Showing papers in "Bulletin of the American Meteorological Society in 2018"

WUDAPT: An Urban Weather, Climate, and Environmental Modeling Infrastructure for the Anthropocene

Abstract: The World Urban Database and Access Portal Tools (WUDAPT) is an international community-based initiative to acquire and disseminate climate relevant data on the physical geographies of cities for modeling and analysis purposes. The current lacuna of globally consistent information on cities is a major impediment to urban climate science toward informing and developing climate mitigation and adaptation strategies at urban scales. WUDAPT consists of a database and a portal system; its database is structured into a hierarchy representing different levels of detail, and the data are acquired using innovative protocols that utilize crowdsourcing approaches, Geowiki tools, freely accessible data, and building typology archetypes. The base level of information (L0) consists of local climate zone (LCZ) maps of cities; each LCZ category is associated with a range of values for model-relevant surface descriptors (roughness, impervious surface cover, roof area, building heights, etc.). Levels 1 (L1) and 2 (L2) will provide specific intra-urban values for other relevant descriptors at greater precision, such as data morphological forms, material composition data, and energy usage. This article describes the status of the WUDAPT project and demonstrates its potential value using observations and models. As a community-based project, other researchers are encouraged to participate to help create a global urban database of value to urban climate scientists.

The ITCZ and the Seasonal Cycle over Equatorial Africa

Abstract: The common explanation for the progression of the rainy season over Africa is the seasonal excursion of the ITCZ. The ITCZ paradigm stems from a time when tropical rainfall was assumed to be associated mainly with localized convection. Its development was also linked to the emergence of midlatitude frontal concepts. The paradigm has numerous shortcomings, including the diversity of definitions and the large number of parameters used to identify the ITCZ. A historical look at the concept shows that its use over Africa has long been controversial, with many eminent tropical meteorologists harshly criticizing its applicability over this continent. However, the seasonal excursion of the ITCZ remains the classical explanation for African rainy seasons, especially in the equatorial region. This article underscores the shortcomings of the paradigm in equatorial Africa by examining various aspects of the circulation associated with the spatial and temporal patterns of rainfall during the equatorial rainy ...

Predicting near-term changes in the Earth System: A large ensemble of initialized decadal prediction simulations using the Community Earth System Model

Abstract: CapsuleA new community data resource offers unprecedented statistical power for assessing hindcast accuracy and skill, quantifying the benefits associated with initialization, and exploring the probabilistic attributes of decadal predictions of climate and ocean biogeochemical fields.

Continental U.S. Hurricane Landfall Frequency and Associated Damage: Observations and Future Risks

Abstract: Continental United States (CONUS) hurricane-related inflation-adjusted damage has increased significantly since 1900 However, since 1900 neither observed CONUS landfalling hurricane freque

Defining “Atmospheric River”: How the Glossary of Meteorology Helped Resolve a Debate

Abstract: AFFILIATIONS: raLPh—Center for Western Weather and Water Extremes, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California; Dettinger—U.S. Geological Survey, Carson City, Nevada; CairnS*—Federal Aviation Administration, San Diego, California; gaLarneau—University of Arizona, Tucson, Arizona; eyLanDer—US Army Engineer Research and Development Center, Hanover, New Hampshire

Explaining Extreme Events of 2016 from a Climate Perspective

Abstract: Editors note: For easy download the posted pdf of the Explaining Extreme Events of 2016 is a very low-resolution file. A high-resolution copy of the report is available by clicking here. Please be ...

CESM1(WACCM) Stratospheric Aerosol Geoengineering Large Ensemble Project

Abstract: This paper describes the Stratospheric Aerosol Geoengineering Large Ensemble (GLENS) project, which promotes the use of a unique model dataset, performed with the Community Earth System Model, with the Whole Atmosphere Community Climate Model as its atmospheric component [CESM1(WACCM)], to investigate global and regional impacts of geoengineering. The performed simulations were designed to achieve multiple simultaneous climate goals, by strategically placing sulfur injections at four different locations in the stratosphere, unlike many earlier studies that targeted globally averaged surface temperature by placing injections in regions at or around the equator. This advanced approach reduces some of the previously found adverse effects of stratospheric aerosol geoengineering, including uneven cooling between the poles and the equator and shifts in tropical precipitation. The 20-member ensemble increases the ability to distinguish between forced changes and changes due to climate variability in global and regional climate variables in the coupled atmosphere, land, sea ice, and ocean system. We invite the broader community to perform in-depth analyses of climate-related impacts and to identify processes that lead to changes in the climate system as the result of a strategic application of stratospheric aerosol geoengineering.

State of the climate in 2017

Abstract: In 2017, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-reached new record highs. The annual global average carbon dioxide concentration at Earth's surface for 2017 was 405.0 ± 0.1 ppm, 2.2 ppm greater than for 2016 and the highest in the modern atmospheric measurement record and in ice core records dating back as far as 800 000 years. The global growth rate of CO2 has nearly quadrupled since the early 1960s. With ENSO-neutral conditions present in the central and eastern equatorial Pacific Ocean during most of the year and weak La Nina conditions notable at the start and end, the global temperature across land and ocean surfaces ranked as the second or third highest, depending on the dataset, since records began in the mid-to-late 1800s. Notably, it was the warmest non-El Nino year in the instrumental record. Above Earth's surface, the annual lower tropospheric temperature was also either second or third highest according to all datasets analyzed. The lower stratospheric temperature was about 0.2°C higher than the record cold temperature of 2016 according to most of the in situ and satellite datasets. Several countries, including Argentina, Uruguay, Spain, and Bulgaria, reported record high annual temperatures. Mexico broke its annual record for the fourth consecutive year. On 27 January, the temperature reached 43.4°C at Puerto Madryn, Argentina-the highest temperature recorded so far south (43°S) anywhere in the world. On 28 May in Turbat, western Pakistan, the high of 53.5°C tied Pakistan's all-time highest temperature and became the world-record highest temperature for May. In the Arctic, the 2017 land surface temperature was 1.6°C above the 1981-2010 average, the second highest since the record began in 1900, behind only 2016. The five highest annual Arctic temperatures have all occurred since 2007. Exceptionally high temperatures were observed in the permafrost across the Arctic, with record values reported in much of Alaska and northwestern Canada. In August, high sea surface temperature (SST) records were broken for the Chukchi Sea, with some regions as warm as +11°C, or 3° to 4°C warmer than the longterm mean (1982-present). According to paleoclimate studies, today's abnormally warm Arctic air and SSTs have not been observed in the last 2000 years. The increasing temperatures have led to decreasing Arctic sea ice extent and thickness. On 7 March, sea ice extent at the end of the growth season saw its lowest maximum in the 37-year satellite record, covering 8% less area than the 1981-2010 average. The Arctic sea ice minimum on 13 September was the eighth lowest on record and covered 25% less area than the long-term mean. Preliminary data indicate that glaciers across the world lost mass for the 38th consecutive year on record; the declines are remarkably consistent from region to region. Cumulatively since 1980, this loss is equivalent to slicing 22 meters off the top of the average glacier. Antarctic sea ice extent remained below average for all of 2017, with record lows during the first four months. Over the continent, the austral summer seasonal melt extent and melt index were the second highest since 2005, mostly due to strong positive anomalies of air temperature over most of the West Antarctic coast. In contrast, the East Antarctic Plateau saw record low mean temperatures in March. The year was also distinguished by the second smallest Antarctic ozone hole observed since 1988. Across the global oceans, the overall long-term SST warming trend remained strong. Although SST cooled slightly from 2016 to 2017, the last three years produced the three highest annual values observed; these high anomalies have been associated with widespread coral bleaching. The most recent global coral bleaching lasted three full years, June 2014 to May 2017, and was the longest, most widespread, and almost certainly most destructive such event on record. Global integrals of 0-700-m and 0-2000-m ocean heat content reached record highs in 2017, and global mean sea level during the year became the highest annual average in the 25-year satellite altimetry record, rising to 77 mm above the 1993 average. In the tropics, 2017 saw 85 named tropical storms, slightly above the 1981-2010 average of 82. The North Atlantic basin was the only basin that featured an above-normal season, its seventh most active in the 164-year record. Three hurricanes in the basin were especially notable. Harvey produced record rainfall totals in areas of Texas and Louisiana, including a storm total of 1538.7 mm near Beaumont, Texas, which far exceeds the previous known U.S. tropical cyclone record of 1320.8 mm. Irma was the strongest tropical cyclone globally in 2017 and the strongest Atlantic hurricane outside of the Gulf of Mexico and Caribbean on record with maximum winds of 295 km h-1. Maria caused catastrophic destruction across the Caribbean Islands, including devastating wind damage and flooding across Puerto Rico. Elsewhere, the western North Pacific, South Indian, and Australian basins were all particularly quiet. Precipitation over global land areas in 2017 was clearly above the long-term average. Among noteworthy regional precipitation records in 2017, Russia reported its second wettest year on record (after 2013) and Norway experienced its sixth wettest year since records began in 1900. Across India, heavy rain and flood-related incidents during the monsoon season claimed around 800 lives. In August and September, above-normal precipitation triggered the most devastating floods in more than a decade in the Venezuelan states of Bolivar and Delta Amacuro. In Nigeria, heavy rain during August and September caused the Niger and Benue Rivers to overflow, bringing floods that displaced more than 100 000 people. Global fire activity was the lowest since at least 2003; however, high activity occurred in parts of North America, South America, and Europe, with an unusually long season in Spain and Portugal, which had their second and third driest years on record, respectively. Devastating fires impacted British Columbia, destroying 1.2 million hectares of timber, bush, and grassland, due in part to the region's driest summer on record. In the United States, an extreme western wildfire season burned over 4 million hectares; the total costs of $18 billion tripled the previous U.S. annual wildfire cost record set in 1991.

The High Latitude Marine Heat Wave of 2016 and Its Impacts on Alaska

Abstract: Earth System Observations. The Gulf of Alaska (GOA) and Bering Sea have been anomalously warm for several years with the warmth peaking in 2016. As a consequence of the high marine heat content (HC) and SSTs, coastal areas of Alaska had their warmest winter–spring of record in 2016 (Walsh et al. 2017) and earliest river ice breakup for multiple Alaska rivers (www.weather.gov/aprfc/breakupDB). Observed marine warmth, impacts on the marine ecosystem, and an attribution analysis using CMIP5 models are presented here. The marine heat wave was first noted over deep waters of the northeastern Pacific Ocean in January 2014 (Freeland 2014; Bond et al. 2015); anomalous temperatures at coastal GOA stations arrived variously between January and June. Warm temperature anomalies were confined to the top 100 meters until late 2014, after which they penetrated to depths of 300 meters and reached strengths greater than 2 standard deviations (Roemmich and Gilson 2009). The consensus of previous studies is that atmospheric circulation anomalies played a key role in initiating and maintaining the North Pacific “blob” of warm water (Bond et al. 2015). Unusually high pressure south of the Gulf of Alaska reduced heat loss to the atmosphere and also reduced cold advection over the region. Forcing of the atmospheric anomalies has been linked to SST anomalies in the western tropical Pacific Ocean (Seager et al. 2015) and to decadal-scale modes of North Pacific Ocean variability (Di Lorenzo and Mantua 2016). Lee et al. (2015) have argued that sea ice anomalies also contributed to the atmospheric circulation anomalies in 2013/14. By contrast, the winter of 2015/16 was characterized by negative sea level pressure anomalies of more than 12 hPa centered in the eastern Bering Sea (Fig. ES8.1d). The associated northward airflow evident throughout the depth of the atmosphere (Fig. ES8.1b) likely drove lingering heat from the blob into the GOA and Bering Sea regions. An unusually deep Aleutian low is a typical feature of the El Niño conditions that characterized early 2016 (Walsh et al. 2017). The positive HC anomalies (Fig. 8.1a) reached an extreme in 2016 for the GOA and Bering Sea (Figs. 8.1d,e), with most of the region ranking in the top five warmest HCs of record (Fig. ES8.2a). Oceanic temperatures are from GODAS (Saha et al. 2006), NCEP’s high-resolution ocean analysis. HC was calculated by integrating ocean temperature (°C) from the surface to 300 meters or the bottom of each model water column. This value was then divided by the depth of its respective water column, the 1981–2010 mean was removed, and the quantity was normalized to allow comparison between the Bering Sea (51°–64.5°N, 180°–160°W) and GOA (50°–60°N, 150°–130°W) regions (Figs. 8.1d,e). AFFILIATIONS: walsh and brettsChneider—Alaska Center

The Benefits of Global High Resolution for Climate Simulation: Process Understanding and the Enabling of Stakeholder Decisions at the Regional Scale

Abstract: Capsule summary:A perspective on current and future capabilities in global high-resolution climate simulation for assessing climate risks over next few decades, including advances in process representation and analysis, justifying the emergence of dedicated, coordinated experimental protocols.

Earth Observations from DSCOVR/EPIC Instrument.

Abstract: The NOAA Deep Space Climate Observatory (DSCOVR) spacecraft was launched on February 11, 2015, and in June 2015 achieved its orbit at the first Lagrange point or L1, 1.5 million km from Earth towards the Sun. There are two NASA Earth observing instruments onboard: the Earth Polychromatic Imaging Camera (EPIC) and the National Institute of Standards and Technology Advanced Radiometer (NISTAR). The purpose of this paper is to describe various capabilities of the DSCOVR/EPIC instrument. EPIC views the entire sunlit Earth from sunrise to sunset at the backscattering direction (scattering angles between 168.5° and 175.5°) with 10 narrowband filters: 317, 325, 340, 388, 443, 552, 680, 688, 764 and 779 nm. We discuss a number of pre-processingsteps necessary for EPIC calibration including the geolocation algorithm and the radiometric calibration for each wavelength channel in terms of EPIC counts/second for conversion to reflectance units. The principal EPIC products are total ozone O3amount, scene reflectivity, erythemal irradiance, UV aerosol properties, sulfur dioxide SO2 for volcanic eruptions, surface spectral reflectance, vegetation properties, and cloud products including cloud height. Finally, we describe the observation of horizontally oriented ice crystals in clouds and the unexpected use of the O2 B-band absorption for vegetation properties.

The Global N2O Model Intercomparison Project

Abstract: Nitrous oxide (N2O) is an important greenhouse gas and also an ozone-depleting substance that has both natural and anthropogenic sources. Large estimation uncertainty remains on the magnitude and spatiotemporal patterns of N2O fluxes and the key drivers of N2O production in the terrestrial biosphere. Some terrestrial biosphere models have been evolved to account for nitrogen processes and to show the capability to simulate N2O emissions from land ecosystems at the global scale, but large discrepancies exist among their estimates primarily because of inconsistent input datasets, simulation protocol, and model structure and parameterization schemes. Based on the consistent model input data and simulation protocol, the global N2O Model Intercomparison Project (NMIP) was initialized with 10 state-of-the-art terrestrial biosphere models that include nitrogen (N) cycling. Specific objectives of NMIP are to 1) unravel the major N cycling processes controlling N2O fluxes in each model and identify the unc...

The grape remote sensing atmospheric profile and evapotranspiration experiment.

Abstract: Particularly in light of California’s recent multiyear drought, there is a critical need for accurate and timely evapotranspiration (ET) and crop stress information to ensure long-term sust...

Anthropogenic Intensification of Southern African Flash Droughts as Exemplified by the 2015/16 Season

Abstract: Introduction. Droughts are mainly driven by natural climate variability. They usually evolve slowly and persist for a few months to decades. Anthropogenic climate change, however, not only increases the likeli‐ hood of local and regional droughts, but also alters their characteristics (Sheffield and Wood 2008; Dai 2013; Trenberth et al. 2014). For instance, the soil moisture drought during growing seasons is often accompanied by heat waves, resulting in a type of drought that has a rapid onset and short duration (from a few days to 1–2 months), but high intensity and devastating impacts, which is recently termed “flash drought” (Hoerling et al. 2014; Mo and Letten‐ maier 2015; Yuan et al. 2015; Wang et al. 2016). During November–April of 2015/16, most parts of southern Africa (SA; 10°–40°E, 10°–35°S) experienced a rainy season–long drought. Within the seasonal drought, heat waves occurred suddenly, which caused a severe flash drought characterized by soil moisture deficit and heat waves at the beginning of December. The flash drought was then terminated by a rainfall event in early January. The South African Weather Service announced that 32 daily temperature records were broken in South Africa with the highest reaching 45°C. Millions of people were affected by famine, dis‐ ease, and water shortages. The SA drought is basically associated with the 2015/16 strong El Niño (Nicholson and Entekhabi 1986; Reason and Jagadheesha 2005; Yuan et al. 2013; Ratnam et al. 2014; Hoell et al. 2015) and possibly altered by Indian Ocean sea surface tem‐ perature variability (Reason 2001; Washington and Preston 2006; Manatsa et al. 2011; Hoell et al. 2016), but the warming climate may also play an important role. This study will investigate the 2015/16 SA flash drought in the context of a changing climate during 1948–2016, and detect the anthropogenic influences.

The North Atlantic Waveguide and Downstream Impact Experiment

Abstract: Multi-aircraft and ground-based observations were made over the North Atlantic in fall 2016 to investigate the importance of diabatic processes for midlatitude weather. The North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX) explored the impact of diabatic processes on disturbances of the jet stream and their influence on downstream high-impact weather through the deployment of four research aircraft, each with a sophisticated set of remote-sensing and in situ instruments, and coordinated with a suite of ground-based measurements. A total of 49 research flights were performed, including, for the first time, coordinated flights of the four aircraft; the German High Altitude and LOng Range Research Aircraft (HALO), the Deutsches Zentrum fur Luft- und Raumfahrt (DLR) Dassault Falcon 20, the French Service des Avions Francais Instrumentes pour la Recherche en Environnement (SAFIRE) Falcon 20, and the British Facility for Airborne Atmospheric Measurements (FAAM) BAe 146. The observation period from 17 Sep to 22 Oct 2016 with frequently occurring extratropical and tropical cyclones was ideal to investigate midlatitude weather over the North Atlantic. NAWDEX featured three sequences of upstream triggers of waveguide disturbances, their dynamic interaction with the jet stream, subsequent development, and eventual downstream weather impact on Europe. Examples are presented to highlight the wealth of phenomena that were sampled, the comprehensive coverage and the multi-faceted nature of the measurements. This unique dataset forms the basis for future case studies and detailed evaluations of weather and climate predictions to improve our understanding of diabatic influences on Rossby waves and downstream impact of weather systems affecting Europe.

A New Research Approach for Observing and Characterizing Land-Atmosphere Feedback

Abstract: Forecast errors with respect to wind, temperature, moisture, clouds, and precipitation largely correspond to the limited capability of current earth system models to capture and simulate land-atmosphere feedback To facilitate its realistic simulation in next generation models, an improved process understanding of the related complex interactions is essential To this end, accurate 3D observations of key variables in the land-atmosphere (L-A) system with high vertical and temporal resolution from the surface to the free troposphere are indispensable Recently, we developed a synergy of innovative ground-based, scanning active remote sensing systems for 2D to 3D measurements of wind, temperature, and water vapor from the surface to the lower troposphere that is able to provide comprehensive data sets for characterizing L-A feedback independently of any model input Several new applications are introduced such as the mapping of surface momentum, sensible heat, and latent heat fluxes in heterogeneous terrain, the testing of Monin-Obukhov similarity theory and turbulence parameterizations, the direct measurement of entrainment fluxes, and the development of new flux-gradient relationships An experimental design taking advantage of the sensors' synergy and advanced capabilities was realized for the first time during the Land Atmosphere Feedback Experiment (LAFE), conducted at the Atmospheric Radiation Measurement Program Southern Great Plains site in August 2017 The scientific goals and the strategy of achieving them with the LAFE data set are introduced We envision the initiation of innovative L-A feedback studies in different climate regions to improve weather forecast, climate, and earth system models worldwide

Forcing of Multiyear Extreme Ocean Temperatures that Impacted California Current Living Marine Resources in 2016

Abstract: Introduction. Recent record high sea surface temperature anomalies (SSTa) in the California Current Large Marine Ecosystem (CCLME; Fig. 6.1a) produced dramatic impacts on marine life (Cavole et al. 2016; Peterson et al. 2016; Welch 2016). While effects on many species and fisheries may have been short-lived, salmon fisheries, for example, were heavily impacted in 2016 due to multiyear persistence of unfavorable conditions. Negative impacts on CCLME salmon fisheries are likely to persist until at least 2019, as poor stream and 2014–16 ocean conditions directly influence the 2016–19 Chinook salmon abundance. U.S. West Coast Chinook salmon catches in 2016 were approximately 52% of the average catch since 2006, quotas for Chinook salmon fisheries were not met, and spawning escapements to the Klamath and Sacramento River basins were very low (PFMC 2017a). For 2017, the Klamath River Chinook salmon abundance forecast is the lowest on record, and salmon fishing has been sharply restricted from southern Oregon to southern California (PFMC 2017b). Our analysis focuses on the climatic drivers of the 2014–16 CCLME warm period and its extremity in the context of the past century. This study is motivated by an important question from a fisheries management perspective: to what extent were the 2014–16 extremes due to natural variability versus anthropogenic climate change?

FACETs: A Proposed Next-Generation Paradigm for High-Impact Weather Forecasting

Abstract: Recommendations by the National Research Council (NRC), the National Institute of Standards and Technology (NIST), and Weather-Ready Nation workshop participants have encouraged the Nationa...

SYNTHESIS OF THE SOUTHEAST ATMOSPHERE STUDIES: Investigating Fundamental Atmospheric Chemistry Questions

Abstract: The Southeast Atmosphere Studies (SAS), which included the Southern Oxidant and Aerosol Study (SOAS); the Southeast Nexus (SENEX) study; and the Nitrogen, Oxidants, Mercury and Aerosols: Distributions, Sources and Sinks (NOMADSS) study, was deployed in the field from 1 June to 15 July 2013 in the central and eastern United States, and it overlapped with and was complemented by the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. SAS investigated atmospheric chemistry and the associated air quality and climate-relevant particle properties. Coordinated measurements from six ground sites, four aircraft, tall towers, balloon-borne sondes, existing surface networks, and satellites provide in situ and remotely sensed data on trace-gas composition, aerosol physicochemical properties, and local and synoptic meteorology. Selected SAS findings indicate 1) dramatically reduced NOx concentrations have altered ozone production regimes; 2) indica...

LANFEX: A Field and Modeling Study to Improve Our Understanding and Forecasting of Radiation Fog

Abstract: CapsuleA collaborative field and modeling study used a small system of valleys as a natural laboratory to study the formation and evolution of fog.

Ecological Impacts of the 2015/16 El Niño in the Central Equatorial Pacific

Abstract: The authors thank Cisco Werner (NOAA/NMFS) for proposing this special issue and encouraging our submission. We thank each of the editors, Stephanie Herring, Peter Stott, and Nikos Christidis, for helpful guidance and support throughout the submittal process. We also thank each of the anonymous external reviewers for thoughtful guidance and suggestions to improve the manuscript. REB, TO, RV, AH, and BVA are grateful for support from the NOAA Coral Reef Conservation Program. AC acknowledges support from the National Science Foundation for the following awards: OCE 1537338, OCE 1605365, and OCE 1031971. This is PMEL contribution no. 4698. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government. The views expressed in the article are not necessarily those of the U.S. government. (NOAA Coral Reef Conservation Program; OCE 1537338 - National Science Foundation; OCE 1605365 - National Science Foundation; OCE 1031971 - National Science Foundation)

The community leveraged unified ensemble (CLUE) in the 2016 NOAA/hazardous weather testbed spring forecasting experiment

Abstract: CapsuleThe CLUE system represents an unprecedented effort to leverage several academic and government research institutions to help guide NOAA’s operational environmental modeling efforts at the convection-allowing scale.

Have We Reached the Limits of Predictability for Tropical Cyclone Track Forecasting

Abstract: The tropical cyclone is the largest single-day-impact meteorological event in the United States and worldwide through its effects from storm surge, extreme winds, freshwater flooding, and e...

Importance of Late Fall ENSO Teleconnection in the Euro-Atlantic Sector

Abstract: Recent studies have indicated the importance of fall climate forcings and teleconnections in influencing the climate of the northern mid-to-high latitudes. Here, we present some exploratory analyses using observational data and seasonal hindcasts, with the aim of highlighting the potential of the El Nino-Southern Oscillation (ENSO) as a driver of climate variability during boreal late fall/early winter (November/December) in the North Atlantic-European sector and motivating further research on this relatively unexplored topic. The atmospheric ENSO teleconnection in November/December is reminiscent of the East Atlantic pattern and distinct from the well-known arching extratropical Rossby wavetrain found from January to March. Temperature and precipitation over Europe in November are positively correlated with the Nino3.4 index, which suggests a potentially important ENSO climate impact during late fall. In particular, the ENSO-related temperature anomaly extends over a much larger area than during ...

A bird’s-eye view: Development of an operational ARM unmanned aerial capability for atmospheric research in Arctic Alaska

Abstract: Thorough understanding of aerosols, clouds, boundary layer structure, and radiation is required to improve the representation of the Arctic atmosphere in weather forecasting and climate models. To develop such understanding, new perspectives are needed to provide details on the vertical structure and spatial variability of key atmospheric properties, along with information over difficult-to-reach surfaces such as newly forming sea ice. Over the last three years, the U.S. Department of Energy (DOE) has supported various flight campaigns using unmanned aircraft systems [UASs, also known as unmanned aerial vehicles (UAVs) and drones] and tethered balloon systems (TBSs) at Oliktok Point, Alaska. These activities have featured in situ measurements of the thermodynamic state, turbulence, radiation, aerosol properties, cloud microphysics, and turbulent fluxes to provide a detailed characterization of the lower atmosphere. Alongside a suite of active and passive ground-based sensors and radiosondes deploy...

BoBBLE (Bay of Bengal Boundary Layer Experiment): Ocean-atmosphere interaction and its impact on the South Asian monsoon

Abstract: The Bay of Bengal (BoB) plays a fundamental role in controlling the weather systems that make up the South Asian summer monsoon system In particular, the southern BoB has cooler sea surfac

Human Influence on the Record-breaking Cold Event in January of 2016 in Eastern China

Abstract: Anthropogenic influences are estimated to have reduced the likelihood of an extreme cold event in midwinter with the intensity equal to or stronger than the record of 2016 in eastern China by about two‐thirds.

Surf: understanding and predicting urban convection and haze

Abstract: Urbanization modifies atmospheric energy and moisture balances, forming distinct features, e.g., urban heat islands (UHIs) and enhanced or decreased precipitation. These produce significant challenges to science and society, including rapid and intense flooding, heat waves strengthened by UHIs, and air pollutant haze. The Study of Urban-Impacts on Rainfall and Fog/Haze (SURF) has brought together international expertise on observations and modeling, meteorology and atmospheric chemistry, and research and operational forecasting. The SURF overall science objective is a better understanding of urban, terrain, convection, and aerosol interactions for improved forecast accuracy. Specific objectives include: a) promoting cooperative international research to improve understanding of urban summer convective precipitation and winter particulate episodes via extensive field studies; b) improving high-resolution urban weather and air quality forecast-models; and c) enhancing urban weather forecasts for soc...

CO2 and Carbon Emissions from Cities: Linkages to Air Quality, Socioeconomic Activity, and Stakeholders in the Salt Lake City Urban Area

Abstract: Urban areas are responsible for a substantial proportion of anthropogenic carbon emissions around the world. As global populations increasingly reside in cities, the role of urban emissions...

A Paper on the Tropical Intraseasonal Oscillation Published in 1963 in a Chinese Journal

Abstract: Capsule SummaryA study published in Chinese in 1963 documented a 40-50-day oscillation in the Asian monsoon region, eight years earlier than its discovery by Madden and Julian (1971).