Search Results

You are looking at 51 - 59 of 59 items for

  • Author or Editor: David Parsons x
  • Refine by Access: All Content x
Clear All Modify Search
Tammy M. Weckwerth
,
David B. Parsons
,
Steven E. Koch
,
James A. Moore
,
Margaret A. LeMone
,
Belay B. Demoz
,
Cyrille Flamant
,
Bart Geerts
,
Junhong Wang
, and
Wayne F. Feltz

The International H2O Project (IHOP_2002) is one of the largest North American meteorological field experiments in history. From 13 May to 25 June 2002, over 250 researchers and technical staff from the United States, Germany, France, and Canada converged on the Southern Great Plains to measure water vapor and other atmospheric variables. The principal objective of IHOP_2002 is to obtain an improved characterization of the time-varying three-dimensional water vapor field and evaluate its utility in improving the understanding and prediction of convective processes. The motivation for this objective is the combination of extremely low forecast skill for warm-season rainfall and the relatively large loss of life and property from flash floods and other warm-season weather hazards. Many prior studies on convective storm forecasting have shown that water vapor is a key atmospheric variable that is insufficiently measured. Toward this goal, IHOP_2002 brought together many of the existing operational and new state-of-the-art research water vapor sensors and numerical models.

The IHOP_2002 experiment comprised numerous unique aspects. These included several instruments fielded for the first time (e.g., reference radiosonde); numerous upgraded instruments (e.g., Wyoming Cloud Radar); the first ever horizontal-pointing water vapor differential absorption lidar (DIAL; i.e., Leandre II on the Naval Research Laboratory P-3), which required the first onboard aircraft avoidance radar; several unique combinations of sensors (e.g., multiple profiling instruments at one field site and the German water vapor DIAL and NOAA/Environmental Technology Laboratory Doppler lidar on board the German Falcon aircraft); and many logistical challenges. This article presents a summary of the motivation, goals, and experimental design of the project, illustrates some preliminary data collected, and includes discussion on some potential operational and research implications of the experiment.

Full access
Shushi Zhang
,
David B. Parsons
,
Xin Xu
,
Jisong Sun
,
Tianjie Wu
,
Abuduwaili Abulikemu
,
Fen Xu
,
Gang Chen
,
Wenqiang Shen
,
Lihang Liu
,
Xidi Zhang
,
Kun Zhang
, and
Wei Zhang

Abstract

The bow-and-arrow Mesoscale Convective System (MCS) has a unique structure with two convective lines resembling the shape of an archer’s bow and arrow. These MCSs and their arrow convection (located behind the MCS leading line) can produce hazardous winds and flooding extending over hundreds of kilometers, which are often poorly predicted in operational forecasts. This study examines the dynamics of a bow-and-arrow MCS observed over the Yangtze–Huai Plains of China, with a focus on the arrow convection provided. The analysis utilized backward trajectories and Lagrangian vertical momentum budgets to simulations employing the WRF‐ARW and CM1 models. Cells within the arrow in the WRF-ARW simulations of the MCS were elevated, initially forming as convectively unstable air within the low-level jet (LLJ), which gently ascended over the cold pool and converged with the MCS’s mesoscale convective vortex (MCV) at higher altitudes. The subsequent ascent in these cells was enhanced by dynamic pressure forcing due to the updraft being within a layer where the vertical shear changed with height due to the superposition of the LLJ and the MCV. These dynamic forcings initially played a larger role in the ascent than the parcel’s buoyancy. These findings were bolstered by idealized simulations employing the CM1 model. These results illustrate a challenge for accurately forecasting bow-and-arrow MCSs as the updraft magnitude depends on dynamical forcing associated with the interaction between vertical shear associated with the environment and due to convectively generated circulations.

Free access
Philippe Bougeault
,
Zoltan Toth
,
Craig Bishop
,
Barbara Brown
,
David Burridge
,
De Hui Chen
,
Beth Ebert
,
Manuel Fuentes
,
Thomas M. Hamill
,
Ken Mylne
,
Jean Nicolau
,
Tiziana Paccagnella
,
Young-Youn Park
,
David Parsons
,
Baudouin Raoult
,
Doug Schuster
,
Pedro Silva Dias
,
Richard Swinbank
,
Yoshiaki Takeuchi
,
Warren Tennant
,
Laurence Wilson
, and
Steve Worley

Ensemble forecasting is increasingly accepted as a powerful tool to improve early warnings for high-impact weather. Recently, ensembles combining forecasts from different systems have attracted a considerable level of interest. The Observing System Research and Predictability Experiment (THORPEX) Interactive Grand Globa l Ensemble (TIGGE) project, a prominent contribution to THORPEX, has been initiated to enable advanced research and demonstration of the multimodel ensemble concept and to pave the way toward operational implementation of such a system at the international level. The objectives of TIGGE are 1) to facilitate closer cooperation between the academic and operational meteorological communities by expanding the availability of operational products for research, and 2) to facilitate exploring the concept and benefits of multimodel probabilistic weather forecasts, with a particular focus on high-impact weather prediction. Ten operational weather forecasting centers producing daily global ensemble forecasts to 1–2 weeks ahead have agreed to deliver in near–real time a selection of forecast data to the TIGGE data archives at the China Meteorological Agency, the European Centre for Medium-Range Weather Forecasts, and the National Center for Atmospheric Research. The volume of data accumulated daily is 245 GB (1.6 million global fields). This is offered to the scientific community as a new resource for research and education. The TIGGE data policy is to make each forecast accessible via the Internet 48 h after it was initially issued by each originating center. Quicker access can also be granted for field experiments or projects of particular interest to the World Weather Research Programme and THORPEX. A few examples of initial results based on TIGGE data are discussed in this paper, and the case is made for additional research in several directions.

Full access
Melvyn Shapiro
,
Jagadish Shukla
,
Gilbert Brunet
,
Carlos Nobre
,
Michel Béland
,
Randall Dole
,
Kevin Trenberth
,
Richard Anthes
,
Ghassem Asrar
,
Leonard Barrie
,
Philippe Bougeault
,
Guy Brasseur
,
David Burridge
,
Antonio Busalacchi
,
Jim Caughey
,
Deliang Chen
,
John Church
,
Takeshi Enomoto
,
Brian Hoskins
,
Øystein Hov
,
Arlene Laing
,
Hervé Le Treut
,
Jochem Marotzke
,
Gordon McBean
,
Gerald Meehl
,
Martin Miller
,
Brian Mills
,
John Mitchell
,
Mitchell Moncrieff
,
Tetsuo Nakazawa
,
Haraldur Olafsson
,
Tim Palmer
,
David Parsons
,
David Rogers
,
Adrian Simmons
,
Alberto Troccoli
,
Zoltan Toth
,
Louis Uccellini
,
Christopher Velden
, and
John M. Wallace

The necessity and benefits for establishing the international Earth-system Prediction Initiative (EPI) are discussed by scientists associated with the World Meteorological Organization (WMO) World Weather Research Programme (WWRP), World Climate Research Programme (WCRP), International Geosphere–Biosphere Programme (IGBP), Global Climate Observing System (GCOS), and natural-hazards and socioeconomic communities. The proposed initiative will provide research and services to accelerate advances in weather, climate, and Earth system prediction and the use of this information by global societies. It will build upon the WMO, the Group on Earth Observations (GEO), the Global Earth Observation System of Systems (GEOSS) and the International Council for Science (ICSU) to coordinate the effort across the weather, climate, Earth system, natural-hazards, and socioeconomic disciplines. It will require (i) advanced high-performance computing facilities, supporting a worldwide network of research and operational modeling centers, and early warning systems; (ii) science, technology, and education projects to enhance knowledge, awareness, and utilization of weather, climate, environmental, and socioeconomic information; (iii) investments in maintaining existing and developing new observational capabilities; and (iv) infrastructure to transition achievements into operational products and services.

Full access
Stephen A. Cohn
,
Terry Hock
,
Philippe Cocquerez
,
Junhong Wang
,
Florence Rabier
,
David Parsons
,
Patrick Harr
,
Chun-Chieh Wu
,
Philippe Drobinski
,
Fatima Karbou
,
Stéphanie Vénel
,
André Vargas
,
Nadia Fourrié
,
Nathalie Saint-Ramond
,
Vincent Guidard
,
Alexis Doerenbecher
,
Huang-Hsiung Hsu
,
Po-Hsiung Lin
,
Ming-Dah Chou
,
Jean-Luc Redelsperger
,
Charlie Martin
,
Jack Fox
,
Nick Potts
,
Kathryn Young
, and
Hal Cole

Constellations of driftsonde systems— gondolas floating in the stratosphere and able to release dropsondes upon command— have so far been used in three major field experiments from 2006 through 2010. With them, high-quality, high-resolution, in situ atmospheric profiles were made over extended periods in regions that are otherwise very difficult to observe. The measurements have unique value for verifying and evaluating numerical weather prediction models and global data assimilation systems; they can be a valuable resource to validate data from remote sensing instruments, especially on satellites, but also airborne or ground-based remote sensors. These applications for models and remote sensors result in a powerful combination for improving data assimilation systems. Driftsondes also can support process studies in otherwise difficult locations—for example, to study factors that control the development or decay of a tropical disturbance, or to investigate the lower boundary layer over the interior Antarctic continent. The driftsonde system is now a mature and robust observing system that can be combined with flight-level data to conduct multidisciplinary research at heights well above that reached by current research aircraft. In this article we describe the development and capabilities of the driftsonde system, the exemplary science resulting from its use to date, and some future applications.

Full access
Florence Rabier
,
Steve Cohn
,
Philippe Cocquerez
,
Albert Hertzog
,
Linnea Avallone
,
Terry Deshler
,
Jennifer Haase
,
Terry Hock
,
Alexis Doerenbecher
,
Junhong Wang
,
Vincent Guidard
,
Jean-Noël Thépaut
,
Rolf Langland
,
Andrew Tangborn
,
Gianpaolo Balsamo
,
Eric Brun
,
David Parsons
,
Jérôme Bordereau
,
Carla Cardinali
,
François Danis
,
Jean-Pierre Escarnot
,
Nadia Fourrié
,
Ron Gelaro
,
Christophe Genthon
,
Kayo Ide
,
Lars Kalnajs
,
Charlie Martin
,
Louis-François Meunier
,
Jean-Marc Nicot
,
Tuuli Perttula
,
Nicholas Potts
,
Patrick Ragazzo
,
David Richardson
,
Sergio Sosa-Sesma
, and
André Vargas
Full access
Bart Geerts
,
David Parsons
,
Conrad L. Ziegler
,
Tammy M. Weckwerth
,
Michael I. Biggerstaff
,
Richard D. Clark
,
Michael C. Coniglio
,
Belay B. Demoz
,
Richard A. Ferrare
,
William A. Gallus Jr.
,
Kevin Haghi
,
John M. Hanesiak
,
Petra M. Klein
,
Kevin R. Knupp
,
Karen Kosiba
,
Greg M. McFarquhar
,
James A. Moore
,
Amin R. Nehrir
,
Matthew D. Parker
,
James O. Pinto
,
Robert M. Rauber
,
Russ S. Schumacher
,
David D. Turner
,
Qing Wang
,
Xuguang Wang
,
Zhien Wang
, and
Joshua Wurman

Abstract

The central Great Plains region in North America has a nocturnal maximum in warm-season precipitation. Much of this precipitation comes from organized mesoscale convective systems (MCSs). This nocturnal maximum is counterintuitive in the sense that convective activity over the Great Plains is out of phase with the local generation of CAPE by solar heating of the surface. The lower troposphere in this nocturnal environment is typically characterized by a low-level jet (LLJ) just above a stable boundary layer (SBL), and convective available potential energy (CAPE) values that peak above the SBL, resulting in convection that may be elevated, with source air decoupled from the surface. Nocturnal MCS-induced cold pools often trigger undular bores and solitary waves within the SBL. A full understanding of the nocturnal precipitation maximum remains elusive, although it appears that bore-induced lifting and the LLJ may be instrumental to convection initiation and the maintenance of MCSs at night.

To gain insight into nocturnal MCSs, their essential ingredients, and paths toward improving the relatively poor predictive skill of nocturnal convection in weather and climate models, a large, multiagency field campaign called Plains Elevated Convection At Night (PECAN) was conducted in 2015. PECAN employed three research aircraft, an unprecedented coordinated array of nine mobile scanning radars, a fixed S-band radar, a unique mesoscale network of lower-tropospheric profiling systems called the PECAN Integrated Sounding Array (PISA), and numerous mobile-mesonet surface weather stations. The rich PECAN dataset is expected to improve our understanding and prediction of continental nocturnal warm-season precipitation. This article provides a summary of the PECAN field experiment and preliminary findings.

Full access
Gilbert Brunet
,
David B. Parsons
,
Dimitar Ivanov
,
Boram Lee
,
Peter Bauer
,
Natacha B. Bernier
,
Veronique Bouchet
,
Andy Brown
,
Antonio Busalacchi
,
Georgina Campbell Flatter
,
Rei Goffer
,
Paul Davies
,
Beth Ebert
,
Karl Gutbrod
,
Songyou Hong
,
P. K. Kenabatho
,
Hans-Joachim Koppert
,
David Lesolle
,
Amanda H. Lynch
,
Jean-François Mahfouf
,
Laban Ogallo
,
Tim Palmer
,
Kevin Petty
,
Dennis Schulze
,
Theodore G. Shepherd
,
Thomas F. Stocker
,
Alan Thorpe
, and
Rucong Yu

Abstract

Our world is rapidly changing. Societies are facing an increase in the frequency and intensity of high-impact and extreme weather and climate events. These extremes together with exponential population growth and demographic shifts (e.g., urbanization, increase in coastal populations) are increasing the detrimental societal and economic impact of hazardous weather and climate events. Urbanization and our changing global economy have also increased the need for accurate projections of climate change and improved predictions of disruptive and potentially beneficial weather events on kilometer scales. Technological innovations are also leading to an evolving and growing role of the private sector in the weather and climate enterprise. This article discusses the challenges faced in accelerating advances in weather and climate forecasting and proposes a vision for key actions needed across the private, public, and academic sectors. Actions span (i) utilizing the new observational and computing ecosystems; (ii) strategies to advance Earth system models; (iii) ways to benefit from the growing role of artificial intelligence; (iv) practices to improve the communication of forecast information and decision support in our age of internet and social media; and (v) addressing the need to reduce the relatively large, detrimental impacts of weather and climate on all nations and especially on low-income nations. These actions will be based on a model of improved cooperation between the public, private, and academic sectors. This article represents a concise summary of the white paper on the Future of Weather and Climate Forecasting (2021) put together by the World Meteorological Organizations’ Open Consultative Platform.

Open access
Florence Rabier
,
Aurélie Bouchard
,
Eric Brun
,
Alexis Doerenbecher
,
Stéphanie Guedj
,
Vincent Guidard
,
Fatima Karbou
,
Vincent-Henri Peuch
,
Laaziz El Amraoui
,
Dominique Puech
,
Christophe Genthon
,
Ghislain Picard
,
Michael Town
,
Albert Hertzog
,
François Vial
,
Philippe Cocquerez
,
Stephen A. Cohn
,
Terry Hock
,
Jack Fox
,
Hal Cole
,
David Parsons
,
Jordan Powers
,
Keith Romberg
,
Joseph VanAndel
,
Terry Deshler
,
Jennifer Mercer
,
Jennifer S. Haase
,
Linnea Avallone
,
Lars Kalnajs
,
C. Roberto Mechoso
,
Andrew Tangborn
,
Andrea Pellegrini
,
Yves Frenot
,
Jean-Noël Thépaut
,
Anthony McNally
,
Gianpaolo Balsamo
, and
Peter Steinle

The Concordiasi project is making innovative observations of the atmosphere above Antarctica. The most important goals of the Concordiasi are as follows:

  • To enhance the accuracy of weather prediction and climate records in Antarctica through the assimilation of in situ and satellite data, with an emphasis on data provided by hyperspectral infrared sounders. The focus is on clouds, precipitation, and the mass budget of the ice sheets. The improvements in dynamical model analyses and forecasts will be used in chemical-transport models that describe the links between the polar vortex dynamics and ozone depletion, and to advance the under understanding of the Earth system by examining the interactions between Antarctica and lower latitudes.

  • To improve our understanding of microphysical and dynamical processes controlling the polar ozone, by providing the first quasi-Lagrangian observations of stratospheric ozone and particles, in addition to an improved characterization of the 3D polar vortex dynamics. Techniques for assimilating these Lagrangian observations are being developed.

A major Concordiasi component is a field experiment during the austral springs of 2008–10. The field activities in 2010 are based on a constellation of up to 18 long-duration stratospheric super-pressure balloons (SPBs) deployed from the McMurdo station. Six of these balloons will carry GPS receivers and in situ instruments measuring temperature, pressure, ozone, and particles. Twelve of the balloons will release dropsondes on demand for measuring atmospheric parameters. Lastly, radiosounding measurements are collected at various sites, including the Concordia station.

Full access