represented as a function of the amount of water in the ocean.
Abstract: AMERICAN METEOROLOGICAL SOCIETY | JUNE 2012| 783 PB AFFILIATIONS: Ralph—NOAA/ESRL, Physical Sciences Division, Boulder, Colorado; DettingeR—U.S. Geological Survey, Scripps Institution of Oceanography, La Jolla, California CORRESPONDING AUTHOR: F. Martin Ralph, NOAA/Earth System Research Laboratory, Physical Sciences Division, 325 Broadway, R/PSD2, Boulder, CO 80305-3328 E-mail: marty.ralph@noaa.gov
TL;DR: A qualitative overview of the main relevant surface gravity wave-driven processes at the air-sea interface that may have an important role in the coupled climate system in general and the atmospheric and oceanic boundary layers in particular is provided in this article.
Abstract: The role waves play in modulating interactions between oceans and atmosphere is emphasized. All exchanges (e.g., momentum, energy, heat, mass, radiation fluxes) are influenced by the geometrical and physical characteristics of the ocean surface, which separates the atmospheric and oceanic boundary layers. A qualitative overview of the main relevant surface gravity wave–driven processes at the air–sea interface that may have an important role in the coupled climate system in general and the atmospheric and oceanic boundary layers in particular is provided.
TL;DR: Ho et al. as mentioned in this paper proposed a model for predicting the future of the UK's weather system based on the NCAS climate and the Department of Meteorology at the University of Reading.
Abstract: aMErICan METEOrOLOGICaL SOCIETy | 21 AffiliAtions: Ho—NCAS–Climate and the Department of Meteorology, University of Reading, Reading, United Kingdom; StepHenSon and Ferro—NCAS–Climate and Mathematics Research Institute, University of Exeter, Exeter, United Kingdom; CollinS—Mathematics Research Institute, University of Exeter, and Met Office Hadley Centre, Exeter, United Kingdom; Brown—Met Office Hadley Centre, Exeter, United Kingdom Corresponding Author: Chun Kit Ho, Department of Meteorology, University of Reading, Earley Gate, P.O. Box 243, Reading RG6 6BB, UK E-mail: c.k.ho@reading.ac.uk
California Institute of Technology1, National Center for Atmospheric Research2, World Meteorological Organization3, University of Cologne4, Indian Institute of Tropical Meteorology5, Naval Postgraduate School6, Met Office7, National Taiwan University8, Monash University9, State University of New York System10, Colorado State University11, Karlsruhe Institute of Technology12, University of Leeds13, Bureau of Meteorology14, University of Arizona15, University of Washington16, North Carolina State University17
TL;DR: In this paper, the authors highlight the diverse array of scientifically interesting and socially important weather and climate events in the year of tropical convection (YOTC) and use these constructs to advance the characterization, modeling, parameterization, and prediction of multiscale tropical convections, including relevant two-way interactions between tropical and extratropical systems.
Abstract: The representation of tropical convection remains a serious challenge to the skillfulness of our weather and climate prediction systems. To address this challenge, the World Climate Research Programme (WCRP) and The Observing System Research and Predictability Experiment (THORPEX) of the World Weather Research Programme (WWRP) are conducting a joint research activity consisting of a focus period approach along with an integrated research framework tailored to exploit the vast amounts of existing observations, expanding computational resources, and the development of new, high-resolution modeling frameworks. The objective of the Year of Tropical Convection (YOTC) is to use these constructs to advance the characterization, modeling, parameterization, and prediction of multiscale tropical convection, including relevant two-way interactions between tropical and extratropical systems. This article highlights the diverse array of scientifically interesting and socially important weather and climate events assoc...
TL;DR: The NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) provides near-real-time precipitation data sets and services for research and applications as discussed by the authors, which consist of orbital data from TRMM instruments at sensor s resolution, gridded data at a range of spatial and temporal resolutions, subsets, ground-based instrument data, and ancillary data.
Abstract: Precipitation is a critical component of the Earth's hydrological cycle. Launched on 27 November 1997, TRMM is a joint U.S.-Japan satellite mission to provide the first detailed and comprehensive data set of the four-dimensional distribution of rainfall and latent heating over vastly under-sampled tropical and subtropical oceans and continents (40 S - 40 N). Over the past 14 years, TRMM has been a major data source for meteorological, hydrological and other research and application activities around the world. The purpose of this short article is to inform that the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) provides TRMM archive and near-real-time precipitation data sets and services for research and applications. TRMM data consist of orbital data from TRMM instruments at the sensor s resolution, gridded data at a range of spatial and temporal resolutions, subsets, ground-based instrument data, and ancillary data. Data analysis, display, and delivery are facilitated by the following services: (1) Mirador (data search and access); (2) TOVAS (TRMM Online Visualization and Analysis System); (3) OPeNDAP (Open-source Project for a Network Data Access Protocol); (4) GrADS Data Server (GDS); and (5) Open Geospatial Consortium (OGC) Web Map Service (WMS) for the GIS community. Precipitation data application services are available to support a wide variety of applications around the world. Future plans include enhanced and new services to address data related issues from the user community. Meanwhile, the GES DISC is preparing for the Global Precipitation Measurement (GPM) mission which is scheduled for launch in 2014.
Courant Institute of Mathematical Sciences1, National Oceanic and Atmospheric Administration2, Complutense University of Madrid3, University of Reading4, Max Planck Society5, Cooperative Institute for Research in Environmental Sciences6, Columbia University7, United States Naval Research Laboratory8, Met Office9, Lamont–Doherty Earth Observatory10, McGill University11, Japan Agency for Marine-Earth Science and Technology12
TL;DR: New modeling efforts will provide unprecedented opportunities to harness our knowledge of the stratosphere to improve weather and climate prediction as mentioned in this paper, and we are excited to be a part of these efforts....
Abstract: New modeling efforts will provide unprecedented opportunities to harness our knowledge of the stratosphere to improve weather and climate prediction.
TL;DR: Polyakov et al. as discussed by the authors proposed a method to use the International Arctic Research Center (IARC) at the University of Alaska Fairbanks (UAF) in Fairbanks, Alaska.
Abstract: aMerICaN MeTeOrOLOGICaL SOCIeTy | 145 AffiliAtions: Polyakov and Walsh—International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, Alaska; kWok—Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California CoRREsPonDinG AUtHoR: Igor V. Polyakov, International Arctic Research Center, University of Alaska Fairbanks, P.O. Box 757335, Fairbanks, AK 99775 E-mail: igor@iarc.uaf.edu
TL;DR: In this article, an empirical C-band cross-polarization ocean (C-2PO) model for wind retrievals from synthetic aperture radar data collected by the RADARSAT-2 satellite is presented.
Abstract: We present an empirical C-band Cross-Polarization Ocean (C-2PO) model for wind retrievals from synthetic aperture radar (SAR) data collected by the RADARSAT-2 satellite. The C-2PO model relates normalized radar cross section (NRCS) in cross polarization to wind speed at 10-m height. This wind retrieval model has the characteristic that it is independent of wind direction and radar incidence angle but is quite linear with respect to wind speed. To evaluate the accuracy of the proposed model, winds with a resolution on the scale of 1 km were retrieved from a dual-polarization SAR image of Hurricane Earl on 2 September 2010, using the C-2PO model and compared with CMOD5.N, the newest available C-band geophysical model function (GMF), and validated with collocated airborne stepped-frequency microwave radiometer measurements and National Data Buoy Center data. Results suggest that for winds up to 38 m s−1, C-2PO has a bias of −0.89 m s−1 and a root-meansquare error of 3.23 m s−1 compared to CMOD5.N, which has ...
TL;DR: In this paper, the current understanding of past, present, and future changes in the Atlantic meridional overturning circulation and the effects of such changes on climate are reviewed, as well as the outstanding challenges and possible future directions for AMOC research are outlined.
Abstract: Observations and numerical modeling experiments provide evidence for links between variability in the Atlantic meridional overturning circulation (AMOC) and global climate patterns. Reduction in the strength of the overturning circulation is thought to have played a key role in rapid climate change in the past and may have the potential to significantly influence climate change in the future, as noted in the last two Intergovernmental Panel on Climate Change (IPCC) assessment reports (Houghton et al.; Solomon et al.). Both IPCC reports also highlighted the significant uncertainties that exist regarding the future behavior of the AMOC under global warming. Model results suggest that changes in the AMOC can impact surface air temperature, precipitation patterns, and sea level, particularly in areas bordering the North Atlantic, thus affecting human populations. Here, the current understanding of past, present, and future changes in the AMOC and the effects of such changes on climate are reviewed. The focus is on observations of the AMOC, how the AMOC influences climate, and in what way the AMOC is likely to change over the next few decades and the twenty-first century. The potential for decadal prediction of the AMOC is also discussed. Finally, the outstanding challenges and possible future directions for AMOC research are outlined.
TL;DR: The second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) as mentioned in this paper was designed to explore the physical processes of tornadogenesis, maintenance, and demise.
Abstract: The second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2), which had its field phases in May and June of 2009 and 2010, was designed to explore i) the physical processes of tornadogenesis, maintenance, and demise; ii) the relationships among tornadoes, tornadic storms, and the larger-scale environment; iii) numerical weather prediction and forecasting of supercell thunderstorms and tornadoes; and iv) the wind field near the ground in tornadoes. VORTEX2 is by far the largest and most ambitious observational and modeling study of tornadoes and tornadic storms ever undertaken. It employed 13 mobile mesonet–instrumented vehicles, 11 ground-based mobile radars (several of which had dual-polarization capability and two of which were phased-array rapid scan), a mobile Doppler lidar, four mobile balloon sounding systems, 42 deployable in situ observational weather stations, an unmanned aerial system, video and photogrammetric teams, damage survey teams, deployable disdrometers, and othe...
TL;DR: In this paper, a ventilation index is introduced that is equal to the environmental vertical wind shear multiplied by the non-dimensional mid-level entropy deficit divided by the potential intensity.
Abstract: An important environmental control of both tropical cyclone intensity and genesis is vertical wind shear. One hypothesized pathway by which vertical shear affects tropical cyclones is midlevel ventilation—or the flux of low-entropy air into the center of the tropical cyclone. Based on a theoretical framework, a ventilation index is introduced that is equal to the environmental vertical wind shear multiplied by the nondimensional midlevel entropy deficit divided by the potential intensity. The ventilation index has a strong influence on tropical cyclone climatology. Tropical cyclogenesis preferentially occurs when and where the ventilation index is anomalously low. Both the ventilation index and the tropical cyclone's normalized intensity, or the intensity divided by the potential intensity, constrain the distribution of tropical cyclone intensification. The most rapidly intensifying storms are characterized by low ventilation indices and intermediate normalized intensities, while the most rapidly weakenin...
TL;DR: The Crop Wind Energy Experiment (CWEX) as mentioned in this paper was developed as a multi-government, multi-university, and multi-institutional experiment to evaluate the influence of wind turbines on surface fluxes between the vegetated surface and the lower boundary layer.
Abstract: Perturbations of mean and turbulent wind characteristics by large wind turbines modify fluxes between the vegetated surface and the lower boundary layer. While simulations have suggested that wind farms could significantly change surface fluxes of heat, momentum, momentum, moisture, and CO2 over hundreds of square kilometers, little observational evidence exists to test these predictions. Quantifying the influences of the “turbine layer” is necessary to quantify how surface fluxes are modified and to better forecast energy production by a wind farm. Changes in fluxes are particularly important in regions of intensely managed agriculture where crop growth and yield are highly dependent on subtle changes in moisture, heat, and CO2. Furthermore, speculations abound about the possible mesoscale consequences of boundary layer changes that are produced by wind farms. To address the lack of observations to answer these questions, we developed the Crop Wind Energy Experiment (CWEX) as a multiagency, multiuniversi...
TL;DR: The Enhanced Fujita (EF) scale as discussed by the authors provides wind speed estimates for a range of degrees of damage (DoDs) across each of 28 damage indicators (DIs) and has increased precision of damage surveys for tornado and thunderstorm-wind events.
Abstract: During the early to middle 2000s, in response to demand for more detail in wind damage surveying and recordkeeping, a team of atmospheric scientists and wind engineers developed the enhanced Fujita (EF) scale. The EF scale, codified officially into National Weather Service (NWS) use in February 2007, offers wind speed estimates for a range of degrees of damage (DoDs) across each of 28 damage indicators (DIs). In practice, this has increased precision of damage surveys for tornado and thunderstorm-wind events. Still, concerns remain about both the representativeness of DoDs and the sufficiency of DIs, including the following: How dependable are the wind speed ranges for certain DoDs? What other DIs can be included? How can recent advances in mapping and documentation tools be integrated into the surveying process and the storm records? What changes should be made to the existing scale: why, how, and by whom? What alternative methods may be included or adapted for estimating tornado intensity? To begin coor...
TL;DR: In this paper, the authors investigated the possible reasons and motivations underpinning the large body of work, as well as summarizing specific themes, approaches, and theoretical contributions arising from such study.
Abstract: Over the past 60 years, metropolitan Phoenix, Arizona, has been among the fastest-growing urban areas in the United States, and this rapid urbanization has resulted in an urban heat island (UHI) of substantial size and intensity. During this time, an uncommon amount of UHI-specific research, relative to other cities in North America, occurred within its boundaries. This review investigates the possible reasons and motivations underpinning the large body of work, as well as summarizing specific themes, approaches, and theoretical contributions arising from such study. It is argued that several factors intrinsic to Phoenix were responsible for the prodigious output: strong applied urban climate research partnerships between several agencies (such as the academy, the National Weather Service, private energy firms, and municipal governments); a high-quality, long-standing network of urban meteorological stations allowing for relatively fine spatial resolution of near-surface temperature data; and a high level...