OBSERVATIONAL ANALYSIS of the PREDICTABILITY of MESOSCALE CONVECTIVE SYSTEMS by Israel L
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Water Vapour Transport to the High Latitudes: Mechanisms And
Water vapour transport to the high latitudes : mechanisms and variability from reanalyses and radiosoundings Ambroise Dufour To cite this version: Ambroise Dufour. Water vapour transport to the high latitudes : mechanisms and variability from reanalyses and radiosoundings. Earth Sciences. Université Grenoble Alpes, 2016. English. NNT : 2016GREAU042. tel-01562031 HAL Id: tel-01562031 https://tel.archives-ouvertes.fr/tel-01562031 Submitted on 13 Jul 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. THÈSE Pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ DE GRENOBLE Spécialité : Sciences de la Terre et de l’Environnement Arrêté ministériel : 7 août 2006 Présentée par Ambroise DUFOUR Thèse dirigée par Olga ZOLINA préparée au sein du Laboratoire de Glaciologie et Géophysique de l’Environnement et de l’École Doctorale Terre, Univers, Environnement Transport de vapeur d’eau vers les hautes latitudes Mécanismes et variabilité d’après réanalyses et radiosondages Soutenue le 24 mars 2016, devant le jury composé de : M. Christophe GENTHON Directeur de recherche, LGGE, Président M. Stefan BRÖNNIMANN Professeur, Université de Berne, Rapporteur M. Richard P. ALLAN Professeur, Université de Reading, Rapporteur Mme Valérie MASSON-DELMOTTE Directrice de recherche, LSCE, Examinatrice M. -
Moisture Transport in Observations and Reanalyses As a Proxy for Snow
Moisture transport in observations and reanalyses as a proxy for snow accumulation in East Antarctica Ambroise DufourIGE, Claudine CharrondièreIGE, and Olga ZolinaIGE, IORAS IGEInstitut des Géosciences de l’Environnement, CNRS/UGA, Grenoble, France IORASP. P. Shirshov Institute of Oceanology, Russian Academy of Science, Moscow, Russia Correspondence to: Ambroise DUFOUR ([email protected]) Abstract. Atmospheric moisture convergence on ice-sheets provides an estimate of snow accumulation which is critical to quantify sea level changes. In the case of East Antarctica, we computed moisture transport from 1980 to 2016 in five reanalyses and in radiosonde observations. Moisture convergence in reanalyses is more consistent than net preciptation but still ranges from 72 5 to 96 mm per year in the four most recent reanalyses, ERA Interim, NCEP CFSR, JRA 55 and MERRA 2. The representation of long term variability in reanalyses is also inconsistent which justified the resort to observations. Moisture fluxes are measured on a daily basis via radiosondes launched from a network of stations surrounding East Antarc- tica. Observations agree with reanalyses on the major role of extreme advection events and transient eddy fluxes. Although assimilated, the observations reveal processes reanalyses cannot model, some due to a lack of horizontal and vertical resolu- 10 tion especially the oldest, NCEP DOE R2. Additionally, the observational time series are not affected by new satellite data unlike reanalyses. We formed pan-continental estimates of convergence by aggregating anomalies from all available stations. We found statistically significant trends neither in moisture convergence nor in precipitable water. 1 Introduction East Antarctica stores the equivalent of 53.3 m of sea level rise out of the 58.3 for the whole continent (Fretwell et al., 2013). -
Seasonal Cycle of Idealized Polar Clouds: Large Eddy
ESSOAr | https://doi.org/10.1002/essoar.10503204.1 | CC_BY_NC_ND_4.0 | First posted online: Tue, 9 Jun 2020 15:35:29 | This content has not been peer reviewed. manuscript submitted to Journal of Advances in Modeling Earth Systems 1 Seasonal cycle of idealized polar clouds: large eddy 2 simulations driven by a GCM 1 2;3 2 4 3 Xiyue Zhang , Tapio Schneider , Zhaoyi Shen , Kyle G. Pressel , and Ian 5 4 Eisenman 1 5 National Center for Atmospheric Research, Boulder, Colorado, USA 2 6 California Institute of Technology, Pasadena, California, USA 3 7 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA 4 8 Pacific Northwest National Labratory, Richland, Washington, USA 5 9 Scripps Institution of Oceanography, University of California, San Diego, California, USA 10 Key Points: 11 • LES driven by time-varying large-scale forcing from an idealized GCM is used to 12 simulate the seasonal cycle of Arctic clouds 13 • Simulated low-level cloud liquid is maximal in late summer to early autumn, and 14 minimal in winter, consistent with observations 15 • Large-scale advection provides the main moisture source for cloud liquid and shapes 16 its seasonal cycle Corresponding author: X. Zhang, [email protected] {1{ ESSOAr | https://doi.org/10.1002/essoar.10503204.1 | CC_BY_NC_ND_4.0 | First posted online: Tue, 9 Jun 2020 15:35:29 | This content has not been peer reviewed. manuscript submitted to Journal of Advances in Modeling Earth Systems 17 Abstract 18 The uncertainty in polar cloud feedbacks calls for process understanding of the cloud re- 19 sponse to climate warming. -
Atmospheric Instability Parameters Derived from Msg Seviri Observations
P3.33 ATMOSPHERIC INSTABILITY PARAMETERS DERIVED FROM MSG SEVIRI OBSERVATIONS Marianne König*, Stephen Tjemkes, Jochen Kerkmann EUMETSAT, Darmstadt, Germany 1. INTRODUCTION K-Index: Convective systems can develop in a thermo- (Tobs(850)–Tobs(500)) + TDobs(850) – (Tobs(700)–TDobs(700)) dynamically unstable atmosphere. Such systems may quickly reach high altitudes and can cause severe Lifted Index: storms. Meteorologists are thus especially interested to Tobs - Tlifted from surface at 500 hPa identify such storm potentials when the respective system is still in a preconvective state. A number of Maximum buoyancy: obs(max betw. surface and 850) obs(min betw. 700 and 300) instability indices have been defined to describe such Qe - Qe situations. Traditionally, these indices are taken from temperature and humidity soundings by radiosondes. As (T is temperature, TD is dewpoint temperature, and Qe radiosondes are only of very limited temporal and is equivalent potential temperature, numbers 850, 700, spatial resolution there is a demand for satellite-derived 300 indicate respective hPa level in the atmosphere) indices. The Meteorological Product Extraction Facility (MPEF) for the new European Meteosat Second and the precipitable water content as additionally Generation (MSG) satellite envisages the operational derived parameter. derivation of a number of instability indices from the brightness temperatures measured by certain SEVIRI 3. DESCRIPTION OF ALGORITHMS channels (Spinning Enhanced Visible and Infrared Imager, the radiometer onboard MSG). The traditional 3.1 The Physical Retrieval physical approach to this kind of retrieval problem is to infer the atmospheric profile via a constrained inversion An iterative solution to the inversion equation (e.g. and compute the indices then directly from the obtained Ma et al. -
Basic Features on a Skew-T Chart
Skew-T Analysis and Stability Indices to Diagnose Severe Thunderstorm Potential Mteor 417 – Iowa State University – Week 6 Bill Gallus Basic features on a skew-T chart Moist adiabat isotherm Mixing ratio line isobar Dry adiabat Parameters that can be determined on a skew-T chart • Mixing ratio (w)– read from dew point curve • Saturation mixing ratio (ws) – read from Temp curve • Rel. Humidity = w/ws More parameters • Vapor pressure (e) – go from dew point up an isotherm to 622mb and read off the mixing ratio (but treat it as mb instead of g/kg) • Saturation vapor pressure (es)– same as above but start at temperature instead of dew point • Wet Bulb Temperature (Tw)– lift air to saturation (take temperature up dry adiabat and dew point up mixing ratio line until they meet). Then go down a moist adiabat to the starting level • Wet Bulb Potential Temperature (θw) – same as Wet Bulb Temperature but keep descending moist adiabat to 1000 mb More parameters • Potential Temperature (θ) – go down dry adiabat from temperature to 1000 mb • Equivalent Temperature (TE) – lift air to saturation and keep lifting to upper troposphere where dry adiabats and moist adiabats become parallel. Then descend a dry adiabat to the starting level. • Equivalent Potential Temperature (θE) – same as above but descend to 1000 mb. Meaning of some parameters • Wet bulb temperature is the temperature air would be cooled to if if water was evaporated into it. Can be useful for forecasting rain/snow changeover if air is dry when precipitation starts as rain. Can also give -
Observational Study of a Diurnal Mesoscale Convective Complex
CRARP 25-02 OBSERVATIONAL STUDY OF A DIURNAL MESOSCALE CONVECTIVE COMPLEX David Novak1 and Edward Shimon National Weather Service Forecasting Office Duluth, Minnesota 1. Introduction The Mesoscale Convective Complex (MCC) has been described by Maddox (1980), Bosart and Sanders (1981), and Maddox (1983) as a unique class of intense convection organized on the meso-alpha scale, which occurs primarily in the central United States during the convective season. Fritsch et al. (1981) and Wetzel (1983) showed that MCCs produce locally intense rainfall, large hail, and damaging winds, requiring coincident operational warnings of both severe weather and flash flooding. In contrast to most convection MCCs are distinctly nocturnal (Maddox 1983). Augustine and Caracena (1994) as well as McAnelly and Cotton (1986) have shown that MCCs commence from afternoon thunderstorms in the western Great Plains that organize and continue to develop at night into MCCs. Physically, this nocturnal preference has been linked to the Low Level Jet (LLJ) (Maddox 1980; Wetzel 1983; Maddox 1983), which enhances warm air advection and the flux of moist, unstable air into the system. Composites from Maddox (1983) confirm that MCCs reach maximum size around local midnight, corresponding with the strongest LLJ, and weaken during the morning hours when the LLJ typically weakens (Fig. 1). In contrast to this widely confirmed characteristic of MCCs, convection on 14 August 2000 organized during the early morning in eastern North Dakota, reached maximum intensity and organization during the day across northern Minnesota and northern Wisconsin, and then slowly weakened during the early morning hours of 15 August in central Wisconsin. -
Oak Lawn Tornado 1967 an Analysis of the Northern Illinois Tornado Outbreak of April 21St, 1967 Oak Lawn History
Oak Lawn Tornado 1967 An analysis of the Northern Illinois Tornado Outbreak of April 21st, 1967 Oak Lawn History • First Established in the 1840s and 1850s • School house first built in 1860 • Immigrants came after the civil war • Post office first established in 1882 • Innovative development plan began in 1927 • Population exponentially grew up to the year of 1967 Path of the Storm • The damage path spanned from Palos, Illinois (about 2-3 miles west/southwest of Oak Lawn) to Lake Michigan. With the worst damage occurring in the Oak Lawn area. Specifically, the corner of 95th street and Southwest Highway • Other places that received Significant damage includes: 89th and Kedzie Avenue 88th and California Avenue Near the Dan Ryan at 83rd Street Timing (All times below are in CST on April 21st, 1967) • 8 AM – Thunderstorms develop around the borders of Iowa, Nebraska, Kansas, and Missouri • 4:45 PM – Cell is first indicated on radar (18 miles west/northwest of Joliet) • 5:15 PM – rotating clouds reported 10 miles north of Joliet • 5:18 PM – Restaurant at the corner of McCarthy Road and 127th Street had their windows blown out • 5:24 PM – Funnel Cloud reported (Touchdown confirmed) • 5:26 PM – Storm continues Northeast and crosses Roberts Road between 101st and 102nd streets • 5:32 PM - Tornado cause worst damage at 95th street and Southwest highway • 5:33 PM – Tornado causes damage to Hometown City Hall • 5:34 PM – Tornado passes grounds of Beverly Hills Country Club • 5:35 PM – Tornado crosses Dan Ryan Expressway and flips over a semi • 5:39 PM – Tornado passes Filtration plant at 78th and Lake Michigan and Dissipates Notable Areas Destroyed •Fairway Supermarket •Sherwood Restaurant •Shoot’s Lynwood Tavern •Suburban Bus Terminal •Airway Trailer Park •Oak Lawn Roller Rink •Plenty More! Pictures to the right were taken BEFORE the twister 52 Total Tornadoes in 6 states (5 EF4’s including the Oak Lawn, Belvidere, and Lake Zurich Tornadoes) Oak Lawn Tornado Blue = EF4 Next several slides summary • The next several slides, I will be going through different parameters. -
A Simple Moisture Advection Model of Specific Humidity
1NOVEMBER 2016 C HADWICK ET AL. 7613 A Simple Moisture Advection Model of Specific Humidity Change over Land in Response to SST Warming ROBIN CHADWICK,PETER GOOD, AND KATE WILLETT Met Office Hadley Centre, Exeter, United Kingdom (Manuscript received 24 March 2016, in final form 25 July 2016) ABSTRACT A simple conceptual model of surface specific humidity change (Dq) over land is described, based on the effect of increased moisture advection from the oceans in response to sea surface temperature (SST) warming. In this model, future q over land is determined by scaling the present-day pattern of land q by the fractional increase in the oceanic moisture source. Simple model estimates agree well with climate model projections of future Dq (mean spatial correlation coefficient 0.87), so Dq over both land and ocean can be viewed primarily as a thermodynamic process controlled by SST warming. Precipitation change (DP) is also affected by Dq, and the new simple model can be included in a decomposition of tropical precipitation change, where it provides increased physical understanding of the processes that drive DP over land. Confidence in the thermodynamic part of extreme precipitation change over land is increased by this improved understanding, and this should scale approximately with Clausius–Clapeyron oceanic q increases under SST warming. Residuals of actual climate model Dq from simple model estimates are often associated with regions of large circulation change, and can be thought of as the ‘‘dynamical’’ part of specific humidity change. The simple model is used to explore intermodel uncertainty in Dq, and there are substantial contributions to uncertainty from both the thermodynamic (simple model) and dynamical (residual) terms. -
P7.1 a Comparative Verification of Two “Cap” Indices in Forecasting Thunderstorms
P7.1 A COMPARATIVE VERIFICATION OF TWO “CAP” INDICES IN FORECASTING THUNDERSTORMS David L. Keller Headquarters Air Force Weather Agency, Offutt AFB, Nebraska 1. INTRODUCTION layer parcels are then sufficiently buoyant to rise to the Level of Free Convection (LFC), resulting in convection The forecasting of non-severe and severe and possibly thunderstorms. In many cases dynamic thunderstorms in the continental United States forcing such as low-level convergence, low-level warm (CONUS) for military customers is the responsibility of advection, or positive vorticity advection provide the Air Force Weather Agency (AFWA) CONUS Severe additional force to mechanically lift boundary layer Weather Operations (CONUS OPS), and of the Storm parcels through the inversion. Prediction Center (SPC) for the civilian government. In the morning hours, one of the biggest Severe weather is defined by both of these challenges in severe weather forecasting is to organizations as the occurrence of a tornado, hail determine not only if, but also where the cap will break larger than 19 mm, wind speed of 25.7 m/s, or wind later in the day. Model forecasts help determine future damage. These agencies produce ‘outlooks’ denoting soundings. Based on the model data, severe storm areas where non-severe and severe thunderstorms are indices can be calculated that help measure the expected. Outlooks are issued for the current day, for predicted dynamic forcing, instability, and the future ‘tomorrow’ and the day following. The ‘day 1’ forecast state of the capping inversion. is normally issued 3 to 5 times per day, the ‘day 2’ and One measure of the cap is the Convective ‘day 3’ forecasts less frequently. -
Thunderstorm Predictors and Their Forecast Skill for the Netherlands
Atmospheric Research 67–68 (2003) 273–299 www.elsevier.com/locate/atmos Thunderstorm predictors and their forecast skill for the Netherlands Alwin J. Haklander, Aarnout Van Delden* Institute for Marine and Atmospheric Sciences, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands Accepted 28 March 2003 Abstract Thirty-two different thunderstorm predictors, derived from rawinsonde observations, have been evaluated specifically for the Netherlands. For each of the 32 thunderstorm predictors, forecast skill as a function of the chosen threshold was determined, based on at least 10280 six-hourly rawinsonde observations at De Bilt. Thunderstorm activity was monitored by the Arrival Time Difference (ATD) lightning detection and location system from the UK Met Office. Confidence was gained in the ATD data by comparing them with hourly surface observations (thunder heard) for 4015 six-hour time intervals and six different detection radii around De Bilt. As an aside, we found that a detection radius of 20 km (the distance up to which thunder can usually be heard) yielded an optimum in the correlation between the observation and the detection of lightning activity. The dichotomous predictand was chosen to be any detected lightning activity within 100 km from De Bilt during the 6 h following a rawinsonde observation. According to the comparison of ATD data with present weather data, 95.5% of the observed thunderstorms at De Bilt were also detected within 100 km. By using verification parameters such as the True Skill Statistic (TSS) and the Heidke Skill Score (Heidke), optimal thresholds and relative forecast skill for all thunderstorm predictors have been evaluated. -
A Study of Morning Radiation Fog Formation
Air Force Institute of Technology AFIT Scholar Theses and Dissertations Student Graduate Works 3-2000 A Study of Morning Radiation Fog Formation Jimmie L. Trigg Jr. Follow this and additional works at: https://scholar.afit.edu/etd Part of the Meteorology Commons Recommended Citation Trigg, Jimmie L. Jr., "A Study of Morning Radiation Fog Formation" (2000). Theses and Dissertations. 4872. https://scholar.afit.edu/etd/4872 This Thesis is brought to you for free and open access by the Student Graduate Works at AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AFIT Scholar. For more information, please contact [email protected]. A STUDY OF MORNING RADIATION FOG FORMATION THESIS Jimmie L. Trigg, Captain, USAF AFIT/GM/ENP/OOM-14 DEPARTMENT OF THE AIR FORCE rv> AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. rv» DUG QUALITY mmMMM) 4 Acknowledgments I would like to take this opportunity to thank the many people who have helped me in this research and preparation of this thesis. First, I must thank the crew in the weather lab; Pete Rahe, Ed Goetz, Tami Parsons, Liz Boll, Lisa Shoemaker, Mike Holmes and Steve Dickerson. Their help in programming and their understanding during my numerous Tourettes Syndrome like outbreaks made the semester manageable. Next, I would like to thank my thesis advisor Major Gary Huffines. Our numerous conversations and his suggestions gave me the right amount of assistance to focus and concentrate on the subject when I needed it. -
Mesoscale Convective Complexes: an Overview by Harold Reynolds a Report Submitted in Conformity with the Requirements for the De
Mesoscale Convective Complexes: An Overview By Harold Reynolds A report submitted in conformity with the requirements for the degree of Master of Science in the University of Toronto © Harold Reynolds 1990 Table of Contents 1. What is a Mesoscale Convective Complex?........................................................................................ 3 2. Why Study Mesoscale Convective Complexes?..................................................................................3 3. The Internal Structure and Life Cycle of an MCC...............................................................................4 3.1 Introduction.................................................................................................................................... 4 3.2 Genesis........................................................................................................................................... 5 3.3 Growth............................................................................................................................................6 3.4 Maturity and Decay........................................................................................................................ 7 3.5 Heat and Moisture Budgets............................................................................................................ 8 4. Precipitation......................................................................................................................................... 8 5. Mesoscale Warm-Core Vortices.......................................................................................................