Browse

You are looking at 11 - 20 of 23,534 items for :

  • Bulletin of the American Meteorological Society x
  • Refine by Access: Content accessible to me x
Clear All
Mathias W. Rotach, Stefano Serafin, Helen C. Ward, Marco Arpagaus, Ioana Colfescu, Joan Cuxart, Stephan F. J. De Wekker, Vanda Grubišic, Norbert Kalthoff, Thomas Karl, Daniel J. Kirshbaum, Manuela Lehner, Stephen Mobbs, Alexandre Paci, Elisa Palazzi, Adriana Bailey, Jürg Schmidli, Christoph Wittmann, Georg Wohlfahrt, and Dino Zardi

Abstract

In this essay, we highlight some challenges the atmospheric community is facing concerning adequate treatment of flows over mountains and their implications for numerical weather prediction (NWP), climate simulations, and impact modeling. With recent increases in computing power (and hence model resolution) numerical models start to face new limitations (such as numerical instability over steep terrain). At the same time there is a growing need for sufficiently reliable NWP model output to drive various impact models (for hydrology, air pollution, agriculture, etc.). The input information for these impact models is largely produced by the boundary layer (BL) parameterizations of NWP models. All known BL parameterizations assume flat and horizontally homogeneous surface conditions, and their performance and interaction with resolved flows is massively understudied over mountains—hence their output may be accidentally acceptable at best. We therefore advocate the systematic investigation of the so-called “mountain boundary layer” (MoBL), introduced to emphasize its many differences to the BL over flat and horizontally homogeneous terrain.

An international consortium of scientists has launched a research program, TEAMx (Multi-Scale Transport and Exchange Processes in the Atmosphere over Mountains–Program and Experiment), to address some of the most pressing scientific challenges. TEAMx is endorsed by World Weather Research Programme (WWRP) and the Global Energy and Water Exchanges (GEWEX) project as a “cross-cutting project.” A program coordination office was established at the University of Innsbruck (Austria). This essay introduces the background to and content of a recently published white paper outlining the key research questions of TEAMx.

Full access
Sara Morris and Taneil Uttal

Abstract

Creation of metadata (data about data) takes many forms and has many standards, much of which are designed to provide information for computer algorithms to find, access, and distribute data rather than for how humans might ingest data information. The humans (engineers, technicians, operators, scientists, data managers) that are increasingly tasked with being the providers of standard scientific metadata by the data science community also have a critical need for a different kind of metadata: metadata that can be used in the field (often offline) that provide a detailed visual map of the pathway taken by the electronic signal from a measuring device to a finalized, quality controlled geophysical variable. Datagrams presented here have been developed to fill this requirement and are a user-friendly, information-rich, graphical format that outline, record, and detail the critical information and steps involved with origin, collection, dataflow, processing, and archiving of data. Datagrams are designed to provide critical information across engineering, maintenance, data processing, and scientific teams that might speak different languages but are all required to process and maintain the data or instrument. The essential components of datagrams developed for instruments operating at remote Arctic stations are described here, but of course the concept is applicable to any type of observing protocol in any location.

Full access
Neil P. Lareau, Nicholas J. Nauslar, Evan Bentley, Matthew Roberts, Samuel Emmerson, Brian Brong, Matthew Mehle, and James Wallman

Abstract

Fire-generated tornadic vortices (FGTVs) linked to deep pyroconvection, including pyrocumulonimbi (pyroCbs), are a potentially deadly, yet poorly understood, wildfire hazard. In this study we use radar and satellite observations to examine three FGTV cases during high-impact wildfires during the 2020 fire season in California. We establish that these FGTVs each exhibit tornado-strength anticyclonic rotation, with rotational velocity as strong as 30 m s−1 (60 kt), vortex depths of up to 4.9 km AGL, and pyroCb plume tops as high as 16 km MSL. These data suggest similarities to EF2+ strength tornadoes. Volumetric renderings of vortex and plume morphology reveal two types of vortices: embedded vortices anchored to the fire and residing within high-reflectivity convective columns and shedding vortices that detach from the fire and move downstream. Time-averaged radar data further show that each case exhibits fire-generated mesoscale flow perturbations characterized by flow splitting around the fire’s updraft and pronounced flow reversal in the updraft’s lee. All the FGTVs occur during deep pyroconvection, including pyroCb, suggesting an important role of both fire and cloud processes. The commonalities in plume and vortex morphology provide the basis for a conceptual model describing when, where, and why these FGTVs form.

Full access
Lexi Henny, Lauriana C. Gaudet, Kevin M. Lupo, Kenya Goods, Shadya Sanders, and Yanda Zhang

Abstract

The U.S.–Taiwan Partnership for International Research and Education (PIRE) “Building Extreme Weather Resiliency through Improved Weather and Climate Prediction and Emergency Response Strategies” was an NSF-funded grant between universities and institutions in the United States and Taiwan that intended to understand 1) weather forecast uncertainty during extreme precipitation events and 2) how emergency managers use such information to make decisions. In this reflective paper, graduate students from the project’s working groups, including climate, ensemble, microphysics, and decision science, share their experiences of being involved in this ambitious program. A notable strength of this PIRE was its opportunities for international collaboration and related cultural experiences; however, despite direct student involvement in PIRE, student experiences varied considerably (e.g., research experiences, cultural exposure). Recommendations for improvement are informed predominantly by U.S.-based graduate student experiences and are discussed with the intention of bolstering future interdisciplinary research for students and investigators. To this end, projects of this scale and scope could benefit from more frequent communication among leadership and research groups, as well as explicitly outlining and prioritizing interactions between groups to focus and strengthen collaboration toward the completion of interdisciplinary research goals.

Full access
James C. Fallon, Hannah C. Bloomfield, David J. Brayshaw, Sarah N. Sparrow, David C. H. Wallom, Tim Woollings, Kate Brown, Laura Dawkins, Erika Palin, Nikolaus Houben, Daniel Huppmann, and Bruno U. Schyska
Open access
M.A. ObregÓn, M.T. Rodas, A.M.M. Farrona, F. Domínguez-Castro, M.C. Gallego, R. García-Herrera, and J.M. Vaquero

Abstract

Great advances in meteorological science were made in the late 18th century. In particular, meteorological instruments were carried on ships and the first systematic meteorological readings over the oceans were made. One of these collections of instrumental meteorological readings was carried out by the Malaspina expedition (1789-1794), organized by the Spanish crown to study its vast possessions around the world. We have recovered meteorological variables such as air temperature (maximum and minimum), atmospheric pressure (maximum and minimum), wind (intensity and direction), and appearance (state of the sky) from the documentation generated by the explorers during the journey. In total, nearly 13 000 instrumental data have been digitized and rescued from this maritime expedition. The comparison of daily temperature and pressure observations with reanalysis and weather stations data shows a good overall agreement. Moreover, apparent discrepancies during several anchored periods have allowed for testing the consistency and quality of these early instrumental marine weather readings.

Full access
René Garreaud, M. Ralph, A. Wilson, A.M. Ramos, J. Eiras-Barca, H. Steen-Larsen, J. Rutz, C. Albano, N. Tilinina, M. Warner, M. Viale, R. Rondanelli, J. McPhee, R. Valenzuela, and I. Gorodetskaya
Full access
David M. Hondula, Samuel Meltzer, Robert C. Balling Jr., and Paul Iñiguez

Abstract

Public heat alerts are important risk communication tools, but there has been no systematic analysis of how frequently they are issued, or how patterns in alert frequency relate to regional climatology or heat-health impacts. We compiled and analyzed all Excessive Heat Warnings and Heat Advisories (collectively, Heat Alerts) issued by the United States National Weather Service for 2010–2019. Heat Alert frequency was correlated to climatological indicators derived from reanalysis data aggregated to Weather Forecast Office (WFO) polygons, and to estimates of heat-attributable mortality for 134 metropolitan areas.

The type of Heat Alerts used, and the frequency with which they were issued, were highly variable. Across 77% of the country, Heat Advisories were the primary product issued. The median location experienced 2.3 Heat Alert days per year. Regions with the highest frequency (approaching 25 days per year) included the southern Midwest and Great Plains, as well as the desert Southwest. The 95th percentile daily maximum heat index was the climatological indicator most strongly correlated with Heat Alert frequency across all WFOs (r=0.71). Locations that issued Heat Alerts more frequently than would be expected based on climatology were primarily located along the Pacific coast; those that issued Heat Alerts less frequently than expected were in southern Texas and southern Florida, the latter of which includes multiple cities with high rates of heat-attributable mortality. Our results suggest that the public may be receiving mixed signals about the severity of the heat hazard, with some hotter locations particularly underserved by heat risk messaging.

Full access
Lei Wang, Lan Cuo, Dongliang Luo, Fengge Su, Qinghua Ye, Tandong Yao, Jing Zhou, Xiuping Li, Ning Li, He Sun, Lei Liu, Yuanwei Wang, Tian Zeng, Zhidan Hu, Ruishun Liu, Chenhao Chai, Guangpeng Wang, Xiaoyang Zhong, Xiaoyu Guo, Haoqiang Zhao, Huabiao Zhao, and Wei Yang

Abstract

Upper Brahmaputra (UB) is the largest (∼240,000km2) river basin of the Tibetan Plateau, where hydrological processes are highly sensitive to climate change. However, constrained by difficult access and sparse in-situ observations, the variations in precipitation, glaciers, frozen ground and vegetation across the UB basin remain largely unknown, and consequently the impacts of climate change on streamflow cannot be accurately assessed. To fill this gap, this project aims to establish a basin-wide, large-scale observational network (that includes hydrometeorology, glacier, frozen ground, and vegetation observations), which helps quantify the UB runoff processes under climate-cryosphere-vegetation changes. At present, a multi-sphere observational network has been established throughout the catchment. (1) Twelve stations with custom-built weighing automatic rain/snow meters and temperature probes to obtain elevation-dependent gradients. (2) Nine stations with soil moisture/temperature observations at four layers (10/40/80/120cm) covering alpine meadow, grasslands, shrub and forest to measure vegetation (biomass and vegetation types) and soil (physical properties) simultaneously. (3) Thirty-four sets of probes to monitor frozen ground temperatures from 4500 to 5200m elevation (100m intervals), and two observation systems to monitor water and heat transfer processes in frozen ground at Xuegela (5278m) and Mayoumula (5256m) Mountains, for improved mapping of permafrost and active layer characteristics. (4) Five sets of altimetry discharge observations along ungauged cross-sections to supplement existing operational gauges. (5) High-precision glacier boundary and ice-surface elevation observations at Namunani Mountain with differential GPS, to supplement existing glacier observations for validating satellite imagery. This network provides an excellent opportunity to monitor UB catchment processes in great detail.

Full access
Amy McGovern, Ann Bostrom, Phillip Davis, Julie L. Demuth, Imme Ebert-Uphof, Ruoying He, Jason Hickey, David John Gagne II, Nathan Snook, Jebb Q. Stewart, Christopher Thorncroft, Philippe Tissot, and John K. Williams

Abstract

We introduce the National Science Foundation (NSF) AI Institute for Research on Trustworthy AI in Weather, Climate, and Coastal Oceanography (AI2ES). This AI institute was funded in 2020 as part of a new initiative from the NSF to advance foundational AI research across a wide variety of domains. To date AI2ES is the only NSF AI institute focusing on environmental science applications. Our institute focuses on developing trustworthy AI methods for weather, climate, and coastal hazards. The AI methods will revolutionize our understanding and prediction of high-impact atmospheric and ocean science phenomena and will be utilized by diverse, professional user groups to reduce risks to society. In addition, we are creating novel educational paths, including a new degree program at a community college serving underrepresented minorities, to improve workforce diversity for both AI and environmental science.

Full access