Sample records for summer convective storms

  1. Mesoscale aspects of convective storms

    NASA Technical Reports Server (NTRS)

    Fujita, T. T.

    1981-01-01

    The structure, evolution and mechanisms of mesoscale convective disturbances are reviewed and observation techniques for "nowcasting" their nature are discussed. A generalized mesometeorological scale is given, classifying both low and high pressure systems. Mesoscale storms are shown often to induce strong winds, but their wind speeds are significantly less than those accompanied by submesoscale disturbances, such as tornadoes, downbursts, and microbursts. Mesoscale convective complexes, severe storm wakes, and flash floods are considered. The understanding of the evolution of supercells is essential for improving nowcasting capabilities and a very accurate combination of radar and satellite measurements is required.

  2. Convective storms in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Sánchez-Lavega, A.

    2013-05-01

    The atmospheres of the planets in the Solar System have different physical properties that in some cases can be considered as extreme when compared with our own planet's more familiar atmosphere. From the tenuous and cold atmosphere of Mars to the dense and warm atmosphere of Venus in the case of the terrestrial planets, to the gigantic atmospheres of the outer planets, or the nitrogen and methane atmosphere of Saturn's moon Titan, we can find a large variety of physical environments. The comparative study of these atmospheres provides a better understanding of the physics of a geophysical fluid. In many of these worlds convective storms of different intensity appear. They are analogous to terrestrial atmospheres fed by the release of latent heat when one of the gases in the atmosphere condenses and they are therefore called moist convective storms. In many of these planets they can produce severe meteorological phenomena and by studying them in a comparative way we can aspire to get a further insight in the dynamics of these atmospheres even beyond the scope of moist convection. A classical example is the structure of the complex systems of winds in the giant planets Jupiter and Saturn. These winds are zonal and alternate in latitude but their deep structure is not accessible to direct observation. However the behaviour of large--scale convective storms vertically extending over the "weather layer" allows to study the buried roots of these winds. Another interesting atmosphere with a rather different structure of convection is Titan, a world where methane is close to its triple point in the atmosphere and can condense in bright clouds with large precipitation fluxes that may model part of the orography of the surface making Titan a world with a methane cycle similar to the hydrological cycle of Earth's atmosphere.

  3. Principles of Convection III: Shear and Convective Storms

    NSDL National Science Digital Library

    COMET

    2003-11-18

    This module discusses the role of wind shear in the structure and evolution of convective storms. Using the concept of horizontal vorticity, the module demonstrates how shear enhances uplift, leading to longer-lived supercell and multicell storms. The module also explores the role of shear in the development of mesoscale convective systems, including bow echoes and squall lines. Most of the material in this module previously appeared in the COMET modules developed with Dr. Morris Weisman. This version includes a concise summary for quick reference and a final exam to test your knowledge. The module comes with audio narration, rich graphics, and a companion print version.

  4. A Convective Storm Matrix: Buoyancy/Shear Dependencies

    NSDL National Science Digital Library

    COMET

    2003-04-09

    In order to help forecasters build a strategy for anticipating convective storm structures, their evolution, and the potential for severe weather, A Convective Storm Matrix provides learners the opportunity for extensive exploration of the relationship between a storm's environment and its structure. The matrix is composed of 54 four-dimensional numerical simulations based on the interactions of 16 different hodographs and 4 thermodynamic profiles. By comparing animated displays of these simulations, learners are able to discern the influences of varying buoyancy and vertical wind shear profiles on storm structure and evolution. A series of questions guides the exploration and helps to reveal key storm/environment relationships evident in the matrix. A synopsis of the physical processes that control storm structure, as well as the current conceptual models of key convective storms types, is included for reference. Subject matter expects for A Convective Storm Matrix: Buoyancy/Shear Dependencies include Mr. Steve Keighton, Mr. Ed Szoke, and Dr. Morris Weisman. Note: This module was originally published on CD-ROM in March 1996 (v1.1) and re-released in 2001 as v1.3 for Microsoft Windows users only. CD-ROM version 1.3 works fairly well with Windows 98/ME/NT4/2000 but has reported to be problematic with Windows XP. Users of version 1.1 should obtain the patch located at http://www.comet.ucar.edu/help/ModuleSupport/matrix_problem.htm or use the new, Web-based module.

  5. A parameterization of convective dust storms for models with mass-flux convection schemes

    NASA Astrophysics Data System (ADS)

    Pantillon, Florian; Knippertz, Peter; Marsham, John; Birch, Cathryn

    2015-04-01

    Cold pool outflows, generated by downdrafts from moist convection, can generate strong winds and therefore uplift of mineral dust. These so-called ``haboob'' convective dust storms occur over all major dust source areas worldwide and contribute substantially to emissions in northern Africa, the world's largest source. Most large-scale models lack convective dust storms, because they do not resolve moist convection, relying instead on convection schemes. We suggest a parameterization of convective dust storms to account for their contribution in such large-scale models. The parameterization is based on a simple conceptual model, in which the downdraft mass flux from the convection scheme spreads out radially in a cylindrical cold pool. The parameterization is tested with a set of Unified Model runs for June and July 2006 over West Africa. It is calibrated with a convection-permitting run, and applied to a convection-parameterized run. The parameterization successfully produces the extensive area of dust-generating winds from cold pool outflows over the southern Sahara. However, this area extends farther to the east and dust generating winds occur earlier in the day than in the convection-permitting run. These biases are due to biases in the convection scheme. It is found that the location and timing of dust-generating winds are weakly sensitive to the parameters of the conceptual model. The results demonstrate that a simple parameterization has the potential to correct a major and long-standing limitation in global dust models.

  6. Critical grid size for simulating convective storms: A case study of the Del City supercell storm

    NASA Astrophysics Data System (ADS)

    Noda, A.; Niino, H.

    2003-08-01

    The dependence of a numerically-simulated `Del City' supercell storm on grid size is studied. A reference run with the grid size of 0.5 km successfully reproduces the supercell as demonstrated in the previous studies. In this sensitivity study, the grid size is varied from 1.0 km to 3.0 km with an interval of 100 m. When the grid size is less than 2.5 km, the storm evolves in a manner qualitatively similar to the reference run. When it is larger than 2.5 km, however, the evolution of the storm changes drastically because of an insufficient estimation of the shear-induced dynamic pressure. The present ``critical grid size'' is much smaller than that expected from the former sensitivity studies. Thus, one has to be more careful in choosing the grid size when performing a prediction of mesoscale convective systems, the behavior of which depends strongly on the behavior of individual meso-?-scale convective storms.

  7. Characteristics of Extreme Summer Convection over equatorial America and Africa

    NASA Astrophysics Data System (ADS)

    Zuluaga, M. D.; Houze, R.

    2013-12-01

    Fourteen years of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) version 7 data for June-August show the temporal and spatial characteristics of extreme convection over equatorial regions of the American and African continents. We identify three types of extreme systems: storms with deep convective cores (contiguous convective 40 dBZ echoes extending ?10 km in height), storms with wide convective cores (contiguous convective 40 dBZ echoes with areas >1,000 km2) and storms with broad stratiform regions (stratiform echo >50,000 km2). European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis is used to describe the environmental conditions around these forms of extreme convection. Storms with deep convective cores occur mainly over land: in the equatorial Americas, maximum occurrence is in western Mexico, Northern Colombia and Venezuela; in Africa, the region of maximum occurrence is a broad zone enclosing the central and west Sudanian Savanna, south of the Sahel region. Storms with wide convective radar echoes occur in these same general locations. In the American sector, storms with broad stratiform precipitation regions (typifying robust mesoscale convective systems) occur mainly over the eastern tropical Pacific Ocean and the Colombia-Panama bight. In the African sector, storms with broad stratiform precipitation areas occur primarily over the eastern tropical Atlantic Ocean near the coast of West Africa. ECMWF reanalyses show how the regions of extreme deep convection associated with both continents are located mainly in regions affected by diurnal heating and influenced by atmospheric jets in regions with strong humidity gradients. Composite analysis of the synoptic conditions leading to the three forms of extreme convection provides insights into the forcing mechanisms in which these systems occur. These analyses show how the monsoonal flow directed towards the Andes slopes is mainly what concentrates the occurrence of extreme cases over tropical America. Over Africa the monsoon is also important in modulating the occurrence of extreme convection; however, diurnal heating and the passage of African Easterly Waves are of primary importance in distributing the extreme convection zonally across the tropical African savannas.

  8. European climatology of severe convective storm environmental parameters: A test for significant tornado events

    E-print Network

    Doswell III, Charles A.

    European climatology of severe convective storm environmental parameters: A test for significant with severe convective storms has been constructed for Europe. This involves using the reanalysis data base from ERA-40 for the period 1971­2000 and calculating monthly means, variability range and extremes

  9. Empirical reconstruction of storm-time steady magnetospheric convection events

    NASA Astrophysics Data System (ADS)

    Stephens, G. K.; Sitnov, M. I.; Kissinger, J.; Tsyganenko, N. A.; McPherron, R. L.; Korth, H.; Anderson, B. J.

    2013-12-01

    We investigate the storm-scale morphology of the magnetospheric magnetic field as well as underlying distributions of electric currents, equatorial plasma pressure and entropy for four Steady Magnetospheric Convection (SMC) events that occurred during the May 2000 and October 2011 magnetic storms. The analysis is made using the empirical geomagnetic field model TS07D, in which the structure of equatorial currents is not predefined and it is dictated by data. The model also combines the strengths of statistical and event-oriented approaches in mining data for the reconstruction of the magnetic field. The formation of a near-Earth minimum of the equatorial magnetic field in the midnight sector is inferred from data without ad hoc assumptions of a special current system postulated in earlier empirical reconstructions. In addition, a new SMC class is discovered where the minimum equatorial field is substantially larger and located closer to Earth. The magnetic field tailward of the minimum is also much larger, and the corresponding region of accumulated magnetic flux may occupy a very short tail region. The equatorial current and plasma pressure are found to be strongly enhanced far beyond geosynchronous orbit and in a broad local time interval covering the whole nightside region. This picture is consistent with independent recent statistical studies of the SMC pressure distributions, global MHD and kinetic RCM-E simulations. Distributions of the flux tube volume and entropy inferred from data reveal different mechanisms of the magnetotail convection crisis resolution for two classes of SMC events.

  10. Empirical reconstruction of storm time steady magnetospheric convection events

    NASA Astrophysics Data System (ADS)

    Stephens, G. K.; Sitnov, M. I.; Kissinger, J.; Tsyganenko, N. A.; McPherron, R. L.; Korth, H.; Anderson, B. J.

    2013-10-01

    We investigate the storm-scale morphology of the magnetospheric magnetic field as well as underlying distributions of electric currents, equatorial plasma pressure, and entropy for four steady magnetospheric convection (SMC) events that occurred during the May 2000 and October 2011 magnetic storms. The analysis is made using the empirical geomagnetic field model TS07D, in which the structure of equatorial currents is not predefined and it is dictated by data. The model also combines the strengths of statistical and event-oriented approaches in mining data for the reconstruction of the magnetic field. The formation of a near-Earth minimum of the equatorial magnetic field in the midnight sector is inferred from data without ad hoc assumptions of a special current system postulated in earlier empirical reconstructions. In addition, a new SMC class is discovered where the minimum equatorial field is substantially larger and located closer to Earth. The magnetic field tailward of the minimum is also much larger, and the corresponding area of accumulated magnetic flux may occupy a very short tail region. The equatorial current and plasma pressure are found to be strongly enhanced far beyond geosynchronous orbit and in a broad local time interval covering the whole nightside region. This picture is consistent with independent recent statistical studies of the SMC pressure distributions, global MHD, and kinetic Rice Convection Model-Equilibrium (RCM-E) simulations. Distributions of the flux tube volume and entropy inferred from data reveal different mechanisms of the magnetotail convection crisis resolution for two classes of SMC events.

  11. The Anatomy of a Continental Tropical Convective Storm.

    NASA Astrophysics Data System (ADS)

    Atlas, David; Williams, Christopher R.

    2003-01-01

    This study provides a very clear picture of the microphysics and flow field in a convective storm in the Rondonia region of Brazil through a synthesis of observations from two unique radars, measurements of the surface drop size distribution (DSD), and particle types and sizes from an aircraft penetration. The primary findings are 1) the growth of rain by the collision-coalescence-breakup (CCB) process to equilibrium drop size distributions entirely below the 0°C level; 2) the subsequent growth of larger ice particles (graupel and hail) at subfreezing temperatures; 3) the paucity of lightning activity during the former process, and the increased lightning frequency during the latter; 4) the occurrence of strong downdrafts and a downburst during the latter phase of the storm resulting from cooling by melting and evaporation; 5) the occurrence of turbulence along the main streamlines of the storm; and 6) the confirmation of the large drops reached during the CCB growth by polarimetric radar observations. These interpretations have been made possible by estimating the updraft magnitude using the `lower bound' of the Doppler spectrum at vertical incidence, and identifying the `balance level' at which particles are supported for growth. The combination of these methods shows where raindrops are supported for extended periods to allow their growth to equilibrium drop size distributions, while smaller drops ascend and large ones descend. A hypothesis worthy of pursuit is the control of the storm motion by the winds at the balance level, which is the effective precipitation generating level. Above the 0°C level the balance level separates the small ascending ice crystals from the large descending graupel and hail. Collisions between the two cause electrical charging, while gravity and the updrafts separate the charges to cause lightning. Below the 0°C level, large downward velocities (caused by the above-mentioned cooling) in excess of the terminal fall speeds of raindrops represent the downbursts, which are manifested in the surface winds.

  12. European climatology of severe convective storm environmental parameters: A test for significant tornado events

    Microsoft Academic Search

    Romualdo Romero; Miquel Gayà; Charles A. Doswell III

    2007-01-01

    A climatology of various parameters associated with severe convective storms has been constructed for Europe. This involves using the reanalysis data base from ERA-40 for the period 1971-2000 and calculating monthly means, variability range and extremes occurrence of fields such as convective available potential energy, convective inhibition energy, mid-tropospheric lapse rate, low-tropospheric moisture content and storm relative helicity for different

  13. Plasmapause Convects to the Magnetopause During Halloween Solar Storm

    NSDL National Science Digital Library

    Tom Bridgman

    2004-12-15

    The plasmasphere is a region of ionospheric plasma which co-rotates with the Earth, carried by the magnetic field lines. The plasmapause marks the outer boundary of this region. This colder plasma is more easily moved by the electric fields created by strong solar storms. In the Halloween 2003 event, these fields convected some of the cold plasma out to the magnetopause (grey, semi-transparent surface) and reduced the size of the cold plasma region near the Earth. For this visualization, the 3-dimensional structure was constructed from the equatorial profile of the plasmapause (as measured by IMAGE-EUV data) by extending the region along field lines of a simple dipole field.

  14. Changes in concentration of Alternaria and Cladosporium spores during summer storms

    NASA Astrophysics Data System (ADS)

    Grinn-Gofro?, Agnieszka; Strzelczak, Agnieszka

    2013-09-01

    Fungal spores are known to cause allergic sensitization. Recent studies reported a strong association between asthma symptoms and thunderstorms that could be explained by an increase in airborne fungal spore concentrations. Just before and during thunderstorms the values of meteorological parameters rapidly change. Therefore, the goal of this study was to create a predictive model for hourly concentrations of atmospheric Alternaria and Cladosporium spores on days with summer storms in Szczecin (Poland) based on meteorological conditions. For this study we have chosen all days of June, July and August (2004-2009) with convective thunderstorms. There were statistically significant relationships between spore concentration and meteorological parameters: positive for air temperature and ozone content while negative for relative humidity. In general, before a thunderstorm, air temperature and ozone concentration increased, which was accompanied by a considerable increase in spore concentration. During and after a storm, relative humidity increased while both air temperature ozone concentration along with spore concentrations decreased. Artificial neural networks (ANN) were used to assess forecasting possibilities. Good performance of ANN models in this study suggest that it is possible to predict spore concentrations from meteorological variables 2 h in advance and, thus, warn people with spore-related asthma symptoms about the increasing abundance of airborne fungi on days with storms.

  15. Remote sensing of severe convective storms over Qinghai-Xizang Plateau

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Liu, J. M.; Tsao, D. Y.; Smith, R. E.

    1984-01-01

    The American satellite, GOES-1 was moved to the Indian Ocean at 58 deg E during the First GARP Global Experiment (FGGE). The Qinghai-Xizang Plateau significantly affects the initiation and development of heavy rainfall and severe storms in China, just as the Rocky Mountains influence the local storms in the United States. Satelite remote sensing of short-lived, meso-scale convective storms is particularly important for covering a huge area of a high elevation with a low population density, such as the Qinghai-Xizang Plateau. Results of this study show that a high growth rate of the convective clouds, followed by a rapid collapse of the cloud top, is associated with heavy rainfall in the area. The tops of the convective clouds developed over the Plateau lie between the altitudes of the two tropopauses, while the tops of convective clouds associated with severe storms in the United States usually extend much above the tropopause.

  16. A study of the relationship between certain moisture parameters and severe convective storms in central Oklahoma

    E-print Network

    Scott, Carven Allen

    1977-01-01

    A STUDY OF THE RELATIONSHIP BETWEEN CERTAIN MOISTURE PARAMETERS AND SEVERE CONVECTIVE STORMS IN CENTRAL OKLAHOMA A Thesis by CARVEN ALLEN SCOTT Submitted to the Graduate College of Texas ASM University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE May 1977 Major Subject: Meteorology A STUDY OF THE RELATIONSHIP BETWEEN CERTAIN MOISTURE PARAMETERS AND SEVERE CONVECTIVE STORMS IN CENTRAL OKLAHOMA A Thesis by CARVEN ALLEN SCOTT Approved as to style...

  17. A Five-Year Climatology of Elevated Severe Convective Storms in the United States East of the Rocky Mountains

    E-print Network

    Schultz, David

    1 A Five-Year Climatology of Elevated Severe Convective Storms in the United States East-year climatology of elevated severe convective storms was constructed for 1983­ 1987 east of the Rocky Mountains days with surface fronts, 129 (8%) were associated with elevated severe-storm cases. Of the 1066 severe

  18. Violent pyro-convective storm devastates Australia's capital and pollutes the stratosphere

    E-print Network

    Daniel, Rosenfeld

    , energetics, and surface manifestations--including suppressed precipitation, an F2 tornado, and black hailViolent pyro-convective storm devastates Australia's capital and pollutes the stratosphere Michael. Citation: Fromm, M., A. Tupper, D. Rosenfeld, R. Servranckx, and R. McRae (2006), Violent pyro-convective

  19. Urban Aerosol Impacts on Downwind Convective Storms SUSAN C. VAN DEN HEEVER AND WILLIAM R. COTTON

    E-print Network

    Collett Jr., Jeffrey L.

    Urban Aerosol Impacts on Downwind Convective Storms SUSAN C. VAN DEN HEEVER AND WILLIAM R. COTTON March 2006, in final form 27 September 2006) ABSTRACT The impacts of urban-enhanced aerosol land use processes and aerosol microphysics are both incorporated. The results indicate that urban

  20. Using CASA IP1 to Diagnose Kinematic and Microphysical Interactions in a Convective Storm

    E-print Network

    Rutledge, Steven

    Using CASA IP1 to Diagnose Kinematic and Microphysical Interactions in a Convective Storm BRENDA the Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project I (IP1) network of polarimetric X levels. IP1 observations of a case on 10 June 2007 show the development of the updraft, subsequent

  1. Transient luminous events above two mesoscale convective systems: Storm structure and evolution

    E-print Network

    Rutledge, Steven

    Click Here for Full Article Transient luminous events above two mesoscale convective systems: Storm with respect to their production of transient luminous events (TLEs), mainly sprites. The 20 June 2007. Meyer, D. R. MacGorman, and S. A. Cummer (2010), Transient luminous events above two mesoscale

  2. Influence of the convection electric field models on predicted plasmapause positions during magnetic storms

    Microsoft Academic Search

    V. Pierrard; G. V. Khazanov; J. Cabrera; J. Lemaire

    2008-01-01

    In the present work, we determine how three well documented models of the magnetospheric electric field, and two different mechanisms proposed for the formation of the plasmapause influence the radial distance, the shape and the evolution of the plasmapause during the geomagnetic storms of 28 October 2001 and of 17 April 2002. The convection electric field models considered are: McIlwain's

  3. Sensitivity of Severe Convective Storms to Soil Moisture and Lower Atmospheric Water Vapor

    NASA Astrophysics Data System (ADS)

    Ancell, Brian; Nauert, Christian

    2014-05-01

    Numerous studies have examined the sensitivity of the atmospheric state to soil moisture on time scales of up to a day. Dry line intensity, lower tropospheric water vapor content, and precipitation have all been shown through modeling studies to be affected by modest perturbations to upstream soil moisture content and subsequent lower atmospheric water vapor. Since all of these aspects could be associated with convection, a high-impact forecast event that exhibits rapid nonlinear error growth, it is reasonable to expect that irrigation practices might influence severe convective storms. Understanding the link between soil moisture and specific convective elements could have broad implications for severe weather forecasting, and could reveal the degree to which irrigation-induced storm-scale inadvertent weather modification exists. This work examines the sensitivity to soil moisture and lower atmospheric water vapor content of a severe convective storm that struck Moore, Oklahoma, USA on May 20th, 2013, killing 24 people. While adjoint sensitivity analysis that employs the tangent linear version of a numerical weather prediction model might be used to examine convective sensitivities to soil moisture, the strong nonlinearity associated with these events likely renders this technique inaccurate. Alternatively, the approach here utilizes backward trajectory analysis to identify the regions up to a day prior to which the storm might be sensitive. Once the regions are identified, an ensemble of model forecasts is created by varying initial soil moisture to reveal the degree to which perturbations must be made to influence the downstream storm. Subsequent comparisons are made between the required soil moisture perturbations and realistic soil water values added through irrigation.

  4. Spatial characteristics of observed precipitation fields: A catalog of summer storms in Arizona, Volume 2

    NASA Technical Reports Server (NTRS)

    Fennessey, N. M.; Eagleson, P. S.; Qinliang, W.; Rodriguez-Iturbe, I.

    1986-01-01

    The parameters of the conceptual model are evaluated from the analysis of eight years of summer rainstorm data from the dense raingage network in the Walnut Gulch catchment near Tucson, Arizona. The occurrence of measurable rain at any one of the 93 gages during a noon to noon day defined a storm. The total rainfall at each of the gages during a storm day constituted the data set for a single storm. The data are interpolated onto a fine grid and analyzed to obtain: an isohyetal plot at 2 mm intervals, the first three moments of point storm depth, the spatial correlation function, the spatial variance function, and the spatial distribution of the total storm depth. The description of the data analysis and the computer programs necessary to read the associated data tapes are presented.

  5. Observations of lightning in convective supercells within tropical storms and hurricanes

    NASA Technical Reports Server (NTRS)

    Lyons, Walter A.; Keen, Cecil S.

    1994-01-01

    Cloud-to-ground (CG) lightning observations from land-based lightning detection networks now allow monitoring this component of the electrical structure of tropical storms and hurricanes within a few hundred kilometers of the United States coastline. Several case studies confirm the long-held opinion that lightning is rather common within the outer rainbands. The general absence of CG lightning within the interior of mature tropical cyclones is also apparent. On the other hand, bursts of CG lightning near the circulation center of developing storms appear to precede periods of further deepening. The CG events are associated with convective supercells, whose anvil canopies can often obscure much of the underlying storm. Near-eyewall CG bursts preceding periods of intensification were noted in Hurricanes Diana (1984) and Florence (1988). A detailed case study of the 1987 unnamed tropical storm that struck the Texas-Louisiana coastline reveals that lightning was associated with two large supercells. These supercells appeared to be the trigger for the development of a closed circulation that formed several hours after the apparent low pressure center made landfall. Further studies of lightning may provide additional insight into the role of convective supercells in tropical storm intensification. It may also provide a useful diagnostic of impending deepening.

  6. Evolution of conserved variables related to storm cells during severe convection in a mesoscale model

    NASA Astrophysics Data System (ADS)

    Weijenborg, Chris; Chagnon, Jeffrey; Friederichs, Petra; Gray, Suzanne; Hense, Andreas

    2014-05-01

    The WEX-MOP project aims at a next generation ensemble prediction system for the mesoscale. One goal of WEX-MOP is to quantify the role of conserved quantities during extreme convective weather. Conserved variables might offer new insight in the predictability of those events. An important conserved quantity is potential vorticity (PV), a fundamental property of the atmospheric flow on synoptic and planetary scales. However, investigations thereof on the atmospheric mesoscale are relatively new. PV has a close relation to rotation and balance, which is important in storm dynamics. Here we characterize the evolution of storm cells in terms of PV to provide new insights into storm dynamics. Tracking of storm cells has been frequently performed using radar and/or satellite data. It received less attention using model data. We present storm cell tracks for two cases of severe convection in June 2011 simulated using the non hydrostatic COSMO-DE weather model. The two cases have a very different background: on 5 June 2011 the convection was primarily locally forced by CAPE, while on 22 June there was strong forcing due to a cold front. For each of the two cases vertical velocity maxima are tracked. High intensity cells in both cases show a high correlation between PV and vertical velocity anomalies. This has been attributed to a strong environment storm relative helicity and/or CAPE close to the surface. For both cases there is a high variability in the cell characteristics. However, the PV anomalies on 22 June are larger than those on 5 June and have a higher correlation between vertical velocity and PV, consistent with the larger wind shear and helicity in the environment at this day. Study of further cases is necessary to test the hypothesis that a high helicity environment leads to more intense long lasting cells.

  7. City of San Diego Water Quality Monitoring Summer Internship The City of San Diego's Transportation and Storm Water Department is looking for

    E-print Network

    Wang, Deli

    The City of San Diego's Transportation and Storm Water Department is looking for summer interns to spend Microbiology lab Please email your resume to: Jessica Erickson Storm Water Environmental Specialist Transportation & Storm Water Department jerickson@sandiego.gov #12;

  8. Saturn's Great Storm of 2010-2011: Cloud particles containing ammonia and water ices indicate a deep convective origin. (Invited)

    NASA Astrophysics Data System (ADS)

    Sromovsky, L. A.; Baines, K. H.; Fry, P.

    2013-12-01

    Saturn's Great Storm of 2010-2011 was first detected by amateur astronomers in early December 2010 and later found in Cassini Imaging Science Subsystem (ISS) images taken on 5 December, when it took the form of a 1000 km wide bright spot. Within a week the head of the storm grew by a factor of ten in width and within a few months created a wake that encircled the planet. This is the sixth Great Saturn Storm in recorded history, all having appeared in the northern hemisphere, and most near northern summer solstice at intervals of roughly 30 years (Sanchez-Lavega et al. 1991, Nature 353, 397-401). That the most recent storm appeared 10 years early proved fortunate because Cassini was still operating in orbit around Saturn and was able to provide unique observations from which we could learn much more about these rare and enormous events. Besides the dramatic dynamical effects displayed at the visible cloud level by high-resolution imaging observations (Sayanagi et al. 2013, Icarus 223, 460-478), dramatic thermal changes also occurred in the stratosphere above the storm (Fletcher et al. 2011, Science 332, 1413), and radio measurements of lightning (Fischer et al., 2011, Nature 475, 75-77) indicated strong convective activity at deeper levels. Numerical models of Saturn's Giant storms (Hueso and Sanchez-Lavega 2004, Icarus 172, 255-271) suggest that they are fueled by water vapor condensation beginning at the 10-12 bar level, some 250 km below the visible cloud tops. That idea is also supported by our detection of water ice near the cloud tops (Sromovsky et al. 2013, Icarus 226, 402-418). From Cassini VIMS spectral imaging taken in February 2011, we learned that the storm's cloud particles are strong absorbers of sunlight at wavelengths from 2.8 to 3.1 microns. Such absorption is not seen on Saturn outside of storm regions, implying a different kind of cloud formation process as well as different cloud composition inside the storm region. We found compelling evidence that the storm cloud contains a multi-component aerosol population. We needed at least three different materials to obtain good spectral fits. The most obvious contributor is ammonia ice, with water ice the best-defined secondary component. The most likely third component is ammonium hydrosulfide or some weakly absorbing material similar to what dominates visible clouds outside the storm region. Horizontally heterogeneous cloud models favor ammonium hydrosulfide as the third component, while horizontally uniform models favor the weak absorber. Both models rely on water ice absorption to compensate for residual spectral gradients produced by ammonia ice from 3.0 microns to 3.1 microns and need the relatively conservative third component to fill in the sharp ammonia ice absorption peak near 2.96 microns. The best heterogeneous model has spatial coverage fractions of 55% ammonia ice, 22% water ice, and 23% ammonium hydrosulfide. The best homogeneous model has an optically thin layer of weakly absorbing particles above an optically thick layer of water ice particles coated by ammonia ice. These Cassini data provide the first spectroscopic evidence of water ice in Saturn's atmosphere. This research was supported by NASA's Outer Planets Research Program under grant NNX11AM58G.

  9. Sensitivity of the Amazon rainforest to convective storms

    NASA Astrophysics Data System (ADS)

    Negron Juarez, R. I.; Chambers, J. Q.; Rifai, S. W.; Urquiza Munoz, J. D.; Tello, R.; Alegria Munoz, W.; Marra, D.; Ribeiro, G.; Higuchi, N.

    2012-12-01

    The Amazon rainforest is the largest contiguous continental tropical forest in the world and is a world center of carbon storage, biodiversity, biogeochemical cycles and biogeophysical processes that affect the Earth climate system. Yet anthropogenic activities have produced changes in the forest-climate system. Consequently, an increase in rainfall in both the Western and Central Amazon and a decrease in the Eastern Amazon are expected due to these anthropogenic activities. While the projected decrease in rainfall has been discussed under the context of drought, deforestation, and fires, the effect of an increase in rainfall, and associated convective processes, on forest ecosystems has been overlooked. Across the Amazon rainforest, Western Amazonia has the highest precipitation rates, wood productivity, soil fertility, recruitment and mortality rates. Yet our field-measured tree mortality data from blowdowns that occurred in Western and Central Amazonia do not show a statistical difference in tree mortality between these regions. However, downburst velocities associated with these disturbances were calculated to be lower in Western Amazonia than in the Central Amazon. This suggests the Western Amazon is more highly sensitive to intense convective systems. This result is particularly relevant given the expected increase in rainfall in the Western and Central Amazon. The increase in rainfall is associated with more intense convective systems that in turn imply an increase in low level jet stream (LLJ) intensity east of the Andes. The presence of the LLJ is the main cause of squall lines and an increase in LLJ intensity will therefore cause increased propagation of squall lines into the Amazon basin. More frequent and active squall lines have the potential to increase the intensity and frequency of downbursts responsible for large forest blowdowns that will affect the biogeophysical feedbacks on the forest ecosystem and carbon budget.

  10. Contribution of the MODIS instrument to observations of deep convective storms and stratospheric moisture detection

    E-print Network

    Wang, Pao K.

    the majority of studies reporting plumes date back to the second half of 80's through the mid- Atmospheric particles within plumes above tops of convective storm anvils (Melani et al., 2003); ­ 3D-modeling of deep to as the "cold-U/V" shape in the 10­12 m IR band imagery and plumes of increased 3.7/3.9 m band reflectivity

  11. Sensitivity of summer ensembles of super-parameterized US mesoscale convective systems to cloud resolving model microphysics and resolution

    NASA Astrophysics Data System (ADS)

    Elliott, E.; Yu, S.; Kooperman, G. J.; Morrison, H.; Wang, M.; Pritchard, M. S.

    2014-12-01

    Microphysical and resolution sensitivities of explicitly resolved convection within mesoscale convective systems (MCSs) in the central United States are well documented in the context of single case studies simulated by cloud resolving models (CRMs) under tight boundary and initial condition constraints. While such an experimental design allows researchers to causatively isolate the effects of CRM microphysical and resolution parameterizations on modeled MCSs, it is still challenging to produce conclusions generalizable to multiple storms. The uncertainty associated with the results of such experiments comes both from the necessary physical constraints imposed by the limited CRM domain as well as the inability to evaluate or control model internal variability. A computationally practical method to minimize these uncertainties is the use of super-parameterized (SP) global climate models (GCMs), in which CRMs are embedded within GCMs to allow their free interaction with one another as orchestrated by large-scale global dynamics. This study uses NCAR's SP Community Atmosphere Model 5 (SP-CAM5) to evaluate microphysical and horizontal resolution sensitivities in summer ensembles of nocturnal MCSs in the central United States. Storm events within each run were identified using an objective empirical orthogonal function (EOF) algorithm, then further calibrated to harmonize individual storm signals and account for the temporal and spatial heterogeneity between them. Three summers of control data from a baseline simulation are used to assess model internal interannual variability to measure its magnitude relative to sensitivities in a number of distinct experimental runs with varying CRM parameters. Results comparing sensitivities of convective intensity to changes in fall speed assumptions about dense rimed species, one- vs. two-moment microphysics, and CRM horizontal resolution will be discussed.

  12. Spatial characteristics of observed precipitation fields: A catalog of summer storms in Arizona, Volume 1

    NASA Technical Reports Server (NTRS)

    Fennessey, N. M.; Eagleson, P. S.; Qinliang, W.; Rodrigues-Iturbe, I.

    1986-01-01

    Eight years of summer raingage observations are analyzed for a dense, 93 gage, network operated by the U. S. Department of Agriculture, Agricultural Research Service, in their 150 sq km Walnut Gulch catchment near Tucson, Arizona. Storms are defined by the total depths collected at each raingage during the noon to noon period for which there was depth recorded at any of the gages. For each of the resulting 428 storms, the 93 gage depths are interpolated onto a dense grid and the resulting random field is anlyzed. Presented are: storm depth isohyets at 2 mm contour intervals, first three moments of point storm depth, spatial correlation function, spatial variance function, and the spatial distribution of total rainstorm depth.

  13. Influence of topography and urban heat island effects on the outbreak of convective storms under unstable meteorological conditions: a numerical study

    Microsoft Academic Search

    J. Thielen; A. Gadian

    1997-01-01

    Analysis of observational data of convective storms in Northern England suggests that the particular combination of effects such as sea breezes, elevated terrain and the presence of large cities has an influence on the initiation and development of convective storms. To study the importance of these effects for the development of convection, a cloud physics model has been initialised with

  14. Lightning, overshooting top and hail characteristics for strong convective storms in Central Europe

    NASA Astrophysics Data System (ADS)

    Jurkovi?, Petra Mikuš; Mahovi?, Nataša Strelec; Po?akal, Damir

    2015-07-01

    Lightning activity in storms with overshooting tops and hail-producing storms over Central Europe is studied, in order to find typical lightning characteristics that can be useful in nowcasting of the severity of the storm and its ability to produce hail. The first part of the study gives the analysis of lightning activity in thunderstorms with overshooting tops (OT) for the warm part of the year (May-September) from 2009 to 2010 over central and southeastern Europe. Deep convective clouds with OT were detected in Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) data, using methods based on the infrared window (IRW, 10.8 ?m) channel and absorption channels of water vapor (WV, 6.2 ?m) and ozone (O3, 9.7 ?m) in the form of brightness temperature differences. The locations and times of the detected OT were compared to the distribution and types of lightning strokes, which were provided by the LINET Lightning Location System. The results show that the spatial distribution of lightning generally coincides with the spatial distribution of the detected OT. The largest numbers of lightning strokes and OT were found in western Hungary, southeastern Austria, northeastern Slovenia and the northern Adriatic. The largest number of OT occurred between 1600 and 1800 UTC, whereas from 0600 to 1000 UTC OT detections were rather rare. Lightning activity showed a similar temporal distribution, with an increase in lightning activity evident at or close to the time of the OT detections. At the time of and close to the location of the OT, the lightning was found to occur well above the tropopause and was clearly related to the OT of cumulonimbus clouds. In the second part of the study, lightning characteristics are studied for 35 events of hail-producing thunderstorms over Croatia in the summer months (May to September), from 2008 to 2012. The lightning distribution, also registered by LINET, was compared to hail parameters based on measurements at the hailpad polygon. A polygon with dimensions of 30 km × 20 km was located in the area of highest average number of days with hail occurrence in the continental part of Croatia. In a majority of the studied cases, the number of total lightning strokes sharply increased slightly before the beginning of hailfall. At the time the hailfall started there is a brief decrease in the number of lightning strokes, followed by a sharp increase shortly after. Additionally, larger hailstones with higher kinetic energy values appeared at the beginning of the hailshower. Microphysical properties of the cloud tops, investigated using MSG SEVIRI 3.9 ?m reflectivity, i.e. profiles of the effective radii of cloud particles vs. temperature, clearly verify the presence of strong updrafts associated with hail-producing clouds.

  15. CONVECTIVE BURSTS AND THE COUPLING OF SATURN'S EQUATORIAL STORMS AND INTERIOR ROTATION

    SciTech Connect

    Heimpel, Moritz [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); Aurnou, Jonathan M., E-mail: mheimpel@ualberta.ca, E-mail: aurnou@ucla.edu [Department of Earth and Space Sciences, University of California, Los Angeles, CA (United States)

    2012-02-10

    Temporal variations of Saturn's equatorial jet and magnetic field hint at rich dynamics coupling the atmosphere and the deep interior. However, it has been assumed that rotation of the interior dynamo must be steady over tens of years of modern observations. Here we use a numerical convection model and scaling estimates to show how equatorial convective bursts can transfer angular momentum to the deeper interior. The numerical model allows angular momentum transfer between a fluid outer spherical shell and a rigid inner sphere. Convection drives a prograde equatorial jet exhibiting quasiperiodic bursts that fill the equatorial volume outside the tangent cylinder. For each burst strong changes in the equatorial surface velocity are associated with retrograde torque on the inner sphere. Our results suggest that Saturn's Great White Spot, a giant storm that was observed to fill the equatorial region in 1990, could mobilize a volume of fluid carrying roughly 15% of Saturn's moment of inertia. Conservation of angular momentum then implies that a 20% change in the equatorial jet angular velocity could change the average interior rotation rate by about 0.1%-roughly an order of magnitude less than the apparent rotation rate changes associated with Saturn's kilometric radio (SKR) signal. However, if the SKR signal originates outside the liquid metal core in a 'planetary tachocline' that separates the layer of fast zonal flow from the magnetically controlled and slowly convecting deep interior, then convective bursts can provide a possible mechanism for the observed {approx}1% SKR changes.

  16. Ionospsheric observation of enhanced convection-initiated gravity waves during tornadic storms

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1981-01-01

    Atmospheric gravity waves associated with tornadoes, with locally severe storms occuring with tornadoes, and with hurricanes were studied through the coupling between the ionosphere and the troposphere. Reverse group ray tracing computations of gravity waves observed by an ionospheric Doppler sounder array were analyzed. The results of ray tracing computations and comparisons between the computed location of the wave sources and with conventional meteorological data indicate that the computed sources of the waves were near the touchdown of the tornadoes, near the eye of the hurricanes, and directly on the squall line of the severe thunderstorms. The signals excited occurred one hour in advance of the tornadoes and three hours in advance of the hurricanes. Satellite photographs show convective overshooting turrets occurring at the same locations and times the gravity waves were being excited. It is suggested that gravity wave observations, conventional meteorological data, and satellite photographs be combined to develop a remote sensing technique for detecting severe storms.

  17. Influence of the Convection Electric Field Models on Predicted Plasmapause Positions During Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Pierrard, V.; Khazanov, G.; Cabrera, J.; Lemaire, J.

    2007-01-01

    In the present work, we determine how three well documented models of the magnetospheric electric field, and two different mechanisms proposed for the formation of the plasmapause influence the radial distance, the shape and the evolution of the plasmapause during the geomagnetic storms of 28 October 2001 and of 17 April 2002. The convection electric field models considered are: Mcllwain's E51) electric field model, Volland-Stern's model and Weimer's statistical model compiled from low-Earth orbit satellite data. The mechanisms for the formation of the plasmapause to be tested are: (i) the MHD theory where the plasmapause should correspond to the last-closed- equipotential (LCE) or last-closed-streamline (LCS), if the E-field distribution is stationary or time-dependent respectively; (ii) the interchange mechanism where the plasmapause corresponds to streamlines tangent to a Zero-Parallel-Force surface where the field-aligned plasma distribution becomes convectively unstable during enhancements of the E-field intensity in the nightside local time sector. The results of the different time dependent simulations are compared with concomitant EUV observations when available. The plasmatails or plumes observed after both selected geomagnetic storms are predicted in all simulations and for all E-field models. However, their shapes are quite different depending on the E-field models and the mechanisms that are used. Despite the partial success of the simulations to reproduce plumes during magnetic storms and substorms, there remains a long way to go before the detailed structures observed in the EUV observations during periods of geomagnetic activity can be accounted for very precisely by the existing E-field models. Furthermore, it cannot be excluded that the mechanisms currently identified to explain the formation of "Carpenter's knee" during substorm events, will', have to be revised or complemented in the cases of geomagnetic storms.

  18. Convective Activities in the Tropical Western Pacific and Their Impact on the Northern Hemisphere Summer Circulation

    Microsoft Academic Search

    Tsuyoshi Nitta

    1987-01-01

    Interannual and intraseasonal variations of convective activities in the tropical western Pacific during summer and their impact on the Northern Hemisphere circulation are investigated by using satellite cloud amount, sea surface temperature (SST) and geopotential data for 7 years (1978-1984). During summers when SST in the tropical western Pacific is about 1.0°C warmer than normal, active convection regions consisting of

  19. Aerosol Indirect Effects on the Cold Pool Characteristics of Convective Storms and Their Subsequent Feedbacks to Convective Development and Surface Precipitation

    NASA Astrophysics Data System (ADS)

    van den Heever, S. C.

    2008-12-01

    Enhanced aerosol concentrations are often associated with a decrease in the surface precipitation through their suppression of the warm rain process. Such changes to the surface precipitation may, however, have an impact on the associated cold pool characteristics, thereby affecting subsequent convective development and the resultant surface precipitation. This dynamic response of the cold pool to enhanced aerosol concentrations may therefore at times offset the aerosol indirect effects on precipitation through its organization of the convection. The relationship between aerosol indirect effects on precipitation characteristics and the associated dynamic forcing of the cold pool has been investigated through the use of several cloud-resolving simulations of convective storms over Florida. Toward the end of NASA's CRYSTAL-FACE field campaign conducted over Florida during July 2002, high concentrations of Saharan dust, which can serve as cloud condensation nuclei and ice nuclei, were observed over the peninsula of Florida. Cloud-resolving model simulations have been conducted using the Regional Atmospheric Modeling System (RAMS) to investigate the impacts of varying aerosol concentrations on the characteristics of the convection developing over the Peninsula. The model was initialized with vertical profiles of both clean and high aerosol concentrations observed during the field campaign. Results from the simulations show that while enhanced aerosol concentrations do tend to result in a decrease in the surface precipitation throughout much of the lifecycle of the storms, there are however times when the precipitation produced by the high aerosol case is greater than that of the clean case. It is during these times that the gust fronts of the storms in the clean case have outrun their associated updrafts, resulting in a weakening of the storm system and a concomitant decrease in surface precipitation. In the high aerosol case the updrafts remain co-located with their gust fronts producing a relatively steady storm system and greater surface precipitation rates than in the clean case, until such time as the storm systems re-develop in the clean case. The details of the aerosol indirect effects on the microphysical and precipitation characteristics of these convective storms, their resultant impacts on the cold pool characteristics and dynamical forcing of convection, and the subsequent influence on surface precipitation will be presented.

  20. A two year (2008-2009) analysis of severe convective storms in the Mediterranean basin as observed by satellite imagery

    Microsoft Academic Search

    B. Gozzini; S. Melani; F. Pasi; A. Ortolani

    2010-01-01

    The increasing damages caused by natural disasters, a great part of them being direct or indirect effects of severe convective storms (SCS), seem to suggest that extreme events occur with greater frequency, also as a consequence of climate changes. A better comprehension of the genesis and evolution of SCS is then necessary to clarify if and what is changing in

  1. Climatology and variability of the Middle Eastern summer Shamal wind : Implications to dust storm variability

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Notaro, M.

    2014-12-01

    The climatology and variability of Shamal wind, an important regulator of summertime Middle Eastern dust storm activity, have been poorly characterized in the scientific literature. The Middle Eastern Shamal is a strong low-level northwesterly wind, which can lift dust from the Syrian and Iraqi deserts and transport it to the Persian Gulf and Arabian Peninsula. Despite its critical role as a dust storm driver, the variability and controls of summertime Shamal wind has not been addressed by previous studies. The spatial distribution and seasonal cycle of the Shamal wind during 1970-2013, along with its interannual variability, covariability with dust storm activities, and potential link to sea surface temperatures (SSTs) in the tropical Pacific Ocean and Mediterranean Sea, are studied using hourly station records, reanalysis data, and remotely-sensed data. According to a wind-direction and speed-based criterion for Shamal days, the summertime Shamal behaves like a summer monsoon with variability in its onset, termination, and distinct break periods. Based on a multi-station criterion for Shamal onset and termination, the onset occurs on May 23 ± 8 days (one standard deviation), and the termination date is Sep 2 ± 21 days. The highest wind speed on a Shamal day occurs around the noon along the west coast of the Persian Gulf, corresponding to a peak in horizontal pressure gradient. The onset of Shamal is associated with the development of low pressure over Iran and high pressure over the eastern Mediterranean and northwestern Arabian Peninsula - an eastward expansion of the high over subtropical Atlantic. El Niño events support the delayed onset and weaker intensity of the summer Shamal. Intensified summer Shamal winds are associated with anomalously cool Mediterranean SSTs, which enhance the high pressure over the eastern Mediterranean. The impacts of El Niño-Southern Oscillation and Mediterranean SSTs on summer Shamal are validated by an independent statistical method, the General Equilibrium Feedback Assessment. Periods of enhanced Shamal wind intensity favor increased summertime floating dust frequency (temporal correlation = 0.77,1975-2013), dust storm frequency (temporal correlation = 0.57, 1975-2013), and aerosol optical depth (temporal correlation = 0.73, 2000-2013).

  2. P1.22 A FIVE-YEAR CLIMATOLOGY OF ELEVATED SEVERE CONVECTIVE STORMS IN THE UNITED STATES EAST OF THE ROCKY MOUNTAINS

    E-print Network

    Schultz, David

    P1.22 A FIVE-YEAR CLIMATOLOGY OF ELEVATED SEVERE CONVECTIVE STORMS IN THE UNITED STATES EAST be either surface based or elevated. Surface-based deep convection ingests parcels of air from near the surface, whereas elevated convection ingests parcels of air from above a frontal surface or surface

  3. The impact of vegetation on the atmospheric boundary layer and convective storms

    SciTech Connect

    Lee, T.J.

    1992-01-01

    The impact of vegetation on atmospheric boundary layer and convective storms is examined through the construction and testing of a soil-vegetation-atmospheric transfer (SVAT) model. The Land Ecosystem-Atmospheric (LEAF) model is developed using an elevated canopy structure, an above-canopy aerodynamic resistance, two in-canopy aerodynamic resistances, and one stomatal conductance functions. The air temperature and humidity are assumed to be constant in the canopy whereas the wind and radiation follow a specified vertical profile. A simple dump-bucket method is used to parameterize the interception of precipitation and a multi-layer soil model is utilized to handle the vertical transfer of soil water. Evaporation from soil and wet leaves and transpiration from dry leaves are evaluated separately. The solid water uptake is based on soil water potential rather than on length of roots. Separate energy budgets for vegetation and for soil are used in order to remove unnecessary assumptions on energy partition between the vegetation and the substrate. Primary parameters are LAI, maximum stomatal conductance, and albedo. Secondary parameters include displacement height and environmental controls on stomatal resistance function. The Multi-response Randomized Bock Permutation (MRBP) procedure is used to help choose the model parameter values. The Fourier Amplitude Sensitivity Test (FAST) is applied to understand the model behavior in response to changes in model parameters. LEAF is used to study growth of boundary layer and local thermal circulations generated by surface inhomogeneities. Results show that atmospheric boundary layer is cooler and more moist over unstressed vegetation than over bare dry soil. Thermally forced circulation can result from the juxtaposition of two vegetation types due to different biophysical characteristics. Simulations show that the surface spatial heterogeneities made by vegetation play an important role in generating local convective storms.

  4. Severe convection and lightning in subtropical South America

    NASA Astrophysics Data System (ADS)

    Rasmussen, Kristen L.; Zuluaga, Manuel D.; Houze, Robert A.

    2014-10-01

    Satellite radar and radiometer data show that subtropical South America has the world's deepest convective storms, robust mesoscale convective systems, and very frequent large hail. We determine severe weather characteristics for the most intense precipitation features seen by satellite in this region. In summer, hail and lightning concentrate over the foothills of western Argentina. Lightning has a nocturnal maximum associated with storms having deep and mesoscale convective echoes. In spring, lightning is maximum to the east in association with storms having mesoscale structure. A tornado alley is over the Pampas, in central Argentina, distant from the maximum hail occurrence, in association with extreme storms. In summer, flash floods occur over the Andes foothills associated with storms having deep convective cores. In spring, slow-rise floods occur over the plains with storms of mesoscale dimension. This characterization of high-impact weather in South America provides crucial information for socioeconomic implications and public safety.

  5. Sensitivity analysis of numerically-simulated convective storms using direct and adjoint methods

    SciTech Connect

    Park, S.K.; Droegemeier, K.K. [Univ. of Oklahoma, Norman, OK (United States); Bischof, C.; Knauff, T. [Argonne National Lab., IL (United States). Mathematics and Computer Science Div.

    1994-06-01

    The goal of this project is to evaluate the sensitivity of numerically modeled convective storms to control parameters such as the initial conditions, boundary conditions, environment, and various physical and computational parameters. In other words, the authors seek the gradient of the solution vector with respect to specified parameters. One can use two approaches to accomplish this task. In the first or so-called brute force method, one uses a fully nonlinear model to generate a control forecast starting from a specified initial state. Then, a number of other forecasts are made in which chosen parameters (e.g., initial conditions) are systematically varied. The obvious drawback is that a large number of full model predictions are needed to examine the effects of only a single parameter. The authors describe herein an alternative, essentially automated method (ADIFOR, or Automatic DIfferentiation of FORtran) for obtaining the solution gradient that bypasses the adjoint altogether yet provides even more information about the gradient. (ADIFOR, like the adjoint technique, is constrained by the linearity assumption.) Applied to a 1-D moist cloud model, the authors assess the utility of ADIFOR relative to the brute force approach and evaluate the validity of the tangent linear approximation in the context of deep convection.

  6. Fluid dynamic simulation of severe convective storms, initiation of convection due to gravity waves and their comparison with rapid-scan infrared sensing from geosynchronous satellite

    NASA Astrophysics Data System (ADS)

    Tsao, Yow-Min David

    Both rawinsonde data and geosynchronous satellite imagery were used to study the life cycle of severe convective clouds. Cloud modelling with input sounding data from the nearest rawinsonde data and rapid-scan imagery from GOES were used to investigate storm cloud formation development and dissipation in terms of growth and collapse of cloud tops, as well as the life cycle of the penetration of overshooting turrets above the tropopause. The results showed that storm clouds developed to a mature stage with overshooting cloud tops penetrating above the tropopause and collapsed several minutes before the touchdown of tornadoes. At the time of storm dissipation, cloud tops dissipated with a high rate several minutes before the lift-off time of tornadoes. Cloud modelling also shows that the local tropopause height decreased during the period of overshooting cloud tops penetrating above the tropopause.

  7. Evaluation and development of satellite inferences of convective storm intensity using combined case study analysis and thunderstorm model simulations

    NASA Technical Reports Server (NTRS)

    Cotton, W. R.; Tripoli, G. J.

    1980-01-01

    Major research accomplishments which were achieved during the first year of the grant are summarized. The research concentrated in the following areas: (1) an examination of observational requirements for predicting convective storm development and intensity as suggested by recent numerical experiments; (2) interpretation of recent 3D numerical experiments with regard to the relationship between overshooting tops and surface wind gusts; (3) the development of software for emulating satellite-inferred cloud properties using 3D cloud model predicted data; and (4) the development of a conceptual/semi-quantitative model of eastward propagating, mesoscale convective complexes forming to the lee of the Rocky Mountains.

  8. Using a WRF simulation to examine regions where convection impacts the Asian summer monsoon anticyclone

    NASA Astrophysics Data System (ADS)

    Heath, Nicholas Kyle

    The Asian summer monsoon is a dominant feature of the global circulation. The upper-level anticyclone (ULAC) associated with the Asian summer monsoon circulation stands out vividly in satellite observations of trace gases. The ULAC also has been diagnosed as a region that is important to troposphere-to-stratosphere transport. Therefore, understanding the role of convection in transporting boundary layer air into this upper-level circulation is important to understanding the atmospheric chemistry of the upper troposphere/lower stratosphere. We ran the Weather Research and Forecasting (WRF) model at convective-permitting scales (4 km grid spacing) to simulate the atmosphere between 10--20 August 2012. Such high-resolution modeling of the Asian ULAC previously has not been documented in the literature. Comparison of our WRF simulation with reanalysis and satellite observations showed that WRF simulated the atmosphere sufficiently well to be used to study convective transport into the ULAC. A back-trajectory analysis showed that >90% of convectively influenced parcels reaching the ULAC came from the Tibetan Plateau (TP) and the southern slope (SS) of the Himalayas. A clear diurnal cycle is seen in the convective parcels, with their greatest impact occurring between 1600--2300 local solar time. This finding highlights the role of "everyday" diurnal convection in transporting boundary layer air into the ULAC. WRF output at 15 min intervals was produced for 16 August to examine convection in greater detail. This high-temporal output indicated that the weakest convection occurred over the TP. However, because the TP is at 3000--5000 m MSL, its convection does not have to be as strong to reach the ULAC as in lower altitude regions. Additionally, because the TP's elevated heat source is a major cause of the ULAC, we propose that convection over the TP and the neighboring SS is geographically situated to impact the ULAC most frequently. The vertical mass flux of water vapor into the ULAC also was calculated. Results show that the TP and SS regions dominated other Asian regions in vertically transporting moisture into the ULAC. Because convection reaching the ULAC is more widespread over the TP than nearby, we propose that the abundant convection partially explains the TP's dominant water vapor fluxes. In addition, greater outgoing longwave radiation reaches the upper levels of the TP due to its elevated terrain. This creates a warmer ambient upper level environment, allowing parcels with greater saturation mixing ratios to enter the ULAC.

  9. Using a WRF simulation to examine regions where convection impacts the Asian summer monsoon anticyclone

    NASA Astrophysics Data System (ADS)

    Heath, N. K.; Fuelberg, H. E.

    2013-09-01

    The Asian summer monsoon is a prominent feature of the global circulation that is associated with an upper-level anticyclone (ULAC) that stands out vividly in satellite observations of trace gases. The ULAC also is an important region of troposphere-to-stratosphere transport. We ran the Weather Research and Forecasting (WRF) model at convective-permitting scales (4 km grid spacing) between 10-20 August 2012 to understand the role of convection in transporting boundary layer air into the upper-level anticyclone. Such high-resolution modeling of the Asian ULAC previously has not been documented in the literature. Comparison of our WRF simulation with reanalysis and satellite observations showed that WRF simulated the atmosphere sufficiently well to be used to study convective transport into the ULAC. A back-trajectory analysis based on hourly WRF output showed that > 90% of convectively influenced parcels reaching the ULAC came from the Tibetan Plateau (TP) and the southern slope (SS) of the Himalayas. A distinct diurnal cycle is seen in the convective trajectories, with their greatest impact occurring between 1600-2300 local solar time. This finding highlights the role of "everyday" diurnal convection in transporting boundary layer air into the ULAC. WRF output at 15 min intervals was produced for 16 August to examine the convection in greater detail. This high-temporal output revealed that the weakest convection in the study area occurred over the TP. However, because the TP is at 3000-5000 m a.m.s.l., its convection does not have to be as strong to reach the ULAC as in lower altitude regions. In addition, because the TP's elevated heat source is a major cause of the ULAC, we propose that convection over the TP and the neighboring SS is ideally situated geographically to impact the ULAC. The vertical mass flux of water vapor into the ULAC also was calculated. Results show that the TP and SS regions dominate other Asian regions in transporting moisture vertically into the ULAC. Because convection reaching the ULAC is more widespread over the TP than nearby, we propose that the abundant convection partially explains the TP's dominant water vapor fluxes. In addition, greater outgoing longwave radiation reaches the upper levels of the TP due to its elevated terrain. This creates a warmer ambient upper level environment, allowing parcels with greater saturation mixing ratios to enter the ULAC. Lakes in the Tibetan Plateau are shown to provide favorable conditions for deep convection during the night.

  10. Using a WRF simulation to examine regions where convection impacts the Asian summer monsoon anticyclone

    NASA Astrophysics Data System (ADS)

    Heath, N. K.; Fuelberg, H. E.

    2014-02-01

    The Asian summer monsoon is a prominent feature of the global circulation that is associated with an upper-level anticyclone (ULAC) that stands out vividly in satellite observations of trace gases. The ULAC also is an important region of troposphere-to-stratosphere transport. We ran the Weather Research and Forecasting (WRF) model at convective-permitting scales (4 km grid spacing) between 10 and 20 August 2012 to understand the role of convection in rapidly transporting boundary layer air into the ULAC. Such high-resolution modeling of the Asian ULAC previously has not been documented in the literature. Comparison of our WRF simulation with reanalysis and satellite observations showed that WRF simulated the atmosphere sufficiently well to be used to study convective transport into the ULAC. A back-trajectory analysis based on hourly WRF output showed that > 90% of convectively influenced parcels reaching the ULAC came from the Tibetan Plateau (TP) and the southern slope (SS) of the Himalayas. A distinct diurnal cycle is seen in the convective trajectories, with a majority of them crossing the boundary layer between 1600 and 2300 local solar time. This finding highlights the role of "everyday" diurnal convection in transporting boundary layer air into the ULAC. WRF output at 15 min intervals was produced for 16 August to examine the convection in greater detail. This high-temporal output revealed that the weakest convection in the study area occurred over the TP. However, because the TP is at 3000-5000 m a.m.s.l., its convection does not have to be as strong to reach the ULAC as in lower altitude regions. In addition, because the TP's elevated heat source is a major cause of the ULAC, we propose that convection over the TP and the neighboring SS is ideally situated geographically to impact the ULAC. The vertical mass flux of water vapor into the ULAC also was calculated. Results show that the TP and SS regions dominate other Asian regions in transporting moisture vertically into the ULAC. Because convection reaching the ULAC is more widespread over the TP than nearby, we propose that the abundant convection partially explains the TP's dominant water vapor fluxes. In addition, greater outgoing longwave radiation reaches the upper levels of the TP due to its elevated terrain. This creates a warmer ambient upper-level environment, allowing parcels with greater saturation mixing ratios to enter the ULAC. Lakes in the Tibetan Plateau are shown to provide favorable conditions for deep convection during the night.

  11. Using a WRF simulation to examine regions where convection impacts the Asian summer monsoon anticyclone

    NASA Astrophysics Data System (ADS)

    Heath, N.; Fuelberg, H. E.

    2013-12-01

    The Asian summer monsoon is a prominent feature of the global circulation that is associated with an upper-level anticyclone (ULAC) that stands out vividly in satellite observations of trace gases. The ULAC also is an important region of troposphere-to-stratosphere transport. We ran the Weather Research and Forecasting (WRF) model at convective-permitting scales (4 km grid spacing) between 10-20 August 2012 to understand the role of convection in transporting boundary layer air into the upper-level anticyclone. Such high-resolution modeling of the Asian ULAC previously has not been documented in the literature. Comparison of our WRF simulation with reanalysis and satellite observations showed that WRF simulated the atmosphere sufficiently well to be used to study convective transport into the ULAC. A back-trajectory analysis based on hourly WRF output showed that >90% of convectively influenced parcels reaching the ULAC came from the Tibetan Plateau (TP) and the southern slope (SS) of the Himalayas. A distinct diurnal cycle is seen in the convective trajectories, with their greatest impact occurring between 1600-2300 local solar time. This finding highlights the role of 'everyday' diurnal convection in transporting boundary layer air into the ULAC. WRF output at 15 min intervals was produced for 16 August to examine the convection in greater detail. This high-temporal output revealed that the weakest convection in the study area occurred over the TP. However, because the TP is at 3000-5000 m MSL, its convection does not have to be as strong to reach the ULAC as in lower altitude regions. In addition, because the TP's elevated heat source is a major cause of the ULAC, we propose that convection over the TP and the neighboring SS is ideally geographically situated to impact the ULAC. The vertical mass flux of water vapor into the ULAC also was calculated. Results show that the TP and SS regions dominate other Asian regions in vertically transporting moisture into the ULAC. Because convection reaching the ULAC is more widespread over the TP than nearby, we propose that the abundant convection partially explains the TP's dominant water vapor fluxes. In addition, greater outgoing longwave radiation reaches the upper levels of the TP due to its elevated terrain. This creates a warmer ambient upper level environment, allowing parcels with greater saturation mixing ratios to enter the ULAC. Lakes in the Tibetan Plateau are shown to provide favorable conditions for deep convection during the night.

  12. Urban Effects on Summer Monsoon Convection in Phoenix, Arizona (USA): A Model Case Study of Aug. 2-3, 2005

    E-print Network

    Castro, Christopher L.

    Urban Effects on Summer Monsoon Convection in Phoenix, Arizona (USA): A Model Case Study of Aug. 2 sensitivity analysis, the impact of urban physical characteristics that may affect thunderstorm development of the convective event reasonably well. In agreement with the observed precipitation pattern, urban physical

  13. Convective and stratiform rainfall and heating associated with the summer monsoon over the South China Sea based on TRMM data

    Microsoft Academic Search

    W. Li; D. Wang; T. Lei; H. Wang

    2009-01-01

    Summary  In this study, we investigate the features of the convective and stratiform rainfall and latent heating associated with the\\u000a summer monsoon over the South China Sea using TRMM data. Our findings are as follows. (1) Latent heating generated by the\\u000a convective and stratiform heating algorithm (CSH), as well as convective and stratiform rainfall from satellite data can characterize\\u000a the seasonal

  14. Can stable isotopes ride out the storms? The role of convection for water isotopes in models, records, and paleoaltimetry studies in the central Andes

    NASA Astrophysics Data System (ADS)

    Rohrmann, Alexander; Strecker, Manfred R.; Bookhagen, Bodo; Mulch, Andreas; Sachse, Dirk; Pingel, Heiko; Alonso, Ricardo N.; Schilgen, Taylor F.; Montero, Carolina

    2015-04-01

    Globally, changes in stable isotope ratios of oxygen and hydrogen (?18O and ?D) in the meteoric water cycle result from distillation and evaporation processes. Isotope fractionation occurs when air masses rise in elevation, cool, and reduce their water-vapor holding capacity with decreasing temperature. As such, d18O and dD values from a variety of sedimentary archives are often used to reconstruct changes in continental paleohydrology as well as paleoaltimetry of mountain ranges. Based on 234 stream-water samples, we demonstrate that areas experiencing deep convective storms in the eastern south-central Andes (22 - 28° S) do not show the commonly observed relationship between ?18O and ?D with elevation. These convective storms arise from intermontane basins, where diurnal heating forces warm air masses upward, resulting in cloudbursts and raindrop evaporation. Especially at the boundary between the tropical and extra-tropical atmospheric circulation regimes where deep-convective storms are very common (~ 26° to 32° N and S), the impact of such storms may yield non-systematic stable isotope-elevation relationships as convection dominates over adiabatic lifting of air masses. Because convective storms can reduce or mask the depletion of heavy isotopes in precipitation as a function of elevation, linking modern or past topography to patterns of stable isotope proxy records can be compromised in mountainous regions, and atmospheric circulation models attempting to predict stable isotope patterns must have sufficiently high spatial resolution to capture the fractionation dynamics of convective cells. Rohrmann, A. et al. Can stable isotopes ride out the storms? The role of convection for water isotopes in models, records, and paleoaltimetry studies in the central Andes. Earth Planet. Sci. Lett. 407, 187-195 (2014).

  15. The vertical profile of radar reflectivity of convective cells: A strong indicator of storm intensity and lightning probability?

    NASA Technical Reports Server (NTRS)

    Zipser, Edward J.; Lutz, Kurt R.

    1994-01-01

    Reflectivity data from Doppler radars are used to construct vertical profiles of radar reflectivity (VPRR) of convective cells in mesoscale convective systems (MCSs) in three different environmental regimes. The National Center for Atmospheric Research CP-3 and CP-4 radars are used to calculate median VPRR for MCSs in the Oklahoma-Kansas Preliminary Regional Experiment for STORM-Central in 1985. The National Oceanic and Atmospheric Administration-Tropical Ocean Global Atmosphere radar in Darwin, Australia, is used to calculate VPRR for MCSs observed both in oceanic, monsoon regimes and in continental, break period regimes during the wet seasons of 1987/88 and 1988/89. The midlatitude and tropical continental VPRRs both exhibit maximum reflectivity somewhat above the surface and have a gradual decrease in reflectivity with height above the freezing level. In sharp contrast, the tropical oceanic profile has a maximum reflectivity at the lowest level and a very rapid decrease in reflectivity with height beginning just above the freezing level. The tropical oceanic profile in the Darwin area is almost the same shape as that for two other tropical oceanic regimes, leading to the conclustion that it is characteristic. The absolute values of reflectivity in the 0 to 20 C range are compared with values in the literature thought to represent a threshold for rapid storm electrification leading to lightning, about 40 dBZ at -10 C. The large negative vertical gradient of reflectivity in this temperature range for oceanic storms is hypothesized to be a direct result of the characteristically weaker vertical velocities observed in MCSs over tropical oceans. It is proposed, as a necessary condition for rapid electrification, that a convective cell must have its updraft speed exceed some threshold value. Based upon field program data, a tentative estimate for the magnitude of this threshold is 6-7 m/s for mean speed and 10-12 m/s for peak speed.

  16. Observations on thermospheric and mesospheric density disturbances caused by typhoons and convective storms

    Microsoft Academic Search

    R. J. Hung; Y. D. Tsao; C. C. Lee; D. L. Johnson; A. J. Chen

    1990-01-01

    Atmospheric parameter observations have been conducted during the passage of typhoons and tropical storms, from the troposphere to the middle atmosphere, and thence to the thermosphere, using the VHF radar and HF Doppler sounder at an observation site in Taiwan. The density perturbations caused by the propagation of gravity waves due to the typhoons and tropical storms were calculated on

  17. Arctic Storms and Their Links to Surface Energy Budget Changes at the Onset and End of the Summer Melt Season Over Pack Ice

    Microsoft Academic Search

    O. P. Persson; A. Solomon; M. Shupe; A. J. Gasiewski

    2008-01-01

    The length of the Arctic melt season has been observed to be increasing over the last two decades. However, the processes which initiate and end the summer melt season have not been studied in detail. Point observations at the Surface Heat Budget of the Arctic Ocean (SHEBA) site during the summer of 1998 suggest that Arctic storms over the pack

  18. Mesoscale model simulations of TRACE A and Preliminary Regional Experiment for Storm-scale Operational and Research Meteorology convective systems and associated tracer transport

    Microsoft Academic Search

    Y. Wang; W.-K. Tao; K. E. Pickering; A. M. Thompson; J. S. Kain; R. F. Adler; J. Simpson; P. R. Keehn; G. S. Lai

    1996-01-01

    A tropical mesoscale convective system (MCS) during the Transport and Atmospheric Chemistry Near the Equator-Atlantic (TRACE A) experiment and a midlatitude squall line during Preliminary Regional Experiment for Storm-scale Operational and Research Meteorology (PRESTORM) were simulated with the National Center for Atmospheric Research\\/Pennsylvania State University (NCAR\\/PSU) MM5 model. For the TRACE A case the model simulation predicted locations of convection

  19. Heat transfers in a double-skin roof ventilated by natural convection in summer time

    E-print Network

    Biwole, Pascal; Pompeo, C

    2013-01-01

    The double-skin roofs investigated in this paper are formed by adding a metallic screen on an existing sheet metal roof. The system enhances passive cooling of dwellings and can help diminishing power costs for air conditioning in summer or in tropical and arid countries. In this work, radiation, convection and conduction heat transfers are investigated. Depending on its surface properties, the screen reflects a large amount of oncoming solar radiation. Natural convection in the channel underneath drives off the residual heat. The bi-dimensional numerical simulation of the heat transfers through the double skin reveals the most important parameters for the system's efficiency. They are, by order of importance, the sheet metal surface emissivity, the screen internal and external surface emissivity, the insulation thickness and the inclination angle for a channel width over 6 cm. The influence of those parameters on Rayleigh and Nusselt numbers is also investigated. Temperature and air velocity profiles on seve...

  20. On the statistical relationship between cloud optical and microphysical characteristics and rainfall intensity for convective storms over the Mediterranean

    NASA Astrophysics Data System (ADS)

    Cattani, E.; Torricella, F.; Laviola, S.; Levizzani, V.

    2009-12-01

    The relationship between the multi-spectral cloud field characterization from the Advanced Very High Resolution Radiometer (AVHRR) and the rainfall intensities from the Advanced Microwave Sounding Unit-module B (AMSU-B) data were studied for a convective storm event, which occurred during the first 15 days of June 2007 over the Mediterranean. The cloud products exploited in this analysis, cloud mask, type, optical thickness, and effective radius, are obtained from the NOAA-NESDIS operational processing system Clouds from the AVHRR-Extended algorithm (CLAVR-x), whereas the rain intensity values are retrieved from the AMSU-B brightness temperatures via a fast algorithm, using opaque frequencies (centred at 183 GHz) to correct for the presence of water vapour affecting the retrieval results. The algorithm is conceived to discriminate between convective and stratiform rain using a suitable set of thresholds; the retrieval is subsequently carried out separately for the two types. A test for the discrimination of precipitating from non-precipitating areas was based on the comparison between the precipitation information and the retrieved cloud parameters. The test produced a cloud optical thickness threshold value, beyond which the precipitation initiates, and an effective radius range for the identification of the precipitating clouds. The results stemming from the application of the test to the June 2007 case study are very encouraging, although still preliminary and restricted to the analyzed Mediterranean storms. In particular, the test shows high potential for delineating non-precipitating areas (more than 90% of successful cases for every considered cloud type) and to identify precipitating ice clouds related to convective rain (confirmed by 82% of hits). On the other hand, the relative inability to address the stratiform cloud systems is proved by the fact that the majority of the missed cases, for each cloud types, is characterized by light rain intensities (?3 mm h-1).

  1. Observations on thermospheric and mesospheric density disturbances caused by typhoons and convective storms

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Tsao, Y. D.; Lee, C. C.; Johnson, D. L.; Chen, A. J.

    1990-01-01

    Atmospheric parameter observations have been conducted during the passage of typhoons and tropical storms, from the troposphere to the middle atmosphere, and thence to the thermosphere, using the VHF radar and HF Doppler sounder at an observation site in Taiwan. The density perturbations caused by the propagation of gravity waves due to the typhoons and tropical storms were calculated on the basis of these observations. The short-term middle atmospheric and thermospheric density changes are significant factors in spacecraft launches. The successful remote measurement of three-dimensional winds, gravity waves, and density perturbations is demonstrated for this subtropical site.

  2. Origin of the pre-tropical storm Debby (2006) African easterly wave-mesoscale convective system

    NASA Astrophysics Data System (ADS)

    Lin, Yuh-Lang; Liu, Liping; Tang, Guoqing; Spinks, James; Jones, Wilson

    2013-05-01

    The origins of the pre-Debby (2006) mesoscale convective system (MCS) and African easterly wave (AEW) and their precursors were traced back to the southwest Arabian Peninsula, Asir Mountains (AS), and Ethiopian Highlands (EH) in the vicinity of the ITCZ using satellite imagery, GFS analysis data and ARW model. The sources of the convective cloud clusters and vorticity perturbations were attributed to the cyclonic convergence of northeasterly Shamal wind and the Somali jet, especially when the Mediterranean High shifted toward east and the Indian Ocean high strengthened and its associated Somali jet penetrated farther to the north. The cyclonic vorticity perturbations were strengthened by the vorticity stretching associated with convective cloud clusters in the genesis region—southwest Arabian Peninsula. A conceptual model was proposed to explain the genesis of convective cloud clusters and cyclonic vorticity perturbations preceding the pre-Debby (2006) AEW-MCS system.

  3. The impact of climate change on severe convective storms over Europe

    Microsoft Academic Search

    J. Sander; N. Dotzek

    2010-01-01

    The impact of climate change on severe convection over Europe is assessed by deriving convection-indices on the basis of 3-dimensional meteorological fields of two simulations of the regional climate model CLM: one simulation for the past (1979-2000) and one for the future (2079-2100). Verification of the method is attained by comparing the results with sounding-derived parameters on the basis of

  4. Revisiting the latent heat nudging scheme for the rainfall assimilation of a simulated convective storm

    Microsoft Academic Search

    D. Leuenberger; A. Rossa

    2007-01-01

    Summary  Next-generation, operational, high-resolution numerical weather prediction models require economical assimilation schemes\\u000a for radar data. In the present study we evaluate and characterise the latent heat nudging (LHN) rainfall assimilation scheme\\u000a within a meso-? scale NWP model in the framework of identical twin simulations of an idealised supercell storm. Consideration\\u000a is given to the model’s dynamical response to the forcing as

  5. Modeling Ionospheric Convection During a Major Geomagnetic Storm on October 22-23, 1981

    NASA Technical Reports Server (NTRS)

    Moses, J. J.; Slavin, J. A.; Aggson, T. L.; Heelis, R. A.; Winningham, J. D.

    1994-01-01

    Following the passage of an interplanetary shock at approximately 0500 UT, a major geomagnetic storm developed on October 22-23, 1981. Numerous auroral substorms occurred during this storm leading to an AE index greater than 1000 nT. We have used the expanding/contracting polar cap (ECPC) model (Moses et al., 1989) and data from the Dynamics Explorer 2 spacecraft to study the ionospheric electric fields for 12 consecutive traversals of the polar regions. The ECPC model can determine the voltage drops across the dayside merging and nightside reconnection gaps. We determined the relationship of the AL index (i.e., the intensity of the westward electrojet) to the nightside reconnection potential drop. An excellent linear correlation was found between the nightside reconnection gap voltage drop and the AL index. These results show that the solar wind strongly drives the magnetosphere-ionosphere system throughout the geomagnetic storm. A substantial level of dayside merging seems to occur throughout the event. Nightside reconnection varies from satellite pass to satellite pass and within the substorm recovery phase. We find that tail reconnection is an important feature of the recovery phase of substorms.

  6. Convective storms over Germany during Pentecost 2014: Numerical sensitivity studies with the COSMO model

    NASA Astrophysics Data System (ADS)

    Barthlott, Christian; Mühr, Bernhard; Hoose, Corinna

    2015-04-01

    During Pentecost 2014, central Europe was affected by an unusually high number of convective systems leading to severe damages due to strong winds, heavy precipitation, hail, and lightning. In Germany, wind gusts of 144 km/h were observed at Duesseldorf airport and maximum temperatures reached nearly 38 degrees C in southwestern Germany. An almost stationary low pressure system over the northern Atlantic and a ridge stretching from Africa to northern Europe led to very high low-level temperatures due to advection of warm air in combination with solar insolation. We present convection-permitting numerical simulations for two days of this event (8 and 9 June 2014) using the COnsortium for Small-scale MOdeling (COSMO) model. Whereas a reference run with more or less operational settings was successful in reproducing the convective events of the first day, it failed to adequately reproduce the events of the second day. Several sensitivity studies with an enlarged model domain, increased horizontal grid spacing, and using a more sophisticated 2-moment microphysical scheme are conducted to investigate the reasons for model deficiencies and convection initiation in general.

  7. Midweek increase in U.S. summer rain and storm heights suggests air pollution invigorates rainstorms

    Microsoft Academic Search

    Thomas L. Bell; Daniel Rosenfeld; Kyu-Myong Kim; Jung-Moon Yoo; Myong-In Lee; Maura Hahnenberger

    2008-01-01

    Tropical Rainfall Measuring Mission (TRMM) satellite estimates of summertime rainfall over the southeast U.S. are found on average to be significantly higher during the middle of the work week than on weekends, attributable to a midweek intensification of afternoon storms and an increase in area with detectable rain. TRMM radar data show a significant midweek increase in the echo-top heights

  8. Mesospheric concentric gravity waves generated by multiple convection storms over the North America Great Plain

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Yue, J.; Vadas, S. L.

    2011-12-01

    A six-hour continuous airglow imager observation of convectively generated gravity waves (GW) in the mesopause region near Fort Collins, Colorado, on 08 September 2005 is reported. These GWs show nearly concentric ring or arc patterns, centered on top of the locations of numerous updraft within multiple thunderstorm systems, as well as the places where hails were collected concurrently. The existence of the GWs in the airglow layer (~87 km) closely follows the thunderstorm activities. Concentric GWs can no longer be observed hours after the diminishment of the corresponding thunderstorms. With the nearby background wind measured by a median frequency (MF) radar, intrinsic wave parameters and associated vertical wavelengths can be calculated, leading to the estimation of the cancellation factor for the airglow intensity perturbation. The horizontal wavelengths of GWs from the same source decreases with time following the dispersion relation. A convective plume model and a ray trace model are used to simulate the concentric GWs-induced intensity perturbation in the airglow layer from hundreds of convective plumes at this night. Model result with the actual radiosonde/TIME-GCM model wind is more comparable to the observations, than that with a zero wind environment. Doppler shift effect by the horizontal wind makes the wave patterns asymmetric and enhances the airglow intensity perturbation by short wavelength GWs.

  9. Atmospheric structure and variability in areas of convective storms determined from 3-h rawinsonde data 

    E-print Network

    Wilson, Gregory Sims

    1975-01-01

    Atmospheric Variability Experiment (AVE II) conducted on 11 and 12 Nay 1974, Con~ective activity is shown to exist in areas where the low and middle troposphere is moist, the air is potentially and convectively unstable, and has upward motion... of rawinsonde stations for AVE II Locations of surface stations in AVE II Manually digitized radar (MDR) grid network Synoptic charts for 1800 GMT, 11 May 1974 Synoptic charts for 0600 GMT, 12 May 1974 Grid used for numerical computations 10 12 15 19...

  10. Overview of ESSL's severe convective storms research using the European Severe Weather Database ESWD

    NASA Astrophysics Data System (ADS)

    Dotzek, Nikolai; Groenemeijer, Pieter; Feuerstein, Bernold; Holzer, Alois M.

    Severe thunderstorms constitute a major weather hazard in Europe, with an estimated total damage of 5-8 billion euros each year nowadays. Even though there is an upward trend in damage due to increases in vulnerability and possibly also due to climate change impacts, a pan-European database of severe thunderstorm reports in a homogeneous data format did not exist until a few years ago. The development of this European Severe Weather Database (ESWD) provided the final impetus for the establishment of the European Severe Storms Laboratory (ESSL) as a non-profit research organisation in 2006, after having started as an informal network in 2002. Our paper provides an overview of the first research results that have been achieved by ESSL. We start by outlining the reporting practice and quality-control procedure for the database, which has been enhanced by a major software upgrade in the fall of 2008. It becomes apparent that the state of reporting converges to a realistic description of the severe storms climatology, corroborating, for instance, earlier estimates of tornado occurrence in Europe. Nevertheless, a further rise in the number of reported events must be expected, even without the presence of any physical trends. The European tornado and damaging wind intensity distributions as a function of the Fujita scale are quantitatively similar to long-term distributions from the USA, except for a strong underreporting of weak events (F0) that still persists in Europe. In addition, the ESSL has recently proposed a new wind speed scale, the Energy- or " E-scale" which is linked to physical quantities and can be calibrated. Finally, we demonstrate the large potential of ESWD data use for forecast or nowcasting/warning verification purposes.

  11. 13A.1 ASSIMILATION OF SIMULATED NETWORK RADAR DATA OF VARIED STORM TYPES USING ENSRF FOR CONVECTIVE STORM ANALYSES AND FORECASTS

    E-print Network

    Xue, Ming

    installation costs down, the CASA radars will be placed on cell phone towers or other existing infras- tructure of perturbed observations. This study assesses the potential effects of assimilating radar data on storm.) for individual super- cell storms, even though radars do not directly observe these variables (XTD05b). In TX05

  12. Severe Storms

    NSDL National Science Digital Library

    2010-01-01

    Part of the University of Illinois Weather World 2010 project, this guide uses multimedia technology and the dynamic capabilities of the web to incorporate text, colorful diagrams, animations, computer simulations, audio, and video to introduce topics and concepts in the atmospheric sciences. This module is a combination of two elements. The first is the National Oceanic and Atmospheric Administration (NOAA) Severe Storms Spotters Guide. The second is a section discussing the efforts and results of modeling severe storms. The Spotters Guide contains supplemental instructional resources and a program designed to familiarize meteorologists and advanced severe storm spotters with the building blocks of convective storm structure. The focus of the training series is the development of a thunderstorm spectrum and a discussion of the physical characteristics and severe weather potential of the various storm types in the spectrum.

  13. Evaluating the importance of convective intensity and symmetry as predictors of TC intensity change for a large database of storms in favorable environments

    NASA Astrophysics Data System (ADS)

    Alvey, G., III; Zawislak, J.; Zipser, E. J.

    2014-12-01

    Despite operational advances in tropical cyclone track forecasts, progress towards improving forecasts of intensity change has been more limited. Previous studies have separately quantified the importance of environmental conditions and convective properties with respect to intensity change; however, conjoined analyses have been rare. Using 15 years (1998-2012) of SHIPS and NCEP FNL reanalysis information for Atlantic and East Pacific storms, we analyze the sensitivity of intensity change for a detailed set of environmental parameters. Environmental conditions are then used to determine a threshold beyond which intensification is plausible. In conjunction with the environmental dataset, an expansive collection of passive microwave satellite (includes TMI, AMSR-E, and SSMI[S]) and TRMM Precipitation Radar (PR) data is used to investigate the relative importance of various convective properties (specifically those proxies for convective intensity, symmetry, and area) in storms that meet the "plausible" threshold. An emphasis is placed on evaluating the hypothesis that, when a necessary set of environmental conditions is met, intensification is favored if the inner core consists of symmetric, moderately intense convection.

  14. Determination of Storm Flashing/Non-Flashing Condition From Convective and Environmental Observations

    NASA Technical Reports Server (NTRS)

    Boccippio, Dennis J.

    2002-01-01

    A simple and fundamental problem in cloud electrification is whether or not a cloud can be determined to be producing lightning or not producing lightning, based solely on knowledge of its microphysical (and perhaps environmental) state. A merged database of TRMM radar, microwave and lightning observations and NCEP reanalysis environmental parameters is used to answer this question, for the tropics. The formal skill of traditional, univariate rule-based approaches (e.g., 35 dBZ occurrence at 6 km altitude) is quantified (via the probability of detection (POD), false alarm rate (FAR) and critical skill index (CSI)). Under indiscriminate application to the tropics, peak rule-based CSI for categorization of flashing storms is approximately 50%, with peak POD approximately 67% and minimum FAR approximately 33%, with peak CSI found for radar reflectivity-based parameters at 7-7.5 km altitude (near -15C). Separation of land and ocean domains yields approximately 5-10% gains in CSI over land. Conventional multivariate categorization techniques (discriminant analysis) are then applied, and less conventional (neural network) categorization techniques are also discussed.

  15. Radar Observation of Large Attenuation in Convective Storms: Implications for the Dropsize Distribution

    NASA Technical Reports Server (NTRS)

    Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.

    2000-01-01

    Airborne meteorological radars typically operate at attenuating wavelengths. The path integrated attenuation (PIA) can be estimated using the surface reference technique (SRT). In this method, an initial value is determined for the radar cross section of the earth surface in a rain-free area in relatively close proximity to the rain cloud. During subsequent observations of precipitation any decrease 'in the observed surface cross section from the reference value s assumed to be a result of the two-way attenuation along the propagation path. In this paper we present selected instances of high PIA observed over land by an airborne radar. The observations were taken in Brazil and Florida during TRMM (Tropical Rainfall Measurement Mission) field campaigns. We compared these observations with collocated and nearly simultaneous ground-based radar observations by an S-band radar that is not subject to significant attenuation. In this preliminary evaluation, a systematic difference in the attenuation in the two storms is attributed to a difference in the raindrop size distributions; this is supported by observations of ZDR (differential reflectivity).

  16. Three-Dimensional Simulation of a Convective Storm: Sensitivity Studies on Subgrid Parameterization and Spatial Resolution.

    NASA Astrophysics Data System (ADS)

    Redelsperger, J. L.; Sommeria, G.

    1986-11-01

    This article presents the main features of a three-dimensional model for deep convection developed with special care given to the formulation of subgrid turbulent processes. It explicitly simulates the dynamics of turbulent eddies, including condensation and precipitation processes. Second-order moments are expressed as a function of the grid-averaged field of variables and of a prognostic turbulent kinetic energy. The formulation includes a simple statistical treatment of subgrid condensation and subgrid conversion of cloud water into rain water. The coherence and relative importance of the various closure hypotheses are tested in an idealized case of precipitating cloud.Results indicate the extent that features of the computed field are dependent on hypotheses used in the turbulence closure, choice of the basic turbulent variables, and formulation of the second-order moments. Significant benefits are obtained from the use of variables that are conserved in the condensation process. The computation of grid-scale condensation and precipitation is mostly dependent on the hypotheses made respectively for subgrid condensation and precipitation. Finally, it is shown that an advanced subgrid turbulence parameterization can partially compensate for the effects of a low spatial resolution.

  17. Skywarn Spotter Convective Basics

    NSDL National Science Digital Library

    2014-09-14

    The "SKYWARN® Spotter Convective Basics" module will guide users to a basic understanding of convective storms. Through three different scenarios, you will cover reporting and proper communication of local storm reports to the National Weather Service (NWS), personal safety during these events, and field identification of convective storm hazards. After completing the scenarios, you will be given the opportunity to practice identifying storm features from a spectrum of photos.

  18. The Impact on Simulated Storm Structure and Intensity of Variations in the Lifted Condensation Level and the Level of Free Convection

    NASA Technical Reports Server (NTRS)

    McCaul, Eugene W., Jr.; Cohen, Charles; Arnold, James E. (Technical Monitor)

    2001-01-01

    The sensitivities of convective storm structure and intensity to changes in the altitudes of the prestorm environmental lifted condensation level and level of free convection axe studied using a full-physics three-dimensional cloud model. Matrices of simulations are conducted for a range of LCL=LFC altitudes, using a single moderately-sheared curved hodograph trace in conjunction with 1 convective available potential energy values of either 800 or 2000 J/kg, with the matrices consisting of all four combinations of two distinct choices of buoyancy and shear profile shape. For each value of CAPE, the LCL=LFC altitudes are also allowed to vary in a series of simulations based on the most highly compressed buoyancy and shear profiles for that CAPE, with the environmental buoyancy profile shape, subcloud equivalent potential temperature, subcloud lapse rates of temperature and moisture, and wind profile held fixed. For each CAPE, one final simulation is conducted using a near optimal LFC, but a lowered LCL, with a neutrally buoyant environmental thermal profile specified in between. Results show that, for the buoyancy-starved small-CAPE environments, the simulated storms are supercells and are generally largest and most intense when LCL=LFC altitudes lie in the approximate range 1.5-2.5 km above the surface. The simulations show similar trends for the shear-starved large-CAPE environments, except that conversion from supercell to multicell morphology frequently occurs when the LCL is high. For choices of LCL=LFC height within the optimal 1.5-2.5 km range, peak storm updraft overturning efficiency may approaches unity relative to parcel theory, while for lower LCL=LFC heights, overturning efficiency is reduced significantly. The enhancements of overturning efficiency and updraft diameter with increasing LFC height are shown to be the result of systematic increases in the mean equivalent potential temperature of the updraft at cloud base. For the shear-starved environments, the tendency for outflow dominance is eliminated, but a large overturning efficiency maintained, when a low LCL is used in conjunction with a high LFC. The result regarding outflow dominance at high LCL is consistent with expectations, but the beneficial effect of a high LFC on convective overturning efficiency has not previously been widely recognized. The simulation findings here also appear to be consistent with statistics from previous severe storm environment climatologies, but provide a new framework for interpreting those statistics.

  19. Near-Surface Vortex Structure in a Tornado and in a Sub-Tornado-Strength Convective-Storm Vortex Observed by a Mobile, W-Band Radar during VORTEX2

    E-print Network

    Xue, Ming

    Near-Surface Vortex Structure in a Tornado and in a Sub-Tornado-Strength Convective-Storm Vortex Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) field campaign, a very high-resolution, mobile, W-band Doppler radar collected near-surface (#200 m AGL) observations in an EF-0 tornado near

  20. Effects of acid deposition on dissolution of carbonate stone during summer storms in the Adirondack Mountains, New York, 1987-89

    USGS Publications Warehouse

    Schuster, Paul F.; Reddy, Michael M.; Sherwood, S.I.

    1994-01-01

    This study is part of a long-term research program designed to identify and quantify acid rain damage to carbonate stone. Acidic deposition accelerates the dissolution of carbonate-stone monuments and building materials. Sequential sampling of runoff from carbonate-stone (marble) and glass (reference) microcatchments in the Adirondack Mountains in New York State provided a detailed record of the episodic fluctuations in rain rate and runoff chemistry during individual summer storms. Rain rate and chemical concentrations from carbonate-stone and glass runoff fluctuated three to tenfold during storms. Net calcium-ion concentrations from the carbonatestone runoff, a measure of stone dissolution, typically fluctuated twofold during these storms. High net sulfate and net calcium concentrations in the first effective runoff at the start of a storm indicated that atmospheric pollutants deposited on the stone surface during dry periods formed calcium sulfate minerals, an important process in carbonate stone dissolution. Dissolution of the carbonate stone generally increased up to twofold during coincident episodes of low rain rate (less than 5 millimeters per hour) and decreased rainfall (glass runoff) pH (less than 4.0); episodes of high rain rate (cloudbursts) were coincident with a rapid increase in rainfall pH and also a rapid decrease in the dissolution of carbonate-stone. During a storm, it seems the most important factors causing increased dissolution of carbonate stone are coincident periods of low rain rate and decreased rainfall pH. Dissolution of the carbonate stone decreased slightly as the rain rate exceeded about 5 millimeters per hour, probably in response to rapidly increasing rainfall pH during episodes of high rain rate and shorter contact time between the runoff and the stone surface. High runoff rates resulting from cloudbursts remove calcium sulfate minerals formed during dry periods prior to storms and also remove dissolution products formed in large measure by chemical weathering as a result of episodes of low rain rate and decreased rainfall pH during a storm.

  1. The Cause of Geomagnetic Storms

    Microsoft Academic Search

    T. Nagatsuma

    2001-01-01

    Although the cause of magnetic storms is important issue, the exact mechanism of the storm development is still controversial. Two mechanisms of storm development are considered. One is that the frequent substorm activity injects high-energy particles to the inner magnetosphere; the other is that the enhanced convection plays a role. Further, Iyermori and Rao [1996] shows that the substorm reduces

  2. Warm Season Convective Storm Structures over the Northeastern U.S. and their Interaction with the Marine Environment

    NASA Astrophysics Data System (ADS)

    Lombardo, Kelly

    The evolution of organized convective structures over the northeastern U.S. from initiation to decay is influenced by a variety of geographical features (elevated terrain, coastal boundary). Warm season convection over this region has been relatively unexplored, especially the interaction between quasi-linear convective structures (QLCSs) and the marine environment. This thesis is the first study to systematically explore the evolving convective structures over the Northeast, with particular emphasis on the coastal region from New Jersey northeastward to Rhode Island, through observational analysis as well as high-resolution simulations of 2 representative case studies. Organized convective structures over the Northeast during the warm season (May--August) were identified and classified into 3 main groups, including cells, quasi-linear convection, and nonlinear structures. Across the Northeast, the occurrence of all convection decreases from the western Appalachian slopes eastward to the Atlantic coast. Composite analysis highlights the importance of terrain during the initiation of cellular convection, with a majority developing in orographically-favored upslope areas. Linear and nonlinear convection are dynamically supported with a weaker terrain influence. Composite analyses reveal that QLCSs that decay upon encountering the Atlantic coastline organize along a surface pressure trough, collocated with a region of low-level frontogenesis. Those that maintain their intensity organize downstream of a surface trough within low-level warm air advection with higher saturation in the lowest 100 hPa compared to decaying events. Sensitivity studies of a representative decaying linear event illustrate that evaporative cooling causes the development of a strong a cold pool that overwhelms the weak ambient vertical wind shear downwind of the system causing the system to decay. During this event, the role of the marine layer appears secondary. For the maintaining event, the marine layer allows the magnitude of the surface winds to be larger compared to the land due to decreasing surface friction, which increases the vertical wind shear and helps to maintain the convection. Sensitivity tests show that by increasing the roughness length over the ocean to an equivalent land value, thus decreasing vertical wind shear, the maintaining event decays closer to the coastline compared to the control run.

  3. Multiparameter Radar Observations of Time Evolution of Convective Storms: Evaluation of Water Budgets and Latent Heating Rates

    Microsoft Academic Search

    Hui Tong; V. Chandrasekar; K. R. Knupp; James Stalker

    1998-01-01

    One advantage of dual-polarization radars is the ability to differentiate between water and ice phases in storms. The application of difference reflectivity ( ZDP) in the analysis of mixed-phase precipitation is presented. Here, ZDP analysis is used to obtain the fraction of water and ice in mixed-phase precipitation. The techniques developed are applied to data collected on 9 August 1991

  4. Satellite detection of severe convective storms by their retrieved vertical profiles of cloud particle effective radius and

    E-print Network

    Daniel, Rosenfeld

    . The respective roles of convective potential available energy (CAPE) and the 0­6 km vertical wind shear have been of the wind shear are major modulating factors, it appears that they are manifested in the updraft intensity as having wind gusts >58 mph, hail >3/4 inch (1 inch = 2.54 cm) in diameter, or producing tornadoes. A major

  5. HEAT TRANSFERS IN A DOUBLE SKIN ROOF VENTILATED BY NATURAL CONVECTION IN SUMMER TIME

    E-print Network

    Boyer, Edmond

    internal and external surface emissivity, the insulation thickness and the inclination angle for a channel. Temperature and air velocity profiles on several channel cross sections are plotted and discussed. Keywords passive cooling of dwellings and can help diminishing power costs for air conditioning in summer

  6. Characteristics of Precipitating Convective Systems Accounting for the Summer Rainfall of Tropical and Subtropical South America

    E-print Network

    Houze Jr., Robert A.

    and Subtropical South America ULRIKE ROMATSCHKE AND ROBERT A. HOUZE JR. University of Washington, Seattle of the precipitating cloud systems that account for the summer rainfall of tropical and subtropical South America role in the meteorology, climatology, and hydrology of South America. They not only produce

  7. Characterization of mesoscale convective systems over the eastern Pacific during boreal summer

    NASA Astrophysics Data System (ADS)

    Berthet, Sarah; Rouquié, Bastien; Roca, Rémy

    2015-04-01

    The eastern Pacific Ocean is one of the most active tropical disturbances formation regions on earth. This preliminary study is part of a broader project that aims to investigate how mesoscale convective systems (MCS) may be related to these synoptic disturbances with emphasis on local initiation of tropical depressions. As a first step, the main characteristics of the MCS over the eastern Pacific are documented with the help of the recently developed TOOCAN tracking algorithm (Fiolleau and Roca, 2013) applied to the infrared satellite imagery data from GOES-W and -E for the period JJAS 2012-2014. More specifically, the spatial distribution of the MCS population, the statistics of their spatial extensions and durations, as well as their trajectories and propagation speeds are summarized. In addition the environment of the MCS will be investigated using various Global Precipitation Mission datasets and the Megha-Tropiques/SAPHIR humidity microwave sounder derived products. Reference: Fiolleau T. and R. Roca, (2013), An Algorithm For The Detection And Tracking Of Tropical Mesoscale Convective Systems Using Infrared Images From Geostationary Satellite, Transactions on Geoscience and Remote Sensing, doi: 10.1109/TGRS.2012.2227762.

  8. VHF radar observed characteristics of convectively generated gravity waves during wet and dry spells of Indian summer monsoon

    NASA Astrophysics Data System (ADS)

    Uma, K. N.; Kishore Kumar, Karanam; Narayana Rao, T.

    2011-05-01

    A powerful VHF radar observed characteristics of Convectively generated Gravity Waves (CGW) excited during the wet and dry spells of Indian summer monsoon over a tropical station Gadanki (13.5°N, 79.2°E) are discussed. The characteristics of gravity waves in the lower stratosphere during these two spells are discussed in terms of their wavelet spectra along with height-time sections of vertical velocity. A total of 31 events are analyzed and in more than 50% of the events, the lower stratospheric gravity wave amplitudes were found to be relatively large in dry spell compared to that in the wet spell. The wavelet analysis of lower stratospheric vertical velocities showed a dominant periodicity of about ˜20-40 min in wet spell and ˜10-20 min in dry spell. The analysis also indicates that wet spell is found to be more conducive for the generation of gravity waves. However, the propagation of these waves into the stratosphere is found to be more efficient in dry spell of monsoon. The strengthening/weakening of the tropical easterly jet during wet/dry spell of monsoon is found to be the main reason for the inhibited/enhanced wave activity in the lower stratosphere during wet/dry spell. The present analysis also suggests that the static stability of the mid- and upper-troposphere during these two spells have implications in the observed frequency of the CGW. Thus, the present analyses brought out for the first time the features of CGW during two distinctive regimes of convective systems and emphasized the importance of prevailing background conditions in exciting/filtering them.

  9. Thyroid storm

    MedlinePLUS

    Thyrotoxic storm; Hyperthyroid storm; Accelerated hyperthyroidism ... Thyroid storm occurs in people with untreated hyperthyroidism. It is usually brought on by a major stress such as trauma, heart attack, or infection. Thyroid storm is very rare.

  10. Roles of the tropical convective activities over different regions in the earlier onset of the South China Sea summer monsoon after 1993

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Chen, Wen

    2013-07-01

    The South China Sea summer monsoon (SCSSM) onset experiences evidently an interdecadal change around mid-1990s. Generally, the SCSSM broke out half a month earlier during 1994-2010 than IN 1978-1993. Possible causes are analyzed in this study. The results suggest that the earlier onset of the SCSSM is due to earlier retreat of the subtropical high (STH) over the western Pacific, which is closely related to enhanced intraseasonal oscillations of tropical convections. The enhanced convective activities can be found in three regions: the eastern tropical Indian Ocean (TIO), the equatorial SCS-Kalimantan (ESK) and the tropical western Pacific (TWP). Both convections in the TIO and the ESK are greatly influenced by the interaction of the westerly wind from the TIO and the easterly wind from the TWP. The convections in the TIO are never found to propagate to the east of 100°E, while those in the ESK are usually quite weak and not great help to the SCSSM onset. Our results suggest that the earlier retreat of the STH is mainly caused by the enhanced convections in the TWP, while the later may be the consequence of warming over the TWP on the interdecadal timescale. Therefore, the La Niña-like interdecadal change of the sea surface temperature (SST) in the Pacific is likely to be responsible for the interdecadal advance of the SCSSM onset.

  11. What is a geomagnetic storm?

    Microsoft Academic Search

    W. D. Gonzales; J. A. Joselyn; Y. Kamide; H. W. Kroehl; G. Rostoker; B. T. Tsurutani; V. M. Vasyliunas

    1994-01-01

    The authors present a review of geomagnetic storm research. They examine the interaction of the solar wind with the magnetosphere. They argue that a storm results from the extended interaction of the solar wind\\/magnetosphere when a strong convection electric field is generated, which is able to perturb the ring current above some threshold level, triggering the event. They touch on

  12. Sand Storm 

    E-print Network

    Unknown

    2011-09-05

    of four hours of model output from the mature stage of the storm system was produced for quantitative comparison to the instanta- neous model storm at the central time of the composite. Additionally, the composite model storm was compared to the ob...- served composite storm. This comparison showed that the model used in the numerical simulation reproduced many of the features observed in the actual storm. However, the composite model and observed composite storms differed mainly near the melting...

  13. Inertia gravity waves associated with deep convection observed during the summers of 2005 and 2007 in Korea

    NASA Astrophysics Data System (ADS)

    Ki, Mi-Ok; Chun, Hye-Yeong

    2011-08-01

    Characteristics of inertia gravity waves associated with convection are investigated in the lower stratosphere using high-resolution radiosonde data observed from 18 June to 15 July of 2005 and 2007 in Korea. Three-dimensional ray-tracing model and reanalysis data are used to investigate the propagation and the sources of the observed waves. The observed waves associated with convections are discriminated based on the existence of convections when and where the rays reach the average height range of convective clouds. Waves observed in 2005 and 2007 show similar spectral characteristics, but wave energy in 2007 is significantly larger than in 2005. The observed waves propagate from three source regions: the northeastern, southeastern, and western regions around Korea. They show preferential propagation directions based on their sources, and convections from the western region generate larger-amplitude gravity waves than the other two regions. The spectral characteristics of the observed waves are determined largely by those of the convective forcing, along with the wave propagation condition associated with background wind and stability. The significantly larger mean wave energy in 2007 occurs because more observed waves originate from the western region of Korea in 2007 than in 2005 where convective forcing is much larger than in the other source regions.

  14. Differences in Fine- Coarse Aerosol Ratios in Convective and Non-Convective Dust Events in a Desert City

    NASA Astrophysics Data System (ADS)

    Gill, T. E.; Rivera Rivera, N. I.; Novlan, D. J.

    2014-12-01

    El Paso, Texas (USA) and Ciudad Juarez, Chihuahua (Mexico) form the Paso del Norte, the largest metropolitan area in North America's Chihuahuan Desert. The cities are subject to frequent dust storms presenting a hazard to local infrastructure and health, including synoptic-scale dust events during winter and spring, and dusty outflows from convective storms (haboobs) primarily during the summer. We evaluate particulate matter (PM2.5 and PM10) concentrations over a decade of convective and non-convective dust events, based on hourly aerosol data collected by Texas Commission on Environmental Quality (TCEQ) continuous air monitors in El Paso cross-referenced to weather observations from the USA National Weather Service. A total of 219 dust events (95 convective and 124 non-convective) events occurred between 2001 and 2010. The PM2.5/PM10 ratio was significantly higher (proportionally greater concentration of fine aerosols) in convective episodes and during summertime events than during non-convective dust events and dust episodes in other seasons, although overall concentrations of both PM2.5 and PM10 were higher in the non-convective events, which were also longer-lasting. These differences in fine/coarse aerosol ratios are likely related to different atmospheric stability conditions, and/or different mechanisms of dust particle entrainment and transport in haboobs versus non-convective dust events. Since visibility degradation and adverse human health effects are known to be exacerbated by to fine aerosol concentrations, thunderstorm-related dust events may present a proportionally greater hazard.

  15. Winter Storms

    NSDL National Science Digital Library

    1996-01-01

    This site offers general background about winter storms as well as interactive activities to teach visitors about these storms. It also offers a teachers guide to using this site and links to other weather-related pages. There are four main topics: All About Winter Storms, Interactive Weather Maker, Interactive Winter Storm Timeline, and Ask Our Winter Storm Expert. All About Winter Storms gives general background information an a glossary of weather terms. The Weather Maker offers students a chance to control the weather through a simulation in which they affect the weather by changing variables such as humidity, equatorward temperature, and polarward temperature. The Storm Timeline offers students a chance to move up and down the timeline to learn about past winter storms. In Ask the Expert, students can email their questions to a winter storm expert and have them answered. This section also gives a brief biography of the expert.

  16. Storm Prediction Center

    NSDL National Science Digital Library

    The Storm Prediction Center (SPC) is an agency of the National Oceanic and Atmospheric Administration (NOAA) National Weather Service. Materials available on the website include current weather watches, mesoscale discussions, convective outlooks, six-hour thunderstorm outlooks, and fire weather forecasts; research publications, experimental products and techniques; weather information including watch/warning maps, climatological data, and current radar; and a section on tornadoes. There is also an archive of weather images, and sections on the organization and history of the Center.

  17. Orographic effects related to deep convection events over the Andes region

    NASA Astrophysics Data System (ADS)

    Hierro, R.; Pessano, H.; Llamedo, P.; de la Torre, A.; Alexander, P.; Odiard, A.

    2013-02-01

    In this work, we analyze a set of 39 storms which took place between 2006 and 2011 over the South of Mendoza, Argentina. This is a semiarid region situated at mid-latitudes (roughly between 32S and 36S) at the east of the highest Andes tops which constitutes a natural laboratory where diverse sources of gravity waves usually take place. We consider a cultivated subregion near San Rafael district, where every summer a systematic generation of deep convection events is registered. We propose that the lift mechanism required to raise a parcel to its level of free convection is partially supplied by mountain waves (MWs). From Weather Research and Forecasting (WRF) mesoscale model simulations and radar network data, we calculate the evolution of convective available potential energy and convective inhibition indices during the development of each storm. Global Final Analysis is used to construct initial and boundary conditions. Convective inhibition indices are compared with the vertical kinetic energy capable of being supplied by the MWs, in order to provide a rough estimation of this possible triggering mechanism. Vertical velocity is chosen as an appropriate dynamical variable to evidence the presence of MWs in the vicinity of each detected first radar echo. After establishing a criterion based on a previous work to represent MWs, the 39 storms are split into two subsets: with and without the presence of MWs. 12 cases with considerable MWs amplitude are retained and considered. Radar data differences between the two samples are analyzed and the simulated MWs are characterized.

  18. Polarimetric and Multi-Doppler Radar Observations of Sprite-producing Storms

    NASA Technical Reports Server (NTRS)

    Lang, TImothy J.; Lyons, Walter A.; Rutledge, Steven A.; Dolan, Brenda; Cummer, Steven A.; Krehbiel, Paul; Rison, William

    2014-01-01

    Sprites are caused by luminous electrical breakdown of the upper atmosphere, and frequently occur over large mesoscale precipitation systems. Two sprite-producing storms (on 8 and 25 June) were observed in Colorado during the summer of 2012. Unlike most past studies of sprites, these storms were observed by a polarimetric radar - the CSU-CHILL facility - which provided both PPI and RHI scans of the cases. Also available were multiple-Doppler syntheses from CSU-CHILL, local NEXRAD radars, and the CSU-Pawnee radar; as well as data from the Colorado Lightning Mapping Array (COLMA), high speed cameras, and other lightning-detection instrumentation. This unique dataset provided an unprecedented look at the detailed kinematic and microphysical structures of the thunderstorms as they produced sprites, including electrical alignment signatures in the immediate location of the charge layers neutralized by sprite-parent positive cloud-to-ground lightning strokes. One of the sprite-producing cases (25 June) featured an anomalous charge structure and may serve as a model for how sprites can be produced over convection rather than the more typical stratiform regions. Also to be presented will be evidence for advection of charge into a common stratiform precipitation region (on 8 June), which was then tapped by lightning originating from multiple different convective cores to produce sprites. Depending on the outcome of the 2013 convective season, polarimetric data from additional storms that produce sprites and other transient luminous events (TLEs) may be presented.

  19. Explosive supercell growth - A possible indicator for tropical storm intensification?

    NASA Technical Reports Server (NTRS)

    Venne, Monique G.; Lyons, Walter A.; Keen, Cecil S.; Black, Peter G.; Gentry, R. Cecil

    1989-01-01

    Several tropical storm observations are discussed which support the hypothesis that bursts of cloud-to-ground lightning near the center of a developing tropical storm (also called convective exhaust clouds and supercells), indicative of organized deep convection, could provide a valuable diagnostic for intensification over the next 12-36 hours. It is emphasized that further research is required in order to establish the exact role of supercells in tropical storm intensification.

  20. 13.2 A REPORT AND FEATURE-BASED VERIFICATION STUDY OF THE CAPS 2008 STORM-SCALE ENSEMBLE FORECASTS FOR SEVERE CONVECTIVE WEATHER

    E-print Network

    analyzed as guidance for operational forecasts of high-impact, convective weather events. Probabilities Ensemble forecasts of high-impact, rare weather events generated from models that explicitly resolve density, nonhydrostatic numerical models at fine resolutions (i.e., 4 km grid spacing) that are capable

  1. Total Storm Currents in Relation to Storm Type and Lifecycle

    NASA Astrophysics Data System (ADS)

    Deierling, W.; Kalb, C. P.; Mach, D. M.; Liu, C.

    2013-12-01

    Electrified lightning and non-lightning producing clouds of various types are thought to play a major role in supplying current to the global electric circuit (GEC). However, the contribution of storm conduction currents of different cloud types to the GEC is still not entirely known. Estimates of storm total conduction currents for different electrified clouds for the general categories of oceanic and continental electrified clouds were recently estimated from data collected over two decades during multiple field campaigns involving the NASA ER-2 and Altus-II aircraft. Building on this previous work, in this study we differentiate cloud categories into more specific cloud types (e.g. convective and stratiform partitions, severe versus ordinary single cell storms) and investigate on a case by case basis their underlying microphysical and dynamical structure. We also investigate the temporal evolution of storm total conduction currents during the lifecycle of electrified clouds.

  2. Impact of domain size on the simulation of Indian summer monsoon in RegCM4 using mixed convection scheme and driven by HadGEM2

    NASA Astrophysics Data System (ADS)

    Dash, S. K.; Pattnayak, K. C.; Panda, S. K.; Vaddi, Deepika; Mamgain, Ashu

    2015-02-01

    In this study, a smaller domain over India alone and a larger South Asia (SA) domain have been used in the Regional Climate Model version 4.2 (RegCM4.2) to examine the effect of the domain size on the Indian summer monsoon simulations. These simulations were carried out over a period of 36 years at 50 km horizontal resolution with the lateral boundary forcings of the UK Met Office Hadley Centre Global Circulation Model Version 2.0. Results show that the Indian summer monsoon rainfall is significantly reduced when the domain size for the model integration is reduced from SA to the Indian domain. In case of SA domain simulation, the Equitable Threat Scores have higher values in case of very light, light and moderate rainfall events than those in case of the Indian domain simulation. It is also found that the domain size of model integration has dominant impact on the simulated convective precipitation. The cross-equatorial flow and the Somali Jet are better represented in the SA simulation than those in the Indian domain simulation. The vertically integrated moisture flux over the Arabian Sea in the SA domain simulation is close to that in the NCEP/NCAR reanalysis while it is underestimated in the Indian domain simulation. It is important to note that when RegCM4.2 is integrated over the smaller Indian domain, the effects of the Himalayas and the moisture advection from the Indian seas are not properly represented in the model simulation and hence the monsoon circulation and associated rainfall are underestimated over India.

  3. What is a geomagnetic storm?

    NASA Technical Reports Server (NTRS)

    Gonzalez, W. D.; Joselyn, J. A.; Kamide, Y.; Kroehl, H. W.; Rostoker, G.; Tsurutani, B. T.; Vasyliunas, V. M.

    1994-01-01

    After a brief review of magnetospheric and interplanetary phenomena for intervals with enhanced solar wind-magnetosphere interaction, an attempt is made to define a geomagnetic storm as an interval of time when a sufficiently intense and long-lasting interplanetary convection electric field leads, through a substantial energization in the magnetosphere-ionosphere system, to an intensified ring current sufficiently strong to exceed some key threshold of the quantifying storm time Dst index. The associated storm/substorm relationship problem is also reviewed. Although the physics of this relationship does not seem to be fully understood at this time, basic and fairly well established mechanisms of this relationship are presented and discussed. Finally, toward the advancement of geomagnetic storm research, some recommendations are given concerning future improvements in monitoring existing geomagnetic indices as well as the solar wind near Earth.

  4. Hail Storms

    NSDL National Science Digital Library

    Gene Moore

    This website contains photos and information about hail and hail storms as a weather phenomenon. The images show hail stones, storms with falling hail, cloud formations, and damage from hail. Each photo has a description with information about the weather system and occurrence of hail.

  5. The Role of Convection in Redistributing Formaldehyde to the Upper Troposphere Over North America and the North Atlantic during the Summer 2004 INTEX Campaign

    NASA Technical Reports Server (NTRS)

    Fried, Alan; Olson, Jennifer R.; Walega, Jim; Crawford, Jim H.; Chen, Gao; Weibring, Petter; Richter, Dirk; Roller, Chad; Tittel, Frank; Porter, Michael; Fuelberg, Henry; Halland, Jeremy; Bertram, Timothy H.; Cohen, Ronald C.; Pickering, Kenneth; Heikes, Brian G.

    2007-01-01

    Measurements of CH2O from a tunable diode laser absorption spectrometer (TDLAS) were acquired onboard the NASA DC-8 during the summer 2004 INTEX-NA (Intercontinental Chemical Transport Experiment - North America) campaign to test our understanding of convection and production mechanisms in the upper troposphere (UT, 6-12-km) over continental North America and the North Atlantic Ocean. Point-by-point comparisons with box model calculations, when MHP (CH3OOH) measurements were available for model constraint, resulted in a median CH2O measurement/model ratio of 0.91 in the UT. Multiple tracers were used to arrive at a set of UT CH2O background and perturbed air mass periods, and 46% of the TDLAS measurements fell within the latter category. At least 66% to 73% of these elevated UT observations were caused by enhanced production from CH2O precursors rather than direct transport of CH2O from the boundary layer. This distinction is important, since the effects from the former can last for over a week or more compared to one day or less in the case of convective transport of CH2O itself. In general, production of CH2O from CH4 was found to be the dominant source term, even in perturbed air masses. This was followed by production from MHP, methanol, PAN type compounds, and ketones, in descending order of their contribution. In the presence of elevated NO from lightning and potentially from the stratosphere, there was a definite trend in the CH2O discrepancy, which for the highest NO mixing ratios produced a median CH2O measurement/model ratio of 3.9 in the 10-12-km range. Discrepancies in CH2O and HO2 in the UT with NO were highly correlated and this provided further information as to the possible mechanism(s) responsible. These discrepancies with NO are consistent with additional production sources of both gases involving CH3O2 + NO reactions, most likely caused by unmeasured hydrocarbons.

  6. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    article title:  Massive Dust Storm over Australia     View Larger Image ... and dry conditions caused a massive blanket of dust from Australia's Outback to spread eastward across Queensland and New South Wales. ...

  7. Magnetic Storms

    NSDL National Science Digital Library

    2012-08-03

    This is a lesson to introduce the Kp index, a common numerical indicator of magnetic storminess. Learners will access and analyze Kp index plots of magnetic storm strength and determine the relative frequency of stronger versus weaker magnetic storms during years of maximum solar activity. This resource is activity 13 from the Magnetic Mysteries of the Aurora teachers guide. Internet access is required for this activity.

  8. EXTRATROPICAL SYNOPTIC-SCALE PROCESSES AND SEVERE CONVECTION

    E-print Network

    Doswell III, Charles A.

    EXTRATROPICAL SYNOPTIC-SCALE PROCESSES AND SEVERE CONVECTION Chapter 2 in Severe Convective Storms perspective of the interaction between severe convection and extratropical synoptic-scale processes severe convection develops (see, e.g., Newton 1963; Barnes and Newton 1983; Johns and Doswell 1992

  9. Gravity wave initiated convection

    NASA Astrophysics Data System (ADS)

    Hung, R. J.

    1990-09-01

    The vertical velocity of convection initiated by gravity waves was investigated. In one particular case, the convective motion-initiated and supported by the gravity wave-induced activity (excluding contributions made by other mechanisms) reached its maximum value about one hour before the production of the funnel clouds. In another case, both rawinsonde and geosynchronous satellite imagery were used to study the life cycles of severe convective storms. Cloud modelling with input sounding data and rapid-scan imagery from GOES were used to investigate storm cloud formation, development and dissipation in terms of growth and collapse of cloud tops, as well as, the life cycles of the penetration of overshooting turrets above the tropopause. The results based on these two approaches are presented and discussed.

  10. High-Resolution Modeling of the Predictability of Convective Systems, and Influences by Absorbing Aerosols Over Northern India and the Himalayas Foothills During Boreal Summer

    NASA Technical Reports Server (NTRS)

    Kim, Kyu-Myong; Lau, William K.-M.; Tao, Wei-Kuo; Shi, Jainn; Tan, Qian; Chin, Mian; Matsui, Toshihisa; Bian, Huisheng

    2011-01-01

    The Himalayas foothills region (HFR) is an important component of the South Asian monsoon. To the south, the HFR borders the fertile, populous, and heavily polluted Indo-Gangetic Plain (IGP). To the north, it rises to great height (approx. 4-5 km) to the Tibetan Plateau over a distance of less than 100 km. The HFR itself consists of complex mountainous terrain, with strong orographic forcing for precipitation. During the late spring and early summer, dust aerosol from the Thar and Middle East deserts , as well as moisture from the Arabian Sea were transported to the western part of the western part of the IGP and foothills spurs pre-monsoon severe thunderstorm over the region. During the monsoon season (mid June -August) convection from the Bay of Bengal, spread along the foothills northwestward to northern Pakistan. Recent climate model studies and preliminary observations have indicted not only the importance of dynamical forcing of precipitation in the HFR, but also possible strong impacts by the dense aerosols, from both local sources, and remote transport, that blanket the IGP from late spring up to the onset of the monsoon in June, and during monsoon breaks in July. In this work, we use the NASA Unified Weather Research and Forecasting (Nu-WRF) model to study the predictability ( 1-7 days) South Asian monsoon rainfall system. Results of 7 -day forecast experiments using an embedded domain of 27 km and 9 km resolution were conducted for the period June 11- July 15, 2008, with and without aerosol forcing are carried out to assess the intrinsic predictability of rainfall over the HFR, and possible impacts by aerosol direct effect, and possible connection of large-scale South Asian monsoon system.

  11. Observations of storm-induced mixing and Gulf Stream Ring incursion over the southern flank of Georges Bank: Winter and summer 1997

    NASA Astrophysics Data System (ADS)

    Lee, Craig M.; Brink, Kenneth H.

    2010-08-01

    High-resolution hydrographic measurements collected along the southern edge of Georges Bank during March and June-July 1997 focused on characterizing processes that drive fluxes of material between the slope and bank. Wintertime sampling characterized changes driven by a strong storm. A Scotian Shelf crossover event produced a ribbon of anomalously fresh water along the bank's southern flank that was diluted during the storm. Comparison of prestorm and poststorm sections shows that over the bank changes in heat and salt inventories are consistent with those expected solely from local surface fluxes. In deeper waters, advective effects, likely associated with frontal motion and eddies, are clearly important. Summertime surveys resolve the development of a massive intrusion of Gulf Stream-like waters onto the bank. East of the intrusion, a thin extrusion of bank water is drawn outward by the developing ring, exporting fresher water at a rate of about 7 × 104 m3/s. A large-amplitude Gulf Stream meander appears to initiate the extrusion, but it quickly evolves, near the bank edge, into a warm core ring. Ring water intrudes to approximately the 80 m isobath, 40 km inshore from the bank edge. The intrusion process seems analogous to the development of Gulf Stream shingles (a hydrodynamic instability) in the South Atlantic Bight. It appears that, once the intruded water is established on the bank, it remains there and dissipates in place. Although the intrusion is an extremely dramatic event, it is probably not actually a major contributor to shelf edge exchanges over a seasonal time scale.

  12. Monitoring and Understanding Trends in Extreme Storms: State of Knowledge

    E-print Network

    Kunkel, Kenneth E.

    The state of knowledge regarding trends and an understanding of their causes is presented for a specific subset of extreme weather and climate types. For severe convective storms (tornadoes, hailstorms, and severe ...

  13. Radar studies of heavy convective rainfall in mountainous terrain

    NASA Astrophysics Data System (ADS)

    Landel, Gregoire; Smith, James A.; Baeck, Mary Lynn; Steiner, Matthias; Ogden, Fred L.

    1999-01-01

    Heavy rainfall, topography, storm motion, and storm evolution are closely linked for four storms that produced catastrophic flooding along the Front Range of the Rocky Mountains and the east slope of the Blue Ridge Mountains. Storms selected for detailed study in this paper are the Rapidan storm of June 27, 1995, the Fort Collins storm of July 28, 1997, the Buffalo Creek storm of July 12, 1996, and the Monocacy storm of June 18, 1996. The Buffalo Creek storm and the Fort Collins storm occurred in the Front Range of the Rocky Mountains in Colorado; the Rapidan and Monocacy storms occurred along the east slopes of the Blue Ridge of Virginia and southern Pennsylvania. The four storms caused catastrophic flooding at drainage basin scales between 1 and 1000 km2. The scale of flood response for these events imposes a need to characterize rainfall variability at very fine space scales and timescales, of the order of 1 km spatial scale and 1-5 min timescale. A fundamental issue for the hydrometeorology of extreme rainfall in mountainous terrain is whether anomalously large rainfall accumulations in orographic convection result from anomalously slow net storm motion, anomalously large rainfall rates, or both. Anomalous storm motion and processes resulting in catastrophic rainfall rates are examined for each of the four storms. Of particular importance for anomalous storm motion in orographic convection are interactions between the low-level wind field and terrain features.

  14. Tropical Storm Erin

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Location: The Atlantic Ocean 210 miles south of Galveston, Texas Categorization: Tropical Storm Sustained Winds: 40 mph (60 km/hr)

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Infrared ImageMicrowave Image

    Infrared Images Because infrared radiation does not penetrate through clouds, AIRS infrared images show either the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. In cloud-free areas the AIRS instrument will receive the infrared radiation from the surface of the Earth, resulting in the warmest temperatures (orange/red).

    Microwave Images In the AIRS microwave imagery, deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. On the other hand, land appears much warmer due to its high radiation emissivity.

    Microwave radiation from Earth's surface and lower atmosphere penetrates most clouds to a greater or lesser extent depending upon their water vapor, liquid water and ice content. Precipitation, and ice crystals found at the cloud tops where strong convection is taking place, act as barriers to microwave radiation. Because of this barrier effect, the AIRS microwave sensor detects only the radiation arising at or above their location in the atmospheric column. Where these barriers are not present, the microwave sensor detects radiation arising throughout the air column and down to the surface. Liquid surfaces (oceans, lakes and rivers) have 'low emissivity' (the signal isn't as strong) and their radiation brightness temperature is therefore low. Thus the ocean also appears 'low temperature' in the AIRS microwave images and is assigned the color blue. Therefore deep blue areas in storms show where the most precipitation occurs, or where ice crystals are present in the convective cloud tops. Outside of these storm regions, deep blue areas may also occur over the sea surface due to its low radiation emissivity. Land appears much warmer due to its high radiation emissivity.

    Visible/Near-Infrared Images The AIRS instrument suite contains a sensor that captures radiation in four bands of the visible/near-infrared portion of the electromagetic spectrum. Data from three of these bands are combined to create 'visible' images similar to a snapshot taken with your camera.

    The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments can make simultaneous observations all the way down to the Earth's surface, even in the presence of heavy clouds. With more than 2,000 channels sensing different regions of the atmosphere, the system creates a global, 3-D map of atmospheric temperature and humidity and provides information on clouds, greenhouse gases, and many other atmospheric phenomena. The AIRS Infrared Sounder Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

  15. STORMS PREDICTION: LOGISTIC REGRESSION VS RANDOM FOREST FOR UNBALANCED DATA

    E-print Network

    Villa-vialaneix, Nathalie

    is that the data set is extremely unbalanced: convective systems represent only 4% of the whole database; thereforeSTORMS PREDICTION: LOGISTIC REGRESSION VS RANDOM FOREST FOR UNBALANCED DATA Anne Ruiz classes. Introduction Predicting storms is a high challenge for the French meteorological group Météo

  16. The flywheel effect: Ionospheric currents after a geomagnetic storm

    Microsoft Academic Search

    W. Deng; T. L. Killeen; A. G. Burns; R. G. Roble

    1991-01-01

    In the period following a geomagnetic storm the high-latitude, magnetospheric-driven convection pattern is normally weak. However, the neutral circulation, set up by ion-neutral momentum coupling during the main phase of the storm, may continue for several hours after the storm has ended. This persistent neutral circulation has the potential to drive Hall currents for some hours. In this paper the

  17. Severe dust storms over the Arabian Peninsula: Observations and modeling

    NASA Astrophysics Data System (ADS)

    shalaby, ahmed

    2014-05-01

    Dust aerosols and dust storms have tremendous effects on human health and all development activities. Also atmospheric dust plays a major role in the Earth climate system by its interaction with radiation and clouds. Severe dust storms are considered the severest phenomena in the Arabian Peninsula, since they are occurring all the year round with maximum activity and frequency in Summer. The Regional Climate Model (RegCM4) has been used to simulate severe dust storms events in the Arabian Peninsula from 1998 up to 2011. This long period simulation shows a typical pattern and dynamical features of the large-scale severe dust storm in winter seasons and summer seasons. The Aerosol Optical Depth (AOD) from the model outputs have been compared against ground--base observations of three AERONET stations (i.e., Kuwait, Mazeria and Solar-Village) and daily space--based observations of MISR, Deepblue and OMI. The dynamical analysis of the large—scale severe dust storms reveal the difference between winter time storms and summer time storm. Winter time storm occurs when the cold air front in the north is coupled with the extension of the Red Sea trough from the south. However, the summer time storm is associated with strong Shamal wind that extend from northern Kuwait to the southern Arabian Peninsula.

  18. Tropical storm motion and structure in a fine mesh primitive equation model

    Microsoft Academic Search

    M. B. Mathur

    1992-01-01

    Summary Convective to planetary scale processes govern the motion and structure of tropical storms. A model with a high resolution and a large domain is required for accurate prediction of a storm's track and intensity. A series of integrations are performed using a primitive equation model and an initial state that defines a tropical storm that later developed into a

  19. On the meteorology of sprite-producing storms

    NASA Astrophysics Data System (ADS)

    Lang, T. J.; Rutledge, S. A.; Beavis, N.; Lyons, W. A.; Cummer, S. A.; Krehbiel, P. R.; Rison, W.; Hager, W. W.

    2012-12-01

    This paper reports on continuing research into improving our understanding the meteorology of sprite-producing thunderstorms. Emphasis will be placed on investigating the radar-observed and electrical structures of these systems. Highlights of the presentation will include placing three-dimensional lightning mapping data of sprite-parent discharges into the context of overall thunderstorm structure, and characterizing how thunderstorm behavior shapes the behavior of sprite-producing lightning. Additional work will demonstrate the key differences between thunderstorms and lightning that produce negative sprites and those that produce positive sprites, with sprite-producing and sprite-class negative lightning occurring mainly in the convective lines of large mesoscale precipitation systems, as opposed to positive sprite parents that typically come to ground in the stratiform regions of these systems. Multiple-Doppler and polarimetric radar data were obtained from two sprite-producing storms during the Colorado component of the Deep Convective Clouds and Chemistry (DC3) campaign in the summer of 2012. These data will be analyzed in the context of lightning mapping data to fill current knowledge gaps in sprite thunderstorm meteorology, as past research has mainly focused on radar datasets featuring less kinematic and microphysical information than what was available during DC3. The meteorology of other recent (2008-2012) sprite-producing cases will be analyzed as time allows.

  20. POCATELLO STORM DRAIN STUDY, BANNOCK COUNTY, IDAHO - 1979

    EPA Science Inventory

    The City of Pocatello (17040208) storm drains were sampled during a winter snowmelt period and during a summer rainstorm. Chemical analyses of the drain water indicated levels of suspended solids, total solids, Chemical Oxygen Demand, sodium, potassium, chloride, fluoride, arsen...

  1. DETECTING CONVECTIVE INITIATION FROM RADAR

    E-print Network

    Lakshmanan, Valliappa

    convection #12;Real time: Image at t0 #12;Real time: Image at t1 #12;Real time: Observed CI #12;Methodology CI is useful: As heads-up to forecasters (alert on new storms) To verify/validate model timing movement Then, do a neighborhood search Pixels above 35 dBZ with no pixel above 35 dBZ within 3km

  2. The effects of storms and storm-generated currents on sand beaches in Southern Maine, USA

    USGS Publications Warehouse

    Hill, H.W.; Kelley, J.T.; Belknap, D.F.; Dickson, S.M.

    2004-01-01

    Storms are one of the most important controls on the cycle of erosion and accretion on beaches. Current meters placed in shoreface locations of Saco Bay and Wells Embayment, ME, recorded bottom currents during the winter months of 2000 and 2001, while teams of volunteers profiled the topography of nearby beaches. Coupling offshore meteorological and beach profile data made it possible to determine the response of nine beaches in southern Maine to various oceanographic and meteorological conditions. The beaches selected for profiling ranged from pristine to completely developed and permitted further examination of the role of seawalls on the response of beaches to storms. Current meters documented three unique types of storms: frontal passages, southwest storms, and northeast storms. In general, the current meter results indicate that frontal passages and southwest storms were responsible for bringing sediment towards the shore, while northeast storms resulted in a net movement of sediment away from the beach. During the 1999-2000 winter, there were a greater percentage of frontal passages and southwest storms, while during the 2000-2001 winter, there were more northeast storms. The sediment that was transported landward during the 1999-2000 winter was reworked into the berm along moderately and highly developed beaches during the next summer. A northeast storm on March 5-6, 2001, resulted in currents in excess of 1 m s-1 and wave heights that reached six meters. The storm persisted over 10 high tides and caused coastal flooding and property damage. Topographic profiles made before and after the storm demonstrate that developed beaches experienced a loss of sediment volume during the storm, while sediment was redistributed along the profile on moderately developed and undeveloped beaches. Two months after the storm, the profiles along the developed beaches had not reached their pre-storm elevation. In comparison, the moderately developed and undeveloped beaches reached and exceeded their pre-storm elevation and began to show berm buildup characteristic of the summer months. ?? 2004 Elsevier B.V. All rights reserved.

  3. STORM TIDE SIMULATIONS FOR HURRICANE HUGO (1989): ON THE SIGNIFICANCE OF INCLUDING INLAND FLOODING AREAS

    E-print Network

    Central Florida, University of

    1989-01-01

    STORM TIDE SIMULATIONS FOR HURRICANE HUGO (1989): ON THE SIGNIFICANCE OF INCLUDING INLAND FLOODING Florida Orlando, Florida Summer Term 2004 #12;ABSTRACT In this study, storm tides are simulated element models with triangular elements are applied in order to simulate the storm tides, allow

  4. In Brief: Cassini images Saturn storm

    NASA Astrophysics Data System (ADS)

    Zielinski, Sarah

    2006-11-01

    The Cassini spacecraft has spotted an 8000-kilometer-wide, hurricane-like storm around Saturn's South Pole, NASA announced on 9 November. The storm has a dark `eye' at the South Pole along with eye-wall clouds and spiral arms, but it is not known if moist convection-the driver of hurricanes on Earth-drives the Saturn storm. A movie taken by Cassini's camera indicates that the winds are blowing clockwise at about 560 kilometers per hour. Although large storms have been observed on other planets in the past-most notably, Jupiter's Great Red Spot-this is the first storm found to have eye-wall clouds and a relatively calm center. Andrew Ingersoll, a member of Cassini's imaging team at the California Institute of Technology, Pasadena, said the storm looks like a hurricane but is not behaving like one. ``Whatever it is, we are going to focus on the eye of this storm and find out why it is there.''

  5. Seasonal and solar activity dependence of storm time TEC variations for a low latitude station Palehua

    NASA Astrophysics Data System (ADS)

    Subhadra Devi, P. K.; Unnikrishnan, K.; Venugopal, C.

    2011-08-01

    The enhancement and depletions of the total electron content (TEC) on storm days from the quiet day values are analysed for different seasons and solar activity conditions at Palehua, a low latitude station, during the period 1980-1991.Considering the dependence of enhancement in storm time TEC for positive storms with solar radio flux F10.7, a positive correlation is observed in winter and equinox. For negative storms, the correlation of depletion in storm time TEC with solar radio flux F10.7 is positive in equinox, but no such dependency is observed in summer. The intensity of storm (Ap) is found to be negatively correlated with enhancement in storm time TEC, in equinox, for positive storms. But no such dependency is shown in winter. For negative storms, the depletion in storm time TEC shows no dependency with Ap in equinox, but shows positive correlation in summer. Considering the dependence of enhancement of TEC on Dst max, a positive correlation is observed in winter and equinox for positive storms. For negative storms, the correlation between depletion in storm time TEC and Dst max is found to be positive for summer and equinox. A similar correlation study is carried out for time delay (?) of occurrence of maximum enhancement and depletion of TEC. The maximum and minimum percentage probability range of ?TEC and ? are also analysed by considering the data seasonally.

  6. Ongoing Studies of the Characteristics of Storms and Lightning Discharges Which Do and Do Not Produce Sprites

    NASA Astrophysics Data System (ADS)

    Lyons, W. A.; Cummer, S. A.; Stanley, M. A.

    2003-12-01

    Within a year after the first intentional ground and aircraft monitoring of sprites (1993), it had become apparent that this class of mesospheric transient luminous event was almost uniquely associated with positive polarity cloud-to-ground lightning strokes (+CGs). Yet not all +CGs, even those with high peak currents, produce sprites. Moreover, sprite parent +CGs (SP+CGs) tend to occur only in certain types of convective storm systems. On the U.S. High Plains, the SP+CGs are most common in the stratiform precipitation regions of mature mesoscale convective systems (MCSs) larger than 10-20x10**4 km**2. The summer 2000 Severe Thunderstorm Electrification and Precipitation Study (STEPS) produced the most complete database of coordinated low-light television (LLTV), 3-D lightning mapping array (LMA) and remote ELF transient data available to date. A major question is whether large charge moment changes are both a necessary and a sufficient condition for sprites? This presentation presents the results of a reanalysis of the STEPS database which, aided by ELF charge moment change estimates, has revealed substantially more events than in the original catalog. Particular attention is paid to charge moment changes in three major classes of storms, (1) MCSs with many SP+CGs in the stratiform region, (2) supercells with only sporadic sprite events during restricted portions of their life cycle, and (3) MCSs and supercell storms which, in spite of many +CGs, produce no transient luminous events. In addition, the characteristics of continuing currents in High Plains lightning discharges monitored using high speed video cameras (1000 fps) is compared with ELF/ULF measurements (Courtesy: Martin Fullekrug). Additional observations of sprites and elves were obtained during summer 2003, in conjunction with an upgraded Duke University ELF transient monitoring system. Some initial results will be presented.

  7. Research Opportunities at Storm Peak Laboratory

    NASA Astrophysics Data System (ADS)

    Hallar, A. G.; McCubbin, I. B.

    2006-12-01

    The Desert Research Institute (DRI) operates a high elevation facility, Storm Peak Laboratory (SPL), located on the west summit of Mt. Werner in the Park Range near Steamboat Springs, Colorado at an elevation of 3210 m MSL (Borys and Wetzel, 1997). SPL provides an ideal location for long-term research on the interactions of atmospheric aerosol and gas- phase chemistry with cloud and natural radiation environments. The ridge-top location produces almost daily transition from free tropospheric to boundary layer air which occurs near midday in both summer and winter seasons. Long-term observations at SPL document the role of orographically induced mixing and convection on vertical pollutant transport and dispersion. During winter, SPL is above cloud base 25% of the time, providing a unique capability for studying aerosol-cloud interactions (Borys and Wetzel, 1997). A comprehensive set of continuous aerosol measurements was initiated at SPL in 2002. SPL includes an office-type laboratory room for computer and instrumentation setup with outside air ports and cable access to the roof deck, a cold room for precipitation and cloud rime ice sample handling and ice crystal microphotography, a 150 m2 roof deck area for outside sampling equipment, a full kitchen and two bunk rooms with sleeping space for nine persons. The laboratory is currently well equipped for aerosol and cloud measurements. Particles are sampled from an insulated, 15 cm diameter manifold within approximately 1 m of its horizontal entry point through an outside wall. The 4 m high vertical section outside the building is capped with an inverted can to exclude large particles.

  8. P2.3 DEVELOPMENT OF A COMPREHENSIVE SEVERE WEATHER FORECAST VERIFICATION SYSTEM AT THE STORM PREDICTION CENTER

    E-print Network

    P2.3 DEVELOPMENT OF A COMPREHENSIVE SEVERE WEATHER FORECAST VERIFICATION SYSTEM AT THE STORM Institute for Mesoscale Meteorological Studies, University of Oklahoma, Norman, OK 2 NOAA/NWS Storm of the Storm Prediction Center (SPC), which is responsible for issuing forecasts of severe convection over

  9. SUMMER CALENDAR Summer 2006

    E-print Network

    Su, Xiao

    SUMMER CALENDAR 2006 Summer 2006 Monday..........................June 05 Due Day for 10-Week Session ** To obtain an electronic copy of this calendar and other AY Calendars, please visit ** http://www.sjsu.edu/academic_programs/calendars/academic_calendar #12;2006 Summer 1 2 3 4

  10. Preconditioning of the Magnetosphere by Calms before the Storm

    NASA Astrophysics Data System (ADS)

    Borovsky, J. E.; Lavraud, B.; Denton, M. H.; Steinberg, J. T.

    2006-12-01

    Intervals of extreme geomagnetic calm occur just prior to 66% of all recurring high-speed-stream-driven storms and just prior to 38% of CME-driven storms. An interval of calm prior to the onset of a storm can precondition the magnetosphere, resulting in a change in the nature of the storm. We will focus on changes in the storms caused by the build up of a large plasmasphere and the build up of cool dense plasma sheet (CDPS) plasma in the magnetosphere. We argue that the built-up plasmasphere during the calm and the resulting plasmaspheric drainage plume during the storm leads to (1) mass loading of the dayside neutral line causing a reduction in solar-wind/magnetosphere coupling during the storm, (2) enhanced decay of the number density of relativistic electrons in the outer radiation belt prior to the storm, (3) a dumping of the outer electron radiation belt by the formation of a clumpy plasmaspheric drainage plume in the early phase of the storm, and (4) mass loading of convection in the inner magnetosphere. We argue that the build up of CDPS plasma in the magnetosphere during a calm provides a more efficient fuel for the production of ring current during the early phase of the storm.

  11. Evolution of vertical drafts and cloud-to-ground lightning within the convective region of a mesoscale convective complex

    E-print Network

    Saul, Scott Henry

    1995-01-01

    convective complex (MCC) was examined over a 100 minute period during the storm's mature stage and compared to that of a squall line. The area-averaged vertical velocity profiles from twenty dual-Doppler analyses indicated significant differences...

  12. Nowcasting, warning, mitigation, and documentation of hail storms in Styria, Austria

    NASA Astrophysics Data System (ADS)

    Teschl, Franz; Teschl, Reinhard; Paulitsch, Helmut; Randeu, Walter L.

    2013-04-01

    The South-East of the Austrian province of Styria is a hail-hotspot. Typically on more than 50 days in summer hail warnings are released. Since decades, hail mitigation actions are carried out by means of specially equipped aircraft seeding 'suspicious' clouds with silver-iodide generators. In the year 2009, a project was started with the goal to document hail events and to increase the efficiency of hail finding measures. Since decades, the weather situation is observed in this region by the Austrian C-band weather radar network that provides every five minutes updated 3D reflectivity and velocity measurements with a resolution of 1 km. In 2009, the aircraft used for cloud seeding have been equipped with GPS sensors and tablet PCs. As a consequence, the position of the aircraft is accessible in close to real time and can be marked in the weather radar images. Further, the aircraft pilots have access to the current weather radar images. This idea guarantees a two-way information exchange. On the one hand, the pilots get a full picture of the overall weather situation. On the other hand, it can be documented what cloud cells the experienced aircraft pilots regarded as critical and when and where they chose to seed. Since the project started, aircraft seeding has been documented on more than 150 days. This study analyzes convective storms as they were tracked with the weather radar during their life cycle - from the origin to the collapse. Both categories of cells, seeded and unseeded ones, have been analyzed. The duration, the path-length of the track over ground, the vertical profile, the zero-degree isotherm, as well as the precipitation rate have been extracted. These datasets will allow the evaluation of forecast models for convective storms. It was further evaluated if the seeded convective storms met standardized seeding criteria. A long term perspective of the ongoing project is a scientific analysis of the effects of the hail suppression measures based on the comparison of seeded and unseeded convective cells and on documented hail information from the ground.

  13. Tropical storm structure revealed by stereoscopic photographs from Skylab

    NASA Astrophysics Data System (ADS)

    Black, P. G.

    A stereo pair of photographs taken by Skylab astronauts over Hurricane Ellen, September 19, 1973, resulted in the first stereo analysis over tropical storms. This pair is also the first evidence to indicate the existence of ``supercell'' convection in developing tropical storms. The photos are analyzed to determine the cloud top structure of the intense convection occurring in one quadrant of the storm. This type of supercell convection in tropical storms has recently been correlated with subsequent rapid deepening. The stereo analysis revealed that a circular cloud feature over the storm center was a dome which protruded 3-4 km above the undisturbed cirrus clouds. The center of the dome was capped by smaller scale convective turrets which protruded another 1-2 km above the dome. The existence of shear induced waves in the cloud tops is shown with wave amplitude ranging from 150-300 m and wave lengths ranging from 2-4 km. The existence of gravity waves at the cloud tops is also shown with wave amplitudes of 500-600 m and wavelengths of 10-12 km.

  14. Detection of hazardous storms over South Africa using MSG/SEVIRI image data

    NASA Astrophysics Data System (ADS)

    Hardy, Caroline H.; Nel, André L.

    2010-10-01

    A methodology for detecting potentially hazardous storms over South Africa using meteorological satellite imagery from Meteosat Second Generation (MSG)/SEVIRI is presented. An index indicative of the hazardous potential of a storm is defined to aid in the identification of affected geographical areas and to quantify the destructive potential of the detected storm. The data from MSG/SEVIRI infrared channels is employed to analyze potentially hazardous storms. A hazardous potential index (HPI) is generated through the use of image processing techniques such as cloud masking, cloud tracking and an image-based analysis of the constituent elements of a severe convective storm.

  15. Martian dust storms as a possible sink of atmospheric methane W. M. Farrell,1

    E-print Network

    Atreya, Sushil

    that Martian dust devils and larger dusty convective storms generate and maintain large-scale electric fields electron dissociation of methane in the high E-field environments expected in Martian dust devils, larger

  16. STORM WATER Residential

    E-print Network

    California at Santa Cruz, University of

    STORM WATER QUALITY HOTLINE UCSC Residential Car Washing http THAT MAY CAUSE ENVIRONMENTAL HARM TO THE STORM WATER QUALITY HOTLINE: (831) 459-2553. LIKE US ON FACEBOOK AT UCSC STORM WATER MANAGEMENT PROGRAM! DID YOU KNOW? PRACTICAL SOLUTIONS > USE A COMMERCIAL CAR WASH

  17. Convective cell development and propagation in a mesoscale convective complex

    E-print Network

    Ahn, Yoo-Shin

    1987-01-01

    ~ , National Fisheries University of Pusan Chairman of Advisory Committee: Dr ~ Kennth CD Brundidge A case study was made of the mesoscale convective complex (MCC) which occurred over southern Oklahoma and northern Texas on 27 May 1981. This storm moved... in an east-southeasterly direction and during much of its lifetime was observable by radars at Oklahoma City, OK and Stephenville, TX. It was found that the direction of cell (VIP level 3 or more reflectivity) propagation was somewhat erratic...

  18. The relative contributions of summer and cool-season precipitation to groundwater recharge, Spring Mountains, Nevada, USA

    USGS Publications Warehouse

    Winograd, I.J.; Riggs, A.C.; Coplen, T.B.

    1998-01-01

    A comparison of the stable-isotope signatures of spring waters, snow, snowmelt, summer (July thru September) rain, and cool season (October thru June) rain indicates that the high-intensity, short-duration summer convective storms, which contribute approximately a third of the annual precipitation to the Spring Mountains, provide only a small fraction (perhaps 10%) of the recharge to this major upland in southern Nevada, USA. Late spring snowmelt is the principal means of recharging the fractured Paleozoicage carbonate rocks comprising the central and highest portion of the Spring Mountains. Daily discharge measurements at Peak Spring Canyon Creek during the period 1978-94 show that snowpacks were greatly enhanced during E1 Nin??o events.

  19. Storms in Space

    NASA Astrophysics Data System (ADS)

    Freeman, John W.

    2012-11-01

    Introduction; The cast of characters; Vignettes of the storm; 1. Two kinds of weather; 2. The saga of the storm; 3. Weather stations in space; 4. Lights in the night: the signature of the storm; 5. A walking tour of the magnetosphere; 6. The sun: where it all begins; 7. Nowcasting and forecasting storms in space; 8. Technology and the risks from storms in space; 9. A conversation with Joe Allen; 10. Manned exploration and space weather hazards; 11. The present and future of space weather forecasting; Mathematical appendix. A closer look; Glossary; Figure captions.

  20. Cloud-to-Ground Lightning throughout the Lifetime of a Severe Storm System in Oklahoma

    Microsoft Academic Search

    Mark A. Shafer; Donald R. MacGorman; Frederick H. Carr

    2000-01-01

    Cloud-to-ground (CG) lightning data are examined relative to digitized radar data for a storm system that occurred in Oklahoma on 26 May 1985. This system evolved through three stages: 1) two lines of cells, one near the dryline and the other 60 km ahead of it; 2) a supercell storm; and 3) a mesoscale convective system (MCS). The behavior of

  1. Evaluation of UAS Concepts of Operation for Severe Storm Penetration using Hardware-in-the-Loop

    E-print Network

    Frew, Eric W.

    Evaluation of UAS Concepts of Operation for Severe Storm Penetration using Hardware-in-the-Loop Houston § University of Nebraska, Lincoln, NE, 68588, USA A system developed for hardware-in-the-loop severe convective storms. Interfaces have been written to enable the use of system hardware where

  2. Application of new methods based on ECMWF ensemble model for predicting severe convective weather situations

    NASA Astrophysics Data System (ADS)

    Lazar, Dora; Ihasz, Istvan

    2013-04-01

    The short and medium range operational forecasts, warning and alarm of the severe weather are one of the most important activities of the Hungarian Meteorological Service. Our study provides comprehensive summary of newly developed methods based on ECMWF ensemble forecasts to assist successful prediction of the convective weather situations. . In the first part of the study a brief overview is given about the components of atmospheric convection, which are the atmospheric lifting force, convergence and vertical wind shear. The atmospheric instability is often used to characterize the so-called instability index; one of the most popular and often used indexes is the convective available potential energy. Heavy convective events, like intensive storms, supercells and tornadoes are needed the vertical instability, adequate moisture and vertical wind shear. As a first step statistical studies of these three parameters are based on nine years time series of 51-member ensemble forecasting model based on convective summer time period, various statistical analyses were performed. Relationship of the rate of the convective and total precipitation and above three parameters was studied by different statistical methods. Four new visualization methods were applied for supporting successful forecasts of severe weathers. Two of the four visualization methods the ensemble meteogram and the ensemble vertical profiles had been available at the beginning of our work. Both methods show probability of the meteorological parameters for the selected location. Additionally two new methods have been developed. First method provides probability map of the event exceeding predefined values, so the incident of the spatial uncertainty is well-defined. The convective weather events are characterized by the incident of space often rhapsodic occurs rather have expected the event area can be selected so that the ensemble forecasts give very good support. Another new visualization tool shows time evolution of predefined multiple thresholds in graphical form for any selected location. With applying this tool degree of the dangerous weather conditions can be well estimated. Besides intensive convective periods are clearly marked during the forecasting period. Developments were done by MAGICS++ software under UNIX operating system. The third part of the study usefulness of these tools is demonstrated in three interesting cases studies of last summer.

  3. Seasonal solute dynamics across land uses during storms in glaciated landscape of the US Midwest

    NASA Astrophysics Data System (ADS)

    Vidon, P.; Hubbard, L. E.; Soyeux, E.

    2009-09-01

    SummaryConsidering the importance of solute exports during storms in annual nutrient budgets at the watershed scale, it is critical to understand the impact of seasonality and differences in land use on watershed hydrological and biogeochemical response to storm events. This study investigates the hydrological response to storms and chloride, nitrate and dissolved organic carbon (DOC) export dynamics during one spring storm and two summer storms in an agricultural catchment (watershed A) and a mixed agricultural/urban catchment (watershed M). Drier antecedent moisture conditions in summer were associated with lower runoff ratios during summer storms than during the spring storm studied. Watershed M also had a much flashier hydrologic behavior than watershed A, suggesting that moderate differences in land use significantly affected each watershed hydrological response to storm events. DOC concentrations were not significantly different between watersheds A and M; however, nitrate and chloride concentrations and export rates were, respectively, higher and lower in watershed A than M. Regardless of land use, nitrate concentrations were also consistently higher during the spring storm than during the two summer storms studied. Although DOC concentrations varied seasonally, precipitation characteristics appeared to be the primary controls on DOC concentration during storms. Generally, chloride and DOC concentrations, respectively, decreased and increased along with discharge during storms. No clear concentration patterns relative to discharge were observed for nitrate in the agricultural watershed. Nitrate concentrations tended to increase following the peak in discharge in the mixed land use watershed. Analysis of stream DOC specific UV absorbance (SUVA) indicated a sharp increase in stream DOC aromaticity during storms regardless of land use and seasons, suggesting a shift in the source of DOC to the stream during storms from low aromaticity DOC at baseflow to highly aromatic DOC during storms. Overall, although many variables can contribute to differences in solute flushing patterns between the watersheds studied, this study indicates that moderate differences in land use (85% agriculture in the agricultural watershed, and 33% agriculture/33% urban/17% pasture/13% forest in the mixed land use watershed), storm characteristics and seasonality (spring vs. summer) can significantly impact watershed response to precipitation and patterns of chloride, nitrate and DOC exports during storms at the watershed scale. Owing to the importance of solute export dynamics in streams during storms in annual solute budgets, we argue that more studies investigating the impact of seasonality and differences in land uses on watersheds' hydrological and biogeochemical responses to storms should be conducted in a variety of geomorphic settings.

  4. Behavior of Ring Current and Radiation Belt Particles under the Observed Storm-Time Electric Fields

    Microsoft Academic Search

    Y. Nishimura; A. Shinbori; T. Ono; M. Iizima; A. Kumamoto

    2006-01-01

    In the inner magnetosphere the storm-time electric field has an important role to inject and accelerate ring current particles Although it has been considered that the enhanced convection largely contributes to the storm-time electric field the electric fields more than 5 mV m is observed in a limited L -shell range around L 3 during geomagnetic storms Wygant et al

  5. Satellite observation and mesoscale cloud modeling of St. Anthony, Minnesota storm clouds

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Tsao, Y. D.; Dodge, J. C.

    1989-01-01

    Both rawinsonde data and geosynchronous satellite imagery were used to study the life cycles of St. Anthony, Minnesota's severe convective storms. Cloud modeling, with input sounding data from Saint Cloud, Minnesota, and rapid-scan imagery from GOES were used to investigate storm cloud formation, development and dissipation. Comparisons were made among the seven groups of severe storms which produced an outbreak of 30 tornadoes across the United States.

  6. Vorticity imbalance and stability in relation to convection

    NASA Technical Reports Server (NTRS)

    Read, W. L.; Scoggins, J. R.

    1977-01-01

    A complete synoptic-scale vorticity budget was related to convection storm development in the eastern two-thirds of the United States. The 3-h sounding interval permitted a study of time changes of the vorticity budget in areas of convective storms. Results of analyses revealed significant changes in values of terms in the vorticity equation at different stages of squall line development. Average budgets for all areas of convection indicate systematic imbalance in the terms in the vorticity equation. This imbalance resulted primarily from sub-grid scale processes. Potential instability in the lower troposphere was analyzed in relation to the development of convective activity. Instability was related to areas of convection; however, instability alone was inadequate for forecast purposes. Combinations of stability and terms in the vorticity equation in the form of indices succeeded in depicting areas of convection better than any one item separately.

  7. Extreme convection of the near-equatorial Americas, Africa, and adjoining oceans as seen by TRMM

    E-print Network

    Houze Jr., Robert A.

    1 Extreme convection of the near-equatorial Americas, Africa, and adjoining oceans as seen by TRMM;2 Abstract This study documents the preferred location and diurnal cycle of extreme convective storms Ocean, and Northern Africa. Data from the TRMM Precipitation Radar show three types of convective

  8. The Storm-Substorm Relationship during Different Solar Wind Conditions

    NASA Astrophysics Data System (ADS)

    Hsu, T. S.; McPherron, R. L.; Chu, X.

    2014-12-01

    Solar-terrestrial coupling is the study of processes which transfer solar wind energy to the magnetosphere creating geomagnetic activity. This coupling depends on properties of the solar wind and particularly on the discrete structures present in the solar wind. These include CMEs, CIRs, and HSS (high speed streams) which have very different characteristics causing different modes of response of the magnetosphere such as magnetic storm, substorms, steady magnetospheric convection (SMC) and others. Among these different modes of response, magnetic storms and substorms are two of the primary ones because they occur frequently and because they can cause considerable problems in technological systems. The differences in solar wind driving conditions during CME, CIR, and HSS provide a good opportunity to examine how the properties of substorms change with solar wind structures and the activity they create. Since the probability of observing these structures is a function of solar cycle phase, the storm-substorm relationship changes with solar cycle phase. It is possible that the nature of solar wind coupling changes with the type of storm, storm intensity, and/or the phase of the storms. The original hypothesis was that a magnetic storm is simply a superposition of substorms. However, some evidences have been found that storms begin to develop before substorms occur. Is substorm occurrence independent of storm development? This would suggest that substorms can be seen in any phase of a storm and even a storm without substorms. There are some recent studies suggest this is possible. However, most of the studies did not take into consideration different solar wind driving conditions. In this study, we will investigate several aspects of the relation of substorms to storms such as: Does the frequency and intensity of substorms change with phase of the solar cycle? Are there differences in these properties between cycles? Are the characteristics of substorms different if they occur within a storm or outside of a storm? Are CME storm time substorms different from CIR storm substorms? Do substorm properties change with phase of the storm?

  9. Spatial analysis of storm depths from an Arizona raingage network

    NASA Technical Reports Server (NTRS)

    Fennessey, N. M.; Eagleson, P. S.; Qinliang, W.; Rodriguez-Iturbe, I.

    1986-01-01

    Eight years of summer rainstorm observations are analyzed by a dense network of 93 raingages operated by the U.S. Department of Agriculture, Agricultural Research Service, in the 150 km Walnut Gulch experimental catchment near Tucson, Arizona. Storms are defined by the total depths collected at each raingage during the noon-to-noon period for which there was depth recorded at any of the gages. For each of the resulting 428 storm days, the gage depths are interpolated onto a dense grid and the resulting random field analyzed to obtain moments, isohyetal plots, spatial correlation function, variance function, and the spatial distribution of storm depth.

  10. Large Eddy Simulations of Severe Convection Induced Turbulence

    NASA Technical Reports Server (NTRS)

    Ahmad, Nash'at; Proctor, Fred

    2011-01-01

    Convective storms can pose a serious risk to aviation operations since they are often accompanied by turbulence, heavy rain, hail, icing, lightning, strong winds, and poor visibility. They can cause major delays in air traffic due to the re-routing of flights, and by disrupting operations at the airports in the vicinity of the storm system. In this study, the Terminal Area Simulation System is used to simulate five different convective events ranging from a mesoscale convective complex to isolated storms. The occurrence of convection induced turbulence is analyzed from these simulations. The validation of model results with the radar data and other observations is reported and an aircraft-centric turbulence hazard metric calculated for each case is discussed. The turbulence analysis showed that large pockets of significant turbulence hazard can be found in regions of low radar reflectivity. Moderate and severe turbulence was often found in building cumulus turrets and overshooting tops.

  11. Urban Heat Islands and Summertime Convective Thunderstorms in Atlanta: Three Case Studies

    NASA Technical Reports Server (NTRS)

    Bornstein, Robert; Lin, Qinglu; Goodman, H. Michael (Technical Monitor)

    1999-01-01

    Data from both 27 sites in the Atlanta mesonet surface meteorological network and eight National Weather Service sites were analyzed for the period from 26 July to 3 August 1996. Analysis of the six precipitation events over the city during the period (each on a different day) showed that its urban heat island (UHI) induced a convergence zone that initiated three of the storms at different times of the day, i.e., 0630,0845, and 1445 EDT. Previous analysis has shown that New York City (NYC) effects summer daytime thunderstorm formation and/or movement. That study found that during nearly calm regional flow conditions the NYC UHI initiates convective activity. Moving thunderstorms, however, tended to bifurcate and to move around the city, due to its building barrier effect. The current Atlanta results thus agree with the NYC results with respect to thunderstorm initiation.

  12. Modeling Convection

    NSDL National Science Digital Library

    Amanda Schulz

    2004-09-01

    Typically, teachers use simple models that employ differences in temperature and density to help students visualize convection. However, most of these models are incomplete or merely hint at (instead of model) convective circulation. In order to make the use of models more effective, the authors developed an alternative system that uses a simple, low-cost apparatus that not only maintains dynamic convective circulation, but also illustrates two adjacent cells that teaches students about Earth's processes.

  13. Tropical Storms, Worldwide

    NSDL National Science Digital Library

    The University of Hawaii's Mees Solar Observatory, stationed at Haleakala, Maui, provides a wealth of data and images in its Webpages. This page, Tropical Storms Worldwide, gives regional maps and written updates of hurricane, typhoon, and tropical cyclone activity around the globe. The page also features a strike probability calculator where users click on a list of geographic locations or enter map coordinates or a US zip code in order to view the probability of a tropical storm reaching that area. A storm data archive (1994-2000) and printer-friendly .pdf-formatted storm track maps are also available.

  14. Convective initiation in the vicinity of the subtropical Andes

    NASA Astrophysics Data System (ADS)

    Rasmussen, K. L.; Houze, R.

    2014-12-01

    Extreme convection tends to form in the vicinity of mountain ranges, and the Andes in subtropical South America help spawn some of the most intense convection in the world. An investigation of the most intense storms for 11 years of TRMM Precipitation Radar (PR) data shows a tendency for squall lines to initiate and develop in this region with the canonical leading convective line/trailing stratiform structure. The synoptic environment and structures of the extreme convection and MCSs in subtropical South America are similar to those found in other regions of the world, especially the United States. In subtropical South America, however, the topographical influence on the convective initiation and maintenance of the MCSs is unique. A capping inversion in the lee of the Andes is important in preventing premature triggering. The Andes and other mountainous terrain of Argentina focus deep convective initiation in a narrow region. Subsequent to initiation, the convection often evolves into propagating mesoscale convective systems similar to those seen over the Great Plains of the U. S. and produces damaging tornadoes, hail, and floods across a wide agricultural region. Numerical simulations conducted with the NCAR Weather Research and Forecasting (WRF) Model extend the observational analysis and provide an objective evaluation of storm initiation, terrain effects, and development mechanisms. The simulated mesoscale systems closely resemble the storm structures seen by the TRMM Precipitation Radar as well as the overall shape and character of the storms shown in GOES satellite data. A sensitivity experiment with different configurations of topography, including both decreasing and increasing the height of the Andes Mountains, provides insight into the significant influence of orography in focusing convective initiation in this region. Lee cyclogenesis and a strong low-level jet are modulated by the height of the Andes Mountains and directly affect the character, intensity, and spatial distribution of the convective systems. A new conceptual model for convective initiation in subtropical South America that integrates the results of the topographic sensitivity experiments will be presented.

  15. A source for the geomagnetic storm main phase ring current

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.; Williams, D. J.

    1980-01-01

    The paper considers a proposed source for the geomagnetic storm main phase ring current. It is shown that the flux increases of trapped ions and electrons observed by Explorer 45 at L below 4 during two large geomagnetic storms can be explained by inward radial displacement of the preexisting trapped particle distribution. The proposed source requires only the acceleration of the previously entrapped particle population by inward displacement under conservation of the first two adiabatic invariants. It is suggested that a significant difference between large geomagnetic storms and typical substorm activity may be the inward convection occurring over a large longitude range during storms, but only over a small longitude range during typical substorms.

  16. Validation of storm surge

    E-print Network

    Vries, Hans de

    G G G G Validation of storm surge forecasts for the Dutch coast Hans de Vries KNMI, Weather Service Research and Development Hans.de.Vries@knmi.nl G G G G Coastal Model Validation Storm surge forecasts for the Dutch coast 18 20 Nov 2009 1 #12;G G G G Overview GLAMEPS Harmonie G G G G Coastal Model Validation

  17. On Typhoon storm tides

    Microsoft Academic Search

    H. Arakawa

    1957-01-01

    Summary After reviewing current theories on synoptic types producing coastal inundations, the author proposed a theory on the dynamics of catastrophic typhoon tides after resonance and hydraulic analogy. As examples, case studies of the storm tides caused by the Muroto Typhoon of 1934 and the 1917 Typhoon are given. Another type of the storm tide caused by the crossing of

  18. Structure of Highly Sheared Tropical Storm Chantal during CAMEX-4

    NASA Technical Reports Server (NTRS)

    Heymsfield, G. M.; Halverson, J.; Ritchie, E.; Simpson, Joanne; Molinari, J.; Tian, L.

    2006-01-01

    Tropical Storm Chantal during August 2001 was a storm that failed to intensify over the few days prior to making landfall on the Yucatan Peninsula. An observational study of Tropical Storm Chantal is presented using a diverse dataset including remote and in situ measurements from the NASA ER-2 and DC-8 and the NOAA WP-3D N42RF aircraft and satellite. The authors discuss the storm structure from the larger-scale environment down to the convective scale. Large vertical shear (850-200-hPa shear magnitude range 8-15 m/s) plays a very important role in preventing Chantal from intensifying. The storm had a poorly defined vortex that only extended up to 5-6-km altitude, and an adjacent intense convective region that comprised a mesoscale convective system (MCS). The entire low-level circulation center was in the rain-free western side of the storm, about 80 km to the west-southwest of the MCS. The MCS appears to have been primarily the result of intense convergence between large-scale, low-level easterly flow with embedded downdrafts, and the cyclonic vortex flow. The individual cells in the MCS such as cell 2 during the period of the observations were extremely intense, with reflectivity core diameters of 10 km and peak updrafts exceeding 20 m/s. Associated with this MCS were two broad subsidence (warm) regions, both of which had portions over the vortex. The first layer near 700 hPa was directly above the vortex and covered most of it. The second layer near 500 hPa was along the forward and right flanks of cell 2 and undercut the anvil divergence region above. There was not much resemblance of these subsidence layers to typical upper-level warm cores in hurricanes that are necessary to support strong surface winds and a low central pressure. The observations are compared to previous studies of weakly sheared storms and modeling studies of shear effects and intensification. The configuration of the convective updrafts, low-level circulation, and lack of vertical coherence between the upper- and lower-level warming regions likely inhibited intensification of Chantal. This configuration is consistent with modeled vortices in sheared environments, which suggest the strongest convection and rain in the downshear left quadrant of the storm, and subsidence in the upshear right quadrant. The vertical shear profile is, however, different from what was assumed in previous modeling in that the winds are strongest in the lowest levels and the deep tropospheric vertical shear is on the order of 10-12 m/s.

  19. Ionospheric storms—A challenge for empirical forecast of the total electron content

    NASA Astrophysics Data System (ADS)

    Borries, C.; Berdermann, J.; Jakowski, N.; Wilken, V.

    2015-04-01

    Since the last decades, the functioning of society depends more and more on well-functioning communication and navigation systems. As the availability and reliability of most of these satellite-based systems can be severely impacted by ionospheric storms, the accurate forecast of these events becomes a required task for mitigating social and economic risks. Here we aim to make initial steps toward an empirical model for ionospheric perturbations related to space weather events that are observable in the total electron content (TEC). The perturbation TEC forecast model will be a fast and robust approach, improving TEC forecasts based on climatological models during storm conditions. The derivation of such a model is a challenging task, because although a general dependence of the storm features (enhancement or depletion of electron density) on the storm onset time, local time, season and geomagnetic latitude is well known, there is a large deviation from the mean behavior. For a better understanding of storm conditions, this paper presents analyses of ionospheric storms observed in the TEC, broken down into diverse classes of storms. It provides a detailed characterization of the typical ionospheric storm behavior over Europe from high to midlatitudes, beyond case studies. Generally, the typical clear strong TEC enhancement starting in high latitudes and propagating equatorward is found to be strongest for storms starting in the morning hours independent of the season. In midlatitudes, it is strongest during noon. In addition, a clear difference between summer and winter storms is reported. While only winter storms develop high-latitude TEC enhancements, only summer storms typically exhibit TEC depletions during the storm recovery phase. During winter storms TEC enhancements can also occur the day following the storm onset, in contrast to summer storms. Strong correlation of TEC perturbation amplitudes to the Bz component of the interplanetary magnetic field and to a proxy of the polar cap potential are shown especially for summer midlatitude TEC enhancements during storms with and onset in the morning hours (6 to 12 UT over Europe) and for winter high-latitude TEC enhancements (around 60?N). The results indicate the potential to derive improved predictions of maximum TEC deviations during space weather events, based on solar wind measurements.

  20. Purification function of riverbank plants to infiltrated polluted storm runoff

    Microsoft Academic Search

    Yu Dai; Yong Jiang; Cheng Yao; Chao Xue

    2011-01-01

    A systematic pot test was performed both in summer and autumn, which the purification efficiency to the polluted urban storm runoff was studied. The orthogonal method was applied to design the experiment. 24 plastic pots were divided into eight groups, and each group included a blank sample and two parallel samples for comparison. The results showed that: (1) the removal

  1. F layer positive response to a geomagnetic storm - June 1972

    NASA Technical Reports Server (NTRS)

    Miller, N. J.; Grebowsky, J. M.; Mayr, H. G.; Harris, I.; Tulunay, Y. K.

    1979-01-01

    A circulation model of neutral thermosphere-ionosphere coupling is used to interpret in situ spacecraft measurements taken during a topside midlatitude ionospheric storm. The data are measurements of electron density taken along the circular polar orbit of Ariel 4 at 550 km during the geomagnetically disturbed period June 17-18, 1972. It is inferred that collisional momentum transfer from the disturbed neutral thermosphere to the ionosphere was the dominant midday process generating the positive F-layer storm phase in the summer hemisphere. In the winter hemisphere the positive storm phase drifted poleward in the apparent response to magnetospheric E x B drifts. A summer F-layer positive phase developed at the sudden commencement and again during the geomagnetic main phase; a winter F-layer positive phase developed only during the geomagnetic main phase. The observed seasonal differences in both the onsets and the magnitudes of the positive phases are attributed to the interhemispheric asymmetry in thermospheric dynamics.

  2. New insights on geomagnetic storms from observations and modeling

    SciTech Connect

    Jordanova, Vania K [Los Alamos National Laboratory

    2009-01-01

    Understanding the response at Earth of the Sun's varying energy output and forecasting geomagnetic activity is of central interest to space science, since intense geomagnetic storms may cause severe damages on technological systems and affect communications. Episodes of southward (Bzstorms representative of each interplanetary condition with our kinetic ring current atmosphere interactions model (RAM), and investigate the mechanisms responsible for trapping particles and for causing their loss. We find that periods of increased magnetospheric convection coinciding with enhancements of plasma sheet density are needed for strong ring current buildup. During the HSS-driven storm the convection potential is highly variable and causes small sporadic injections into the ring current. The long period of enhanced convection during the CME-driven storm causes a continuous ring current injection penetrating to lower L shells and stronger ring current buildup.

  3. Equatorial Thermospheric Responses to Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Earle, G. D.; Davidson, R.; Heelis, R. A.; Coley, W. R.; Weimer, D. R.; Makela, J. J.; Fisher, D. J.

    2012-12-01

    Low latitude observations by the C/NOFS-CINDI satellite mission reveal marked neutral density enhancements commencing a few hours after the onset of geomagnetic storms. These perturbations are consistent with increases in atmospheric scale heights driven by thermospheric heating at altitudes below the C/NOFS observation height. The time lags between storm onsets and observed scale height increases near the equator are consistent with propagation times for traveling ionospheric disturbances (TIDs) from high to low latitudes. We examine several storms from fall 2011 and spring/summer 2012 and compare the gross features of thermospheric heating and perturbation winds that arise in each case. On average we find the density perturbations near 400 km altitude to be about 50% of the background, with perturbation winds near 150 m/s in the equatorward direction. These observations are in good agreement with empirical model predictions based on the CHAMP and GRACE missions. Simultaneous ground-based observations at lower altitudes are found to compare favorably to the in-situ measurements during storm periods.

  4. Dust storms: recent developments.

    PubMed

    Goudie, Andrew S

    2009-01-01

    Dust storms have a number of impacts upon the environment including radiative forcing, and biogeochemical cycling. They transport material over many thousands of kilometres. They also have a range of impacts on humans, not least on human health. In recent years the identification of source areas for dust storms has been an important area or research, with the Sahara (especially Bodélé) and western China being recognised as the strongest sources globally. Another major development has been the recognition of the degree to which dust storm activity has varied at a range of time scales, millennial, century, decadal, annual and seasonal. PMID:18783869

  5. Dusty gust fronts and their contributions to long-lived convection in West Africa/

    E-print Network

    McGraw-Herdeg, Michael (Michael P.)

    2010-01-01

    To model and predict the behavior of West African storms and mesoscale convective systems (MCSs), we must understand the life cycle of gust fronts, which invariably accompany thunderstorms and often initiate them. In this ...

  6. Ionospheric storm time dynamics as seen by GPS tomography and in situ spacecraft observations

    NASA Astrophysics Data System (ADS)

    Pokhotelov, D.; Mitchell, C. N.; Spencer, P. S. J.; Hairston, M. R.; Heelis, R. A.

    2008-03-01

    During major geomagnetic storms anomalous enhancements of the ionospheric density are seen at high and middle latitudes. A number of physical mechanisms have been invoked to explain these storm time density anomalies including an expansion of high-latitude electric plasma convection to midlatitudes, thermospheric neutral winds, and changes in the ionospheric composition. However, it remains unclear which mechanism plays the dominant role in the formation of storm time density anomalies, partly because of insufficient coverage of the measurements of global electric convection and thermospheric winds at midlatitudes. This paper describes a novel technique for extracting the storm time E × B convection boundary from in situ measurements of plasma bulk motion obtained by LEO DMSP satellites. The convection boundary estimated from the DMSP data during major magnetic storm of 20 November 2003 has been compared with the global distributions of the ionospheric plasma deduced from characteristics of GPS signals acquired by a ground-based network of GPS receivers. The tomographic inversion of GPS data using a three-dimensional time-dependent inversion technique reveals the spatial and temporal evolution of the storm time density anomaly. Comparison between the tomographic reconstructions of the ionospheric plasma distributions and in situ DMSP measurements of plasma bulk motion suggests that the convective flow expanded low enough in latitude to encompass, in part, the formation of the midlatitude TEC anomaly. Some features of the TEC dynamics observed during the 20 November 2003 storm, however, suggest that mechanisms other than the expanded ionospheric convection (such as thermospheric neutral winds) are also involved in the formation of the midlatitude anomaly.

  7. Observation and numerical simulation of a convective initiation during COHMEX

    NASA Technical Reports Server (NTRS)

    Song, J. Aaron; Kaplan, Michael L.

    1991-01-01

    Under a synoptically undisturbed condition, a dual-peak convective lifecycle was observed with the COoperative Huntsville Meteorological EXperiment (COHMEX) observational network over a 24-hour period. The lifecycle included a multicell storm, which lasted about 6 hours, produced a peak rainrate exceeding 100 mm/hr, and initiated a downstream mesoscale convective system. The 24-hour accumulated rainfall of this event was the largest during the entire COHMEX. The downstream mesoscale convective system, unfortunately, was difficult to investigate quantitatively due to the lack of mesoscale observations. The dataset collected near the time of the multicell storm evolution, including its initiation, was one of the best datasets of COHMEX. In this study, the initiation of this multicell storm is chosen as the target of the numerical simulations.

  8. Why do Tornados and Hail Storms Rest on Weekends?

    NASA Technical Reports Server (NTRS)

    Rosenfeld, Daniel; Bell, Thomas L.

    2010-01-01

    When anthropogenic aerosols over the eastern USA during summertime are at their weekly mid-week peak, tornado and hail storm activity there is also near its weekly maximum. The weekly cycle in storm activity is statistically significant and unlikely to be due to natural variability. The pattern of variability supports the hypothesis that air pollution aerosols invigorate deep convective clouds in a moist, unstable atmosphere, to the extent of inducing production of large hailstones and tornados. This is caused by the effect of aerosols on cloud-drop nucleation, making cloud drops smaller, delaying precipitation-forming processes and their evaporation, and hence affecting cloud dynamics.

  9. COASTAL EROSION ALONG THE CHUKCHI COAST DUE TO AN EXTREME STORM EVENT AT BARROW, ALASKA

    Microsoft Academic Search

    P. M. Sturtevant; L. R. Lestak; W. F. Manley; J. A. Maslanik

    Along the north slope of Alaska, shorefast ice protects the coast up to 9 months of the year and negligible tides and waves minimally disturb the shore during the remaining summer months. Most of the coastline change, then, is thought to occur during summer and autumn storm conditions, where heightened sea levels and increased wave action accelerate movement of coastal

  10. After the Wind Storm 

    E-print Network

    Unknown

    2011-09-05

    environments. A climatology of storm types, based on dynamical forcing (i.e., weak forcing, drylines, cold fronts, warm fronts, stationary fronts and upper level disturbances) and precipitation structure (i.e., isolated, scattered, widespread, linear...

  11. Thyrotoxicosis and thyroid storm.

    PubMed

    Nayak, Bindu; Burman, Kenneth

    2006-12-01

    Thyroid storm represents the extreme manifestation of thyrotoxicosis as a true endocrine emergency. Although Grave's disease is the most common underlying disorder in thyroid storm, there is usually a precipitating event or condition that transform the patient into life-threatening thyrotoxicosis. Treatment of thyroid storm involves decreasing new hormone synthesis, inhibiting the release of thyroid hormone, and blocking the peripheral effects of thyroid hormone. This multidrug, therapeutic approach uses thionamides, iodine, beta-adrenergic receptor antagonists, corticosteroids in certain circumstances, and supportive therapy. Certain conditions may warrant the use of alternative therapy with cholestyramine, lithium carbonate, or potassium perchlorate. After the critical illness of thyroid storm subsides, definitive treatment of the underlying thyrotoxicosis can be planned. PMID:17127140

  12. Dust Storm Safety

    MedlinePLUS

    ... stop on the traveled portion of the roadway. LIGHTS OUT! In the past, motorists driving in dust storms have pulled off the roadway, leaving lights on. Vehicles approaching from the rear and using ...

  13. Numerical simulation on the evolution of cloud particles in 3-D convective cloud

    Microsoft Academic Search

    XiaoLi Liu; ShengJie Niu

    2009-01-01

    A 3-D convective cloud model with compressible non-hydrostatic dynamics and the spectral bin microphysics of a 2-D slab-symmetric\\u000a model has been used to simulate an observed supercell storm occurring on 29 June, 2000 near Bird City, Kansas, USA. The main\\u000a objective of this paper is to study the evolution of particles in this convective storm with bin spectral microphysics scheme.

  14. Dust storm in Sudan

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A dust storm is carrying dust from Sudan, Africa, out over the Red Sea (right) in this Moderate Resolution Imaging Spectroradiometer Image from June 30, 2002. In the lower left quadrant of the image, the sinuous path of the Nile can be seen. Dust storms such as this reduce the amount of solar radiation that reaches the surface, and have a cooling effect on the area. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  15. Predicting lightning storms

    NASA Astrophysics Data System (ADS)

    Wainger, Lisa A.

    Lightning is the second most deadly weather phenomenon after flash floods. It kills more people a year than tornadoes and damages utilities, curtails recreational activities, and affects flight paths. Roughly half of all aviation accidents are weather related according to Delain Edman, of the National Weather Service's National Severe Storms Forecast Center, Kansas City, Mo. That's why meteorologists are testing a new lightning detection network to help predict storms and pinpoint “hot spots” of lightning activity.

  16. The moisture budget in relation to convection

    NASA Technical Reports Server (NTRS)

    Scott, R. W.; Scoggins, J. R.

    1977-01-01

    An evaluation of the moisture budget in the environment of convective storms is presented by using the unique 3- to 6-h rawinsonde data. Net horizontal and vertical boundary fluxes accounted for most of the large amounts of moisture which were concentrated into convective regions associated with two squall lines that moved through the area during the experiment. The largest values of moisture accumulations were located slightly downwind of the most intense convective activity. Relationships between computed moisture quantities of the moisture budget and radar-observed convection improved when lagging the radar data by 3 h. The residual of moisture which represents all sources and sinks of moisture in the budget equation was largely accounted for by measurements of precipitation.

  17. SUMMER 2011 1 SUMMER 2011

    E-print Network

    Vermont, University of

    . Keywords: Undergraduate engineering education, civil engineering, environmental engineering, systems is for our civil and environmental engineering (CEE) students to learn and apply a systems approachSUMMER 2011 1 SUMMER 2011 Advances in Engineering Education Incorporating a Systems Approach

  18. Ionospheric response to the corotating interaction region-driven geomagnetic storm of October 2002

    NASA Astrophysics Data System (ADS)

    Pokhotelov, D.; Mitchell, C. N.; Jayachandran, P. T.; MacDougall, J. W.; Denton, M. H.

    2009-12-01

    Unlike the geomagnetic storms produced by coronal mass ejections (CMEs), the storms generated by corotating interaction regions (CIRs) are not manifested by dramatic enhancements of the ring current. The CIR-driven storms are however capable of producing other phenomena typical for the magnetic storms such as relativistic particle acceleration, enhanced magnetospheric convection and ionospheric heating. This paper examines ionospheric plasma anomalies produced by a CIR-driven storm in the middle- and high-latitude ionosphere with a specific focus on the polar cap region. The moderate magnetic storm which took place on 14-17 October 2002 has been used as an example of the CIR-driven event. Four-dimensional tomographic reconstructions of the ionospheric plasma density using measurements of the total electron content along ray paths of GPS signals allow us to reveal the large-scale structure of storm-induced ionospheric anomalies. The tomographic reconstructions are compared with the data obtained by digital ionosonde located at Eureka station near the geomagnetic north pole. The morphology and dynamics of the observed ionospheric anomalies is compared qualitatively to the ionospheric anomalies produced by major CME-driven storms. It is demonstrated that the CIR-driven storm of October 2002 was able to produce ionospheric anomalies comparable to those produced by CME-driven storms of much greater Dst magnitude. This study represents an important step in linking the tomographic GPS reconstructions with the data from ground-based network of digital ionosondes.

  19. Into the Eye of the Storm

    NASA Technical Reports Server (NTRS)

    2000-01-01

    MISR acquired this stereoimage of Hurricane Alberto on August 19, 2000 during Terra orbit 3571. At this time, the storm was located in the North Atlantic Ocean, about 1700 kilometers west of the Azores. According to the National Weather Service, Alberto was increasing in intensity and exhibiting maximum sustained winds of about 165 kilometers per hour.

    This stereo 'anaglyph' image was generated using MISR's vertical (nadir)camera plus the 26-degree forward-viewing camera. It is oriented so that the spacecraft's flight path is from left to right. North is at the left. To view the image in 3-D, use red/blue glasses with the red filter over your left eye.

    Near the center of the storm, the 'eye' measures about 60 kilometers in diameter. The steep eye wall, where surface winds reach their peak intensity, is very apparent. Convective thunderclouds are present in the storm's spiral arms, and their three-dimensional structure is visible in this stereo view.

    MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

    For more information: http://www-misr.jpl.nasa.gov

  20. Convection in a Differentially Heated Narrow Slot By Teja Muppirala

    E-print Network

    Zakharov, Vladimir

    1 Convection in a Differentially Heated Narrow Slot By Teja Muppirala Advisor: Dr. Cho Lik Chan University of Arizona, Spring/Summer 2002 #12;2 Convection in a differentially heated narrow slot of fluid, and the properties of the slot. The basic principle is that fluid near the hot wall will rise due to density changes

  1. Severe convective environments in Reanalyses

    NASA Astrophysics Data System (ADS)

    Gutierrez, G.; Kennedy, A. D.

    2014-12-01

    Climate change implies an altering of weather patterns that may change the frequency of high impact events such as severe thunderstorms and their associated dangers (damaging winds, torrential rains, hail, and tornadoes). Presently, very little is known about how climate change will impact these events. Since these phenomenon are not resolved by climate models, proxies are required to understand how these events may change in the future.Prior to investigating how convective environments change in the future, a reference must be obtained to understand the current climatology of convective environments. Studies such as Kennedy et al. (2011) have shown there are significant differences in reanalyses for regions prone to severe weather.Severe weather parameters such as Convective Available Potential Energy (CAPE), Lifted Index, K Index, Total Totals, 0-1 km shear, 0-3 km shear and 0-6 km shear are calculated using soundings from reanalyses for known severe convective environments. Reanalyses included in this study are the North American Regional Reanalysis (NARR), Modern-Era Retrospective Analysis for Research and Applications (MERRA), 20th Century Reanalysis (20CR), Climate Forecast System Reanalysis (CFSR), Japanese 25-year Reanalysis (JRA25), and Japanese 55-year Reanalysis (JRA55). Preliminary findings are presented. If time allows, multi-parameter indices such as Energy Helicity Index, Bunkers storm motion, Significant Tornado Parameter, and Supercell Composite Parameter will also be compared.

  2. The Diagnosis and application of a convective vorticity vector associated with convective systems

    NASA Astrophysics Data System (ADS)

    Gao, S.; Zhou, Y.; Tao, W.

    2005-05-01

    Although dry/moist potential vorticity is a very useful and powerful physical quantity in the large scale dynamics, it is not a quite ideal dynamical tool for the study of convective systems or severe storms. A new convective vorticity vector (CVV) is introduced in this study to identify the development of convective systems or severe storms. The daily Aviation (AVN) Model Data is used to diagnose the distribution of the CVV associated with rain storms occurred in the period of Meiyu in 1998. The results have clearly demonstrated that the CVV is an effective vector for indicating the convective actions along the Meiyu front. The CVV also is used to diagnose a 2-D cloud-resolving simulation data associated with 2-D tropical convection. The cloud model is forced by the vertical velocity, zonal wind, horizontal advection, and sea surface temperature obtained from the Tropical cean-Global tmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE) and is integrated for a selected 10-day period. The CVV has zonal and vertical components in the 2-D x-z frame. Analysis of zonally averaged and mass-integrated quantities shows that the correlation coefficient between the vertical component of the CVV and the sum of the cloud hydrometeor mixing ratios is 0.81, whereas the correlation coefficient between the zonal component and the sum of the mixing ratios is only 0.18. This indicates that the vertical component of the CVV is closely associated with tropical convection. The tendency equation for the vertical component of the CVV is derived and the zonally averaged and mass-integrated tendency budgets are analyzed. The tendency of the vertical component of the CVV is determined by the interaction between the vorticity and the zonal gradient of cloud heating. The results demonstrate that the vertical component of the CVV is a cloud-linked parameter and can be used to study tropical convection.

  3. On extreme geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Cid, Consuelo; Palacios, Judith; Saiz, Elena; Guerrero, Antonio; Cerrato, Yolanda

    2014-10-01

    Extreme geomagnetic storms are considered as one of the major natural hazards for technology-dependent society. Geomagnetic field disturbances can disrupt the operation of critical infrastructures relying on space-based assets, and can also result in terrestrial effects, such as the Quebec electrical disruption in 1989. Forecasting potential hazards is a matter of high priority, but considering large flares as the only criterion for early-warning systems has demonstrated to release a large amount of false alarms and misses. Moreover, the quantification of the severity of the geomagnetic disturbance at the terrestrial surface using indices as Dst cannot be considered as the best approach to give account of the damage in utilities. High temporal resolution local indices come out as a possible solution to this issue, as disturbances recorded at the terrestrial surface differ largely both in latitude and longitude. The recovery phase of extreme storms presents also some peculiar features which make it different from other less intense storms. This paper goes through all these issues related to extreme storms by analysing a few events, highlighting the March 1989 storm, related to the Quebec blackout, and the October 2003 event, when several transformers burnt out in South Africa.

  4. DE 2 observations of disturbances in the upper atmosphere during a geomagnetic storm

    NASA Technical Reports Server (NTRS)

    Miller, N. J.; Brace, L. H.; Spencer, N. W.; Carignan, G. R.

    1990-01-01

    Results are presented of physical interpretations of a sequence of in situ measurements taken in the midlatitude dusk sector during the geomagnetic storm of November 24, 1982 by instruments on board the DE-2 spacecraft in polar orbit. The results represent the first comparison of nearly simultaneous measurements, obtained at different seasons in a common local time sector, of storm disturbances in dc electric fields, zonal ion convection, zonal winds, gas composition and temperature, and electron density and temperature.

  5. MAMS data for the Convection and Moisture Experiment (CAMEX)

    NASA Technical Reports Server (NTRS)

    Guillory, A. R.; Jedlovec, G. J.; Atkinson, R. J.

    1994-01-01

    During the fall of 1993, NASA sponsored a field program called the Convection And Moisture Experiment (CAMEX). The field effort focused on: convective storms in order to investigate their associated electrical properties, precipitation, and predictability, and atmospheric moisture studies. The data collected from the Multispectral Atmospheric Mapping Sensor (MAMS) onboard a NASA ER-2 aircraft which was deployed out of NASA/Wallops Flight Facility, Wallops Island, Virginia, from 11 Sep. through 7 Oct., 1993, is described.

  6. Vorticity imbalance and stability in relation to convection 

    E-print Network

    Read, William Light

    1976-01-01

    to convective storm development in the eastern two-thirds of the United States during NASA's fourth Atmospheric Variability Experi- ment (AVE IV). The 3-h sounding interval permitted a study of time changes of the vorticity budget in areas of convective... h. ~dt h'1' c. Thunderstorm Potential Indices 62 73 7. SUMMARY AND CONCLUSIONS REFERENCES 96 APPENDIX A 100 APPENDIX B 105 VITA 112 LIST OF FIGURES Figure Page Location of rawinsonde stations for AVE IV Locations of surface stations...

  7. A portable CW/FM-CW Doppler radar for local investigation of severe storms

    SciTech Connect

    Unruh, W.P.; Wolf, M.A.; Bluestein, H.B.

    1988-01-01

    During the 1987 spring storm season we used a portable 1-W X-band CW Doppler radar to probe a tornado, a funnel cloud, and a wall cloud in Oklahoma and Texas. This same device was used during the spring storm season in 1988 to probe a wall cloud in Texas. The radar was battery powered and highly portable, and thus convenient to deploy from our chase vehicle. The device separated the receding and approaching Doppler velocities in real time and, while the radar was being used, it allowed convenient stereo data recording for later spectral analysis and operator monitoring of the Doppler signals in stereo headphones. This aural monitoring, coupled with the ease with which an operator can be trained to recognize the nature of the signals heard, made the radar very easy to operate reliably and significantly enhanced the quality of the data being recorded. At the end of the 1988 spring season, the radar was modified to include FM-CW ranging and processing. These modifications were based on a unique combination of video recording and FM chirp generation, which incorporated a video camera and recorder as an integral part of the radar. After modification, the radar retains its convenient portability and the operational advantage of being able to listen to the Doppler signals directly. The original mechanical design was unaffected by these additions. During the summer of 1988, this modified device was used at the Langmuir Laboratory at Socorro, New Mexico in an attempt to measure vertical convective flow in a thunderstorm. 2 refs., 2 figs.

  8. A portable CW/FM-CW Doppler radar for local investigation of severe storms

    NASA Astrophysics Data System (ADS)

    Unruh, Wesley P.; Wolf, Michael A.; Bluestein, Howard B.

    During the 1987 spring storm season we used a portable 1-W X-band CW Doppler radar to probe a tornado, a funnel cloud, and a wall cloud in Oklahoma and Texas. This same device was used during the spring storm season in 1988 to probe a wall cloud in Texas. The radar was battery powered and highly portable, and thus convenient to deploy from our chase vehicle. The device separated the receding and approaching Doppler velocities in real time and, while the radar was being used, it allowed convenient stereo data recording for later spectral analysis and operator monitoring of the Doppler signals in stereo headphones. This aural monitoring, coupled with the ease with which an operator can be trained to recognize the nature of the signals heard, made the radar very easy to operate reliably and significantly enhanced the quality of the data being recorded. At the end of the 1988 spring season, the radar was modified to include FM-CW ranging and processing. These modifications were based on a unique combination of video recording and FM chirp generation, which incorporated a video camera and recorder as an integral part of the radar. After modification, the radar retains its convenient portability and the operational advantage of being able to listen to the Doppler signals directly. The original mechanical design was unaffected by these additions. During the summer of 1988, this modified device was used at the Langmuir Laboratory at Socorro, New Mexico in an attempt to measure vertical convective flow in a thunderstorm.

  9. Magnetospheric Convection near a Drainage Plume

    Microsoft Academic Search

    Chin S. Lin; Huey-Ching Yeh; Bill R. Sandel; J. Goldstein; Frederick J. Rich; William J. Burke; J. C. Foster

    2007-01-01

    We report on equatorial convection associated with a plasmaspheric drainage plume using simultaneous observations from five satellites. During the early recovery phase of the July 2000 Bastille Day magnetic storm, the Extreme Ultraviolet sensor on the Magnetopause-to-Aurora Global Exploration satellite detected the plume near 16:00–17:00 magnetic local time extending outward to L ? 2.8. The plasmaspheric boundary was near L

  10. Storms and Moons

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The New Horizons Long Range Reconnaissance Imager (LORRI) took this 2-millisecond exposure of Jupiter at 04:41:04 UTC on January 24, 2007. The spacecraft was 57 million kilometers (35.3 million miles) from Jupiter, closing in on the giant planet at 41,500 miles (66,790 kilometers) per hour. At right are the moons Io (bottom) and Ganymede; Ganymede's shadow creeps toward the top of Jupiter's northern hemisphere.

    Two of Jupiter's largest storms are visible; the Great Red Spot on the western (left) limb of the planet, trailing the Little Red Spot on the eastern limb, at slightly lower latitude. The Great Red Spot is a 300-year old storm more than twice the size of Earth. The Little Red Spot, which formed over the past decade from the merging of three smaller storms, is about half the size of its older and 'greater' counterpart.

  11. TWINS Geomagnetic Storm Catalog

    NASA Astrophysics Data System (ADS)

    Perez, J. D.; Buzulukova, N.; Fok, M. C. H.; Goldstein, J.; McComas, D. J.; Valek, P. W.; Wood, K. D.

    2014-12-01

    Results from TWINS 1 & 2 observations and CIMI simulations have been cataloged for geomagnetic storms with Dst or SYM/H below -100 nT in the years 2008-2013. TWINS (Two Wide-angle Imaging Neutral-atom Spectrometers) provides ENA (Energetic Neutral Atom) images on a nearly continuous basis over a broad energy range (1-100 keV/amu). CIMI (Comprehensive Inner-Magnetosphere Ionosphere) model combines the ability to simulate ringcurrent dynamics solving for particle distributions and corresponding ENA fluxes with the ability to calculate radiation belt particle fluxes and inner plasma sheet electron precipitation. For each storm, the TWINS Storm Catalog provides 1-hour-samples ENA images, corresponding deconvolved 2D equatorial ion number flux and pitch angle anisotropy, and the energy spectrum and pitch angle distribution at the position of the peak of the number flux. Also included for direct comparison are results from CIMI simulations for the same quantities. The catalog is available to all interested parties. It will be shown how users of the Catalog will have the opportunity to perform a number of studies related to the dynamics of the ring current during geomagnetic storms. For example, the storms cataloged to date show trends in changes of the energy spectrum from high energy tails deficient in ions as compared to a Maxwellian, to a high energy tail and finally approaching a Maxwellian. Likewise, pitch angle distributions are shown to evolve from having more perpendicular than parallel ions to a nearly isotropic distribution. It is also possible to investigate differences in ring current behavior for CIR and ICME driven storms.It is to be noted that in this context, opportunities for results from the measurements and simulations on a finer time scale, for spectra as a function of equatorial position, and similarly for pitch angle distributions are available by request.

  12. Convection Current

    NSDL National Science Digital Library

    The Exploratorium

    2012-06-26

    In this activity, learners make their own heat waves in an aquarium. Warmer water rising through cooler water creates turbulence effects that bend light, allowing you to project swirling shadows onto a screen. Use this demonstration to show convection currents in water as well as light refraction in a simple, visually appealing way.

  13. Modeling Convection

    ERIC Educational Resources Information Center

    Ebert, James R.; Elliott, Nancy A.; Hurteau, Laura; Schulz, Amanda

    2004-01-01

    Students must understand the fundamental process of convection before they can grasp a wide variety of Earth processes, many of which may seem abstract because of the scales on which they operate. Presentation of a very visual, concrete model prior to instruction on these topics may facilitate students' understanding of processes that are largely…

  14. Transient luminous events above two mesoscale convective systems: Charge moment change analysis

    E-print Network

    Rutledge, Steven

    Transient luminous events above two mesoscale convective systems: Charge moment change analysis that were parents of transient luminous events (TLEs; mainly sprites) over two different storms: 9 May (20. A. Rutledge, and D. R. MacGorman (2011), Transient luminous events above two mesoscale convective

  15. Title of Dissertation: AN ANALYSIS OF CONVECTIVE TRANSPORT, LIGHTNING NOX PRODUCTION, AND CHEMISTRY

    E-print Network

    Maryland at College Park, University of

    -cloud aircraft measurements to estimate the ratio most appropriate for each storm. The impact of lightning NOxABSTRACT Title of Dissertation: AN ANALYSIS OF CONVECTIVE TRANSPORT, LIGHTNING NOX PRODUCTION The impact of lightning NOx production and convective transport on tropospheric chemistry was studied in four

  16. Kinetic energy budgets in areas of convection

    NASA Technical Reports Server (NTRS)

    Fuelberg, H. E.

    1979-01-01

    Synoptic scale budgets of kinetic energy are computed using 3 and 6 h data from three of NASA's Atmospheric Variability Experiments (AVE's). Numerous areas of intense convection occurred during the three experiments. Large kinetic energy variability, with periods as short as 6 h, is observed in budgets computed over each entire experiment area and over limited volumes that barely enclose the convection and move with it. Kinetic energy generation and transport processes in the smaller volumes are often a maximum when the enclosed storms are near peak intensity, but the nature of the various energy processes differs between storm cases and seems closely related to the synoptic conditions. A commonly observed energy budget for peak storm intensity indicates that generation of kinetic energy by cross-contour flow is the major energy source while dissipation to subgrid scales is the major sink. Synoptic scale vertical motion transports kinetic energy from lower to upper levels of the atmosphere while low-level horizontal flux convergence and upper-level horizontal divergence also occur. Spatial fields of the energy budget terms show that the storm environment is a major center of energy activity for the entire area.

  17. A Numerical Case Study of Convection Initiation along Colliding Convergence Boundaries in Northeast Colorado.

    NASA Astrophysics Data System (ADS)

    Lee, Bruce D.; Farley, Richard D.; Hjelmfelt, Mark R.

    1991-11-01

    A numerical cloud model has been used to simulate convective storm development on 17 July 1987 in northeast Colorado. The study involves the simulation of convergence along atmospheric boundaries and the subsequent development of convection. The model was initialized using observed conditions for this case day from the Convection Initiation and Downburst Experiment (CINDE).A two-dimensional version of the Clark NCAR nested grid model is employed. Results indicate that convection in boundary line collision cases can be successfully simulated by using actual observed atmospheric data. Gradual deepening of the moisture layer in the convergence zone was shown to destabilize the local atmosphere leading to the initiation of deep convection on this day. The modeled storm approximated the depth and intensity of the observed storms and displayed many of the features of the actual event.Sensitivity studies revealed that the timing and intensity of convection along boundaries is greatly affected by alterations in cross-line values of boundary-layer moisture or convergence and by variations in the vertical wind-shear profile within and above the boundary layer. Increasing the low-level moisture created a much stronger and taller modeled storm that developed much more rapidly. Variations in boundary-layer convergence were shown to affect the timing and character of the modeled storm. Horizontal vorticity in the boundary layer, associated with low-level vertical wind shear, was important for the production of deep convection. When the two air masses collided, deeper lifting was obtained if the opposing vorticity of the moving boundaries was balanced than if one of the vorticity sources was significantly stronger than the other. A threshold value of shear above the boundary layer was shown to inhibit the convective development of the modeled storm. These sensitivity studies emphasize the importance of considering the mesoscale variability of these key parameters in nowcasting convection.

  18. GE Anna Heijbel / The Storm

    E-print Network

    Tian, Weidong

    ImagerPhosphorImager -- galvogalvo scanningscanning 200 µm200 µm 33 20 x 25 cm20 x 25 cm Storm & TyphoonStorm & Typhoon 200 µm200 ·Direct fluorescence ·Chemifluorescence Variable Mode Imaging (VMI) #12;5 / GE Anna Heijbel / Exposure in Typhoon or VDS-CL Fluorescence Scan in Storm Primary Antibody Secondary Antibody -HRP ECL Plus substrate

  19. Seasonal variations of GPS derived TEC at three different latitudes of the southern hemisphere during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Adebiyi, S. J.; Adimula, I. A.; Oladipo, O. A.

    2014-04-01

    Data from the archive of the International GNSS Services (IGS) were used to study the seasonal variations of Total Electron Content (TEC) over three stations located at different latitudes in the southern hemisphere during the geomagnetic storms of 11 January, 6 April, 8 June, and 13 October 2000, representing storms that occurred in summer, autumn equinox, winter and spring equinox, respectively. The percentage TEC deviation with respect to reference values differs substantially from season to season. A strong seasonal anomaly and clear equinoctial asymmetry in TEC response to the storms were observed. Weak and short-lived positive TEC deviations as well as strong and long-lasting negative trends were observed in summer storm during the main and recovery phases respectively over the high and low latitudes whereas in winter storm, the highest positive TEC deviations was recorded during the main phase over the entire latitudes. TEC enhancement dominated all the stations during the autumn (March) equinox storm while TEC depletion was majorly observed during the spring (September) equinox. All these variations find their explanations in the thermospheric composition change and circulation. Future work with direct or modeled measurement of atomic Oxygen to molecular Nitrogen ratio (O/N2), large number of storms and other possible factors such as variations in storm’s intensity and local time dependence of the storm onset is expected to validate the observations in this study.

  20. STORM INLET FILTRATION DEVICE

    EPA Science Inventory

    Five field tests were conducted to evaluate the effectiveness of the Storm and Groundwater Enhancement Systems (SAGES) device for removing contaminants from stormwater. The SAGES device is a three-stage filtering system that could be used as a best management practices (BMP) retr...

  1. Weathering the storm

    SciTech Connect

    Burr, M.T.

    1993-02-01

    When Hurricane Andrew struck, thousands were displaced from their homes in Florida and Louisiana. Now, months after the winds ceased blowing, the storm is causing hardship once again. Insurance companies sustaining large losses in recent months from a number of natural disasters - including the hurricane - are now passing those losses on to their customers. Independent power companies are no exception.

  2. Recovery from major storms

    SciTech Connect

    Holeman, J.S.

    1980-01-01

    Public Service Company of Oklahoma's transmission and distribution system is in tornado alley, and it seems the number of tornados hitting some part of the system is increasing each year. In the past 30 years, Tulsa his been hit 7 times, and experienced 3 very wide and destructive tornado storm systems between 1971 and 1975.

  3. Storm Report Map

    NSDL National Science Digital Library

    This website overlays each day's storms as they occur on a Google Map, pinpointing the location where tornados occurred. The site has data since 5 May 2004, and any day since can be consulted. For particularly impressive sets of tornados, try 2 April 2006 or 12 November 2005.

  4. Oikopolitics, and Storms

    Microsoft Academic Search

    Angela Mitropoulos

    2009-01-01

    In his 2009 Inaugural speech, US President Obama spoke of America's future by not only invoking We the People's faith in founding ideals and documents, but he did so–by this time, as his signature rhetoricity—by evoking storms. Every \\

  5. Total rainfall and convective rainfall in Catalonia, Spain

    NASA Astrophysics Data System (ADS)

    Llasat, M. C.; Puigcerver, M.

    1997-12-01

    A substantial percentage of the total rainfall amount in Catalonia (north-east of Spain) stems from convective cloud systems. To obtain a quantitative estimate, convective events were identified on the charts of a rain-rate recorder from 1960 to 1979. Events were classified into four categories: non-convective, convective with low rainfall rates, convective with moderate to high rates and thunderstorm events. The amount of rain due to each of these was computed. The ratio of convective to total rainfall amounts ranges from 70 to 80 per cent in the summer months to less than 30 per cent in winter and its pattern through the year is discussed as regards regional weather and climate. Orographical features, potential instability of the atmosphere and high sea-surface temperatures are related to high-rate events. The uncertain character of rainfall in the area is clearly linked to the large share of convective rainfall on the bulk precipitation.

  6. Evolution of cloud-to-ground lightning characteristics within the convective region of a midlatitude squall line

    E-print Network

    Billingsley, David Brian

    1994-01-01

    has been examined over a period of 49 minutes. Lightning data from the National Severe Storms Laboratory lightning detection network combined with seven dual-Doppler analyses provided a unique dataset in which to study this Mesoscale Convective System...

  7. An Update to the Warm-Season Convective Wind Climatology of KSC/CCAFS

    NASA Technical Reports Server (NTRS)

    Lupo, Kevin

    2012-01-01

    Total of 1100 convective events in the 17-year warm-season climatology at KSC/CCAFS. July and August typically are the peak of convective events, May being the minimum. Warning and non-warning level convective winds are more likely to occur in the late afternoon (1900-2000Z). Southwesterly flow regimes and wind directions produce the strongest winds. Storms moving from southwesterly direction tend to produce more warning level winds than those moving from the northerly and easterly directions.

  8. Summer Astronomy

    ERIC Educational Resources Information Center

    Riddle, Bob

    2004-01-01

    This brief article describes what can be expected of the skies in the summer of 2004 with quite a few celestial thrills to anticipate. In addition to the planet viewing opportunities, there is a very rare Venus transit of the Sun and the annual Perseid meteor shower. The 2004 summer also marks both an end and beginning for the Cassini/Huygens…

  9. Observations of Convectively Coupled Kelvin Waves forced by Extratropical Wave Activity

    NASA Astrophysics Data System (ADS)

    Kiladis, G. N.; Biello, J. A.; Straub, K. H.

    2012-12-01

    It is well established by observations that deep tropical convection can in certain situations be forced by extratropical Rossby wave activity. Such interactions are a well-known feature of regions of upper level westerly flow, and in particular where westerlies and equatorward wave guiding by the basic state occur at low enough latitudes to interact with tropical and subtropical moisture sources. In these regions convection is commonly initiated ahead of upper level troughs, characteristic of forcing by quasi-geostrophic dynamics. However, recent observational evidence indicates that extratropical wave activity is also associated with equatorial convection even in regions where there is a "critical line" to Rossby wave propagation at upper levels, that is, where the zonal phase speed of the wave is equal to the zonal flow speed. A common manifestation of this type of interaction involves the initiation of convectively coupled Kelvin waves, as well as mixed Rossby-gravity (MRG) waves. These waves are responsible for a large portion of the convective variability within the ITCZ over the Indian, Pacific, and Atlantic sectors, as well as within the Amazon Basin of South America. For example, Kelvin waves originating within the western Pacific ITCZ are often triggered by Rossby wave activity propagating into the Australasian region from the South Indian Ocean extratropics. At other times, Kelvin waves are seen to originate along the eastern slope of the Andes. In the latter case the initial forcing is sometimes linked to a low-level "pressure surge," initiated by wave activity propagating equatorward from the South Pacific storm track. In yet other cases, such as over Africa, the forcing appears to be related to wave activity in the extratropics which is not necessarily propagating into low latitudes, but appears to "project" onto the Kelvin structure, in line with past theoretical and modeling studies. Observational evidence for extratropical forcing of Kelvin and MRG waves will be presented, and the seasonality of these statistical associations will be discussed. Extratropical forcing of equatorial waves appears to be most efficient during the solstice seasons by waves originating within the winter hemisphere and interacting with convection in the summer hemisphere. A companion presentation by J. Biello will examine the theoretical basis for these interactions.

  10. The soundproof dynamical core for COSMO model: representation of convective flows.

    NASA Astrophysics Data System (ADS)

    Wójcik, Damian; Piotrowski, Zbigniew; Rosa, Bogdan; Ziemia?ski, Micha?

    2014-05-01

    Research conducted at Polish Institute of Meteorology and Water Management, National Research Institute, in collaboration with Consortium for Small Scale Modeling (COSMO) are aimed at developing new conservative dynamical core for next generation operational weather prediction model. As the result, a new prototype model was developed with dynamical core based on anelastic set of equation and numerics adopted from the EULAG model. An employment of EULAG allowed to profit from its desirable conservative properties and numerical robustness confirmed in number of benchmark tests and widely documented in scientific literature. The hybrid model consists of EULAG dynamical core implemented into the software environment of the operational COSMO model and basic COSMO physical parameterizations involving turbulence, friction, radiation, moist processes and surface fluxes (COSMO-EULAG). The tool is capable to compute weather forecast in mountainous area for the horizontal resolution of 0.28 km and with slopes reaching 60 degrees of inclination. The presentation is focused on two current research topics. First, the model and especially its dynamics-physics coupling is examined within idealized framework for representation of convective flows. The study is based on two complementary convection benchmarks of Weisman and Klemp (Mon. Wea. Rev. 110:504, 1982) and Grabowski et al. (Q. J. R. Meteorol. Soc. 132:317, 2006). While the first experiment can be used to examine a life cycle of a single convective storm structure in COSMO-EULAG model, the second experiment allows to evaluate the model representation of statistical properties of daytime convective development over land, involving convection initiation as well as is transition into a deep phase. The study involves also the comparison of COSMO-EULAG results with results of standard compressible COSMO-Runge-Kutta model to test the suitability of the anelastic dynamical core for operational mesoscale high-resolution NWP. Next, the results of a realistic case study of Alpine summer convection simulated by COSMO-EULAG with very high horizontal resolutions ranging from 2.2 to 0.28km are presented. While the simulations, even with highest resolution, do not require any artificial orography smoothing, the influence of such smoothing on simulation results is investigated. The study shows e.g. a comparison of flow, cloud and precipitation structure, and spectral analyses of horizontal wind fields. The Cosmo-Eulag forecast is also compared with available meteorological information.

  11. Forecasting Dust Storms - Version 2

    NSDL National Science Digital Library

    2014-09-14

    Forecasting Dust Storms Version 2 provides background and operational information about dust storms. The first part of the module describes dust source regions, the life cycle of a dust storm, and the major types of dust storms, particularly those found in the Middle East. The second part presents a process for forecasting dust storms and applies it to a case in the Middle East. Although the process refers to U.S. Department of Defense models and tools, it can easily be adapted to other forecast requirements and data sources. Note that this module is an updated version of the original one published in 2003.

  12. Convection towers

    DOEpatents

    Prueitt, M.L.

    1994-02-08

    Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode. 5 figures.

  13. Convection Demonstration

    NSDL National Science Digital Library

    Twin Cities Public Television, Inc.

    2007-01-01

    In this quick activity (located on page 2 of the PDF), learners will see the effects of convection and understand what makes hot air balloons rise. Learners will fill a bottle with hot water colored red and another bottle with cold water colored blue, then lower both into a container of water and observe the interaction of liquids of different temperatures/densities. Relates to the linked video, DragonflyTV GPS: Balloon Fiesta.

  14. Convective weather hazards in the Twin Cities Metropolitan Area, MN

    Microsoft Academic Search

    Kenneth A. Blumenfeld

    2008-01-01

    This dissertation investigates the frequency and intensity of severe convective storms, and their associated hazards, in the Twin Cities Metropolitan Area (TCMA), Minnesota. Using public severe weather reports databases and high spatial density rain gauge data, annual frequencies and return-periods are calculated for tornadoes, damaging winds, large hail, and flood-inducing rainfall. The hypothesis that severe thunderstorms and tornadoes are less

  15. Pilot Convective Weather Decision Making in En Route Airspace

    NASA Technical Reports Server (NTRS)

    Wu, Shu-Chieh; Gooding, Cary L.; Shelley, Alexandra E.; Duong, Constance G.; Johnson, Walter W.

    2012-01-01

    The present research investigates characteristics exhibited in pilot convective weather decision making in en route airspace. In a part-task study, pilots performed weather avoidance under various encounter scenarios. Results showed that the margins of safety that pilots maintain from storms are as fluid as deviation decisions themselves.

  16. Comparing the Strength of Eyewall, Inner Rainband, and Outer Rainband Convection Using 10 years of TRMM Data

    Microsoft Academic Search

    H. Jiang; E. M. Ramirez; E. J. Zipser

    2009-01-01

    The Tropical Rain Measuring Mission (TRMM) satellite has passed over more than 900 tropical cyclones since its launch in 1997. Previous studies have established that the intensity of convection in the eyewall (<50~100-km radius from the storm center) is greater than that in the rainbands, and stronger convection often accompanies more intense storms (i.e., defining intensity of the tropical cyclone

  17. Storm water pollution prevention plans

    SciTech Connect

    Rossmiller, R.L. (HDR Engineering, Inc., Bellevue, WA (United States))

    1993-03-01

    National Pollutant Discharge Elimination System (NPDES) general permit applications for industrial storm water discharge were to have been filed by October 1992. The Environmental Protection Agency (EPA) and state agencies are now issuing permits based on these applications. One compliance aspect of the permits is the Storm Water Pollution Prevention Plan (SWP3). The plan must identify the facility's potential sources of storm water pollution and develop and implement best management practices (BMPs) to reduce pollutants in storm water runoff. The objectives of the NPDES storm water program are to eliminate illegal dumping and illicit connections, and to reduce pollutants in industrial storm water discharge. These regulations require industry to develop detailed facility site maps, and describe the types, amounts and locations of potential pollutants. Based on this information, industry can develop and implement best management practices to reduce pollutants in storm water runoff.

  18. THE NOAA HAZARDOUS WEATHER TESTBED: COLLABORATIVE TESTING OF ENSEMBLE AND CONVECTION-ALLOWING WRF MODELS AND SUBSEQUENT

    E-print Network

    Xue, Ming

    THE NOAA HAZARDOUS WEATHER TESTBED: COLLABORATIVE TESTING OF ENSEMBLE AND CONVECTION-ALLOWING WRF NOAA's Hazardous Weather Testbed (HWT) is a joint facility managed by the National Severe Storms Laboratory (NSSL), the Storm Prediction Center (SPC), and the NWS Oklahoma City/Norman Weather Forecast

  19. Winter Storm Lesson Plan

    NSDL National Science Digital Library

    Tasia S.

    2010-09-23

    The subject of this lesson is Winter Storms. The length will be approximately 55 minutes (~15 minutes for each of the three websites and ~10 minutes for the students to create their slideshows). The slideshows may be presented the following day if not enough time is available. This lesson is intended for 4th grade and is directed towards Standard 2 of the 4th grade science core curriculum. This project explores factors that help create severe winter weather. An interactive simulation provides hands-on experience, followed by guiding questions and resource exploration. Winter Storms Connection to Standards: Utah Core Curriculum: Science Standard 2 (Students will understand that the elements of weather can be observed, measured, and recorded to make predictions and determine simple weather patterns.) NETS-T: 1. Facilitate and Inspire Student Learning and Creativity - Students will be using websites and situations that ...

  20. Use of the Aerosonde Unihabited Aerial Vehicle (UAV) in the Fourth Convection and Moisture Experiment (CAMEX 4)

    NASA Technical Reports Server (NTRS)

    Hipskind, R. Stephen; Curry, Judy; Holland, Greg

    2001-01-01

    The Fourth Convection and Moisture Experiment (CAMEX 4) was a scientific field experiment based in Florida in summer 2001 focused on the study of hurricanes off the east coast of the United States. Sponsored by the National Aeronautics and Space Administration's Office of Earth Science, and conducted in collaboration with the National Oceanic and Atmospheric Administration's annual hurricane research program, CAMEX 4 utilized aircraft, ground-based and satellite instrumentation to obtain unprecedented, three dimensional characterizations of these important storms. The Aerosonde UAV was selected by NASA to participate in CAMEX 4 because it provided a unique capability to obtain measurements in the atmospheric boundary layer in and around the storms, unattainable by other platforms or measurement capabilities. This talk focuses on the NASA review process that was followed to coordinate the UAV activity with the conventional aircraft operations, as well as with the other participating agencies and the FAA. We will discuss how Aerosonde addressed the issues of safety, coordination and communication and summarize the lessons learned.

  1. Tropical Severe Local Storms

    NSDL National Science Digital Library

    2014-09-14

    The module provides a brief overview of severe local storms in the tropics. Basic ingredients for thunderstorms and assessment of thunderstorm potential from soundings are described. Then properties and hazards of ordinary thunderstorms, multicellular thunderstorms, supercells are reviewed. Conditions conducive to supercell formation in the tropics are examined along with methods of identifying them in radar and satellite images. Supercell and non-supercell tornado properties and formation are described. Finally, tornadoes, waterspouts, and dust devils properties are compared.

  2. Ice Storm Supercomputer

    ScienceCinema

    None

    2013-05-28

    "A new Idaho National Laboratory supercomputer is helping scientists create more realistic simulations of nuclear fuel. Dubbed 'Ice Storm,' this 2048-processor machine allows researchers to model and predict the complex physics behind nuclear reactor behavior. And with a new visualization lab, the team can see the results of its simulations on the big screen." For more information about INL research, visit http://www.facebook.com/idahonationallaboratory.

  3. Severe Storm Identification with Satellite Microwave Radiometry: An Initial Investigation with Nimbus7 SMMR Data

    Microsoft Academic Search

    Roy W. Spencer; Michael R. Howland; David A. Santek

    1987-01-01

    In an attempt to determine the feasibility of detecting and monitoring severe weather with future satellite passive microwave observations, the severe weather characteristics of convective storms as observed by the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) are investigated. Low 37 GHz brightness temperatures (due to scattering of upwelling radiation by precipitation size ice) were related to the occurrence of

  4. Cloud formation, convection, and stratospheric dehydration

    NASA Astrophysics Data System (ADS)

    Schoeberl, Mark R.; Dessler, Andrew E.; Wang, Tao; Avery, Melody A.; Jensen, Eric J.

    2014-12-01

    Using the Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis winds, temperatures, and anvil cloud ice, we use our domain-filling, forward trajectory model combined with a new cloud module to show that convective transport of saturated air and ice to altitudes below the tropopause has a significant impact on stratospheric water vapor and upper tropospheric clouds. We find that including cloud microphysical processes (rather than assuming that parcel water vapor never exceeds saturation) increases the lower stratospheric average H2O by 10-20%. Our model-computed cloud fraction shows reasonably good agreement with tropical upper troposphere (TUT) cloud frequency observed by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument in boreal winter with poorer agreement in summer. Our results suggest that over 40% of TUT cirrus is due to convection, and it is the saturated air from convection rather than injected cloud ice that primarily contributes to this increase. Convection can add up to 13% more water to the stratosphere. With just convective hydration (convection adds vapor up to saturation), the global lower stratospheric modeled water vapor is close to Microwave Limb Sounder observations. Adding convectively injected ice increases the modeled water vapor to ~8% over observations. Improving the representation of MERRA tropopause temperatures fields reduces stratospheric water vapor by ~4%.

  5. 3D Simulations of methane convective storms on Titan's atmosphere

    Microsoft Academic Search

    R. Hueso; A. Sánchez-Lavega

    2005-01-01

    The arrival of the Cassini\\/Huygens mission to Titan has opened an unprecedented opportunity to study the atmosphere of this satellite. Under the pressure-temperature conditions on Titan, methane, a large atmospheric component amounting perhaps to a 3-5% of the atmosphere, is close to its triple point, potentially playing a similar role as water on Earth. The Huygens probe has shown a

  6. Introducing stochastics into the simulation of convective precipitation events

    NASA Astrophysics Data System (ADS)

    Pistotnik, Georg

    2010-05-01

    In a joint project, the Central Institute for Meteorology and Geodynamics (ZAMG) and the Vienna University of Technology aimed to characterize strong precipitation events and their impact in the Bucklige Welt region in Eastern Austria. Both the region's hydrological and meteorological characteristics, namely its composition of virtually countless small catchments with short response times and a high frequency of summertime convective storms, cause the occurrence of flooding to be strictly tied to convective rainfall events, which is why this study has been focused on this type of precipitation. The meteorological database consists of the ZAMG's high-resolution analysis and nowcasting system INCA ("Integrated Nowcasting through Comprehensive Analysis"), which provides a set of precipitation analyses generated by a statistically optimized combination of rain gauge measurements and radar data with a temporal resolution of 15 minutes and a spatial resolution of 1 kilometre. An intensity threshold of 3.8mm/15min has been used to classify any observed precipitation as a convective one, thus extracting 245 convection days with a total number of almost 1600 individual storm events over the project region out of the 5-year data set from 2003 to 2007. Consecutive analyses were used to compute the motion of these storms, a complex process that could not be completely automatized; due to the repeated occurrence of storm splits or coalescences, a manual control of the automatically provided "suggestion" of movement had to be performed in order to merge two or more precipitation maxima to a single storm if necessary, thus yielding the smoothest and most plausible storm tracks and ensuring a high quality of the database. In the first part of the project, distributions for all characteristic parameters have been derived, including the number of storms per day, their place and time of initiation, their motion, lifetime, maximum intensity and maximum "cell volume" (i.e. overall precipitation per time step). Both components of the mean motion as well as of its deviations could be approximated by normal distributions, whereas the number of storms per day, their lifetime, maximum intensity and maximum cell volume roughly followed exponential distributions. The shapes of the convective cells were approximated by Gaussian bells with the peak intensity and the cell volume as boundary conditions. The temporal courses of the peak intensities and cell volumes were assumed to follow parabolas which are symmetric with respect to the half of the lifetime. In the second part of the project, these distributions were used to drive a random generator that allows simulating an arbitrary number of convection days in order to obtain pseudo time series of convective precipitation for each grid point. An algorithm to create correlated samples of random numbers enabled to also account for the observed correlation between some of the parameters, i.e. lifetime and maximum intensity or maximum cell volume. The spatial structures of the return periods of simulated convective precipitation events may provide valuable additional information when being assimilated to the time series measured by the (unfortunately rather sparse) rain gauges in this region. Thus, further studies have to investigate to what extent the "convection simulator" is able to reproduce these time series. Some iterative fine-tuning of the parameters' distributions as well as an extension of the database to a longer time span may further improve the results and enable to simulate realistic spatio-temporal convection scenarios ("design storms") that have the potential to feed hydrological models and, together with vegetation and soil characteristics, hopefully enable to better assess and regionalize the torrent hazard over the project region.

  7. Structure of the Highly Sheared Tropical Storm Chantal During CAMEX-4

    NASA Technical Reports Server (NTRS)

    Heymsfield, G. M.; Halverson, J.; Ritchie, E.; Simpson, Joanne; Molinari, J.; Tian, L.

    2004-01-01

    NASA's 4th Convection and Moisture Experiment (CAMEX-4) focused on Atlantic hurricanes during the 2001 hurricane season and it involved both NASA and NOAA participation. The NASA ER-2 and DC-8 aircraft were instrumented with unique remote sensing instruments to help increase the overall understanding of hurricanes. This paper is concerned about one of the storms studied, Tropical Storm Chantal, that was a weak storm which failed to intense into a hurricane. One of the practical questions of high importance is why some tropical stoins intensify into hurricanes, and others remain weak or die altogether. The magnitude of the difference between the horizontal winds at lower levels and upper altitudes in a tropical storm, i.e., the wind shear, is one important quantity that can affect the intensification of a tropical storm. Strong shear as was present during Tropical Storm Chantal s lifetime and it was detrimental to its intensification. The paper presents an analysis of unique aircraft observations collected from Chantal including an on-board radar, radiometers, dropsondes, and flight level measurements. These measurements have enabled us to examine the internal structure of the winds and thermal structure of Chantal. Most of the previous studies have involved intense hurricanes that overcame the effects of shear and this work has provided new insights into what prevents a weaker storm from intensifying. The storm had extremely intense thunderstorms and rainfall, yet its main circulation was confined to low levels of the atmosphere. Chantal's thermal structure was not configured properly for the storm to intensify. It is most typical that huricanes have a warm core structure where warm temperatures in upper levels of a storm s circulation help intensify surface winds and lower its central pressure. Chantal had two weaker warm layers instead of a well-defined warm core. These layers have been related to the horizontal and vertical winds and precipitation structure and have helped us learn more about why this storm didn't develop.

  8. Changes of seasonal storm properties in California and Nevada from an ensemble of climate projections

    NASA Astrophysics Data System (ADS)

    Yu, Zhongbo; Jiang, Peng; Gautam, Mahesh R.; Zhang, Yong; Acharya, Kumud

    2015-04-01

    Precipitation characteristics, such as intensity, frequency, duration, and event pattern, are changing due to the increases in greenhouse gases, transition of ocean oscillation phases, etc. In this paper, we evaluate the ability of 11 realizations from multiple regional climate model (RCM)/global climate model pairs in the North American Regional Climate Change Assessment Program (NARCCAP) to simulate the seasonal variability and magnitude of storm properties, including storm duration, interstorm period, and storm intensity. The results indicate that NARCCAP RCMs simulate the seasonal variability better in the Greater Sacramento and San Joaquin than in Las Vegas, which may be due to the RCMs' inability to simulate local convective precipitation associated with the North American Monsoon. We also investigate the impacts of climate change on these storm characteristics by comparing the percentage change and absolute change of storm properties determined from NARCCAP historical runs and future runs. We find that individual RCMs exhibit great uncertainty in the percentage changes in storm duration, interstorm period, and average storm intensity. The ensemble means of storm properties across 11 future NARCCAP RCM projections show different responses to climate change in different locations. Our analyses provide guidelines for selecting the appropriate RCMs for hydrologic studies related to storm properties and provide forecasters and water managers with detailed information of future changes in storm properties so that they can sustainably manage water resources. Our results may also contribute to the nonstationary precipitation scenario development by incorporating the percentage changes of storm properties caused by human-induced warming into the stochastic precipitation model.

  9. Current understanding of magnetic storms: Storm-substorm relationships

    Microsoft Academic Search

    Y. Kamide; W. Baumjohann; I. A. Daglis; W. D. Gonzalez; M. Grande; J. A. Joselyn; R. L. McPherron; J. L. Phillips; E. G. D. Reeves; G. Rostoker; A. S. Sharma; H. J. Singer; B. T. Tsurutani; V. M. Vasyliunas

    1998-01-01

    This paper attempts to summarize the current understanding of the storm\\/substorm relationship by clearing up a considerable amount of controversy and by addressing the question of how solar wind energy is deposited into and is dissipated in the constituent elements that are critical to magnetospheric and ionospheric processes during magnetic storms. (1) Four mechanisms are identified and discussed as the

  10. EarthStorm

    NSDL National Science Digital Library

    EarthStorm is part of the educational outreach of the Oklahoma Climatological Survey (OCS). It provides workshops, lesson plans, classroom activities and potential speakers as resources for K-12 educators. It highlights student projects that use data provided by OCS. Scientific staff are available as mentors. Career information about the atmospheric sciences is also provided. Weather data in terms of weather facts, climate maps, daily weather maps and Oklahoma mesonet information is accessible. Earthstorm also hosts various online forums. Many of the activities focus on the use of Oklahoma mesonet data but are adaptable to other data sources.

  11. Convective heater

    DOEpatents

    Thorogood, R.M.

    1983-12-27

    A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation. 14 figs.

  12. Convective heater

    DOEpatents

    Thorogood, Robert M. (Macungie, PA)

    1986-01-01

    A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation.

  13. Convective heater

    DOEpatents

    Thorogood, Robert M. (Macungie, PA)

    1983-01-01

    A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation.

  14. Outreach Plans for Storm Peak Laboratory

    NASA Astrophysics Data System (ADS)

    Hallar, A. G.; McCubbin, I. B.

    2006-12-01

    The Desert Research Institute (DRI) operates a high elevation facility, Storm Peak Laboratory (SPL), located on the west summit of Mt. Werner in the Park Range near Steamboat Springs, Colorado at an elevation 10,500 ft. SPL provides an ideal location for long-term research on the interactions of atmospheric aerosol and gas- phase chemistry with cloud and natural radiation environments. SPL includes an office-type laboratory room for computer and instrumentation setup with outside air ports and cable access to the roof deck, a full kitchen and two bunk rooms with sleeping space for nine persons. We plan to create a unique summer undergraduate education experiences for students of diversity at Storm Peak Laboratory. As stressed by the College Pathways to Science Education Standards [Siebert and McIntosh, 2001], to support changes in K-12 science education transformations must first be made at the college level, including inquiry-oriented opportunities to engage in meaningful research. These workshops will be designed to allow students to experience the excitement of science, increasing their likelihood of pursing careers within the fields of scientific education or research.

  15. The Deep Convective Clouds and Chemistry (DC3) Field Experiment

    NASA Astrophysics Data System (ADS)

    Barth, M. C.; Brune, W. H.; Cantrell, C. A.; Rutledge, S. A.; Crawford, J. H.; Huntrieser, H.; Homeyer, C. R.; Nault, B.; Cohen, R. C.; Pan, L.; Ziemba, L. D.

    2014-12-01

    The Deep Convective Clouds and Chemistry (DC3) field experiment took place in the central U.S. in May and June 2012 and had the objectives of characterizing the effect of thunderstorms on the chemical composition of the lower atmosphere and determining the chemical aging of upper troposphere (UT) convective outflow plumes. DC3 employed ground-based radars, lightning mapping arrays, and weather balloon soundings in conjunction with aircraft measurements sampling the composition of the inflow and outflow of a variety of thunderstorms in northeast Colorado, West Texas to central Oklahoma, and northern Alabama. A unique aspect of the DC3 strategy was to locate and sample the convective outflow a day after active convection in order to measure the chemical transformations within the UT convective plume. The DC3 data are being analyzed to investigate transport and dynamics of the storms, scavenging of soluble trace gases and aerosols, production of nitrogen oxides by lightning, relationships between lightning flash rates and storm parameters, and chemistry in the UT that is affected by the convection. In this presentation, we give an overview of the DC3 field campaign and highlight results from the campaign that are relevant to the upper troposphere and lower stratosphere region. These highlights include stratosphere-troposphere exchange in connection with thunderstorms, the 0-12 hour chemical aging and new particle formation in the UT outflow of a dissipating mesoscale convective system observed on June 21, 2012, and UT chemical aging in convective outflow as sampled the day after convection occurred and modeled in the Weather Research and Forecasting coupled with Chemistry model.

  16. Estimation of cold ion outflow rates throughout a geomagnetic storm.

    NASA Astrophysics Data System (ADS)

    Haaland, S.

    2014-12-01

    Low energy ions of ionospheric origin are believed to be a significant contributor to the magnetospheric plasma population. Measuring these low energy ions is challenging, though. Spacecraft charging effects usually prevent direct detection using particle detectors.In this paper we suggest a new approach, based on a combination of modelling, synoptic observations and a novel technique to address these issues. We thereafter use this approach to estimate outflow rates and transport of low energy ions during the October 2002 geomagnetic storm selected by the GEM community to benchmark models.Our results indicate large variations in both outflow rates and transportthroughout the various phases of the storm. Prior to the storm main phase, outflow rates are moderate, and the cold ions are mainly emanating from moderately sized polar cap regions. Throughout the main phase of the storm, outflow rates increase and the polar cap source regions expand. Furthermore, faster transport, resulting from enhanced convection, leads to a much larger supply of cold ions to the near Earth region.

  17. Solar System dynamics and global-scale dust storms on Mars

    NASA Astrophysics Data System (ADS)

    Shirley, James H.

    2015-05-01

    Global-scale dust storms occur during the southern summer season on Mars in some Mars years but not in others. We present an updated catalog of Mars years including such storms (n = 9) and Mars years without global-scale storms (n = 11) through the year 2013. A remarkable relationship links the occurrence and non-occurrence of global-scale dust storms on Mars with changes in the orbital angular momentum of Mars with respect to the Solar System barycenter (LMars). All of the global-scale dust storms became planet-encircling in both latitude and longitude during periods when LMars was increasing or near maxima. Statistical significance at the 1% level is obtained for the clustering tendency of LMars phases for the 5 mid-season storms with Ls ranging from 208° to 262° (1956, 1971, 1982, 1994, and 2007). The 11 Mars years without global-scale dust storms exhibit mainly decreasing and minimum values of LMars during the first half of the dust storm season; this tendency is statistically significant at the 5% level. A systematic progression is present in the phasing of the solar irradiance and LMars waveforms for the global-scale storm years. LMars phases for the early season global-scale storms of 1977 and 2001 are advanced in phase with respect to those of the mid-season storms, while the phase for the late season storm of 1973 is delayed with respect to those of the mid-season storms cluster. Factors internal to the Mars climate system, such as a spatial redistribution of surface dust from year to year, must be invoked to account for the non-occurrence of global-scale dust storms in five years (1986, 2003, 2005, 2009, and 2013) when the LMars phase was otherwise favorable. Our results suggest that the occurrence of increasing or peak values of LMars immediately prior to and during the Mars dust storm season may be a necessary-but-not-sufficient condition for the initiation of global-scale dust storms on Mars.

  18. Ionospheric redistribution during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Immel, T. J.; Mannucci, A. J.

    2013-12-01

    The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<-100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3-6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow.

  19. Microsubstances in urban storm water

    Microsoft Academic Search

    Birgitta Horkeby; Per-Arne Malmquist

    1976-01-01

    During 1976 a catchment in Gôteborg was investigated with respect to microsubstances in storm water and atmospheric fallout. The microsubstances studied were 17 heavy metals and PCB, DDT with derivatives, HCB and PAH. The concentrations of heavy metals in storm water were not remarkably high compared with the concentrations in waste water and sometimes in drinking water. For As, Cd,

  20. SOLIDS IN STORM WATER RUNOFF

    Microsoft Academic Search

    Roger B. James

    This paper discusses the way in which storm water solids, particularly total suspended solids (TSS) are defined, sampled and measured. High concentration of pollutants associated with the finer fraction of solids in storm water has seen these particles receive the bulk of management attention. However, it is proposed here that traditional sampling methods commonly used significantly underestimate the mass of

  1. Hydromagnetic Theory of Geomagnetic Storms

    Microsoft Academic Search

    A. J. Dessler; E. N. Parker

    1959-01-01

    A hydromagnetic theory is presented which explains the average characteristics of geomagnetic storms. The magnetic storm is caused by a sudden increase in the intensity of the solar wind. Stresses are then set up in the geomagnetic field by the solar plasma impinging upon the geomagnetic field and becoming trapped in it. These stresses, which are propagated to the earth

  2. Ionospheric redistribution during geomagnetic storms

    PubMed Central

    Immel, T J; Mannucci, A J

    2013-01-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dststorm strength that corresponds closely to the TEC variation but follows it by 3–6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow.

  3. GOES sounding improvement and applications to severe storm nowcasting

    NASA Astrophysics Data System (ADS)

    Li, Zhenglong; Li, Jun; Menzel, W. Paul; Schmit, Timothy J.; Nelson, James P.; Daniels, Jaime; Ackerman, Steven A.

    2008-02-01

    An improved clear-sky physical retrieval algorithm for atmospheric temperature and moisture is applied to the Geostationary Operational Environmental Satellite-12 (GOES-12) Sounder. A comparison with the microwave radiometer (MWR) measured total precipitable water (TPW) at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site from June 2003 to May 2005 shows that the TPW retrievals are improved by 0.4 mm over the legacy GOES Sounder TPW product. The Lifted Index (LI) derived product imagery (DPI) from the improved soundings better depicts the pre-convective environment surrounding a tornadic supercell at Eagle Pass, Texas on 24 April 2007. Another severe storm case from 13 April 2006 demonstrates that the improved physical algorithm successfully detects low-level moisture. Both cases show the new retrievals along with the derived products will help the forecasters with short-term severe storm nowcasting.

  4. Summer Programs.

    ERIC Educational Resources Information Center

    Toussaint, Isabella H.

    An intensive 6-week summer readiness program held in the Beaver Area School District, Beaver, Pennsylvania, developed linguistic facility among 15 preschool children. Daily activities included discussion, picture study, creative arts, field trips, developing experience charts, and other nonlanguage arts activities. A combined experiential,…

  5. Summer Skies

    ERIC Educational Resources Information Center

    Science Scope, 2005

    2005-01-01

    During the evening hours of the summer of 2005, there will be numerous opportunities to observe several of the brighter planets as they move along their respective orbits, overtaking and passing one another, performing a planetary dance with the choreography set to orbital speeds. With the exception of Mars, the visible planets will all be in the…

  6. Summer 2011

    Microsoft Academic Search

    Eric G. Strauss

    2011-01-01

    Cities and the Environment Editor, Eric Strauss, provides an introduction to the Summer 2011 issue. He discusses the journal's transition to its new home at Loyola Marymount University and the creation of the Center for Urban Resilience and Ecological Solution, while underscoring highlights of the special topics section on Urban Predators. The contributors to this section participated in the International

  7. Late-summer inflitration as affected by cropping and grazing management of winter-wheat pastures.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural practices that incorporate grazed winter wheat and associated summer management are vital to the rural economy of the southern Great Plains. In regions where high intensity, late summer storms prevail, limited information exists about the impact of these practices, including chemical fa...

  8. Changes in submerged plants at the South end of Cayuga Lake following Tropical Storm Agnes

    Microsoft Academic Search

    Ray T. Oglesby; Albert Vogel; John H. Peverly; Robert Johnson

    1976-01-01

    Tropical Storm Agnes produced increased suspended sediments and decreased water transparency at the southern end of Cayuga Lake for a sustained period during the early summer of 1972. The 1972 community of submerged vascular plants was severely affected. Standing crops were drastically reduced and the species composition of the plant community changed compared to 1970. In 1973, standing crop values

  9. Hurricane: Storm Science

    NSDL National Science Digital Library

    2000-01-01

    The Miami Museum of Science educational Web site provides a fun and interactive page called Hurricane: Storm Science. The main page consists of a clickable illustration that includes a Inside a Hurricane link where kids can learn what hurricanes are, how they form, and how to understand a radar image; see a cutaway picture of a hurricane; and more. The weather instruments page lets students explore and complete activities on wind, moisture, temperature, air pressure, and weather measuring tools. Other interesting areas of the site include how radar tracks hurricanes, an interactive exercise to learn how this is done, and even stories that have been submitted by people who have survived hurricanes and other disasters.

  10. Inside storm window

    SciTech Connect

    Kaplan, J.I.

    1980-11-01

    The work effort to design, build, install, and evaluate an inside storm window is presented. The ISW, made of two separated layers of mylar (like a thermopane window) which when not in use can be rolled up in a shade, is described. The work effort included: development of a prototype model; the development of production facilities to turn out a small number (50) of ISW's; the production of the windows; the installation of the windows into buildings; the building of a test chamber to determine the R value of the ISW and the subsequent determination of the R value; and a survey to determine how the residents of the homes in which ISW's were installed felt about the windows. Comments on each of these tasks are presented and some comments on initial steps towards commercialization are offered. (MCW)

  11. Dust storm in Chad

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Lake Chad (lower left) and the surrounding wetlands are under increasing pressure from desertification. The encroachment of the Sahara occurs with creeping sand dunes and major dust storms, such as the one pictured in this MODIS image from October 28, 2001. The amount of open water (lighter green patch within the darker one) has declined markedly over the last decades and the invasion of dunes is creating a rippled effect through the wetlands that is all too clear in the high-resolution images. Growing population and increasing demands on the lake give it an uncertain future. The loss of such an important natural resource will have profound effects on the people who depend on the rapidly diminishing source of fresh water. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  12. Inside storm window

    NASA Astrophysics Data System (ADS)

    Kaplan, J. I.

    1980-11-01

    The work effort to design, build, install, and evaluate an inside storm window (ISW) is presented. The ISW, made of two separated layers of mylar (like a thermopane window) which, when not in use can be rolled up in a shade, is described. The work effort included: development of a prototype model; the development of production facilities to turn out a small number (50) of ISW's; the production of the windows; the installation of the windows into buildings; the building of a test chamber to determine the R value of the ISW and the subsequent determination of the R value; and a survey to determine how the residents of the homes in which ISW's were installed felt about the windows.

  13. Spatiotemporal variability of summer precipitation in southeastern Arizona

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Walnut Gulch Experimental Watershed (WGEW) in Southeastern Arizona covers ~150 km2 and receives the majority of its annual precipitation from highly variable and intermittent summer storms during the North American Monsoon. In this study the patterns of precipitation in the United States Departm...

  14. Centralized Storm Information System (CSIS)

    NASA Technical Reports Server (NTRS)

    Norton, C. C.

    1985-01-01

    A final progress report is presented on the Centralized Storm Information System (CSIS). The primary purpose of the CSIS is to demonstrate and evaluate real time interactive computerized data collection, interpretation and display techniques as applied to severe weather forecasting. CSIS objectives pertaining to improved severe storm forecasting and warning systems are outlined. The positive impact that CSIS has had on the National Severe Storms Forecast Center (NSSFC) is discussed. The benefits of interactive processing systems on the forecasting ability of the NSSFC are described.

  15. Modeling Saturn's Giant Storms: Water, Ammonia, and the 30-Year Periodicity

    NASA Astrophysics Data System (ADS)

    Li, C.; Ingersoll, A. P.

    2014-12-01

    A giant planet-encircling storm occurred on Saturn on Dec. 5th, 2010 at planetographic latitude 37.7oN. It produced intense lightning, created enormous cloud disturbances and wrapped around the planet in 6 months. Six such storms, called Great White Spots, have erupted since 1876. They have alternated between mid-latitudes and the equator at intervals ranging from 20 to 30 years. The reason for the intermittent explosion is hitherto unclear and there are no similar storms on brother Jupiter. Here we describe the water-loading-mechanism, which could suppress moist convection for decades due to the larger molecular weight of water in a hydrogen-helium atmosphere. We show that this mechanism requires the deep water vapor mixing ratio to be greater than 1.0%. Observations imply that Saturn's atmosphere is more enriched in water than Jupiter, which could explain why Saturn has such storms and Jupiter does not. We further use a two-dimensional axisymmetric dynamic model and a top-cooling convective adjustment scheme to connect our theory to observation. We show that for a deep water mixing ratio of 1.1%, the ammonia vapor is depleted down to 6 bars, the tropospheric warming is about 6 K, and the interval between two consecutive storms at one place is about 70 years. These values are confirmed by both ground-based and spacecraft observations.

  16. Deep winds beneath Saturn's upper clouds from a seasonal long-lived planetary-scale storm.

    PubMed

    Sánchez-Lavega, A; del Río-Gaztelurrutia, T; Hueso, R; Gómez-Forrellad, J M; Sanz-Requena, J F; Legarreta, J; García-Melendo, E; Colas, F; Lecacheux, J; Fletcher, L N; Barrado-Navascués, D; Parker, D

    2011-07-01

    Convective storms occur regularly in Saturn's atmosphere. Huge storms known as Great White Spots, which are ten times larger than the regular storms, are rarer and occur about once per Saturnian year (29.5 Earth years). Current models propose that the outbreak of a Great White Spot is due to moist convection induced by water. However, the generation of the global disturbance and its effect on Saturn's permanent winds have hitherto been unconstrained by data, because there was insufficient spatial resolution and temporal sampling to infer the dynamics of Saturn's weather layer (the layer in the troposphere where the cloud forms). Theoretically, it has been suggested that this phenomenon is seasonally controlled. Here we report observations of a storm at northern latitudes in the peak of a weak westward jet during the beginning of northern springtime, in accord with the seasonal cycle but earlier than expected. The storm head moved faster than the jet, was active during the two-month observation period, and triggered a planetary-scale disturbance that circled Saturn but did not significantly alter the ambient zonal winds. Numerical simulations of the phenomenon show that, as on Jupiter, Saturn's winds extend without decay deep down into the weather layer, at least to the water-cloud base at pressures of 10-12 bar, which is much deeper than solar radiation penetrates. PMID:21734704

  17. Neonatal thyroid storm accompanied with severe anaemia.

    PubMed

    Cao, Lu-Ying; Wei, Hong; Wang, Zheng-Li

    2015-07-01

    Neonatal thyroid storm is rare; the diagnostic criteria and management of neonatal thyroid storm have not been well established. In this paper, we report a preterm infant diagnosed with neonatal hyperthyroidism secondary to maternal Graves' disease who was discharged after therapy. Unfortunately, he was rehospitalised for neonatal thyroid storm. We will discuss the diagnosis and general therapy of neonatal thyroid storm. PMID:25781522

  18. Storm Water Quality Please report any concerns,

    E-print Network

    California at Santa Cruz, University of

    Storm Water Quality Hotline: Please report any concerns, illegal dumping into storm drains, or suspicious activities that may cause environmental harm to the Storm Water Quality Hotline: (831) 4592553) 4594520 http://cleanwater.ucsc.edu Volunteer and intern with the Storm Water Management Program

  19. A Climatology of Midlatitude Mesoscale Convective Vortices in the Rapid Update Cycle

    E-print Network

    Johnson, Richard H.

    A Climatology of Midlatitude Mesoscale Convective Vortices in the Rapid Update Cycle ERIC P. JAMES of mesoscale convective vortices (MCVs) occurring in the state of Oklahoma during the late spring and summer, true MCVs represent only about 20% of the mesoscale relative vorticity maxima detected by the algorithm

  20. Convective towers detection using GPS radio occultations

    NASA Astrophysics Data System (ADS)

    Biondi, R.; Neubert, T.; Syndergaard, S.; Nielsen, J.

    2010-12-01

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapour mixing ratio and the temperature of the upper troposphere and lower stratosphere. To gain a better understanding of deep convective processes, the study of tropical cyclones could play an important role since they lead to deep convective activity. With this work we want to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. The GPS radio occultation (RO) technique is useful for studying severe weather phenomena because the GPS signals penetrate through clouds and allow measurements of atmospheric profiles related to temperature, pressure, and water vapour with high vertical resolution. Using tropical cyclone best track database and data from different GPS RO missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 hours and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS RO signal is typically larger than the climatology above the tropopause. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses will also be shown to support our hypothesis and to corroborate the idea that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.

  1. The impact of wind shear on mid-latitude convection in convection-allowing WRF simulations.

    NASA Astrophysics Data System (ADS)

    Kennedy, A. D.; Goines, D. C.

    2014-12-01

    Since pioneering studies by Rotunno, Klemp, and Weisman in the 1980s, wind shear has been known to have an important impact on convective storms, controlling mode, strength, and longevity. Despite this knowledge, the impact of wind shear on convection has largely been ignored at the scale of climate models due to a lack of observations. In leiu of these observations, convection-allowing simulations can be used to understand these relationships. Although these simulations are computationally expensive, several institutions maintain large databases of simulations run over the contiguous US in support of the NOAA Hazardous Weather Tesbed (HWT). Multiple years of daily simulations from NSSL and NCEP run in support of this project will be used to understand the relationship between wind shear and convective properties such updraft strength and area. It will be shown that in environments with weak instability, wind shear decreases convective area and strength for areas the size of climate model grids. When sufficient instability is present, however, both of these properties increase with wind shear. Although many of these results are consistent between the NSSL/NCEP simulations, some differences exist. These differences will also be discussed.

  2. Assessment of the Pseudo Geostationary Lightning Mapper Products at the Spring Program and Summer Experiment

    NASA Technical Reports Server (NTRS)

    Stano, Geoffrey T.; Calhoun, Kristin K.; Terborg, Amanda M.

    2014-01-01

    Since 2010, the de facto Geostationary Lightning Mapper (GLM) demonstration product has been the Pseudo-Geostationary Lightning Mapper (PGLM) product suite. Originally prepared for the Hazardous Weather Testbed's Spring Program (specifically the Experimental Warning Program) when only four ground-based lightning mapping arrays were available, the effort now spans collaborations with several institutions and eight collaborative networks. For 2013, NASA's Short-term Prediction Research and Transition (SPoRT) Center and NOAA's National Severe Storms Laboratory have worked to collaborate with each network to obtain data in real-time. This has gone into producing the SPoRT variant of the PGLM that was demonstrated in AWIPS II for the 2013 Spring Program. Alongside the PGLM products, the SPoRT / Meteorological Development Laboratory's total lightning tracking tool also was evaluated to assess not just another visualization of future GLM data but how to best extract more information while in the operational environment. Specifically, this tool addressed the leading request by forecasters during evaluations; provide a time series trend of total lightning in real-time. In addition to the Spring Program, SPoRT is providing the PGLM "mosaic" to the Aviation Weather Center (AWC) and Storm Prediction Center. This is the same as what is used at the Hazardous Weather Testbed, but combines all available networks into one display for use at the national centers. This year, the mosaic was evaluated during the AWC's Summer Experiment. An important distinction between this and the Spring Program is that the Summer Experiment focuses on the national center perspective and not at the local forecast office level. Specifically, the Summer Experiment focuses on aviation needs and concerns and brings together operational forecaster, developers, and FAA representatives. This presentation will focus on the evaluation of SPoRT's pseudo-GLM products in these separate test beds. The emphasis will be on how future GLM observations can support operations at both the local and national scale and how the PGLM was used in combination with other lightning data sets. Evaluations for the PGLM were quite favorable with forecasters appreciating the high temporal resolution, the ability to look for rapid increases in lightning activity ahead of severe weather, as well as situational awareness for where convection is firing and for flight routing.

  3. Dust storm of July 5th 2011, Phoenix, Arizona: Numerical simulation

    NASA Astrophysics Data System (ADS)

    Vukovic, A. J.; Pejanovic, G.; Vujadinovic, M.; Sprigg, W. A.; Nickovic, S.; Djurdjevic, V.

    2011-12-01

    On July 5th 2011 Phoenix (Arizona) was hit with an intensive dust storm (haboob). The National Weather Service estimated the storm reached a peak height of at least 1500 to 1800 m, with a leading edge stretching nearly 100 miles (160 km). The storm traveled at least 240 km., reducing visibility in Phoenix to zero. At about 7 PM MST the dust storm hit the southeast corner of Phoenix and advanced through the entire city area during next two hours. The dust storm was generated by downburst winds associated with strong outflow wind passing over very dry areas with precipitation less than 50% of normal since the end of the 2010 summer. We will present a high-resolution model simulation of this dust storm using the NCEP/NMM non-hydrostatic atmospheric model with embedded DREAM (Dust Regional Weather Prediction Model). MODIS mcd12 data were used to derive dust source masks. Our experiments demonstrated the necessity of using high resolution of both dust sources and dust model in order to simulate this event accurately. In our experiments, the spatial and temporal features of the storm were accurately simulated achieving surface dust concentrations over 1000 ug/m3.

  4. Mosquito Problems after a Storm 

    E-print Network

    Johnsen, Mark

    2008-08-05

    Areas flooded after a severe storm are prone to mosquito problems. Several mosquito species are a danger to humans because of the diseases they transmit. This publication explains the symptoms of dengue fever, West Nile virus and St. Louis...

  5. Mantle Convection Modeling

    NSDL National Science Digital Library

    Yarden Livnat

    This research page provides links to two animations of modeled mantle convection, showing the progression of convection over millions of years. There are also links to other work and publications by the author.

  6. Hydration of the lower stratosphere by ice crystal geysers over land convective systems

    NASA Astrophysics Data System (ADS)

    Khaykin, S.; Pommereau, J.-P.; Korshunov, L.; Yushkov, V.; Nielsen, J.; Larsen, N.; Christensen, T.; Garnier, A.; Lukyanov, A.; Williams, E.

    2009-03-01

    The possible impact of deep convective overshooting over land has been explored by six simultaneous soundings of water vapour, particles and ozone in the lower stratosphere next to Mesoscale Convective Systems (MCSs) during the monsoon season over West Africa in Niamey, Niger in August 2006. The water vapour measurements were carried out using a fast response FLASH-B Lyman-alpha hygrometer. The high vertical resolution observations of the instrument show the presence of accumulation of enhanced water vapour layers between the tropopause at 370 K and the 420 K level. Most of these moist layers are shown connected with overshooting events occurring upwind as identified from satellite IR images over which the air mass probed by the sondes passed during the three previous days. In the case of a local overshoot identified by echo top turrets above the tropopause by the MIT C-band radar also in Niamey, tight coincidence was found between enhanced water vapour, ice crystal and ozone dip layers indicative of fast uplift of tropospheric air across the tropopause. The water vapour mixing ratio in the enriched layers exceeds frequently by 1-3 ppmv the average 6 ppmv saturation ratio at the tropopause and by up to 7 ppmv in the extreme case of local storm in coincidence with the presence of ice crystals. The presence of such layers strongly suggests hydration of the lower stratosphere by geyser-like injection of ice particles over overshooting turrets. The pile-like increase of water vapour up to 19 km seen by the high-resolution hygrometer during the season of maximum temperature of the tropopause, suggests that the above hydration mechanism may contribute to the summer maximum moisture in the lower stratosphere. If this interpretation is correct, hydration by ice geysers across the tropopause might be an important contributor to the stratospheric water vapour budget.

  7. Hurricane and Severe Storm Lenticular

    NSDL National Science Digital Library

    2012-08-26

    This resource is a 4 x 6" lenticular card on NASA's HS3 (Hurricane and Severe Storm Sentinel) aircraft mission, which will overfly tropical storms and hurricanes using NASA's Global Hawk Unmanned Aircraft Systems (UAS) in the Northern Atlantic, Caribbean, and Gulf of Mexico. These flights will improve our understanding of the processes that lead to the development of intense hurricanes. The mission will take place for one-month periods during the 2012, 2013, and 2014 Atlantic Basin hurricane seasons.

  8. Storm detection by electronic means 

    E-print Network

    Wooten, Allen Dewey

    1949-01-01

    of deter- mining (at some future date) the repetition rate of these discharges relative to radar storm detection, 3 I. THEORETICAL CONSIDERATION OF RADAR STORM DETECTION $~da The oz~ The commonly accepted theory of occurrence of radar echoes due... to weather conditions is that an echo is caused by reflection of the radar pulse from water drops or particles in tne atmosphere. For a given characteristic of the outgoing radar pulse the strength of the echo depends upon the mass of water encountered...

  9. Stageverslag Open Cell Convection and

    E-print Network

    Stoffelen, Ad

    Stageverslag Open Cell Convection and Closed Cell Convection S. Noteboom De Bilt, 2007 #12 or otherwise, without prior permission in writing from the publisher. #12;Open Cell Convection and Closed Cell Convection Saskia Noteboom September 2006 #12;#12;Open Cell Convection and Closed Cell Convection Saskia

  10. Deep convection in a low-shear subtropical environment: Cell interactions and merger processes

    Microsoft Academic Search

    James Raghi Stalker

    1997-01-01

    Cell interactions and merger processes within a multicellular storm of the 9 August 1991 CaPE (Convection and Precipitation\\/Electrification Experiment) case are identified from radar observations and further analyzed numerically using the Regional Atmospheric Modeling System (RAMS). As many as 15 deep convective cells were identified during a 44 min analysis period, of which 9 cells were long-lived. A set of

  11. SURFACE TENSION DRIVEN CONVECTION

    E-print Network

    Wang, Shouhong

    SURFACE TENSION DRIVEN CONVECTION DIJKSTRA, SENGUL, WANG INTRODUCTION LINEAR THEORY MAIN THEOREMS CONCLUDING REMARKS DYNAMIC TRANSITIONS OF SURFACE TENSION DRIVEN CONVECTION H.Dijkstra T. Sengul S. Wang #12;SURFACE TENSION DRIVEN CONVECTION DIJKSTRA, SENGUL, WANG INTRODUCTION LINEAR THEORY MAIN THEOREMS

  12. Convection Simulations A. Nordlund

    E-print Network

    Stein, Robert

    Convection Simulations š A. Nordlund Astronomical Observatory, and Theoretical Astrophysics Center State University, East Lansing, MI 48823, U.S.A. Abstract. The abrupt transition from convective convection zone, and properties of the solar p­modes for such direct comparisons between simulations

  13. The Influence of Land Surface Heterogeneities on Heavy Convective Rainfall in the Baltimore-Washington Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Ryu, Young-Hee; Smith, James; Baeck, Mary Lynn; Bou-Zeid, Elie

    2015-04-01

    We perform numerical experiments using the Weather Research and Forecasting model to examine the influence of land surface heterogeneities on heavy convective rainfall in the Baltimore-Washington Metropolitan Area. Numerical experiments are carried out for a storm system (1-2 June 2012) in which heavy rainfall and severe weather were organized in the warm sector ahead of a rapidly moving cold front. As shown in previous studies, the environment is typical of flash flood producing storm systems for urban areas of the eastern US. The storm system produced rainfall accumulations exceeding 80 mm and major flash flooding in Baltimore watersheds. The study region is adjacent to the Chesapeake Bay and includes the second largest urban agglomeration in the eastern US. Numerical experiments examine urban impacts on rainfall using the Princeton Urban Canopy Model and the Noah Land Surface Model. We also examine the role of "Bay Breeze" circulations from the Chesapeake Bay for convective evolution. Rainfall distribution and amount are better represented for experiments using the more realistic urban canopy model. The Bay Breeze plays a central role in formation of convergence lines that are major determinants of convective evolution with the approaching line of convection. The Bay Breeze also interacts with heterogeneous surface fluxes from urban landscapes to determine moisture transport to evolving storm systems. The low-level convergence lines and water vapor transport that are induced and modified by land surface heterogeneities are crucial for the preferred locations of strong convective storms and heavy rainfall over the Baltimore Washington metropolitan area.

  14. Investigation of convective activity by means of sferics

    E-print Network

    Snyder, Louis Archie

    1958-01-01

    in the sferics program. In recent years Jones (4) has observed that sferics associated with tornadoes in tha Oklahoma area were of a much greater amplitude than those accompanying thunderstorms. He found that as the intensity of an individual storm center..., this is the bearing ob- tained by the sferics sets at Oklahoma State University, Stillwater, Oklahoma on convective activity within range of the sferics sets. 6. Sferics intensities. ? a. Sferics bearings: V. H. ? very heavy M. H. ? medium heavy M ? medium...

  15. Satellite observations of electric fields in the South Atlantic anomaly region during the July 2000 magnetic storm

    Microsoft Academic Search

    C. S. Lin; H. C. Yeh

    2005-01-01

    During the great magnetic storm of 15 July 2000 the ROCSAT-1 low Earth-orbiting satellite detected an unusually large region of density depletion at low latitudes (<35°) in the ionosphere in corotation with the South Atlantic anomaly (SAA). Adjacent to the region of density dropout was a region of density enhancement with irregularities. We report characteristics of convective electric fields deduced

  16. Large magnetic storm-induced nighttime ionospheric flows at midlatitudes and their impacts on GPS-based navigation systems

    Microsoft Academic Search

    Su. Basu; S. Basu; E. MacKenzie; P. Doherty; J. W. Wright; F. Rich; M. J. Keskinen; R. E. Sheehan

    2008-01-01

    Analysis of GPS phase fluctuations in conjunction with regional total electron content (TEC) maps, in situ measurements of subauroral polarization streams (SAPS) and auroral convection from several Defense Meteorological Satellite Program spacecraft, and dynasonde measurements at the Bear Lake Observatory obtained during the intense magnetic storm of 7–8 November 2004 have indicated the serious impact of large ionospheric velocities on

  17. Is tropopause folding promoting or suppressing deep convection? First results from TROSIAD

    NASA Astrophysics Data System (ADS)

    Antonescu, B.; Vaughan, G.; Schultz, D. M.

    2012-04-01

    The occurrence, timing, and location of deep, moist convection remains a problem for operational weather forecasting, despite the rapid development of the numerical weather prediction models and implementation of new observational techniques. One impediment to better forecasting of deep convection is the role played by tropopause folds. How deep convection is modulated by tropopause folding, which brings stratospheric air into the troposphere, is not well understood. Three ingredients are required for deep moist, convection- moisture, instability, and lift-and all three ingredients associated with tropopause folds can either promote or suppress convection. For example, the dry air associated with the descent of upper-tropospheric air may limit the vertical development of buoyant thermals, yet this dry air may also create potential instability. The purpose of the research project TROSIAD is to assess the importance for convection forecasting of correctly representing tropopause folds in numerical weather forecasting models and to disentangle the conflicting paradigms that tropopause folds both promote and suppress convection. The work plan of the project involves the analysis of existing data from the Mesosphere-Stratosphere-Troposphere (MST) Radar at Aberystwyth, UK, which can measure both tropopause folds and convection, a number of cases studies from measurement campaigns, and numerical modelling experiments. The project begins with building 5-year (2006-2010) climatologies of radar data, and wind-profiling data to determine the relationship between tropopause folds and deep moist convection. Using data from Met Office NIMROD radar network, a climatology of all convective storms with the track in study region was developed. To be included in the climatology, a convective storm must persist for at least 30 minutes with a maximum radar reflectivity greater than 30 dBZ. A total of 663 convective storms were identified. A climatology of the tropopause folds over Wales was developed based on the MST radar data. Tropopause folds can be identified in the wind speed plots, coinciding with maxima in wind shear and echo power. A total of 231 tropopause folds events were identified. By combining the severe-storm and tropopause-fold climatologies 76 convective storms were associated with tropopause folds. About half of these cases (42%) were observed on the western side of an upper level trough, a region in which the convection is in generally considered as being suppressed. As an exemplification of entangled effects of tropopause folds on convection, two case studies are presented. The first event took place on 24 May 2006, when a cold front has passed over the UK, and convection was associated with moist air moving north-eastward over Wales, and becoming instable when the tropopause due to the presence of dry air in the tropopause fold above. In the second case on 2 December 2006, again associated with the passage of a cold front, the tropopause fold reached a lower attitude in comparison with the first case, suppressing convection. We also studied the morphology of the storms associated with tropopause folds, and we found that 51% of the cases are associated with multicellular convective lines, 25% are isolated cells, and 24% are multicellular clusters.

  18. Estimation of convective mass transfer in solar distillation systems

    Microsoft Academic Search

    Sanjay Kumar; G. N. Tiwari

    1996-01-01

    In this article a thermal model has been developed to determine the convective mass transfer for different Grashof Number range in solar distillatiOn process. The model is based on simple regression analysis. Based on the experimental data obtained from the rigorous outdoor experimentation on passive and active distillation systems for summer climatic conditions, the values of C and n have

  19. Assessing the Potential for Rain Augmentation - The Nelspruit Randomized Convective Cloud Seeding Experiment.

    NASA Astrophysics Data System (ADS)

    Mather, G. K.; Dixon, M. J.; de Jager, J. M.

    1996-09-01

    The experimental design, analyses, and results of the first Nelspruit randomized cloud seeding experiment are described. The experiment ran for three years, commencing in October 1984, and involved the on-top seeding of new cloud turrets growing on the flanks of isolated multicellular storms using dry ice delivered from a Learjet at around the height of the 10°C isotherm. All storms were tracked by a radar operating in computer-controlled volume scan mode. A total of 169 storms were examined, of which 94 passed the selection criteria. The most important criterion was based upon a microphysical classification scheme obtained from measurements made by the instrumented Learjet. This scheme, based upon a ratio of cloud-base temperature to potential buoyancy at 500 mb, rejected those storms in which the production of precipitation via coalescence was unlikely.A key element of the experiment was the ability to objectively track the storms using an automatic storm tracking algorithm. Storms were analyzed in terms of their track properties, some of the more important of which were storm volume, area, and rain flux. Analyses of these track properties in 10-min time intervals either side of decision time (the time the seed/no-seed decision was made) proved to be the most revealing in terms of observed changes and rates of changes in convective cloud processes. This analysis showed an almost fourfold percentage increase in radar-measured rain flux and storm area when the seeded and control storms were compared.A confirmatory experiment was conducted in the third season. Storm track properties that showed an apparent response to seeding in each of the first two seasons were selected prior the commencement of the third season. All but one of these track properties either stayed the same or showed increases in the third season, confirming the hypothesis that there were radar-detected differences between the seeded and control storms.

  20. Behavior and Characteristics of Storm Cold Outflows.

    NASA Astrophysics Data System (ADS)

    Lucero, Omar Abel

    The governing dynamics of storm cold outflows was studied using a hydrostatic cold outflow model and the results verified against observations. Results indicate that asymmetries in wind pattern inside the cold outflow and in spreading are produced by the constant modification of the pressure field inside the cold outflow caused by the movement of the downdraft. The cold outflow can maintain its maximum depth up to a threshold travel speed of the downdraft. For downdrafts travelling faster than the threshold speed, which depends on the downdraft's rate of discharge, that maximum depth decreases. The rate of spread of a cold outflow is also profoundly influenced by the downdraft's travel speed. Analyses of pressure and surface winds beneath strong convection during the arrival of two downbursts at the ground showed that they satisfy the Bernoulli equation. This is interpreted to indicate that pressure forces play an important role in the occurrence of surface windburst caused by the arrival of a downburst. At the time of arrival of the downbursts at the surface, thermodynamic analyses suggested that the air had descended from a dry layer at 700-760 hPa. A case of a downburst produced by a convective cell generated by a cold outflow collision was studied. The changes in the near surface flow brought about the collision of cold outflows were analyzed. During the sudden demise of a group of strong convective cells, due to low level mesoscale air interception by a cold outflow, no increase in rainfall production was detected that would suggest downburst occurrence despite that downbursts were occurring in another location of the mesonet. The components in the equation for the rate of change of relative vertical surface vorticity were computed for two days during the VIN (Virginia-Illinois-NOAA) experiment. The contribution of the combined action of the vertical advection and tilting terms were found to be more important to the rate of change of relative surface vorticity than the convergence term contribution in the area of the mesonet. However, the latter contribution cannot be neglected when strong downdrafts are present inside the mesonet.

  1. Meteorological aspects associated with dust storms in the Sistan region, southeastern Iran

    NASA Astrophysics Data System (ADS)

    Kaskaoutis, D. G.; Rashki, A.; Houssos, E. E.; Mofidi, A.; Goto, D.; Bartzokas, A.; Francois, P.; Legrand, M.

    2015-07-01

    Dust storms are considered natural hazards that seriously affect atmospheric conditions, ecosystems and human health. A key requirement for investigating the dust life cycle is the analysis of the meteorological (synoptic and dynamic) processes that control dust emission, uplift and transport. The present work focuses on examining the synoptic and dynamic meteorological conditions associated with dust-storms in the Sistan region, southeastern Iran during the summer season (June-September) of the years 2001-2012. The dust-storm days (total number of 356) are related to visibility records below 1 km at Zabol meteorological station, located near to the dust source. RegCM4 model simulations indicate that the intense northern Levar wind, the high surface heating and the valley-like characteristics of the region strongly affect the meteorological dynamics and the formation of a low-level jet that are strongly linked with dust exposures. The intra-annual evolution of the dust storms does not seem to be significantly associated with El-Nino Southern Oscillation, despite the fact that most of the dust-storms are related to positive values of Oceanic Nino Index. National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis suggests that the dust storms are associated with low sea-level pressure conditions over the whole south Asia, while at 700 hPa level a trough of low geopotential heights over India along with a ridge over Arabia and central Iran is the common scenario. A significant finding is that the dust storms over Sistan are found to be associated with a pronounced increase of the anticyclone over the Caspian Sea, enhancing the west-to-east pressure gradient and, therefore, the blowing of Levar. Infrared Difference Dust Index values highlight the intensity of the Sistan dust storms, while the SPRINTARS model simulates the dust loading and concentration reasonably well, since the dust storms are usually associated with peaks in model simulations.

  2. Meteorological aspects associated with dust storms in the Sistan region, southeastern Iran

    NASA Astrophysics Data System (ADS)

    Kaskaoutis, D. G.; Rashki, A.; Houssos, E. E.; Mofidi, A.; Goto, D.; Bartzokas, A.; Francois, P.; Legrand, M.

    2014-06-01

    Dust storms are considered natural hazards that seriously affect atmospheric conditions, ecosystems and human health. A key requirement for investigating the dust life cycle is the analysis of the meteorological (synoptic and dynamic) processes that control dust emission, uplift and transport. The present work focuses on examining the synoptic and dynamic meteorological conditions associated with dust-storms in the Sistan region, southeastern Iran during the summer season (June-September) of the years 2001-2012. The dust-storm days (total number of 356) are related to visibility records below 1 km at Zabol meteorological station, located near to the dust source. RegCM4 model simulations indicate that the intense northern Levar wind, the high surface heating and the valley-like characteristics of the region strongly affect the meteorological dynamics and the formation of a low-level jet that are strongly linked with dust exposures. The intra-annual evolution of the dust storms does not seem to be significantly associated with El-Nino Southern Oscillation, despite the fact that most of the dust-storms are related to positive values of Oceanic Nino Index. National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis suggests that the dust storms are associated with low sea-level pressure conditions over the whole south Asia, while at 700 hPa level a trough of low geopotential heights over India along with a ridge over Arabia and central Iran is the common scenario. A significant finding is that the dust storms over Sistan are found to be associated with a pronounced increase of the anticyclone over the Caspian Sea, enhancing the west-to-east pressure gradient and, therefore, the blowing of Levar. Infrared Difference Dust Index values highlight the intensity of the Sistan dust storms, while the SPRINTARS model simulates the dust loading and concentration reasonably well, since the dust storms are usually associated with peaks in model simulations.

  3. Injection boundary dynamics during a geomagnetic storm

    NASA Technical Reports Server (NTRS)

    Konradi, A.; Semar, C. L.; Fritz, T. A.

    1976-01-01

    A series of proton and electron injections were observed by Explorer 45 associated with several substorms during the main phase of the Feb. 24, 1972 geomagnetic storm. The 1- to 290-keV protons and 1- to 560-keV electrons were observed in the evening quadrant up to L of about 5.2. A model distorted dipole magnetic field and McIlwain's E3 convection electric field were used to backtrack the energy-dispersed electron and proton fluxes to their source at the time of injection. The source turns out to be a region extending over several earth radii outside an injection boundary. In the night magnetosphere, the inferred injection boundary is displaced inward with each successive substorm. The energy dispersion plot of the particles injected during orbit 314 indicates that as the energy of the observed particles decreases there is a smooth transition to the position of the plasmapause. This suggests that for that substorm the injection boundary and the plasmapause were one and the same. The proton 'noses' reported by Smith and Hoffman (1974) are discussed.

  4. High-Resolution Simulation of Hurricane Bonnie (1998): Storm Structure and Evolution

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.; Pu, Zhaoxia; Starr, David OC. (Technical Monitor)

    2002-01-01

    A simulation of Hurricane Bonnie (1998) has been performed using multiple grid nesting to 2 km grid spacing. The simulation is initialized with large-scale analysis fields from the European Center for Medium Range Forecasts and with a bogus vortex inserted via four-dimensional variational data assimilation. The simulation, verified against radar observations from TRMM and aircraft observations from the NASA CAMEX-3 field experiment, reproduces well the storm intensity, the wavenumber 1 asymmetry of the precipitation field, the occurrence of deep convective towers within the eyewall, and the presence of broad stratiform precipitation regions. This study will explore the evolution of air parcels in these convective towers, from their beginnings in the boundary layer to their movement in upper level outflow. The role of these towers in storm intensification may also be examined.

  5. Dynamics governing the collapse of the typical Etesians wind pattern over the eastern Mediterranean during summer 2002

    NASA Astrophysics Data System (ADS)

    Tyrlis, Evangelos; Lelieveld, Jos

    2014-05-01

    The summer circulation over the Eastern Mediterranean (EM) is dominated by large-scale subsidence and a persistent northerly flow (Etesians) featuring a July-August maximum. Both phenomena are key ingredients of the characteristic Mediterranean-type climate and their annual recurrence is controlled by the summer South Asian monsoon. The large-scale signal induced by the monsoon is often enhanced or masked by higher frequency variability originating in the mid-latitudes. Thus, the summer EM circulation variability is a fusion of mid-latitude and direct tropical influences on various timescales. This study attempts to untangle the signal contributions from these two sources during the summer of 2002, an extreme case of collapse of the Etesians and subsidence over the EM especially during July. The daily evolution of the synoptic conditions leading to this collapse is investigated, while the use of daily indices allows the study of the detailed evolution of the intensity of the monsoon and the Etesians, as well as their relation. This major climatic anomaly coincided with prolonged spells of major failure of the Indian Monsoon. Under normal monsoon activity, frequent Rossby wave 'pulses' are triggered by outbreaks of deep convection over the region. This activity takes the form of sharply-defined warm anomalies associated with stronger than normal subsidence that travel westward and reach the EM within a week. During most of July and early August 2002 this activity is absent or very weak, which is indicative of the possible importance of the monsoon failure for the relaxation of subsidence over the EM. However, the mid-latitude dynamics appear to play a crucial role by controlling the exact timing of the collapse of EM subsidence and the Etesians that potentially enhance the monsoon induced signal. Frequent development of blocking anticyclones over northern Europe that often appear to retrogress towards the Atlantic are the dominant circulation feature during this period. Unseasonably deep cut off lows that are part of the blocking dipole formation develop over the Mediterranean that bring unsettled weather resulting in the southern displacement of the mid-latitude storm track. All the observed spells of convective activity and weakening of the Etesians over the EM coincide with the formation of these cut-off lows. The anomalous southerly flow over the Mediterranean (weak Etesians) lead to the northward moisture transport towards central Europe that contributed to the well-known European floods and it can be seen as an integral component of the observed continental-scale climatic anomaly.

  6. Storm tracks near marginal stability

    NASA Astrophysics Data System (ADS)

    Ambaum, Maarten; Novak, Lenka

    2015-04-01

    The variance of atmospheric storm tracks is characterised by intermittent bursts of activity interspersed with relatively quiescent periods. Most of the poleward heat transport by storm tracks is due to a limited number of strong heat flux events, which occur in a quasi-periodic fashion. This behaviour is in contradiction with the usual conceptual model of the storm tracks, which relies on high growth rate background flows which then spawn weather systems that grow in an exponential or non-normal fashion. Here we present a different conceptual model of the atmospheric storm tracks which is built on the observation that, when including diabatic and other dissipative effects, the storm track region is in fact most of the time marginally stable. The ensuing model is a nonlinear oscillator, very similar to Volterra-Lotka predator-prey models. We demonstrate the extensions of this model to a stochastically driven nonlinear oscillator. The model produces quasi-periodic behaviour dominated by intermittent heat flux events. Perhaps most surprisingly, we will show strong evidence from re-analysis data for our conceptual model: the re-analysis data produces a phase-space plot that is very similar indeed to the phase-space plot for our nonlinear oscillator model.

  7. Mechanisms initiating deep convection over complex terrain during COPS.

    SciTech Connect

    Kottmeier, C.; Kalthoff, N.; Barthlott, C.; Corsmeier, U.; Van Baelen, J.; Coulter, R.; Environmental Science Division; Inst. for Meteorology and Climate Research; Lab. de Meteorologie Physique; Inst. of Physics and Meteorology

    2008-12-01

    Precipitating convection in a mountain region of moderate topography is investigated, with particular emphasis on its initiation in response to boundary-layer and mid- and upper-tropospheric forcing mechanisms. The data used in the study are from COPS (Convective and Orographically-induced Precipitation Study) that took place in southwestern Germany and eastern France in the summer of 2007. It is found that the initiation of precipitating convection can be roughly classified as being due to either: (i) surface heating and low-level flow convergence; (ii) surface heating and moisture supply overcoming convective inhibition during latent and/or potential instability; or (iii) mid-tropospheric dynamical processes due to mesoscale convergence lines and forced mean vertical motion. These phenomena have to be adequately represented in models in order to improve quantitative precipitation forecast. Selected COPS cases are analyzed and classified into these initiation categories. Although only a subset of COPS data (mainly radiosondes, surface weather stations, radar and satellite data) are used here, it is shown that convective systems are captured in considerable detail by sensor synergy. Convergence lines were observed by Doppler radar in the location where deep convection is triggered several hours later. The results suggest that in many situations, observations of the location and timing of convergence lines will facilitate the nowcasting of convection. Further on, forecasting of the initiation of convection is significantly complicated if advection of potentially convective air masses over changing terrain features plays a major role. The passage of a frontal structure over the Vosges - Rhine valley - Black Forest orography was accompanied by an intermediate suppression of convection over the wide Rhine valley. Further downstream, an intensification of convection was observed over the Black Forest due to differential surface heating, a convergence line, and the flow generated by a gust front.

  8. Environment and evolution of a cold-frontal mesoscale convective system

    NASA Technical Reports Server (NTRS)

    Trier, Stanley B.; Parsons, David B.; Clark, John H. E.

    1991-01-01

    Data obtained from the June 26-27, 1985 period of the Kansas-Oklahoma PRE-STORM field phase are employed to describe the evolution of a mesoscale convective system (MCS) responsible for a heavy rainfall event over a large portion of Oklahoma and Kansas. In the case examined, the eastward advancement of deep convection was aided by the formation of a series of nearly parallel rainbands before the main precipitation area. These rainbands, which developed in a field of boundary layer cloud streets, without the assistance of gust-front convergence, redefined the leading edge of the MCS and became the locus of the most intense convection in the precipitation system.

  9. Evaluation of the model representation of the evolution of convective systems using satellite observations of outgoing longwave radiation

    NASA Astrophysics Data System (ADS)

    Pearson, K. J.; Hogan, R. J.; Allan, R. P.; Lister, G. M. S.; Holloway, C. E.

    2010-10-01

    We introduce a technique for assessing the diurnal development of convective storm systems based on outgoing longwave radiation fields. Using the size distribution of the storms measured from a series of images, we generate an array in the length scale-time domain based on the standard score statistic. It demonstrates succinctly the size evolution of storms as well as the dissipation kinematics. It also provides evidence related to the temperature evolution of the cloud tops. We apply this approach to a test case comparing observations made by the Geostationary Earth Radiation Budget instrument to output from the Met Office Unified Model run at two resolutions. The 12 km resolution model produces peak convective activity on all length scales significantly earlier in the day than shown by the observations and no evidence for storms growing in size. The 4 km resolution model shows realistic timing and growth evolution, although the dissipation mechanism still differs from the observed data.

  10. Effects of Tropospheric Wind Shear on the Spectrum of Convectively Generated Gravity Waves.

    NASA Astrophysics Data System (ADS)

    Beres, Jadwiga H.; Alexander, M. Joan; Holton, James R.

    2002-06-01

    The authors examine the effects of tropospheric wind shear on the phase speed spectrum of gravity waves generated by tropical convection. A two-dimensional cloud-resolving model is used to perform numerous squall line simulations with the vertical shear of the horizontal wind varied in three layers of the troposphere. Several simplified simulations using prescribed heating are also performed to elucidate the interactions of wind shear with thermal forcing. It is found that the dominant phase speed range of convectively generated stratospheric gravity waves is primarily determined by the vertical scale of the tropospheric heating and is then modified by the tropospheric wind. The gravity wave spectrum is especially sensitive to shear in the upper troposphere. Through a mechanism similar to critical level filtering, such shear acts to reduce the momentum flux of waves propagating in the same direction as the storm-relative mean wind. Through interaction with convective turrets, shear in the upper troposphere increases the momentum flux of waves propagating opposite to the storm-relative mean wind (the `obstacle effect'). The resulting spectrum of momentum fluxes produced by convectively generated gravity waves is generally not symmetric in the east and west directions; the east-west asymmetry depends primarily on the difference between the wind above the storm and the storm's motion. Thus, it is important that the effects of tropospheric wind shear be included in any attempt to parameterize the effects of gravity wave stress and turbulence in general circulation models.

  11. Silver iodide seeding impact on the microphysics and dynamics of convective clouds in the high plains

    Microsoft Academic Search

    Baojun Chen; Hui Xiao

    2010-01-01

    The concept of dynamic seeding is a physically plausible hypothesis but has not yet been confirmed by observations or numerical simulations. To verify the hypothesis of dynamic seeding, a three-dimensional nonhydrostatic cloud model with two-moment bulk microphysics scheme has been used to investigate the effects of silver iodide seeding on cloud microphysics, dynamics and precipitation of convective storms. Eight species

  12. Convective Modes for Significant Severe Thunderstorms in the Contiguous United States. Part III: Tropical Cyclone Tornadoes

    E-print Network

    : Tropical Cyclone Tornadoes ROGER EDWARDS, ANDREW R. DEAN, RICHARD L. THOMPSON, AND BRYAN T. SMITH NWS Storm of the SPC tropical cyclone (TC) tornado records. Distributions of environmental convective parameters, derived from SPC hourly mesoanalysis fields that have been related to supercells and tornadoes

  13. The Tropical Convective Spectrum. Part 1; Archetypal Vertical Structures

    NASA Technical Reports Server (NTRS)

    Boccippio, Dennis J.; Petersen, Walter A.; Cecil, Daniel J.

    2005-01-01

    A taxonomy of tropical convective and stratiform vertical structures is constructed through cluster analysis of 3 yr of Tropical Rainfall Measuring Mission (TRMM) "warm-season" (surface temperature greater than 10 C) precipitation radar (PR) vertical profiles, their surface rainfall, and associated radar-based classifiers (convective/ stratiform and brightband existence). Twenty-five archetypal profile types are identified, including nine convective types, eight stratiform types, two mixed types, and six anvil/fragment types (nonprecipitating anvils and sheared deep convective profiles). These profile types are then hierarchically clustered into 10 similar families, which can be further combined, providing an objective and physical reduction of the highly multivariate PR data space that retains vertical structure information. The taxonomy allows for description of any storm or local convective spectrum by the profile types or families. The analysis provides a quasi-independent corroboration of the TRMM 2A23 convective/ stratiform classification. The global frequency of occurrence and contribution to rainfall for the profile types are presented, demonstrating primary rainfall contribution by midlevel glaciated convection (27%) and similar depth decaying/stratiform stages (28%-31%). Profiles of these types exhibit similar 37- and 85-GHz passive microwave brightness temperatures but differ greatly in their frequency of occurrence and mean rain rates, underscoring the importance to passive microwave rain retrieval of convective/stratiform discrimination by other means, such as polarization or texture techniques, or incorporation of lightning observations. Close correspondence is found between deep convective profile frequency and annualized lightning production, and pixel-level lightning occurrence likelihood directly tracks the estimated mean ice water path within profile types.

  14. Radar reflectivities and satellite imagery of severe storms 20 May 1977

    NASA Technical Reports Server (NTRS)

    Wexler, R.; Blackmer, R. H., Jr.

    1982-01-01

    Storms on 20 May 1977 generated a vast cirrus deck. Disturbed areas at storm top had equivalent black-body temperatures (T sub BB) much lower than the tropopause temperature, indicative of overshooting tops. The area of T sub BB not greater than -71 C represents the area of convective activity penetrating 2 km above the tropopause. This area was relatively large after cloud tops and radar reflectivities reached their maximum heights. It became much smaller during tornadoes when reflectivities were decreasing. T sub BB was at a minimum at the time of mesocyclone formation. The Del City storm had two periods of growth, as indicated both by reflectivities and the T sub BB areas. The mesocyclone was first detected during the second less intense period of growth; the tornado occurred during decreasing reflectivities. The maintenance of large areas of relatively low T sub BB after tornado dissipation is ascribed to continued convection on the flanks of the storm and to residual updrafts in a thick anvil cloud.

  15. Overview of midlatitude ionospheric storms

    NASA Astrophysics Data System (ADS)

    Kintner, Paul; Coster, Anthea; Fuller-Rowell, Tim; Mannucci, Anthony J.

    Solar flares and coronal mass ejections erupting from the roiling Sun can smash into the Earth's magnetosphere causing geomagnetic storms that penetrate deep into the atmosphere, which can short out satellites, upset radio communications, disrupt navigation, and even damage terrestrial electrical power grids. Though effects on other regions of the atmosphere have been analyzed, the mechanism by which geomagnetic storms influence the ionosphere's middle latitudes remains poorly understood.This brief report provides an overview of current knowledge in midlatitude ionospheric dynamics and disturbances, from the historic record to recent discoveries presented at a January AGU Chapman Conference.

  16. Intraseasonal Teleconnection between the Summer Eurasian Wave Train and the Indian Monsoon

    Microsoft Academic Search

    Qinghua Ding; Bin Wang

    2007-01-01

    This study investigated the most recurrent coupled pattern of intraseasonal variability between midlati- tude circulation and the Indian summer monsoon (ISM). The leading singular vector decomposition (SVD) pattern reveals a significant, coupled intraseasonal variation between a Rossby wave train across the Eurasian continent and the summer monsoon convection in northwestern India and Pakistan (hereafter referred to as NISM). The wave

  17. Moist convection of Neptune

    SciTech Connect

    Stoker, C.R.; Toon, O.B. (NASA Ames Research Center, Moffett Field, CA (USA))

    1989-08-01

    The authors present a study of methane moist convection on Neptune. They examine the stability conditions to initiate moist convection of methane clouds. Temperature lapse rates that are unstable to moist convection are subadiabatic by a factor of two or more while adiabatic and superadiabatic lapse rates are stable. In the observed Neptune temperature structure, vertical velocities {>=} 40 m s{sup {minus}1} are required to lift moist air above the stable region and initiate moist convection. Alternatively, moist convection could be initiated by air that is slightly drier than its surroundings. Moist convective clouds achieve altitudes up to 100 mb, thereby exceeding the temperature minimum and depositing methane in the Neptune stratosphere. They predict that at least 2000 such clouds penetrate the Neptune stratosphere per hour.

  18. Distribution of auroral precipitation at midnight during a magnetic storm

    SciTech Connect

    Sandahl, I.; Eliasson, L.; Pellinen-Wannberg, A. (Swedish Inst. of Space Physics, Kiruna (Sweden)); Rostoker, G. (Univ. of Alberta, Edmonton (Canada)); Block, L.P. (Royal Inst. of Tech., Stockholm (Sweden)); Erlandson, R.E. (Johns Hopkins Univ., Laurel, MD (United States)); Friis-Christensen, E. (Danish Meteorological Inst., Copenhagen (Denmark)); Jacobsen, B. (Univ. of Oslo (Norway)); Luehr, H. (Technischen Univ., Braunschweig (West Germany)); Murphree, J.S. (Univ. of Calgary, Alberta (Canada))

    1990-05-01

    On the night of November 4, 1986, a very complex precipitation pattern was observed by Viking in the magnetic midnight sector over Scandinavia and Svalbard. The pass took place during a magnetic storm, and during substorm recovery phase. Going from north to south, the satellite first encountered a plasma region of BPS-type (name derived from boundary plasma sheet) and then a region of CPS type (derived from central plasma sheet). Then, however, a new region of BPS-type was traversed. The quite intense, most equatorward aurora corresponded to a plasma region which was not of ordinary CPS type but contained sharp quasi-monoenergetic peaks. The high-latitude midnight sector was totally dominated by eastward convection. The Harang discontinuity had passed northern Scandinavia the first time as early as 17 to 20 MLT, more than three house before the Viking pass. It is suggested that the particle precipitation pattern and the general shape of the aurora as observed by the Viking imager can be explained in a natural way by the convection pattern. The northernmost BPS- and CPS-type regions originated in the morningside convection cell, while the more equatorward population of BPS type had drifted in from the eveningside. The interpretation is supported by ground-based measurements by EISCAT and magnetometers.

  19. A long-lived mesoscale convective complex. II - Evolution and structure of the mature complex

    NASA Technical Reports Server (NTRS)

    Wetzel, P. J.; Cotton, W. R.; Mcanelly, R. L.

    1983-01-01

    The present investigation is concerned with an eight-day episode, during which a series of mesoscale convective complexes (MCC) developed and moved across the country, producing heavy rain and some flooding over an extensive region. An overview of the considered period from August 3 to August 10, 1977 is presented, and the evolution of the August 4 storm is examined. The structure of the mature MCC is discussed, taking into account the August 4-5 storm, a comparative case involving the August 3-4 storm, and an evaluation of the observed phenomena. It is concluded that MCCs are basically tropical in nature and that their dynamics are dominated by buoyant accelerations. It was found that the MCCs developed a warm-core, divergent anticyclonic flow pattern in the upper troposphere which was not present prior to the development of convection. A similar structure is observed in tropical cloud clusters.

  20. Electron acceleration in solar noise storms

    E-print Network

    Prasad Subramanian

    2007-01-23

    We present an up-to-date review of the physics of electron acceleration in solar noi se storms. We describe the observed characteristics of noise storm emission, emphasi zing recent advances in imaging observations. We briefly describe the general method ology of treating particle acceleration problems and apply it to the specific proble m of electron acceleration in noise storms. We dwell on the issue of the efficiency of the overall noise storm emission process and outline open problems in this area.

  1. Convection forced by a descending dry layer and low-level moist convergence

    NASA Astrophysics Data System (ADS)

    Russell, Andrew; Vaughan, Geraint; Norton, Emily G.; Ricketts, Hugo M. A.; Morcrette, Cyril J.; Hewison, Tim J.; Browning, Keith. A.; Blyth, Alan M.

    2009-03-01

    A narrow line of convective showers was observed over southern England on 18 July 2005 during the Convective Storm Initiation Project (CSIP). The showers formed behind a cold front (CF), beneath two apparently descending dry layers (i.e. sloping so that they descended relative to the instruments observing them). The lowermost dry layer was associated with a tropopause fold from a depression, which formed 2 d earlier from a breaking Rossby wave, located northwest of the UK. The uppermost dry layer had fragmented from the original streamer due to rotation around the depression (This rotation was also responsible for the observations of apparent descent-ascent would otherwise be seen behind a CF). The lowermost dry layer descended over the UK and overran higher ?w air beneath it, resulting in potential instability. Combined with a surface convergence line (which triggered the convection but had less impact on the convective available potential energy than the potential instability), convection was forced up to 5.5 km where the uppermost dry layer capped it. The period when convection was possible was very short, thus explaining the narrowness of the shower band. Convective Storm Initiation Project observations and model data are presented to illustrate the unique processes in this case.

  2. Global lightning and severe storm monitoring from GPS orbit

    SciTech Connect

    Suszcynsky, D. M. (David M.); Jacobson, A. R.; Linford, J (Justin); Pongratz, M. B. (Morris B.); Light, T. (Tracy E.); Shao, X. (Xuan-Min)

    2004-01-01

    Over the last few decades, there has been a growing interest to develop and deploy an automated and continuously operating satellite-based global lightning mapper [e.g. Christian et al., 1989; Weber et al., 1998; Suszcynsky et al., 2000]. Lightning is a direct consequence of the electrification and breakdown processes that take place during the convective stages of thunderstorm development. Satellite-based lightning mappers are designed to exploit this relationship by using lightning detection as a proxy for remotely identifying, locating and characterizing strong convective activity on a global basis. Global lightning and convection mapping promises to provide users with (1) an enhanced global severe weather monitoring and early warning capability [e.g. Weber et al., 1998] (2) improved ability to optimize aviation flight paths around convective cells, particularly over oceanic and remote regions that are not sufficiently serviced by existing weather radar [e.g. Weber et al., 1998], and (3) access to regional and global proxy data sets that can be used for scientific studies and as input into meteorological forecast and global climatology models. The physical foundation for satellite-based remote sensing of convection by way of lightning detection is provided by the basic interplay between the electrical and convective states of a thundercloud. It is widely believed that convection is a driving mechanism behind the hydrometeor charging and transport that produces charge separation and lightning discharges within thunderclouds [e.g. see chapter 3 in MacGorman and Rust, 1998]. Although cloud electrification and discharge processes are a complex function of the convective dynamics and microphysics of the cloud, the fundamental relationship between convection and electrification is easy to observe. For example, studies have shown that the strength of the convective process within a thundercell can be loosely parameterized (with large variance) by the intensity of the electrical activity within that cell as measured by the lightning flash rate. Williams [2001] has provided a review of experimental work that shows correlations between the total lightning flash rate and the fifth power of the radar cloud-top height (i.e. convective strength) of individual thunder cells. More recently, Ushio et al., [2001] used a large statistical sampling of optical data from the Lightning Imaging Sensor (LIS) in conjunction with data provided by the Precipitation Radar (PR) aboard the Tropical Rainfall Monitoring Mission (TRMM) satellite to conclude that the total lightning flash rate increases exponentially with storm height. Lightning activity levels have also been correlated to cloud ice content, a basic product of the convective process. For example, Blyth et al. [2001] used the Thermal Microwave Imager (TMI) aboard the TRMM satellite to observe a decrease in the 37 and 85 GHz brightness temperatures of upwelling terrestrial radiation during increased lightning activity. This reduction in brightness temperature is believed to be the result of increased ice scattering in the mixed phase region of the cloud. Toracinta and Zipser [2001] have found similar relationships using the Optical Transient Detector (OTD) satellite instrument and the Special Sensor Microwave Imager (SSM/I) aboard the DMSP satellites.

  3. Summer 2010 BOSTONIA 29 In summer 2007,

    E-print Network

    Goldberg, Bennett

    expensive. In August 1992, when Hurricane Andrew was spinning toward south Florida, most experts in the "cat the storms themselves. when clark's models put the potential damage of Hurricane Andrew at $13 billion

  4. Effects of explicit atmospheric convection at high CO2.

    PubMed

    Arnold, Nathan P; Branson, Mark; Burt, Melissa A; Abbot, Dorian S; Kuang, Zhiming; Randall, David A; Tziperman, Eli

    2014-07-29

    The effect of clouds on climate remains the largest uncertainty in climate change predictions, due to the inability of global climate models (GCMs) to resolve essential small-scale cloud and convection processes. We compare preindustrial and quadrupled CO2 simulations between a conventional GCM in which convection is parameterized and a "superparameterized" model in which convection is explicitly simulated with a cloud-permitting model in each grid cell. We find that the global responses of the two models to increased CO2 are broadly similar: both simulate ice-free Arctic summers, wintertime Arctic convection, and enhanced Madden-Julian oscillation (MJO) activity. Superparameterization produces significant differences at both CO2 levels, including greater Arctic cloud cover, further reduced sea ice area at high CO2, and a stronger increase with CO2 of the MJO. PMID:25024204

  5. Neural network prediction of a storm surge

    Microsoft Academic Search

    T.-L. Lee

    2006-01-01

    The occurrence of storm surge does not only destroy the resident's lives, but also cause the severe flooding in coastal areas. Therefore, accurate prediction of storm surge is an important task during the coming typhoon. Conventional numerical methods and experienced methods for storm surge prediction have been developed in the past, but it is still a complex ocean engineering problem

  6. Adaptive Online Scheduling in Storm Leonardo Aniello

    E-print Network

    Roma "La Sapienza", Università di

    Adaptive Online Scheduling in Storm Leonardo Aniello aniello@dis.uniroma1.it Roberto Baldoni success stories and catastrophic failures. In this scenario Storm, an open source distributed realtime com Twitter and Groupon. A Storm application is modeled as a topology, i.e. a graph where nodes are operators

  7. Atlantic Tropical Storm Tracking by Year

    NSDL National Science Digital Library

    Visitors to this site can access information on tropical storms and hurricanes in the Atlantic Ocean as far back as 1851. Information provided here includes a yearly map showing the tracks of all storms, and individual maps for each storm. The individual maps are accompanied by data tables that show latitude, longitude, wind speed, dates, and times.

  8. 2011 Baird Holm LLP Storm Water Management

    E-print Network

    Nebraska-Lincoln, University of

    © 2011 Baird Holm LLP Storm Water Management ­ Shifting Paradigms John P. Heil, Esq. Baird Holm LLP for control of storm water runoff has been the use of best management practices ("BMPs") ­ Notwithstanding limitations · Disaggregate storm water sources in computing waste load allocations · Assign waste load

  9. Deep Convective Clouds

    NSDL National Science Digital Library

    Convective clouds are clouds that develop vertically appearing like big stacks of clouds. One very common example is cumulonimbus clouds. Convective clouds are commonly connected to stormy weather. Monthly Cloud Coverage for Deep Convective Cloud data can be used to predict patterns in weather. The specific pattern associated with this data is tracking and predicting thunderstorms. In this lesson, the students will take a look at the Monthly Cloud Coverage for Deep Convective Cloud data, and name one month of the year 'Thunderstorm Season' for their continent.

  10. Author's personal copy Heavy air pollution suppresses summer thunderstorms

    E-print Network

    Li, Zhanqing

    Author's personal copy Heavy air pollution suppresses summer thunderstorms in central China Xin China, for assessing the impact of the increasing air pollution on convective precipitation. Adding frequency. This decrease was contributed by light and moderate (o25 mm dayÀ1 ) rainy days. These patterns

  11. Center for Turbulence Research Proceedings of the Summer Program 2012

    E-print Network

    Wang, Wei

    Center for Turbulence Research Proceedings of the Summer Program 2012 449 A mixed acoustic Helmholtz solver. A Dynamic Mode Decomposition is first applied to the Large Eddy Simulation (LES) database and convected down to the exit nozzle. The lowest purely acoustic mode being in the range 650-700 Hz

  12. Indian Summer

    SciTech Connect

    Galindo, E. [Sho-Ban High School, Fort Hall, ID (United States)

    1997-08-01

    This paper focuses on preserving and strengthening two resources culturally and socially important to the Shoshone-Bannock Indian Tribe on the Fort Hall Reservation in Idaho; their young people and the Pacific-Northwest Salmon. After learning that salmon were not returning in significant numbers to ancestral fishing waters at headwater spawning sites, tribal youth wanted to know why. As a result, the Indian Summer project was conceived to give Shoshone-Bannock High School students the opportunity to develop hands-on, workable solutions to improve future Indian fishing and help make the river healthy again. The project goals were to increase the number of fry introduced into the streams, teach the Shoshone-Bannock students how to use scientific methodologies, and get students, parents, community members, and Indian and non-Indian mentors excited about learning. The students chose an egg incubation experiment to help increase self-sustaining, natural production of steelhead trout, and formulated and carried out a three step plan to increase the hatch-rate of steelhead trout in Idaho waters. With the help of local companies, governmental agencies, scientists, and mentors students have been able to meet their project goals, and at the same time, have learned how to use scientific methods to solve real life problems, how to return what they have used to the water and land, and how to have fun and enjoy life while learning.

  13. Street Storm Water Conveyance Capacity

    Microsoft Academic Search

    James C. Y. Guo

    2000-01-01

    The street hydraulic capacity to convey storm water is dictated by the street gutter geometry and hydraulic characteristics. With the consideration of traffic safety, the street hydraulic conveyance capacity is also subject to a reduction defined by the water velocity and flow depth in the street gutter. In this study, the street hydraulic equa- tion is re-arranged to demonstrate that

  14. Overwash induced by storm conditions

    E-print Network

    Park, Young Hyun

    2009-05-15

    of historical hurricanes data and March 1962 northeaster, Hurricanes Carla, Camille and Hugo were notorious for high surge and Hurricane Celia and Andrew were noted for high winds and Hurricane Beulah, Agnes and Floyd were recorded as extreme rainfall... ....................................................................................6 2.2. Tropical Storm and Hurricane Climatology and Parameters........................7 2.3. Overwash Processes .....................................................................................9 2.4. Impacts of Geological...

  15. Managing storm water at airports

    SciTech Connect

    Halm, M.J.

    1996-09-01

    Airports are active facilities with numerous on-going operations at their sites. The following operations may adversely affect the water quality of nearby aquatic environments: De-icing runways; de-icing taxiways; de-icing and anti-icing aircraft; aircraft maintenance; and salt de-icer application. Until the amendments to the Clean Water Act of 1972, referred to as the Water Quality Act of 1987, were passed by Congress, the majority of storm water discharges in the US were unregulated. The Water Quality Act of 1987 was promulgated as an effort to manage the pollution resulting from storm water runoff. Many industrial facilities, especially airports, were faced with complex problems in attempting to comply with these new federal regulations. National Pollution Discharge Elimination System (NPDES) permits for airports with more than 50,000 flight operations per year require periodic monitoring of receiving waters and storm sewer outfalls. The federal government has given states jurisdiction in issuing NPDES permits for storm water discharges. States may require composite or grab samples.

  16. Large charge moment change lightning on 31 May to 1 June 2013, including the El Reno tornadic storm

    NASA Astrophysics Data System (ADS)

    Lang, Timothy J.; Cummer, Steven A.; Petersen, Danyal; Flores-Rivera, Lizxandra; Lyons, Walter A.; MacGorman, Donald; Beasley, William

    2015-04-01

    On 31 May 2013, a line of severe tornadic thunderstorms (the El Reno event) developed during the local afternoon in central Oklahoma, USA. Within range of the Oklahoma Lightning Mapping Array, the evolution of the event can be separated into three distinct periods: an Early period (before 02:00 UTC on 1 June) when the storm consisted of discrete supercells, a Middle period (02:00-05:00 UTC) when the convection began merging into a linear feature and stratiform precipitation developed, and a Late period (after 05:00 UTC) featuring a mature mesoscale convective system (MCS). Each of these periods demonstrated distinct patterns in the large (>100 C km) charge moment change (CMC) lightning that was produced. During the Early period, large-CMC positive cloud-to-ground (+CG) lightning was produced in the convective cores of supercells. These flashes were small in area (typically <500 km2) and were commonly associated with a sloping midlevel positive charge region in the echo overhang on the storm's forward flank. The Middle period featured a population of larger +CMCs (>500 km2, >300 C km) in the developing stratiform, similar to typical sprite-parent lightning in MCSs. During the Late period, convective large CMC +CGs ceased and instead large-CMC negative CGs were produced in and near the MCS convection. These flashes neutralized charge both in convection as well as in adjacent stratiform and anvil precipitation. The results suggest that the CMC metric has potential applications for studying tropospheric weather.

  17. Slithering into Summer

    ERIC Educational Resources Information Center

    Scott, Catherine; Matthews, Catherine

    2012-01-01

    The summer provides a unique opportunity for children to further their interests in science, especially science in the out-of-doors. Once school is out for the summer, there is seemingly unlimited time, with no strict curriculum guidelines to follow. For students with a passion for the out-of-doors, summer science camps and school-based summer

  18. Summer Studies CALENDAR 2010

    E-print Network

    Fabry, Frederic

    Summer Studies UNIVERSITY CALENDAR 2010 #12;McGill University, 2010 Summer Studies 1 ABOUT About This Calendar Published by: McGill Summer Studies McGill University 688 Sherbrooke Street West, Suite 1029, and changes can be made after this Calendar is published. Please check the Summer Studies website at www

  19. CUSP Summer Enhancement FellowshipPracticum & Research Assistantship Summer 2013 Application CUSP SUMMER ENHANCEMENT FELLOWSHIP

    E-print Network

    Hone, James

    CUSP Summer Enhancement Fellowship­Practicum & Research Assistantship Summer 2013 Application 1 CUSP SUMMER ENHANCEMENT FELLOWSHIP FOR PRACTICUMS & RESEARCH ASSISTANTSHIPS SUMMER 2013 APPLICATION The CUSP Summer Enhancement Fellowship for Practicums & Research Assistantships is a competitive grant

  20. CO2 isotopes as tracers of firn air diffusion and age in an Arctic ice cap with summer melting, Devon Island, Canada

    E-print Network

    Chappellaz, Jérôme

    CO2 isotopes as tracers of firn air diffusion and age in an Arctic ice cap with summer melting and the effects of summer melting. The 14 CO2 profile from the permeable firn includes the 1963 thermonuclear peak no indication of alteration by summer melting, which is attributed to a high degree of convective and diffusive

  1. 8, 39614000, 2008 Convection,

    E-print Network

    Paris-Sud XI, Université de

    ACPD 8, 3961­4000, 2008 Convection, extratropical mixing, in-situ freeze-drying in the TTL W. G of convection, extratropical mixing, and in-situ freeze-drying in the tropical tropopause layer W. G. Read 1 , M mixing, in-situ freeze-drying in the TTL W. G. Read et al. Title Page Abstract Introduction Conclusions

  2. Convective Cloud Systems

    NSDL National Science Digital Library

    The transfer of energy between Earth's surface and the atmosphere causes all weather. Energy can be transferred through three main processes: convection, conduction, and radiation. This video explains the differences between tropical convective cloud systems formed over land and those formed over oceans. The segment is one minute nine seconds in length. A background essay and discussion questions are included.

  3. Interacting Convection Zones

    E-print Network

    L. J. Silvers; M. R. E. Proctor

    2007-08-28

    We present results from simulations to examine how the separation between two convectively unstable layers affect their interaction. We show that two convectively unstable layers remain connected via the overshooting plumes even when they are separated by several pressure scale heights.

  4. Electrification of particles in dust storms: Field measurements during the monsoon period in Niger

    NASA Astrophysics Data System (ADS)

    Sow, Mamadou; Crase, Emmanuel; Rajot, Jean Louis; Sankaran, R. Mohan; Lacks, Daniel J.

    2011-11-01

    On the first fortnight of June 2010, experiments were carried out at a millet field in Niger to address the electrification of soil particles under natural conditions. The experiments were conducted during a period of high wind erosion, resulting from the passage of mesoscale convective systems (MCSs) which generate “walls” of dust passing through the Sahel. Soil particles are lifted from the ground by the stress exerted by the wind, with a threshold for emission that is particle size dependent. These particles then collide with other particles, leading to electrostatic charging of the particles. Soil samples of either positive or negative polarity were collected from the soil surface in 3 situations: 1) during “quiet” periods (far removed from a dust storm), 2) immediately after a dust storm, and 3) 12 h after a dust storm. Our results show that immediately after a dust storm, smaller particles are predominantly charged positive and larger particles are predominantly charged negative; this effect is still evident but smaller in magnitude 12 h after a dust storm. This size dependence for the charge polarity is in apparent contradiction with previous investigations; we believe this contradiction is only apparent, because the very fine particles, which we cannot measure with our technique, are expected to be negatively charged. Our results are rationalized by combining a population balance model for charged species trapped in high energy states with the wind threshold for soil particle motion.

  5. Relationship of intracloud lightning radiofrequency power to lightning storm height, as observed by the FORTE satellite

    NASA Astrophysics Data System (ADS)

    Jacobson, Abram R.

    2003-04-01

    Prior studies have noted a strongly nonlinear enhancement of lightning flash rates with increasing cloud height. Here we report a related observation, of a tendency for increasing intracloud-discharge radiofrequency-emission power for increased height of the electrified cloud. The FORTE satellite's radio-frequency-receiver payload has performed extensive recordings of electromagnetic emissions of lightning discharges. The most commonly occurring such emission arises from intracloud electrical breakdown and is usually recognizable by a pulse followed by a delayed echo from the ground reflection. We have used other systems of lightning monitors to provide source locations for an extended data set of FORTE intracloud-discharge signals. The interpulse separation within each pulse pair yields the discharge height above the reflective ground. The storm in which the pulse occurs usually provides many (at least 50) recorded events. From the pattern of these events' heights, we can usually infer a capping height, which serves as an upper bound on the lightning discharge heights for that storm. We find that there is a strong statistical increase of effective radiated power of intracloud discharges, for increasing capping height of the parent storm. Thus a future satellite-based lightning monitor that triggers on only the most intense radiofrequency emissions will be strongly selective for electrified storms with very deep vertical development. Such storms are also indicated in severe convective weather.

  6. Thyroid Storm Precipitated by Duodenal Ulcer Perforation

    PubMed Central

    Natsuda, Shoko; Nakashima, Yomi; Horie, Ichiro; Kawakami, Atsushi

    2015-01-01

    Thyroid storm is a rare and life-threatening complication of thyrotoxicosis that requires prompt treatment. Thyroid storm is also known to be associated with precipitating events. The simultaneous treatment of thyroid storm and its precipitant, when they are recognized, in a patient is recommended; otherwise such disorders, including thyroid storm, can exacerbate each other. Here we report the case of a thyroid storm patient (a 55-year-old Japanese male) complicated with a perforated duodenal ulcer. The patient was successfully treated with intensive treatment for thyroid storm and a prompt operation. Although it is believed that peptic ulcer rarely coexists with hyperthyroidism, among patients with thyroid storm, perforation of a peptic ulcer has been reported as one of the causes of fatal outcome. We determined that surgical intervention was required in this patient, reported despite ongoing severe thyrotoxicosis, and reported herein a successful outcome. PMID:25838951

  7. Dust storm monitoring: effects on the environment, human health, and potential security conflicts

    NASA Astrophysics Data System (ADS)

    Davara, Fernando; de la Cruz, Antonio

    2004-10-01

    Monitoring dust storms with recently available medium and moderate resolution satellites (Meris, Modis and SeaWiFS) is providing new global information regarding the sources, transportation tracks and affected areas. Saharan dust plumes reach the SE region of the United States and the Caribbean region in summer and the Amazon basin in winter. Generally these Saharan plumes branch off in dust tracks along the North Atlantic reaching Western Europe as far north as the Scandinavian countries. Furthermore, dust storms originating in the Eastern Sahara and Northern African deserts form dust plumes propagated by the Sirocco winds that, after crossing the Mediterranean Sea, affect Southern and Central Europe particularly during spring and summer. Dust storms originating in the Gobi and Taklamakan deserts blow in an easterly direction propagating dust plumes affecting Korea, Japan and reach the United States after crossing the Pacific Ocean. The large amount of cyclic deposition generated by dust storms produces an environmental impact that causes the decay of coral reefs in the Caribbean, the origin and distribution of red tides and the disappearance of sea grasses. The relationship of dust plumes with the increasing number of asthma and allergy cases in the Caribbean correlates well with the appearance of similar cases in Europe and elsewhere during the mid 1980s. The recurrence presence of insecticides in regions where these products were banned long ago, or where they were never used, may be partly due to Saharan dust plumes. The loss of agricultural soil, literally blown away by dust storms in the source areas, creates hardship, hunger and forced-migration. Dust storms should be considered as an important security issue.

  8. Solute Sources in Stream Water during Consecutive Fall Storms in a Northern Hardwood Forest Watershed: A Combined Hydrological, Chemical and Isotopic Approach

    Microsoft Academic Search

    M. J. Mitchell; K. B. Piatek; S. Christopher; B. Mayer; C. Kendall; P. Mchale

    2006-01-01

    Understanding the effects of climate change including precipitation patterns has important implications for evaluating the\\u000a biogeochemical responses of watersheds. We focused on four storms in late summer and early fall that occurred after an exceptionally\\u000a dry period in 2002. We analyzed not only the influence of these storms on episodic chemistry and the role of different water\\u000a sources in affecting

  9. Variations in spectroscopic characteristics and disinfection byproduct formation potentials of dissolved organic matter for two contrasting storm events

    NASA Astrophysics Data System (ADS)

    Nguyen, Hang Vo-Minh; Lee, Mi-Hee; Hur, Jin; Schlautman, Mark A.

    2013-02-01

    SummaryChanges in disinfection byproduct (DBP) precursors during storm events have not been intensively studied to date despite their dramatic impact on downstream drinking water supplies. For this study, variations in dissolved organic matter (DOM) spectroscopic properties and DBP formation potentials (DBPFPs), and the correlations among these various parameters, were investigated in river water samples collected under two contrasting storm event conditions (a strong summer storm versus a weak fall event). Fluorescence excitation-emission matrices (EEMs) combined with parallel factor analysis revealed that a combination of two humic-like components (C1 and C2) dominated the EEM data of the storm samples. Measured DOM characteristics and DBPFPs varied over a wider range during the more intense summer storm, exhibiting higher values of specific ultraviolet absorbance and C1/C2 ratio at high flow conditions. Variations in the fluorescence index were less pronounced during the two storm events. The spectroscopic changes were well explained by the input of terrestrial DOM sources from the surrounding catchments during the storms. Different trends of the formation potentials for trihalomethanes and haloacetic acids on the recession limb of the hydrographs suggest that the structures responsible for DBP precursors during storm events may not be the same for the two classes of DBPs. The ultraviolet light-absorbing moieties in DOM appear to play major roles in generating DBPs, as evidenced by their strong positive correlations with DBPFPs. Higher correlations with DBPFP for C1 versus C2 suggest that humic-like substances associated with more aromatic and condensed structures have a greater proclivity to generate DBP upon chlorination.

  10. VHF radar observations of mesospheric density distrubance caused by Typhoon Susan and tropical storms in the western Pacific area

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Tsao, Y. D.; Johnson, D. L.; Chen, A. J.; Lin, C. H.

    1989-01-01

    The atmospheric parameters from the toposphere to the middle atmosphere during Typhoon Susan and tropical storms in May and June 1988 were observed by VHF radar in Taiwan. Time-dependent wind velocities with three-dimensional profiles are plotted by processing the backscattered echo power data and the Doppler spectral width of the signal returns from the VHF radar. The propagation characteristics of the gravity waves excited by the enhanced convection motions of the storms and the density perturbations caused by this gravity wave progagation are determined.

  11. Development of a severe local storm prediction system: A 60-day test of a mesoscale primitive equation model

    NASA Technical Reports Server (NTRS)

    Paine, D. A.; Zack, J. W.; Kaplan, M. L.

    1979-01-01

    The progress and problems associated with the dynamical forecast system which was developed to predict severe storms are examined. The meteorological problem of severe convective storm forecasting is reviewed. The cascade hypothesis which forms the theoretical core of the nested grid dynamical numerical modelling system is described. The dynamical and numerical structure of the model used during the 1978 test period is presented and a preliminary description of a proposed multigrid system for future experiments and tests is provided. Six cases from the spring of 1978 are discussed to illustrate the model's performance and its problems. Potential solutions to the problems are examined.

  12. Structure of the Highly Sheared Tropical Storm Chantal During CAMEX -4

    NASA Technical Reports Server (NTRS)

    Heymsfield, Gerald M.; Halverson, J.; Black, M.; Marks, F.; Zipser, E.; Tian, L.; Belcher, L.; Bui, P.; Im, E.; Starr, David OC. (Technical Monitor)

    2002-01-01

    On 20 August 2001 during the Convection and Moisture Experiment 4 (CAMEX-4) and NOAA Hurricane Field Program (HFP2001), the NASA high-altitude ER-2 and medium-altitude DC-8, and lower-altitude NOAA P3 aircraft conducted a coordinated Quantitative Precipitation Estimation (QPE) mission focused on convection in Tropical Storm Chantal. This storm first became a depression on 14 August, a tropical storm on 17 August, and it maintained maximum winds of about 65-70 mph during 19-20 August with minimum pressures ranging from 1008 mb on 19 August to 1001 mb late on 20 August. The storm was westward moving and was forecasted to intensify and landfall near the Yucatan-Belize border late on 20 August. Chanter failed to intensify and instead exhibited a highly sheared structure with an open low-level circulation and intense convection well to the northeast of this circulation center. The NASA ER-2 and DC-8 aircraft were closely coordinated with the NOAA P3 (NOAA-42). The NASA aircraft collected remote sensing and in situ data sets, while the P3 collected lower level in situ and radar data; both the DC-8 and P3 released 7 and 24 dropsondes, respectively. These aircraft measurements provided a unique opportunity to examine the structure of a sheared system and why it did not develop as forecasted a few days earlier. This paper will describe a preliminary study of the precipitation and wind structure provided by the NASA aircraft within the context of the NOAA P3 measurements.

  13. Direct Measurements of the Convective Recycling of the Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Bertram, Timothy H.; Perring, Anne E.; Wooldridge, Paul J.; Crounse, John D.; Kwan, Alan J.; Wennberg, Paul O.; Scheuer, Eric; Dibb, Jack; Avery, Melody; Sachse, Glen; Vay, Stephanie A.; Crawford, James H.; McNaughton, Cameron S.; Clarke, Antony; Pickering, Kenneth E.; Fuelberg, Henry; Huey, Greg; Blake, Donald R.; Singh, Hanwant B.; Hall, Samuel R.; Shetter, Richard E.; Fried, Alan; Heikes, Brian G.; Cohen, Ronald C.

    2007-01-01

    We present a statistical representation of the aggregate effects of deep convection on the chemistry and dynamics of the Upper Troposphere (UT) based on direct aircraft observations of the chemical composition of the UT over the Eastern United States and Canada during summer. These measurements provide new and unique observational constraints on the chemistry occurring downwind of convection and the rate at which air in the UT is recycled, previously only the province of model analyses. These results provide quantitative measures that can be used to evaluate global climate and chemistry models.

  14. Dust storm off Western Africa

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The impacts of Saharan dust storms reach far beyond Africa. Wind-swept deserts spill airborne dust particles out over the Atlantic Ocean where they can enter trade winds bound for Central and North America and the Caribbean. This Moderate Resolution Imaging Spectroradiometer (MODIS) image shows a dust storm casting an opaque cloud of cloud across the Canary Islands and the Atlantic Ocean west of Africa on June 30, 2002. In general it takes between 5 and 7 days for such an event to cross the Atlantic. The dust has been shown to introduce foreign bacteria and fungi that have damaged reef ecosystems and have even been hypothesized as a cause of increasing occurrences of respiratory complaints in places like Florida, where the amount of Saharan dust reaching the state has been increasing over the past 25 years.

  15. The relative influence of aerosols and the environment on organized tropical and midlatitude deep convection

    NASA Astrophysics Data System (ADS)

    Grant, Leah Danielle

    In this two-part study, the relative impacts of aerosols and the environment on organized deep convection, including tropical sea-breeze convection and midlatitude supercellular and multicellular deep convection, are investigated within idealized cloud-resolving modeling simulations using the Regional Atmospheric Modeling System (RAMS). Part one explores aerosol-cloud-land surface interactions within tropical deep convection organized along a sea breeze front. The idealized RAMS domain setup is representative of the coastal Cameroon rainforest in equatorial Africa. In order to assess the potential sensitivity of sea-breeze convection to increasing anthropogenic activity and deforestation occurring in such regions, 27 total simulations are performed in which combinations of enhanced aerosol concentrations, reduced surface roughness length, and reduced soil moisture are included. Both enhanced aerosols and reduced soil moisture are found to individually reduce the precipitation due to reductions in downwelling shortwave radiation and surface latent heat fluxes, respectively, while perturbations to the roughness length do not have a large impact on the precipitation. The largest soil moisture perturbations dominate the precipitation changes due to reduced low-level moisture available to the convection, but if the soil moisture perturbation is moderate, synergistic interactions between soil moisture and aerosols enhance the sea breeze precipitation. This is found to result from evening convection that forms ahead of the sea breeze only when both effects are present. Interactions between the resulting gust fronts and the sea breeze front locally enhance convergence and therefore the rainfall. Part two of this study investigates the relative roles of midlevel dryness and aerosols on supercellular and multicellular convective morphology. A common storm-splitting situation is simulated wherein the right-moving storm becomes a dominant supercell and the left-moving storm evolves into a multicellular cluster. The right-mover, which is a classic (CL) supercell in the control simulation, becomes a low-precipitation (LP) supercell with increasing dryness aloft. Different midlevel hail growth mechanisms are found to dominate in the CL and LPs that assist in explaining their varying surface precipitation distributions. Although the CL and LP supercells are dynamically similar, their microphysical structure differs due to the strong control that midlevel dryness exerts on supercell morphology; aerosols have little impact on the supercellular structure. On the other hand, while midlevel dryness also dominates the changes to the multicellular convection, aerosols influence the precipitation through feedbacks to the cold pool strength and subsequent dynamical forcing. Overall, aerosol impacts are largest for the most weakly organized convection (tropical sea breeze convection) and smallest for strongly dynamic convection (supercells). Additionally, aerosol impacts are modulated by environmental influences, most notably soil moisture availability and midlevel moisture content in this study.

  16. What Causes a Solar Storm?

    NSDL National Science Digital Library

    This is a tri-fold brochure about the solar storms known as coronal mass ejections. The text in this brochure addresses such topics as what a coronal mass ejection, or CME, is, how the Sun produces CMEs, how a CME behaves, when they happen and how we see them, and how CMEs affect Earth. Additional information is included about the SOHO spacecraft, which images CMEs, and web links to find more information.

  17. Multiscale storm identification and forecast

    Microsoft Academic Search

    V Lakshmanan; R. Rabin; V. DeBrunner

    2003-01-01

    We describe a recently developed hierarchical K-Means clustering method for weather images that can be employed to identify storms at different scales. We describe an error-minimization technique to identify movement between successive frames of a sequence and we show that we can use the K-Means clusters as the minimization template. A Kalman filter is used to provide smooth estimates of

  18. Storm surges: perspectives and options

    Microsoft Academic Search

    Hans von Storch; Katja Woth

    2008-01-01

    This review paper attempts to summarize the scattered and fragmented knowledge about past and possible future changing storm-surge\\u000a statistics using the particularly well-studied case of the North Sea as an example. For this region, a complete and robust\\u000a analysis methodology has been developed in recent years. This methodology is based on dynamical and statistical models. Using\\u000a the concept of dynamical

  19. Magnetic Storms from the Ground

    NSDL National Science Digital Library

    2012-08-03

    This is an activity about the detection of magnetic storms. Learners will plot the locations of magnetic observatories in Canada and analyze the magnetic intensity for each station, looking for the difference between stable magnetic activity and the largest difference in change in magnetic activity and identifying any patterns of change. This is the thirteenth activity in the Exploring the Earth's Magnetic Field: An IMAGE Satellite Guide to the Magnetosphere educators guide.

  20. Observations of ionospheric convection from the Wallops SuperDARN radar at middle latitudes

    NASA Astrophysics Data System (ADS)

    Baker, J. B. H.; Greenwald, R. A.; Ruohoniemi, J. M.; Oksavik, K.; Gjerloev, J. W.; Paxton, L. J.; Hairston, M. R.

    2007-01-01

    During geomagnetic storms the ability of the Super Dual Auroral Radar Network (SuperDARN) to measure ionospheric convection becomes limited when the radars suffer from absorption and the auroral disturbance expands equatorward of the radar sites. To overcome these shortcomings, it was decided to construct a SuperDARN radar at middle latitudes on the grounds of the NASA Wallops Flight Facility. This paper presents the first comprehensive analysis of Doppler measurements from the Wallops radar, which commenced operations in May 2005. Wallops measurements are compared with the Goose Bay radar during the onset of a geomagnetic storm on 31 August 2005: Goose Bay measured the onset of geomagnetic activity at high latitude while Wallops monitored the expansion of convection to middle latitudes. Average convection patterns binned by the Kp geomagnetic index are also presented. During weak-moderate geomagnetic activity (Kp ? 3) the Wallops radar observes ionospheric irregularities between 50° and 60° magnetic latitude drifting westward across much of the nightside. When these measurements are incorporated into the calculation of an average SuperDARN convection pattern, the streamlines of polar cap outflow on the nightside become kinked in a manner reminiscent of the Harang discontinuity. This morphology arises quite naturally when the two-cell convection at high latitudes merges with the prevailing westward convection at middle latitudes. During increased geomagnetic activity (Kp ? 3), Wallops is able to measure the expansion of auroral electric fields to middle latitudes and the average SuperDARN cross-polar cap potential is increased by 25%.

  1. Magneto-convection.

    PubMed

    Stein, Robert F

    2012-07-13

    Convection is the transport of energy by bulk mass motions. Magnetic fields alter convection via the Lorentz force, while convection moves the fields via the curl(v×B) term in the induction equation. Recent ground-based and satellite telescopes have increased our knowledge of the solar magnetic fields on a wide range of spatial and temporal scales. Magneto-convection modelling has also greatly improved recently as computers become more powerful. Three-dimensional simulations with radiative transfer and non-ideal equations of state are being performed. Flux emergence from the convection zone through the visible surface (and into the chromosphere and corona) has been modelled. Local, convectively driven dynamo action has been studied. The alteration in the appearance of granules and the formation of pores and sunspots has been investigated. Magneto-convection calculations have improved our ability to interpret solar observations, especially the inversion of Stokes spectra to obtain the magnetic field and the use of helioseismology to determine the subsurface structure of the Sun. PMID:22665893

  2. Saturn's Great White Storm (2010): Correlations between Clouds and Thermal Fields?

    NASA Astrophysics Data System (ADS)

    Momary, T.; Yanamandra-Fisher, P. A.; Orton, G. S.; Baines, K. H.; Fletcher, L.; Trinh, S.; Delcroix, M.

    2011-12-01

    It is well known that convective storms occur regularly in Saturn's atmosphere, but giant storm outbreaks, known as Great White Spot (GWS) outbreaks, occur approximately every 29 years or once per Saturnian year, just past northern solstice. Including the recent GWS outbreak of December 2010, a total of six have occurred, and are considered to be related to the changing seasonal insolation, though their triggers are not yet known or what occurs below the clouds on smaller temporal and spatial timelines. Although not predictable, as evidenced by the current Northern Storm and observed by Cassini, the great storms start out with a violent outbreak, dredging up material from the deep atmosphere, which then is dispersed by the prevailing winds. The recent 2010 December GWS outbreak is an outlier, occurring at northern latitudes of approximately 35°N (the northern "Tornado Alley"), just past vernal equinox, almost a season early. It has rapidly encircled the planet in two months and is now in its mature phase, with discrete structure obvious at all longitudes at both mid-infrared and deep atmosphere (or 5-microns). Recent amateur observations indicate a link between lightning strikes, convective storm activity, GWS and spoke activity in the morning ansa (Delacroix et al., 2011). We shall explore correlations between the many visible/CCD observations from the amateur community, the albedo and thermal maps produced with data acquired from NASA/InfraRed Telescope Facility (IRTF)/NSFCAM2, a 1 - 5-micron imager, during the various phases of the 2010 - 2011 GWS. We will characterize changes in the local environs of the outbreak site at various epochs and compare with other locations on the planet. Delacroix, M., E. Kraaikamp and P. Yanamandra-Fisher,2011. First Ground Observations of Saturn's Spokes Around 2009 Equinox. EPSC/DPS, Nantes, France.

  3. Dust Storm in Southern California

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Along historic Route 66, just southeast of the little town of Amboy, California, lies a dried-up lake. Dry lakebeds are good sources of two things: salt and dust. In this image, the now-parched Bristol Lake offers up both. On April 12, 2007, dust storms menaced the area around Amboy. To the northwest, near Newberry Springs, California, dust hampered visibility and led to a multi-car collision on Interstate 40, killing two people and injuring several others. The same day, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of a dust storm in the dry remains of Bristol Lake. Many small dust clouds boil up from the ground surface, casting their shadows to the northwest. A bright white cloud floating over the dust also throws its shadow onto the ground below. East of the dust storm are salt works that stand out from the surrounding landscape thanks to their straight lines and sharp angles. Dark ground surfaces alternate with mined white salt in a network of stripes. When lakes evaporate, chemicals that had been dissolved in the water stay behind, making dry lake beds an ideal place to find heavy concentrations of minerals, including salt. Besides the salt works, something else appears in stark contrast to this arid place. Lush green fields of irrigated crops appear in the east. Besides their color, their orderly arrangement reveals their human-made origin.

  4. Biological solution to storm water?

    PubMed

    Bixio, D; Thoeye, C; De Gueldre, G

    2004-01-01

    Standard practice in Flanders is to limit the hydraulic capacity of sewage treatment works to 6Q14 (Q14= 1.7 dry weather flow Q(DWF)). A maximum of 3Q14 is treated biologically, while the excess flow undergoes only physical treatment in storm tanks. This practice has been challenged by a new high-flow activated sludge operation concept, consisting of the treatment of the full storm sewage flow in the biological train and of the use of the storm tanks as additional secondary clarifiers. After successful testing in two installations, 56 works of different sizes and types were switched to high-flow activated sludge operation from 1999 to 2002. This paper reports on progress and experiences gained since then. The analysis focuses on the parameters subject to regulatory discharge (BOD, COD, suspended solids, total nitrogen and total phosphorus) plus ammonia. Special attention is paid to the performance of the clarification and of the nitrification processes. The results indicate that high-flow biological treatment provides a substantial reduction in wet weather discharges while maintaining acceptable process operating conditions. PMID:15553473

  5. Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. 138: 596611, April 2012 A Tropical transition of a Mediterranean storm by jet crossing

    E-print Network

    Chaboureau, Jean-Pierre

    2012 A Tropical transition of a Mediterranean storm by jet crossing Jean-Pierre Chaboureau,a * Florian to the initial conditions. Reduced static stability at the southern tip of the upper-level trough determined vertically developed convection was further enhanced by the jet-induced upward forcing. Otherwise

  6. Characterizing storm-event nitrate fluxes in a fifth order suburbanizing watershed using in situ sensors.

    PubMed

    Carey, Richard O; Wollheim, Wilfred M; Mulukutla, Gopal K; Mineau, Madeleine M

    2014-07-15

    Land use influences the distribution of nonpoint nitrogen (N) sources in urbanizing watersheds and storm events interact with these heterogeneous sources to expedite N transport to aquatic systems. In situ sensors provide high frequency and continuous measurements that may reflect storm-event N variability more accurately compared to grab samples. We deployed sensors from April to December 2011 in a suburbanizing watershed (479 km2) to characterize storm-event nitrate-N (NO3-N) and conductivity variability. NO3-N concentrations exhibited complex patterns both within and across storms and shifted from overall dilution (source limitation) before summer baseflows to subsequent periods of flushing (transport limitation). In contrast, conductivity generally diluted with increasing runoff. Despite diluted NO3-N concentrations, NO3-N fluxes consistently increased with flow. Sensor flux estimates for the entire deployment period were similar to estimates derived from weekly and monthly grab samples. However, significant differences in flux occurred at monthly time scales, which may have important implications for understanding impacts to temporally sensitive receiving waters. Evidence of both supply (nutrient-poor) and transport (nutrient-rich) limitation patterns during storms is consistent with watersheds undergoing land use transitions. Tracking shifts in these patterns could indicate N accumulation in developing watersheds and help identify mitigation opportunities prior to N impairment. PMID:24945442

  7. Numerical Simulations of the Ring Current During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Chen, M. W.; Lemon, C.; Guild, T. B.; Schulz, M.; Roeder, J. L.; Lui, A.; Keesee, A. M.; Goldstein, J.; Le, G.; Rodriguez, J. V.

    2012-12-01

    Recent progress in ring current modeling has shown the importance of a self-consistent treatment of particle transport along with magnetic and electric fields in the inner magnetosphere. The ring current intensity and spatial distribution are significantly affected by variations in the plasma sheet (the major source to the ring current), the cross polar cap potential, and compressions and expansions of the magnetosphere. We simulate the ion and electron ring current and plasma sheet by using the magnetically and electrically self-consistent Rice Convection Model-Equilibrium [Lemon et al., JGR, 2004] with a time-varying magnetopause driven by upstream solar wind and interplanetary magnetic (IMF) conditions and with time-varying plasma sheet distributions as boundary conditions. Examples of detailed comparisons of simulated storm events with in-situ magnetic intensities (e. g., GOES, Polar/MPA, or THEMIS) and proton flux spectra (e. g., LANL/MPA and SOPA, Polar/CAMMICE, or THEMIS) and energetic neutral atom (ENA) fluxes (e. g., TWINS) will be shown. We will also present comparisons of observed electron flux spectra with simulations based on a few simple electron loss models. These data-model comparisons test the ability of our model to characterize the ring current environment and the storm-time inner magnetospheric magnetic field.

  8. CO Signatures in Subtropical Convective Clouds and Anvils During CRYSTAL-FACE: An Analysis of Convective Transport and Entertainment Using Observations and a Cloud-Resolving Model

    NASA Technical Reports Server (NTRS)

    Lopez, Jimena P.; Fridlind, Ann M.; Jost, Hans-Jurg; Loewenstein, Max; Ackerman, Andrew S.; Campos, Teresa L.; Weinstock, Elliot M.; Sayres, David S.; Smith, Jessica B.; Pittman, Jasna V.; Hallar, A. Gannet; Avallone, Linnea M.; Davis, Sean M.; Herman, Robert L.

    2006-01-01

    Convective systems are an important mechanism in the transport of boundary layer air into the upper troposphere. The Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) campaign, in July 2002, was developed as a comprehensive atmospheric mission to improve knowledge of subtropical cirrus systems and their roles in regional and global climate. In situ measurements of carbon monoxide (CO), water vapor (H20v), and total water (H20t) aboard NASA's . WB-57F aircraft and CO aboard the U.S. Navy's Twin Otter aircraft were obtained to study the role of convective transport. Three flights sampled convective outflow on 11, 16 and 29 July found varying degrees of CO enhancement relative to the fiee troposphere. A cloud-resolving model used the in situ observations and meteorological fields to study these three systems. Several methods of filtering the observations were devised here using ice water content, relative humidity with respect to ice, and particle number concentration as a means to statistically sample the model results to represent the flight tracks. A weighted histogram based on ice water content observations was then used to sample the simulations for the three flights. In addition, because the observations occurred in the convective outflow cirrus and not in the storm cores, the model was used to estimate the maximum CO within the convective systems. In general, anvil-level air parcels contained an estimated 20-40% boundary layer air in the analyzed storms.

  9. CO Signatures in Subtropical Convective Clouds and Anvils during CRYSTAL-FACE: An Analysis of Convective Transport and Entrainment using Observations and a Cloud-Resolving Model

    NASA Technical Reports Server (NTRS)

    Lopez, Jimena P.; Fridlind, Ann M.; Jost, Hans-Juerg; Loewenstein, Max; Ackerman, Andrew S.; Campos, Teresa L.; Weinstock, Elliot M.; Sayres, David S.; Smith, Jessica B.; Pittman, Jasna V.

    2006-01-01

    Convective systems are an important mechanism in the transport of boundary layer air into the upper troposphere. The Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) campaign, in July 2002, was developed as a comprehensive atmospheric mission to improve knowledge of subtropical cirrus systems and their roles in regional and global climate. In situ measurements of carbon monoxide (CO), water vapor (H2Ov), and total water (H2Ot) aboard NASA's WB-57F aircraft and CO aboard the U.S. Navy's Twin Otter aircraft were obtained to study the role of convective transport. Three flights sampled convective outflow on 11, 16 and 29 July found varying degrees of CO enhancement relative to the free troposphere. A cloud-resolving model used the in situ observations and meteorological fields to study these three systems. Several methods of filtering the observations were devised here using ice water content, relative humidity with respect to ice, and particle number concentration as a means to statistically sample the model results to represent the flight tracks. A weighted histogram based on ice water content observations was then used to sample the simulations for the three flights. In addition, because the observations occurred in the convective outflow cirrus and not in the storm cores, the model was used to estimate the maximum CO within the convective systems. In general, anvil-level air parcels contained an estimated 20-40% boundary layer air in the analyzed storms.

  10. The News, Summer 1999-Summer 2000.

    ERIC Educational Resources Information Center

    Robertson, Trische, Ed.

    2000-01-01

    This document contains five quarterly issues of The News, published Summer 1999 through Summer 2000 by the Community College League of California. The following items are contained in this document: "Grant Writing Success Depends on Resources, Information and Staff,""College Theaters Perform Balancing Act with Community, Instruction,…

  11. Summer Curriculum Enhancement Fellowship

    E-print Network

    Zhou, Yaoqi

    Summer Curriculum Enhancement Fellowship Guidelines and Application;[SUMMER CURRICULUM ENHANCEMENT FELLOWSHIP] February 2013 IU School of Informatics and Computing at IUPUI www.informatics.iupui.edu Curriculum Enhancement Fellowship IU

  12. The Summer Vision Project

    E-print Network

    Papert, Seymour

    1966-07-01

    The summer vision project is an attempt to use our summer workers effectively in the construction of a significant part of a visual system. The particular task was chosen partly because it can be segmented into sub-problems ...

  13. Effects of Season and Solar Cycle on Storm-Time Behavior of the Generalized Polar Wind

    NASA Astrophysics Data System (ADS)

    Barakat, A. R.; Schunk, R. W.

    2011-12-01

    We studied the effects of a geomagnetic storm on the behavior of the polar wind for different seasonal and solar activity conditions using a generalized polar wind model that extends up to 8 RE, with a fluid-like component at low altitudes and a macroscopic PIC component at high altitudes. The geomagnetic activity was represented by an idealized storm followed by a quiet period of roughly equal time intervals. Four runs were performed for different combinations of summer/winter and solar maximum/minimum in order to elucidate the combined effect of a storm with seasonal and solar activity. Comparing the results for the storm and quiet periods, and for the four cases mentioned above, we concluded the following: (1) During the main phase, the storm effects was shown most prominently as large increases of O+/H+ density ratio, n(O+)/n(H+), O+/H+ flux ratio, F(O+)/F(H+), and in the O+ flux, F(O+). (2) During the storm main phase, the H+ flux is decreased, which is consistent with the "blowout" phenomenon mentioned in previous literature. (3) The O+ flux can reach up to 1010 cm-2 s-1 during the main phase, for the case of summer/solar maximum. (4) For the case of summer/solar maximum, F(O+) is comparable to, or larger than, F(H+) everywhere, while F(O+) is less than F(H+) almost everywhere (except the main phase) for the case of winter/solar minimum. (5) In agreement with observations, O+ flows upwards (V(O+) > 0) everywhere above 5,000 km. (6) At intermediate altitudes (few RE), the O+/H+ drift velocity ratio V(O+)/V(H+) is larger within the polar cap than within the cusp/auroral region due to the contact potential associated with the polar rain. (7) Drift velocities, V(O+) and V(H+) at high altitudes are not sensitive to season or solar activity because they are mainly controlled by the magnetospheric hot electrons and the wave-particle interactions (WPI) which are mostly independent of those conditions. (8) For solar maximum, n(O+) and F(O+) are higher, while n(H+) and F(H+) are lower than for solar minimum. (9) In summer, n(O+) and F(O+) are higher than in winter, while n(H+) and F(H+) are relatively insensitive to seasonal effects.

  14. Organizational modes of squall-type Mesoscale Convective Systems during premonsoon season over eastern India

    NASA Astrophysics Data System (ADS)

    Dalal, Shubho; Lohar, Debasish; Sarkar, Sumana; Sadhukhan, Indrajit; Debnath, Gokul Chandra

    2012-03-01

    Premonsoon thunderstorms, locally known as Nor'westers, were studied over the eastern part of India using routine observations and data acquired from STORM (Severe Thunderstorm Observation and Regional Modelling) program during the premonsoon season, i.e., March through May, of 2006-08. Doppler radar image analysis reveals that premonsoon convective activities on many occasions may be described as squall-type linear Mesoscale Convective Systems (MCSs) which are composed of three common organizational modes viz. Trailing Stratiform (TS), Leading Stratiform (LS) and Parallel Stratiform (PS). The most dominant and common mode of organization, in terms of frequency of occurrences, duration, mean speed and inter-conversion among the different modes, is the TS, contributing about 65% of the cases while LS and PS contribute only about 15% and 20% respectively. Examination of pre-storm environments indicates that line-perpendicular and line-parallel storm-relative winds possibly determine the modes of organization. Case studies, one from each class, were also carried out and the observed structures were found to be similar to that observed in warmer mid-latitudes with certain exceptions. Unlike mid-latitude MCSs, convective cells during the premonsoon season initiate over the region with the support of weak synoptic setting and in course of time, organize themselves to become an MCS under favorable mesoscale convective environment. However they are short-lived irrespective of the modes of organization.

  15. The Effects of Aerosols on Intense Convective Precipitation in the Northeastern U.S.

    SciTech Connect

    Ntelekos, Alexandros A.; Smith, James S.; Donner, Leo J.; Fast, Jerome D.; Gustafson, William I.; Chapman, Elaine G.; Krajewski, Witold F.

    2009-08-03

    A fully coupled meteorology-chemistry-aerosol mesoscale model (WRF-Chem) is used to assess the effects of aerosols on intense convective precipitation over the northeastern United States. Numerical experiments are performed for three intense convective storm days and for two scenarios representing “typical” and “low” aerosol conditions. The results of the simulations suggest that increasing concentrations of aerosols can lead to either enhancement or suppression of precipitation. Quantification of the aerosol effect is sensitive to the metric used due to a shift of rainfall accumulation distribution when realistic aerosol concentrations are included in the simulations. Maximum rainfall accumulation amounts and areas with rainfall accumulations exceeding specified thresholds provide robust metrics of the aerosol effect on convective precipitation. Storms developing over areas with medium to low aerosol concentrations showed a suppression effect on rainfall independent of the meteorologic environment. Storms developing in areas of relatively high particulate concentrations showed enhancement of rainfall when there were simultaneous high values of CAPE, relative humidity and wind shear. In these cases, elevated aerosol concentrations resulted in stronger updrafts and downdrafts and more coherent organization of convection. For the extreme case, maximum rainfall accumulation differences exceeded 40 mm. The modeling results suggest that areas of the northeastern U.S. urban corridor that are close or downwind of intense sources of aerosols, could be more favorable for rainfall enhancement due to aerosols for the aerosol concentrations typical of this area.

  16. Pcr by Thermal Convection

    NASA Astrophysics Data System (ADS)

    Braun, Dieter

    The Polymerase Chain Reaction (PCR) allows for highly sensitive and specific amplification of DNA. It is the backbone of many genetic experiments and tests. Recently, three labs independently uncovered a novel and simple way to perform a PCR reaction. Instead of repetitive heating and cooling, a temperature gradient across the reaction vessel drives thermal convection. By convection, the reaction liquid circulates between hot and cold regions of the chamber. The convection triggers DNA amplification as the DNA melts into two single strands in the hot region and replicates into twice the amount in the cold region. The amplification progresses exponentially as the convection moves on. We review the characteristics of the different approaches and show the benefits and prospects of the method.

  17. Gliding in convection currents

    NASA Technical Reports Server (NTRS)

    Georgii, W

    1935-01-01

    A survey of the possibilities of gliding in convection currents reveals that heretofore only the most simple kind of ascending convection currents, that is, the "thermic" of insolation, has been utilized to any extent. With the increasing experience in gliding, the utilization of the peculiar nature of the "wind thermic" and increased glider speed promises further advances. Evening, ocean, and height "thermic" are still in the exploration stage, and therefore not amenable to survey in their effects.

  18. Effects of major storms on Pacific Islands

    USGS Publications Warehouse

    Richmond, Bruce

    1994-01-01

    Tropical storms of various kinds are as much a depositional event as an erosional event. Much attention is given to the destructive aspects of major storms because of the loss of life and property, but little is known about their beneficial effects to coastal accretion. While we can usually measure and map the instantaneous effects of a tropical storm, we can only speculate about the long-term effects. Geologic mapping by the U.S. Geological Survey in areas prone to storm effects can give us opportunities to minimize losses by identifying locations most likely to suffer.

  19. Scaling and Variability of Global Storms

    NASA Astrophysics Data System (ADS)

    Esmaili, R.; Tian, Y.; Vila, D. A.

    2014-12-01

    Storms are tracked continuously on the globe for a decade with high-resolution satellite observations, and their statistical and dynamical characteristics over a wide range of spatial and temporal scales are studied. With a Lagrangian tracking algorithm, the study yields detailed storm evolution and spatial distributions based on global, high-resolution (30-min, 4-km), satellite datasets. Statistical analysis and scaling studies are performed on the extensive storm database, and have produced new insight into the global storm system, such as (1) the spatial and temporal characteristics of global trajectories, (2) scaling properties, (3) the climatology and variability, and (4) life cycle evolution of storms. Our results documented the scaling of various storm properties, the seasonal storm climatology, variability, and the regional preferences for formation and dissipation. Additionally, we found that El Nino and La Nina impact storm tracks and properties. By continuously following storms, we examined their development over time. This is relevant to the measurement community because past studies have linked uncertainties in precipitation measurements to life cycle stage and overpass gaps. These results can be used to develop a baseline climatological state, improve retrieval algorithms, and examine extreme events.

  20. On the watch for geomagnetic storms

    USGS Publications Warehouse

    Green, Arthur W.; Brown, William M., III

    1997-01-01

    Geomagnetic storms, induced by solar activity, pose significant hazards to satellites, electrical power distribution systems, radio communications, navigation, and geophysical surveys. Strong storms can expose astronauts and crews of high-flying aircraft to dangerous levels of radiation. Economic losses from recent geomagnetic storms have run into hundreds of millions of dollars. With the U.S. Geological Survey (USGS) as the lead agency, an international network of geomagnetic observatories monitors the onset of solar-induced storms and gives warnings that help diminish losses to military and commercial operations and facilities.

  1. Storm resampling for uncertainty analysis of a multiple-storm unit hydrograph

    Microsoft Academic Search

    Bing Zhao; Yeou-Koung Tung; Keh-Chia Yeh; Jinn-Chuan Yang

    1997-01-01

    Due to various types of uncertainties involved in the estimation of a unit hydrograph (UH), the UH derived by any method is subject to uncertainties. Based on the concept of the bootstrap resampling technique, a practical methodology called storm resampling is proposed to quantify the uncertainties of multiple-storm UH ordinates and any parameters involved in the estimation of the multiple-storm

  2. Differences in convective intensity, stratiform precipitation fraction, and size of MCSs between continents, oceans, and monsoon regions

    NASA Astrophysics Data System (ADS)

    Zipser, E. J.; Liu, C.; xu, W.

    2012-12-01

    The long-term database from the TRMM (Tropical Rainfall Measuring Mission) satellite, now exceeding 14 years, has been useful not just for rainfall estimation, but for describing storm structures around the world between 36 N and 36 S. Although it has been known for some time that convective intensity is greater over continents than over oceans, data from the TRMM radar, passive microwave radiometer, and lightning imaging sensor have quantified the geographic, seasonal, and diurnal distribution of intense convection. This presentation shows many respects in which monsoon regions can be considered as intermediate between the extremes of continental and oceanic convection. In addition to proxies for convective intensity, we compare selected continental, oceanic, and monsoon regimes for convective vs. stratiform rainfall fraction, and for size of contiguous convective regions and for size of contiguous precipitation features. Within the east Asian and Australian monsoon regimes, the properties of deep convection and mesoscale convective systems during rainy periods tend to resemble oceanic convection, and during break periods tend to resemble continental convection. These differences are examined to learn whether they can be attributed to the nature of large-scale and mesoscale forcing in the various regions.

  3. Tropical Storm Iniki, Central Pacific

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Tropical Storm Iniki in the North Pacific (40.5N, 152.5W) was dissipating from hurricane status when this photo was taken. Two days prior, as a full fledged hurricane, with winds of about 150 mph and waves of over 15 ft., it swept over the Hawaiian island of Kauai. But, as Iniki moved over the colder waters of the North Pacific, it began to weaken as can be seen by the lack of a tight spiral gyre and the absence of an eye in the center.

  4. Biophysical effects of a decadal shift in summer wind direction over the Laurentian Great Lakes

    E-print Network

    NOAA Great Lakes Environmental Research Laboratory, Episodic Events

    migration of the dominant summer storm track. In Green Bay (NW Lake Michigan), we show that the new wind field has most likely resulted in a decrease in water mass exchange with Lake Michigan leading of a wind shift over Green Bay are particularly relevant to understanding pollution loading to Lake Michigan

  5. Evidence for the Convective Transport of Dust Aerosol During DC-3

    NASA Astrophysics Data System (ADS)

    Corr, C.; Ziemba, L. D.; Beyersdorf, A. J.; Moore, R.; Winstead, E.; Thornhill, K. L., II; Shook, M.; Anderson, B. E.; Lawson, P.; Froyd, K. D.; Ryerson, T. B.; Peischl, J.; Pollack, I. B.; Scheuer, E. M.; Dibb, J. E.

    2014-12-01

    Bulk aerosol composition and aerosol volume size distributions measured aboard the NASA DC-8 during the NCAR DC-3 (Deep Convective Clouds and Chemistry Experiment) mission in May/June 2012 were used to investigate the transport of mineral dust through twelve storms encountered over Colorado and Oklahoma. Measurements made at low altitudes (< 5 km) in the storm inflow region were compared to those made in the outflow in and around storm cirrus anvils (altitude > 9 km). Total coarse (1 ?m < diameter < 5 ?m) aerosol volume (Vc) and Ca2+ measured in both storm inflow and outflow were highly correlated, thus dust was assumed to dominate the aerosol coarse volume. Mean outflow Ca2+ concentrations were comparable to mean inflow values as demonstrated by average outflow/inflow Ca2+ ratios near unity. Vc outflow/inflow ratios were also high (>> 0.5) for most storms, suggesting coarse mode dust was efficiently transported through the CO and OK storms. Comparisons between inflow aerosol number concentration (Nc) calculated over a size range characteristic of dust ice nuclei (0.5 ?m < diameter < 5 ?m) and ice particle concentrations in storm anvils further suggested interstitial coarse mode dust was present in these cirrus anvils. For over half the storms, mean inflow Nc exceeded mean anvil ice particle concentrations implying ice nucleation mechanisms may be sensitive to complex dust characteristics beyond size. Possible artifacts associated with shattered ice crystals were examined via 1) closure calculations for observations from different instrumentation and independent aircraft inlets, and 2) assessment of relationships with cloud microphysical observations. Initial results indicate minimal influence of ice shatter on aerosol measurements, but effects vary for individual storms with different cloud microphysical characteristics.

  6. Structure of the Highly Sheared Tropical Storm Chantal During CAMEX-4

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Tropical Storm Chantal during August 2001 was a storm that failed to intensify over the few days prior to making landfall on the Yucatan Peninsula. An observational study of Tropical Storm Chantal is presented using a diverse data set including remote and in situ measurements from the NASA ER-2 and DC-8 and the NOAA WP-3D N42RF aircraft and satellite data. The authors discuss the storm structure from the larger scale environment down to the convective scale. Large vertical shear (850-200 hPa shear magnitude range 8-15 m/s) plays a very important role in preventing Chantal from intensifying. The storm had a poorly defined vortex that only extended up to 5-6 km altitude, and an adjacent intense convective region that comprised an MCS. The entire low-level circulation center was in the rain-free western side of the storm, about 80 km to the west-southwest of the MCS. The MCS appears to have been primarily the result of intense convergence between large-scale, low-level easterly flow with embedded downdrafts, and the cyclonic vortex flow. The individual cells in the MCS such as Cell 2 during the period of the observations, were extremely intense with reflectivity core diameters of 10 km and peak updrafts exceeding 20 m/s. Associated with this MCS were two broad subsidence (warm) regions both of which had portions over the vortex. The first layer near 700 hPa was directly above the vortex and covered most of it. The second layer near 500 hPa was along the forward and right flanks of Cell 2 and undercut the anvil divergence region above. There was not much resemblance of these subsidence layers to typical upper level warm cores in hurricanes that are necessary to support strong surface winds and a low central pressure. The observations are compared to previous studies of weakly sheared storms and modeling studies of shear effects and intensification. Additional information is included in the original extended abstract.

  7. A seismic signature of river bedload transport during storm events

    E-print Network

    Hsu, Leslie; Finnegan, Noah J.; Brodsky, Emily E.

    2011-01-01

    and the one large storm in 2009, Typhoon Morakot. Figure 1.beginning of the storm in all three typhoon events. This keytyphoons examined, net channel bed aggradation would be required during each storm

  8. ORIGINAL PAPER Design and quantification of an extreme winter storm

    E-print Network

    , barometric pressures (for consideration of storm surges and coastal erosion), and winds over California were floods, storm surges and surf, and coastal erosion. Nonetheless, winter storms have often been consid

  9. M. Bahrami ENSC 388 (F09) Natural Convection 1 Natural Convection

    E-print Network

    Bahrami, Majid

    Convection 1 Natural Convection In natural convection, the fluid motion occurs by natural means such as buoyancy. Since the fluid velocity associated with natural convection is relatively low, the heat transfer coefficient encountered in natural convection is also low. Mechanisms

  10. Impacts of a Fire Smoke Plume on Deep Convective Clouds Observed during DC3

    NASA Astrophysics Data System (ADS)

    Takeishi, A.; Storelvmo, T.; Zagar, M.

    2014-12-01

    While the ability of aerosols to act as cloud condensation nuclei (CCN) and ice nuclei (IN) is well recognized, the effects of changing aerosol number concentrations on convective clouds have only been studied extensively in recent years. As deep convective clouds can produce heavy precipitation and may sometimes bring severe damages, especially in the tropics, we need to understand the changes in the convective systems that could stem from aerosol perturbations. By perturbing convective clouds, it has also been proposed that aerosols can affect large-scale climate. According to the convective invigoration mechanism, an increase in the aerosol concentration could lead to a larger amount of rainfall and higher vertical velocities in convective clouds, due to an increase in the latent heat release aloft. With some of the satellite observations supporting this mechanism, it is necessary to understand how sensitive the model simulations actually are to aerosol perturbations. This study uses the Weather Research and Forecasting (WRF) model as a cloud-resolving model to reproduce deep convective clouds observed during the Deep Convective Clouds and Chemistry (DC3) field campaign. The convective cloud of our interest was observed in northeastern Colorado on June 22nd in 2012, with a plume of forest fire smoke flowing into its core. Compared to other convective cells observed in the same area on different days, our aircraft data analysis shows that the convective cloud in question included more organic aerosols and more CCN. These indicate the influence of the biomass burning. We compare the results from simulations with different microphysics schemes and different cloud or ice number concentrations. These sensitivity tests tell us how different the amount and the pattern of precipitation would have been if the aerosol concentration had been higher or lower on that day. Both the sensitivity to aerosol perturbation and the reproducibility of the storm are shown to highly depend on the choice of the microphysics scheme.

  11. Alabama Ground Operations during the Deep Convective Clouds and Chemistry Experiment

    NASA Technical Reports Server (NTRS)

    Carey, Lawrence; Blakeslee, Richard; Koshak, William; Bain, Lamont; Rogers, Ryan; Kozlowski, Danielle; Sherrer, Adam; Saari, Matt; Bigelbach, Brandon; Scott, Mariana; Schultz, Elise; Schultz, Chris; Gatlin, Patrick; Wingo, Matt; Phillips, Dustin; Phillips, Chris; Peterson, Harold; Bailey, Jeff; Frederickson, Terryn; Hall, John; Bart, Nicole; Becker, Melissa; Pinkney, Kurtis; Rowe, Scott; Starzec, Mariusz

    2013-01-01

    The Deep Convective Clouds and Chemistry (DC3) field campaign investigates the impact of deep, midlatitude convective clouds, including their dynamical, physical and lighting processes, on upper tropospheric composition and chemistry. DC3 science operations took place from 14 May to 30 June 2012. The DC3 field campaign utilized instrumented aircraft and ground ]based observations. The NCAR Gulfstream ]V (GV) observed a variety of gas ]phase species, radiation and cloud particle characteristics in the high ]altitude outflow of storms while the NASA DC ]8 characterized the convective inflow. Groundbased radar networks were used to document the kinematic and microphysical characteristics of storms. In order to study the impact of lightning on convective outflow composition, VHF ]based lightning mapping arrays (LMAs) provided detailed three ]dimensional measurements of flashes. Mobile soundings were utilized to characterize the meteorological environment of the convection. Radar, sounding and lightning observations were also used in real ]time to provide forecasting and mission guidance to the aircraft operations. Combined aircraft and ground ]based observations were conducted at three locations, 1) northeastern Colorado, 2) Oklahoma/Texas and 3) northern Alabama, to study different modes of deep convection in a variety of meteorological and chemical environments. The objective of this paper is to summarize the Alabama ground operations and provide a preliminary assessment of the ground ]based observations collected over northern Alabama during DC3. The multi ] Doppler, dual ]polarization radar network consisted of the UAHuntsville Advanced Radar for Meteorological and Operational Research (ARMOR), the UAHuntsville Mobile Alabama X ]band (MAX) radar and the Hytop (KHTX) Weather Surveillance Radar 88 Doppler (WSR ]88D). Lightning frequency and structure were observed in near real ]time by the NASA MSFC Northern Alabama LMA (NALMA). Pre ]storm and inflow proximity soundings were obtained with the UAHuntsville mobile sounding unit and the Redstone Arsenal (QAG) morning sounding.

  12. Low-energy ion precipitation during the Halloween storm

    NASA Astrophysics Data System (ADS)

    Huang, C. Y.; Burke, W. J.; Lin, C. S.

    2007-02-01

    During the Halloween storm of October 29 31, 2003, four defense meteorological satellite program (DMSP) satellites detected fluxes of low-energy ions precipitating well equatorward of auroral electrons in the dawn/morning magnetic local time sector during the main phase. There were three southward turnings of the interplanetary magnetic field (IMF), leading to three intensifications of the ring current to DST values of -125, -310 and -350 nT. In each case the ion fluxes weakened dramatically and/or vanished during DST recoveries. DMSP only encountered short-lived episodes of subauroral ion precipitation in the dusk/evening sector. A brief survey of the DMSP database reveals that near-dawn, ion precipitation is a main-phase characteristic of all large magnetic storms. DMSP satellites also detected similar ion precipitation during the main phase of the March 1991 magnetic storm. During an outbound pass of the combined release radiation effect satellite (CRRES) through the inner magnetosphere it detected low energy (<1 keV) ion fluxes that were collocated with, but spectrally separated in energy from the ring current “nose structure”. As CRRES moved toward perigee in the dawn sector, it crossed similar low-energy (?500 eV) ions embedded in a broad ion population, located earthward of plasma sheet electrons. Simultaneously the DMSP F8 satellite detected spectrally similar low-energy ions precipitating at subauroral latitudes near dawn at the same invariant latitudes. To reconcile DMSP/CRRES observations with elementary concepts of allowed ion drift paths, the data suggest two source populations. The lowest-energy ions, of ionospheric origin, were initially energized earthward of the plasma sheet electron boundary in the evening local-time sector then co-rotated eastward. Higher-energy ions originated in the plasma sheet and drifted close to the Earth under the combined influences of time-varying convective electric fields and azimuthal gradients in the Earth's magnetic field generated by the stormtime ring current [Tsyganenko, N.A., Singer, H. J., Kasper, J. C., 2003. Storm-time distortion of the inner magnetosphere: how severe can it get? Journal of Geophysical Research, 108 (A5), 1209].

  13. Boundary Layer Structure and Processes in Mid - Ocean Storms.

    NASA Astrophysics Data System (ADS)

    Bond, Nicholas A.

    Measurements taken during the Storm Transfer and Response Experiment (STREX) are used to analyze boundary layer structures and processes in the vicinity of North Pacific storms. Case studies are carried out for the pre -frontal, post-frontal, and frontal sectors of storms. The effects of sub-grid scale processes on the boundary layer and the overlying atmosphere receive special emphasis. The pre-frontal boundary layers are nearly neutrally stratified and the surface heat and moisture fluxes are small. The surface fluxes tend to be downward just ahead of the fronts and are of greater magnitude during stronger storms. Even though the actual entrainment velocities are small, the entrainment fluxes are generally the most important sources of total heat for the pre-frontal boundary layers. Entrainment rates determined from budgets compare well with results calculated from relationships determined in laboratory studies of shear-driven entrainment. Heat and moisture budgets are evaluated in two post-frontal situations. In both cases surface heat and moisture fluxes are the dominant sources of total heating within the boundary layers. The entrainment velocities are larger in post-frontal than pre-frontal regions, but entrainment has only a small and positive net effect on the total heat content of the post-frontal boundary layers. Penetrative convection represents the major sink of boundary layer moisture for the case with a long atmospheric fetch over the ocean. A single strong cold front is analysed. The Sawyer Eliassen secondary circulation equation is used to compare the effects of geostrophic forcing, diabatic heating, and friction on the synoptic-scale ageostrophic flow at the front. Friction is found to be the primary process forcing the low-level updraft at the front. Combined kinematic and thermodynamic analyses show strong relative inflow of warm boundary layer air toward the front from the east and a weaker inflow of cold air from the west. The frontogenetical processes are evaluated and compared with those from previous studies. It is proposed that the intensity of turbulent mixing limits the scale of a front.

  14. Long-lived convective chimneys in the Greenland sea and their climatic role

    Microsoft Academic Search

    P. Wadhams; J. P. Wilkinson; V. Pavlov; E. Hansen; G. Budeus

    2003-01-01

    The longest-lived convective chimney yet detected in the world ocean was first mapped in the central Greenland Sea (75degN, 0degE) in March 2001 and has been observed during the succeeding summer, winter and summer for a total of 18 months. It is 10 km in diameter and extends to a depth of 2500 m. It has remained relatively stationary during

  15. Summer English Language Program Summer 2014

    E-print Network

    Hitchcock, Adam P.

    1811-1887 I benefited from every class of McMaster University's Summer ESL Program: the morning lecture walking distance of campus where students can purchase a wide variety of groceries. Facilities Students facilities. Campus security is onsite 24 hours a day. 4 | McMaSTeR eNGlISH laNGUaGe PROGRaM SUMMeR 2014 That

  16. Review of urban storm water models

    Microsoft Academic Search

    Christopher Zoppou

    2001-01-01

    This paper reviews models for simulating storm water quantity and quality in an urban environment. This has been achieved by examining a number of storm water models in current use. The important features of twelve models, which represent a wide range of capabilities and spatial and temporal resolution have been described. Specific topics covered are: identifying important urban water quality

  17. AUTOMATED STORM WATER SAMPLING ON SMALL WATERSHEDS

    Microsoft Academic Search

    R. D. Harmel; K. W. King; R. M. Slade

    Few guidelines are currently available to assist in designing appropriate automated storm water sampling strategies for small watersheds. Therefore, guidance is needed to develop strategies that achieve an appropriate balance between accurate characterization of storm water quality and loads and limitations of budget, equipment, and personnel. In this article, we explore the important sampling strategy components (minimum flow threshold, sampling

  18. Modeling coliforms in storm water plumes

    Microsoft Academic Search

    J. Alex McCorquodale; Ioannis Georgiou; Susanne Carnelos; Andrew J. Englande

    2004-01-01

    The recreational waters near many large cities in the United States and Canada are severely impaired by pathogens that are present in the storm water runoff. In separated sewers the pathogen sources may be cross-flows between the sanitary and storm water systems. This paper presents the methodology that was used in developing a forecasting model for pathogen indicators for recreational

  19. Solar noise storms and magnetic sector structures

    Microsoft Academic Search

    R. T. Stewart

    1985-01-01

    A synoptic study of the occurrence and polarization of 160 MHz noise storms recorded at Culgoora during the current solar cycle shows that the storm sources occur in large unipolar cells extending more than 90 deg in solar longitude and less than about 60 deg in latitude, with lifetimes of about 1 yr. From solar maximum onwards these large cells

  20. Solar noise storms and magnetic sector structures

    Microsoft Academic Search

    R. T. Stewart

    1985-01-01

    A synoptic study of the occurrence and polarization of 160 MHz noise storms recorded at Culgoora during the current solar cycle shows that the storm sources occur in large unipolar cells extending >90° in solar longitude and ?60° in latitude, with lifetimes of ~ 1 yr. From solar maximum onwards these large cells stretch across the solar equator to form

  1. MEASURED WINTER PERFORMANCE OF STORM WINDOWS

    E-print Network

    MEASURED WINTER PERFORMANCE OF STORM WINDOWS J. H. Klems Windows and Daylighting Group, Building comparison measurements were made between various prime/storm window combinations and a well-weatherstripped, single-hung replacement window with a low-E selective glazing. Measurements were made using an accurate

  2. The storm-time equatorial electrojet

    Microsoft Academic Search

    K. Burrows; T. S. G. Sastry; S. Sampath; J. D. Stolarik; M. J. Usher

    1976-01-01

    A Petrel rocket carrying a double cell rubidium magnetometer was launched from the Thumba Equatorial Rocket Launching Station during the early main phase of a magnetic storm. No ionospheric currents associated with the storm were observed and the large field depression, at the flight time, must therefore be attributed to currents at higher altitudes. The equatorial enhancement of ionospheric magnetic

  3. The storm-time equatorial electrojet

    Microsoft Academic Search

    K. Burrows; T. S. G. Sastry; S. Sampath; J. D. Stolarik; M. J. Usher

    1977-01-01

    A Petrel rocket carrying a double cell rubidium magnetometer was launched from the Thumba Equatorial Rocket Launching Station during the early main phase of a magnetic storm. No ionospheric currents associated with the storm were observed, and the large field depression at the flight time must therefore be attributed to currents at higher altitudes. The equatorial enhancement of ionospheric magnetic

  4. Storm Surge Sensor During Hurricane Irene

    USGS Multimedia Gallery

    During hurricanes the USGS deploys storm-surge monitoring instruments along the coasts, sounds, and bays in impacted areas to gauge how high hurricanes push water in rivers, bays and other areas. The sensors are crucial for forecasting future storms and assessing hurricane damage. They are strapped ...

  5. The Generation of a Mesoscale Convective System from Mountain Convection

    E-print Network

    Tucker, Donna F.; Crook, N. Andrew

    1999-06-01

    A mesoscale convective system (MCS) that formed just to the east of Denver is investigated with a nonhydrostatic numerical model to determine which processes were important in its initiation. The MCS developed from outflow from previous convective...

  6. A case study of Ionospheric storm effects during long-lasting southward IMF Bz driven geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Liu, J., Sr.

    2014-12-01

    Multiple instrumental observations including GPS TEC, foF2 and hmF2 from ionosondes, vertical ion drift measurements from C/NOFS, magnetometer data and far-ultraviolet airglow measured by TIMED/GUVI are used to investigate the profound ionospheric disturbances at mid- and low-latitudes during the 14-17 July 2012 geomagnetic storm event, which was featured by prolonged southward interplanetary geomagnetic field component for about 30 hours below -10 nT. In the East Asian/Australian sector, latitudinal profile of TEC variations in the main phase were characterized by three bands of increments and separated by weak depressions in the Equatorial Ionospheric Anomaly (EIA) crest regions, which were caused by the combined effects of disturbance dynamo electric fields (DDEF) and equatorward neutral winds. In the recovery phase, strong inhibition of EIA occurred and the summer crest of EIA disappeared on 16 July due to the combined effects of intrusion of neutral composition disturbance zone as shown by the TIME/GUVI O/N2 measurements and long-lasting daytime westward DDEF inferred from the equatorial electric electrojet (EEJ) observations. The transit time of DDEF over the dip equator from westward to eastward is around 2200 LT. In the American longitude, the salient ionospheric disturbances in the summer hemisphere were characterized by daytime periodical intrusion of negative phase for three consecutive days in the recovery phase, preceded by storm enhanced density (SED) plume in the initial phase. In addition, multiple short-lived prompt penetration electric ?elds (PPEF) appeared during stable southward IMF Bz in the recovery phase and were responsible for enhanced the EIA and equatorial ionospheric uplift around sunset.

  7. Anomalously weak solar convection.

    PubMed

    Hanasoge, Shravan M; Duvall, Thomas L; Sreenivasan, Katepalli R

    2012-07-24

    Convection in the solar interior is thought to comprise structures on a spectrum of scales. This conclusion emerges from phenomenological studies and numerical simulations, though neither covers the proper range of dynamical parameters of solar convection. Here, we analyze observations of the wavefield in the solar photosphere using techniques of time-distance helioseismology to image flows in the solar interior. We downsample and synthesize 900 billion wavefield observations to produce 3 billion cross-correlations, which we average and fit, measuring 5 million wave travel times. Using these travel times, we deduce the underlying flow systems and study their statistics to bound convective velocity magnitudes in the solar interior, as a function of depth and spherical-harmonic degree ?. Within the wavenumber band ? < 60, convective velocities are 20-100 times weaker than current theoretical estimates. This constraint suggests the prevalence of a different paradigm of turbulence from that predicted by existing models, prompting the question: what mechanism transports the heat flux of a solar luminosity outwards? Advection is dominated by Coriolis forces for wavenumbers ? < 60, with Rossby numbers smaller than approximately 10(-2) at r/R([symbol: see text]) = 0.96, suggesting that the Sun may be a much faster rotator than previously thought, and that large-scale convection may be quasi-geostrophic. The fact that isorotation contours in the Sun are not coaligned with the axis of rotation suggests the presence of a latitudinal entropy gradient. PMID:22665774

  8. Convective quasi-equilibrium

    NASA Astrophysics Data System (ADS)

    Yano, J.-I.; Plant, R. S.

    2012-12-01

    The concept of convective quasi-equilibrium (CQE) is a key ingredient in order to understand the role of deep moist convection in the atmosphere. It has been used as a guiding principle to develop almost all convective parameterizations and provides a basic theoretical framework for large-scale tropical dynamics. The CQE concept as originally proposed by Arakawa and Schubert (1974) is systematically reviewed from wider perspectives. Various interpretations and extensions of Arakawa and Schubert's CQE are considered both in terms of a thermodynamic analogy and as a dynamical balance. The thermodynamic interpretations can be more emphatically embraced as a homeostasis. The dynamic balance interpretations can be best understood by analogy with the slow manifold. Various criticisms of CQE can be avoided by taking the dynamic balance interpretation. Possible limits of CQE are also discussed, including the importance of triggering in many convective situations, as well as the possible self-organized criticality of tropical convection. However, the most intriguing aspect of the CQE concept is that in spite of many observational tests supporting and interpreting it in many different senses, it has never been established in a robust manner based on a systematic analysis of the cloud work function budget by observations as was originally defined.

  9. The evolution of misoscale circulations in a downburst-producing storm and comparison to numerical results

    NASA Technical Reports Server (NTRS)

    Kessinger, C. J.; Wilson, J. W.; Weisman, M.; Klemp, J.

    1984-01-01

    Data from three NCAR radars are used in both single and dual Doppler analyses to trace the evolution of a June 30, 1982 Colorado convective storm containing downburst-type winds and strong vortices 1-2 km in diameter. The analyses show that a series of small circulations formed along a persistent cyclonic shear boundary; at times as many as three misocyclones were present with vertical vorticity values as large as 0.1/s using a 0.25 km grid interval. The strength of the circulations suggests the possibility of accompanying tornadoes or funnels, although none were observed. Dual-Doppler analyses show that strong, small-scale downdrafts develop in close proximity to the misocyclones. A midlevel mesocyclone formed in the same general region of the storm where the misocylones later developed. The observations are compared with numerical simulations from a three-dimensional cloud model initialized with sounding data from the same day.

  10. Observations and Simulations of the M-I Coupling of Bursty Convection

    NASA Technical Reports Server (NTRS)

    Sanchez, Ennio R.

    2001-01-01

    The ultimate aim of the project is to establish how much of the magnetotail's total potential is due to flow bursts and how much of this potential maps to the ionosphere. In order to quantify these contributions, we further developed a method to measure the total cross-polar cap potential and the total reconnection rate across the entire polar cap boundary. Then we applied the method to different solar wind-magnetosphere-ionosphere conditions that included substorm periods, storms, and steady magnetospheric convection (SMCs, also known as convection bays) periods. In the following section, we describe in more detail the activities during the second year of this grant.

  11. [Relationship Between Core Convective Structure and Intensity Change in Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The downshear reformation of Tropical Storm Gabrielle (2001) was investigated using radar reflectivity and lightning data that were nearly continuous in time, as well as frequent aircraft reconnaissance fights. Initially the storm was a marginal tropical storm in an environment with strong 850-200 hPa vertical wind shear of 12-13 m/s and an approaching upper tropospheric trough. Both the observed outflow and an adiabatic balance model calculation showed that the radial-vertical circulation increased with time as the trough approached. Convection was highly asymmetric, with almost all radar return located in one quadrant left of downshear in the storm. Reconnaissance data show that an intense mesovortex formed downshear of the original center. This vortex was located just south of: rather than within, a strong downshear left lightning outbreak, consistent with tilting of the horizontal vorticity associated with the vertical wind shear. The downshear mesovortex contained a 972 hPa minimum central pressure, 20 hPa lower than minimum pressure in the original vortex just three hours earlier. The mesovortex became the new center of the storm, but weakened somewhat prior to landfall. It is argued that dry air carried around the storm from the region of upshear subsidence, as well as the direct effects of the shear, prevented the reformed vortex from continuing to intense.

  12. Effects of storm paths on precipitation chemistry, and variations of within-storm chemistry during selected storms in central Massachusetts, 1986-87

    USGS Publications Warehouse

    Risley, J.C.; Shanley, J.B.

    1994-01-01

    Samples of precipitation from 31 storms were collected from October 1986 through December 1987 at a site near Quabbin Reservoir in central Massachusetts and were analyzed for pH, specific conductance, and concentrations of common chemical constituent. Twenty-four storms followed a conti- nental path west of the Appalachian Mountains. The remaining seven storms followed a coastal path east of the Appalachian Mountains along the Atlantic Coast. Precipitation from the continental storms was more acidic than precipitation from the coastal storms according to a nonparametric statistical com- parison. Because the continental storms had less volume, the loads of hydrogen ions and other common chemical constituents from both groups were not statistically different. The variability of within- storm precipitation chemistry was evaluated for 8 of the 31 storms. Seven of the storms showed evidence of suspended-particulate removal at levels between the cloud layer and the land surface during their early stages. The remaining storm, also the most acidic, showed evidence of suspended- particulate removal within the cloud layer as indicated by a relatively constant pH throughout the storm. Surface-air concentrations of sulfur dioxide and nitrogen dioxide before, during, and after each of the eight storms were compared to within-storm values of pH and precipitation. Seven of the storms were accompanied by decreased atmospheric concen- trations of both sulfur dioxide and nitrogen dioxide in the early stages of the storm. For three of the storms, atmospheric concentrations of sulfur dioxide and nitrogen dioxide were higher during the 24-hour period after the storm than the 24-hour period pre- ceding the storm. Particulates in precipitation samples were analyzed for three storms. Biotite was the predominant mineral in two of the storms. Other minerals detected were garnet, quartz, gypsum, hematite, epidote, ilmenite, eggonite, halite, rutile, and organic ash.

  13. Global Distribution of Different Forms of Convection as Seen by TRMM

    NASA Astrophysics Data System (ADS)

    Houze, Robert; Rasmussen, Kristen; Zuluaga, Manuel; Brodzik, Stella

    2015-04-01

    For 17 years the Tropical Rainfall Measuring Mission (TRMM) satellite collected data with its Ku-band Precipitation Radar (PR) over the low latitudes, where convective clouds dominate rainfall. The three-dimensional character of the radar data allows echo objects to be defined that indicate the different forms taken by convection. Analysis of these echo objects over the entire tropics indicate that the nature of convection and its lifecycles vary regionally, with respect to ocean, land, mountains, and the large-scale meteorological environment. This study is based on three types of echo objects representing extreme forms of convection: Deep convective cores (DCCs), which are three-dimensional towers of radar echo exceeding a high intensity threshold and extending high into the upper troposphere; wide convective cores (WCCs), which are three-dimensional elements defined by a high reflectivity threshold and covering horizontal area of mesoscale proportions; and broad stratiform regions (BSRs), for which a contiguous region of stratiform echo covers an especially large area. These echo objects are not isolated but rather are embedded within larger storms or mesoscale convective systems (MCSs). Embedded DCCs characterize storms in an early stage of development. The presence of WCCs indicates MCSs that are maturing, growing upscale to become MCSs. Embedded BSRs are found in robust mature MCSs in late stages of development. Some patterns that emerge from the global distribution of DCCs, WCCs, and BSRs in the 17-year TRMM dataset are that the behavior of these forms of convection varies between land and ocean. DCCs and WCCs are not as deep, wide, or intense over tropical oceans as observed over land, with the exception of Amazonia, where these forms of convection are similar to those over oceanic regions. Over tropical continents (Africa and South America) and the South Asian subcontinent, these echo objects are generally deeper and more intense. Over land regions, storms containing DCCs initiate near major mountain ranges (viz. the Himalayas and Andes). Global patterns of the forms of convection containing DCCs, WCCs, and BSRs are strongly affected by large-scale environmental and topographic conditions. Near the Andes and Himalayas, midlevel flow over mountains caps moist low-level flows until strong convection can be triggered to break through the cap. As a result, storms containing the most extreme DCCs occur close to these mountain ranges. Large-scale flow patterns are key to whether storms can grow upscale to form the most intense MCSs. This fact is illustrated most strongly over the oceans by the Madden-Julian Oscillation (MJO), wherein storms achieve maximum maturity with the largest BSRs in active phases of the MJO. Over land the influence of large-scale motion patterns is indicated by the fact that systems with embedded WCCs and BSRs are favored by African easterly wave troughs over equatorial Africa, while over subtropical South America, baroclinic waves extending into lower latitudes favor such development of MCSs initiating near the Andes.

  14. Specific differential phase observations of multicell convection during natural and triggered lightning strikes at the International Center for Lightning Research and Testing

    NASA Astrophysics Data System (ADS)

    Hyland, P.; Biggerstaff, M. I.; Uman, M. A.; Hill, J. D.; Krehbiel, P. R.; Rison, W.

    2012-12-01

    During the summers of 2011-2012, a C-band polarimetric Shared Mobile Atmospheric Research and Teaching (SMART) radar from the University of Oklahoma was deployed to Keystone Heights, FL to study the relationship between cloud structure and the propagation of triggered and natural lightning channels. The radar was operated in Range-Height-Indicator (RHI) volume scanning mode over a narrow azimuthal sector that provided high spatial vertical resolution every 90 seconds over the rocket launch facility at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, FL. In this presentation, we will focus on observations collected in 2011. Seven successful triggers (with return strokes) out of 20 attempts were sampled by the SMART-R from June to August. Most of the trigger attempts occurred during the dissipating stages of convection with steady ground electric field values. Specific differential phase (KDP) showed evidence of ice crystal alignment due to strong electric fields within the upper portions of the convection over ICLRT around the time of launch attempts. Consecutive RHI sweeps over ICLRT revealed changes in KDP that suggested the building of electric fields and subsequent relaxation after a triggered flash. KDP signatures relative to other radar variables will also be investigated to determine the microphysical and convective nature of the storms in which natural and triggered lightning strikes occurred. Lightning Mapping Array (LMA) sources of the triggered flash channels showed a preference for horizontal propagation just above the radar bright band associated with the melting layer. This finding agrees with several past studies that used balloon soundings and found intense layers of charge near the 0°C isotherm. The propagation path also seemed to be related to the vertical distribution of KDP in some of the triggered flashes. A preferred path through areas of generally positive values of KDP suggests that triggered lightning channels may favor those regions of the cloud with net charge, possibly due to melting charging mechanisms, or areas where more active convection may be lofting supercooled liquid water and graupel particles, providing additional regions of charge that can be tapped by the propagating lightning channel. A comparison of natural and triggered lightning strikes with respect to the distribution of KDP will provide an indication of whether the propagation paths are similar.

  15. Combined buoyancy-thermocapillary convection

    NASA Technical Reports Server (NTRS)

    Homsy, G. M.

    1990-01-01

    Combined buoyancy-thermocapillary convection was studied in 2D and 3D. Fluid motion caused by thermally induced tension gradients on the free surface of a fluid is termed thermocapillary convection. It is well-known that in containerless processing of materials in space, thermocapillary convection is a dominant mechanism of fluid flow. Welding and crystal growth processes are terrestrial applications where thermocapillary convection has direct relevance.

  16. The relative contributions of summer and cool-season precipitation to groundwater recharge, Spring Mountains, Nevada, USA

    NASA Astrophysics Data System (ADS)

    Winograd, Isaac J.; Riggs, Alan C.; Coplen, Tyler B.

    A comparison of the stable-isotope signatures of spring waters, snow, snowmelt, summer (July thru September) rain, and cool season (October thru June) rain indicates that the high-intensity, short-duration summer convective storms, which contribute approximately a third of the annual precipitation to the Spring Mountains, provide only a small fraction (perhaps 10%) of the recharge to this major upland in southern Nevada, USA. Late spring snowmelt is the principal means of recharging the fractured Paleozoic-age carbonate rocks comprising the central and highest portion of the Spring Mountains. Daily discharge measurements at Peak Spring Canyon Creek during the period 1978-94 show that snowpacks were greatly enhanced during El Niño events. Résumé La comparaison des signatures isotopiques stables des eaux de sources, de neige, de fonte de neige, des pluies d'été (juillet à septembre) et de saison froide (octobre à juin) montre que les précipitations convectives d'été de forte intensité et de courte durée, apportant un tiers des précipitations annuelles reçues par les Monts Spring, ne participent que pour une faible part (10%) à la recharge de cette importante zone d'altitude du sud du Nevada (États-Unis). La fonte tardive de la neige au printemps constitue l'essentiel de la recharge des roches carbonatées fracturées d'âge paléozoïque formant la partie centrale et la plus haute des Monts Spring. Les données journalières de débit sur la rivière du canyon de Peak Spring, entre 1978 et 1994, montrent que les hauteurs de neige ont été plus élevées pendant les événements El Niño. Resumen La comparación entre las marcas isotópicas de aguas de manantiales, nieve, deshielo, lluvias de verano (julio a septiembre) y resto de lluvias (octubre a junio) indican que las tormentas de verano, de corta duración y gran intensidad, las cuales suponen alrededor de un tercio de la precipitación total anual en las Spring Mountains, proporcionan sólo una fracción pequeña (alrededor del 10%) de la recarga en esta zona al sur de Nevada (EE.UU.). El deshielo de finales de la primavera es la principal fuente de recarga de las rocas carbonatadas fracturadas de edad Paleozoica que forman las partes central y superior de las Spring Mountains. Las medidas de descarga diarias en el Desfiladero de Peak Spring Canyon durante 1978-94 muestran que los espesores de nieve aumentaron coincidiendo con los fenómenos de El Niño.

  17. Celebrate Summer with Reading

    NSDL National Science Digital Library

    Juliana Texley

    2007-07-01

    School is out and the summer is full of both official and unofficial holidays that prompt us to enjoy science and the profession of sharing it. As in past years, the reviewers and editors of NSTA Recommends --ready and willing to share their enthusiasm for reading with you--have been gathering suggestions for the summer. So along with your beach chairs, flags, and fireworks schedules; collect some reading material for a summer of personal enrichment.

  18. Copper disinfection ban causes storm.

    PubMed

    Lester, Alan

    2013-05-01

    Since 1 February this year, under the EU's Biocidal Products Directive, it has been illegal to sell or use water treatment systems that use elemental copper, a practice employed historically by a significant number of UK healthcare facilities to combat Legionella. Alan Lester, managing director of specialist supplier of 'environmentally-friendly' water treatment systems, Advanced Hydro, says the ban has caused 'a storm of giant proportion,' with advocates of copper ion-based treatment systems arguing that this disinfection method dates back 3,000 years to Egyptian times, making it an 'undoubtedly proven' technology. Here he explains why the ban came into force, considers why the UK's Health and Safety Executive (HSE) is seeking a derogation, looks at the ban's likely impact, and gives a personal viewpoint on the 'pros and cons' of some of the alternative treatment technologies, including a titanium dioxide-based system marketed by Advanced Hydro itself in the UK. PMID:23763088

  19. UCAR group urges STORM program

    NASA Astrophysics Data System (ADS)

    Richman, Barbara T.

    A blue-ribbon panel of scientists has proposed a decade-long, $1 billion program to improve forecasting operations and research of regional and local hazardous weather. The panel, appointed by the University Corporation for Atmospheric Research (UCAR), believes that the program could reduce the $20-billion annual cost of damage from severe weather by $1 billion per year.The primary aim of the program is to ‘enable weather services, public and private, to observe and predict stormscale weather phenomena— such as squall lines, thunderstorms, flash floods, local heavy snows, or tornadoes—with the accuracy and reliability to protect the public, serve the national economy, and meet defense requirements,’ as explained in the report, The National STORM (Stormscale Operational and Research Meteorology) Program: A Call to Action. Stormscale phenomena also include nonviolent weather: freezing rain, dense ground fog, low-lying clouds that disrupt ground or air traffic, persistent temperature inversions, and strong nocturnal cooling that may produce killing frost.

  20. 4, 36693698, 2004 Convective clouds

    E-print Network

    Paris-Sud XI, Université de

    ACPD 4, 3669­3698, 2004 Convective clouds and self-organisation F. J. Nober and H. F. Graf Title and Physics Discussions A new convective cloud field model based on principles of self-organisation F. J.ac.uk) 3669 #12;ACPD 4, 3669­3698, 2004 Convective clouds and self-organisation F. J. Nober and H. F. Graf

  1. Wave generation by turbulent convection

    NASA Technical Reports Server (NTRS)

    Goldreich, Peter; Kumar, Pawan

    1990-01-01

    Wave generation by turbulent convection in a plane parallel, stratified atmosphere lying in a gravitational field is studied. The turbulent spectrum is related to the convective energy flux via the Kolmogorov scaling and the mixing length hypothesis. Efficiencies for the conversion of the convective energy flux into both trapped and propagating waves are estimated.

  2. 5, 37473771, 2005 Convection impacts

    E-print Network

    Paris-Sud XI, Université de

    ACPD 5, 3747­3771, 2005 Convection impacts on tropospheric ozone and its precursors R. M. Doherty and Physics Discussions Influence of convective transport on tropospheric ozone and its precursors is licensed under a Creative Commons License. 3747 #12;ACPD 5, 3747­3771, 2005 Convection impacts

  3. Experiments on Thermally Driven Convection

    E-print Network

    Ahlers, Guenter

    Experiments on Thermally Driven Convection Guenter Ahlers ABSTRACT Experimental results for thermally driven convection in a thin horizontal layer of a nematic liquid crystal heated from below- culations. For the case of planar alignment in a horizontal field, convection occurs only when heating

  4. 5, 1102911054, 2005 Convective gravity

    E-print Network

    Paris-Sud XI, Université de

    ACPD 5, 11029­11054, 2005 Convective gravity waves at mid-latitudes Y. G. Choi et al. Title Page Discussions Wind-profiler observations of gravity waves produced by convection at mid-latitudes Y. G. Choi1­11054, 2005 Convective gravity waves at mid-latitudes Y. G. Choi et al. Title Page Abstract Introduction

  5. Electric and kinematic structure of the Oklahoma mesoscale convective system of 7 June 1989

    NASA Technical Reports Server (NTRS)

    Hunter, Steven M.; Schur, Terry J.; Marshall, Thomas C.; Rust, W. D.

    1992-01-01

    Balloon soundings of electric field in Oklahoma mesoscale convective systems (MCS) were obtained by the National Severe Storms Laboratory in the spring of 1989. This study focuses on a sounding made in the rearward edge of an MCS stratiform rain area on 7 June 1989. Data from Doppler radars, a lightning ground-strike location system, satellite, and other sources is used to relate the mesoscale attributes of the MCS to the observed electric-field profile.

  6. Stability of subsea pipelines during large storms.

    PubMed

    Draper, Scott; An, Hongwei; Cheng, Liang; White, David J; Griffiths, Terry

    2015-01-28

    On-bottom stability design of subsea pipelines transporting hydrocarbons is important to ensure safety and reliability but is challenging to achieve in the onerous metocean (meteorological and oceanographic) conditions typical of large storms (such as tropical cyclones, hurricanes or typhoons). This challenge is increased by the fact that industry design guidelines presently give no guidance on how to incorporate the potential benefits of seabed mobility, which can lead to lowering and self-burial of the pipeline on a sandy seabed. In this paper, we demonstrate recent advances in experimental modelling of pipeline scour and present results investigating how pipeline stability can change in a large storm. An emphasis is placed on the initial development of the storm, where scour is inevitable on an erodible bed as the storm velocities build up to peak conditions. During this initial development, we compare the rate at which peak near-bed velocities increase in a large storm (typically less than 10(-3)?m?s(-2)) to the rate at which a pipeline scours and subsequently lowers (which is dependent not only on the storm velocities, but also on the mechanism of lowering and the pipeline properties). We show that the relative magnitude of these rates influences pipeline embedment during a storm and the stability of the pipeline. PMID:25512592

  7. Has the number of Indian summer monsoon depressions decreased over the last thirty years?

    NASA Astrophysics Data System (ADS)

    Cohen, N. Y.; Boos, W. R.

    2014-12-01

    Precipitation in the summer monsoon season accounts for more than 80% of India's annual rainfall and is crucial for the region's agriculture and economy. A large fraction of this summer precipitation is produced by vortices with outer radii of about 1000 km that typically form over Bay of Bengal. Intense occurrences of these synoptic-scale storms are commonly classified as monsoon depressions. Records of monsoon depression tracks maintained by the India Meteorological Department extend from the late 19th century to the current day, and show an average of about 6 monsoon depressions forming each summer season in the Indian region. Recent analyses of these records have revealed a statistically significant decreasing trend in the number of depressions but an increase in the number of weaker storms since the mid-20th century. In particular, the years 2002, 2010, and 2012 were noted for being the first summers, in over a century, in which no depressions formed. Here satellite and reanalysis datasets are used to document the existence of multiple storms in the summers of 2002, 2010, and 2012 that meet traditional criteria for classification as monsoon depressions. This indicates that the India Meteorological Department record is missing storms, at least in those recent years. We furthermore use ocean surface wind speeds obtained from satellite scatterometers to estimate the number of extreme synoptic events occurring each summer over the Bay of Bengal, and find that this proxy for storm counts exhibits no statistically significant trend over the last three decades. Depression counts based on a reanalysis dataset also exhibit no statistically significant trend over the last three decades, but temporal changes in the observing network may render reanalysis-based storm-count trends unreliable. In summary, our results demonstrate the existence of possible errors in the dataset on which previous claims of large trends in monsoon depression activity have been based. Although multiple issues exist with storm counts based on several reanalysis and satellite datasets, we were unable to find a statistically significant downward trend in depression counts using those datasets. This indicates a need for improved monitoring of monsoon depressions and more in-depth study of possible trends in their activity.

  8. Asian Summer Monsoon Intraseasonal Variability in General Circulation Models

    SciTech Connect

    Sperber, K R; Annamalai, H

    2004-02-24

    The goals of this report are: (1) Analyze boreal summer Asian monsoon intraseasonal variability general circulation models--How well do the models represent the eastward and northward propagating components of the convection and how well do the models represent the interactive control that the western tropical Pacific rainfall exerts on the rainfall over India and vice-versa? (2) Role of air-sea interactions--prescribed vs. interactive ocean; and (3) Mean monsoon vs. variability.

  9. Effects of the solstitial dust storms to the winter polar warmings in the Martian middle atmosphere

    NASA Astrophysics Data System (ADS)

    Kuroda, Takeshi; Medvedev, Alexander; Hartogh, Paul; Takahashi, Masaaki

    2010-05-01

    The planet-encircling dust storms occurring around the northern winter solstice on Mars produce strong winter polar warmings in the middle atmosphere. Such features have been observed by the Viking spacecraft (so-called 1977b storm), and recently by the Mars Climate Sounder onboard the Mars Reconnaissance Orbiter in 2007 and 2009. We have investigated the changes in the meridional circulation during the planet-encircling dust storms which produce such strong temperature inversions using a Martian general circulation model. It is shown that, in the simulation with the dust opacity ?=3 in visible wavelength, the tides, stationary planetary waves (SPW) with the zonal wavenumber s=1, and resolved small-scale gravity waves and eddies are significantly enhanced above the winter hemisphere. They caused vigorous poleward and downward transport, and, consequently, the adiabatic heating. The increase of the tidal forcing is mainly due to a stronger excitation in the summer hemisphere. Contribution of the SPW (s=1) increases during dust storms due to intensified generation in the lower atmosphere as well as due to more favorable vertical propagation. SPW (s=2) varies less with the dust load, dissipates lower, and contributes to the warming only below ~0.1 mb. Transient planetary wave (s=1, period ~5 sols) with a barotropic/baroclinic vertical structure provides up to 1/3 of the forcing by SPW (s=1).

  10. [Summary of Research on Relationship Between Core Convective Structure and Intensity Change in Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The downshear reformation of Tropical Storm Gabrielle (2001) was investigated using radar reflectivity and lightning data that were nearly continuous in time, as well as frequent aircraft reconnaissance flights. Initially the storm was a marginal tropical storm in an environment with strong 850-200 hPa vertical wind shear of 12-13 meters per second and an approaching upper tropospheric trough. Both the observed outflow and an adiabatic balance model calculation showed that the radial-vertical circulation increased with time as the trough approached. Convection was highly asymmetric, with almost all radar return located in one quadrant left of downshear in the storm. Reconnaissance data show that an intense mesovortex formed downshear of the original center. This vortex was located just south of, rather than within, a strong downshear left lightning outbreak, consistent with tilting of the horizontal vorticity associated with the vertical wind shear. The downshear mesovortex contained a 972 hPa minimum central pressure, 20 hPa lower than minimum pressure in the original vortex just three hours earlier. The mesovortex became the new center of the storm, but weakened somewhat prior to landfall. It is argued that dry air carried around the storm from the region of upshear subsidence, as well as the direct effects of the shear, prevented the reformed vortex from continuing to intensify. Despite the subsequent weakening of the reformed center, it reached land with greater intensity than the original center. It is argued that this intensification process was set into motion by the vertical wind shear in the presence of an environment with upward motion forced by the upper tropospheric trough. In addition, the new center formed much closer to the coast and made landfall much earlier than predicted. Such vertical shear-induced intensity and track fluctuations are important to understand, especially in storms approaching the coast. The structures of the highly sheared tropical storm Chantal During CAMEX-4 is also discussed.

  11. Convection compensated electrophoretic NMR.

    PubMed

    He, Q; Wei, Z

    2001-06-01

    A novel method of convection compensated ENMR (CC-ENMR) has been developed to detect electrophoretic motion of ionic species in the presence of bulk solution convection. This was accomplished using a gradient moment nulling technique to remove spectral artifacts from heat-induced convection and using the polarity switch of the applied electric field to retain spin phase modulations due to electrophoretic flow. Experiments were carried out with a mixture of 100 mM L-aspartic acid and 100 mM 4,9-dioxa-1,12-dodecanediamine to demonstrate this new method of ENMR. CC-ENMR enhances our previously developed capillary array ENMR (CA-ENMR) in solving the convection problem. The combined CA- and CC-ENMR approach strengthens the potential of multidimensional ENMR in simultaneous structural determination of coexisting proteins and protein conformations in biological buffer solutions of high ionic strength. Structural mapping of interacting proteins during biochemical reactions becomes possible in the future using ENMR techniques, which may have a profound impact on the understanding of biological events, including protein folding, genetic control, and signal transduction in general. PMID:11384170

  12. Amodifiedshallowwatersystemforinvestigating convective-scaledataassimilation

    E-print Network

    Wirosoetisno, Djoko

    of convective-scale dynamics while remaining computationally inexpensive, thus allowing an extensive: · artificially mimic conditional instabil- ity (positive buoyancy) and the transport of moisture. · contain (heterogeneous background error covariance). 5. Theoretical and numerical aspects The quasi-2D rotating symmetric

  13. Slantwise Convection Case Exercise

    NSDL National Science Digital Library

    COMET

    2002-06-17

    This exercise examines an event that took place in the 24 hour time period beginning at 18Z, Dec 31, 2000 in southern British Columbia, Canada and northern Washington/Idaho, United States. This is a companion piece to the COMET Webcast, Slantwise Convection: An Operational Approach.

  14. NATURAL CONVECTION INPILE LOOP

    Microsoft Academic Search

    Sparrell

    1957-01-01

    A small, natural-convection, NaK-cooled in-pile loop is described. The ; loop has a 3-in. diameter and is 7-ft long. The loop is designed for testing ; small fuel pins at highpower densities. Temperature control in the loop is ; achieved by controlling the coolant flow rate. (T.F.H.);

  15. Magnetic Storms from the Ground: Teacher's Guide

    NSDL National Science Digital Library

    In this activity, students will analyze graphical data to familiarize themselves with the Earth's changing magnetic field. They will discover that coronal mass ejections (CMEs) and other solar storms can buffet the Earth with clouds of charged particles and magnetic fields which will affect the large-scale properties of the Earth's magnetic field and can also be easily detected on the ground. During this activity students will become familiar with the Earth's changing magnetic field through a solar storm plotting activity, analyze graphical data to calculate the percent of change, and plot their information on a map of Canada to determine the areas that are the most susceptible to magnetic storms.

  16. Geomagnetic storm fields near a synchronous satellite.

    NASA Technical Reports Server (NTRS)

    Kawasaki, K.; Akasofu, S. I.

    1971-01-01

    An apparent early recovery of the main phase of geomagnetic storms at the distance of the synchronous satellite is examined in terms of changing electric current distributions in the magnetosphere during magnetic storms. It is suggested that a rapid recession of the edge of the plasma sheet (after the advance toward the earth during an early epoch of the main phase) is partly responsible for the early recovery. Relevant plasma sheet variations during geomagnetic storms are found to be in agreement with the inferred variations.

  17. Nuclear Magnetohydrodynamic EMP, Solar Storms, and Substorms

    E-print Network

    Mario Rabinowitz; A. P. Sakis Meliopoulos; Elias N. Glytsis; George J. Cokkinides

    2003-07-12

    In addition to a fast electromagnetic pulse (EMP), a high altitude nuclear burst produces a relatively slow magnetohydrodynarnic EMP (MHD EMP), whose effects are like those from solar storm geomagnetically induced currents (SS GIC). The MHD EMP electric field E 10^-2 V/m and lasts >10^3 sec. Although the solar storm electric field is lower than MHD EMP, the solar storm effects are generally greater due to their much longer duration. Substorms produce much smaller effects than SS GIC, but occur much more frequently. This paper describes the physics of such geomagnetic disturbances and analyzes their effects.

  18. Convection and the Soil-Moisture Precipitation Feedback

    NASA Astrophysics Data System (ADS)

    Schar, C.; Froidevaux, P.; Keller, M.; Schlemmer, L.; Langhans, W.; Schmidli, J.

    2014-12-01

    The soil moisture - precipitation (SMP) feedback is of key importance for climate and climate change. A positive SMP feedback tends to amplify the hydrological response to external forcings (and thereby fosters precipitation and drought extremes), while a negative SMP feedback tends to moderate the influence of external forcings (and thereby stabilizes the hydrological cycle). The sign of the SMP feedback is poorly constrained by the current literature. Theoretical, modeling and observational studies partly disagree, and have suggested both negative and positive feedback loops. Can wet soil anomalies indeed result in either an increase or a decrease of precipitation (positive or negative SMP feedback, respectively)? Here we investigate the local SMP feedback using real-case and idealized convection-resolving simulations. An idealized simulation strategy is developed, which is able to replicate both signs of the feedback loop, depending on the environmental parameters. The mechanism relies on horizontal soil moisture variations, which may develop and intensify spontaneously. The positive expression of the feedback is associated with the initiation of convection over dry soil patches, but the convective cells then propagate over wet patches, where they strengthen and preferentially precipitate. The negative feedback may occur when the wind profile is too weak to support the propagation of convective features from dry to wet areas. Precipitation is then generally weaker and falls preferentially over dry patches. The results highlight the role of the mid-tropospheric flow in determining the sign of the feedback. A key element of the positive feedback is the exploitation of both low convective inhibition (CIN) over dry patches (for the initiation of convection), and high CAPE over wet patches (for the generation of precipitation). The results of this study will also be discussed in relation to climate change scenarios that exhibit large biases in surface temperature and interannual variability over mid-latitude summer climates, both over Europe and North America. It is argued that parameterized convection may contribute towards such biases by overemphasizing a positive SMP feedback.

  19. Polar vortex formation in giant-planet atmospheres due to moist convection

    NASA Astrophysics Data System (ADS)

    O’Neill, Morgan E.; Emanuel, Kerry A.; Flierl, Glenn R.

    2015-07-01

    A strong cyclonic vortex has been observed on each of Saturn’s poles, coincident with a local maximum in observed tropospheric temperature. Neptune also exhibits a relatively warm, although much more transient, region on its south pole. Whether similar features exist on Jupiter will be resolved by the 2016 Juno mission. Energetic, small-scale storm-like features that originate from the water-cloud level or lower have been observed on each of the giant planets and attributed to moist convection, suggesting that these storms play a significant role in global heat transfer from the hot interior to space. Nevertheless, the creation and maintenance of Saturn’s polar vortices, and their presence or absence on the other giant planets, are not understood. Here we use simulations with a shallow-water model to show that storm generation, driven by moist convection, can create a strong polar cyclone throughout the depth of a planet’s troposphere. We find that the type of shallow polar flow that occurs on a giant planet can be described by the size ratio of small eddies to the planetary radius and the energy density of its atmosphere due to latent heating from moist convection. We suggest that the observed difference in these parameters between Saturn and Jupiter may preclude a Jovian polar cyclone.

  20. The Influence of Aerosols and Environmental Moisture on the Characteristics of Supercellular and Multicellular Deep Convection

    NASA Astrophysics Data System (ADS)

    Grant, L. D.; van den Heever, S. C.

    2013-12-01

    Mechanisms leading to differences between low-precipitation (LP) and classic (CL) supercell storm structure are not well understood, due in part to the small number of observational and modeling studies of LPs that have been reported in the literature. Though LPs and CLs sometimes occur within close proximity, CLs are found under a wider range of environmental conditions. LPs usually form near the dryline or in the high plains of the U.S., and they are typically isolated or upwind relative to surrounding deep convection. Since high aerosol concentrations and dry layers are more likely in these environments, the goal of this research is to investigate the sensitivity of deep convective characteristics, including LP and classic supercells as well as neighboring convection, both to changes in the background aerosol concentrations and environmental moisture profile. The Regional Atmospheric Modeling System (RAMS), configured as a high-resolution cloud-resolving model, was used to achieve this goal. Simulated convection was initiated with a warm thermal perturbation, and subsequent deep convection was simulated under a range of aerosol concentrations and moisture profiles. In the control simulation, which utilized a clean aerosol background and a moist profile, the initial convection splits into a right-mover that becomes a strong and steady classic supercell, and a left-mover that evolves into a multicellular cluster. Sensitivity tests demonstrate that the right-mover becomes an LP supercell under both clean and polluted aerosol concentrations when elevated dry layers are present in the moisture profile. Precipitation characteristics of the left-moving cluster are sensitive both to the aerosol concentrations and the moisture profile. The relative control of aerosols and dry layers on the precipitation characteristics, microphysical processes, and thermodynamics including cold pool forcing, of different dynamically controlled convective storm types within the same domain - namely, CL and LP supercells and multicell clusters - will be presented.

  1. Thermocapillary Convection in Liquid Droplets

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The purpose of this video is to understand the effects of surface tension on fluid convection. The fluid system chosen is the liquid sessile droplet to show the importance in single crystal growth, the spray drying and cooling of metal, and the advance droplet radiators of the space stations radiators. A cross sectional representation of a hemispherical liquid droplet under ideal conditions is used to show internal fluid motion. A direct simulation of buoyancy-dominant convection and surface tension-dominant convection is graphically displayed. The clear differences between two mechanisms of fluid transport, thermocapillary convection, and bouncy dominant convection is illustrated.

  2. Mesoscale convective systems

    NASA Astrophysics Data System (ADS)

    Houze, Robert A.

    2004-12-01

    Mesoscale convective systems (MCSs) have regions of both convective and stratiform precipitation, and they develop mesoscale circulations as they mature. The upward motion takes the form of a deep-layer ascent drawn into the MCS in response to the latent heating and cooling in the convective region. The ascending layer overturns as it rises but overall retains a coherent layer structure. A middle level layer of inflow enters the stratiform region of the MCS from a direction determined by the large-scale flow and descends in response to diabatic cooling at middle-to-low levels. A middle level mesoscale convective vortex (MCV) develops in the stratiform region, prolongs the MCS, and may contribute to tropical cyclone development. The propagation of an MCS may have a discrete component but may further be influenced by waves and disturbances generated both in response to the MCS and external to the MCS. Waves of a larger scale may affect the propagation velocity by phase locking with the MCS in a cooperative mode. The horizontal scale of an MCS may be limited either by a balance between the formation rate of convective precipitation and dissipation of stratiform precipitation or by the Rossby radius of the MCV. The vertical redistribution of momentum by an MCS depends on the size of the stratiform region, while the net vertical profile of heating of the large-scale environment depends on the amount of stratiform rain. Regional variability of the stratiform rain from MCSs affects the large-scale circulation's response to MCS heating.

  3. University of Minnesota StormWaterMasterPlan

    E-print Network

    Minnesota, University of

    University of Minnesota StormWaterMasterPlan TwinCitiesCampus Preparedfor: Storm Water Linkage Committee members University Services leadership 2012 Annual Storm Water Meeting Engineering Company Paul J. Pasko III, PE - SEH for their input on this plan #12; Storm Water Master Plan

  4. ORIGINAL PAPER Surface runoff contribution of nitrogen during storm events

    E-print Network

    TKN concentrations during storm. A storm water sampling program was carried out to gather requisite Ecosystem Management Model for TKN. Water quality and storm flow data collected from January 2000ORIGINAL PAPER Surface runoff contribution of nitrogen during storm events in a forested watershed

  5. Utilize cloud computing to support dust storm forecasting Qunying Huanga

    E-print Network

    Chen, Songqing

    Utilize cloud computing to support dust storm forecasting Qunying Huanga *, Chaowei Yanga , Karl forecasting of dust storms are of significant interest to public health and environment sciences. Dust storms storm forecasting operational system should support a disruptive fashion by scaling up to enable high

  6. Characteristics of Sprite-Producing Positive Cloud-to-Ground Lightning during the 19 July 2000 STEPS Mesoscale Convective Systems

    Microsoft Academic Search

    Walter A. Lyons; Thomas E. Nelson; Earle R. Williams; Steven A. Cummer; Mark A. Stanley

    2003-01-01

    During the summer of 2000, the Severe Thunderstorm Electrification and Precipitation Study (STEPS) program deployed a three-dimensional Lightning Mapping Array (LMA) near Goodland, Kansas. Video confirmation of sprites triggered by lightning within storms traversing the LMA domain were coordinated with extremely low frequency (ELF) transient measurements in Rhode Island and North Carolina. Two techniques of estimating changes in vertical charge

  7. CUSP Summer Enhancement Fellowship-CUSP-ACEC Program Summer 2011 Application CUSP SUMMER ENHANCEMENT FELLOWSHIP

    E-print Network

    Hone, James

    CUSP Summer Enhancement Fellowship-CUSP-ACEC Program Summer 2011 Application CUSP SUMMER ENHANCEMENT FELLOWSHIP AMERICAN COUNCIL OF ENGINEERING COMPANIES OF NEW YORK (ACEC-NY) PROGRAM SUMMER 2011 APPLICATION DEADLINE: FRIDAY, JANUARY 28 TH The CUSP Summer Enhancement Fellowship provides a competitive

  8. Summer 2007 Cellular Concepts

    E-print Network

    Dyer, Bill

    (Bell Labs): 1971 ·First commercial deployment in US: Chicago, 1983 ·A long delay!!! #12;Summer 2007 2007 Various upgrade paths for wireless technologies: move towards data Analog1G #12;Summer 2007 capacity = 277N, 277/208= 1.33 ·Problem: distance between cells using the same frequencies has been reduced

  9. The Summer Stars Program.

    ERIC Educational Resources Information Center

    Cantrell, Mary Lou; Ebdon, Susan Austin; Firlik, Russell; Johnson, Diane; Rearick, Dianne

    1997-01-01

    Designing projects around Gardner's multiple intelligences, a Connecticut school created a one-week summer camp where children can tap into their unique strengths. The Summer Stars program allows children ages 7-12 to choose materials and activities from many topics and to participate in one of three internships involving a discovery museum, a…

  10. Summer Agricultural Program Activities.

    ERIC Educational Resources Information Center

    Swan, Michael K.

    1997-01-01

    Survey responses from 113 of 123 agricultural teacher educators and 48 of 54 state supervisors identified favored summer program activities as update conferences and supervising agriculture experience home projects. They perceived the time allocated to summer activities to be 37-40 days; national consensus is ideally 50 days. (SK)

  11. SUMMER SEMESTER (3 credits)

    E-print Network

    SUMMER SEMESTER (3 credits) General Education Courses: Credit Hours: General Education Courses: Credit Hours: General Education Course: ENGL 110C 3 ENGL 211C, or 221C or 231C 3 Foreign Language I (may 3 SUMMER SEMESTER (3 credits) General Education Courses: Credit Hours: General Education Courses

  12. Intramural Sports Summer 2014

    E-print Network

    Escher, Christine

    Intramural Sports 4v4 Soccer Tournament Summer 2014 Intramural Sports Calendar of Events Summer 2014 Potential League Offerings Men's Women's Co-Rec Sports and Special Programs Office 111 Dixon/Staff/Affiliates with a Recreational Sports Membership are eligible to participate. http://oregonstate.edu/recsports/intramural-sports

  13. Celebrate Summer with Reading

    ERIC Educational Resources Information Center

    Texley, Juliana

    2007-01-01

    School is out and the summer is full of both official and unofficial holidays that prompt us to enjoy science and the profession of sharing it. As in past years, the reviewers and editors of "NSTA Recommends"--ready and willing to share their enthusiasm for reading with you--have been gathering suggestions for the summer. So along with your beach…

  14. School Construction Summer Slam

    ERIC Educational Resources Information Center

    Jensen, Richard F.

    2012-01-01

    Every school has a list of renovations, upgrades and repairs that need attention, but many are too distracting and disruptive to carry out during the school year. Often, the best time to address these nagging construction projects is during the summer when students are on break and the campus is quieter. Although these "summer slammers" often are…

  15. Gravity Waves Generated by Convection: A New Idealized Model Tool and Direct Validation with Satellite Observations

    NASA Astrophysics Data System (ADS)

    Alexander, M. Joan; Stephan, Claudia

    2015-04-01

    In climate models, gravity waves remain too poorly resolved to be directly modelled. Instead, simplified parameterizations are used to include gravity wave effects on model winds. A few climate models link some of the parameterized waves to convective sources, providing a mechanism for feedback between changes in convection and gravity wave-driven changes in circulation in the tropics and above high-latitude storms. These convective wave parameterizations are based on limited case studies with cloud-resolving models, but they are poorly constrained by observational validation, and tuning parameters have large uncertainties. Our new work distills results from complex, full-physics cloud-resolving model studies to essential variables for gravity wave generation. We use the Weather Research Forecast (WRF) model to study relationships between precipitation, latent heating/cooling and other cloud properties to the spectrum of gravity wave momentum flux above midlatitude storm systems. Results show the gravity wave spectrum is surprisingly insensitive to the representation of microphysics in WRF. This is good news for use of these models for gravity wave parameterization development since microphysical properties are a key uncertainty. We further use the full-physics cloud-resolving model as a tool to directly link observed precipitation variability to gravity wave generation. We show that waves in an idealized model forced with radar-observed precipitation can quantitatively reproduce instantaneous satellite-observed features of the gravity wave field above storms, which is a powerful validation of our understanding of waves generated by convection. The idealized model directly links observations of surface precipitation to observed waves in the stratosphere, and the simplicity of the model permits deep/large-area domains for studies of wave-mean flow interactions. This unique validated model tool permits quantitative studies of gravity wave driving of regional circulation and provides a new method for future development of realistic convective gravity wave parameterizations.

  16. Attributes of mesoscale convective systems at the land-ocean transition in Senegal during NASA African Monsoon Multidisciplinary Analyses 2006

    NASA Astrophysics Data System (ADS)

    Delonge, Marcia S.; Fuentes, Jose D.; Chan, Stephen; Kucera, Paul A.; Joseph, Everette; Gaye, Amadou T.; Daouda, Badiane

    2010-05-01

    In this study we investigate the development of a mesoscale convective system (MCS) as it moved from West Africa to the Atlantic Ocean on 31 August 2006. We document surface and atmospheric conditions preceding and following the MCS, particularly near the coast. These analyses are used to evaluate how thermodynamic and microphysical gradients influence storms as they move from continental to maritime environments. To achieve these goals, we employ observations from NASA African Monsoon Multidisciplinary Analyses (NAMMA) from the NASA S band polarimetric Doppler radar, a meteorological flux tower, upper-air soundings, and rain gauges. We show that the MCS maintained a convective leading edge and trailing stratiform region as it propagated from land to ocean. The initial strength and organization of the MCS were associated with favorable antecedent conditions in the continental lower atmosphere, including high specific humidity (18 g kg-1), temperatures (300 K), and wind shear. While transitioning, the convective and stratiform regions became weaker and disorganized. Such storm changes were linked to less favorable thermodynamic, dynamic, and microphysical conditions over ocean. To address whether storms in different life-cycle phases exhibited similar features, a composite analysis of major NAMMA events was performed. This analysis revealed an even stronger shift to lower reflectivity values over ocean. These findings support the hypothesis that favorable thermodynamic conditions over the coast are a prerequisite to ensuring that MCSs do not dissipate at the continental-maritime transition, particularly due to strong gradients that can weaken West African storms moving from land to ocean.

  17. Field Evaluation of Low-E Storm Windows

    SciTech Connect

    Drumheller, S. Craig; Kohler, Christian; Minen, Stefanie

    2007-07-11

    A field evaluation comparing the performance of low emittance (low-e) storm windows with both standard clear storm windows and no storm windows was performed in a cold climate. Six homes with single-pane windows were monitored over the period of one heating season. The homes were monitored with no storm windows and with new storm windows. The storm windows installed on four of the six homes included a hard coat, pyrolitic, low-e coating while the storm windows for the other two homeshad traditional clear glass. Overall heating load reduction due to the storm windows was 13percent with the clear glass and 21percent with the low-e windows. Simple paybacks for the addition of the storm windows were 10 years for the clear glass and 4.5 years forthe low-e storm windows.

  18. Geomagnetic storms, super-storms, and their impacts on GPS-based navigation systems

    NASA Astrophysics Data System (ADS)

    Astafyeva, E.; Yasyukevich, Yu.; Maksikov, A.; Zhivetiev, I.

    2014-07-01

    Using data of GPS receivers located worldwide, we analyze the quality of GPS performance during four geomagnetic storms of different intensity: two super-storms and two intense storms. We show that during super-storms the density of GPS Losses-of-Lock (LoL) increases up to 0.25% at L1 frequency and up to 3% at L2 frequency, and up to 0.15% (at L1) and 1% (at L2) during less intense storms. Also, depending on the intensity of the storm time ionospheric disturbances, the total number of total electron content (TEC) slips can exceed from 4 to 40 times the quiet time level. Both GPS LoL and TEC slips occur during abrupt changes of SYM-H index of geomagnetic activity, i.e., during the main phase of geomagnetic storms and during development of ionospheric storms. The main contribution in the total number of GPS LoL was found to be done by GPS sites located at low and high latitudes, whereas the area of numerous TEC slips seemed to mostly correspond to the boundary of the auroral oval, i.e., region with intensive ionospheric irregularities. Our global maps of TEC slips show where the regions with intense irregularities of electron density occur during geomagnetic storms and will let us in future predict appearance of GPS errors for geomagnetically disturbed conditions.

  19. Dealing with Storm-Damaged Trees 

    E-print Network

    Kirk, Melanie; Taylor, Eric; Foster, C. Darwin

    2005-10-25

    Many homeowners need help caring for or removing damaged trees after a natural disaster. This publication explains what a certified arborist is and how to select one. It also cautions against burning debris downed by a storm....

  20. The semiannual variation of great geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Svalgaard, L.; Cliver, E. W.; Ling, A. G.

    2002-08-01

    The occurrence frequency of the largest geomagnetic storms from 1868-1998 exhibits a well-defined semiannual modulation with more than twice as many storms occurring during equinoctial months than at the solstices. To examine the cause of this seasonal imbalance, we empirically obtained a new geomagnetic index aam that has the same seasonal and Universal Time variation as the am index. In effect, this extends the am index backward in time to 1868. By normalizing the aam time series for ?, the angle between the solar wind flow direction and Earth's dipole, we removed 75% of the amplitude of the six-month wave in monthly averages of aam and ~75% of the seasonal discrepancy in the numbers of great storms. We obtained similar percentages for the (unmodified) am index over the shorter 1959-1998 interval. These results indicate that most, though not all, of the discrepancy in storm counts between the equinoxes and solstices is due to an equinoctial effect.

  1. A History of the Martian Dust Storms

    NASA Astrophysics Data System (ADS)

    McKim, R. J.

    2005-08-01

    The author reviews historical observations of Martian dust storms from the earliest telescopic records up to the present day (see R.J.McKim, Telescopic Martian Dust Storms: A Narrative and Catalogue, Memoirs of the British Astronomical Association, volume 44, 1999 (166 pp)). The earliest record begins with Maraldi in 1704. The term ``yellow cloud" was coined by Burton (1879). The first event which attracted much attention was the regional dust storm of 1894 October-November. The first planet-encircling event was that of 1909. The daily evolution of dust storms began to be studied in 1911; photography would not help until 1922. Other milestones in our understanding of the phenomenon are illustrated and explained. The telescopic literature is littered with errors of fact and interpretation, and the author describes some of the pitfalls and successes in the analysis of old telescopic records.

  2. Tropical Storm Faxai - Duration: 13 seconds.

    NASA Video Gallery

    NASA/JAXA's TRMM Satellite provided data of developing Tropical Storm Faxai to make this 3-D image that showed some towering thunderstorms in the area were reaching altitudes of up to 15.5km/~9.6 m...

  3. Numerical prediction of storm surge around Taiwan

    NASA Astrophysics Data System (ADS)

    Li, H. W.

    2003-04-01

    A numerical model of storm surge is developed to predict the sea level variations due to typhoons approaching Taiwan. The storm surge associating with a typhoon approaching to Taiwan is one of the main causes that floods frequently occur in the low land areas in certain exposed coastlines. Every year typhoons strike Taiwan, especially from June to October. Typhoon surges have caused a lot of catastrophes in the past. The model is based on the hydrodynamical-numerical method. Air pressure gradient and wind stress are considered as the driving forces. A circular storm is taken here as the typhoon model. In this model the bottom topography plays a great role. To verify this numerical model the storm surges due to typhoons approaching Taiwan in 2000 are selected for case studies. In general the computed results agree with the observed data in most tidal gauge stations around Taiwan.

  4. Storm Water Survey Answer Sheet About You

    E-print Network

    California at Santa Cruz, University of

    Physical & Biological Sciences Planning and Budget Social Sciences is not allowed in the storm drains on campus? (Check all that apply) Irrigation water Water flowing from irrigation systems Water flowing from washing vehicles

  5. Nuclear magnetohydrodynamic EMP, solar storms, and substorms

    SciTech Connect

    Rabinowitz, M. (Electric Power Research Inst., Palo Alto, CA (United States)); Meliopoulous, A.P.S.; Glytsis, E.N. (Georgia Inst. of Tech., Atlanta, GA (United States). School of Electrical Engineering); Cokkinides, G.J. (Electrical Engineering Dept., Univ. of South Carolina, Columbia, SC (United States))

    1992-10-20

    In addition to a fast electromagnetic pulse (EMP), a high altitude nuclear burst produces a relatively slow magnetohydrodynamic EMP (MHD EMP), whose effects are like those from solar storm geomagnetically induced currents (SS-GIC). The MHD EMP electric field E [approx lt] 10[sup [minus] 1] V/m and lasts [approx lt] 10[sup 2] sec, whereas for solar storms E [approx gt] 10[sup [minus] 2] V/m and lasts [approx gt] 10[sup 3] sec. Although the solar storm electric field is lower than MHD EMP, the solar storm effects are generally greater due to their much longer duration. Substorms produce much smaller effects than SS-GIC, but occur much more frequently. This paper describes the physics of such geomagnetic disturbances and analyzes their effects.

  6. Transport of forest fire smoke above the tropopause by supercell convection

    NASA Astrophysics Data System (ADS)

    Fromm, Michael D.; Servranckx, René

    2003-05-01

    A recent letter [Fromm et al., 2000] postulated a link between boreal forest fire smoke and observed stratospheric aerosol enhancements in 1998. Therein a case was made that severe convection played a role in the cross-tropopause transport. A similar occurrence of stratospheric aerosol enhancements in the boreal summer of 2001 was the stimulus to investigate the causal mechanism more deeply. Herein, we show a detailed case illustrating the unambiguous creation of a widespread, dense smoke cloud in the upper troposphere and lower stratosphere (UT/LS) by a Canadian forest fire and explosive convection in May 2001. This event is the apparent common point for several downstream stratospheric mystery cloud observations. Implications of this finding and those pertaining to the boreal summer of 1998 are that convection and boreal biomass burning have an under-resolved and under-appreciated impact on the upper troposphere, lower stratosphere, radiative transfer, and atmospheric chemistry.

  7. Seasonal Variations in Survival of Indicator Bacteria in Soil and Their Contribution to Storm-water Pollution

    PubMed Central

    Van Donsel, Dale J.; Geldreich, Edwin E.; Clarke, Norman A.

    1967-01-01

    Survival of a fecal coliform (Escherichia coli) and a fecal streptococcus (Streptococcus faecalis var. liquifaciens) was studied through several years at shaded and exposed outdoor soil plots. Death rates for both organisms were calculated for the different seasons at both sites. The 90% reduction times for the fecal coliform ranged from 3.3 days in summer to 13.4 days in autumn. For the fecal streptococcus, 90% reduction times were from 2.7 days in summer to 20.1 days in winter. During summer, the fecal coliform survived slightly longer than the fecal streptococcus; during autumn, survival was the same; and in spring and winter the fecal streptococcus survived much longer than the fecal coliform. Both organisms were isolated from storm-water runoff collected below a sampling site when counts were sufficiently high in soil. Isolation was more frequent during prolonged rains, lasting up to 10 days, than during short rain storms. There was evidence of aftergrowth of nonfecal coliforms in the soil as a result of temperature and rainfall variations. Such aftergrowth may contribute to variations in bacterial count of storm-water runoff which have no relation to the sanitary history of the drainage area. PMID:16349746

  8. Convective transport over the central United States and its role in regional CO and ozone budgets

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Pickering, Kenneth E.; Dickerson, Russell R.; Ellis, William G., Jr.; Jacob, Daniel J.; Scala, John R.; Tao, Wei-Kuo; Mcnamara, Donna P.; Simpson, Joanne

    1994-01-01

    We have constructed a regional budget for boundary layer carbon monoxide over the central United States (32.5 deg - 50 deg N, 90 deg - 105 deg W), emphasizing a detailed evaluation of deep convective vertical fluxes appropriate for the month of June. Deep convective venting of the boundary layer (upward) dominates other components of the CO budget, e.g., downward convective transport, loss of CO by oxidation, anthropogenic emissions, and CO produced from oxidation of methane, isoprene, and anthropogenic nonmethane hydrocarbons (NMHCs). Calculations of deep convective venting are based on the method pf Pickering et al.(1992a) which uses a satellite-derived deep convective cloud climatology along with transport statistics from convective cloud model simulations of observed prototype squall line events. This study uses analyses of convective episodes in 1985 and 1989 and CO measurements taken during several midwestern field campaigns. Deep convective venting of the boundary layer over this moderately polluted region provides a net (upward minus downward) flux of 18.1 x 10(exp 8) kg CO/month to the free troposphere during early summer. Shallow cumulus and synoptic-scale weather systems together make a comparable contribution (total net flux 16.2 x 10(exp 8) kg CO/month). Boundary layer venting of CO with other O3 precursors leads to efficient free troposheric O3 formation. We estimate that deep convective transport of CO and other precursors over the central United States in early summer leads to a gross production of 0.66 - 1.1 Gmol O3/d in good agreement with estimates of O3 production from boundary layer venting in a continental-scale model (Jacob et al., 1993a, b). On this respect the central U.S. region acts as s `chimney' for the country, and presumably this O3 contributes to high background levels of O3 in the eastern United States and O3 export to the North Atlantic.

  9. A catalog of interplanetary type III storms

    NASA Technical Reports Server (NTRS)

    Kayser, S. E.; Bougeret, J.-L.; Fainberg, J.; Stone, R. G.

    1988-01-01

    A catalog describing the characteristics of all the interplanetary type III storms observed at kilometric wavelengths by the radio astronomy experiment on the ISEE-3 spacecraft between September 1978 and October 1982 is presented. Three-dimensional trajectories have been determined for about one-third of these storms using radio techniques. Solar coordinate and solar wind parameters derived from the trajectories are also tabulated. A statistical summary of the data is included.

  10. Nowcasting of a supercell storm with VERA

    Microsoft Academic Search

    Stefan Schneider; Barbara Chimani; Hildegard Kaufmann; Benedikt Bica; Christoph Lotteraner; Simon Tschannett; Reinhold Steinacker

    2008-01-01

    On 13th May 2003, a severe weather event took place in Vienna, located in the eastern part of Austria at the foothills of\\u000a the Alps. A supercell storm was reported by storm chasers, including a tornado, large hail and flash floods due to heavy precipitation,\\u000a causing damage to both people and to goods in parts of Vienna downtown, which is

  11. Dust Storm, Red Sea and Saudi Arabia

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Outlined against the dark blue water of the Red Sea, a prominent dust storm is making its way across the Red Sea into Saudi Arabia (22.0N, 39.0E) between the Islamic holy cities of Medinah and Mecca. Funneled through a gap in the coastal ranges of southern Sudan near the Ethiopian border, dust storms frequently will blow counter to the prevailing tropical easterly winds of the region.

  12. Evidence for Ammonia and Water Ices as the Primary Components of Cloud Particles in Saturn's Great Storm of 2010-2011

    NASA Astrophysics Data System (ADS)

    Sromovsky, Lawrence A.; Baines, K. H.; Fry, P. M.

    2013-10-01

    Saturn's Great Storm of 2010-2011 was a major convective eruption that lofted deep atmospheric aerosols up to the visible cloud tops, providing a rare view of normally hidden materials produced at great depths. These materials produce absorption near 3 microns, which is not seen on Saturn outside of storm regions. We used near-infrared spectra of the storm, obtained by the Visual and Infrared Mapping Spectrometer on the Cassini orbiter, to constrain the composition of the cloud particles. We found compelling evidence that the storm cloud contains a multi-component aerosol population comprised primarily of ammonia ice, with water ice the best-defined secondary component. The most likely third component is ammonium hydrosulfide or some weakly absorbing material similar to what dominates visible clouds outside the storm region. Horizontally heterogeneous cloud models favor ammonium hydrosulfide as the third component, while horizontally uniform models favor the weak absorber. Both models rely on water ice absorption to compensate for residual spectral gradients produced by ammonia ice from 3.0 microns to 3.1 microns and need the relatively conservative third component to fill in the sharp ammonia ice absorption peak near 2.96 microns. The best heterogeneous model has spatial coverage fractions of 55% ammonia ice, 22% water ice, and 23% ammonium hydrosulfide. The best homogeneous model has an optically thin layer of weakly absorbing particles above an optically thick layer of water ice particles coated by ammonia ice. These Cassini data provide the first spectroscopic evidence of water ice in Saturn's atmosphere. The presence of water ice in this major storm supports the hypothesis that these convective storms are powered by condensation of water and originate in the 10-20 bar depths of Saturn. This research was supported by NASA's Outer Planets Research Program under grant NNX11AM58G.

  13. Genesis of Typhoon Nari (2001) from a mesoscale convective system

    NASA Astrophysics Data System (ADS)

    Zhang, Da-Lin; Tian, Liqing; Yang, Ming-Jen

    2011-12-01

    In this study, the origin and genesis of Typhoon Nari (2001) as well as its erratic looping track, are examined using large-scale analysis, satellite observations, and a 4 day nested, cloud-resolving simulation with the finest grid size of 1.33 km. Observational analysis reveals that Nari could be traced 5 days back to a diurnally varying mesoscale convective system with growing cyclonic vorticity and relative humidity in the lower troposphere and that it evolved from a mesoscale convective vortex (MCV) as moving over a warm ocean under the influence of a subtropical high, a weak westerly baroclinic disturbance, an approaching-and-departing Typhoon Danas to the east, and the Kuroshio Current. Results show that the model reproduces the genesis, final intensity, looping track, and the general convective activity of Nari during the 4 day period. It also captures two deep subvortices at the eye-eyewall interface that are similar to those previously observed, a few spiral rainbands, and a midget storm size associated with Nari's relatively dry and stable environment. We find that (1) continuous convective overturning within the MCV stretches the low-level vorticity and moistens a deep mesoscale column that are both favorable for genesis; (2) Nari's genesis does not occur until after the passage of the baroclinic disturbance; (3) convective asymmetry induces a smaller-sized vortex circulation from the preexisting MCV; (4) the vortex-vortex interaction with Danas leads to Nari's looping track and temporal weakening; and (5) midlevel convergence associated with the subtropical high and Danas accounts for the generation of a nearly upright eyewall.

  14. Convective Lyapunov spectra

    NASA Astrophysics Data System (ADS)

    Kenfack Jiotsa, Aurélien; Politi, Antonio; Torcini, Alessandro

    2013-06-01

    We generalize the concept of the convective (or velocity-dependent) Lyapunov exponent from the maximum rate ?(v) to an entire spectrum ?(v, n). Our results are derived by following two distinct computational protocols: (i) Legendre transform within the chronotopic approach (Lepri et al 1996 J. Stat. Phys. 82 1429); (ii) by letting evolve an ensemble of initially localized perturbations. The two approaches turn out to be mutually consistent. Moreover, we find the existence of a phase transition: above a critical value n = nc of the integrated density of exponents, the zero-velocity convective exponent is strictly smaller than the corresponding Lyapunov exponent. This phenomenon is traced back to a change of concavity of the so-called temporal Lyapunov spectrum for n > nc, which, therefore, turns out to be a dynamically invariant quantity. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Lyapunov analysis: from dynamical systems theory to applications’.

  15. Eulerian and Lagrangian correlation structures of convective rainstorms

    NASA Astrophysics Data System (ADS)

    May, Don R.; Julien, Pierre Y.

    1998-10-01

    The Eulerian and Lagrangian correlation structures of 13 convective rainstorms were investigated using rainfall data from the 1987 Convective Initiation Downburst Experiment in Denver, Colorado. One minute rainfall data were available for two superposed raingage networks: 46 raingages on the portable automated mesonet (PAM) network at a mean spacing of 10.6 km and 31 additional raingages on the Federal Aviation Administration Lincoln Laboratory Operational Weather Studies (FLOWS) network at a mean spacing of 2.4 km. Eulerian correlation coefficients are low and often negative for high-resolution 1 min rainfall data. Correlation increases with time-averaging, beyond 10-15 min for single rain cells on the FLOWS network and small-mesoscale rainstorms on the PAM network. The average speed of rain cells and small-mesoscale rainstorms was found to be 76.5 and 56.4 km hr-1, respectively. Storm kinematic is identified as the cause of data scatter and low Eulerian correlations. Convective rainstorms are essentially uncorrelated in the Eulerian reference frame at a typical raingage spacing of 2-3 km for rain cells and 10-15 km for small mesoscale rainstorms. A spatial cross-correlation analysis in a Lagrangian reference frame moving with the center of mass of the storm separates the kinematic component from the structural component of a rainfall field. The spatial cross correlations in the Lagrangian rainfall field show considerable improvement over the Eulerian spatial correlation plots, and data scatter is greatly reduced. The increase in correlation coefficients from Eulerian to Lagrangian reference frames typically ranged from 0.5 to 1.1.

  16. Convection to Perfection

    NSDL National Science Digital Library

    2012-08-03

    This demonstration allows students to visualize how heat moves through convection - using water, food coloring, a small cup and a large jar - and prompts them to make a connection between the observed process and cloud formation. The resource is part of the teacher's guide accompanying the video, NASA SCI Files: The Case of the Phenomenal Weather. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

  17. A case study of the impact of boreal summer intraseasonal oscillations on Yangtze rainfall

    NASA Astrophysics Data System (ADS)

    Li, Jianying; Mao, Jiangyu; Wu, Guoxiong

    2015-05-01

    The impact on Yangtze rainfall of the boreal summer intraseasonal oscillations (BSISOs) over the entire Asian summer monsoon region during summer 1996 was investigated using the APHRODITE gridded rainfall and the NCEP-DOE reanalysis II products. Wavelet analyses suggest that the ISOs of Yangtze rainfall were regulated mainly by both 30-60- and 10-25-day oscillations, respectively linked to BSISO1 and BSISO2 activity. Phase locking of the wet phases of these two ISOs resulted in a prolonged wet episode from late June to mid-July. The circulation evolution of the BSISO1 mode showed that active convection accompanied by strong convergence of anomalous zonal winds first developed over the equatorial Indian Ocean, with suppressed convection over the South China Sea (SCS)-Philippine Sea and with active convection over the Yangtze Basin. The triple convection anomaly that aligned meridionally in the East Asian sector arose from a local meridional-vertical cell associated with a Rossby wave-like coupled circulation-convection system. The opposite flow patterns occurred during the dry phase of Yangtze rainfall. The composite BSISO2 cases demonstrated a weak convective anomaly initially appeared around the Maritime Continent, with a huge anomalous anticyclone accompanied by suppressed convection over the SCS-Philippine Sea. The low-level convergence of the anomalous southwesterlies on the northwestern side of the anticyclone and the consequent ascent led to positive rainfall anomalies over the Yangtze Basin. When the entire SCS was dominated by an anomalous cyclone resulting from interaction with upstream systems, convection over the Yangtze Basin was suppressed.

  18. Processes driving storm-scale coastal change along the Outer Banks, North Carolina: Insights from during-storm observations using CLARIS (Invited)

    Microsoft Academic Search

    K. L. Brodie

    2010-01-01

    Storm-scale coastal change is traditionally observed using ``pre-'' and ``post''-storm surveys, making explicit observations of processes driving alongshore variability in erosion and accretion during the storm difficult. Anecdotal evidence suggests that at least during moderate storms, such as the frequent extratropical storms that batters the Outer Banks of North Carolina, significant amounts of recovery may occur while the storm continues

  19. Polarimetric signatures indicative of severe storm development - the Pentecost event 2014

    NASA Astrophysics Data System (ADS)

    Troemel, Silke; Diederich, Malte; Evaristo, Raquel; Ryzhkov, Alexander; Simmer, Clemens

    2015-04-01

    The 2014 Pentecost weekend storms in Europe were a series of severe supercell storms which followed a heatwave in early June 2014, resulting from a Spanish plume synoptic weather pattern. Outbreaks of severe weather were reported from these storm developments with the worst damages occurring over the German state of North Rhine-Westphalia on 9 June, where the storm was described as one of the most violent in decades by the German weather service (DWD). During this event six fatalities, wind gusts up to 150km/h, hail and a flash flood in Düsseldorf has been reported. Monitoring and analysis of high-impact weather using weather radars of shorter wavelength (X- and C-bands) requires special methods, i.e. anomalous high attenuation and differential attenuation due to very large raindrops originating from melting large hail has to be investigated and corrected. During the Pentecost event a record breaking ZDR bias of up to -25dB has been observed. Different strategies for reliable attenuation correction and rainfall estimation for this extreme event are explored and will be presented. A national 3D composite of polarimetric moments covering Germany with 1km horizontal, 250m vertical, and 5 minutes temporal resolution has been generated. 10 C-band radars from the DWD radar network, recently upgraded to polarimetry, have been included. Meanie3D, a 3D scale space tracking algorithm, is applied to the composite to investigate the magnitudes and temporal development of the 3 fundamental steps of a storms lifecycle: 1) high values of differential reflectivity ZDR aloft first indicate a developing cell, 2) ZDR-columns (these are vertical columns of high differential reflectivity) then indicate the updraft zone of a cell in the mature state. The vertical extent of the ZDR-column is thus a measure of the strength of the updraft and for the ensuing rainfall enhancement. 3) The very first big drops reach the surface before the most intense rain begins. This is reflected by the polarimetric fingerprint for differential sedimentation. While preliminary correlation analysis of moderate storms hints at a lag-time between updraft strength and rainfall of 5-10 minutes, the case study on hand suggest increasing lead time depending on the strength of the storm. Magnitudes of ZDR enhancements associated with convective updrafts and differential sedimentation and associated lead times for the Pentecost event will be presented.

  20. The Solar Convection Spectrum

    NASA Technical Reports Server (NTRS)

    Bachmann, Kurt T.

    2000-01-01

    I helped to complete a research project with NASA scientists Dr. David Hathaway (my mentor), Rick Bogart, and John Beck from the SOHO/SOI collaboration. Our published paper in 'Solar Physics' was titled 'The Solar Convection Spectrum' (April 2000). Two of my undergraduate students were named on the paper--Gavrav Khutri and Josh Petitto. Gavrav also wrote a short paper for the National Conference of Undergraduate Research Proceedings in 1998 using a preliminary result. Our main result was that we show no evidence of a scale of convection named 'mesogranulation'. Instead, we see only direct evidence for the well-known scales of convection known as graduation and supergranulation. We are also completing work on vertical versus horizontal flow fluxes at the solar surface. I continue to work on phase relationships of solar activity indicators, but I have not yet written a paper with my students on this topic. Along with my research results, I have developed and augmented undergraduate courses at Birmingham-Southern College by myself and with other faculty. We have included new labs and observations, speakers from NASA and elsewhere, new subject material related to NASA and space science. I have done a great deal of work in outreach, mostly as President and other offices in the Birmingham Astronomical Society. My work includes speaking, attracting speakers, giving workshops, and governing.

  1. Convection in Neptune's magnetosphere

    NASA Technical Reports Server (NTRS)

    Hill, T. W.; Dessler, A. J.

    1990-01-01

    It is assumed that nonthermal escape from Triton's atmosphere produces a co-orbiting torus of unionized gas (presumably nitrogen and hydrogen) that subsequently becomes ionized by electron impact to populate a partial Triton plasma torus analogous to the Io plasma torus in Jupiter's magnetosphere. Centrifugal and magnetic-mirror forces confine the ions to a plasma sheet located between the magnetic and centrifugal equators. The ionization rate, and hence the torus ion concentration, is strongly peaked at the two points (approximately 180 deg apart in longitude) at which Triton's orbit intersects the plasma equator. During the course of Neptune's rotation these intersection points trace out two arcs roughly 75 deg in longitudinal extent, which we take to be the configuration of the resulting (partial) plasma torus. The implied partial ring currents produce a quadrupolar (four-cell) convection system that provides rapid outward transport of plasma from the arcs. Ring-current shielding, however, prevents this convection system from penetrating very far inside the plasma-arc distance. It is suggested that this convection/shielding process accounts for the radial confinement of trapped particles (150 keV or greater) within L = 14.3 as observed by the Voyager LECP instrument.

  2. Potential indirect effects of aerosol on tropical cyclone intensity: convective fluxes and cold-pool activity

    NASA Astrophysics Data System (ADS)

    Krall, G. M.; Cottom, W. R.

    2012-01-01

    Observational and model evidence suggest that a 2008 Western Pacific typhoon (NURI) ingested elevated concentrations of aerosol as it neared the Chinese coast. This study uses a regional model with two-moment bin-emulating microphysics to simulate the typhoon as it enters the field of elevated aerosol concentrations. A clean maritime field of cloud condensation nuclei (CCN) was prescribed as marine background CCN concentrations and then based on satellite and global aerosol model output, increased to pollution levels and further enhanced in sensitivity tests. The typhoon was simulated for 96 h beginning 17 August 2008. During the final 60 h CCN concentrations were enhanced as it neared the Philippines and coastal China. The model was initialized with both global reanalysis model data and irregularly spaced dropsonde data from the 2008 T-PARC observational campaign using an objective analysis routine. At 36 h, the internal nudging of the model was switched off and allowed to freely evolve on its own. As the typhoon encountered the elevated CCN in the sensitivity tests, a significant perturbation of windspeed, convective fluxes, and hydrometeor species behavior was simulated. Early during the ingestion of enhanced CCN, precipitation was reduced due to suppressed collision and coalescence, and storm winds increased in strength. Subsequently, owing to reduced fall speeds of the smaller drops, greater amounts of condensate were thrust into supercooled levels where the drops froze releasing greater amounts of latent heat of freezing. Convection thereby intensified which resulted in enhanced rainfall and more vigorous convectively-produced downdrafts. As the convection intensified in the outer rainbands the storm drifted over the developing cold-pools. The enhanced cold-pools blocked the inflow of warm, moist air into the core of the typhoon which led to a weakening of the typhoon with significantly reduced low level wind speeds. The very high amounts of pollution aerosols resulted in large amounts of condensate being thrust into the storm anvil which weakened convective downdrafts and cold-pools, yet the system did show reductions in windspeed (although weaker) compared with the clean control run. This study suggests that ingestion of elevated amounts of CCN into a tropical cyclone (TC) can appreciably alter the intensity of the storm. This implies that intensity prediction of TCs would be improved by including indirect aerosol affects. However, the pollution aerosols have very little impact on the storm track.

  3. Making Summer Count: How Summer Programs Can Boost Children's Learning

    ERIC Educational Resources Information Center

    McCombs, Jennifer Sloan; Augustine, Catherine; Schwartz, Heather; Bodilly, Susan; McInnis, Brian; Lichter, Dahlia; Cross, Amanda Brown

    2012-01-01

    During summer vacation, many students lose knowledge and skills. By the end of summer, students perform, on average, one month behind where they left off in the spring. Participation in summer learning programs should mitigate learning loss and could even produce achievement gains. Indeed, educators and policymakers increasingly promote summer

  4. Autism Summer School: Alumni Report Project: Autism Summer School

    E-print Network

    Burton, Geoffrey R.

    Autism Summer School: Alumni Report 1 Project: Autism Summer School Title: Report to the Alumni.02.2014 #12;Autism Summer School: Alumni Report 2 Background to Autism Summer School Transition to further education presents challenges for many students, but particularly for those with more complex needs. Autism

  5. Simulating deep convection with a shallow convection scheme

    NASA Astrophysics Data System (ADS)

    Hohenegger, Cathy; Bretherton, Christopher S.

    2010-05-01

    Atmospheric convection profoundly affects the global energy and water balance of our planet by the release of latent heat and the transport of momentum, heat and moisture. However, adequately simulating convection and its effects both over the tropics and mid-latitude continental areas remains a challenge for global climate models. This study uses large-eddy simulations (LES) and single column model experiments to assess the suitability and performance of a shallow convection scheme in simulating deep convection. Cases of mid-latitude summertime continental convection (from the Southern Great Plain ARM measurement facility) and of tropical oceanic convection (from the KWAJEX measurement campaign) are considered. Without any modification the shallow convection scheme provides a better precipitation diurnal cycle but strongly underestimates the precipitation amounts as compared to a deep convection scheme (Zhang-McFarlane scheme) and to the LES. By additionally tying the mixing rates and the cumulus base mass flux to precipitation evaporation as suggested by the LES results, it is nevertheless found that the scheme outperforms the Zhang-McFarlane parameterization: Precipitation amounts and diurnal cycle are better captured both for KWAJEX and ARM, while biases in the temperature and humidity profiles are generally reduced. The main advantage of this approach lies in the fact that the same scheme can be used to simulate shallow and deep convection and their transitional forms.

  6. Is There Evidence of Convectively Injected Water Vapor in the Lowermost Stratosphere Over Boulder, Colorado?

    NASA Astrophysics Data System (ADS)

    Hurst, D. F.; Rosenlof, K. H.; Davis, S. M.; Hall, E. G.; Jordan, A. F.

    2014-12-01

    Anderson et al. (2012) reported the frequent presence of convectively injected water vapor in the lowermost stratosphere over North America during summertime, based on aircraft measurements. They asserted that enhanced catalytic ozone destruction within these wet stratospheric air parcels presents a concern for UV dosages in populated areas, especially if the frequency of deep convective events increases. Schwartz et al.(2013) analyzed 8 years of more widespread Aura Microwave Limb Sounder (MLS) measurements of lower stratospheric water vapor over North America and concluded that anomalously wet (>8 ppm) air parcels were present only 2.5% of the time during July and August. However, given the 3-km vertical resolution of MLS water vapor retrievals in the lowermost stratosphere, thin wet layers deposited by overshooting convection may be present but not readily detectable by MLS. Since 1980 the balloon-borne NOAA frost point hygrometer (FPH) has produced nearly 400 high quality water vapor profiles over Boulder, Colorado, at 5-m vertical resolution from the surface to the middle stratosphere. The 34-year record of high-resolution FPH profiles obtained over Boulder during summer months is evaluated for evidence of convectively injected water vapor in the lowermost stratosphere. A number of approaches are used to assess the contributions of deep convection to the Boulder stratospheric water vapor record. The results are compared to those based on MLS profiles over Boulder and the differences are discussed. Anderson, J. G., D. M. Wilmouth, J. B. Smith, and D. S. Sayres (2012), UV dosage levels in summer: Increased risk of ozone loss from convectively injected water vapor, Science, 337(6096), 835-839, doi:10.1126/science.1222978. Schwartz, M. J., W. G. Read, M. L. Santee, N. J. Livesey, L. Froidevaux, A. Lambert, and G. L. Manney (2013), Convectively injected water vapor in the North American summer lowermost stratosphere, Geophys. Res. Lett., 40, 2316-2321, doi:10.1002/grl.50421.

  7. What caused the cool summer over northern Central Asia, East Asia and central North America during 2009?

    E-print Network

    Wang, Bin

    . 2012 Environ. Res. Lett. 7 044015 (http://iopscience.iop.org/1748-9326/7/4/044015) Download details: IP Address: 121.145.181.3 The article was downloaded on 27/10/2012 at 01:45 Please note that terms the Western North Pacific summer monsoon region. It is also noted that enhanced storm track activity

  8. The Relationship of Tropical Cyclone Convective Intensity to Passive Microwave Observations

    NASA Technical Reports Server (NTRS)

    Hood, Robbie E.; Guillory, Anthony; LaFontaine, Frank J.; Cecil, Dan; Heymsfield, Gerald; Arnold, James E. (Technical Monitor)

    2002-01-01

    During the 1998 and 2001 hurricane seasons, the Advanced Microwave Precipitation Radiometer (AMPR) was flown aboard the National Aeronautics and Space Administration (NASA) ER-2 high altitude aircraft as part of the Third Convection And Moisture EXperiment (CAMEX-3) and the Fourth Convection And Moisture Experiment (CAMEX-4). Several hurricanes and tropical storms were sampled during these experiments. The passive microwave observations of these tropical cyclones collected at frequencies of 10.7, 19.35, 37.1, and 85.5 GHz will be presented to explain differences in precipitation features of the hurricanes. In particular, the relationship of the passive microwave signatures of precipitation-sized ice to vertical updraft strength will be examined as a possible indicator of future convective intensity. Correlated aircraft radar, lightning, visible and infrared information will also be examined to provide further insight.

  9. Diagnosing Vertical Velocity from CloudSat in Deep Tropical Convection

    NASA Astrophysics Data System (ADS)

    Mcgee, C. J.; van den Heever, S. C.; Luo, Z. J.

    2011-12-01

    Deep convective cores in the tropics known as "hot towers" represent a significant contribution to the global atmospheric energy transport in the Hadley circulation. Understanding the dynamic and thermodynamic processes within hot towers is important to the representation of deep convection in global circulation models. One resource by which understanding may be improved is through the use of CloudSat, a member of the A-Train Constellation. The Cloud Profiling Radar (CPR) on CloudSat offers a unique perspective by taking vertical cross-sections of radar reflectivity in all types of clouds. Cross-sections are particularly useful in understanding the structure of deep convection since they identify features such as the reflectivity core, the echo top height, and the depth of the stratiform anvil. This study explores possible relationships between vertical velocity and CloudSat reflectivity fields for isolated hot towers through the use of cloud-resolving model simulations. These simulations are performed with the Regional Atmospheric Modeling System (RAMS). Each simulation is run at 500 meter grid spacing and is initialized with a warm and moist bubble in the boundary layer. These high-resolution simulations are a series of sensitivity tests along varying magnitudes of deep vertical wind shear, bubble temperature perturbation, and bubble moisture perturbation. The simulations are initialized with a Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment (TOGA COARE) sounding representative of the tropical environment. Model output from each simulation is processed using QuickBeam (Haynes et al. 2007), a CloudSat simulator, to produce the simulated reflectivity. The reflectivity fields are then statistically compared to vertical velocity output. It is seen that the updraft intensity increases as the storm gets deeper, up to the point when the storm hits the tropopause and spreads out laterally. There is a positive correlation between the depth of the storm and vertical velocity, providing that the storm is still developing. Thus there is the need to develop a life stage metric that identifies whether or not the storm is developing; this method must rely on instantaneous reflectivity fields alone. For a great majority of time steps, there is a reversal in the gradient of the reflectivity values with increasing height above the core if and only if that time step is later than the one with the highest vertical velocity. Thus we classify the storm as "developing" if the gradient does not reverse above the core, and "dissipating" if it does. This classification appropriately constrains diagnosis of vertical velocity to reflectivity fields that are "developing". For time steps that are "developing", the slope and intercept of the function relating vertical velocity and storm depth allow a quantitative diagnosis of the vertical velocity.

  10. Layered Thermohaline Convection in Hypersaline Geothermal Systems

    Microsoft Academic Search

    Curtis M. Oldenburg; Karsten Pruess

    1998-01-01

    Thermohaline convection occurs in hypersaline geothermal systems due to thermal and salinity effects on liquid density. Because of its importance in oceanography, thermohaline convection in viscous liquids has received more attention than thermohaline convection in porous media. The fingered and layered convection patterns observed in viscous liquid thermohaline convection have been hypothesized to occur also in porous media. However, the

  11. MS, AIP, Sternphysik, 2001 Hydrodynamical Convection Models

    E-print Network

    c MS, AIP, Sternphysik, 2001 Hydrodynamical Convection Models -- Sun and Betelgeuse -- Matthias Steffen Convection is a universal feature in astrophysics, essentially all types of stars have one or even several convection zones. The role of stellar convection is far­reaching: Convective energy transport

  12. Self-organized criticality in tropical convection?

    E-print Network

    Plant, Robert

    Self-organized criticality in tropical convection? Bob Plant Climate Thermodynamics Workshop 22nd picture of tropical convection What is self-organized criticality? Evidence for SOC in convection 1st attempt at SOC model of convection No conclusions, just open questions SOC in tropical convection? ­ p.1

  13. Balloon-borne electric field and microphysics measurements in the 29-30 May 2012 supercell storm in Oklahoma during DC3

    NASA Astrophysics Data System (ADS)

    Waugh, S.; Ziegler, C.; MacGorman, D. R.; Biggerstaff, M. I.; DiGangi, E.

    2013-12-01

    During May-June 2012, the National Severe Storms Laboratory in-storm ballooning team flew balloon-borne instruments into thunderstorms in Oklahoma and Texas during the Deep Convective Clouds and Chemistry Experiment (DC3) field campaign. The balloon-borne instruments consisted of a standard Vaisala RS92-SGP radiosonde to measure location and standard thermodynamic variables, an electric field meter (EFM) to measure the vector electric field, and a particle imager to measure the particle size distribution. The purpose of the particle imager was to provide verification data for model microphysics and for hydrometeor classification schemes of polarimetric radars, as well as to provide data needed to improve understanding of storm electrification processes. Additional measurements made in the Oklahoma-Texas venue of DC3 included mobile environmental soundings, mobile mesonets, three mobile radars, and the Oklahoma and West Texas Lightning Mapping Arrays. On 29-30 May 2012, several supercell storms occurred in central Oklahoma and produced extraordinary lightning flash rates. One of these storms was sampled by DC3 aircraft and by the ground-based systems described above. In particular, a balloon carried an EFM and a particle imager up to approximately 375 mb before being struck by lightning. This paper presents the particle size distributions for various types of particles relative to the lightning, electric field, and kinematic structure of the 29 May storm on which DC3 focused.

  14. The StoRM Certification Process

    NASA Astrophysics Data System (ADS)

    Ronchieri, Elisabetta; Dibenedetto, Michele; Zappi, Riccardo; Dal Pra, Stefano; Aiftimiei, Cristina; Traldi, Sergio

    2011-12-01

    StoRM is an implementation of the SRM interface version 2.2 used by all Large Hadron Collider (LHC) experiments and non-LHC experiments as SRM endpoint at different Tiers of Worldwide LHC Computing Grid. The complexity of its services and the demand of experiments and users are increasing day by day. The growing needs in terms of service level by the StoRM users communities make it necessary to design and implement a more effective testing procedure to quickly and reliably validate new StoRM candidate releases both in code side (for example via test units, and schema valuator) and in final product software (for example via functionality tests, and stress tests). Testing software service is a very critical quality activity performed in a very ad-hoc informal manner by developers, testers and users of StoRM up to now. In this paper, we describe the certification mechanism used by StoRM team to increase the robustness and reliability of the StoRM services. Various typologies of tests, such as quality, installation, configuration, functionality, stress and performance, defined on the base of a set of use cases gathered as consequence of the collaboration among the StoRM team, experiments and users, are illustrated. Each typology of test is either increased or decreased easily from time to time. The proposed mechanism is based on a new configurable testsuite. This is executed by the certification team, who is responsible for validating the release candidate package as well as bug fix (or patch) package, given a certain testbed that considers all possible use cases. In correspondence of each failure, the package is given back to developers waiting for validating a new package.

  15. Global Storm Surge Forecasting and Information System

    NASA Astrophysics Data System (ADS)

    Buckman, Lorraine; Verlaan, Martin; Weerts, Albrecht

    2015-04-01

    The Global Storm Surge Forecasting and Information System is a first-of-its-kind operational forecasting system for storm surge prediction on a global scale, taking into account tidal and extra-tropical storm events in real time. The system, built and hosted by Deltares, provides predictions of water level and surge height up to 10 days in advance from numerical simulations and measurement data integrated within an operational IT environment. The Delft-FEWS software provides the operational environment in which wind forecasts and measurement data are collected and processed, and serves as a platform from which to run the numerical model. The global Delft3D model is built on a spherical, flexible mesh with a resolution around 5 km in near-shore coastal waters and an offshore resolution of 50 km to provide detailed information at the coast while limiting the computational time required. By using a spherical grid, the model requires no external boundary conditions. Numerical global wind forecasts are used as forcing for the model, with plans to incorporate regional meteorological forecasts to better capture smaller, tropical storms using the Wind Enhanced Scheme for generation of tropical winds (WES). The system will be automated to collect regional wind forecasts and storm warning bulletins which are incorporated directly into the model calculations. The forecasting system provides real-time water level and surge information in areas that currently lack local storm surge prediction capability. This information is critical for coastal communities in planning their flood strategy and during disaster response. The system is also designed to supply boundary conditions for coupling finer-scale regional models. The Global Storm Surge Forecasting and Information System is run within the Deltares iD-Lab initiative aiming at collaboration with universities, consultants and interested organizations. The results of the system will be made available via standards such as netCDF-CF, OpenDAP, WaterML2 and/or JSON REST as an interoperability experiment.

  16. Contrasting Characteristics between the Northward and Eastward Propagation of the Intraseasonal Oscillation during the Boreal Summer

    Microsoft Academic Search

    Huang-Hsiung Hsu; Chun-Hsiung Weng; Cheng-Han Wu

    2004-01-01

    This study investigates the structural and evolutionary characteristics of the eastward- and northward-propagating intraseasonal oscillation (ISO) in the Indian Ocean and western Pacific during the boreal summer. Along the equator, the near-surface moisture convergence located to the east of the deep convection region appears to result in the eastward propagation of the ISO, consistent with the frictional wave CISK (conditional

  17. What is the Relationship between the Solar Wind and Storms/Substorms?

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.; Burlaga, L. F.

    1999-01-01

    The interplanetary magnetic field (IMF) carried past the Earth by the solar wind has long been known to be the principal quantity that controls geomagnetic storms and substorms. Intervals of strong southward IMF with durations of at least a significant fraction of a day produce storms, while more typical, shorter intervals of less-intense southward fields produce substorms. The strong, long-duration southward fields are generally associated with coronal mass ejections and magnetic clouds or else they are produced by interplanetary dynamics initiated by fast solar wind flows that compress preexisting southward fields. Smaller, short-duration southward fields that occur on most days are related to long period waves, turbulence, or random variations in the IMF. Southward IMF enhances dayside reconnection between the IMF and the Earth's dipole with the reconnected field lines supplementing open field lines of the geomagnetic tail and producing an expanded polar cap and increased tail energy. Although the frequent storage of solar wind energy and its release during substorms is the most common mode of solar wind/magnetosphere interaction, under certain circumstances, steady southward IMF seems to produce intervals of relatively steady magnetosphere convection without substorms. During these latter times, the inner magnetosphere remains in a stressed tail-like state while the more distant magnetotail has larger northward field and more dipolar-like field lines. Recent evidence suggests that enhanced magnetosphere particle densities associated with enhanced solar wind densities allow more particles to be accelerated for the ring current, thus creating larger storms.

  18. Compressional acceleration of energetic particles driven by magnetospheric convection

    NASA Astrophysics Data System (ADS)

    Zhang, M.

    Based on a quasilinear method developed for cosmic ray studies we have established a magnetospheric particle transport equation in the phase space of location and momentum This new particle transport theory differs from the conventional theory using canonical variables by taking into account the effect of large-scale electric field that drives the magnetospheric convection The new transport equation now includes essentially all the basic particle transport mechanisms streaming convection drift focusing adiabatic energy change acceleration by parallel electric field and diffusion in location momentum and pitch angle It can become a theoretical foundation for developing future numerical models of particle transport including particle acceleration in the magnetosphere In this paper we will concentrate on the discussion of particle acceleration in relation to the dynamics of the magnetospheric plasma Using a model map of magnetospheric convection pattern we have found that the compression of magnetospheric plasma can play important roles in particle acceleration and trapping The compressional particle acceleration is similar to the first-order Fermi acceleration that occurs at shock waves in other space plasma settings The strongest compressional acceleration occurs in near-Earth magnetotail This mechanism may possibly be the cause of the in-situ acceleration of relativistic electrons in the outer radiation belt particularly during magnetic storm periods In addition we will discuss the condition and possibility of stochastic acceleration of particles during

  19. How Deep Convective Overshooting Over Land Can Penetrate The Stratosphere?

    NASA Astrophysics Data System (ADS)

    Pommereau, J.; Held, G.

    2006-12-01

    The amount of water vapour and ozone depleting substances in the stratosphere depends on how tropospheric air is transported across the Tropical Tropopause Layer (TTL) into the stratosphere. Following Newell and Gould-Stewart (1982) it is generally assumed that Troposphere-Stratosphere exchange occurs where the tropopause is the coldest, the "Stratospheric Fountain" over the Maritime continent. However, if convective transport is observed to reach the TTL around 14km over oceans, there is no indication that it could cross the Tropopause around 17.5km at 360-370K. A further mechanism is required attributed to slow radiative heating. However and although thought to be infrequent, it has been shown that overshoots over land could penetrate deeper the stratosphere. Indeed and in contrast to oceanic convection, land systems are displaying a strong diurnal cycle resulting in fast afternoon uplifts. Here we investigate the impact of convection on TTL temperature over Brazil during the summer from 4 daily radiosondes in February 2004 during the HIBISCUS campaign. In the presence of deep convection, the TTL is found to be cooler above the tropopause between 16 and 19 km (maximum 8K at 17 km). About half of this is shown to be due to a systematic diurnal variation displaying an average cooling of 3-4 K at 17-18 km in the afternoon between 11:00 and 17:00 LST, during the development phase of convection. Since this cooling occurs 1-2 km above the tropopause, during daytime and within a time scale of 6h, it cannot be attributed to radiation, adiabatic lofting of the tropopause or large-scale waves, suggesting insertion of cold air parcels by overshooting followed by mixing with the warmer environment. During most intense convective days, the overshoot is shown to penetrate the stratosphere up to 440K potential temperature levels.

  20. UW Summer STEM Undergraduate

    E-print Network

    Kaminsky, Werner

    UW Summer STEM Undergraduate Research Poster SessionWednesday, August 21st, 2013 9:00 am--12 noon to conduct research in STEM fields. For more information, contact the Undergraduate Research Program at: urp

  1. Rebuilding of the Earth's Outer Electron Belts During the 9 October 2012 and 17 March 2013 Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Kress, B. T.; Hudson, M. K.; Paral, J.; McGregor, S. L.

    2014-12-01

    The build up of ~1 MeV electrons near geosynchronous orbit observed during the recovery period of the 9 October 2012 geomagnetic storm is well modeled by computing test-particle trajectories in MHD magnetospheric model fields. Comparison between data and model results shows that the recovery of ~1 MeV radiation belt electrons near geosynchronous is mainly due to global convection and dipolarization associated injections from the plasma sheet [Kress et al., GRL, 2014]. Energetic particle measurements made with the Van Allen Probes spacecraft during this geomagnetic storm suggest that transport of electrons with energies up to ~2 MeV is driven by convection well inside of geosynchronous orbit, in a region where radiation belt transport is usually treated as diffusive. The general build up of outer belt electrons during the 17 March 2013 geomagnetic storm is also well modeled with test-particle trajectories in global MHD magnetospheric model fields. Rapid transport of plasma sheet electrons may provide a seed population for local acceleration mechanisms, resulting in the observed enhancements in 2-6 MeV outer radiation belt flux.

  2. Towards evaluating the intensity of convective systems by using GPS radio occultation profiles

    NASA Astrophysics Data System (ADS)

    Biondi, Riccardo; Steiner, Andrea K.; Kirchengast, Gottfried

    2015-04-01

    Deep convective systems, also more casually often just called storms, are destructive weather phenomena causing every year many deaths, injuries and damages and accounting for major economic losses in several countries. The number and intensity of such phenomena increased over the last decades in some areas of the globe, including Europe. Damages are mostly caused by strong winds and heavy rain and these parameters are strongly connected to the structure of the storm. Convection over land is usually stronger and deeper than over the ocean and some convective systems, known as supercells, also develop tornadoes through processes which are still mostly unclear. The intensity forecast and monitoring of convective systems is one of the major challenges for meteorology because in-situ measurements during extreme events are too sparse or not reliable and most ongoing satellite missions do not provide suitable time/space coverage. With this study we propose a new method for detecting the convection intensity in terms of rain rate and surface wind speed by using meteorological surface measurements in combination with atmospheric profiles from Global Positioning System (GPS) radio occultation observations, which are available in essentially all weather conditions and with global coverage. The analysis of models indicated a relationship between the cloud top altitude and the intensity of a storm. We thus use GPS radio occultation bending angle profiles for detecting the storm's cloud top altitude and we correlate this value to the rain rate and wind speed measured by meteorological station networks in two different regions, the WegenerNet climate station network (South-Eastern Styria, Austria) and the Atmospheric Radiation Measurement site (ARM, Southern Great Plains, USA), respectively. The results show a good correlation between the cloud top altitude and the maximum rain rate in the monitored areas, while this is not found for maximum wind speed. We conclude from this initial study that for land convective systems the cloud top altitude is strongly connected to the rain intensity and that GPS radio occultation observations show encouraging potential to improve the intensity nowcasting and detection of such kind of severe weather phenomena.

  3. 'RCHX-1-STORM' first Slovenian meteorological rocket program

    NASA Astrophysics Data System (ADS)

    Kerstein, Aleksander; Matko, Drago; Trauner, Amalija; Britovšek, Zvone

    2004-08-01

    Astronautic and Rocket Society Celje (ARSC) formed a special working team for research and development of a small meteorological hail suppression rocket in the 70th. The hail suppression system was established in former Yugoslavia in the late 60th as an attempt to protect important agricultural regions from one of the summer's most vicious storm. In this time Slovenia was a part of Yugoslavia as one of the federal republic with relative high developed agricultural region production. The Rocket program 'RCHX-STORM' was a second attempt, for Slovenia indigenously developed in the production of meteorological hail suppression rocket. ARSC has designed a family of small sounding rocket that were based on highly promising hybrid propellant propulsion. Hybrid propulsion was selected for this family because it was offering low cost, save production and operation and simple logistics. Conventional sounding rockets use solid propellant motor for their propulsion. The introduction of hybrid motors has enabled a considerable decrease in overall cost. The transportation handling and storage procedures were greatly simplified due to the fact that a hybrid motor was not considered as explosive matter. A hybrid motor may also be designed to stand a severe environment without resorting to conditioning arrangements. The program started in the late 70th when the team ARSC was integrated in the Research and Development Institute in Celje (RDIC). The development program aimed to produce three types of meteorological rockets with diameters 76, 120 and 160 mm. Development of the RCHX-76 engine and rocket vehicle including flight certification has been undertaken by a joint team comprising of the ARCS, RDIC and the company Cestno podjetje Celje (CPC), Road building company Celje. Many new techniques and methods were used in this program such as computer simulation of external and internal ballistics, composite materials for rocket construction, intensive static testing of models and flight configuration with long flight-testing program. The main features of this project were discussed in this paper, summarizing the history of the development of the RCHX-STORM rockets family.

  4. Rotating convection in elliptical geometries

    NASA Astrophysics Data System (ADS)

    Evonuk, M.

    2014-12-01

    Tidal interactions between hot jupiter planets and their host stars are likely to result in non-spherical geometries. These elliptical instabilities may have interesting effects on interior fluid convective patterns, which in turn influence the nature of the magnetic dynamo within these planets. Simulations of thermal convection in the 2D rotating equatorial plane are conducted to determine to first order the effect of ellipticity on convection for varying density contrasts with differing convective vigor and rotation rate. This survey is conducted in two dimensions in order to simulate a broad range of ellipticities and to maximize the parameter space explored.

  5. Convective Distribution of Tropospheric Ozone and Tracers in the Central American ITCZ Region: Evidence from Observations During TC4

    NASA Technical Reports Server (NTRS)

    Avery, Melody; Twohy, Cynthia; MCabe, David; Joiner, Joanna; Severance, Kurt; Atlas, Eliot; Blake, Donald; Bui, T. P.; Crounse, John; Dibb, Jack; Diskin, Glenn; Lawson, Paul; McGill, Matthew; Rogers, David; Sachse, Glen; Scheuer, Eric; Thompson, Anne M.; Trepte, Charles; Wennberg, Paul; Ziemke, Jerald

    2010-01-01

    During the Tropical Composition, Clouds and Climate Coupling (TC4) experiment that occurred in July and August of 2007, extensive sampling of active convection in the ITCZ region near Central America was performed from multiple aircraft and satellite sensors. As part of a sampling strategy designed to study cloud processes, the NASA ER-2, WB-57 and DC-8 flew in stacked "racetrack patterns" in convective cells. On July 24, 2007, the ER-2 and DC-8 probed an actively developing storm and the DC-8 was hit by lightning. Case studies of this flight, and of convective outflow on August 5, 2007 reveal a significant anti-correlation between ozone and condensed cloud water content. With little variability in the boundary layer and a vertical gradient, low ozone in the upper troposphere indicates convective transport. Because of the large spatial and temporal variability in surface CO and other pollutants in this region, low ozone is a better convective indicator. Lower tropospheric tracers methyl hydrogen peroxide, total organic bromine and calcium substantiate the ozone results. OMI measurements of mean upper tropospheric ozone near convection show lower ozone in convective outflow. A mass balance estimation of the amount of convective turnover below the tropical tropopause transition layer (TTL) is 50%, with an altitude of maximum convective outflow located between 10 and 11 km, 4 km below the cirrus anvil tops. It appears that convective lofting in this region of the ITCZ is either a two-stage or a rapid mixing process, because undiluted boundary layer air is never sampled in the convective outflow.

  6. Deep convective clouds at the tropopause

    NASA Astrophysics Data System (ADS)

    Aumann, H. H.; Desouza-Machado, S. G.

    2010-07-01

    Data from the Advanced Infrared Sounder (AIRS) on the EOS Aqua spacecraft identify thousands of cloud tops colder than 225 K, loosely referred to as Deep Convective Clouds (DCC). Many of these cloud tops have "inverted" spectra, i.e. areas of strong water vapor, CO2 and ozone opacity, normally seen in absorption, are now seen in emission. We refer to these inverted spectra as DCCi. They are found in about 0.4% of all spectra from the tropical oceans excluding the Western Tropical Pacific (WTP), 1.1% in the WTP. The cold clouds are the anvils capping thunderstorms and consist of optically thick cirrus ice clouds. The precipitation rate associated with DCCi suggests that imbedded in these clouds, protruding above them, and not spatially resolved by the AIRS 15 km FOV, are even colder bubbles, where strong convection pushes clouds to within 5 hPa of the pressure level of the tropopause cold point. Associated with DCCi is a local upward displacement of the tropopause, a cold "bulge", which can be seen directly in the brightness temperatures of AIRS and AMSU channels with weighting function peaking between 40 and 2 hPa, without the need for a formal temperature retrieval. The bulge is not resolved by the analysis in numerical weather prediction models. The locally cold cloud tops relative to the analysis give the appearance (in the sense of an "illusion") of clouds overshooting the tropopause and penetrating into the stratosphere. Based on a simple model of optically thick cirrus clouds, the spectral inversions seen in the AIRS data do not require these clouds to penetrate into the stratosphere. However, the contents of the cold bulge may be left in the lower stratosphere as soon as the strong convection subsides. The heavy precipitation and the distortion of the temperature structure near the tropopause indicate that DCCi are associated with intense storms. Significant long-term trends in the statistical properties of DCCi could be interesting indicators of climate change.

  7. The Impacts of Aerosol Indirect Forcing on Dynamical Aspects of Deep Convection

    NASA Astrophysics Data System (ADS)

    van den Heever, S. C.

    2011-12-01

    Convective storms appear to be invigorated in polluted conditions through the influence of aerosol indirect forcing on diabatic heating and other processes. However, the mechanisms by which such invigoration occurs are still not well understood and are often complicated by feedbacks to the microphysics and storm dynamics. For example, varying the raindrop size distribution from a population of many small raindrops to a population of a few large raindrops through aerosol indirect effects influences evaporation rates, and hence the area and intensity of the cold pool. However, the intensity of the cold pool can in turn influence the strength of convective updrafts and hence the characteristics of the rainfall that is produced. It has also been suggested that the suppression of the warm rain process under enhanced cloud condensation nuclei (CCN) concentrations generates more cloud water that can be lofted above the freezing level which, upon freezing, releases greater amounts of latent heat than would have been released in cleaner conditions. The enhanced latent heat release increases buoyancy and hence the updraft strength. However, the increased cloud and ice water mass generated in polluted conditions will also have a negative impact on the updraft strength through precipitation loading. The focus of this talk will be on the impacts of aerosol indirect forcing on two particular dynamical features of convective storms: (1) the strength of the updraft, and (2) the cold pool dynamics. The processes responsible for aerosol impacts on these dynamical features of tropical and midlatitude storms, as well as their relative importance will be analyzed using the output of numerous cloud-resolving model experiments.

  8. Transport across the tropical tropopause layer and convection

    NASA Astrophysics Data System (ADS)

    Tissier, Ann-Sophie; Legras, Bernard; Tzella, Alexandra

    2015-04-01

    We investigate how air parcels detrained from convective sources enter the TTL. The approach is based on the comparison of unidimensional trajectories and Lagrangian backward and forward trajectories, using TRACZILLA and ERA-Interim. Backward trajectories are launched at 380K and run until they hit a deep convective cloud. Forward trajectories are launched at the top of high convective clouds identified by brightness temperature from CLAUS dataset. 1D trajectories are computed using Gardiner's method. Results show that the warm pool region during winter and the Bay of Bengal / Sea of China during summer are the prevalent sources as already identified in many previous studies and we quantify the respective role of the various regions. We show that the 1D model explains qualitatively and often quantitatively the 3d results. We also show that in spite of generating very high convection, Africa is quite ineffective as providing air that remains in the TTL while on the opposite the Tibetan Plateau is the most effective region in this respect although its total contribution is minor. Finally, we compare ERA-Interim, JRA-55 and MERRA reanalysis and find large similarities between the two formers.

  9. Potential For Early Warning of Dust Storms

    NASA Astrophysics Data System (ADS)

    Kafatos, M.; El-Askary, H.; Kallos, G.

    Dust storms can be devastating events in many continents, extremely adverse influences over large parts of the Earth. They are a cause of health, environmental and even economic problem. As such, the potential of early warning before a dust storm is fully developed becomes of paramount importance. Remote sensing using a variety of sensors and techniques can be utilized to provide information as dust storm is developing. Direct broadcasting data collected by, e.g., HRPT or MODIS antennas provide L1B information at all stages. Indices that characterize specific dust storms can be developed using the multi-angle view provided by MISR. Other methods will be discussed utilizing OLR, as well as combining RS information with mesoscale, high-resolution model (e.g. SKIRON). The SKIRON/Eta modeling system is limited area weather and dust cycle forecasting system able to accurately simulate weather conditions and the desert dust uptake-transport-deposition cycle. Modeling can provide insights of how dust storms occur and how dust transports.

  10. Asian summer monsoon onset barrier and its formation mechanism

    NASA Astrophysics Data System (ADS)

    Liu, Boqi; Liu, Yimin; Wu, Guoxiong; Yan, Jinghui; He, Jinhai; Ren, Suling

    2014-08-01

    The onset process of Asian summer monsoon (ASM) is investigated based on diagnostic analysis of observations of precipitation and synoptic circulation. Results show that after the ASM commences over the eastern Bay of Bengal (BOB) around early May, the onset can propagate eastwards towards the South China Sea and western Pacific but is blocked on its westward propagation along the eastern coast of India. This blocking, termed the "monsoon onset barrier (MOB)", presents a Gill-type circulation response to the latent heating released by BOB monsoon convection. This convective condensation heating generates summertime (wintertime) vertical easterly (westerly) shear to its east (west) and facilitates air ascent (descent). The convection then propagates eastward but gets trapped on its westward path. To the east of the central BOB, the surface air temperature (SAT) cools faster than the underlying sea surface temperature (SST) due to monsoon onset. Thus more sensible heat flux supports the onset convection to propagate eastward. To the west of the central BOB, however, the land surface sensible heating over the Indian Peninsula is strengthened by the enhanced anticyclone circulation and air descent induced by the BOB monsoon heating. The strengthened upstream warm horizontal advection then produces a warm SAT center over the MOB region, which together with the in situ cooled SST reduces the surface sensible heating and atmospheric available potential energy to prevent the occurrence of free convection. Therefore, it is the change in both large-scale circulation and air-sea interaction due to BOB summer monsoon onset that contributes to the MOB formation.

  11. Generated using version 3.2 of the official AMS LATEX template Summer season squall line simulations: Sensitivity of gravity1

    E-print Network

    Alexander, M. Joan

    simulations: Sensitivity of gravity1 waves to physics parameterization and implications for their2.stephan@colorado.edu 1 #12;ABSTRACT6 Gravity waves have important effects on the middle atmosphere circulation, and those of gravity wave momentum flux above the storm irrespective of the19 convective details that coarse resolution

  12. Evaluation of the Importance of Wet Scavenging for the may 29, 2012 DC3 Severe Storm Case Using Results from Wrf-Chem Simulations

    NASA Astrophysics Data System (ADS)

    Bela, M. M.; Barth, M. C.; Toon, O.; Fried, A.; Morrison, H.; Pickering, K. E.; Cummings, K.; Li, Y.; Allen, D. J.; Manning, K.

    2013-12-01

    Deep convective thunderstorms affect the vertical distribution of chemical species through vertical transport, lightning-production of NOx, wet scavenging of soluble species as well as aqueous and ice chemistry. This work focuses on the May 29 Oklahoma thunderstorm from the DC3 (Deep Convective Clouds and Chemistry) field campaign. WRF-Chem simulations at cloud parameterizing scales (dx=15km) and cloud resolving scales (dx=3 and 1km) are conducted to investigate wet scavenging of soluble trace gases. Two different wet scavenging schemes are coupled to the Morrison microphysics scheme and MOZART chemistry. The first, based on Neu and Prather (ACP, 2012), tracks dissolved species in cloud droplets and precipitation and releases species to the gas phase from evaporating precipitation. However, it does not distinguish between precipitating liquid and ice, and species are completely retained upon hydrometeor freezing. The second, described in Barth et al. (JGR, 2001), tracks solute in individual liquid and frozen hydrometeors, and a new capability to specify the fraction of each species that is retained in ice upon hydrometeor freezing is added. The simulated meteorology, evaluated with the NEXRAD radar reflectivity, is shown to represent the structure and evolution of the storm, although the simulated storm triggers about an hour early, has a larger area of high reflectivity and extends further north than observed in NEXRAD. Vertical distributions of trace gases with varying solubilities within the storm and immediately surrounding the storm are compared with observations from the GV and DC-8 aircraft in storm inflow and outflow regions. Using the Neu and Prather scheme or using the Barth scheme with zero or complete ice retention, observed mean vertical profiles of some soluble species in outflow are better represented in the model with scavenging, while others are overly scavenged. Finally, sensitivity studies are conducted to determine ice retention factors for each species and included in the Barth scavenging scheme to improve the model representation of convective cloud transport and processing of chemical species.

  13. Dynamics of high-latitude patches and associated small-scale irregularities during the October and November 2003 storms

    NASA Astrophysics Data System (ADS)

    de Franceschi, Giorgiana; Alfonsi, Lucilla; Romano, Vincenzo; Aquino, Marcio; Dodson, Alan; Mitchell, Cathryn N.; Spencer, Paul; Wernik, Andrzej W.

    2008-04-01

    Observations from a network of specially equipped GPS scintillation receivers in Northern Europe are used to investigate the dynamics of ionospheric plasma during the storm events of 30 October and 20 November 2003. The total electron content (TEC) and scintillation data, combined with ionospheric tomography produced by the multi-instrument data analysis system (MIDAS), reveal strong enhancements and steep gradients in TEC during nighttime under a prevailing negative Bz component of the interplanetary magnetic field (IMF). Amplitude and phase scintillation maxima are often co-located with the TEC gradients at the edge of plasma patches, revealing the presence of small-scale irregularities and suggesting association with a tongue of ionization (TOI) convecting in an anti-sunward direction from the American sector across the polar cap. Similarities and differences between the ionospheric response to the two storms are investigated. The 30 October event reveals a quite complex scenario showing two phases of plasma dynamics: the former reflects the expected convection pattern for IMF Bz southward and the latter possibly indicates a sort of TEC plasma stagnation signature of the more complex convection patterns during several positive/negative excursions of IMF Bz.

  14. Evolution of Upper Tropospheric Composition Perturbed by a Mesoscale Convective System during the Deep Convective Clouds and Chemistry (DC3) Campaign

    NASA Astrophysics Data System (ADS)

    Cantrell, C. A.; Barth, M. C.; Brune, W. H.; Rutledge, S. A.; Crawford, J. H.; Olson, J. R.; Flocke, F. M.

    2013-12-01

    The role of deep convection in altering the chemical composition of the upper troposphere (UT) is well known, having been observed in many airborne campaigns, including dedicated studies that were part of the Deep Convective Clouds and Chemistry (DC3) experiment in May and June, 2012. The primary focus of DC3 was to characterize the details of transport from the boundary layer to the UT by isolated convective cells, and further to examine the evolution of air masses perturbed by the convection as chemical processing takes place the day after convective transport. These objectives were addressed by observations staged aboard the NSF/NCAR GV and NASA DC-8 aircraft platforms, which were deployed to study storms in Colorado, Oklahoma/West Texas, and northern Alabama, and to study aged outflow downwind of the storms. Because of the importance of Mesoscale Convective Systems (MCSs) in convective transport, their impact was assessed on two occasions as observations of opportunity during flights focused on other goals, and during one dedicated mission. The latter focused on a decaying nocturnal MCS that formed over the north central Great Plains and moved to the east over Illinois, Indiana, and Missouri during the day on June 21, 2012. The aircraft platforms were staged such that the DC-8 observed the aging from early morning to midday, and the GV observed from midday to early evening. The two aircraft overlapped on part of a flight leg to connect the measurements on the two platforms. This provided a 10.5 hour record of the atmospheric processing of the concentrations of a variety of gas-phase species as well as the composition and size distributions of aerosols in the outflow. By making use of air mass trajectories, the observations are placed on a photochemical age scale. This allows calculations of ozone production, production and growth of aerosols, net production of nitric acid, and budgets of HOx and its reservoirs in the MCS outflow. This provides quantitative information on the role of convection from MCSs in UT chemical composition and evolution. Flight tracks of DC-8 (magenta) and GV (yellow and red) during the MCS study on June 21, 2012. Visible and infrared satellite images near the end of the day are also shown. The numbers show the time (UTC) along the aircraft flight tracks.

  15. The Semiannual Variation of Great Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Svalgaard, L.; Cliver, E. W.; Ling, A. G.

    2001-12-01

    The occurrence frequency of the largest geomagnetic storms as measured by the aa index from 1868-present exhibits a well-defined semiannual modulation with 2.4 times as many great storms occurring during equinoctial months than at the solstices. We show that most, but not all, of this variation can be attributed to an equinoctial hypothesis whereby energy transfer from the solar wind to the magnetosphere is modulated by psi, the angle between the solar wind flow direction and Earth's dipole axis. After normalizing aa for the seasonal/daily variation of psi, the imbalance in great storm counts between equinoctial and solstitial months is reduced to a factor of 1.4.

  16. Science Sampler: Studying storms to understand weather

    NSDL National Science Digital Library

    Shane Cavanaugh

    2007-03-01

    Who isn't awed by the power, beauty, and destructive capabilities of a hurricane, tornado, or snowstorm? Storms are one of those topics that nearly all students are interested in, and by capitalizing on this interest and focusing on the big idea behind storms, educators can teach weather in a meaningful and motivating way. The five-week unit described here deliberately and actively highlights interesting or surprising aspects of weather, namely storms. Rather than a typical inquiry unit, this curriculum engages students in social construction of their understandings of weather in small- and large-group discussions, as well as a significant amount of exploration of weather concepts using online simulations, animations, and other resources.

  17. Evaluation of thermally driven flows and orographic convection at cloud-resolving resolutions

    NASA Astrophysics Data System (ADS)

    Schmidli, J.; Langhans, W.; Fuhrer, O.; Bieri, S.; Schar, C.

    2013-12-01

    The purpose of this contribution is to evaluate the representation of thermally driven flows and moist convection over the European Alps at cloud-resolving resolutions (CRM; 1.1 and 2.2 km). The two simulations and further sensitivity experiments are validated against a large set of observations for an 18-day fair-weather summer period. The episode considered is characterized by pronounced plain-valley pressure gradients, strong daytime upvalley flows, and weak nighttime down-valley flows. In addition, convective precipitation is recorded during the late afternoon and is preceded by a phase of shallow convection. The observed transition from shallow to deep convection occurs within a 3-h period. The results indicate generally good agreement between both CRMs and the observed diurnal evolution in terms of near-surface winds, cloud formation, and precipitation. The differences between the 1.1 and 2.2 km resolution runs are surprisingly small. In contrast, a convection-parameterizing simulation with 6.6 km resolution (CPM) produces too-early peaks of cloud cover and precipitation that are due to a too-early activation of deep convection. Detailed sensitivity experiments show that the convection scheme, rather than the under-resolved small-scale topography, is responsible for the poor performance of the CPM.

  18. Total Lightning and Radar Storm Characteristics Associated with Severe Storms in Central Florida

    NASA Technical Reports Server (NTRS)

    Goodman, Steven J.; Raghavan, Ravi; Ramachandran, Rahul; Buechler, Dennis; Hodanish, Stephen; Sharp, David; Williams, Earle; Boldi, Bob; Matlin, Anne; Weber, Mark

    1998-01-01

    A number of prior studies have examined the association of lightning activity with the occurrence of severe weather and tornadoes, in particular. High flash rates are often observed in tornadic storms (Taylor, 1973; Johnson, 1980; Goodman and Knupp, 1993) but not always. Taylor found that 23% of nontornadic storms and 1% of non-severe storms had sferics rates comparable to the tornadic storms. MacGorman (1993) found that storms with mesocyclones produced more frequent intracloud (IC) lightning than cloud-to-ground (CG) lightning. MacGorman (1993) and others suggest that the lightning activity accompanying tomadic storms will be dominated by intracloud lightning-with an increase in intracloud and total flash rates as the updraft increases in depth, size, and velocity. In a recent study, Perez et al. (1998) found that CG flash rates alone are too variable to be a useful predictor of (F4, F5) tornado formation. Studies of non-tomadic storms have also shown that total lightning flash rates track the updraft, with rates increasing as the updraft intensities and decreasing rapidly with cessation of vertical growth or downburst onset (Goodman et al., 1988; Williams et al., 1989). Such relationships result from the development of mixed phase precipitation and increased hydrometer collisions that lead to the efficient separation of charge. Correlations between updraft strength and other variables such as cloud-top height, cloud water mass, and hail size have also been observed.

  19. Stagnant lid convection on Venus

    Microsoft Academic Search

    V. S. Solomatov; L.-N. Moresi

    1996-01-01

    The effect of strongly temperature-dependent viscosity on convection in the interior of Venus is studied systematically with the help of finite element numerical models. For viscosity contrasts satisfying experimental constraints on the rheology of rocks, Venus is likely to be in the regime of stagnant lid convection. This regime is characterized by the formation of a slowly creeping, very viscous

  20. Slantwise Convection: An Operational Approach

    NSDL National Science Digital Library

    2014-09-14

    This Webcast is a recreation of a presentation on slantwise convection given by Kent Johnson in February, 2002 in Boulder, Colorado. It focuses on assessing the release of conditional symmetric instability as slantwise convection. It provides an overview of the characteristics and theory of CSI, assessment of CSI and slantwise induced precipitation in complex terrain, and operational challenges to assessing CSI.