DOCSLIB.ORG

Propagation Characteristics of Thunderstorms in Southern Germany

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Propagation Characteristics of Thunderstorms in Southern Germany InstitutfurPhysik der Atmosphare Report No. 97 Propagation characteristics of thunderstorms in southern Germany by Martin Hagen, Blasius Bartenschlager, Ullrich Finke I Diese Berichtsserie des Instituts fur Physik der Atmosphare enthalt Veroffentlichungen, die zu einem spateren Zeitpunkt an anderer Stelle erscheinen sollen, sowie spezielle Einzelergebnisse und erganzende Materialien, die von allgemeinem interesse sind. This series of reports of the Institute of Atmopsheric Physics comprises preprints of publications, specific results and complementary material, which may be of a more general interest. Herausgeber Ulrich Schumann Deutsches Zentrum ftir Luft- und Raumfahrt e.V. (DLR) Institut fur Physik der Atmosphare Redaktion Ute Lob Anschrift DLR - Oberpfaffenhofen D-82234 Wessling Germany Telefon +49-8153 28 1797 Telefax +49-8153 28 1841 WWW http://www.op.dlr.de/ipa/ E-Mail [email protected] Oberpfaffenhofen Mai 1998 ISSN 0943-4771 DISCLAIMER Portions of this document may be illegible electronic image products. Images are produced from the best available original document. Institut fur Physik der Atmosphare Report No. 97 Propagation characteristics of thunderstorms in southern Germany by Martin Hagen, Blasius Bartenschlager, Ullrich Finke * DLR Propagation characteristics of thunderstorms in southern Germany M. Hagen, B. Bartenschlager, U. Finke, Deutsches Zentrumjur Luft- und Raumfahrt, Institutfur Physikder Atmosphare, Oberpfaffenhofen, 82234 Wefiling, Germany Paper submitted to Meteorological Applications The propagation of thunderstorms in southern Germany was investigated. The thunderstorms were observed by a lightning position system duringthe summer months of the years 1992 to 1996. On average every second day thunderstorms were observed anywhere in southern Germany. In general thunderstormsapproach from westerly and south-westerly directions. The average speed is 13 m/s. No significant relation between the occurrence of thunderstormsand the large scale synoptic pattern described by the Grosswetterlagen (large scale weather pattern) was found. Thunderstorms were observed during almost all Grosswetterlagen. The reduction to 8 weather pattern based on the low- level flow in southern Germany showed that thunderstorms are likely when the flowhas westerly di­ rections (43%) or easterly directions (20%). Three distinct groups of differentlightning patterns could be identified; stationary, moving thunderstorms and thunderstorm lines. The convective avail­ able potential energy (CAPE) and the wind shear were retrieved from the radio soundings from Munchen and Stuttgart. On average CAPE was 583 J/kgfor stationary, 701 J/kgfor moving thunder­ storms, and 876 J/kgfor thunderstorm lines. The average bulk Richardson numbers are 152, 80 and 52 for stationary, moving thunderstorms and thunderstorm lines, respectively. The steering level was found to be at about 3 and 6 km m.s.l. However, it should be noted, thatin most cases the soundings do not completely describe the local environmentof thunderstorms, since radio soundingsare only available twice a day. 1 Introduction for thunderstorms in the state of maturity. By means of a phenomenological classification based on different patterns and structures of the spatial lightning distri­ During summer thunderstorms are a frequent weather bution the thunderstorms have been divided into three phenomena in southern Europe. They have an essential types. These phenomenological types of thunderstorms contribution to the total precipitation in southern Ger­ then have been related to environmental and synoptic many. Thunderstorms are connected with lightning conditions. strikes, heavy precipitation, hail and strong turbulence, thus having a considerable potential of endangering Only a few related studies for Central Europe are and damage. For that reason more knowledge of the known. The analysis by Pelz (1984) is based on syn­ development and motion of thunderstorms is of great optic observations (1893 until 1907) and gives the interest and represents a central problem in nowcasting spatial distribution of thunderstorm days in Germany. and short range forecast. More recent studies have been performed with radar data by Holler (1994) and by Finke and Hauf The object of this paper is to show how the propaga­ (1996a+b) using lightning observations. Houze et al. tion characteristics and the organisation of thunder­ (1993) and Schiesser et al. (1995) investigated the storms in southern Germany is related to environ­ mesoscale structure of severe precipitation systems in mental and synoptic conditions. For this purpose a Switzerland. great number of thunderstorm days (1992-96) in southern Germany have been investigated. A lightning Holler (1994) showed how the mesoscale organisation location system operated by the Badenwerk AG and of thunderstorms in southern Germany is related to the the Bayern werk AG in southern Germany has been occurrence of hail. Based on radar observations thun­ used for the determination and classification of thun­ derstorms where classified as single cells, multicell derstorm days. Lightning is an unambiguous indicator storms and supercell storms. Their mesoscale organi ­ 1 sation was classified as isolated storms, clusters, line- 2 Types of thunderstorms and envi­ oriented storms and squall lines. Further details will be ronmental conditions given in Section 2. The analysis of polarimetric radar data showed that at 61% of the thunderstorm days hail was observed. The development of specific storm characteristics such as the organisation of the cells, life cycle, or propaga­ Finke and Hauf (1996 a) statistically evaluated the tion velocity depends mainly on environmental condi ­ tracks of moving thunderstorms in southern Germany tions. This environment is described by the synoptic by observations from a lightning network for a 3-year state of the atmosphere and, more detailed, by the time period (1992 - 1994). According to the lightning vertical profile of the wind, temperature and humidity. patterns the thunderstorms have been divided into three classes. More details can be found in Section 3. Single-cell storms were observed at 37%, storm tracks 2.1 Organisation of thunderstorms at 57% and fronts at 6% of the thunderstorm days, respectively. A frequency distribution of storm tracks Holler (1994) summarised the types of thunderstorms shows that for 56% of all cases the storms approach in southern Germany based on the storm scale and from south-west or west. The mean velocity is 47 mesoscale organisation. On the storm scale three basic km/h. The most frequently observed lifetime of storms types can be identified (after Foote, 1985): is 4 hours. Storm tracks longer than 250 km can be found on an average of 18 days a year. - Single cells, where the complete cycle of pre­ cipitation development and fallout takes place in Characteristic properties of thunderstorms like the life one cell within roughly half an hour. cycle and the type of organisation principally depend on environmental conditions. Numerical studies by - Multicell storms. All stages of development are Weisman and Klemp (1982 and 1984) show typical coexisting each one forming a part of the same values of environmental buoyancy and wind shear for storm system. Those systems can last for a few different types of thunderstorm organisation. The bulk hours. Richardson number was shown to be a suited indicator for the storm type: low values are observed in the - Supercell storms. The storm is formed by a large surrounding of supercells, higher values are observed quasi-stationary cell. All the different stages take with multicell storms. place in the same cell but at different locations. Supercell storms can last up to 12 hours. More recently thunderstorms in Switzerland have been investigated and environmental parameters have been This classification requires knowledge of the dynamic calculated to separate heavy hail thunderstorms from and microphysic structure of the storm. Alternatively, other thunderstorms. It was found that at thunderstorm phenomenological approaches classify the storms on days with stronger hail damage the mean value of their appearance as seen by an observation system. CAPE (convective available potential energy, see Based on the mesoscale shape of radar echoes the Section 2) is 656 J/kg and for the most heaviest hail ­ following mesoscale organisations are observed in storms the mean value is 876 J/kg (Schiesser et al., southern Germany (Holler, 1994; after Houze et al., 1997). 1990): In the Central-European region almost no attempt has - Isolated storms. Thunderstorms exist isolated been undergone to investigate the great variety of and are not embedded in common reflectivity known indices which are used to describe the prob­ contours. ability of thunderstorm occurrence. However, Huntrie- ser et al. (1997) tested several indices for their useful­ - Clusters or complexes of storms. Thunderstorms ness in Switzerland. Their results show that CAPE is are closely grouped together. A cluster does not one of the successful indices to be used for forecasting have a preferred direction of alignment. thunderstorms. - Line-oriented storms. Isolated storms or storms The classification of thunderstorms, their initiation, within a cluster are aligned along lines. and the environmental conditions are outlined in Sec­ tion 2. Section 3 describes the data base and the proc­ - Squall lines. Special form of line-oriented sys­ essing of the lightning data, and Section 4 gives the tems. Squall lines are often characterised
Load more

Recommended publications
  • Laboratory Studies of Turbulent Mixing J.A
    Laboratory Studies of Turbulent Mixing J.A. Whitehead Woods Hole Oceanographic Institution, Woods Hole, MA, USA Laboratory measurements are required to determine the rates of turbulent mixing and dissipation within flows of stratified fluid. Rates based on other methods (theory, numerical approaches, and direct ocean measurements) require models based on assumptions that are suggested, but not thoroughly verified in the laboratory. An exception to all this is recently provided by direct numerical simulations (DNS) mentioned near the end of this article. Experiments have been conducted with many different devices. Results span a wide range of gradient or bulk Richardson number and more limited ranges of Reynolds number and Schmidt number, which are the three most relevant dimensionless numbers. Both layered and continuously stratified flows have been investigated, and velocity profiles include smooth ones, jets, and clusters of eddies from stirrers or grids. The dependence of dissipation through almost all ranges of Richardson number is extensively documented. The buoyancy flux ratio is the turbulent kinetic energy loss from raising the potential energy of the strata to loss of kinetic energy by viscous dissipation. It rises from zero at small Richardson number to values of about 0.1 at Richardson number equal to 1, and then falls off for greater values. At Richardson number greater than 1, a wide range of power laws spanning the range from −0.5 to −1.5 are found to fit data for different experiments. Considerable layering is found at larger values, which causes flux clustering and may explain both the relatively large scatter in the data as well as the wide range of proposed power laws.
    [Show full text]
  • Chapter 7.0 – Determining Wind Direction Section 7.1 Overview Of
    Chapter 7.0 – Determining Wind Direction Section 7.1 Overview of Wind Direction The wind direction is a measure or indication of where the air movement originated from. The wind direction can be measured through the use of a wind sock, wind vane, or a light object attached to a pole and string (example: A ping pong ball attached to a string which is tied to a stick). Wind direction is generally reported in either Azimuth degrees or Cardinal direction. Azimuth uses a circle with the northern most position indicating 0 degrees. The Cardinal direction system gives an Azimuth degree value a name. For example, 180 degrees is South(S) and 270 degrees is West (W) (See Figure 18 - A basic compass rose). Figure 18 - A basic compass rose Section 7.2 Overview of the homemade Wind Vane The wind vane used in this design was a homemade wind vane using a miniature absolute magnetic shaft encoder. The encoder chosen for use was the MA3 produced by US Digital. The purpose for choosing this specific encoder in regards to this design was that the MA3 met four (4) critical objectives. First, the MA3 was the correct size for the application. Second, the MA3 uses an analog output of 0 volts to 5 volts with respect to the current positions (See Figure 19 – MA3 Output behaviour) Figure 19 – MA3 Output behaviour Third, the MA3 uses a 5 volt input. This was a major consideration when choosing an encoder as a 5 volt input allowed for a more simple integration. Fourth, and final, the MA3 met the requirements of being able to function in an adverse environment, having an operational temperature of -40 ºC to +125 ºC.
    [Show full text]
  • NWS Unified Surface Analysis Manual
    Unified Surface Analysis Manual Weather Prediction Center Ocean Prediction Center National Hurricane Center Honolulu Forecast Office November 21, 2013 Table of Contents Chapter 1: Surface Analysis – Its History at the Analysis Centers…………….3 Chapter 2: Datasets available for creation of the Unified Analysis………...…..5 Chapter 3: The Unified Surface Analysis and related features.……….……….19 Chapter 4: Creation/Merging of the Unified Surface Analysis………….……..24 Chapter 5: Bibliography………………………………………………….…….30 Appendix A: Unified Graphics Legend showing Ocean Center symbols.….…33 2 Chapter 1: Surface Analysis – Its History at the Analysis Centers 1. INTRODUCTION Since 1942, surface analyses produced by several different offices within the U.S. Weather Bureau (USWB) and the National Oceanic and Atmospheric Administration’s (NOAA’s) National Weather Service (NWS) were generally based on the Norwegian Cyclone Model (Bjerknes 1919) over land, and in recent decades, the Shapiro-Keyser Model over the mid-latitudes of the ocean. The graphic below shows a typical evolution according to both models of cyclone development. Conceptual models of cyclone evolution showing lower-tropospheric (e.g., 850-hPa) geopotential height and fronts (top), and lower-tropospheric potential temperature (bottom). (a) Norwegian cyclone model: (I) incipient frontal cyclone, (II) and (III) narrowing warm sector, (IV) occlusion; (b) Shapiro–Keyser cyclone model: (I) incipient frontal cyclone, (II) frontal fracture, (III) frontal T-bone and bent-back front, (IV) frontal T-bone and warm seclusion. Panel (b) is adapted from Shapiro and Keyser (1990) , their FIG. 10.27 ) to enhance the zonal elongation of the cyclone and fronts and to reflect the continued existence of the frontal T-bone in stage IV.
    [Show full text]
  • Boundary Layer Verification
    Boundary Layer Verification ECMWF training course April 2015 Maike Ahlgrimm Aim of this lecture • To give an overview over strategies for boundary layer evaluation • By the end of this session you should be able to: – Identify data sources and products suitable for BL verification – Recognize the strengths and limitations of the verification strategies discussed – Choose a suitable verification method to investigate model errors in boundary layer height, transport and cloudiness. smog over NYC Overview • General strategy for process-oriented model evaluation • What does the BL parameterization do? • Broad categories of BL parameterizations • Which aspects of the BL can we evaluate? – What does each aspect tell us about the BL? • What observations are available – What are the observations’ advantages and limitations? • Examples – Clear convective BL – Cloud topped convective BL – Stable BL Basic strategy for model evaluation and improvement: Observations Identify discrepancy Model Output Figure out source of model error Improve parameterization When and where does error occur? Which parameterization(s) is/are involved? What does the BL parameterization do? Attempts to integrate Turbulence transports effects of small scale temperature, moisture and turbulent motion on momentum (+tracers). prognostic variables at grid resolution. Stull 1988 Ultimate goal: good model forecast and realistic BL Broad categories of BL parameterizations Unified BL schemes Specialized BL scheme •Attempt to integrate BL (and •One parameterization for each shallow cloud) effects in one discrete BL type scheme to allow seamless transition •Simplifies parameterization for •Often statistical schemes (i.e. each type, parameterization for making explicit assumptions about each type ideally suited PDFs of modelled variables) using •Limitation: must identify BL type moist-conserved variables reliably, is noisy (lots of if •Limitation: May not work well for statements) mixed-phase or ice •Example: Met-Office (Lock et al.
    [Show full text]
  • On the Computation of Planetary Boundary-Layer Height Using the Bulk Richardson Number Method
    Geosci. Model Dev., 7, 2599–2611, 2014 www.geosci-model-dev.net/7/2599/2014/ doi:10.5194/gmd-7-2599-2014 © Author(s) 2014. CC Attribution 3.0 License. On the computation of planetary boundary-layer height using the bulk Richardson number method Y. Zhang1, Z. Gao2, D. Li3, Y. Li1, N. Zhang4, X. Zhao1, and J. Chen1,5 1International Center for Ecology, Meteorology & Environment, Jiangsu Key Laboratory of Agricultural Meteorology, College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China 2State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 3Program of Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ 08540, USA 4School of Atmospheric Sciences, Nanjing University, Nanjing, 210093, China 5Department of Geography, Michigan State University, East Lansing, MI 48824, USA Correspondence to: Z. Gao ([email protected]) Received: 15 March 2014 – Published in Geosci. Model Dev. Discuss.: 24 June 2014 Revised: 12 September 2014 – Accepted: 22 September 2014 – Published: 10 November 2014 Abstract. Experimental data from four field campaigns are 1 Introduction used to explore the variability of the bulk Richardson num- ber of the entire planetary boundary layer (PBL), Ribc, which The planetary boundary layer (PBL), or the atmospheric is a key parameter for calculating the PBL height (PBLH) boundary layer, is the lowest part of the atmosphere that is in numerical weather and climate models with the bulk directly influenced by earth’s surface and has significant im- Richardson number method. First, the PBLHs of three differ- pacts on weather, climate, and the hydrologic cycle (Stull, ent thermally stratified boundary layers (i.e., strongly stable 1988; Garratt, 1992; Seidel et al., 2010).
    [Show full text]
  • Impact of Cloud Analysis on Numerical Weather Prediction in the Galician Region of Spain
    Impact of Cloud Analysis on Numerical Weather Prediction in the Galician Region of Spain M. J. SOUTO, C. F. BALSEIRO AND V. P…REZ-MU—UZURI Group of Nonlinear Physics, Faculty of Physics, University of Santiago de Compostela, Santiago de Compostela, Spain Ming Xue University of Oklahoma, School of Meteorology, and CAPS Oklahoma, USA Keith BREWSTER Center for Analysis and Prediction of Storms, Oklahoma, USA April, 2001 Revised December, 2001 Corresponding author address: Dra. M. J. Souto, Group of Nonlinear Physics Faculty of Physics, University of Santiago de Compostela E-15706, Santiago de Compostela, Spain e-mail: [email protected] ABSTRACT The Advanced Regional Prediction System (ARPS) is applied to operational numerical weather forecast in Galicia, northwest Spain. A 72-hour forecast at a 10-km horizontal resolution is produced dta for the region. Located on the northwest coast of Spain and influenced by the Atlantic weather systems, Galicia has a high percentage (almost 50%) of rainy days per year. For these reasons, the precipitation processes and the initialization of moisture and cloud fields are very important. Even though the ARPS model has a sophisticated data analysis system (ADAS) that includes a 3D cloud analysis package, due to operational constraint, our current forecast starts from 12-hour forecast of the NCEP AVN model. Still, procedures from the ADAS cloud analysis are being used to construct the cloud fields based on AVN data, and then applied to initialize the microphysical variables in ARPS. Comparisons of the ARPS predictions with local observations show that ARPS can predict quite well both the daily total precipitation and its spatial distribution.
    [Show full text]
  • Black Forest Black Forest
    Black Forest Black Forest A BCDEFGH 1 1 2 2 3 3 4 4 5 5 6 6 All locations and regions, listed alphabetically 7 7 PLAN PAGE PLAN PAGE Impressum Black Forest 4-15 St. BlasierLand D12/E13 29 (Dachsberg, Häusern, Höchenschwand, Ibach, St.Blasien- Herausgeber Cities & villages 22-39 Menzenschwand, Weilheim) Bad Bellingen A12 35 Todtmoos C12 39 Bad Liebenzell H3 31 Schwarzwald Tourismus GmbH Wolfach/Oberwolfach E7 39 8 8 Baden-Baden E3 35 Ludwigstraße 23 Baiersbronn E/F6 35 Zweitälerland D8/C9 39 79104 Freiburg Blumberg F/G11 36 (Biederbach, Elzach, Gutach im Breisgau, Simonswald, Tel.: + 49 (0) 761.896460 Bühl-Bühlertal D/E4 36 Waldkirch, Winden im Elztal) Fax: + 49 (0) 761.8964670 Dornstetten F6 36 [email protected] Donaueschingen und Hüfingen F10 22 www.schwarzwald-tourismus.info Enztal F/G3 32 All forms of accommodation 9 9 (Bad Wildbad, Enzklösterle, Höfen) Hotels and guesthouses 40-60 Geschäftsführer: Christopher Krull Ferienland im Schwarzwald E9 37 Apartments and holiday rentals 46, 61-64 (Furtwangen, Schönwald, Schonach, St. Georgen, Triberg) Projektleitung: Jochen Laufer, Sascha Hotz/Berg- Freiburg C10 37 werk Marketing Freudenstadt und Lossburg F6 23 Redaktion: STG 10 10 Hochschwarzwald D/E10/11 24 (Breitnau, Eisenbach, Feldberg, Friedenweiler, Fotonachweis: Hinterzarten, Lenzkirch, Löffingen, St. Märgen, St. Peter, Düpper, Eberle/qu-int, Hotel Auerhahn Schluch- Schluchsee,Titisee-Neustadt) More information and reservations: see, Raach, Spiegelhalter, Erdenbrink, U. Klumpp Hornberg E8 37 (S.6), Archiv der STG sowie der
    [Show full text]
  • ESSENTIALS of METEOROLOGY (7Th Ed.) GLOSSARY
    ESSENTIALS OF METEOROLOGY (7th ed.) GLOSSARY Chapter 1 Aerosols Tiny suspended solid particles (dust, smoke, etc.) or liquid droplets that enter the atmosphere from either natural or human (anthropogenic) sources, such as the burning of fossil fuels. Sulfur-containing fossil fuels, such as coal, produce sulfate aerosols. Air density The ratio of the mass of a substance to the volume occupied by it. Air density is usually expressed as g/cm3 or kg/m3. Also See Density. Air pressure The pressure exerted by the mass of air above a given point, usually expressed in millibars (mb), inches of (atmospheric mercury (Hg) or in hectopascals (hPa). pressure) Atmosphere The envelope of gases that surround a planet and are held to it by the planet's gravitational attraction. The earth's atmosphere is mainly nitrogen and oxygen. Carbon dioxide (CO2) A colorless, odorless gas whose concentration is about 0.039 percent (390 ppm) in a volume of air near sea level. It is a selective absorber of infrared radiation and, consequently, it is important in the earth's atmospheric greenhouse effect. Solid CO2 is called dry ice. Climate The accumulation of daily and seasonal weather events over a long period of time. Front The transition zone between two distinct air masses. Hurricane A tropical cyclone having winds in excess of 64 knots (74 mi/hr). Ionosphere An electrified region of the upper atmosphere where fairly large concentrations of ions and free electrons exist. Lapse rate The rate at which an atmospheric variable (usually temperature) decreases with height. (See Environmental lapse rate.) Mesosphere The atmospheric layer between the stratosphere and the thermosphere.
    [Show full text]
  • 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
    [Show full text]
  • NOAA Technical Memorandum NWS WR-221 UTILIZATION of the BULK RICHARDSON NUMBER, HELICITY and SOUNDING MODIFICATION in the ASSESS
    NOAA Technical Memorandum NWS WR-221 UTILIZATION OF THE BULK RICHARDSON NUMBER, HELICITY AND SOUNDING MODIFICATION IN THE ASSESSMENT OF THE SEVERE CONVECTIVE STORMS OF 3 AUGUST 1992 ~ \ Eric C. Evenson Weather Service Forecast Office Great Falls, Montana November 1993 u.s. DEPARTMENT OF I National Oceanic and National Weather COMMERCE Atmospheric Administration I Service 75 A Study of the Low Level Jet Stream of the San Joaqnin Valley. Ronald A Wlllis and NOAA TECHNICAL MEMORANDA Philip Williams, Jr., May 1972. (COM 72 10707) National Weather Service, Western Region Subseries 76 Monthly Climatological Charta of the Behavior of Fog and Low Stratus at Los Angeles International Airport. Donald M. Gales, July 1972. (COM 72 11140) The National Weather Service (NWS) Western Region (WR) Subseries provi~es an informal 77 A Study of Radar Echo Distribution in Arizona During July and August. John E. Hales, Jr.. medium for the documentation and quick dissemination of results not. appropnate, or not ~et July 1972. (COM 72 11136) ready, for formal publication. The series is used to report. o'! work '-? progreas, to des~ 78 Forecasting Precipitation at Bakersfield, California, Using Preasure Gradient Vectors. Earl technical procedures and practices, or. to relate progre_as ~ a limited. audience. These Techrucal T. Riddiough, July 1972. (COM 72 11146) Memoranda will report on investigations devoted primarily to regtonal and local problems of 79 Climate of Stockton, California. Robert C. Nelson, July 1972. (COM 72 10920) interest mainly to penionnel, and hence will not be widely distributed. 60 Estimation of Number of Days Above or Below Selected Temperatures. Clarence M.
    [Show full text]
  • Germany (Territory Under Allied Occupation, 1945-1955 : U.S
    http://oac.cdlib.org/findaid/ark:/13030/kt0g5030jq No online items Inventory of the Germany (Territory under Allied occupation, 1945-1955 : U.S. Zone) Office of Military Government miscellaneous records Finding aid prepared by Lyalya Kharitonova Hoover Institution Library and Archives © 2008 434 Galvez Mall Stanford University Stanford, CA 94305-6003 [email protected] URL: http://www.hoover.org/library-and-archives 80197 1 Title: Germany (Territory under Allied occupation, 1945-1955 : U.S. Zone) Office of Military Government miscellaneous records Date (inclusive): 1944-1950 Collection Number: 80197 Contributing Institution: Hoover Institution Library and Archives Language of Material: In English and German Physical Description: 14 manuscript boxes(5.6 Linear Feet) Abstract: Correspondence, reports, memoranda, statistics, indexes, laws, proclamations, press releases, and bulletins, relating to American administration of occupied Germany after World War II, and especially to civilian relief, economic conditions, housing, and denazification. Creator: Germany (Territory under Allied occupation, 1945-1955 : U.S. Zone). Office of Military Government Hoover Institution Library & Archives Access The collection is open for research; materials must be requested at least two business days in advance of intended use. Publication Rights For copyright status, please contact the Hoover Institution Library & Archives. Acquisition Information Acquired by the Hoover Institution Library & Archives in 1980. Preferred Citation [Identification of item], Germany (Territory under Allied occupation, 1945-1955 : U.S. Zone) Office of Military Government miscellaneous records, [Box no., Folder no. or title], Hoover Institution Library & Archives. Biographical/Historical Note The Allied powers who defeated Nazi Germany in World War II divided the country west of the Oder-Neisse line into four occupation zones for administrative purposes during the period 1945-1949.
    [Show full text]
  • The Effect of Stable Thermal Stratification on Turbulent Boundary
    The effect of stable thermal stratifcation on turbulent boundary layer statistics O.Williams, T. Hohman, T. Van Buren, E. Bou-Zeid and A. J. Smits May 22, 2019 Abstract The effects of stable thermal stratifcation on turbulent boundary layers are ex- perimentally investigated for smooth and rough walls. Turbulent stresses for weak to moderate stability are seen to scale with the wall-shear stress compensated for changes in fuid density in the same manner as done for compressible fows, sug- gesting little change in turbulent structure within this regime. At higher levels of stratifcation turbulence no longer scales with the wall shear stress and turbu- lent production by mean shear collapses, but without the preferential damping of near-wall motions observed in previous studies. We suggest that the weakly sta- ble and strongly stable (collapsed) regimes are delineated by the point where the turbulence no longer scales with the local wall shear stress, a signifcant departure from previous defnitions. The critical stratifcation separating these two regimes closely follows the linear stability analysis of Schlichting (1935) [Schlichting, Hauptaufs¨atze. Turbulenz bei W¨armeschichtung, ZAMM-J. of App. Math. and Mech., vol 15, 1935 ] for both smooth and rough surfaces, indicating that a good predictor of critical stratifcation is the gradient Richardson number evaluated at the wall. Wall-normal and shear stresses follow atmospheric trends in the local gradient Richardson number scaling of Sorbjan (2010) [Sorbjan, Gradient-based scales and similarity laws in the stable boundary layer, Q.J.R. Meteorological Soc., vol 136, 2010], suggesting that much can be learned about stratifed atmo- spheric fows from the study of laboratory scale boundary layers at relatively low Reynolds numbers.
    [Show full text]