These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

East Asian Summer monsoon precipitation systems: rainfall characteristics, storm morphologies and convective properties.  

E-print Network

??This study attempts to characterize the particular convection type, namely storm morphologies, convective properties, and microphysics, of different weather regimes within the East Asian Summer… (more)

Xu, Weixin

2011-01-01

2

Radar Observations Of Lake Breeze Induced Summer Convective Storms  

NASA Astrophysics Data System (ADS)

Observations of convective precipitation made with a portable X-band radar are com- pared to images retrieved from the Exeter C-band operational radar situated in south- ern Ontario during Elbow 2001: The Effect of Lake Breezes On Weather. Attempts were made to locate and identify convective precursors of summer severe weather due to lake breeze boundary interactions with the X-band radar. As a diagnostic and prog- nostic observation and analysis tool, the X-band was able to make contributions to the research from the perspective of scanning flexibility. In comparison, the more sensitive C-band operational radar performed far better as a means of detecting boundary in- teractions well in advance of severe weather, making it a more effective research tool. The boundary interactions on June 19, July 19, and July 23 of 2001, are presented as case studies to illustrate the performance strengths of each radar.

Donaldson, N.; Firanski, B.; Hudak, D.; Sills, D.; Taylor, P.

3

East Asian summer monsoon precipitation systems: Rainfall characteristics, storm morphologies and convective properties  

NASA Astrophysics Data System (ADS)

This study attempts to characterize the particular convection type, namely storm morphologies, convective properties, and microphysics, of different weather regimes within the East Asian Summer Monsoon (EASM). Defined rain bands and associated rainfall characteristics are examined in terms of population, location, variability, and rainfall frequency. Though the Mei-Yu rain bands produce a relatively large rain belt over South China and Taiwan during mid-May to mid-June, and over the Yangtze River region during mid-June to mid-July, rainfall maxima and heavy precipitation are most frequent over specific locations. Generally, the frequency of storms with high echo tops, significant convection, and evident ice scattering signature is greatest in post-Meiyu and break periods, less so during the active Mei-Yu, and least frequent before the monsoon onset. However, preseason, as well as break periods, has a larger fraction of intense convection that behaves more like the classic continental tropical convection with major ice-based rainfall processes. Specifically, preseason and break periods have a larger fraction of rainfall contributed from storms with a 40-dBZ convective core extending above 7-8 km. By comparison, active Mei-Yu convection more closely resembles classic tropical maritime convection with relatively more importance of "warm-rain" collision and coalescence processes with weaker convection but heavy precipitation. Monsoon precipitation over the Yangtze River region, though having similar size and cloud top, differs from its counterpart in South China on convective properties, vertical structures, and rainfall contribution by storm types. Based on Tropical Rainfall Measuring Mission (TRMM) climatology, the EASM is comparable to other monsoon regimes by having convective properties intermediate between the intense convective systems over continents, and the weaker convective systems found in the classic maritime precipitation regimes. Analysis based on Terrain-influenced Monsoon Rainfall Experiment (TiMREX) observations indicates that most of the heavy rainfall is associated with Mei-Yu rain bands, strongly influenced by upstream low-level jets, unstable upstream conditions, but a more nearly moist neutral storm environment. A particular long-duration heavy precipitation event is analyzed in detail, and features continuous development of "back-building" new convection under the influence of an extensive precipitation-created cold pool and substantial orography downstream.

Xu, Weixin

4

Towards an offline parameterization of convective dust storms  

NASA Astrophysics Data System (ADS)

Around half of dust emissions worldwide originate from the Sahel and Sahara regions, of which a major but uncertain fraction are caused by convectively-generated dust storms (haboobs). In these storms, evaporation-driven downdrafts form cold pools that quickly propagate and create near-surface wind gusts. Current global models do not capture such storms, because their convection schemes do not allow effective formation of such cold pools. We suggest a parameterization of near-surface wind gusts and dust emissions generated by cold pools, based on the downdraft mass flux from the convection scheme. It assumes the horizontal dispersion of all downdrafts into cold pools and the unknown geometry of the cold pools results in one free parameter. The parameterization is applied to Unified Model (Cascade) runs for the 2006 Summer in West Africa. The free parameter is tuned for 40-km and 12-km runs with convection scheme, using 4-km convection-permitting runs as a reference (4-km runs have been evaluated using 1.5-km runs in previous studies). The parameterization successfully increases the near-surface wind beyond the threshold for dust emission and compensates for the lack of convectively-generated dust storms when the convection scheme is activated. The long-standing problem of too early activation of the convection scheme in the Sahel and Sahara regions remains an issue in the parameterization of the diurnal cycle of dust emissions. This parameterization is developed in the framework of the ERC Desert Storms project.

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

2014-05-01

5

Interactions Between Convective Storms and Their Environment  

NASA Technical Reports Server (NTRS)

The ways in which intense convective storms interact with their environment are considered for a number of specific severe storm situations. A physical model of subcloud wind fields and vertical wind profiles was developed to explain the often observed intensification of convective storms that move along or across thermal boundaries. A number of special, unusually dense, data sets were used to substantiate features of the model. GOES imagery was used in conjunction with objectively analyzed surface wind data to develop a nowcast technique that might be used to identify specific storm cells likely to become tornadic. It was shown that circulations associated with organized meso-alpha and meso-beta scale storm complexes may, on occasion, strongly modify tropospheric thermodynamic patterns and flow fields.

Maddox, R. A.; Hoxit, L. R.; Chappell, C. F.

1979-01-01

6

Principles of Convection III: Shear and Convective Storms  

NSDL National Science Digital Library

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.

Comet

2003-11-18

7

Principles of Convection III: Shear and Convective Storms  

NSDL National Science Digital Library

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.

Spangler, Tim

2003-10-01

8

A stochastic method for convective storm identification, tracking and nowcasting  

Microsoft Academic Search

The convective storm identification, tracking and nowcasting method is one of the important nowcasting methodologies against severe convective weather. In severe convective cases, such as storm shape or rapid velocity changes, existing methods are apt to provide unsatisfied storm identification, tracking and nowcasting results. To overcome these difficulties, this paper proposes a novel approach to identify, track and short-term forecast

Lei Han; Shengxue Fu; Guang Yang; Hongqing Wang; Yongguang Zheng; Yingjing Lin

2008-01-01

9

Urban Aerosol Impacts on Downwind Convective Storms  

Microsoft Academic Search

The impacts of urban-enhanced aerosol concentrations on convective storm development and precipita- tion over and downwind of St. Louis, Missouri, are investigated. This is achieved through the use of a cloud-resolving mesoscale model, in which sophisticated land use processes and aerosol microphysics are both incorporated. The results indicate that urban-forced convergence downwind of the city, rather than the presence of

Susan C. van den Heever; William R. Cotton

2007-01-01

10

Moist convective storms in the atmosphere of Saturn  

Microsoft Academic Search

Moist convective storms might be a key aspect in the global energy budget of the atmospheres of the Giant Planets. In spite of its dull appearance, Saturn is known to develop the largest scale convective storms in the Solar System, the Great White Spots, the last of them arising in 1990 triggered a planetary scale disturbance that encircled the whole

R. Hueso; A. Sánchez-Lavega

2003-01-01

11

A MODEL FOR LARGE SCALE CONVECTIVE STORMS IN JUPITER  

E-print Network

1 A MODEL FOR LARGE SCALE CONVECTIVE STORMS IN JUPITER Ricardo Hueso(1) , Agustín Sánchez-Lavega(2 storms are a common phenomenon in Jupiter's atmosphere. They are apparent in ground-based and spacecraft that ~10^16 W are released by such a storm over its life cycle of 12 days and that the direct formation

Guillot, Tristan

12

Seamless Probabilistic Forecasting of Convective Storms  

NASA Astrophysics Data System (ADS)

Different methods are used to provide forecasts of precipitation with different lead times, and a major challenge is to provide seamless forecasts across the range of times of interest to a decision maker. Firstly, the detailed precipitation map obtained from Radar can be extrapolated into the future by advecting the precipitation pattern ("Nowcasting"), although the forecast quality degrades rapidly in the first hours because the dynamics of the storm are not accurately represented. At longer lead times numerical weather prediction ("NWP") is superior since it includes dynamical effects, but cannot match the skill of nowcasting in the first few hours due to the difficulty of assimilating precipitation observations. A seamless combination of these methods requires knowledge of their errors, and is difficult because the predictability depends strongly on the meteorological situation. However it is now becoming possible with the availability of probabilistic predictions from ensembles of high resolution forecasts. These concepts will be illustrated using ensemble forecasts of convective events with the 2.8 km resolution COSMO-DE model nested within different forecasts from the COSMO-LEPS ensemble. Probabilistic nowcasts are produced using the Cb-TRAM system that tracks convective a convective cloud field using an optical flow method. The images are then extrapolated forward in time and probabilistic forecasts are generated using the local Lagrangian method. Examples will be shown to illustrate how the forecast skill of the two methods is influenced by the inherent predictability of the meteorological situation, in particular the degree of control of convective by the synoptic flow.

Craig, G. C.

2009-04-01

13

Aerosol Indirect Forcing of Deep Convective Storm Dynamics  

NASA Astrophysics Data System (ADS)

Aerosol indirect effects can influence a number of the dynamical aspects of deep convective storms through their impacts on the thermodynamical and radiative processes of such storms. Variations in the drop and ice crystal size distributions influence evaporation and melting rates and hence the intensity and dynamics of the storm-produced cold pool. Such aerosol-induced changes to the cold pool characteristics may influence the manner in which storm outflow boundaries interact, the frequency, organization and intensity of subsequent convection, and the longevity of the parent convection, especially in regions in which multiple convective storms develop simultaneously. Variations in the melting rate of ice species such as graupel and hail can also influence other dynamical features of organized deep convection such as rear inflow jet, which in turn has implications for squall line intensity and bowing. Variations in aerosol number concentrations can also impact the updraft strength through changes to latent heat release and condensate loading. Changes in the updraft strength are associated with changes in the convective mass flux, anvil thickness, and detrainment and subsidence rates. Such deviations in the anvil characteristics produce changes in the anvil radiative forcing with subsequent feedbacks to static stability and updraft modulation. Altering the detrainment and subsidence rates of deep convective systems may also influence the development of neighboring convective cells. It is thus apparent that enhanced aerosol concentrations may have significant effects not only on the storm of interest, but also on neighboring convective storms and secondary convective development through their influence on anvil and cold pool dynamics. The aerosol-induced cold pool and anvil feedbacks to storm intensity and longevity may vary significantly both in magnitude and sign, thus potentially offsetting one another. The results of several idealized cloud-resolving simulations designed to assess the impacts of aerosol-induced changes in cold pool and anvil forcing on storm intensity and longevity will be presented.

van den Heever, S. C.

2012-04-01

14

Remote sensing of severe convective storms  

NASA Technical Reports Server (NTRS)

The Tibet Plateau significantly affects the initiation and development of heavy rainfall and severe storms in China, just as the Rocky Mountains influence local severe storms in the United States. The study shows that the heavy rainfall in the Plateau area is usually preceded by a high growth rate of the convective clouds, followed by a rapid collapse of the cloud top. The study also shows that the tops of the convective clouds associated with heavy rainfall over the Plateau usually lie between the altitude of the two tropopauses which exist over the Plateau. There is good agreement between the collapsing of the cloud as observed from the satellite imagery, and the beginning of the rainfall observed by the ground stations and also between the dissipation of the cloud observed from the satellite infrared imagery, and the ending of the rainfall, observed by the ground stations. Comparison of the volumetric dissipation of clouds per unit area over the location of the ground station with the rainfall recorded at that station shows a linear relationship for rainfall mounts exceeding 8 mm. The ratio of observed rainfall at the ground station over the satellite observed cloud volume dissipation per unit area was also computed. The result shows that the ratio is almost constant with the value of 9.55 mm/(pixel . km/pixel) for rainfall amounts exceeding 15 mm; and the variation is less then 10 percent for rainfall mounts between 8 and 15 mm. Needless to say, further investigation is required to verify this ratio.

Hung, R. J.; Smith, R. E.; West, G. S.

1985-01-01

15

Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project  

Microsoft Academic Search

The Convective Storm Initiation Project (CSIP) took place during the summers of 2004 and 2005, centred on the research radar at Chilbolton, UK. Precursors to convec- tive precipitation were studied, using a comprehensive and broad-based range of fieldwork and modelling. The princi- pal aim of CSIP was the detection of the primary and sec- ondary initiation of convective cells. The

K. M. Beswick; M. W. Gallagher; A. R. Webb; E. G. Norton; F. Perry

2008-01-01

16

Severe local convective storms in Bangladesh: Part I. Climatology  

NASA Astrophysics Data System (ADS)

This paper presents the climatology of severe local convective storms in Bangladesh. We collected sufficient severe local convective storm events over a long period (2,324 events from 1990 to 2005) to compile reliable climatological statistics by surveying the literature. Severe local convective storms frequently occur during the pre-monsoon season from March to May, peaking in April. The highest frequency was found to be at 16-17 Local Standard Time (LST) and 20-21 LST, with lower activity around midnight and early morning. It was also found that the occurrence of severe local convective storms is more concentrated in the central region of Bangladesh, and tends to spread northward during the pre-monsoon season.

Yamane, Yusuke; Hayashi, Taiichi; Dewan, Ashraf Mahmmood; Akter, Fatima

2010-03-01

17

A Convective Storm Matrix: Buoyancy/Shear Dependencies  

NSDL National Science Digital Library

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.

Comet

2003-04-09

18

Observations of Florida Convective Storms Using Dual Wavelength Airborne Radar  

NASA Technical Reports Server (NTRS)

NASA conducted the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE) during July 2002 for improved understanding of tropical cirrus. One of the goals was to improve the understanding of cirrus generation by convective updrafts. The reasons why some convective storms produce extensive cirrus anvils is only partially related to convective instability and the vertical transport ice mass by updrafts. Convective microphysics must also have an important role on cirrus generation, for example, there are hypotheses that homogeneous nucleation in convective updrafts is a major source of anvil ice particles. In this paper, we report on one intense CRYSTAL- FACE convective case on 16 July 2002 that produced extensive anvil.

Heymsfield, G. M.; Heymsfield, A. J.; Belcher, L.

2004-01-01

19

The three-dimensional morphology of simulated and observed1 convective storms over southern England2  

E-print Network

. The modelled storms23 were surrounded by a region of drizzle without ice reflectivities above 0 dBZ aloftThe three-dimensional morphology of simulated and observed1 convective storms over southern England observations of convective storms has been collected to evaluate12 such storms in the UK Met O ce Unified Model

Plant, Robert

20

Modes of Isolated, Severe Convective Storm Formation along the Dryline  

Microsoft Academic Search

Patterns of the formation of isolated, severe convective storms along the dryline in the Southern plains of the United States during the spring over a 16-year period were determined from an examination of the evolution of radar echoes as depicted by WSR-57 microfilm data. It was found that in the first 30 min after the first echo, more than half

Howard B. Bluestein; Stephen S. Parker

1993-01-01

21

Late-summer Martian Dust Storm  

NASA Technical Reports Server (NTRS)

This is an image of Mars taken from orbit by the Mars Reconnaissance Orbiter's Mars Color Imager (MARCI). The Red Planet's polar ice-cap is in the middle of the image. Captured in this image is a 37,000 square-kilometer (almost 23,000 miles) dust storm that moved counter-clockwise through the Phoenix landing site on Oct 11, 2008, or Sol 135 of the mission.

Viewing this image as if it were the face of a clock, Phoenix is shown as a small white dot, located at about 10 AM. The storm, which had already passed over the landing site earlier in the day, is located at about 9:30 AM.

2008-01-01

22

MOIST CONVECTIVE STORMS IN THE ATMOSPHERES OF JUPITER AND SATURN Atmospheric storms in Jupiter and Saturn  

Microsoft Academic Search

Moist convective storms might be a key constituent of the global energy budget in the atmospheres of the Giant Planets. The\\u000a storms extract their energy from the release of latent heat produced in the condensation of water which is only abundant hundreds\\u000a of kilometers below the observable cloud deck. Because these atmospheres are made of hydrogen and helium, dry air

Ricardo Hueso; Agustín S´nchez-Lavega

23

Characteristics of Extreme Summer Convection over equatorial America and Africa  

NASA Astrophysics Data System (ADS)

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.

Zuluaga, M. D.; Houze, R.

2013-12-01

24

A-Train Observations of Deep Convective Storm Tops  

NASA Technical Reports Server (NTRS)

The paper highlights simultaneous observations of tops of deep convective clouds from several space-borne instruments including the Moderate Resolution Imaging Spectroradiometer (MODIS) of the Aqua satellite, Cloud Profiling Radar (CPR) of the CloudSat satellite, and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) flown on the CALIPSO satellite. These satellites share very close orbits, thus together with several other satellites they are referred to as the "A-Train" constellation. Though the primary responsibility of these satellites and their instrumentation is much broader than observations of fine-scale processes atop convective storms, in this study we document how data from the A-Train can contribute to a better understanding and interpretation of various storm-top features, such as overshooting tops, cold-U/V and cold ring features with their coupled embedded warm areas, above anvil ice plumes and jumping cirrus. The relationships between MODIS multi-spectral brightness temperature difference (BTD) fields and cloud top signatures observed by the CPR and CALIOP are also examined in detail to highlight the variability in BTD signals across convective storm events.

Setvak, Martin; Bedka, Kristopher; Lindsey, Daniel T.; Sokol, Alois; Charvat, Zdenek; Stastka, Jindrich; Wang, Pao K.

2013-01-01

25

The Dynamics of Simulated Convective Storms in Hurricane Environments.  

NASA Astrophysics Data System (ADS)

Numerical simulations of convection in selected hurricane environments show that supercell storms are possible, even when buoyancy is relatively small. In one simulated supercell, the dynamic pressure force is found to reach a maximum about three times as strong as that of buoyancy in the late stages of the simulation. Updrafts reach peak intensity at low levels, often around 2-3 km AGL, and may exceed magnitudes expected from consideration of moist CAPE alone. Interactions between updraft and ambient vertical shear, and, later, growing contributions from vorticity, appear to dominate the development of the dynamic pressure field. Although the weak buoyancy tends to restrict storm intensity, a favorable matching of the vertical distribution of buoyancy with that of the vertical shear allows the pressure forces to become strong enough to take up the slack. Terms in the disturbance kinetic energy budget are correspondingly more strongly influenced by pressure effects than by buoyancy. Although the simulated supercells display the very strong, organized rotation characteristic of tornadic storms, many of the multicell storms which appear in the simulations also contain local concentrations of vorticity intense enough to suggest tornado potential. Simulations with differing background rotation (Coriolis) rates "f" show that convection which was multicellular at low f can become supercellular at higher f. The enhanced vertical vorticity that develops naturally in decaying tropical cyclones when angular momentum disperses under the influence of weakening pressure gradients may, by analogy, help explain why dissipating tropical cyclones are an especially fertile breeding ground for tornadic storms. Test simulations in which surface drag and a slightly modified subgrid mixing formulation were used show that the details of storm behavior can be quite sensitive to changes in these model parameters, although updraft and vorticity statistics are not altered greatly. In general, predictability appears to be reduced in these very moist environments.

McCaul, Eugene Williamson, Jr.

26

Observations of Florida Convective Storms using Dual Wavelength Airborne Radar  

NASA Technical Reports Server (NTRS)

NASA conducted the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE) during July 2002 for improved understanding of tropical cirrus. One of the goals was to improve the understanding of cirrus generation by convective updrafts. The reasons why some convective storms produce extensive cirrus anvils is only partially related to convective instability and the vertical transport ice mass by updrafts. Convective microphysics must also have an important role on cirrus generation, for example, there are hypotheses that homogeneous nucleation in convective updrafts is a major source of anvil ice particles. In this paper, we report on one intense CRYSTAL-FACE convective case on 16 July 2002 that produced extensive anvil. During CRYSTAL-FACE, up to 5 aircraft flying from low- to high-altitudes, were coordinated for the study of thunderstorm-generated cirrus. The NASA high-altitude (20 km) ER-2 aircraft with remote sensing objectives flew above the convection, and other aircraft such as the WB-57 performing in situ measurements flew below the ER-2. The ER-2 remote sensing instruments included two nadir viewing airborne radars. The CRS 94 GHz radar and the EDOP 9.6 GHz radar were flown together for the first time during CRYSTAL-FACE and they provided a unique opportunity to examine the structure of 16 July case from a dual-wavelength perspective. EDOP and CRS are complementary for studying convection and cirrus since CRS is more sensitive than EDOP for cirrus, and EDOP is considerably less attenuating in convective regions. In addition to the aircraft, coordinated ground-based radar measurements were taken with the NPOL S-Band (3 GHz) multiparameter radar. One of the initial goals was to determine whether dual-wavelength airborne measurements could identify supercooled water regions.

Heymsfield, G. M.; Heymsfield, A. J.; Belcher, L.

2004-01-01

27

Global-scale observations of ionospheric convection during geomagnetic storms  

NASA Astrophysics Data System (ADS)

The global effects on the ionosphere during periods of intense geomagnetic activity associated with geomagnetic storms are investigated using the Super Dual Auroral Radar Network (SuperDARN). The influence of the main and recovery phases of geomagnetic storms on ionospheric properties such as backscatter occurrence rates, velocity distributions, and convection patterns are presented. The evolution of magnetosphere and ionosphere parameters during the storms did not depend on the origin of the storm (e.g., a coronal mass ejection or a corotating interaction region). Instead, there was a continuum of response to the intensity of the driver. For example, we found a clear relationship between the most negative value of the southward component of the interplanetary magnetic field (IMF Bz) and the most negative value of the Sym-H index, which marks the end of the main phase of a storm. This is one of the first superposed epoch studies that analyzes the sunward/antisunward line-of-sight velocity as a function of magnetic local time for geomagnetic storms of various intensities. In the noon sector, before and during the main phase of the storms, the SuperDARN radars recorded faster antisunward ionospheric plasma drifts together with a significant increase in the number of ionospheric echoes. This is consistent with the expected increase in soft particle precipitation in the noon sector and with the reconnection electric field that occurs when the IMF Bz is strongly negative, as is the case during the main phase of storms. The SuperDARN echo occurrence in the noon sector returned to prestorm values early in the recovery phase. The overall response was similar in the midnight sector, except that the peak echo occurrence for the most intense storms was limited to a narrower time interval centered on the end of the main phase. There were reductions in the strong antisunward flows near local midnight observed during the main phase and early in the recovery phase, particularly for the intense storm class. Strong electric fields are applied in the nightside ionosphere during storms, and the decameter structures from which SuperDARN scatter are more easily produced. However, in regions of energetic auroral precipitation and after a long exposure to strong electric fields, there is often a reduction in SuperDARN echoes due to absorption or changes in radio wave propagation.

Gillies, D. M.; McWilliams, K. A.; St. Maurice, J.-P.; Milan, S. E.

2011-12-01

28

A three-dimensional model of moist convection for the giant planets II: Saturn's water and ammonia moist convective storms  

Microsoft Academic Search

Moist convective storms constitute a key aspect in the global energy budget of the atmospheres of the giant planets. Among them, Saturn is known to develop the largest scale convective storms in the Solar System, the Great White Spots (GWS) which occur rarely and have been detected once every 30 years approximately. On the average, Saturn seems to show much

Ricardo Hueso; Agustín Sánchez-Lavega

2004-01-01

29

Empirical reconstruction of storm-time steady magnetospheric convection events  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

30

A Method for Diagnosing the Sources of Infrasound in Convective Storm Simulations DAVID A. SCHECTER  

E-print Network

or density perturbation, and Lfw is the free-wave operator for A that is known from sound propagation theoryA Method for Diagnosing the Sources of Infrasound in Convective Storm Simulations DAVID A. SCHECTER in a numerical simulation of a convective storm. The method is based on an exact acoustic wave equation

Schecter, David

31

Empirical reconstruction of storm time steady magnetospheric convection events  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

32

Formaldehyde Photochemistry in the Upper Troposphere in and Near Convective Storms During the DC3 Study  

NASA Astrophysics Data System (ADS)

The 2012 Deep Convective Clouds and Chemistry (DC3) campaign in the summer of 2012 provided an opportunity to study the impacts of deep convection on various reactive and soluble precursors of ozone and HOx radicals in the upper troposphere and lower stratosphere over North America. Formaldehyde (CH2O) is one such gas. Formaldehyde measurements on the NASA DC-8 aircraft by difference frequency generation infrared absorption spectroscopy (DFGAS) and laser-induced fluorescence along with DFGAS measurements on the NSF/NCAR GV aircraft were acquired in the inflow and outflow of numerous storms over the course of this study. An overview of these measurements with past measurements over the continental U.S. will be given for both context and to illustrate the magnitude of CH2O perturbations caused by deep continental convection. A number of case studies were identified for comparison of these measurements with the NASA Langley Lagrangian photochemical box model and the WRF-Chem model. The former is constrained by time varying observations of CH2O precursors in both the boundary layer and upper troposphere to determine the magnitude of CH2O produced by gas-phase photochemistry in both the storm core and the outflow at various times for different storm types. These determinations will be used as a constraint on CH2O scavenging efficiency results obtained by a 3-component mixture method and as a means to assess the magnitude of potential CH2O production mechanisms from other sources such as heterogeneous production when smoke plumes intercept clouds.

Fried, A.; Weibring, P.; Richter, D.; Walega, J.; Olson, J. R.; Crawford, J. H.; Diskin, G. S.; Sachse, G. W.; Hanisco, T. F.; Arkinson, H. L.; Barth, M. C.; Campos, T. L.; Flocke, F. M.; Apel, E. C.; Hornbrook, R. S.; Hall, S. R.; Bela, M. M.; Cantrell, C. A.; Blake, D. R.; Blake, N. J.

2013-12-01

33

The Importance of the Vertical Location of Aerosol Layers on Convective Storms  

NASA Astrophysics Data System (ADS)

Enhanced aerosol concentrations appear to influence a number of the aspects of convective storms including the strength of the convective updraft, the intensity of the cold pool, and the microphysical and radiative characteristics of the convective anvil. However, in order for such influences to occur, aerosols need to be effectively ingested by the storm system of interest. The vertical location of an aerosol layer impacting a convective storm may influence how effectively aerosol are ingested by the storm system, and hence the degree to which the ingested aerosol subsequently influence storm microphysical and radiative processes. Furthermore, if the aerosol species impacting the storm are effective at absorbing solar radiation, heating within the aerosol layer enhances atmospheric stability, the level of which will be dictated by where the aerosol layer is located. Enhanced static stability may have negative impacts on the initial development of the convection of interest. Convective storms developing within environments of the same aerosol optical depth may therefore respond differently to aerosol indirect forcing by virtue of where the aerosol layer is vertically located. In this talk, the results of various high-resolution, cloud-resolving simulations will be presented, in which the sensitivity to the vertical location of the aerosol source on the convective development, aerosol ingestion efficiency, and subsequent microphysical and radiative properties are investigated. Microphysical budgets and storm trajectories will form an integral part of the analysis.

van den Heever, Susan; Grant, Leah

2014-05-01

34

Plasmapause Convects to the Magnetopause During Halloween Solar Storm  

NSDL National Science Digital Library

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.

Bridgman, Tom; Williams, James; Shirah, Greg; Goldstein, Jerald

2004-12-15

35

Initiation of a convective dust storm over North India on 21 April 2010 inferred using satellite data  

NASA Astrophysics Data System (ADS)

Dust storms commonly occur during the pre-monsoon (summer) season in north and northwest parts of India. Characteristics of dust events of the pressure gradient type are well understood. However, comprehensive studies on mechanism of convective dust storms in India are few. A convective dust storm which occurred on 21 April 2010 in association with a western disturbance over North India was hence studied. In the absence of in situ data, we used available satellite data to study the event. Dust storm that occurred on 20 April 2010 on the surface of the Thar Desert transported dust to northern and northwestern parts of India (Rajasthan, Haryana, Delhi and some parts of Uttar Pradesh). This formed a background of aerosols that affected the thunderstorm formed in association with western disturbance and the strong updraft in the thunderstorm carried the dust lingering in the atmosphere to higher altitudes. Large amount of aerosols carried to higher altitude suppressed the chance of precipitation by affecting the cloud top microphysics. Enhancement in evaporation due to an increase in aerosol concentration and strong downdrafts during dissipation of the thunderstorm resulted in emission of dust particles which led to the convective dust event of 21 April 2010.

Desouza, Nirmala Devidas; Kurchania, Rajnish; Qureshi, Muhammad Shums

2013-10-01

36

Electrical Behavior of Downburst-Producing Convective Storms over the Western United States  

E-print Network

A great body of research literature pertaining to microburst generation in convective storms has focused on thermodynamic factors of the pre-convective environment as well as storm morphology as observed by radar imagery. Derived products based on GOES sounder data have been found to be especially useful in the study of thermodynamic environments. However, addressed much less frequently is the relationship between convective storm electrification, lightning phenomenology and downburst generation. Previous research in lightning production by convective storms has identified that electrification, phenomenology (i.e. flash rate, density), and polarity are dependent upon the thermodynamic structure of the ambient atmosphere, especially vertical moisture stratification. Thus, relevant parameters to describe the thermodynamic setting would include CAPE, due to its influence on updraft strength, and cloud liquid water content, due to its relationship to precipitation physical processes. It has already been addressed...

Pryor, K

2006-01-01

37

Severe convective storms and United States climate change in the latter half of the twentieth century  

Microsoft Academic Search

Severe local storms generated by atmospheric convection and enhanced by wind shear may increase in frequency within the United States, forced by increased surface temperature and other climate changes documented during the 20th Century. However, archives of thunderstorm and tornado events may not accurately represent the climate system, because storm reporting has been influenced by changing detection technologies, enhanced public

Diana Marie Derubertis

2003-01-01

38

Observed and Simulated Radiative and Microphysical Properties of Tropical Convective Storms  

NASA Technical Reports Server (NTRS)

Increases in the ice content, albedo and cloud cover of tropical convective storms in a warmer climate produce a large negative contribution to cloud feedback in the GISS GCM. Unfortunately, the physics of convective upward water transport, detrainment, and ice sedimentation, and the relationship of microphysical to radiative properties, are all quite uncertain. We apply a clustering algorithm to TRMM satellite microwave rainfall retrievals to identify contiguous deep precipitating storms throughout the tropics. Each storm is characterized according to its size, albedo, OLR, rain rate, microphysical structure, and presence/absence of lightning. A similar analysis is applied to ISCCP data during the TOGA/COARE experiment to identify optically thick deep cloud systems and relate them to large-scale environmental conditions just before storm onset. We examine the statistics of these storms to understand the relative climatic roles of small and large storms and the factors that regulate convective storm size and albedo. The results are compared to GISS GCM simulated statistics of tropical convective storms to identify areas of agreement and disagreement.

DelGenio, Anthony D.; Hansen, James E. (Technical Monitor)

2001-01-01

39

Exploring the Giant Saturnian Storm in 2010: A Model of Moist Convection  

NASA Astrophysics Data System (ADS)

A giant planet-encircling storm occurred on Saturn at the end of year 2010. The storm produced lightning at a rate greater than 10 SEDs per second. It stirred up its latitude band and wrapped around the planet, and after 6 months it died. These kinds of storms are rare and episodic. They happen every 20-30 years. In this study, we discuss the role of moist convection to the development of the storm. The study is composed of three parts. First, thermodynamics on Saturn suggests that strong convection is prohibited by the water-loading-effect when the troposphere is warm. After 20~30 years, the troposphere has cooled below a critical value so that deep convection starts to develop at the base of the cloud. Second, a linear perturbation analysis of Rossby waves in an easterly jet is performed to narrow down the choices of free parameters. Based on the observed features of the storm (propagation phase speed, typical wave length, etc), the Rossby radius of deformation is calculated to be around 2000 km. Third, a 2D numerical model is developed to simulate the propagation of the storm, with moist convection parameterized as an anticyclonic vorticity source. The simulated storm has a well-defined head and a wavy tail that resemble the observation.

Li, C.; Ingersoll, A. P.

2012-12-01

40

Review of the climate science for severe convective storms, extreme precipitation, hurricanes and typhoons, and severe snowstorms and ice storms shows that the ability to  

E-print Network

and typhoons, and severe snowstorms and ice storms shows that the ability to detect and attribute trends varies thunderstorms), 2) extreme precipitation, 3) hurri- canes and typhoons, and 4) severe snowstorms and ice stormsReview of the climate science for severe convective storms, extreme precipitation, hurricanes

Kossin, James P.

41

Initialization of a modeled convective storm using Doppler radar-derived fields  

NASA Technical Reports Server (NTRS)

A method is developed to initialize convective storm simulations with Doppler radar-derived fields. Input fields for initialization include velocity, rainwater derived from radar reflectivity, and pressure and temperature fields obtained through thermodynamic retrieval. A procedure has been developed to fill in missing wind data, followed by a variational adjustment to the filled wind field to minimize 'shocks' that would otherwise cause the simulated fields to deteriorate rapidly. A series of experiments using data from a simulated storm establishes the feasibility of the initialization method. Multiple-Doppler radar observations from the 20 May 1977 Del City tornadic storm are used for the initialization experiments. Simulation results are shown and compared to observations taken at a later time. The simulated storm shows good agreement with the subsequent observations, though the simulated storm appears to be evolving faster than observed. Possible reasons for the discrepancies are discussed.

Lin, Ying; Ray, Peter S.; Johnson, Kenneth W.

1993-01-01

42

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

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

43

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

E-print Network

1 HEAT TRANSFERS IN A DOUBLE SKIN ROOF VENTILATED BY NATURAL CONVECTION IN SUMMER TIME P. H radiation. Natural convection in the channel underneath drives off the residual heat. The bi: Double-skin roof; Radiation; Natural convection; Passive cooling; Solar loads. * Corresponding author

Boyer, Edmond

44

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

E-print Network

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

Collett Jr., Jeffrey L.

45

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

E-print Network

European climatology of severe convective storm environmental parameters: A test for significant Studies, Norman, OK, USA Accepted 22 June 2005 Abstract A climatology of various parameters associated. This process is a first step towards development of a synthetic climatology of European severe weather

Doswell III, Charles A.

46

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

NASA Astrophysics Data System (ADS)

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.

Ancell, Brian; Nauert, Christian

2014-05-01

47

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

E-print Network

Midweek increase in U.S. summer rain and storm heights suggests air pollution invigorates air pollution suppresses cloud-drop coalescence and early rainout during the growth of thunderstorms over land, allowing more water to be carried above the 0°C isotherm, where freezing yields additional

Daniel, Rosenfeld

48

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

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;

Wang, Deli

49

Pressure and Vorticity Transients from Summer Storms and Aircraft  

Microsoft Academic Search

A field study directed primarily to the pressure fields produced by thunderstorms, plumes, dust devils and aircraft has been conducted during several summers at locations in northeastern Colorado and near Stapleton International Airport, Denver. A 60 m tripartite array of anemometers plus sensors of pressure, vertical wind and vorticity were employed in the study of plumes and small vortices. The

A. Raymond Jordan

1980-01-01

50

Thermally Induced Compression Waves and Gravity Waves Generated by Convective Storms.  

NASA Astrophysics Data System (ADS)

A three-dimensional, fully compressible cloud model is used to simulate a convective storm in order to investigate the properties of compression waves and gravity waves induced by latent heat release. Time series of the low-level pressure perturbations caused by the propagating waves are examined at various distances from the storm. A compression wave that is close to hydrostatic balance and can be considered to be a Lamb wave, which propagates in the horizontal plane, emerges from the storm. This latter property gives the wave a distinctly two-dimensional character that is clarified by comparison with a linear model of a two-dimensional thermally induced compression wave. This has implications for its shape and results in a decay rate with distance propagated from the source of 1/(distance)1/2. The period of the Lamb wave is determined primarily by the time it takes for the storm to develop and decay. The fast-moving Lamb wave is trailed by slower-moving thermally induced gravity waves. It is found that the amplitude of the gravity waves decay with 1/distance. Distinct gravity wave modes can be identified. The first mode propagates the fastest and results in deep subsidence warming. The second mode propagates at half the speed of the first and causes weak low-level uplift, which in some convective situations might aid the development of new convection.An analysis of the transfer of internal and gravitational potential energies showed that the net transfer by the Lamb wave was approximately equal to the net increase of total energy in the atmosphere brought about by the convective storm. This result suggests that physical interpretations of total energy transfer in the atmosphere need to take into account that it can be transferred in a wavelike manner at the speed of sound.An interesting buoyancy oscillation occurred when the downdraft air overshot its buoyant equilibrium level, which resulted in a resurgence of convection. The convection was able to obtain moderate strength by feeding on moist environmental air that had been advected over the top of the cold pool. This mechanism may be a factor contributing to the early meso- convective cycle that has been observed in many convective systems.

Nicholls, Melville E.; Pielke, Roger A., Sr.

2000-10-01

51

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

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

52

Occurrence of summer and winter storms in GPS TEC during solar minimum period  

NASA Astrophysics Data System (ADS)

The GPS measurements collected by IGS/EPN over Europe were used to study of the ionosphere response to summer (July 2009) and winter (October 2008) storms. Analysis was based on behaviour of GPS TEC variations over individual GPS stations within 35-70N latitudes and GPS TEC maps created with high resolution. The features of spatial and temporal dynamics of the ionosphere during these storms were revealed in GPS TEC maps. It is necessary to note that considered storm were rather moderate (Dst¡70 nT) as were observed during extended solar minimum. For the case of October 2008 storm the well-pronounced positive effect was observed during day-time. Strong short-term TEC enhancement was detected near noon. The TEC enhancement exceeded 100

Shagimuratov, Irk; Krankowski, Andrzej; Zakharenkova, Irina; Tepenitsyna, Nadezhda; Yakimova, Galina

53

Observations of lightning in convective supercells within tropical storms and hurricanes  

SciTech Connect

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.

Lyons, W.A.; Keen, C.S. [Mission Research Corp., Fort Collins, CO (United States)] [Mission Research Corp., Fort Collins, CO (United States); [Mankato State Univ., Mankato, MN (United States)

1994-08-01

54

Simulating supercell thunderstorms in a convective boundary layer: Effects on storm and boundary layer properties  

NASA Astrophysics Data System (ADS)

Nearly all previous numerical simulations of supercell thunderstorms have neglected surface uxes of heat, moisture, and momentum as well as horizontal inhomogeneities in the near-storm environment from resulting dry boundary layer convection. This investigation uses coupled radiation and land-surface schemes within an idealized cloud model to identify the effects of organized boundary layer convection in the form of horizontal convective rolls (HCRs) on the strength, structure, and evolution of simulated supercell thunderstorms. The in uence of HCRs and the importance of their orientation relative to storm motion is tested by comparing simulations with a convective boundary layer (CBL) against those with a horizontally homogeneous base state having the same mean environment. The impact of anvil shading on the CBL is tested by comparing simulations with and without the effects of clouds in the radiative transfer scheme. The results of these simulations indicate that HCRs provide a potentially important source of environmental vertical vorticity in the sheared, near-storm boundary layer. These vorticity perturbations are amplified both beneath the main supercell updraft and along the trailing out ow boundary, leading to the formation of occasionally intense misovortices. HCRs perpendicular to storm motion are found to have a detrimental effect on the strength and persistence of the lowlevel mesocyclone, particularly during its initial development. Though the mean environment is less supportive of low-level rotation with a wind profile conducive to HCRs oriented parallel to storm motion, such HCRs are found to often enhance the low-level mesocyclone circulation. When anvil shading is included, stabilization results in generally weaker low-level mesocyclone circulation, regardless of HCR orientation. Moreover, HCRs diminish in the near-storm environment such that the effects of HCRs on the supercell are mitigated. HCRs are also shown to be a necessary condition for the formation of so-called "feeder clouds" and anking line convection in these simulations. These findings suggest potentially important rami fications regarding both non-mesocyclone and mesocyclone tornadoes in supercell thunderstorms in an environment with active boundary layer convection.

Nowotarski, Christopher J.

55

Sensitivity of the Amazon rainforest to convective storms  

NASA Astrophysics Data System (ADS)

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.

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

56

The Impact of Vegetation on the Atmospheric Boundary Layer and Convective Storms  

Microsoft Academic Search

The impact of vegetation on atmospheric boundary layer and convective storms is examined through the construction and testing of a soil-vegetation-atmosphere transfer (SVAT) model. The Land Ecosystem-Atmosphere (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

Tsengdar John Lee

1992-01-01

57

Study of Ardmore, Oklahoma storm clouds. I - Convective storm cloud initiation and development based on the remote sensing gravity-wave-induced convection. II - Satellite infrared remote sensing and numerical simulation  

NASA Technical Reports Server (NTRS)

The role of gravity waves is discussed with respect to the vertical velocity of convection. Specific attention is given to wave-induced convection which contributes to the fractions of formation and the development of severe convective storms. Large-amplitude gravity waves and convective instability were investigated in storm clouds above Ardmore, Oklahoma. Rapid-scan satellite imagery and radar summaries provide evidence of water-vapor condensation related to convection which is introduced by gravity waves. Gravity wave periods of 35 minutes are found to initiate weak convection, which can be intensified by gravity waves with periods of 20 minutes. The convective motion reaches a maximum about one hour before funnel clouds develop. Other mechanisms which contribute to convective motion are considered, but gravity waves are the major contributor to the initiation, formation, and development of mesoscale storm clouds. Cloud modeling based on satellite imagery and sounding data showed that by overshooting cloud tops that penetrated the tropopause, storm clouds mature; that these clouds collapse about 9 minutes before the touchdown of tornadoes; and that cloud tops collapse at a high rate about 6 minutes before tornadoes lift off.

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

1991-01-01

58

Organization of Oceanic Convection during the Onset of the 1998 East Asian Summer Monsoon  

E-print Network

by a major shift in the circulation over the east Asian region. Analysis of Bureau of Meteorology ResearchOrganization of Oceanic Convection during the Onset of the 1998 East Asian Summer Monsoon RICHARD H. Introduction The east Asian monsoon (EAM) is characterized by distinctly different winter and summer

Johnson, Richard H.

59

Mechanism for northward propagation of boreal summer intraseasonal oscillation: Convective momentum transport  

E-print Network

Mechanism for northward propagation of boreal summer intraseasonal oscillation: Convective momentum to understand the role of CMT in the northward prop- agation of ISO. The basic mechanism of northward propa: Kang, I.-S., D. Kim, and J.-S. Kug (2010), Mechanism for northward propagation of boreal summer intra

60

The importance of storm time steady magnetospheric convection in determining the final relativistic electron flux level  

NASA Astrophysics Data System (ADS)

electrons pose a space weather hazard to satellites in the radiation belts. Although about half of all geomagnetic storms result in relativistic electron flux enhancements, other storms decrease relativistic electron flux, even under similar solar wind drivers. Radiation belt fluxes depend on a complex balance between transport, loss, and acceleration. A critically important aspect of radiation belt enhancements is the role of the "seed" population—plasma sheet particles heated and transported earthward by magnetotail processes—which can become accelerated by wave-particle interactions with chorus waves. While the effect of substorms on seed electron injections has received considerable focus, in this study we present a previously unexplored connection between quasi-steady convection during steady magnetospheric convection (SMC) events and the transport and energization of electrons. SMC events are long-duration intervals of enhanced convection without any substorm expansions and are an important mechanism in coupling magnetotail plasma populations to the inner magnetosphere. We find that storms with SMCs in the recovery phase are more likely to increase relativistic electron flux levels, while storms without SMCs are more likely to result in a decrease. Using particle measurements from the Time History of Events and Macroscale Interactions During Substorms mission, we show that phase space density of seed electron populations increases 1 h before SMC start and stays elevated through the duration of SMCs. Chorus activity is also elevated during SMC events. These results suggest that rather than hindering electron acceleration by diverting plasma away from the inner magnetosphere, SMC events appear to act to enhance and maintain seed electron populations.

Kissinger, Jennifer; Kepko, Larry; Baker, Daniel N.; Kanekal, Shri; Li, Wen; McPherron, Robert L.; Angelopoulos, Vassilis

2014-09-01

61

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

E-print Network

://hwt.nssl.noaa.gov)]. These convection-allowing models can develop storms with unique attributes permitting forecasters to interrogate with the advancement of storm-scale models and data assimilation techniques, forecast quality is hindered by limited

62

The Impact of Microphysics and Planetary Boundary Layer Physics on Model Simulation of U.S. Deep South Summer Convection  

NASA Technical Reports Server (NTRS)

Inspection of output from various configurations of high-resolution, explicit convection forecast models such as the Weather Research and Forecasting (WRF) model indicates significant sensitivity to the choices of model physics pararneterizations employed. Some of the largest apparent sensitivities are related to the specifications of the cloud microphysics and planetary boundary layer physics packages. In addition, these sensitivities appear to be especially pronounced for the weakly-sheared, multicell modes of deep convection characteristic of the Deep South of the United States during the boreal summer. Possible ocean-land sensitivities also argue for further examination of the impacts of using unique ocean-land surface initialization datasets provided by the NASA Short-term Prediction Research and Transition (SPoRn Center to select NOAAlNWS weather forecast offices. To obtain better quantitative understanding of these sensitivities and also to determine the utility of the ocean-land initialization data, we have executed matrices of regional WRF forecasts for selected convective events near Mobile, AL (MOB), and Houston, TX (HGX). The matrices consist of identically initialized WRF 24-h forecasts using any of eight microphysics choices and any of three planetary boWldary layer choices. The resulting 24 simulations performed for each event within either the MOB or HGX regions are then compared to identify the sensitivities of various convective storm metrics to the physics choices. Particular emphasis is placed on sensitivities of precipitation timing, intensity, and coverage, as well as amount and coverage oflightuing activity diagnosed from storm kinematics and graupel in the mixed phase layer. The results confirm impressions gleaned from study of the behavior of variously configured WRF runs contained in the ensembles produced each spring at the Center for the Analysis and Prediction of Storms, but with the benefit of more straightforward control of the physics package choices. The design of the experiments thus allows for more direct interpretation of the sensitivities to each possible physics combination. The results should assist forecasters in their efforts to anticipate and correct for possible biases in simulated WRF convection patterns, and help the modeling community refine their model parameterizations.

McCaul, Eugene W., Jr.; Case, Jonathan L.; Zavodsky, Bradley T.; Srikishen, Jayanthi; Medlin, Jeffrey M.; Wood, Lance

2014-01-01

63

The Impacts of Microphysics and Planetary Boundary Layer Physics on Model Simulations of U. S. Deep South Summer Convection  

NASA Technical Reports Server (NTRS)

Inspection of output from various configurations of high-resolution, explicit convection forecast models such as the Weather Research and Forecasting (WRF) model indicates significant sensitivity to the choices of model physics parameterizations employed. Some of the largest apparent sensitivities are related to the specifications of the cloud microphysics and planetary boundary layer physics packages. In addition, these sensitivities appear to be especially pronounced for the weakly-sheared, multicell modes of deep convection characteristic of the Deep South of the United States during the boreal summer. Possible ocean-land sensitivities also argue for further examination of the impacts of using unique ocean-land surface initialization datasets provided by the NASA Short-term Prediction Research and Transition (SPoRT Center to select NOAA/NWS weather forecast offices. To obtain better quantitative understanding of these sensitivities and also to determine the utility of the ocean-land initialization data, we have executed matrices of regional WRF forecasts for selected convective events near Mobile, AL (MOB), and Houston, TX (HGX). The matrices consist of identically initialized WRF 24-h forecasts using any of eight microphysics choices and any of three planetary boundary layer choices. The resulting 24 simulations performed for each event within either the MOB or HGX regions are then compared to identify the sensitivities of various convective storm metrics to the physics choices. Particular emphasis is placed on sensitivities of precipitation timing, intensity, and coverage, as well as amount and coverage of lightning activity diagnosed from storm kinematics and graupel in the mixed phase layer. The results confirm impressions gleaned from study of the behavior of variously configured WRF runs contained in the ensembles produced each spring at the Center for the Analysis and Prediction of Storms, but with the benefit of more straightforward control of the physics package choices. The design of the experiments thus allows for more direct interpretation of the sensitivities to each possible physics combination. The results should assist forecasters in their efforts to anticipate and correct for possible biases in simulated WRF convection patterns, and help the modeling community refine their model parameterizations.

McCaul, E. W., Jr.; Case, J. L.; Zavodsky, B. T.; Srikishen, J.; Medlin, J. M.; Wood, L.

2014-01-01

64

Ionospheric convection during the magnetic storm of 20-21 March 1991  

NASA Technical Reports Server (NTRS)

We report on the response of high-latitude ionospheric convection during the magnetic storm of March 20-21 1990. IMP-8 measurements of solar wind plasma and interplanetary magnetic field (IMF), ionospheric convection flow measurements from the Wick and Goose Bay coherent radars, EISCAT, Millstone Hill and Sondrestorm incoherent radars and three digisondes at Millstone Hill, Goose Bay and Qaanaaq are presented. Two intervals of particular interest have been indentified. The first starts with a storm sudden commencement at 2243 UT on March 20 and includes the ionospheric activity in the following 7 h. The response time of the ionospheric convection to the southward tuning of the IMF in the dusk to midnight local times is found to be approximately half that measured in a similar study at comparable local times during more normal solar wind conditions. A subsequent reconfiguration of the nightside convection pattern was also observed, although it was not possible to distinguish between effects due to possible changes in B(sub y) and effects due to substorm activity. The second interval, 1200-2100 UT 21 March 1990, included a southward turning of the IMF which resulted in the B(sub z) component becoming -10 nT. The response time on the dayside to this change in the IMF at the magnetopause was approximately 15 min to 30 min which is a factor of approximately 2 greater than those previously measured at higher latitudes. A movement of the nightside flow reversal, possibly driven by current systems associated with the substorm expansion phases, was observed, implying that the nightside convection pattern can be dominated by substorm activity.

Taylor, J. R.; Yeoman, T. K.; Lester, M.; Buonsanto, M. J.; Scali, J. L.; Ruohoniemi, J. M.; Kelly, J. D.

1994-01-01

65

Midweek Increase in U.S. Summer Rain and Storm Heights, Suggests Air Pollution Invigorates Rainstorms  

NASA Technical Reports Server (NTRS)

Tropical Rainfall Measuring Mission (TRMM) satellite data show a significant midweek increase in summertime rainfall over the southeast U.S., due to afternoon intensification. TRMM radar data show a significant midweek increase in rain area and in the heights reached by afternoon storms. Weekly variations in model-reanalysis wind patterns over the region and in rain-gauge data are consistent with the satellite data. A midweek decrease of rainfall over the nearby Atlantic is also seen. EPA measurements of particulate concentrations show a midweek peak over much of the U.S. These observations are consistent with the theory that anthropogenic air pollution suppresses cloud-drop coalescence and early rainout during the growth of thunderstorms over land, allowing more water to be carried above the 0 C isotherm, where freezing yields additional latent heat, invigorating the storms--most dramatically evidenced by the shift in the midweek distribution of afternoon-storm heights--and producing large ice hydrometeors. The enhanced convection induces regional convergence, uplifting and an overall increase of rainfall. Compensating downward air motion suppresses convection over the adjacent ocean areas. Pre-TRMM-era data suggest that the weekly cycle only became strong enough to be detectable beginning in the 1980's. Rain-gauge data also suggest that a weekly cycle may have been detectable in the 1940's, but with peak rainfall on Sunday or Monday, possibly explained by the difference in composition of aerosol pollution at that time. This "weekend effect" may thus offer climate researchers an opportunity to study the regional climate-scale impact of aerosols on storm development and monsoon-like circulation.

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

2007-01-01

66

Satellite infrared imagery, rawinsonde data, and gravity wave remote sensing of severe convective storms  

NASA Technical Reports Server (NTRS)

GOES digital infrared data during the time period between two hours before the touchdown of tornado and the tornado touchdown time were used in this study. Comparison between tornado-associated clouds and non-tornado-associated clouds indicates that the difference between overshooting cloud top temperature and the tropopause temperature, or how much the cloud has penetrated above the tropopause, rather than either the absolute temperature of penetrative cloud top or the height of the top of overshooting turret is significant for the possible formation of severe storms. The penetrative overshooting cloud top collapses about 15 to 30 minutes before the touchdown of tornado. Gravity waves were detected from the severe convective storms.

Hung, R. J.; Smith, R. E.

1982-01-01

67

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

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

68

An estimation of the condensation rates in three severe storm systems from satellite observations of the convective mass flux  

NASA Technical Reports Server (NTRS)

A technique was developed for estimating the condensation rates of convective storms using satellite measurements of cirrus anvil expansion rates and radiosonde measurements of environmental water vapor. Three cases of severe convection in Oklahoma were studied and a diagnostic model was developed for integrating radiosonde data with satellite data. Two methods were used to measure the anvil expansion rates - the expansion of isotherm contours on infrared images, and the divergent motions of small brightness anomalies tracked on the visible images. The differences between the two methods were large as the storms developed, but these differences became small in the latter stage of all three storms. A comparison between the three storms indicated that the available moisture in the lowest levels greatly affected the rain rates of the storms. This was evident from both the measured rain rates of the storms and the condensation rates estimated by the model. The possibility of using this diagnostic model for estimating the intensities of convective storms also is discussed.

Mack, R. A.; Wylie, D. P.

1982-01-01

69

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

E-print Network

in creating specifi. c regions within the large-scale synoptic field where the release of instability resulted in convection. Lewis et al. (1974) examined a specific case of squall line formation within an area of large-scale upslope motion above a frontal... wave. In addition, a squall line containing heavy to severe thunder- storms developed at 0600 GMT, 12 May 1974 from southeast Georgia southwestward into the Gulf of Mexico. Maximum radar tops along the squall line were above 55, 000 ft. 4...

Wilson, Gregory Sims

2012-06-07

70

Severe convective storms initiated by intense wildfires: Numerical simulations of pyro-convection and pyro-tornadogenesis  

NASA Astrophysics Data System (ADS)

On the afternoon of 18 January 2003, wildfires swept through several outer suburbs of Canberra (Australia) producing, inter alia, a series of large pyro-cumulonimbus cells and at least one tornado. The results of a large-eddy simulation with a parameterized fire are reported here. The simulation, motivated by the Canberra wildfires and severe storms, captures the main characteristics of the observed pyro-cumulonimbi, including the formation of a tornado close to where one was observed. In addition, the model develops prominent horizontally oriented vortices on the western side of the fire in the direction of the low-level shear, and a series of horizontally oriented vortices on the upstream side of the convection column. The production of water by the fire is critical for the development of a pyro-cumulonimbus cell intense enough to reach the tropopause as observed and plays a significant role in the associated tornadogenesis.

Cunningham, Philip; Reeder, Michael J.

2009-06-01

71

Gravity shear waves atop the cirrus layer of intense convective storms  

NASA Technical Reports Server (NTRS)

Recent visual satellite photographs of certain intense convective storms have revealed concentric wave patterns. A model for the generation and growth of these waves is proposed. The proposed initial generating mechanism is similar to the effect noticed when a pebble is dropped into a calm pond. The penetration of the tropopause by overshooting convection is analogous to the pebble's penetration of the water's surface. The model for wave growth involves instability due to the wind shear resulting from the cirrus outflow. This model is based on an equation for the waves' phase speed which is similar to the Helmholtz equation. It, however, does not assume an incompressible atmosphere, but rather assumes density is a logarithmic function of height. Finally, the model is evaluated on the two mid-latitude and three tropical cases. The data indicate that shearing instability may be a significant factor in the appearance of these waves.

Stobie, J. G.

1975-01-01

72

Documentary evidence on strong winds related to convective storms in the Czech Republic since AD 1500  

NASA Astrophysics Data System (ADS)

This article summarizes information about the occurrence of strong winds connected with convective storms in the Czech Republic for the last 500 years obtained on the basis of the study of historical documentary sources. Documentary evidence about strong winds is characterized with respect to its advantages and drawbacks. Principles are stated for setting up the database of strong winds and the classification of those cases from the point of view of the type of the phenomenon, extent and character of the damage caused. The chronology of strong winds is presented since AD 1500 with particular respect to the occurrence of tornadoes. For tornadoes, their occurrence during the year is analyzed, as well as their dimensions, intensity and the character of the damage caused. All cases of tornadoes, so far recorded in the Czech Republic, are listed and characterized in the appendix. The impacts of strong winds during convective storms and tornadoes are evaluated. The importance of documentary evidence about strong winds from pre-instrumental period is pointed out.

Dobrovolný, Petr; Brázdil, Rudolf

73

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

NASA Technical Reports Server (NTRS)

Observational requirements for predicting convective storm development and intensity as suggested by recent numerical experiments are examined. Recent 3D numerical experiments are interpreted with regard to the relationship between overshooting tops and surface wind gusts. The development of software for emulating satellite inferred cloud properties using 3D cloud model predicted data and the simulation of Heymsfield (1981) Northern Illinois storm are described as well as the development of a conceptual/semi-quantitative model of eastward propagating, mesoscale convective complexes forming to the lee of the Rocky Mountains.

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

1982-01-01

74

Sprite-producing Convective Storms within the Colorado Lightning Mapping Array  

NASA Astrophysics Data System (ADS)

The multi-year, multi-institution effort entitled Physical Origins of Coupling to the Upper Atmosphere from Lightning (PhOCAL), has among its goals to qualitatively understand the meteorology and lightning flash characteristics that produce the unusual and/or very energetic lightning responsible for phenomena such as sprites, halos, elves, blue jets and gigantic jets, collectively known as Transient Luminous Events (TLEs). A key task is to obtain simultaneous video, ideally with a high-speed imager (HSI), of both a TLE and its parent lightning discharge, within the domain of a 3-D Lightning Mapping Array (LMA). While conceptually simple, this task is logistically quite complicated. In 2012, a new 15-station Colorado LMA (COLMA) became operational, covering northeastern Colorado, with the Yucca Ridge Field Station (YRFS) near its western edge. The National Charge Moment Change Network (CMCN), which since 2007 has been documenting sprite-class +CGs (those with impulse change moment changes >100 C km), indicates that a strong gradient of energetic +CGs exists west-to-east through the COLMA, with the most likely region for sprite-producing storms being in the COLMA eastern fringes (western Kansas and Nebraska). Yet, on 8 and 25 June, 2012, intense convective systems formed in the COLMA along and just east of the Front Range, producing severe weather and intense lightning. On the 8th, four sprite parent +CGs were captured at 3000 fps from YRFS with the sprites confirmed by dual (conventional speed) cameras in New Mexico. In a second storm on the 25th, viewing conditions prevented +CG video acquisition, but sprites were logged over the COLMA and detailed reconstructions of the discharges are being made. The parent discharges often began as upward negative leaders propagating into a mid-level positive charge layer at 8-10 km. They often originated within or near the convective core before expanding outward into a stratiform region and involving several hundred square kilometers, to be followed by +CG and strong continuing currents. LMA indications of recoil leaders appear confirmed by some high-speed video. These storms were somewhat smaller than the typical sprite-bearing MCS. The storm structures will be categorized using GOES IR, NEXRAD reflectivity, NLDN lightning data, CMCN impulse charge moment data, and full charge moment charge retrievals. The sprite parent CG discharges will be cataloged along with their points of origin, the height and volume from which charge is removed, the charge lowered to ground, and the continuing current characteristics. These CGs will be placed in the context of the storms' meteorological structure and evolution.

Lyons, W. A.; Cummer, S. A.; Rison, W.; Krehbiel, P. R.; Lang, T. J.; Rutledge, S. A.; Lu, G.; Stanley, M. A.; Ashcraft, T.; Nelson, T. E.

2012-12-01

75

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

E-print Network

P1.22 A FIVE-YEAR CLIMATOLOGY OF ELEVATED SEVERE CONVECTIVE STORMS IN THE UNITED STATES EAST's (1990a) climatology. Colman (1990a) found that elevated deep convection typically occurs north-air advection. His climatology also showed that nearly all winter- season storms are elevated, and a smaller

Schultz, David

76

Assessment of the European Severe Convective Storm Climatology using Reanalysis Data  

NASA Astrophysics Data System (ADS)

Thunderstorms and their accompanying phenomena like large hail, severe wind gusts, tornadoes and excessive precipitation are increasingly recognized as an important hazard to life and property in Europe. Within the project STEPCLIM ("Severe Thunderstorm Evaluation and Predictability in Climate Models"), we link historic severe thunderstorm events in Europe to atmospheric conditions resolved by reanalysis data. The aim is to find a relation between quantities, which can be represented by relatively coarse climate models, and the occurrence of short-lived and local severe weather phenomena associated with convection. At a later stage, this relation will be applied to climate forecast data, so that the effects of climate change on the frequency and intensity of severe convective storms can be investigated. A set of parameters is defined for the characterization of the local state of the atmosphere at any given point in place and time. These parameters represent the "ingredients" for severe thunderstorms, namely instability, vertical wind shear, and a measure of support for convective initiation. They are calculated from 6-hourly ERA-Interim reanalysis fields (1979-2011). The such derived fields are compared with the occurrence or non-occurrence of severe weather phenomena according to the quality-controlled severe storm reports collected in the European Severe Weather Database (ESWD). A logistic regression is then fitted in order to find the best relation between a given combination of parameters and the associated severe weather probability. This relation is postulated to be invariant against any changes in climate, an assumption that is justified by the physics-based nature of the chosen parameters. With this restriction, the derived relation can be used to estimate future severe weather frequencies based on modeled climatic changes of the underlying parameter distributions. In this presentation, emphasis is put on the used methodology and on a way to deal with spatial and temporal inhomogeneities of the observational data.

Pistotnik, Georg; Groenemeijer, Pieter; Kühne, Thilo

2013-04-01

77

A Sensitivity Study of East Asian Summer Monsoon to convective parameters in WRF regional climate model  

NASA Astrophysics Data System (ADS)

It is a challenging task to capture East Asian Summer Monsoon (EASM) in current climate modeling. In this study, we examined the sensitivity of simulated EASM precipitation and associated monsoon components to several convection related parameters using the WRF regional climate model. The results show that summer mean precipitation amount and pattern exhibit significant response to several parameters. The West Pacific Subtropical High (WPSH) is also affected by the modified convection through the diabatic heating, which further modulate the precipitation. The model can reasonably reproduce the northward propagation and transition of rain belt, which is also sensitive to those convective parameters. Previous study suggested summer precipitation over contiguous China has large diurnal variations with regional features. The diurnal cycle of summer precipitation over Yangzi River Delta has two peaks at early morning and late afternoon, which are connected with the stratiform and convective precipitation, respectively. In this study, we also investigated the sensitivity of diurnal cycle and extremes PDF of monsoon precipitation to those parameters.

Yang, B.; Zhang, Y.; Qian, Y.

2012-12-01

78

Doppler radar observations of the evolution of a small convective storm during Cohmex. [Cooperative Huntsville Meteorological Experiment  

NASA Technical Reports Server (NTRS)

Doppler radar observations of a deep convection that developed along the Alabama-Tennesse border on July 14, 1986 are analyzed. The evolution and structure of the convective storm are examined. Two convective cores are observed and both having a radius of about 1 km and maximum reflectivities of about 5 dBz; a third cell is also detected later in the region between the northern and southern cells. It is noted that the northern cell is the most dominant possessing an updraft through the region of maximum reflectivity. Diagrams of the vertical structure of the cells are provided.

Moore, Patrick D.; Ray, Peter S.

1989-01-01

79

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

SciTech Connect

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.

Lee, T.J.

1992-01-01

80

Multiparameter Radar Measurements in Colorado Convective Storms. Part I: Graupel Melting Studies.  

NASA Astrophysics Data System (ADS)

This paper presents an analysis of coordinated measurements taken by the NCAR CP-2 radar and the Wyoming King Air aircraft flown by NCAR during the May Polarization Experiment, which was held new Boulder, Colorado. A key feature of this paper is the rigorous computation Of ZH, ZDR and LDR using an electromagnetic model that is coupled to a detailed one-dimensional microphysical model of melting graupel. The graupel melting model was initialized with aircraft-measured graupel spectrum and sounding data. Two case studies during MAYPOLE '83 were considered where model-derived vertical profiles of ZH and ZDR were computed and compared to radar measurements, resulting in excellent agreement. The RHI profiles of ZH, ZDR and LDR through the core of an isolated convective storm revealed new and interesting microphysical data which are consistent with model computations. The radar measurements and model results of this paper show that a significant breakthrough has been made in the radar remote sensing of storm microphysics.

Bringi, V. N.; Rasmussen, R. M.; Vivekanandan, J.

1986-11-01

81

Field Line Resonance Measurements in the Inner Magnetosphere During Large Storms: Implications for Convection and Depletion  

NASA Astrophysics Data System (ADS)

Field Line Resonances (FLRs) have been shown to be an effective way to remote sense plasmaspheric mass density. In the outer plasmasphere the mass density is modeled well by a power-law distribution and solutions have been tabulated that allow the direct conversion between resonance frequency and mass density. In the inner plasmasphere, for L<3, plasma density is not modeled by a power law and the resonance equation must be solved directly using a model plasma density. We use the time-dependent Field Line Interhemispheric Plasma (FLIP) model and solve the resonance equation with a finite element method. We compare the solutions with FLR measurements from several magnetometer chains in both the northern and southern hemisphere in the American sector, South American Meridional B-field Array (SAMBA), Magnetometers along the Eastern Atlantic Seaboard for Undergraduate Research and Education (MEASURE), and Mid-continent Magnetoseismic Chain (McMAC). During quiet periods the FLIP model and the observations are in good agreement. During a large storm we find significant differences between the FLIP model and observations. We attribute this difference to the fact that the FLIP model does not automatically incorporate the effects of strong convection, such as a change in flux tube volume (and location), nor the depletion of plasma from the flux tube. In the present study we incorporate these effects realistically and use comparison with observations to estimate their importance in driving the inner plasmasphere during large storms.

Duffy, J.; Jorgensen, A. M.; Zesta, E.; Boudouridis, A.; Chi, P. J.; Moldwin, M.

2011-12-01

82

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

83

Enhancement of seasonal prediction of East Asian summer rainfall related to western tropical Pacific convection  

NASA Astrophysics Data System (ADS)

The prediction skills of climate model simulations in the western tropical Pacific (WTP) and East Asian region are assessed using the retrospective forecasts of seven state-of-the-art coupled models and their multi-model ensemble (MME) for boreal summers (June-August) during the period 1983-2005, along with corresponding observed and reanalyzed data. The prediction of summer rainfall anomalies in East Asia is difficult, while the WTP has a strong correlation between model prediction and observation. We focus on developing a new approach to further enhance the seasonal prediction skill for summer rainfall in East Asia and investigate the influence of convective activity in the WTP on East Asian summer rainfall. By analyzing the characteristics of the WTP convection, two distinct patterns associated with El Niño-Southern Oscillation developing and decaying modes are identified. Based on the multiple linear regression method, the East Asia Rainfall Index (EARI) is developed by using the interannual variability of the normalized Maritime continent-WTP Indices (MPIs), as potentially useful predictors for rainfall prediction over East Asia, obtained from the above two main patterns. For East Asian summer rainfall, the EARI has superior performance to the East Asia summer monsoon index or each MPI. Therefore, the regressed rainfall from EARI also shows a strong relationship with the observed East Asian summer rainfall pattern. In addition, we evaluate the prediction skill of the East Asia reconstructed rainfall obtained by hybrid dynamical-statistical approach using the cross-validated EARI from the individual models and their MME. The results show that the rainfalls reconstructed from simulations capture the general features of observed precipitation in East Asia quite well. This study convincingly demonstrates that rainfall prediction skill is considerably improved by using a hybrid dynamical-statistical approach compared to the dynamical forecast alone.

Lee, Doo Young; Ahn, Joong-Bae; Yoo, Jin-Ho

2014-09-01

84

Diagnosis of the secondary circulation of tropical storm Bilis (2006) and the effects of convective systems on its track  

NASA Astrophysics Data System (ADS)

We diagnose characteristics of the quasi-balanced flow and secondary circulation (SC) of tropical storm Bilis (2006) using the potential vorticity (PV)- ? inversion method. We further analyze how secondary steering flows associated with mesoscale convective systems affected the track of tropical storm Bilis after it made landfall. The quasi-balanced asymmetric and axisymmetric circulation structures of tropical storm Bilis are represented well by the PV- ? inversion. The magnitude of the nonlinear quasi-balanced vertical velocity is approximately 75% of the magnitude simulated using the Weather Research and Forecasting (WRF) model. The SC of Bilis (2006) contained two strong regions of ascending motion, both of which were located in the southwest quadrant of the storm. The first (150-200 km southwest of the storm center) corresponded to the eyewall region, while the second (approximately 400 km southwest of the storm center) corresponded to latent heat release associated with strong precipitation in major spiral rainbands. The SC was very weak in the northeast quadrant (the upshear direction). Dynamical processes related to the environmental vertical wind shear produced an SC that partially offset the destructive effects of the environmental vertical wind shear (by 20%-25%). This SC consisted of upward motion in the southwest quadrant and subsidence in the northeast quadrant, with airflow oriented from southwest to northeast at high altitudes and from northeast to southwest at lower levels. The inverted secondary zonal and meridional steering flows associated with continuous asymmetric mesoscale convective systems were about -2.14 and -0.7 m s-1, respectively. These steering flows contributed substantially to the zonal (66.15%) and meridional (33.98%) motion of the storm at 0000 UTC 15 July 2006. The secondary steering flow had a significant influence on changing the track of Bilis from southward to northward. The direction of the large-scale meridional steering flow (3.02 m s-1) was opposite to the actual meridional motion (-2.06 m s-1).

Yu, Jinhua; Fu, Hao; Tang, Sheng; Sheng, Siwei

2014-02-01

85

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

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

86

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

E-print Network

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

Castro, Christopher L.

87

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

Microsoft Academic Search

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

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

2009-01-01

88

Automatic differentiation as a tool for sensitivity analysis of a convective storm in a 3-D cloud model  

SciTech Connect

The ADIFOR automatic differentiation tool is applied to a 3-D storm-scale meteorological model to generate a sensitivity-enhanced code capable of providing derivatives of all model output variables and related diagnostic (derived) parameters as a function of specified control parameters. The tangent linear approximation, applied to a deep convective storm by the first of its kind using a full-physics compressible model, is valid up to 50 min for a 1% water vapor perturbations. The result is very encouraging considering the highly nonlinear and discontinuous properties of solutions. The ADIFOR-generated code has provided valuable sensitivity information on storm dynamics. Especially, it is very efficient and useful for investigating how a perturbation inserted at earlier time propagates through the model variables at later times. However, it is computationally very expensive to be applied to the variational data assimilation, especially for 3-D meteorological models, which potentially have a large number of input variables.

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

1996-10-01

89

Generated using V3.2 of the official AMS LATEX templatejournal page layout FOR AUTHOR USE ONLY, NOT FOR SUBMISSION! The three-dimensional morphology of simulated and observed convective storms over  

E-print Network

. The modelled storms were surrounded by a region of drizzle without ice reflectivities above 0 dBZ aloft, which, NOT FOR SUBMISSION! The three-dimensional morphology of simulated and observed convective storms over southern Kingdom ABSTRACT A set of high-resolution radar observations of convective storms has been collected

Hogan, Robin

90

Dynamical and Microphysical Retrieval from Doppler Radar Observations Using a Cloud Model and Its Adjoint. Part II: Retrieval Experiments of an Observed Florida Convective Storm  

Microsoft Academic Search

The variational Doppler radar analysis system developed in part I of this study is tested on a Florida airmass storm observed during the Convection and Precipitation\\/ Electrification Experiment. The 3D wind, temperature, and microphysical structure of this storm are obtained by minimizing the difference between the radar-observed radial velocities and rainwater mixing ratios (derived from reflectivity) and their model predictions.

Juanzhen Sun; N. Andrew Crook

1998-01-01

91

The Impacts of Microphysics and Planetary Boundary Layer Physics on Model Simulations of U.S. Deep South Summer Convection  

NASA Technical Reports Server (NTRS)

Convection-allowing numerical weather simula- tions have often been shown to produce convective storms that have significant sensitivity to choices of model physical parameterizations. Among the most important of these sensitivities are those related to cloud microphysics, but planetary boundary layer parameterizations also have a significant impact on the evolution of the convection. Aspects of the simulated convection that display sensitivity to these physics schemes include updraft size and intensity, simulated radar reflectivity, timing and placement of storm initi- ation and decay, total storm rainfall, and other storm features derived from storm structure and hydrometeor fields, such as predicted lightning flash rates. In addition to the basic parameters listed above, the simulated storms may also exhibit sensitivity to im- posed initial conditions, such as the fields of soil temper- ature and moisture, vegetation cover and health, and sea and lake water surface temperatures. Some of these sensitivities may rival those of the basic physics sensi- tivities mentioned earlier. These sensitivities have the potential to disrupt the accuracy of short-term forecast simulations of convective storms, and thereby pose sig- nificant difficulties for weather forecasters. To make a systematic study of the quantitative impacts of each of these sensitivities, a matrix of simulations has been performed using all combinations of eight separate microphysics schemes, three boundary layer schemes, and two sets of initial conditions. The first version of initial conditions consists of the default data from large-scale operational model fields, while the second features specialized higher- resolution soil conditions, vegetation conditions and water surface temperatures derived from datasets created at NASA's Short-term Prediction and Operational Research Tran- sition (SPoRT) Center at the National Space Science and Technology Center (NSSTC) in Huntsville, AL. Simulations as outlined above, each 48 in number, were conducted for five midsummer weakly sheared coastal convective events each at two sites, Mobile, AL (MOB) and Houston, TX (HGX). Of special interest to operational forecasters at MOB and HGX were accuracy of timing and placement of convective storm initiation, reflectivity magnitudes and coverage, rainfall and inferred lightning threat.

McCaul, Eugene W., Jr.; Case, Jonathan L.; Zavodsky, Bradley; Srikishen, Jayanthi; Medlin, Jeffrey; Wood, Lance

2014-01-01

92

Evaluate the urban effect on summer convective precipitation by coupling a urban canopy model with a Regional Climate Model  

NASA Astrophysics Data System (ADS)

One of the most significant urbanization in the world occurred in Great Beijing Area of China during the past several decades. The land use and land cover changes modifies the land surface physical characteristics, including the anthropogenic heat and thermo-dynamic conduction. All of those play important roles in the urban regional climate changes. We developed a single layer urban canopy module based on the Community Land Surface Model Urban Module (CLMU). We have made further improvements in the urban module: the energy balances on the five surface conditions are considered separately: building roof, sun side and shade side wall, pervious and impervious land surface. Over each surface, a method to calculate sky view factor (SVF) is developed based on the physically process while most urban models simply provide an empirical value; A new scheme for calculating the latent heat flux is applied on both wall and impervious land; anthropogenic heat is considered in terms of industrial production, domestic wastes, vehicle and air condition. All of these developments improve the accuracy of surface energy balance processing in urban area. The urban effect on summer convective precipitation under the unstable atmospheric condition in the Great Beijing Area was investigated by simulating a heavy rainfall event in July 21st 2012. In this storm, strong meso-scale convective complexes (MCC) brought precipitation of averagely 164 mm within 6 hours, which is the record of past 60 years in the region. Numerical simulating experiment was set up by coupling MCLMU with WRF. Several condition/blank control cases were also set up. The horizontal resolution in all simulations was 2 km. While all of the control results drastically underestimate the urban precipitation, the result of WRF-MCLMU is much closer to the observation though still underestimated. More sensitive experiments gave a preliminary conclusion of how the urban canopy physics processing affects the local precipitation: the existence of large area of impervious surfaces restrain the surface evaporation and latent heat flux in urban while the anthropogenic heat and enhanced sensible heat flux warm up the lower atmospheric layer and strengthen the vertical stratification instability; In this storm event, the water supply of the MCC was thought to be sufficient, thus the instability of the vertical stratification was the key factor for precipitation.

Liu, Z.; Liu, S.; Xue, Y.; Oleson, K. W.

2013-12-01

93

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

E-print Network

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...

Biwole, Pascal; Pompeo, C

2013-01-01

94

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)

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, ? 18O and ? D 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, Alexander; Strecker, Manfred R.; Bookhagen, Bodo; Mulch, Andreas; Sachse, Dirk; Pingel, Heiko; Alonso, Ricardo N.; Schildgen, Taylor F.; Montero, Carolina

2014-12-01

95

The Storms of SummerLessons Learned in the Aftermath of the Hurricanes of '04  

Microsoft Academic Search

Unlike the hoteliers chronicled in the accompanying report on the blackout of '03, the Walt Disney World® Resort did not face an electrical blackout when three hurricanes passed through Florida during the hurricane season of 2004. However, the dangerous storms forced Walt Disney World to suspend operations and ask guests to remain in their hotel rooms. The storms' violence also

Barbara A. Higgins

2005-01-01

96

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

NASA Technical Reports Server (NTRS)

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.

Zipser, Edward J.; Lutz, Kurt R.

1994-01-01

97

Severe convective storms initiated by intense wildfires: Numerical simulations of pyro-convection and pyro-tornadogenesis  

Microsoft Academic Search

On the afternoon of 18 January 2003, wildfires swept through several outer suburbs of Canberra (Australia) producing, inter alia, a series of large pyro-cumulonimbus cells and at least one tornado. The results of a large-eddy simulation with a parameterized fire are reported here. The simulation, motivated by the Canberra wildfires and severe storms, captures the main characteristics of the observed

Philip Cunningham; Michael J. Reeder

2009-01-01

98

The importance of the representation of deep convection for modeled dust-generating winds over West Africa during summer  

NASA Astrophysics Data System (ADS)

West Africa is the world's largest source of airborne mineral dust. Here, we use continental-scale ten-day convection-permitting simulations from the UK Met Office Unified Model to study the effects of the representation of deep convection on modeled dust-generating winds in summertime West Africa. To isolate the role of meteorology from the land surface we use a new diagnostic parameter "uplift potential", which represents the dependency of dust uplift on wind-speed for an idealized land surface. Runs permitting explicit convection suggest that cold pool outflows from moist convection (so called "haboob" dust storms) potentially generate on the order of half the dust uplift. Simulations with parameterized convection generate significantly less haboob uplift, but show compensating increased uplift from low-level jets associated with a stronger Saharan heat low (SHL). This leads to reduced dust emission on convectively active days, in the afternoon and evening hours, and in the Sahel. The common practice of tuning coarse-resolution dust models cannot resolve these problems. A realistic representation of the dust cycle, as well as of the SHL, requires targeted efforts to develop computationally inexpensive ways to incorporate the effects of cold-pool outflows from deep convection.

Marsham, J.; Knippertz, P.; Dixon, N. S.; Parker, D. J.; Lister, G. M.

2011-12-01

99

Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. 136: 593616, April 2010 Part A Summer monsoon convection in the Himalayan region: Terrain  

E-print Network

2010 Part A Summer monsoon convection in the Himalayan region: Terrain and land cover effects Socorro summer monsoon, convection occurs frequently near the Himalayan foothills. However, the nature-resolution numerical simulations and available observations from two case-studies and of the monsoon climatology

Niyogi, Dev

100

Measurement of Attenuation with Airborne and Ground-Based Radar in Convective Storms Over Land and Its Microphysical Implications  

NASA Technical Reports Server (NTRS)

Observations by the airborne X-band Doppler radar (EDOP) and the NCAR S-band polarimetric (S-POL) radar from two field experiments are used to evaluate the Surface ref'ercnce technique (SRT) for measuring the path integrated attenuation (PIA) and to study attenuation in deep convective storms. The EDOP, flying at an altitude of 20 km, uses a nadir beam and a forward pointing beam. It is found that over land, the surface scattering cross-section is highly variable at nadir incidence but relatively stable at forward incidence. It is concluded that measurement by the forward beam provides a viable technique for measuring PIA using the SRT. Vertical profiles of peak attenuation coefficient are derived in vxo deep convective storms by the dual-wavelength method. Using the measured Doppler velocity, the reflectivities at. the two wavelengths, the differential reflectivity and the estimated attenuation coefficients, it is shown that: supercooled drops and dry ice particles probably co-existed above the melting level in regions of updraft, that water-coated partially melted ice particles probably contributed to high attenuation below the melting level, and that the data are not readil explained in terms of a gamma function raindrop size distribution.

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.; Starr, D. OC. (Technical Monitor)

2001-01-01

101

Measurement of Attenuation with Airborne and Ground-Based Radar in Convective Storms Over Land Its Microphysical Implications  

NASA Technical Reports Server (NTRS)

Observations by the airborne X-band Doppler radar (EDOP) and the NCAR S-band polarimetric (S-Pol) radar from two field experiments are used to evaluate the surface reference technique (SRT) for measuring the path integrated attenuation (PIA) and to study attenuation in deep convective storms. The EDOP, flying at an altitude of 20 km, uses a nadir beam and a forward pointing beam. It is found that over land, the surface scattering cross-section is highly variable at nadir incidence but relatively stable at forward incidence. It is concluded that measurement by the forward beam provides a viable technique for measuring PIA using the SRT. Vertical profiles of peak attenuation coefficient are derived in two deep convective storms by the dual-wavelength method. Using the measured Doppler velocity, the reflectivities at the two wavelengths, the differential reflectivity and the estimated attenuation coefficients, it is shown that: supercooled drops and (dry) ice particles probably co-existed above the melting level in regions of updraft, that water-coated partially melted ice particles probably contributed to high attenuation below the melting level.

Tian, Lin; Heymsfield, G. M.; Srivastava, R. C.; O'C.Starr, D. (Technical Monitor)

2001-01-01

102

A case study of aerosol impacts on summer convective clouds and precipitation over northern China  

NASA Astrophysics Data System (ADS)

The emissions such as greenhouse gases, precursor gases and particulate matters may directly alter the Earth radiative budget or indirectly modify cloud and precipitation processes, and possibly induce changes in climate and the hydrological cycle at the regional to global scale. The previous publications reported a few quantitative assessments and inconsistent results on the effects of the emissions on cloud and precipitation. The aerosol properties and possible impacts on a convective precipitation case on 4 July 2008 over the urban region of northern China are investigated based on the Moderate Resolution Imaging Spectroradiometer (MODIS) data and the Weather Research and Forecast (WRF) model coupled with Chemistry (WRF-Chem). Results show that the Aerosol Optical Depth (AOD) is over 0.9 in the study area, indicating a high concentration of aerosol pollution. The value of Angstrom exponent in the study area is larger than 1.0, indicating that the main particles in the area are industrial and biomass burning pollution aerosols with radii less than 0.25-0.5 ?m. The modeling results show that the domain-averaged precipitation amount under polluted conditions can be increased up to 17% during the whole cloud lifetime. However, the maximum rainfall rate above 30 mm/h is enhanced, whereas that below 30 mm/h is suppressed in most cloud lifetime. The differences of cloud microphysics and dynamics between polluted and clean conditions indicate that both warm and ice microphysics and updraft are suppressed at the storm's initial and dissipating stages, whereas those at the storm's mature stage are obviously enhanced under polluted conditions.

Guo, Xueliang; Fu, Danhong; Guo, Xin; Zhang, Chunming

2014-06-01

103

Mesospheric concentric gravity waves generated by multiple convective storms over the North American Great Plain  

E-print Network

, and had epicenters near the locations of deep convection in three thunderstorms in Colorado, Nebraska the thunderstorms. Using the background wind from a nearby radar, the intrinsic wave parameters and vertical convection (i.e., strong thunderstorms) can frequently excite gravity waves in the lower atmosphere during

Vadas, Sharon

104

Changes in monoterpene mixing ratios during summer storms in rural New Hampshire (USA)  

USGS Publications Warehouse

Monoterpenes are an important class of biogenic hydrocarbons that influence ambient air quality and are a principle source of secondary organic aerosol (SOA). Emitted from vegetation, monoterpenes are a product of photosynthesis and act as a response to a variety of environmental factors. Most parameterizations of monoterpene emissions are based on clear weather models that do not take into account episodic conditions that can drastically change production and release rates into the atmosphere. Here, the monoterpene dataset from the rural Thompson Farm measurement site in Durham, New Hampshire is examined in the context of a set of known severe storm events. While some storm systems had a negligible influence on ambient monoterpene mixing ratios, the average storm event increased mixing ratios by 0.59 ?? 0.21 ppbv, a factor of 93% above pre-storm levels. In some events, mixing ratios reached the 10's of ppbv range and persisted overnight. These mixing ratios correspond to increases in the monoterpene emission rate, ranging from 120 to 1240 g km-2 h -1 compared to an estimated clear weather rate of 116 to 193 g km-2 h-1. Considering the regularity of storm events over most forested areas, this could be an important factor to consider when modeling global monoterpene emissions and their resulting influence on the formation of organic aerosols.

Haase, Karl B.; Jordan, C.; Mentis, E.; Cottrell, L.; Mayne, H. R.; Talbot, R.; Sive, B. C.

2011-01-01

105

Arctic summer storm track in CMIP3/5 climate models  

NASA Astrophysics Data System (ADS)

Model performance and future projection of Arctic summertime storm-track activity and associated background states are assessed on the basis of Coupled Model Intercomparison Project Phase 3 (CMIP3)/5 (CMIP5) climate models. Despite some improvement in the CMIP5 models relative to the CMIP3 models, most of the climate models underestimate summertime storm-track activity over the Arctic Ocean compared to six reanalysis data sets as measured locally as the variance of subweekly fluctuations of sea level pressure. Its large inter-model spread (i.e., model-to-model differences) is correlated with that of the intensity of the Beaufort Sea High and the lower-tropospheric westerlies in the Arctic region. Most of the CMIP3/5 models project the enhancement of storm-track activity over the Arctic Ocean off the eastern Siberian and Alaskan coasts, the region called the Arctic Ocean Cyclone Maximum, in association with the strengthening of the westerlies in the warmed climate. A model with stronger enhancement of the storm-track activity tends to accompany stronger land-sea contrast in surface air temperature across the Siberian coast, which reflects greater surface warming over the continent and slower warming over the Arctic Ocean. Other processes, however, may also be likely to contribute to the future changes of the storm-track activity, which gives uncertainty in the projection by multiple climate models. Our analysis suggests that further clarification of those processes that influence storm-track activity over the Arctic is necessary for more reliable future projections of the Arctic climate.

Nishii, Kazuaki; Nakamura, Hisashi; Orsolini, Yvan J.

2014-07-01

106

The importance of the representation of deep convection for modeled dust-generating winds over West Africa during summer  

NASA Astrophysics Data System (ADS)

West Africa is the world's largest source of airborne mineral dust, which affects weather, climate, and biogeochemical processes. We use continental-scale ten-day simulations from the UK Met Office Unified Model to study the effects of the representation of deep convection on modeled dust-generating winds in summertime West Africa. To isolate the role of meteorology from the land surface we use a new diagnostic parameter “uplift potential”, which represents the dependency of dust uplift on wind-speed for an idealized land surface. Runs permitting explicit convection suggest that cold pool outflows from moist convection (so called “haboob” dust storms) potentially generate on the order of half the dust uplift. Simulations with parameterized convection show substantially less haboob uplift, but compensating increased uplift from low-level jets associated with a stronger Saharan heat low (SHL). This leads to reduced dust emission on convectively active days, in the afternoon and evening hours, and in the Sahel. The common practice of tuning coarse-resolution dust models cannot resolve these problems. A realistic representation of the dust cycle, as well as of the SHL, requires targeted efforts to develop computationally inexpensive ways to incorporate the effects of cold-pool outflows from deep convection.

Marsham, John H.; Knippertz, Peter; Dixon, Nick S.; Parker, Douglas J.; Lister, Grenville M. S.

2011-08-01

107

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

Microsoft Academic Search

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

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

2008-01-01

108

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

109

Observed Relationships among Narrow Bipolar Events, Cloud-to-ground Lightningand Convective Strength in Summer 2005 Great Plains Thunderstorms  

NASA Astrophysics Data System (ADS)

Satellite-based Very High Frequency (VHF) lightning sensors are limited in sensitivity to a particular (but particularly powerful) in-cloud radio frequency (RF) pulse. Hence, the viability of global storm tracking based on satellite-based VHF sensors largely depends on whether these strong in-cloud pulses can be used as robust and generic indicators of convective strength. The RF pulses observed by satellite are sometimes accompanied by distinctive narrow electric field change pulses (called Narrow Bipolar Events or NBEs) observed by ground-based Very Low Frequency sensors such as the Los Alamos Sferic Array (LASA). A recent preliminary study compared LASA NBE flash rates to cloud-to-ground (CG) flash rates in a small geographical area in central and northern Florida. This study used CG flash rates as a proxy for convective strength, and found that NBE flash rates are proportional to CG flash rates, and, by extension, to convective strength. Here, we extend the earlier studies, using an updated LASA in the Great Plains which covers a much larger geographical area and has improved detection efficiency of intra-cloud (IC) flashes. Instead of using CG flash rate as a proxy for convective strength, we use maximum radar reflectivity and maximum height of 30, 40, 50 dBZ radar echo as proxies for convective strength and compare these convective proxies to IC, CG, and NBE flash rates recorded by the Great Plains LASA. In addition to gridded statistical relationships of these quantities, we also present sample case studies to investigate finer-scale temporal and spatial relationships between lightning and convective development.

Wiens, K. C.; Suszcynsky, D. M.

2005-12-01

110

Study on Teleconnection between Winter Convective Activity over Tropical Indian Ocean and Pacific Ocean and Subsequent Summer Precipitation in China Based on Satellite-Derived Data  

Microsoft Academic Search

On the basis of NOAA monthly OLR data and Chinese National Climate Center precipitation data of 160 stations from 1979 to 2007, the spatial and temporal characteristics of winter convection activity over Tropical Indian Ocean and Pacific Ocean (TIOPO) and its relationship with subsequent summer precipitation over China have been analyzed. The results show that the winter convection activity has

Xiaoran Liu; Quanliang Chen; Qian Yang; Bingyan Cheng; Wei Hua

2008-01-01

111

High resolution radiometric measurements of convective storms during the GATE experiment  

NASA Technical Reports Server (NTRS)

Using passive microwave data from the NASA CV-990 aircraft and radar data collected during the Global Atmospheric Research Program Atlantic Tropical Experiment (GATE), an empirical model was developed relating brightness temperatures sensed at 19.35 GHz to surface rainfall rates. This model agreed well with theoretical computations of the relationship between microwave radiation and precipitation in the tropics. The GATE aircraft microwave data was then used to determine the detailed structure of convective systems. The high spatial resolution of the data permitted identification of individual cells which retained unique identities throughout their lifetimes in larger cloud masses and allowed analysis of the effects of cloud merger.

Fowler, G.; Lisa, A. S.

1976-01-01

112

Laboratory and field observations related to ice particle and aircraft charging in convective storms  

NASA Technical Reports Server (NTRS)

Graupel particle charging in simulated cloud conditions which show the need for the presence of ice crystals and cloud water simultaneously except under conditions where secondary ice crystal production occurs when charging initially occurs in the absence of ice crystals was examined. The magnitude of the charging increases with size of ice crystals, and impact velocity; it is also sensitive to impurities. The magnitude of the charge is also sensitive to temperature and the sign changes between -10 and -20 C, depending on cloud liquid water content. Aircraft studies were carried out in Montana convective clouds to test the validity of the extrapolation of the laboratory data to the atmosphere from the viewpoint of generation of charge, electric field, and aircraft charging during cloud penetration.

Christian, H.; Lillie, L.; Saunders, C. P. R.; Hallett, J.

1983-01-01

113

Skywarn Spotter Convective Basics  

NSDL National Science Digital Library

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.

Comet

2011-04-22

114

Ionospheric convection observations following the solar flare of 20 January 2005 and during the geomagnetic storm of 21 January 2005  

NASA Astrophysics Data System (ADS)

The MINIS balloon campaign was successfully conducted in January 2005 to investigate relativistic electron loss mechanisms. The MINIS campaign provided multi-point measurements of electron precipitation up to MeV energies, including simultaneous measurements at different longitudes and hemispheres. Two balloons, each carrying an X-ray spectrometer for measuring the bremsstrahlung produced as electrons precipitate into the atmosphere, were launched from Churchill, Manitoba. Four balloons, each carrying an X-ray spectrometer, and a 3-axis electric field instrument providing DC electric field and VLF measurements in 3 frequency bands, were launched from the South African Antarctic Station (SANAE IV). An X 7.1 solar flare occurred at 0636 UT on 20 January 2005. A CME from this flare arrived at the Earth 34 hours later. An SSC began at ~1650 UT followed by a geomagnetic storm with a Dst perturbation of ~-100nT. The AE index shows that the 20 January flare was followed first by 6 hours of deep quiet and then 28 hours of moderate activity. The balloon data contain evidence for two interesting geoelectric responses to the flare. The response of the tropospheric global circuit is discussed in a companion paper. There was an abrupt reduction of the horizontal electric field to a value near zero. Either the column resistance between the balloon and the ground fell to a value near zero, or the increased load from the ionosphere shorted out the cross-polar-cap potential. The arrival of the CME initiated an interval of very strong relativistic electron precipitation. The second and third Southern payloads and the first Northern payload made observations in both hemispheres of several extensive relativistic electron precipitation events that occurred from 1700 to 2000 UT on 21 January 2005. Each x-ray burst was preceded by a strong pulse of ionospheric convection. These flow bursts were directed poleward and sunward transport. The detailed comparison of data from the two balloons indicates that these bursts were temporal variations, not spatial structures. The data are consistent with an interval of enhanced reconnection and convection preceding each major enhancement in precipitation activity.

Holzworth, R. H.; Bering, E. A.; Reddell, B. D.; Kokorowski, M.; Bale, S.; Blake, J. B.; Collier, A. B.; Hughes, A. R.; Lay, E.; Lin, R. P.; McCarthy, M. P.; Millan, R. M.; Moraal, H.; O'Brien, T. P.; Parks, G. K.; Pulupa, M.; Sample, J. G.; Smith, D. M.; Stoker, P.; Woodger, L.

2005-12-01

115

Analysis of Summer Thunderstorms in Central Alabama Using the NASA Land Information System  

NASA Technical Reports Server (NTRS)

Forecasters have difficulty predicting "random" afternoon thunderstorms during the summer months. Differences in soil characteristics could be a contributing factor for storms. The NASA Land Information System (LIS) may assist forecasters in predicting summer convection by identifying boundaries in land characteristics. This project identified case dates during the summer of 2009 by analyzing synoptic weather maps, radar, and satellite data to look for weak atmospheric forcing and disorganized convective development. Boundaries in land characteristics that may have lead to convective initiation in central Alabama were then identified using LIS.

James, Robert; Case, Jonathan; Molthan, Andrew; Jedloved, Gary

2010-01-01

116

The influence of Nunataks on atmospheric boundary layer convection during summer in Dronning Maud Land, Antarctica  

NASA Astrophysics Data System (ADS)

The effects of nunataks on temperature profiles and wind patterns are studied using simulations from the Weather Research and Forecasting model. Simulations are compared to hourly observations from an automatic weather station located at the Troll Research Station in Dronning Maud Land. Areas of bare ground have been implemented in the model, and the simulations correspond well with meteorological measurements acquired during the 4 day simulation period. The nunataks are radiatively heated during daytime, and free convection occurs in the overlying atmospheric boundary layer. The inflow below the updraft forces strong horizontal convergence at the surface, whereas weaker divergence appears aloft. In a control run with a completely ice-covered surface, the convection is absent. In situ observations carried out by a remotely controlled balloon and a small model airplane compare well with model temperature profiles, but these are only available over the ice field upwind to the nunatak.

Stenmark, Aurora; Hole, Lars Robert; Voss, Paul; Reuder, Joachim; Jonassen, Marius O.

2014-06-01

117

Impact of convection over the equatorial trough on summer monsoon activity over India  

Microsoft Academic Search

Causes of disruption of rainfall (break in monsoon conditions) over the Indian subcontinent during the monsoon months for the period 1979–1998 are investigated using pentad rainfall data from the Global Precipitation Climatology Project (GPCP). Most (about 73%) of the break in monsoon (BM) events were associated with convective activity (rainfall more than 30 mm\\/pentad) over the equatorial trough (ET) region. The

M. R. Ramesh Kumar; S. S. C. Shenoi; J. Schulz

2005-01-01

118

Summer convection and lightning over the Mackenzie river basin and their Impacts during 1994 and 1995  

Microsoft Academic Search

Lightning activity over the Mackenzie basin has been examined for the summers of 1994 and 1995. In recent years, the lightning network operating in the Northwest Territories has detected an average of 118 K strikes per season. Positive lightning strikes (defined as lightning discharges lowering positive charge to the earth) typically comprise 12% of the total. The lightning activity during

B. Kochtubajda; R. E. Stewart; J. R. Gyakum; M. D. Flannigan

2002-01-01

119

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

E-print Network

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

Houze Jr., Robert A.

120

Atmosphere-ocean conditions jointly guide convection of the Boreal Summer Intraseasonal Oscillation: Satellite observations  

Microsoft Academic Search

The water-vapor and air-temperature profiles from the Atmospheric Infrared Sounder (AIRS), in combination with surface wind from Quick Scatterometer (QuikSCAT) and rainfall and sea surface temperature (SST) from Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI), are used to document surface conditions and vertical moist thermodynamic structures of the 2003-2006 Boreal Summer Intraseasonal Oscillation (BSISO) over the Indo-Pacific warm pool.

Bo Yang; Xiouhua Fu; Bin Wang

2008-01-01

121

Atmosphere-ocean conditions jointly guide convection of the Boreal Summer Intraseasonal Oscillation: Satellite observations  

Microsoft Academic Search

The water-vapor and air-temperature profiles from the Atmospheric Infrared Sounder (AIRS), in combination with surface wind from Quick Scatterometer (QuikSCAT) and rainfall and sea surface temperature (SST) from Tropical Rainfall Measurement Mission (TRMM) Microwave Imager (TMI), are used to document surface conditions and vertical moist thermodynamic structures of the 2003–2006 Boreal Summer Intraseasonal Oscillation (BSISO) over the Indo-Pacific warm pool.

Bo Yang; Xiouhua Fu; Bin Wang

2008-01-01

122

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

USGS Publications Warehouse

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.

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

1994-01-01

123

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

NASA Astrophysics Data System (ADS)

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 ice at both ends of the melt season alter all of the terms of the surface energy budget, leading to the onset and end of the summer melt in late May or June and August, respectively. In particular, changes in longwave radiative conditions from clouds located in warm or cold air masses aloft produce key changes to the surface energy budget. This presentation will show these observations and examine the generality of the hypothesis using data from the Russian drifting stations, the North Pole Environmental Observatories, and Arctic Ocean Expedition-2001. The synoptic environment of the freeze-up process will be demonstrated with preliminary data from the recently completed Arctic Mechanisms of Interaction between the Surface and Atmosphere (AMISA) and Arctic Summer Cloud-Ocean Study (ASCOS) field programs.

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

2008-12-01

124

Lightning location relative to storm structure in a leading-line, trailing-stratiform mesoscale convective system  

Microsoft Academic Search

(1) Horizontal and line-normal, vertical cross-sections and composite images of Dallas-Fort Worth Lightning Detection and Ranging (LDAR II) VHF radiation sources and radar reflectivity over a 30-min period provide a unique perspective on lightning pathways within a leading-line, trailing-stratiform (LLTS) mesoscale convective system (MCS) on 16 June 2002. The overwhelming majority of VHF lightning sources occurred within the leading convective

Lawrence D. Carey; Martin J. Murphy; Tracy L. McCormick; Nicholas W. S. Demetriades

2005-01-01

125

Lightning location relative to storm structure in a leading-line, trailing-stratiform mesoscale convective system  

Microsoft Academic Search

Horizontal and line-normal, vertical cross-sections and composite images of Dallas-Fort Worth Lightning Detection and Ranging (LDAR II) VHF radiation sources and radar reflectivity over a 30-min period provide a unique perspective on lightning pathways within a leading-line, trailing-stratiform (LLTS) mesoscale convective system (MCS) on 16 June 2002. The overwhelming majority of VHF lightning sources occurred within the leading convective line

Lawrence D. Carey; Martin J. Murphy; Tracy L. McCormick; Nicholas W. S. Demetriades

2005-01-01

126

Contribution of the MODIS instrument to observations of deep convective storms and stratospheric moisture detection in GOES and MSG imagery  

Microsoft Academic Search

Past studies based on the NOAA\\/AVHRR and GOES I-M imager instruments have documented the link between certain storm top features referred to as the “cold-U\\/V” shape in the 10–12 ?m IR band imagery and plumes of increased 3.7\\/3.9 ?m band reflectivity. Later, similar features in the 3.7\\/3.9 ?m band have been documented in the AVHRR\\/3 1.6 ?m band imagery.The present work focuses on storm

Martin Setvák; Robert M. Rabin; Pao K. Wang

2007-01-01

127

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

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

Xue, Ming

128

Simulations of summer monsoon climate over East Asia with a Regional Climate Model (RegCM) using Tiedtke convective parameterization scheme (CPS)  

NASA Astrophysics Data System (ADS)

In this study, we implemented the Tiedtke convective parameterization scheme (CPS) into the Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model version 3 (RegCM3) and simulated the East Asian Summer Monsoon (EASM) climate. A 6-year experiment was completed, from September 1996 through August 2002, and compared with an analogous experiment employing the Grell CPS option available in RegCM3. The ability of the model to represent the average climatology was investigated. Our results indicate that the Tiedtke CPS shows a generally good performance in describing surface climate and large-scale circulation throughout the summer monsoon period. Compared to the simulation with Grell CPS, the simulation with Tiedtke scheme shows a number of improvements, including a better distribution of summer monsoon precipitation due to a better positioning of the Western Pacific Subtropical High (WPSH) in the middle troposphere and the southwesterly jet in the lower troposphere, and more realistic seasonal evolution of the monsoon precipitation. The cold surface air temperature bias characteristic frequently seen in Grell scheme over this region is also reduced. Generally, the Tiedtke scheme simulates warm and wet atmospheric conditions in the middle and lower tropospheres, a result more in agreement with the European Centre for Medium-Range Weather Forecasts (ECMWF) 40 Years analysis (ERA-40). The Tiedtke scheme is more prone to activate convection in the lower troposphere than the Grell scheme due to more moist static energy available for activating and supporting the development of convection systems.

Bao, Yan

2013-12-01

129

Turbulence structure of the convective boundary layer by means of Doppler lidar measurements  

Microsoft Academic Search

The results of a comparison between lidar and aircraft measurements taken during the Convective Storm Initiation Project CSIP 2005 are presented as well as results from continuous measurements over a two month summer period in 2008 at Forschungszentrum Karlsruhe. The Doppler lidar ''WindTracer\\

K. Arnold; A. Wieser; K. Träumner; N. Kalthoff; U. Corsmeier; R. Hankers; Ch. Kottmeier

2009-01-01

130

Convective Modes for Significant Severe Thunderstorms in the Contiguous United States. Part I: Storm Classification and Climatology  

E-print Network

Convective Modes for Significant Severe Thunderstorms in the Contiguous United States. Part I- ameter), significant wind ($65-kt thunderstorm gusts), and tornadoes were filtered by the maximum event 901 tornado and significant severe thunderstorm events, representing 78.5% of all such reports

131

Intraseasonal Variability of Summer Storms over Central Arizona during 1997 and 1999 PAMELA L. HEINSELMAN* AND DAVID M. SCHULTZ*  

E-print Network

. HEINSELMAN* AND DAVID M. SCHULTZ* Cooperative Institute for Mesoscale Meteorological Studies, University winds, flash flooding, and/or lightning (Sellers and Hill 1974; Hales 1975; Schmidli 1986). Additionally are important to public safety and economics. Arizona's summer wet season occurs in response to the North

Schultz, David

132

Rocket dust storms and detached dust layers in the Martian atmosphere  

NASA Astrophysics Data System (ADS)

Airborne dust is the main climatic agent in the Martian environment. Local dust storms play a key role in the dust cycle; yet their life cycle is poorly known. Here we use mesoscale modeling that includes the transport of radiatively active dust to predict the evolution of a local dust storm monitored by OMEGA on board Mars Express. We show that the evolution of this dust storm is governed by deep convective motions. The supply of convective energy is provided by the absorption of incoming sunlight by dust particles, rather than by latent heating as in moist convection on Earth. We propose to use the terminology "rocket dust storm," or conio-cumulonimbus, to describe those storms in which rapid and efficient vertical transport takes place, injecting dust particles at high altitudes in the Martian troposphere (30-50 km). Combined to horizontal transport by large-scale winds, rocket dust storms produce detached layers of dust reminiscent of those observed with Mars Global Surveyor and Mars Reconnaissance Orbiter. Since nighttime sedimentation is less efficient than daytime convective transport, and the detached dust layers can convect during the daytime, these layers can be stable for several days. The peak activity of rocket dust storms is expected in low-latitude regions at clear seasons (late northern winter to late northern summer), which accounts for the high-altitude tropical dust maxima unveiled by Mars Climate Sounder. Dust-driven deep convection has strong implications for the Martian dust cycle, thermal structure, atmospheric dynamics, cloud microphysics, chemistry, and robotic and human exploration.

Spiga, Aymeric; Faure, Julien; Madeleine, Jean-Baptiste; Määttänen, Anni; Forget, François

2013-04-01

133

Response of mating activity of the plainfin midshipman to inflow into San Francisco Bay from a summer storm  

NASA Astrophysics Data System (ADS)

The plainfin midshipman (Porichthys notatus) is a small fish which nests in estuarine waters during summer months. The male makes a loud continuous droning call to attract females to a nest, where eggs and newborn young are guarded by the male. Midshipman calls have been recorded continuously with a fixed hydrophone near a pier in San Francisco Bay, over two successive mating seasons. A dramatic increase in calling followed a very unusual intense rainstorm in mid-October 2009. This suggests a response to biochemical stimuli from the runoff water. Further study may make it possible to isolate the contaminants producing this alteration of sexual behavior.

Bland, R. W.

2010-12-01

134

Magnetospheric Convection Electric Field Dynamics and Stormtime Particle Energization: Case Study of the Magnetic Storm of May 4,1998  

NASA Technical Reports Server (NTRS)

It is shown that narrow channels of high electric field are an effective mechanism for injecting plasma into the inner magnetosphere. Analytical expressions for the electric field cannot produce these channels of intense plasma flow, and thus result in less entry and energization of the plasma sheet into near-Earth space. For the ions, omission of these channels leads to an underprediction of the strength of the stormtime ring current and therefore an underestimation of the geoeffectiveness of the storm event. For the electrons, omission of these channels leads to the inability to create a seed population of 10-100 keV electrons deep in the inner magnetosphere. These electrons can eventually be accelerated into MeV radiation belt particles.

Khazanov, George V.; Liemohn, Michael W.; Newman, Tim S.; Fok, Mei-Ching; Ridley, Aaron

2003-01-01

135

On the Vertical Structure of Modeled and Observed Deep Convective Storms: Insights for Precipitation Retrieval and Microphysical Parameterization.  

NASA Astrophysics Data System (ADS)

An understanding of the vertical structure of clouds is important for remote sensing of precipitation from space and for the parameterization of cloud microphysics in numerical weather prediction (NWP) models. The representation of cloud hydrometeor profiles in high-resolution NWP models has direct applications in inversion-type precipitation retrieval algorithms [e.g., the Goddard profiling (GPROF) algorithm used for retrieval of precipitation from passive microwave sensors] and in quantitative precipitation forecasting. This study seeks to understand how the vertical structure of hydrometeors (liquid and frozen water droplets in a cloud) produced by high-resolution NWP models with explicit microphysics, henceforth referred to as cloud-resolving models (CRMs), compares to observations. Although direct observations of 3D hydrometeor fields are not available, comparisons of modeled and observed radar echoes can provide some insight into the vertical structure of hydrometeors and, in turn, into the ability of CRMs to produce precipitation structures that are consistent with observations. Significant differences are revealed between the vertical structure of observed and modeled clouds of a severe midlatitude storm over Texas for which the surface precipitation is reasonably well captured. Possible reasons for this discrepancy are presented, and the need for future research is highlighted.

Smedsmo, Jamie L.; Foufoula-Georgiou, Efi; Vuruputur, Venugopal; Kong, Fanyou; Droegemeier, Kelvin

2005-12-01

136

Export mechanisms for dissolved organic carbon and nitrate during summer storm events in a glaciated forested catchment in New York, USA  

NASA Astrophysics Data System (ADS)

Nitrate and dissolved organic carbon (DOC) concentrations during a summer storm for a forested catchment in the Adirondack Mountains displayed a clear separation in trajectories and timing of maximum values. Nitrate concentrations peaked early on the rising limb of the hydrograph, whereas DOC concentrations gradually increased through the rising limb with maximum concentrations following the discharge peak. Solute data from precipitation, throughfall, soilwater, and ground/till water indicated till water and near-surface soil waters as the controlling end members for stream NO3- and DOC concentrations respectively. Streamflow concentrations of major base cations (Ca2+ and Mg2+), which were assumed to represent water originating from deep flow paths, matched the NO3- trajectory. These data suggest that streamflow NO3- concentrations are derived from till groundwater and that DOC is derived from near-surface soil waters. We attributed the early expression of NO3- to the displacement of till waters by infiltrating precipitation. In contrast, we hypothesized that the delayed DOC concentrations occurred with surface and near-surface runoff from near-stream wetlands/peatlands and isolated saturated areas that became connected only under conditions of maximum water content in the catchment.

Inamdar, Shreeram P.; Christopher, Sheila F.; Mitchell, Myron J.

2004-10-01

137

The importance of the representation of deep convection for modeled dust-generating winds over West Africa during summer  

Microsoft Academic Search

New simulations suggest haboobs generate of order half of West African dustGlobal models with parameterized convection greatly underestimate haboob dustHaboobs indirectly impact dust uplift by ventilating the Saharan heat low

John H. Marsham; Peter Knippertz; Nick S. Dixon; Douglas J. Parker; Grenville M. S. Lister

2011-01-01

138

The impact of revised simplified Arakawa-Schubert convection parameterization scheme in CFSv2 on the simulation of the Indian summer monsoon  

NASA Astrophysics Data System (ADS)

Keeping the systematic bias of the climate forecast system model version 2 (CFSv2) in mind, an attempt is made to improve the Indian summer monsoon (ISM) rainfall variability in the model from diurnal through daily to seasonal scale. Experiments with default simplified Arakawa-Schubert (SAS) and a revised SAS schemes are carried out to make 15 years climate run (free run) to evaluate the model fidelity with revised SAS as compared to default SAS. It is clearly seen that the revised SAS is able to reduce some of the biases of CFSv2 with default SAS. Improvement is seen in the annual seasonal cycle, onset and withdrawal but most importantly the rainfall probability distribution function (PDF) has improved significantly. To understand the reason behind the PDF improvement, the diurnal rainfall simulation is analysed and it is found that the PDF of diurnal rainfall has significantly improved with respect to even a high resolution CFSv2 T382 version. In the diurnal run with revised SAS, the PDF of rainfall over central India has remarkably improved. The improvement of diurnal cycle of total rainfall has actually been contributed by the improvement of diurnal cycle of convection and associated convective rainfall. This is reflected in outgoing longwave radiation and high cloud diurnal cycle. This improvement of convective cycle has resolved a long standing problem of dry bias by CFSv2 over Indian land mass and wet bias over equatorial Indian Ocean. Besides the improvement, there are some areas where there are still scopes for further development. The cold tropospheric temperature bias, low cloud fractions need further improvement. To check the role of shallow convection, another free run is made with revised SAS along with shallow convection (SC). The major difference between the new and old SC schemes lies in the heating and cooling behavior in lower-atmospheric layers above the planetary boundary layer. However, the inclusion of revised SC scheme could not show much improvement as compared to revised SAS with deep convection. Thus, it seems that revised SAS with deep convection can be a potentially better parameterization scheme for CFSv2 in simulating ISM rainfall variability.

Ganai, Malay; Mukhopadhyay, P.; Krishna, R. Phani Murali; Mahakur, M.

2014-09-01

139

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.

140

The importance of the representation of deep convection for modeled dust-generating winds over West Africa during summer  

Microsoft Academic Search

West Africa is the world's largest source of airborne mineral dust, which affects weather, climate, and biogeochemical processes. We use continental-scale ten-day simulations from the UK Met Office Unified Model to study the effects of the representation of deep convection on modeled dust-generating winds in summertime West Africa. To isolate the role of meteorology from the land surface we use

John H. Marsham; Peter Knippertz; Nick S. Dixon; Douglas J. Parker; Grenville M. S. Lister

2011-01-01

141

North Polar Dust Storm  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-334, 18 April 2003

This composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle daily global images shows a north polar dust storm on March 7, 2003. Similar late summer storms occurred nearly every day from late February well into April 2003; these were also seen in late summer in 1999 and 2001. The white features at the top of the image are the water ice surfaces of the north polar residual cap. Sunlight illuminates the scene from the lower left.

2003-01-01

142

Urban signatures in the spatial clustering of summer heavy rainfall events over the Beijing metropolitan region  

NASA Astrophysics Data System (ADS)

climatology of summer heavy rainfall events over the Beijing metropolitan region during 2008-2012 is investigated with the aid of an observational network of rain gauges and the Weather Research and Forecasting model. Two "hot spots" of higher frequency of summer heavy rainfall events are observed. One is located over the urban core region and the other resides in the climatological downwind region. Two comparative sets of model runs are designed to assess the effect of land surface properties with and without the presence of the city on the model simulation results. By comparing the two sets of model runs, the changes of rainfall statistics, behaviors of storm cells, and variables related to convection due to urbanization are analyzed and quantified. The intensity of heavy rainfall is increased over the urban and downwind region, corresponding to the locations of the two observed hot spots based on rain gauges. The changes of rainfall statistics suggest that the probability distribution of rainfall is shifted toward a heavier upper tail distribution. The Lagrangian properties of storm cells are examined using a newly developed Storm-Cell Identification procedure. High-echo storm cells tend to split approaching the city and merge in the downwind region. The level of free convection and the height of the planetary boundary layer are significantly increased over the urban region and maximum convective available potential energy is decreased. Increased sensible heat flux from the urban surfaces plays a dominant role in the modification of simulated rainfall from a climatological perspective.

Yang, Long; Tian, Fuqiang; Smith, James A.; Hu, Heping

2014-02-01

143

Moist Convection  

NASA Astrophysics Data System (ADS)

On Jupiter there is little doubt that the water condensation level is the seat of moist convective activity. Two major differences between Earth and Jupiter are the importance of the relatively high molecular weight of water on Jupiter and the altered bottom boundary condition on Jupiter. In addition, the triggering mechanism for convection by large scale motion is not yet understood. On Saturn the Great Storm came at a good time for Cassini observations, and the most interesting is the reversal in direction of the vertical motion tracers parahydrogen and potential temperature. Uranus and Neptune appear, on the basis of much less information, to be more exotic. With a high degree of uncertainty we here conjecture that moist convection on these planets is affected by hydrogen ortho-para latent heat in addition to water and methane and that intermittency is the outcome in both the spatial and temporal domains.

Gierasch, Peter J.

2014-11-01

144

Deep convection observed by the Spinning Enhanced Visible and Infrared Imager on board Meteosat 8: Spatial distribution and temporal evolution over Africa in summer and winter 2006  

Microsoft Academic Search

We analyze the spatial distribution of deep convection and its diurnal cycle and life cycle over Africa in June and December 2006. We investigate regions of distinct temporal evolution and of largest frequency of occurrence of deep convection (hereinafter referred to as convective activity), and we define and identify the deep convective stage from space observations. The analysis is based

Marc Schröder; Marianne König; Johannes Schmetz

2009-01-01

145

Climatology of summer midtropospheric perturbations in the U.S. northern plains. Part I: Influence on northwest flow severe weather outbreaks  

SciTech Connect

Northwest flow severe weather outbreaks (NWF outbreaks) describe a type of summer convective storm that occurs in areas of mid-level NWF in the central United States. Convective storms associated with NWF outbreaks are often progressive (i.e. traveling a long distance) along systematic, northwestsoutheast oriented tracks throughout the northern plains. Previous studies have observed that progressive convective storms under NWF are often coupled with subsynoptic-scale midtropospheric perturbations (MPs) coming from the Rocky Mountains. This study traces such MPs for the decade of 1997-2006 using the North American Regional Reanalysis to examine their climatology and possible influence on NWF outbreaks. MPs initiated over the Rocky Mountains have a maximum frequency in July when the North American anticyclone fully develops and forms prevailing NWF over the northern plains. MPs developed under this anticyclone appear restricted in their vertical extension. Nevertheless, persistent upward motion is apparent in the leading edge (east) of MPs soon after their genesis subsequently inducing or intensifying convective storms. MPs propagate along systematic tracks similar to those of NWF outbreaks. The propagation of MPs also synchronizes with the progressive behavior of the associated convective storms. When encountering strong low-level jets (LLJs), upward motion and convergence of water vapor flux associated with MPs intensify substantially, resulting in strongly enhanced convection and precipitation. Convective wind and hail frequencies associated with MPs in strong LLJs reveal a pattern and magnitude very similar to that of NWF outbreaks. While about 60% of summer rainfall in the northern plains is linked to MPs, 75% of these instances occur in strong LLJs.

Wang, Shih-Yu; Chen, Tsing-Chang; Correia, James

2011-02-13

146

Winter Storms  

NSDL National Science Digital Library

This site offers general background about winter storms as well as interactive activities to teach visitors about these storms. It also offers a teacher's 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.

1996-01-01

147

Rainfall Climatology of the US Based on a Multifractal Storm Model  

NASA Astrophysics Data System (ADS)

Whether the multifractal properties of rainfall are impacted by climatology and therefore deviate from universality is a vexing question in both hydrology and the climate sciences and a crucial issue for rainfall downscaling applications. In a recent paper, Veneziano and Lepore (The Scaling of Temporal Rainfall, WRR, 2012) suggested a rainfall model with alternating storms and dry inter-storm periods and beta-lognormal multifractal rainfall intensity inside the storms. The parameters of the model are the rate of storm arrivals ? , the mean value mD and coefficient of variation VD of storm duration, the mean rainfall intensity inside the storms mI, and the multifractal parameters C? (lacunarity), CLN (intermittency), and dmax (outer limit of the scaling range). We use this model and 200 hourly rainfall records from NOAA to describe the variability of intense rainfall over the continental US. The records are selected based on length (at least 25 years) and data quality (quantization, fraction of unavailable values, periods when rainfall is reported as aggregated total depth…). We conclude that CLN and dmax display large systematic variations in space and with season. In particular, CLN decreases as latitude increases, from 0.20-0.25 along the Gulf of Mexico to about 0.12 in New England and 0.08 in the Northwest. This spatial variation is captured in approximation by partitioning the continental US into 11 climatic regions. Seasonal analysis shows that in most regions CLN is highest in the summer and lowest in the winter, following similar variations in the frequency and intensity of convective rainfall. An exception is the Northwest region, where CLN is almost constant throughout the year. The outer scale dmax is negatively correlated with CLN and follows opposite trends. The lacunarity parameter C? is lowest (around 0.04) in the Northeast and highest (around 0.07) in Florida and the Midwestern region. Lacunarity tends to be higher in the spring and summer. Analysis in time using consecutive 10-yr windows and data aggregation by climatic region shows virtually no trend and fluctuations that are far smaller than the seasonal and regional effects. We also study the spatial and temporal variation of the non-multifractal parameters ? , mD, VD, and mI. Finally, we investigate the relationships between the multifractal parameters and (a) indices of atmospheric convection like the convective available potential energy and the frequency of thunderstorms and (b) simple statistical properties of positive hourly rainfall like the coefficient of variation and the probability of exceeding thresholds that are often used to differentiate between convective and frontal regimes or shallow and deep convection. Statistics of the "b" type have the highest positive correlation with CLN.

Lepore, C.; Molini, A.; Veneziano, D.; Yoon, S.

2012-12-01

148

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)

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.

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

149

Taming tornadoes: storm abatement from space  

Microsoft Academic Search

Tornadoes represent the most dangerous and destructive of storms. This paper describes a concept for disrupting the formation of tornadoes in a thunderstorm. Beamed microwave energy from a satellite heats cold rain to affect convective forces in the storm cell. This paper describes a Thunderstorm Solar Power Satellite (TSPS). The TSPS is based on Space Solar Power Program (SSP) concepts

Bernard J. Eastlund; Lyle M. Jenkins

2001-01-01

150

Taming Tornadoes Storm Abatement from Space  

Microsoft Academic Search

Tornadoes represent the most dangerous and destructive of storms. This paper describes a concept for disrupting the formation of tornadoes in a thunderstorm. Beamed microwave energy from a satellite heats cold rain to affect convective forces in the storm cell. This describes a Thunderstorm Solar Power Satellite (TSPS). The TSPS is based on Space Solar Power Program (SSP) concepts and

Bernard J. Eastlund; Lyle M. Jenkins

2007-01-01

151

Remote sensing of tornadic storms from space  

NASA Technical Reports Server (NTRS)

By using infrared images obtained from GOES satellite, the digital count values of pixels representing blackbody temperatures of the cloud top, convective storms are observed throughout their life cycles. Clouds associated with a tornadic storm are compared with those without a tornadic storm to illustrate how the infrared and visible observations from a geosynchronous satellite can be used to study the differences in their life cycles.

Hung, R. J.; Smith, R. E.

1982-01-01

152

Retrieval and use of high-resolution moisture and stability fields from Nimbus 6 HIRS radiances in pre-convective situations. [for severe storm forecasting  

NASA Technical Reports Server (NTRS)

A moisture-temperature retrieval scheme was developed for lower-tropospheric analysis and forecasting parameters from the Nimbus 6 High-resolution Infrared Radiation Sounder, in a study of convective development on the Great Plains of the U.S. on four case study days in August 1975. Dew points and temperatures, along with such secondary parameters as total precipitate water and static stability indices, were derived and analyzed at a horizontal resolution of up to 30 km on the four days. Convective development beginning 2.0-2.5 hours after the satellite pass at local noon was found to correlate well with local moisture and instability maxima seen in the satellite-derived analyses. A statistical structure analysis of the satellite-derived parameters gave the highest signal-to-noise values for the moisture and stability parameters, while the temperature parameters showed much lower signal-to-noise content.

Hillger, D. W.; Vonder Haar, T. H.

1981-01-01

153

Daytime identification of summer hailstorm cells from MSG data  

NASA Astrophysics Data System (ADS)

Identifying deep convection is of paramount importance, as it may be associated with extreme weather phenomena that have significant impact on the environment, property and populations. A new method, the hail detection tool (HDT), is described for identifying hail-bearing storms using multispectral Meteosat Second Generation (MSG) data. HDT was conceived as a two-phase method, in which the first step is the convective mask (CM) algorithm devised for detection of deep convection, and the second a hail mask algorithm (HM) for the identification of hail-bearing clouds among cumulonimbus systems detected by CM. Both CM and HM are based on logistic regression models trained with multispectral MSG data sets comprised of summer convective events in the middle Ebro Valley (Spain) between 2006 and 2010, and detected by the RGB (red-green-blue) visualization technique (CM) or C-band weather radar system of the University of León. By means of the logistic regression approach, the probability of identifying a cumulonimbus event with CM or a hail event with HM are computed by exploiting a proper selection of MSG wavelengths or their combination. A number of cloud physical properties (liquid water path, optical thickness and effective cloud drop radius) were used to physically interpret results of statistical models from a meteorological perspective, using a method based on these "ingredients". Finally, the HDT was applied to a new validation sample consisting of events during summer 2011. The overall probability of detection was 76.9 % and the false alarm ratio 16.7 %.

Merino, A.; López, L.; Sánchez, J. L.; García-Ortega, E.; Cattani, E.; Levizzani, V.

2014-04-01

154

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

155

Doswell, C. A. III, and D. M. Schultz, 2006: On the use of indices and parameters in forecasting severe storms. Electronic J. Severe Storms Meteor., 1, 114.  

E-print Network

severe storms. Electronic J. Severe Storms Meteor., 1, 1­14. 1 On the Use of Indices and Parameters refer to diagnostic variables, such as convective available potential energy (CAPE) or the super- cell

Schultz, David

156

Magnetic Storms  

NASA Technical Reports Server (NTRS)

This talk provides a brief summary of the first conference devoted entirely to magnetic storms. Topics cover the relevant phenomena at the Sun/corona, propogation of these structures through interplanetary space, the response of the magnetosphere to interaction with these interplanetary structures, the formation of the storm time ring current (in particular the oxygen content of the ring-current), and storm ionospheric effects and ground based effects.

Tsurutani, B. T.; Gonzalez, W. D.; Kamide, Y.

1996-01-01

157

Magnetic Storms  

Microsoft Academic Search

IN his article upon the recent magnetic storm (NATURE, September 30) Dr. Chree writes:- ``Another difficulty in regarding the phenomena of magnetic storms as entirely and directly due to the action of electrical currents associated with aurora is that it is a frequent occurrence-as on the present occasion-for the horizontal force to be considerably depressed below the normal value when

W. van Bemmelen

1909-01-01

158

Hail Storms  

NSDL National Science Digital Library

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.

Moore, Gene

159

Gravity wave initiated convection  

NASA Technical Reports Server (NTRS)

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.

Hung, R. J.

1990-01-01

160

3Dimensional simulations of storm dynamics on Saturn  

Microsoft Academic Search

The formation and evolution of convective clouds in the atmosphere of Saturn is investigated using an anelastic three-dimensional time-dependent model with parameterized microphysics. The model is designed to study the development of moist convection on any of the four giant planets and has been previously used to investigate the formation of water convective storms in the jovian atmosphere. The role

R. Hueso; A. Sanchez-Lavega

2000-01-01

161

On the generation/decay of the storm-enhanced density plumes: Role of the convection flow and field-aligned ion flow  

NASA Astrophysics Data System (ADS)

density (SED) plumes are prominent ionospheric electron density increases at the dayside middle and high latitudes. The generation and decay mechanisms of the plumes are still not clear. We present observations of SED plumes during six storms between 2010 and 2013 and comprehensively analyze the associated ionospheric parameters within the plumes, including vertical ion flow, field-aligned ion flow and flux, plasma temperature, and field-aligned currents, obtained from multiple instruments, including GPS total electron content (TEC), Poker Flat Incoherent Scatter Radar (PFISR), Super Dual Auroral Radar Network, and Active Magnetosphere and Planetary Electrodynamics Response Experiment. The TEC increase within the SED plumes at the PFISR site can be 1.4-5.5 times their quiet time value. The plumes are usually associated with northwestward E × B flows ranging from a couple of hundred m s-1 to > 1 km s-1. Upward vertical flows due to the projection of these E × B drifts are mainly responsible for lifting the plasma in sunlit regions to higher altitude and thus leading to plume density enhancement. The upward vertical flows near the poleward part of the plumes are more persistent, while those near the equatorward part are more patchy. In addition, the plumes can be collocated with either upward or downward field-aligned currents (FACs) but are usually observed equatorward of the peak of the Region 1 upward FAC, suggesting that the northwestward flows collocated with plumes can be either subauroral or auroral flows. Furthermore, during the decay phase of the plume, large downward ion flows, as large as ~200 m s-1, and downward fluxes, as large as 1014 m-2 s-1, are often observed within the plumes. In our study of six storms, enhanced ambipolar diffusion due to an elevated pressure gradient is able to explain two of the four large downward flow/flux cases, but this mechanism is not sufficient for the other two cases where the flows are of larger magnitude. For the latter two cases, enhanced poleward thermospheric wind is suggested to be another mechanism for pushing the plasma downward along the field line. These downward flows should be an important mechanism for the decay of the SED plumes.

Zou, Shasha; Moldwin, Mark B.; Ridley, Aaron J.; Nicolls, Michael J.; Coster, Anthea J.; Thomas, Evan G.; Ruohoniemi, J. Michael

2014-10-01

162

Regional scale flood modeling using NEXRAD rainfall, GIS, and HEC-HMS/RAS: a case study for the San Antonio River Basin Summer 2002 storm event.  

PubMed

This paper develops a framework for regional scale flood modeling that integrates NEXRAD Level III rainfall, GIS, and a hydrological model (HEC-HMS/RAS). The San Antonio River Basin (about 4000 square miles, 10,000 km2) in Central Texas, USA, is the domain of the study because it is a region subject to frequent occurrences of severe flash flooding. A major flood in the summer of 2002 is chosen as a case to examine the modeling framework. The model consists of a rainfall-runoff model (HEC-HMS) that converts precipitation excess to overland flow and channel runoff, as well as a hydraulic model (HEC-RAS) that models unsteady state flow through the river channel network based on the HEC-HMS-derived hydrographs. HEC-HMS is run on a 4 x 4 km grid in the domain, a resolution consistent with the resolution of NEXRAD rainfall taken from the local river authority. Watershed parameters are calibrated manually to produce a good simulation of discharge at 12 subbasins. With the calibrated discharge, HEC-RAS is capable of producing floodplain polygons that are comparable to the satellite imagery. The modeling framework presented in this study incorporates a portion of the recently developed GIS tool named Map to Map that has been created on a local scale and extends it to a regional scale. The results of this research will benefit future modeling efforts by providing a tool for hydrological forecasts of flooding on a regional scale. While designed for the San Antonio River Basin, this regional scale model may be used as a prototype for model applications in other areas of the country. PMID:15854726

Knebl, M R; Yang, Z-L; Hutchison, K; Maidment, D R

2005-06-01

163

Magnetic Storms  

NASA Technical Reports Server (NTRS)

One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine. A few years later, speculation on a causal relationship between flares and storms arose when Carrington reported that a large magnetic storm followed the great September 1859 solar flare. However, it was not until this century that a well-accepted statistical survey on large solar flares and geomagnetic storms was performed, and a significant correlation between flares and geomagnetic storms was noted. Although the two phenomena, one on the Sun and the other on the Earth, were statistically correlated, the exact physical linkage was still an unknown at this time. Various hypotheses were proposed, but it was not until interplanetary spacecraft measurements were available that a high-speed plasma stream rich in helium was associated with an intense solar flare. The velocity of the solar wind increased just prior to and during the helium passage, identifying the solar ejecta for the first time. Space plasma measurements and Skylab's coronagraph images of coronal mass elections (CMES) from the Sun firmly established the plasma link between the Sun and the Earth. One phenomenon associated with magnetic storms is brilliant "blood" red auroras, as shown.

Tsurutani, Bruce T.; Gonzalez, Walter D.

1998-01-01

164

Monitoring and Understanding Trends in Extreme Storms: State of Knowledge  

E-print Network

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 ...

Kunkel, Kenneth E.

165

Doswell, C. A. III, and D. M. Schultz, 2006: On the use of indices and parameters in forecasting severe storms. Electronic J. Severe Storms Meteor., 1(3), 122.  

E-print Network

severe storms. Electronic J. Severe Storms Meteor., 1(3), 1­22. 1 On the Use of Indices and Parameters refer to diagnostic variables, such as convective available potential energy (CAPE) or the super- cell

Doswell III, Charles A.

166

Tropical Storm Erin  

NASA Technical Reports Server (NTRS)

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.

2007-01-01

167

Magnetic storms  

Microsoft Academic Search

Solar chromospheric outbursts propagate various disturbances to the ; earth. Among these influences are electromagnetic wave s, high-energy particles, ; shock wave s, and the solar wind. The roles played by each of these factors in ; the production and behavior of geomagnetic storms are considered. Attention is ; devoted to the solar explosions themselves, the propagation of the disturbances

T. Gold

1962-01-01

168

Severe storms  

NASA Technical Reports Server (NTRS)

An overview of severe storms given by a representative of the U.S. Department of Commerce/NOAA and how they affect aviation is presented. What is being done and the organizations responsible for the work in this area are briefly discussed. A partial list of the things that the representative feels need to be done is also presented.

Connolly, J. W.

1978-01-01

169

Day-time identification of summer hailstorm cells from MSG data  

NASA Astrophysics Data System (ADS)

Identifying deep convection is of paramount importance, as it may be associated with extreme weather that has significant impact on the environment, property and the population. A new method, the Hail Detection Tool (HDT), is described for identifying hail-bearing storms using multi-spectral Meteosat Second Generation (MSG) data. HDT was conceived as a two-phase method, in which the first step is the Convective Mask (CM) algorithm devised for detection of deep convection, and the second a Hail Detection algorithm (HD) for the identification of hail-bearing clouds among cumulonimbus systems detected by CM. Both CM and HD are based on logistic regression models trained with multi-spectral MSG data-sets comprised of summer convective events in the middle Ebro Valley between 2006-2010, and detected by the RGB visualization technique (CM) or C-band weather radar system of the University of León. By means of the logistic regression approach, the probability of identifying a cumulonimbus event with CM or a hail event with HD are computed by exploiting a proper selection of MSG wavelengths or their combination. A number of cloud physical properties (liquid water path, optical thickness and effective cloud drop radius) were used to physically interpret results of statistical models from a meteorological perspective, using a method based on these "ingredients." Finally, the HDT was applied to a new validation sample consisting of events during summer 2011. The overall Probability of Detection (POD) was 76.9% and False Alarm Ratio 16.7%.

Merino, A.; López, L.; Sánchez, J. L.; García-Ortega, E.; Cattani, E.; Levizzani, V.

2013-10-01

170

Storm morphology and electrification from CHUVA-GLM Vale do Paraiba field campaign  

NASA Astrophysics Data System (ADS)

CHUVA [Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement)] Project is a series of itinerant field campaigns with the objective of characterizing the main precipitating systems observed in Brazil as a support for Global Precipitation Measurement (GPM) mission. The fourth field campaign was conducted at Vale do Paraiba in São Paulo, Brazil, from 1 November 2011 to 31 March 2012. For this specific field experiment, several lightning location systems (LLS) were deployed as part of GOES-R Geostationary Lightning Mapper (GLM) and MTG Lightning Imager (LI) pre-launch activities, resulting in a joint effort between INPE, USP, NOAA, NASA, EUMETSAT and several vendors of operational LLS for network intercomparison and GLM and LI proxy data generation. Among these networks, 4 of them detect total (intra-cloud and cloud-to-ground) lightning, including a Lightning Mapping Array (LMA), allowing a detailed description of the cloud electrification. To depict precipitating weather systems, CHUVA uses a mobile XPOL Doppler Radar, micro-rain radars, disdrometers, rain gauges, microwave radiometer, Lidar, and a GPS network for water vapor retrievals. Also, Vale do Paraíba and São Paulo are covered by 3 operational S-band radars. The precipitation data collected by these radars and the lightning detected by the LLS were grouped in a structure of storm features built by tracking the precipitating systems and its associated lightning. This storm feature database makes it easier to group similar convective systems and compare them in terms of area, lifetime, rainfall and convection intensity, lightning activity, and more. During this field experiment a large variety of cloud systems were sampled: cold fronts, squall lines, the South Atlantic Convergence Zone (SACZ) and local convective systems. Microphysical characteristics (such as hydrometeor identification and ice/water mass) of these summer 2011-2012 precipitating systems can be inferred from the X-Pol and 3 operational S-band radars, and the LLS provide detailed information about the storms electrical activity (such as charge centers and lighting propagation processes). We will summarize the results from this experiment providing an in-depth study of the relationship between the storm type and its microphysical-electrical characteristics by presenting the role of storm morphology on cloud electrification, rainfall and severe weather (hail and damaging winds) production. Also, this storm feature database will provide an easy access to CHUVA data for case studies and GLM and LI activities.

Albrecht, R. I.; Morales, C.; Lima, W. F.; Biscaro, T. S.; Mello, I. B.

2013-12-01

171

Principles of Convection II: Using Hodographs  

NSDL National Science Digital Library

This module provides a basic understanding of how to plot and interpret hodographs, with application to convective environments. Most of the material previously appeared in the CD module, Anticipating Convective Storm Structure and Evolution, developed with Dr. Morris Weisman. Principles of Convection II: Using Hodographs 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.

Comet

2003-10-28

172

Rocket dust storms and detached dust layers in the Martian atmosphere  

E-print Network

Rocket dust storms and detached dust layers in the Martian atmosphere Aymeric Spiga,1 Julien Faure heating as in moist convection on Earth. We propose to use the terminology "rocket dust storm," or conio-scale winds, rocket dust storms produce detached layers of dust reminiscent of those observed with Mars Global

Spiga, Aymeric

173

TRMM precipitation bias in extreme storms in South America Kristen L. Rasmussen,1  

E-print Network

, indicating that storms with significant mixed phase and ice hydrometeors are similarly affectedTRMM precipitation bias in extreme storms in South America Kristen L. Rasmussen,1 Stella L. Choi,1 June 2013; published 9 July 2013. [1] Deep convective storms in subtropical South America are some

Houze Jr., Robert A.

174

Spectrum of infrasound radiation from supercell storms  

Microsoft Academic Search

We consider the generation of acoustic waves by turbulent convection and perform spectral analysis of a monopole source of sound related to the heat production by condensation of moisture. A quantitative explanation of the correlation between intensity of infrasound generated by supercell storms and later tornado formation is given. It is shown that low lifting condensation level (LCL) and high

M. Akhalkatsi; G. Gogoberidze

2011-01-01

175

Summer Monsoon, Kalahari Desert, Africa  

NASA Technical Reports Server (NTRS)

The Kalahari Desert in southern Africa (28.0S, 26.0E) had not experienced significant rainfall for several months until the onset of the summer monsoon as illustrated by the several large thunderheads peaking above the storm clouds. The summer monsoon, with its associated thunderstorms, generally lasts from November through March and contributes almost all of the annual rainfall to this environmentally sensitive region.

1992-01-01

176

Does Ice Matter? Heavy Rainfall from Warm and Mixed-phase Convection in COPE  

NASA Astrophysics Data System (ADS)

The COnvective Precipitation E experiment (COPE), which took place over the southwestern peninsula of the UK in Summer 2013, was motivated by a number of convective storms that produced flash flooding, chief among them the Boscastle flood event of 2004. Cloud tops during the Boscastle flood reached temperatures of -15 to -20 °C. Coupled with possible seeding from aloft, it was reasonable to presume that ice processes played an important role in precipitation formation. Some heavy precipitation events were sampled by the suite of ground-based and airborne instruments assembled for COPE, despite the unusually warm and dry weather in the UK at that time. Convective cells during several of these events had tops below the freezing level, or not far above where no ice was observed by the aircraft. Impressively, heavy rainfall was observed at the ground-based X-band radar with reflectivities frequently exceedeeding +60 dBZ. Here we use new in situ observations from the University of Wyoming King Air and the Wyoming Cloud Radar to corroborate reflectivity from the ground-based X-band radar. These observations, along with atmospheric soundings and calculations from a 1D warm rain model, are also utilized to understand the dynamic, thermodynamic and microphysical structure of these heavily precipitating convective cells. These observations lead us to question the prevalent assumption that ice processes are critical to the production of heavy convective precipitation.

Leon, David.; Lasher-Trapp, Sonia; French, Jeffrey; Blyth, Alan; Bennett, Lindsay; Brown, Phil

2014-05-01

177

Magnetic Storms As Seen By Image  

NASA Astrophysics Data System (ADS)

Since its launch in March 2000, the NASA IMAGE spacecraft has observed a large variety of magnetic storms ranging from small events up to several "superstorms". Using energetic neutral atoms (ENAs) as tracers for the charged particle dynamics, the Medium and High Energy Neutral Atom Imagers (MENA and HENA, respec- tively) imaged these storms covering the whole inner magnetosphere simultaneously. Depending on the energy range, MENA and HENA measurements give insight into dynamics controlled by a varying combination of corotation, convection and magnetic drifts. We are presenting IMAGE ENA observations illustrating the storm time ring current configuration, effects of substorm injections during storms, and first results on the composition of ENA measurements during storms. Time periods will include the events of 4-6 October 2000, 12 August 2000 and 31 March 2001. The storm time ring current exhibits a stronger dependence on interplanetary magnetic field (IMF) conditions than on storm phase. In particular, the ring current is distinctly asymmet- ric for southward IMF conditions even in the recovery phase, whereas it can become symmetric already during the main phase if the IMF turns northward. Examples of the role of substorms during geomagnetic storms include the 4-6 October 2000 storm, where a series of "sawtooth injections" during moderately southward IMF conditions shows repeated injection of fresh plasma sheet material into what appears to be a par- tial, or untrapped, ring current. In connection with the storm-substorm relationship we will also present first results on ENA composition measurements, showing bursts of oxygen ENA's associated with substorm injections during storms.

Jahn, J.-M.; Brandt, P. C.; Demajistre, R.; Henderson, M. G.; McComas, D. J.; Mitchell, D. G.; Perez, J. D.; Pollock, C. J.; Reeves, G. D.; Roelof, E. C.; Skoug, R.; Thomsen, M. F.

178

Methane Storms and Rain on Titan's Atmosphere from Numerical Simulations  

NASA Astrophysics Data System (ADS)

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 and Cassini radar images have shown a terrain shaped by erosion of probably liquid origin, suggestive of past rain. On the other hand, Voyager IRIS spectroscopic observations of Titan indicate that methane saturation occurs amounting perhaps to 150%, suggesting that the satellite should regularly be covered by methane clouds. Telescopic observations from the Earth and Cassini have shown that clouds are localized, transient and fast evolving, in particular in the South Polar Region (currently in its summer season until its autumn equinox in 2008). To explain these observations, we investigate different scenarios of moist convective storms on Titan using a three-dimensional cloud resolving model that incorporates microphysics and allows computing the precipitation that reaches the surface as a function of the concentration of cloud condensation nuclei in the atmosphere. We show that under the appropriate conditions, precipitation rates comparable to intense tropical storms on Earth could take place. A typical storm may form when the methane humidity is on the order of 80%, developing vertical velocities of 20 ms-1 with the updrafts reaching up to 30 km height during a total life-span of a few hours, producing maximum precipitation rates of 100 kgm-2, that are comparable to flash-floods on Earth. Acknowledgements: This work has been funded by Spanish MCYT PNAYA2003-03216, fondos FEDER and Grupos UPV 15946/2004. R. Hueso acknowledges an RyC research contract form the Spanish MEC.

Hueso, Ricardo; Sánchez-Lavega, A.

2006-09-01

179

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...

180

Storm diagnostic/predictive images derived from a combination of lightning and satellite imagery  

NASA Technical Reports Server (NTRS)

A technique is presented for generating trend or convective tendency images using a combination of GOES satellite imagery and cloud-to-ground lightning observations. The convective tendency images can be used for short term forecasting of storm development. A conceptual model of cloud electrical development and an example of the methodology used to generate lightning/satellite convective tendency imagery are given. Successive convective tendency images can be looped or animated to show the previous growth or decay of thunderstorms and their associated lighting activity. It is suggested that the convective tendency image may also be used to indicate potential microburst producing storms.

Goodman, Steven J.; Buechler, Dennis E.; Meyer, Paul J.

1988-01-01

181

Current understanding of magnetic storms: Storm-substorm relationships  

SciTech Connect

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 primary causes of enhanced electric fields in the interplanetary medium responsible for geomagnetic storms. It is pointed out that in reality, these four mechanisms, which are not mutually exclusive, but interdependent, interact differently from event to event. Interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs) are found to be the primary phenomena responsible for the main phase of geomagnetic storms. The other two mechanisms, i.e., HILDCAA (high-intensity, long-duration, continuous auroral electrojet activity) and the so-called Russell-McPherron effect, work to make the ICME and CIR phenomena more geoeffective. The solar cycle dependence of the various sources in creating magnetic storms has yet to be quantitatively understood. (2) A serious controversy exists as to whether the successive occurrence of intense substorms plays a direct role in the energization of ring current particles or whether the enhanced electric field associated with southward IMF enhances the effect of substorm expansions. While most of the {ital Dst} variance during magnetic storms can be solely reproduced by changes in the large-scale electric field in the solar wind and the residuals are uncorrelated with substorms, recent satellite observations of the ring current constituents during the main phase of magnetic storms show the importance of ionospheric ions. This implies that ionospheric ions, which are associated with the frequent occurrence of intense substorms, are accelerated upward along magnetic field lines, contributing to the energy density of the storm-time ring current. An apparently new controversy regarding the relative importance of the two processes is thus created. It is important to identify the role of substorm occurrence in the large-scale enhancement of magnetospheric convection driven by solar wind electric fields. (3) Numerical schemes for predicting geomagnetic activity indices on the basis of solar/solar wind/interplanetary magnetic field parameters continue to be upgraded, ensuring reliable techniques for forecasting magnetic storms under real-time conditions. There is a need to evaluate the prediction capability of geomagnetic indices on the basis of physical processes that occur during storm time substorms. (4) It is crucial to differentiate between storms and nonstorm time substorms in terms of energy transfer/conversion processes, i.e., mechanical energy from the solar wind, electromagnetic energy in the magnetotail, and again, mechanical energy of particles in the plasma sheet, ring current, and aurora. To help answer the question of the role of substorms in energizing ring current particles, it is crucial to find efficient magnetospheric processes that heat ions up to some minimal energies so that they can have an effect on the strength of the storm time ring current. (5) The question of whether the {ital Dst} index is an accurate and effective measure of the storm time ring-current is also controversial. In particular, it is demonstrated that the dipolarization effect associated with substorm expansion acts to reduce the {ital Dst} magnitude, even though the ring current may still be growing. {copyright} 1998 American Geophysical Union

Kamide, Y.; Gonzalez, W.D. [Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa (Japan)] [Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa (Japan); Baumjohann, W. [Max-Planck-Institut fuer extraterrestrische Physik, Garching (Germany)] [Max-Planck-Institut fuer extraterrestrische Physik, Garching (Germany); Daglis, I.A. [Institute of Ionospheric and Space Research, National Observatory of Athens, Penteli, (Greece)] [Institute of Geophysics and Planetary Physics, University of California, Los Angeles (United States)] [Institute of Ionospheric and Space Research, National Observatory of Athens, Penteli, (Greece); Institute of Geophysics and Planetary Physics, University of California, Los Angeles (United States); Grande, M. [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon (United Kingdom)] [Rutherford Appleton Laboratory, Chilton, Didcot, Oxon (United Kingdom); Joselyn, J.A.; Singer, H.J. [Space Environment Center, NOAA, Boulder, Colorado (United States)] [Space Environment Center, NOAA, Boulder, Colorado (United States); McPherron, R.L. [Institute of Geophysics and Planetary Physics, University of California, Los Angeles (United States)] [Institute of Geophysics and Planetary Physics, University of California, Los Angeles (United States); Phillips, J.L. [NASA Johnson Space Flight Center, Houston, Texas (United States)] [NASA Johnson Space Flight Center, Houston, Texas (United States); Reeves, E.G. [Los Alamos National Laboratory, Los Alamos, New Mexico (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Rostoker, G. [Department of Physics, University of Alberta, Edmonton, Alberta (Canada)] [Department of Physics, University of Alberta, Edmonton, Alberta (Canada); Sharma, A.S. [Department of Astronomy, University of Maryland, College Park (United States)] [Department of Astronomy, University of Maryland, College Park (United States); Tsurutani, B.T. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena (United States)] [Jet Propulsion Laboratory, California Institute of Technology, Pasadena (United States)

1998-08-01

182

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

E-print Network

The relationship between storm dynamics and cloud-to-ground (CG) lightning characteristics in the convective region of the 10-11 June 1985 PRE-STORM (Preliminary Regional Experiment for Stormscale Operational and Research Meteorology) squall line...

Billingsley, David Brian

2012-06-07

183

The Dynamics of Titan's Convective Clouds  

NASA Astrophysics Data System (ADS)

Titan's deep convective clouds are the most dynamic phenomena known to operate within the atmosphere of the moon. Previous studies have focused primarily on the control of these storms by the large scale thermodynamic environment, especially methane abundance, which determines the amount of convective available potential energy (CAPE). This study looks at factors in addition to the thermodynamic environment that may have a first order impact on the evolution and structure of Titan's deep convective clouds. To the extent that thunderstorms on Earth provide a reasonable analog to the storms on Titan, it is well established that CAPE alone is insufficient to determine the structure and behavior of deep convection. Wind shear—both directional and speed—is also known to exert a first order effect. The influence of both CAPE and wind speed shear is typically expressed as the ratio of the two parameters in the form of the Bulk Richardson Number. On Earth, for a fixed value of CAPE, the addition of wind speed shear (i.e., the reduction of the Bulk Richardson Number) will tend to produce storms that are longer lived, tilted upshear with height, and multi-cellular in nature. These multi-cellular storms also tend to be more violent than storms generated in low wind speed shear environments: strong winds and large hail are common. The addition of directional shear (i.e., helicity) can transform the multi-cell storms into single, intense supercell storms. These are the storms associated typically associated with tornadoes. With respect to Titan, if there is a similar dependence on the Bulk Richardson Number, then this would have implications for how long Titan's storms live, how much precipitation they can produce, the area they cover, and the strength and duration of winds. A series of numerical simulations of Titan's deep convective clouds from the Titan Regional Atmospheric Modeling System are presented. A reasonable sweep of the parameter space of CAPE and shear for Titan is used to quantify the dependence of Titan's storms on the same parameters known to affect deep convection on Earth. The results of the simulations and the implications for Titan are then discussed.imulated convection in a calm (left) and wind shear environment (right). Cloud mixing ratio (g/kg) is shaded. Winds are indicated by vectors with a reference in the lower right of each panel.

Rafkin, S. C.

2012-12-01

184

Evaluation of the STORM model storm-time corrections for middle latitude  

NASA Astrophysics Data System (ADS)

Estimation of the ionospheric response to a geomagnetic disturbance and forecasting of the main ionospheric parameters is very useful for different radio communication purposes. As long as variations in the ionosphere are related in regular patterns, empirical models, such as the IRI model, sufficiently estimate corrections for the ionospheric effects on radio wave propagation. During a geomagnetic storm the variability of the ionospheric parameters increases substantially and makes forecasting more complicated. Recently the IRI2001 model incorporated a geomagnetic activity dependence based on an empirical Storm-Time Ionospheric Correction Model (STORM). This paper will present results of the STORM model validation for Northern and Southern Hemisphere middle latitudes. The created database incorporates 65 strong-tosevere geomagnetic storms, which occurred within the period 1995-2007. In our analysis we used data from some ionospheric stations (e.g., Pruhonice, El Arenosillo, Athens), which were not included in the development or the previous validation of the model. Hourly values of the F2 layer critical frequency, foF2, measured for 5-7 days during the main and recovery phases of each selected storm where compared with those generated by the IRI model. To perform a detailed comparison between observed values, medians and model-generated foF2 values the correlation coefficient, the normalised root-mean-square error (NRMSE), and the percentage improvement are calculated. Results of the comparative analysis show that the STORM model captures more effectively the negative phases of the summer ionospheric storms, while electron density enhancement during winter storms and changeover of the different storm phases is reproduced with lower accuracy. The STORM model corrections are less efficient for lowermiddle latitudes and severe geomagnetic storms. Effectiveness of the IRI2001 updating with the near-real time digisonde data is also analysed.

Buresova, Dalia; McKinnell, Lee-Anne; Sindelarova, Tereza; Blanco, Inés; de La Morena, Benito

185

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

E-print Network

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...

Saul, Scott Henry

2012-06-07

186

What caused the cool summer over northern Central Asia, East Asia and central North America during 2009?  

NASA Astrophysics Data System (ADS)

Cool and wet weather conditions hit northern Central Asia, East Asia and central North America during the 2009 summer in concert with a strong jet stream and a prominent meandering upper-level circulation in the Northern Hemisphere mid-latitudes despite the fact that the year 2009 is the fifth warmest year globally in the modern record. It is found that the conspicuous atmospheric variability in the entire Northern Hemisphere mid-latitudes during the summer of 2009 was caused by a combination of teleconnections associated with significant tropical thermal forcings, strong polar forcing, and interaction between high-frequency weather events and climate anomalies. The strong negative circumglobal teleconnection pattern associated with the deficient Indian summer monsoon rainfall and developing El Niño condition was the major contributor to the cool and wet summer in June. On the other hand, the July weather conditions were attributable to the high-latitude impact of the unprecedented negative Arctic Oscillation, together with the Rossby wave response to the subtropical heating generated by convective activities over the Western North Pacific summer monsoon region. It is also noted that enhanced storm track activity and frequent cold surges from high-latitudes may have played a role in the cool and wet summer over the regions of interest.

Ha, Kyung-Ja; Chu, Jung-Eun; Lee, June-Yi; Wang, Bin; Hameed, Saji N.; Watanabe, Masahiro

2012-12-01

187

An Observational and Modeling Analysis of the Indianapolis Urban Region Effects on Convective Thunderstorm Characteristics  

Microsoft Academic Search

An observational and modeling study is performed around the Indianapolis urban region to investigate potential urban land-surface effects on approaching convective events. A five year observational storm climatology in and around the Indianapolis urban region is examined using radar reflectivity and synoptic conditions. Each storm case is classified into synoptic set up, day \\/ night, and storm orientation \\/ propagation.

P. Pyle; D. Niyogi; M. Shepherd; P. Arya; F. Chen

2006-01-01

188

Spectrum of infrasound radiation from supercell storms  

E-print Network

We consider the generation of acoustic waves by turbulent convection and perform spectral analysis of a monopole source of sound related to the heat production by condensation of moisture. A quantitative explanation of the correlation between intensity of infrasound generated by supercell storms and later tornado formation is given. It is shown that low lifting condensation level (LCL) and high values of convective available potential energy (CAPE), which are known to favor significant tornadoes, also lead to a strong enhancement of supercell's low frequency acoustic radiation.

Akhalkatsi, Mariam

2010-01-01

189

Cassini/CIRS Observations of Temperatures in Saturn's Northern Storm Region  

NASA Astrophysics Data System (ADS)

In early December 2010, a large convective storm appeared in Saturn's northern hemisphere, centered near 40°N planetographic at the center of a westward jet (Sanchez-Lavega et al., 2011; Fisher et al. 2011). Storms of the observed magnitude, referred to as Great White Spots (GWS), are rare on Saturn, historically occurring once per Saturn year (30 Earth years), at equatorial or mid-northern latitudes during northern summer; the current storm is unusual in occurring during northern spring, roughly one season earlier than previous GWS outbursts. Thermal infrared observations, both groundbased and from the Cassini Composite Infrared Spectrometer (CIRS) orbiting Saturn, taken six weeks after the appearance of the storm, revealed significant changes to the thermal structure of Saturn's northern hemisphere (Fletcher et al., 2011). Cold temperatures were measured at the location of the disturbance in both the upper troposphere and stratosphere, and, surprisingly, hot spots to the east and west of the disturbance longitude with temperature contrasts of 16K, much larger than usual zonal temperature contrasts on Saturn. CIRS has continued to observe the latitude of the storm at one to two month intervals. These observations typically cover an approximately 10° wide latitude strip over one or two rotations of Saturn at a spatial resolution of 2° of arc in the CIRS mid-IR focal planes (600-1400 cm-1, 7-16?m). From these observations, we can retrieve temperatures in the upper troposphere between 50 and 200 mbar, and in the middle stratosphere between ~0.2 and 10 mbar. These observations show that temperatures in the stratospheric hot spots continued to increase through May 2011, when temperatures reached a peak of over 220 K, following the merger of two hot spots into one, with zonal temperature contrasts of 70 K. By mid-July, the maximum temperature in the hot spot had decreased to just under 200K. Furthermore, in May and July, the peak temperatures were at a pressure roughly two scale heights larger (lower in altitude) than in earlier observations - 2 mbar compared to 0.4 mbar. In the upper troposphere, temperature perturbations associated with the storm are around 5 to 10 K, larger than seen on Saturn prior to the storm, but much smaller than the temperature variations seen in the stratosphere.

Achterberg, R. K.; Hesman, B. E.; Bjoraker, G. L.; Fletcher, L.; Conrath, B. J.; Gierasch, P. J.; Flasar, F. M.

2011-12-01

190

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

USGS Publications Warehouse

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.

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

1998-01-01

191

Temperature measurements of a Martian local dust storm  

NASA Technical Reports Server (NTRS)

A technique for estimating the ground and near-ground atmospheric temperatures within a Martian local dust storm is presented. It is applied to soundings taken by the Viking orbiter infrared thermal mapper (IRTM) instrument at four times-of-day for one storm. Essentially, a comparison is made between infrared radiances emerging from the storm interior and those from the region surrounding the storm. Particle extinction properties are assumed to be independent of position in the storm region, and scattering properties must be selected arbitrarily. For the storm studied here, the ground temperature in the interior is at least 6 K cooler, whereas the near-ground atmospheric temperature may be less than or comparable to, those of the surroundings. The thermal structure of the storm interior did not change measurably between 11.5 and 16.6 hours local time. These observations favor theories of dust storm development in which regional winds rather than local, dust-driven convection initiate the mobilization of dust from the surface. It is also concluded that the optical properties of dust particles in this local storm differ from those observed by Mariner 9 during the 1971-1972 global dust storm.

Kahn, Ralph

1995-01-01

192

Observations and simulations of hurricane-spawned tornadic storms  

NASA Astrophysics Data System (ADS)

The occurrence of tornadoes within landfalling tropical cyclones has been recognized for a long time, with some reports extant from as early as 1811 [Tannehill, 1950]. However, the widespread rain, low clouds, and generally poor visibility attending most landfalling tropical cyclones has hindered direct observations of these tornadoes and impeded progress in understanding the character of their parent convective storms. Still, as more and more reports have become available, it has become possible to characterize the tornadoes and tornadic storms with growing accuracy.

McCaul, Eugene W., Jr.

193

Spectrum of infrasound radiation from supercell storms  

Microsoft Academic Search

We consider the generation of acoustic waves by turbulent convection and\\u000aperform spectral analysis of a monopole source of sound related to the heat\\u000aproduction by condensation of moisture. A quantitative explanation of the\\u000acorrelation between intensity of infrasound generated by supercell storms and\\u000alater tornado formation is given. It is shown that low lifting condensation\\u000alevel (LCL) and high

Mariam Akhalkatsi; Grigol Gogoberidze

2010-01-01

194

Arctic Summer Ice Processes  

NASA Technical Reports Server (NTRS)

The primary objective of this study is to estimate the flux of heat and freshwater resulting from sea ice melt in the polar seas. The approach taken is to examine the decay of sea ice in the summer months primarily through the use of spaceborne Synthetic Aperture Radar (SAR) imagery. The improved understanding of the dynamics of the melt process can be usefully combined with ice thermodynamic and upper ocean models to form more complete models of ice melt. Models indicate that more heat is absorbed in the upper ocean when the ice cover is composed of smaller rather than larger floes and when there is more open water. Over the course of the summer, floes disintegrate by physical forcing and heating, melting into smaller and smaller sizes. By measuring the change in distribution of floes together with open water over a summer period, we can make estimates of the amount of heating by region and time. In a climatic sense, these studies are intended to improve the understanding of the Arctic heat budget which can then be eventually incorporated into improved global climate models. This work has two focus areas. The first is examining the detailed effect of storms on floe size and open water. A strong Arctic low pressure storm has been shown to loosen up the pack ice, increase the open water concentration well into the pack ice, and change the distribution of floes toward fewer and smaller floes. This suggests episodic melting and the increased importance of horizontal (lateral) melt during storms. The second focus area is related to an extensive ship-based experiment that recently took place in the Arctic called Surface Heat Budget of the Arctic (SHEBA). An icebreaker was placed purposely into the older pack ice north of Alaska in September 1997. The ship served as the base for experimenters who deployed extensive instrumentation to measure the atmosphere, ocean, and ice during a one-year period. My experiment will be to derive similar measurements (floe size, open water, temporal change) using spaceborne SAR data obtained during the summer of 1998, and compare these results with an ocean and ice model of summer melt. Additional information is contained in the original.

Holt, Benjamin

1999-01-01

195

Rocket dust storms and detached layers in the Martian atmosphere  

E-print Network

Airborne dust is the main climatic agent in the Martian environment. Local dust storms play a key role in the dust cycle; yet their life cycle is poorly known. Here we use mesoscale modeling with radiatively-active transported dust to predict the evolution of a local dust storm monitored by OMEGA on board Mars Express. We show that the evolution of this dust storm is governed by deep convective motions. The supply of convective energy is provided by the absorption of incoming sunlight by dust particles, in lieu of latent heating in moist convection on Earth. We propose to use the terminology "rocket dust storm", or conio-cumulonimbus, to describe those storms in which rapid and efficient vertical transport takes place, injecting dust particles at high altitudes in the Martian troposphere (30 to 50 km). Combined to horizontal transport by large-scale winds, rocket dust storms form detached layers of dust reminiscent of those observed with instruments on board Mars Global Surveyor and Mars Reconnaissance Orbite...

Spiga, Aymeric; Madeleine, Jean-Baptiste; Määttänen, Anni; Forget, François

2012-01-01

196

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

NASA Astrophysics Data System (ADS)

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.

Lazar, Dora; Ihasz, Istvan

2013-04-01

197

Magnetic storms as a human infarction hazard: season effects  

NASA Astrophysics Data System (ADS)

There are a great number of clinical and statistical studies confirming that the myocardial infarction number rises during geomagnetic disturbances, which have a maximum of occurrence near equinox. Contrary to that, the analysis of the daily numbers of Moscow ambulance calls (1979-1981), related to the myocardial infarction, showed the strong winter maximum and summer minimum. The similar result we obtained by using the 25 year data (1970-1995) on the death from infarction in Bulgaria. We analyzed the biotropic efficacy of 129 geomagnetic storms and found that its hazard depends on the season. About of 90% of the winter time magnetic storms were accompanied by the infarction enhancement, but only ~ 3% of the summer magnetic storms led to the increasing of the cardiac problems. It means that the human organism stability to the "negative" influence of magnetic storms is stronger in summer than in winter. We also found that the different magnetic storm phases demonstrate the different hazard. As a rule, the storm main phase was not accompanied by the enhancement of the infarction number. However, the storm recovery phase typically leads to infarction increasing, particularly, if it was accompanied by the geomagnetic pulsation at periods of a few seconds.

Kleimenova, N.; Kozyreva, O.

2009-04-01

198

Modeling Convection  

NSDL National Science Digital Library

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.

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

2004-09-01

199

STORM WATER Residential  

E-print Network

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

California at Santa Cruz, University of

200

STORM SURGE WARNING SERVICE  

E-print Network

services In case of Storm surge and High Water on the Rivers Rhine or Meuse for the sector Dordrecht: · Storm surge has worse consequences for the water levels in the sector Dordrecht than High Water1 STORM SURGE WARNING SERVICE SVSD by Jan Kroos Rijkswaterstaat / RIKZ #12;2 Overview

Stoffelen, Ad

201

Storms in Space  

NASA Astrophysics Data System (ADS)

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.

Freeman, John W.

2012-11-01

202

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

E-print Network

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

Frew, Eric W.

203

Large Eddy Simulations of Severe Convection Induced Turbulence  

NASA Technical Reports Server (NTRS)

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.

Ahmad, Nash'at; Proctor, Fred

2011-01-01

204

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

205

Manifestation of Strong Geomagnetic Storms in the Ionosphere above Europe  

NASA Astrophysics Data System (ADS)

The solar wind effects on Earth environment are studied for their basic science value as well as for their crucial practical impact on human technological systems. Increased dissipation of solar wind energy in the near-Earth environment is a significant source of consequent perturbations in the upper atmosphere and ionosphere. This chapter addresses the ionospheric manifestation of geomagnetic storms induced by solar wind. Changes in the electron density distribution at the ionospheric F region heights above Europe during strong-to-severe geomagnetic storms, which occurred over present solar cycle, have been analysed. As for the seasonal preference, during storm main phase only negative phases dominate in summer, while during winter occurrence of both negative and positive phases is probable. Enhancements of electron density have been sometimes observed several hours before the onset of geomagnetic storm. Also the existence of few-hours-long periods during storm main phase, when the deviation of the electron density from median was insignificant, has been observed. Independent of the sign of the storm effect on F2 region ionisation, the effect on electron density at the F1 region heights at European higher middle latitudes has been found negative, if any at all. The F1 region response to magnetic disturbances also shows substantial summer/winter asymmetry. The stormy high latitude F region is most variable compared with middle and lower middle latitudes, being strongly influenced by magnetospheric processes, in particular, strong electric fields, which are usually present during geomagnetic storms. Several specific features of the storm-time high latitude ionosphere will briefly be mentioned including behaviour of ionospheric scintillations. The comparative analysis illustrates that the improved IRI-2001 model with the activated STORM option provides better description of the ionisation distribution above Europe under geomagnetic storm conditions. Nevertheless, our results show that model not always estimates correctly the storm phase and the magnitude of the effects on F region electron density

Buresova, D.; Lastovicka, J.; Franceschi, G. De

206

The development of convective instability in relation to convective activity and synoptic systems in AVE IV  

E-print Network

Administration's fourth Atmospheric Variability Experiment (AVE IV). The 3- and 6-h sounding intervals allowed time changes in convective stability to be studied in areas of convective storms. A stability development equation was derived and each term... was examined to determine when and where it made a significant contribution to the development process. The usefulness of satellite data in describing stability development and the processes effecting its change also was evaluated. Of the terms...

Davis, James Gregory

2012-06-07

207

Tropical Storm Ernesto over Cuba  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Microwave Image

These infrared, microwave, and visible images were created with data retrieved by the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite.

Infrared Image 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 Image 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.

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.

2006-01-01

208

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

209

Multiparameter radar and advanced microwave precipitation radiometer observations of tropical convection  

NASA Technical Reports Server (NTRS)

Combinations of both active and passive microwave sensors have been proposed for experiments such as the tropical rainfall measuring mission (TRMM). During the summer 1991 Convection and Precipitation/Electrification Experiment (CaPE) in central Florida, both cold- and warm-rain precipitation processes were studied with the NCAR CP-2 multiparameter radar, operating at 3 and 10 GHz. The Advanced Microwave Precipitation Radiometer (AMPR), which operates at 10.7, 19.35, 37.1, and 85.5 GHz, was flown aboard NASA's ER-2 high-altitude aircraft over storms being scanned by the CP-2 radar. Top-of-atmosphere multifrequency TB from the AMPR is presented along with coincident CP-2 radar observations. Joint analysis of both radar and radiometer data sets allows refinement of new and existing precipitation retrieval techniques which will utilize the multifrequency TB from an integrated spaceborne microwave radiometer/radar system.

Vivekanandan, J.; Turk, J.; Hood, R. E.; Griffin, V. L.; Lafontaine, F. J.; Bringi, V. N.; Spencer, R. W.

1992-01-01

210

Subtropical Storm Andrea  

NASA Technical Reports Server (NTRS)

The circling clouds of an intense low-pressure system sat off the southeast coast of the United States on May 8, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image. By the following morning, the storm developed enough to be classified as a subtropical storm, a storm that forms outside of the tropics, but has many of the characteristics--hurricane-force winds, driving rains, low pressure, and sometimes an eye--of a tropical storm. Although it arrived several weeks shy of the official start of the hurricane season (June 1), Subtropical Storm Andrea became the first named storm of the 2007 Atlantic hurricane season. The storm has the circular shape of a tropical cyclone in this image, but lacks the tight organization seen in more powerful storms. By May 9, the storm's winds reached 75 kilometers per hour (45 miles per hour), and the storm was not predicted to get any stronger, said the National Hurricane Center. Though Subtropical Storm Andrea was expected to remain offshore, its strong winds and high waves pummeled coastal states, prompting a tropical storm watch. The winds fueled wild fires (marked with red boxes) in Georgia and Florida. The wind-driven flames generated thick plumes of smoke that concentrated in a gray-brown mass over Tampa Bay, Florida. Unfortunately for Georgia and Florida, which are experiencing moderate to severe drought, Subtropical Storm Andrea was not predicted to bring significant rain to the region right away, according to reports on the Washington Post Website.

2007-01-01

211

A new insight on the cause of magnetic storms  

Microsoft Academic Search

A long outstanding problem in magnetospheric physics is the cause of magnetic storms. Traditionally, the ringcurrentbuildupisattributedtotheaccumulatedeects of energetic magnetospheric particles injected by frequent occurrence of magnetospheric substorms. Recent studies, however, suggest enhanced magnetospheric convection as thes ole cause. We employ for therst time therelatively new remote-sensing technique based on global monitoring of energetic neutral atom (ENA) emissions to address this

A. T. Y. Lui; R. W. McEntire; K. B. Baker

2001-01-01

212

Storm Alert: Latest Updates on Campus Closures ***STORM ALERT***  

E-print Network

Storm Alert: Latest Updates on Campus Closures 1 message ***STORM ALERT*** TROPICAL STORM ISAAC and another Storm Alert will be issued at 8 p.m. People should not return to campus until the all-clear has 26, 2012 9:53:18 AM Subject: Storm Alert: Latest Updates on Campus Closures #12;· Refrain from using

Miami, University of

213

Spatial analysis of storm depths from an Arizona raingage network  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

214

Convection Movies  

NSDL National Science Digital Library

This page, on the website of Stephane Labrosse of ENS Lyon, presents some examples of flow motions resulting from convection calculations in different situations. All are for infinite Prandtl number and free-slip boundary conditions on horizontal surfaces

Labrosse, Stephane; Lyon, Ens

215

Power grid disturbances and polar cap index during geomagnetic storms  

NASA Astrophysics Data System (ADS)

The strong geomagnetic storm in the evening of 30 October 2003 caused high-voltage power grid disturbances in Sweden that expanded to produce hour-long power line outage in Malmö located in the southern part of the country. This was not a unique situation. The geomagnetic storm on 13 March 1989 caused extensive disruptions of high-voltage power circuits especially in the Province of Quebec, Canada, but also to a lesser degree in Scandinavia. Similar events have occurred earlier, among others, during the great storms of 13-14 July 1982 and 8-9 February 1986. These high-voltage power grid disturbances were related to impulsive magnetic variations accompanying extraordinarily intense substorm events. The events were preceded by lengthy intervals of unusually high values of the Polar Cap (PC) index caused by enhanced transpolar ionospheric convection. The transpolar convection transports magnetic flux from the dayside to nightside which causes equatorward displacements of the region of auroral activity enabling the substorms to hit vital power grids. During the 30 October 2003 event the intense solar proton radiation disabled the ACE satellite observations widely used to provide forecast of magnetic storm events. Hence in this case the alarmingly high PC index could provide useful warning of the storm as a back-up of the missing ACE-based forecast. In further cases, monitoring the PC index level could provide supplementary storm warnings to the benefit of power grid operators.

Stauning, Peter

2013-06-01

216

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.

1996-01-01

217

Hubble Observes a New Saturn Storm  

NASA Technical Reports Server (NTRS)

This NASA Hubble Space Telescope image of the ringed planet Saturn shows a rare storm that appears as a white arrowhead-shaped feature near the planet's equator. The storm is generated by an upwelling of warmer air, similar to a terrestrial thunderhead. The east-west extent of this storm is equal to the diameter of the Earth (about 7,900 miles). Hubble provides new details about the effects of Saturn's prevailing winds on the storm. The new image shows that the storm's motion and size have changed little since its discovery in September, 1994.

The storm was imaged with Hubble's Wide Field Planetary Camera 2 (WFPC2) in the wide field mode on December 1, 1994, when Saturn was 904 million miles from the Earth. The picture is a composite of images taken through different color filters within a 6 minute interval to create a 'true-color' rendition of the planet. The blue fringe on the right limb of the planet is an artifact of image processing used to compensate for the rotation of the planet between exposures.

The Hubble images are sharp enough to reveal that Saturn's prevailing winds shape a dark 'wedge' that eats into the western (left) side of the bright central cloud. The planet's strongest eastward winds (clocked at 1,000 miles per hour from analysis of Voyager spacecraft images taken in 1980-81) are at the latitude of the wedge.

To the north of this arrowhead-shaped feature, the winds decrease so that the storm center is moving eastward relative to the local flow. The clouds expanding north of the storm are swept westward by the winds at higher latitudes. The strong winds near the latitude of the dark wedge blow over the northern part of the storm, creating a secondary disturbance that generates the faint white clouds to the east (right) of the storm center.

The storm's white clouds are ammonia ice crystals that form when an upward flow of warmer gases shoves its way through Saturn's frigid cloud tops. This current storm is larger than the white clouds associated with minor storms that have been reported more frequently as bright cloud features.

Hubble observed a similar, though larger, storm in September 1990, which was one of three major Saturn storms seen over the past two centuries. Although these events were separated by about 57 years (approximately 2 Saturnian years) there is yet no explanation why they apparently follow a cycle -- occurring when it is summer in Saturn's northern hemisphere.

The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

1994-01-01

218

The Impacts of Chihuahua Desert Aerosol Intrusions on Convective Clouds and Regional Precipitation  

NASA Astrophysics Data System (ADS)

Growing up in a desert region influenced by a monsoon system and experiencing, first-hand, dust storms produced by convective thunderstorms stimulated my interest in the study of the impacts of aerosols on clouds. Contrary to other studies which focus more on anthropogenic aerosols, I chose to investigate the role of natural aerosols in the deserts of North America. Moreover, the role played by aerosols in desert regions within the North American Monsoon domain has not received as much attention as in other monsoon regions around the world. This dissertation describes my investigation of the connection between mineral aerosols (dust storms) and monsoon rainfall in the deserts of the Southwestern United States and Northwestern Mexico. To develop the context for the study of the role of mineral dust in summer-time convection on a regional scale, large-scale dynamical processes and their impact on the inter-annual variability of monsoon rainfall were analyzed. I developed the climatology of monsoonal rainfall and dust storms using surface observations to determine which mesoscale features influence North American Monsoon rainfall in the Paso Del Norte region. The strongest correlations were found between sea surface temperatures over the Gulf of California, Gulf of California moisture surges and monsoon rainfall in the Paso Del Norte region. A connection to ENSO could not be clearly established despite analyzing twenty-one years of data. However, by breaking the data into segments, a strong correlation was found for periods of intense rainfall. Twenty-one case studies were identified in which dust storms were produced in conjunction with thunderstorms during the 2005 - 2007 monsoon seasons. However, in some cases all the conditions were there for rainfall to occur but it did not precipitate. I concluded that strong thunderstorm outflow was triggering dust storms. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem V3.1.1) was used to evaluate the model's sensitivity to the inclusion of aerosol effects on cloud drop formation and on direct radiative forcing. A comparison of the relative contribution of aerosol direct and indirect forcings in terms of differences in aerosol and cloud optical thicknesses, cloud water content, cloud droplet number, and short wave and long wave radiation, revealed that cloud cover is reduced. This suggests that Chihuahua desert dust affects cloud formation.

Apodaca, Karina

219

Atmospheric dynamics of Saturn's 2010 giant storm  

NASA Astrophysics Data System (ADS)

Saturn's Great White Spots are rare planetary-scale storms that have been observed only six times since 1876. The most recent Great White Spot appeared in December 2010 and has been studied from both ground-based and spacecraft observations. The storm developed into an enormous disturbance extending over 10,000km at cloud level, emitted intense electrostatic discharges over several months, and caused long-standing localized warming in the high stratosphere of about 60K. Here we analyse the dynamics of the storm's head using high-resolution imagery obtained by the Cassini spacecraft on 26 February 2011. We find strong winds with speeds up to 160ms-1 and organized into a divergent open anticyclone where massive cumulus-like cloud clusters interact with the ambient zonal flow to generate a storm front. The cloud clusters evolved over a timescale of hours, with cloud tops reaching 44km above the undisturbed environment. Simulations using a general circulation model, which includes Saturn's zonal winds, reproduce the observations when a persistent heat source is introduced, causing a high-pressure anomaly. We conclude that the complex phenomenology of a mature Great White Spot represents a natural response of the saturnian atmosphere to severe sustained convection in a sheared background flow.

García-Melendo, E.; Hueso, R.; Sánchez-Lavega, A.; Legarreta, J.; Del Río-Gaztelurrutia, T.; Pérez-Hoyos, S.; Sanz-Requena, J. F.

2013-07-01

220

Storm Window Treatments  

NSDL National Science Digital Library

Students will be asked to analyze a given set of data to determine the best storm window treatments for a local company to use when building a new homes. Students will be asked to write a letter to the company explaining how they ranked the storm window treatments.

2012-12-03

221

Dust storms in Turkmenistan  

Microsoft Academic Search

Dust storms are a phenomenon particularly common to the arid and semi-arid regions of Turkmenistan. The aridity of the climate, vast areas of sandy, solonchak and clayey deserts, sparse vegetation cover, and strong winds all favor the formation of dust storms. Long-term (60 years) data from 56 meteorological stations was analysed for the study of spatial distribution, frequency, seasonality and

L. Orlovsky; N. Orlovsky; A. Durdyev

2005-01-01

222

Structure of Highly Sheared Tropical Storm Chantal during CAMEX-4  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

223

A neural network model for the automatic detection and forecast of convective cells based on meteosat second generation data  

Microsoft Academic Search

The Mesoscale Convective Systems (MCSs) are often correlated with heavy rainfall, thunderstorms and hail showers, frequently causing significant damages. The most intensive weather activities occur during the maturing stage of the development, which can be found in the case of a multi-cell storm in the centre of the convective complex systems. These convective systems may occur in several different unstable

S. Puca; L. de Leonibus; F. Zauli; P. Rosci; L. Musmanno

2004-01-01

224

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

E-print Network

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 ...

McGraw-Herdeg, Michael (Michael P.)

2010-01-01

225

Convective Transport in the Earth's Outer Radiation Belts  

NASA Astrophysics Data System (ADS)

Geomagnetic storms are typically characterized by strong magnetospheric convection due to sustained periods of southward IMF BZ. During periods of strong convection the Alfvén layer, which separates the region of sunward convection from closed drift shells, is displaced earthward allowing plasmasheet electrons with energies in the 100s of keV direct access inside of geosynchronous orbit. Subsequent outward motion of the Alfvén boundary and adiabatic energization during the storm recovery period trap plasmasheet electrons on closed drift shells providing a source population for the outer radiation belts. Van Allen Probe observations of the 8-10 October 2012 geomagnetic storm and MHD test-particle simulations illustrating the morphology of this process will be presented. Results demonstrate the potential for formation of strong peaks in electron phase space density inside of geosynchronous due to global dynamics of magnetospheric fields.

Kress, B. T.; Hudson, M. K.; Paral, J.

2013-12-01

226

Observation and numerical simulation of a convective initiation during COHMEX  

NASA Technical Reports Server (NTRS)

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.

Song, J. Aaron; Kaplan, Michael L.

1991-01-01

227

Multisensor observations of an elevated mesoscale convective system with a low-level wave beneath its impacting rear-inflow jet  

Microsoft Academic Search

Elevated convective storms, where the source air is located above the boundary layer, are often associated with severe weather and the forecasting of such storms remains particularly challenging. Elevated mesoscale convective systems (MCSs) are relatively rare in the UK compared with, for example, the Great Plains of the USA. However, during the UK \\

John Marsham; Keith Browning; John Nicol; Doug Parker; Emily Norton; Alan Blyth; Ulrich Corsmeier; Felicity Perry

2010-01-01

228

Meteorology, Macrophysics, Microphysics, Microwaves, and Mesoscale Modeling of Mediterranean Mountain Storms: The M8 Laboratory  

NASA Technical Reports Server (NTRS)

Comprehensive understanding of the microphysical nature of Mediterranean storms can be accomplished by a combination of in situ meteorological data analysis and radar-passive microwave data analysis, effectively integrated with numerical modeling studies at various scales, from synoptic scale down through the mesoscale, the cloud macrophysical scale, and ultimately the cloud microphysical scale. The microphysical properties of and their controls on severe storms are intrinsically related to meteorological processes under which storms have evolved, processes which eventually select and control the dominant microphysical properties themselves. This involves intense convective development, stratiform decay, orographic lifting, and sloped frontal lifting processes, as well as the associated vertical motions and thermodynamical instabilities governing physical processes that affect details of the size distributions and fall rates of the various types of hydrometeors found within the storm environment. Insofar as hazardous Mediterranean storms, highlighted in this study by three mountain storms producing damaging floods in northern Italy between 1992 and 2000, developing a comprehensive microphysical interpretation requires an understanding of the multiple phases of storm evolution and the heterogeneous nature of precipitation fields within a storm domain. This involves convective development, stratiform transition and decay, orographic lifting, and sloped frontal lifting processes. This also involves vertical motions and thermodynamical instabilities governing physical processes that determine details of the liquid/ice water contents, size disi:ributions, and fall rates of the various modes of hydrometeors found within hazardous storm environments.

Starr, David O. (Technical Monitor); Smith, Eric A.

2002-01-01

229

New insights on geomagnetic storms from observations and modeling  

SciTech Connect

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.

Jordanova, Vania K [Los Alamos National Laboratory

2009-01-01

230

Identification of Robust Routes using Convective Weather Forcasts  

E-print Network

Convective weather is responsible for large delays and widespread disruptions in the U.S. National Airspace System (NAS), especially during summer months when travel demand is high. This has been the motivation for Air ...

Michalek, Diana

231

Identification of Robust Terminal-Area Routes in Convective Weather  

E-print Network

Convective weather is responsible for large delays and widespread disruptions in the U.S. National Airspace System, especially during summer. Traffic flow management algorithms require reliable forecasts of route blockage ...

Balakrishnan, Hamsa

232

Prompt penetration electric fields (PPEFs) and their ionospheric effects during the great magnetic storm of 30–31 October 2003  

Microsoft Academic Search

We explore the ionospheric effects of prompt penetration electric fields (PPEFs) for a variety of interplanetary magnetic field directions. We use the great magnetic storm of 30–31 October as an example of PPEF effects. For intense southward interplanetary magnetic fields (IMFs), inward plasma sheet convection occurs with the result of magnetospheric ring current formation and an intense magnetic storm. Concurrent

B. T. Tsurutani; O. P. Verkhoglyadova; A. J. Mannucci; A. Saito; T. Araki; K. Yumoto; T. Tsuda; M. A. Abdu; J. H. A. Sobral; W. D. Gonzalez; H. McCreadie; G. S. Lakhina; V. M. Vasyli?nas

2008-01-01

233

Decameter storm radiation. I. [solar radio bursts and noise storms  

NASA Technical Reports Server (NTRS)

A description is given of the evolution of six decametric storms which took place during the period from January to August, 1971. The storms described were observed with a swept frequency interferometer. The array consists of sixteen log-periodic antennas, equally spaced on a two mile east-west baseline. The association of storms with optical activity and photospheric fields is considered along with the relation of decametric storms to coronal magnetic fields and the association of storms with decimeter and meter wavelength activity. It is shown that decametric storms are always associated with storms at the meter and decimeter wavelengths.

Gergely, T. E.; Erickson, W. C.

1975-01-01

234

‘RCHX-1STORM’ first Slovenian meteorological rocket program  

Microsoft Academic Search

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

Aleksander Kerstein; Drago Matko; Amalija Trauner; Zvone Britovšek

2004-01-01

235

Modeling Convection  

ERIC Educational Resources Information Center

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…

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

2004-01-01

236

Summer Programs.  

ERIC Educational Resources Information Center

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,…

Toussaint, Isabella H.

237

Summer 2011  

Microsoft Academic Search

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

Eric G. Strauss

2011-01-01

238

Summer Skies  

ERIC Educational Resources Information Center

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…

Science Scope, 2005

2005-01-01

239

Probability forecasts for storm surges  

E-print Network

of a storm surge Users SVSD, DNZ, DZL, Water boards, KNMI G G G G Deltares DMI Workshop 28 August 2007G G G G Probability forecasts for storm surges Hoek van Holland: Probability forecasts from Deltares DMI Workshop 28 August 2007, Probability forecasts for storm surges 1 #12;G G G G Storm surge

Stoffelen, Ad

240

[Biotropic effects of geomagnetic storms and their seasonal variations].  

PubMed

A substantial effect of geomagnetic storms on human health with a confidential probability P = 0.95 was revealed. The quantitative estimates of the biotropic effect are presented. For example, the frequency of occurrence of bursts exceeding the average number of hospitalized patients with mental and cardiovascular diseases during magnetic storms increases approximately 2 times compared with quiet periods (based on the data on 1983-84). The frequency of occurrence of myocardial infarction, angina pectoris, violation of cardial rhythm, acute violation of brain blood circulation during storms increases 2.1; 1.6; 1.6; 1.5 times, respectively compared with magnetically quiet periods (based on the data of 1992-96). A similarity of the seasonal distribution of the magnitude of the biotropic effect is revealed in the case of myocardial infarction and the number of magnetic storms: a maximum in the equinox and a minimum in summer. PMID:11605400

Kuleshova, V P; Pulinets, S A; Sazanova, E A; Kharchenko, A M

2001-01-01

241

Dynamic Reconfiguration of Terminal Airspace During Convective Weather  

E-print Network

Dynamic Reconfiguration of Terminal Airspace During Convective Weather Diana Michalek and Hamsa research has largely focused on enroute airspace in clear weather conditions, the principle of better are often impacted by congestion due to convective weather, especially during summer months when travel

Gummadi, Ramakrishna

242

Winter Storm Fire Safety  

MedlinePLUS

... media accounts and ask your followers to share. Twitter #Winter storm fire #safetytip: keep fire hydrants near ... and standards, research, training and education. Follow us: Twitter Facebook YouTube More information on winter fire safety ...

243

Solar radio continuum storms  

NASA Technical Reports Server (NTRS)

Radio noise continuum emission observed in metric and decametric wave frequencies is discussed. The radio noise is associated with actively varying sunspot groups accompanied by the S-component of microwave radio emissions. It is shown that the S-component emission in microwave frequencies generally occurs several days before the emission of the noise continuum storms of lower frequencies. It is likely that energetic electrons, 10 to 100 Kev, accelerated in association with the variation of sunspot magnetic fields, are the sources of the radio emissions. A model is considered to explain the relation of burst storms on radio noise. An analysis of the role of energetic electrons on the emissions of both noise continuum and type III burst storms is presented. It is shown that instabilities associated with the electrons and their relation to their own stabilizing effects are important in interpreting both of these storms.

1974-01-01

244

Nontornadic convective wind fatalities in the United States  

Microsoft Academic Search

A database was compiled for the period 1977–2007 to assess the threat to life in the conterminous United States from nontornadic\\u000a convective wind events. This study reveals the number of fatalities from these wind storms, their causes, and their unique\\u000a spatial distributions. Nontornadic convective wind fatalities occur most frequently outdoors, in vehicles including aircraft,\\u000a or while boating. Fatalities are most

Alan W. BlackWalker; Walker S. Ashley

2010-01-01

245

Report Concerns: Storm Water Quality Hotline  

E-print Network

Report Concerns: Storm Water Quality Hotline: Please report any concerns, illegal dumping the possibility of impacts on storm water quality. Storm Water Run Off: Where does the storm water runoff go (at is UCSC managing storm water runoff and protecting storm water quality? (photo at right: storm drains

California at Santa Cruz, University of

246

Hurricane and Severe Storm Sentinel (HS3)  

NASA Astrophysics Data System (ADS)

HS3 is one of five projects in NASA's Earth Venture program. The goal of HS3 is to enhance our understanding of the processes that underlie hurricane intensity change in the Atlantic Ocean basin. HS3 is motivated by hypotheses related to the roles of the large-scale environment and storm internal processes in hurricane intensity change as well as the controversial role of the Saharan Air Layer (SAL) in tropical storm formation and intensification, the role of deep convection in the inner-core region of storms, and the evolution of storm structure and intensity during the process of transition into a more extratropical system. The HS3 objectives are: (1) to obtain critical measurements in the hurricane environment in order to identify the role of key factors such as large-scale wind systems (troughs, jet streams), Saharan air masses, African Easterly Waves and their embedded critical layers and (2) to observe and understand the three-dimensional mesoscale and convective-scale internal structures of tropical disturbances and cyclones and their role in intensity change. Past hurricane field campaigns have all faced the limitation of a relatively small sample of storms forming under a variety of scenarios and undergoing widely varying evolutions. The small sample is not only a function of tropical storm activity in any given year, but also the distance of storms from the base of operations. Addressing the science questions posed by HS3 requires sustained measurements over several years. HS3 will conduct a total of ten 30-hour flights during each of three one-month deployments using two NASA Global Hawk UASs. From mid-August to mid-September during 2012-2014, HS3 will be deployed from the NASA Wallops Flight Facility, providing access to unrestricted air space and unprecedented access to hurricanes over the Atlantic ocean. HS3 utilizes a suite of advanced instruments to measure key characteristics of the storm environment and the hurricane’s internal structures. The environmental payload will provide continuous sampling of temperature and relative humidity in the clear-air environment from the scanning High-resolution Interferometer Sounder (HIS), full tropospheric wind, temperature, and humidity profiles from the Advanced Vertical Atmospheric Profiling System (AVAPS) dropsonde system, continuous wind profiles in clear air from the TWiLiTE Doppler wind lidar, and aerosol and cloud layer vertical structure from the Cloud Physics Lidar (CPL). The over-storm payload measurements include three-dimensional wind and precipitation fields from the HIWRAP conically scanning Doppler radar, surface winds and rainfall from the Hurricane Imaging Radiometer (HIRAD) multi-frequency interferometric radiometer, and measurements of temperature, water vapor, and liquid water profiles, total precipitable water, sea-surface temperature, rain rates, and vertical precipitation profiles from the HAMSR microwave sounder. HS3 will provide a unique and comprehensive data set on a large number of Atlantic hurricanes to characterize the hurricane environment and internal structures. The HS3 measurements will be used enhance our understanding of hurricane intensification and, by coupling data analysis with both global and mesoscale modeling research, improve current Earth system modeling and prediction capabilities.

Braun, S. A.; Newman, P. A.; Vasques, M.

2010-12-01

247

Convection Currents  

NSDL National Science Digital Library

This demonstration provides an aesthetic way to view convection currents in fluids. Water warmed by an electric circuit mixes with the surrounding cooler water creating turbulence effects that bend light; the resulting swirling shadows can be projected onto a screen. The site provides an explanation of what happens and a simpler method to demonstrate the same effect. Materials needed and assembly instructions are also given. This activity is part of Exploratorium's Science Snacks series.

2008-06-19

248

Convection Demonstration  

NSDL National Science Digital Library

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.

Twin Cities Public Television, Inc.

2007-01-01

249

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

Microsoft Academic Search

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

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

250

Summer Reading  

NSDL National Science Digital Library

Summer is a great time to kick back with a good book. Try The Bailey School Kids Series... it\\'s Great! Bailey School Kids Jan Brett is my favorite artist. It takes longer to look at the pictures than it does to read the book. But it\\'s worth it. Jan Brett I love Bunnicula, almost as much as I love Harold. Find out ...

Roner, Mrs.

2005-03-31

251

Lightning location relative to storm structure in a supercell storm and a multicell storm  

Microsoft Academic Search

Relationships between lightning location and storm structure are examined for one radar volume scan in each of two mature, severe storms. One of these storms had characteristics of a supercell storm, and the other was a multicell storm. Data were analyzed from dual-Doppler radar and dual-VHF lightning-mapping systems. The distributions of VHF impulse sources were compared with radar reflectivity, vertical

Peter S. Ray; Donald R. MacGorman; W. David Rust; William L. Taylor; Lisa Walters-Rasmussen

1987-01-01

252

Summer Appendicitis  

PubMed Central

Acute appendicitis has been reported to be present throughout the year, but some particular months are associated with higher incidences. The aim of this study was designed to review previous studies and analyze the current knowledge and controversies related to seasonal variability of acute appendicitis, to examine whether appendicitis has an annual seasonal pattern. A search of the MEDLINE databases for English language publications over the period from 1970 to 2012 was conducted. This list was extended by including also references from a recent review of appendicitis epidemiology. We selected the studies, which were published in an English-language peer-reviewed journal, did not have intervention, were conducted for at least one year and had the outcome of histologically-confirmed appendicitis and those which reported case data temporally. A total of 30 titles and abstracts were screened for eligibility. Of these, 11 studies from 8 countries conducted across from 1970 to 2012 met the selection criteria and contributed to the systematic review. A seasonal pattern of appendicitis with a mostly predominant peak is seen during the summer months in all the countries (except Nigeria and Turkey). Appendicitis is more common in summer months. The existence of a seasonal pattern in the onset of appendicitis may be due to exposure to air pollution, decreasing fiber diet and increase in the incidence of gastrointestinal infections in summer. PMID:24669325

Fares, A

2014-01-01

253

Severe convection and lightning in subtropical South America By Kristen L. Rasmussen1  

E-print Network

and Blankenship, 2012]. It is also the location of intense mesoscale convective systems (MCSs) [Romatschke1 Severe convection and lightning in subtropical South America of the seasonal, diurnal, and extreme storm-related lightning in South America. � Preference for hail

Houze Jr., Robert A.

254

Trajectory analysis of Saudi Arabian dust storms  

NASA Astrophysics Data System (ADS)

Temporal and spatial characteristics of Saudi Arabian dust storms, with focus on associated air parcel trajectories, are investigated using station and gridded weather observations and remotely-sensed aerosol optical depth (AOD). For 13 focal stations, an extensive pool of 84-h backward trajectories is developed for dust storm days, and the trajectories are grouped into 3-5 representative clusters based on the K-means technique and Silhouette Coefficients. Saudi Arabian dust storms are most prominent during February-June, with a mid-winter peak along the southern coast of the Red Sea, spring peak across northern Saudi Arabia around the An Nafud Desert, and early summer peak in eastern Saudi Arabia around the Ad Dahna Desert. Based on backward trajectories, the primary local dust source is the Rub Al Khali Desert and the primary remote sources are the Saharan Desert, for western Saudi Arabia, and Iraqi Deserts, for northern and eastern Saudi Arabia. During February-April, the Mediterranean storm track is active, with passing cyclones and associated cold fronts carrying Saharan dust to Saudi Arabian stations along the northern coast of the Red Sea. Across Saudi Arabia, the highest AOD is achieved during dust storms that originate from the Rub Al Khali and Iraqi Deserts. Most stations are dominated by local dust sources (primarily Rub Al Khali), are characterized by three dominant trajectory paths, and achieve AOD values exceeding 1. In contrast, for stations receiving predominantly remote dust (particularly Saharan), 3-5 trajectory paths emerge and AOD values only reach approximately 0.6 as dust is lost during transport.

Notaro, Michael; Alkolibi, Fahad; Fadda, Eyad; Bakhrjy, Fawzieh

2013-06-01

255

The flywheel effect: Ionospheric currents after a geomagnetic storm  

SciTech Connect

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 authors investigate these flywheel' currents by simulating a storm which occurred on the 23rd of November 1982 using the National Center for Atmospheric Research Thermosphere Ionosphere General Circulation Model (NCAR-TIGCM). The resulting high-latitude, height-integrated Hall currents are dominated by the neutral-wind-driven component for several hours after the end of main phase of the storm. The direction of these currents is reversed from normal. Analysis of the neutral and ion components of this current system indicates that the neutral component may drive as much as 80% of the high-latitude current system immediately after the storm has ended, and may continue to dominate this system for 4 to 5 hours.

Deng, W.; Killeen, T.L.; Burns, A.G. (Univ. of Michigan, Ann Arbor (United States)); Roble, R.G. (National Center for Atmospheric Research, Boulder, CO (United States))

1991-10-01

256

SUMMER ESSENTIALS 2013 SUMMER ESSENTIALS 2013  

E-print Network

Life Policies Governing Summer College and SummerStart.............................13 Student Rights Rights and Responsibilities...................................15 Syracuse University Policies...................skate.syr.edu....................................................................6 LGBT Resources

Raina, Ramesh

257

On extreme geomagnetic storms  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

258

Solar Radiation Storm  

NSDL National Science Digital Library

This past week has offered much excitement for space weather scientists and enthusiasts, alike. On Friday July 14, a major flare shot off the surface of the sun, pummeling Earth with a massive solar-radiation storm that interfered with satellite and radio communications and delayed a Russian space launch. The flare was one of the most powerful of the current eleven-year solar cycle (and the biggest solar radiation event since 1989) and was followed by a coronal mass ejection -- "a blast of billions of tons of electrically charged atomic particles and magnetic energy hurled in the Earth's direction at 3 million miles an hour" (1). When a very powerful coronal mass ejection hits the Earth's magnetosphere, a shock wave can compress the magnetosphere and unleash a geomagnetic storm -- causing interference with electric power transmission and triggering beautiful aurorae. Friday's flare was one of three storms last week, and the biggest since a small solar storm made the news in June (see the June 9, 2000 Scout Report for additional resources). Although this weekend's storms have diminished, more activity is anticipated as the sunspot group that is producing flares (region 9077) will continue to face the earth for another week.

Payne, Laura X.

259

Energetic Ion Injection and Formation of the Storm-time Ring Current  

Microsoft Academic Search

Formation of the storm-time ring current is a consequence of injection of charged particles into and within the magnetosphere. It is generally accepted that the enhancement in the convection electric field is mainly responsible for the storm-time injection. In this paper we made an extensive study of the ring current ion injection through 3-D test particle trajectory calculations (TPTCs). We

L. Xie; Z. Y. Pu; X. Z. Zhou; S. Y. Fu; Q. G. Zong; T. Fritz

2003-01-01

260

Geomagnetic responses in high latitudes during the storm of july 15—16, 2000  

Microsoft Academic Search

The ionospheric equivalent currents in the high latitudes and the auroral electrojet system during the geomagnetic storm on\\u000a July 15–16, 2000 are analyzed by using geomagnetic data from IMAGE chain. The large-scale vortices of equivalent currents\\u000a are observed in the storm. The vortices on the dusk side of ionosphere correspond to four-celled pattern of plasma convection\\u000a associated with NBZ, region

Gengxiong Chen; Aimin Du; Wenyao Xu; Hongfei Chen; Minghua Hong; Fenglin Peng; Enqi Shi

2002-01-01

261

Winter Storm Fire Safety  

MedlinePLUS

... Garage (home) fires Heating Holidays, candles and Christmas trees Hotels and motels Novelty lighters Smoke alarms Smoking Sprinklers (fire) Summer Winter Wildfire Educational programs Planning for public ...

262

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

NASA Technical Reports Server (NTRS)

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.

Lupo, Kevin

2012-01-01

263

Great magnetic storms  

NASA Technical Reports Server (NTRS)

The five largest magnetic storms that occurred between 1971 to 1986 are studied to determine their solar and interplanetary causes. All of the events are found to be associated with high speed solar wind streams led by collisionless shocks. The high speed streams are clearly related to identifiable solar flares. It is found that: (1) it is the extreme values of the southward interplanetary magnetic fields rather than solar wind speeds that are the primary causes of great magnetic storms, (2) shocked and draped sheath fields preceding the driver gas (magnetic cloud) are at least as effective in causing the onset of great magnetic storms (3 of 5 events) as the strong fields within the driver gas itself, and (3) precursor southward fields ahead of the high speed streams allow the shock compression mechanism (item 2) to be particularly geoeffective.

Tsurutani, Bruce T.; Lee, Yen T.; Gonzalez, Walter D.; Tang, Frances

1992-01-01

264

Great magnetic storms  

SciTech Connect

The five largest magnetic storms that occurred between 1971 and 1986 are studied to determine their solar and interplanetary causes. All of the events are found to be associated with high speed solar wind streams led by collisionless shocks. The high speed streams are clearly related to identifiable solar flares. It is found that (1) it is the extreme values of the southward interplanetary magnetic fields rather than solar wind speeds that are the primary causes of great magnetic storms, (2) shocked and draped sheath fields preceding the driver gas (magnetic cloud) are at least as effective in causing the onset of great magnetic storms (3 of 5 events ) as the strong fields within the driver gas itself, and (3) precursor southward fields ahead of the high speed streams allow the shock compression mechanism (item 2) to be particularly geoeffective.

Tsurutani, B.T.; Yen Te Lee; Tang, F. (California Inst. of Tech., Pasadena, CA (United States)); Gonzalez, W.D.

1992-01-03

265

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

SciTech Connect

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.

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

1988-01-01

266

Pilot Convective Weather Decision Making in En Route Airspace  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

267

The impact of an intense summer cyclone on 2012 Arctic sea ice retreat Jinlun Zhang, Ron Lindsay, Axel Schweiger, and Michael Steele  

E-print Network

particularly vulnerable to storms. During the storm, ice volume decreased about twice as fast as usual, owing: What was the impact of the storm on the ice, and did it have a significant role in creating the newThe impact of an intense summer cyclone on 2012 Arctic sea ice retreat Jinlun Zhang, Ron Lindsay

Zhang, Jinlun

268

The impact of an intense summer cyclone on 2012 Arctic sea ice retreat Jinlun Zhang, Ron Lindsay, Axel Schweiger, and Michael Steele  

E-print Network

conditions that made the ice particularly vulnerable to storms. During the storm, ice volume decreased abouta). Given the intensity of the cyclone, we ask: What was the impact of the storm on the ice, and didThe impact of an intense summer cyclone on 2012 Arctic sea ice retreat Jinlun Zhang, Ron Lindsay

Lindsay, Ron

269

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

270

Tropical Storm Lee to Newfoundland  

NASA Video Gallery

This video shows Tropical Storm Lee as it made landfall in Louisiana and Mississippi on September 4, 2011. This storm produced flooding and tornadoes to the southern states all the way to flooding ...

271

Dynamics of Saturn’s great storm of 2010-2011 from Cassini ISS and RPWS  

NASA Astrophysics Data System (ADS)

Saturn’s quasi-periodic planet-encircling storms are the largest convecting cumulus outbursts in the Solar System. The last eruption was in 1990 (Sánchez-Lavega, A. [1994]. Chaos 4, 341-353). A new eruption started in December 2010 and presented the first-ever opportunity to observe such episodic storms from a spacecraft in orbit around Saturn (Fischer, G. et al. [2011]. Nature 475, 75-77; Sánchez-Lavega, A. et al. [2011]. Nature 475, 71-74; Fletcher, L.N. et al. [2011]. Science 332, 1413). Here, we analyze images acquired with the Cassini Imaging Science Subsystem (ISS), which captured the storm’s birth, evolution, and demise. In studying the end of the convective activity, we also analyze the Saturn Electrostatic Discharge (SED) signals detected by the Radio and Plasma Wave Science (RPWS) instrument. The storm’s initial position coincided with that of a previously known feature called the String of Pearls (SoPs) at 33°N planetocentric latitude. Intense cumulus convection at the westernmost point of the storm formed a particularly bright “head” that drifted at -26.9 ± 0.8 m s-1 (negative denotes westward motion). On January 11, 2011, the size of the head was 9200 km and up to 34,000 km in the north-south and east-west dimensions, respectively. RPWS measurements show that the longitudinal extent of the lightning source expanded with the storm’s growth. The storm spawned the largest tropospheric vortex ever seen on Saturn. On January 11, 2011, the anticyclone was sized 11,000 km by 12,000 km in the north-south and east-west directions, respectively. Between January and September 2011, the vortex drifted at an average speed of -8.4 m s-1. We detect anticyclonic circulation in the new vortex. The vortex’s size gradually decreased after its formation, and its central latitude shifted to the north. The storm’s head moved westward and encountered the new anticyclone from the east in June 2011. After the head-vortex collision, the RPWS instrument detected that the SED activities became intermittent and declined over ?40 days until the signals became undetectable in early August. In late August, the SED radio signals resurged for 9 days. The storm left a vast dark area between 32°N and 38°N latitudes, surrounded by a highly disturbed region that resembles the mid-latitudes of Jupiter. Using ISS images, we also made cloud-tracking wind measurements that reveal differences in the cloud-level zonal wind profiles before and after the storm.

Sayanagi, Kunio M.; Dyudina, Ulyana A.; Ewald, Shawn P.; Fischer, Georg; Ingersoll, Andrew P.; Kurth, William S.; Muro, Gabriel D.; Porco, Carolyn C.; West, Robert A.

2013-03-01

272

Direct Observations in the Dusk Hours of the Characteristics of the Storm Time Ring Current Particles During the Beginning of Magnetic Storms  

Microsoft Academic Search

The characteristic features of the initial enhancement of the storm time ring current particles in the evening hours are consistent with flow patterns resulting from a combination of inward convection, gradient drift, and corotation, which carries plasma sheet protons into low L values near midnight and the higher-energy proton component into the plasmasphere and through the evening hours. Data from

Paul H. Smith; R. A. Hoffman

1974-01-01

273

Mesoscale convective complex vs. non-mesoscale convective complex thunderstorms: a comparison of selected meteorological variables  

E-print Network

and organization and depended largely upon the availability of radar observations. The three basic types are the individual air mass thunderstorm, the thunderstorm cluster, and the squall line. Of these three, the squall line displayed the greatest organization... and generally covered the largest area. With the increas- ing use of meteorological satellites, however, a fourth type has been observed. Referred to as a mesoscale convective complex (MCC), this storm type is similar to the squall line in that it covers...

Hoofard, Michael Eugene

2012-06-07

274

Investigating the Importance of Viscous Interactions on Ionospheric Convection via Comparisons of Open-Closed Boundaries (OCBs) and Convection Reversal Boundaries (CRBs)  

NASA Astrophysics Data System (ADS)

Geomagnetic storms cause large global disturbances in the Earth's magnetosphere, during which large amounts of energy are deposited in the magnetotail and inner magnetosphere, producing an enhanced ring current and energising plasma to relativistic levels by poorly-understood excitation mechanisms. A previous study by Hutchinson et al. [2011] identified 143 geomagnetic storms over the last solar cycle (1997-2008) from the global SYM-H index and associated solar wind (SW) data from the Advanced Composition Explorer (ACE) spacecraft. Current work continues to use this dataset to investigate the characteristic ionospheric convection during magnetic storms via radar backscatter observed by the Super Dual Auroral Radar Network (SuperDARN). A superposed epoch analysis is completed using the map potential technique of Ruohoniemi and Baker [1998]. This technique has previously successfully been used to investigate substorm convection, however the technique has not particularly been employed for studies of geomagnetic storms nor has the model fit been applied to combined radar data from multiple storms for statistical studies rather than performing the analysis on an individual storm by storm basis. Latitude-Time-Velocity (LTV) plots, analogous to standard Range-Time-Intensity (RTI) plots, are used to visualise the results, which show the 'average' ionospheric response during different sized geomagnetic storms as the substorm control on the convection is mostly 'averaged out'. This, along with the cross-cap potential derived from the superposed SuperDARN results, is compared with similarly superposed auroral images from the IMAGE and POLAR spacecraft missions to better constrain the storm time coupling between the solar wind and magnetosphere. Results from the comparison of the convection reversal boundaries (derived from the SuperDARN data) and open-closed boundaries (from the auroral imagery) are presented to investigate the significance of a possible viscous interaction between the solar wind and the magnetosphere in addition to the normal reconnection-driven interaction.

Hutchinson, J. A.; Wright, D. M.; Milan, S. E.; Grocott, A.; Boakes, P. D.

2012-04-01

275

Convective Bursts and Hot Towers Observed During CAMEX-3 and CAMEX-4  

NASA Technical Reports Server (NTRS)

The role of convective bursts in the inner core regions of tropical storms has been if interest for many years with respect to their role in intensification. The structure of these convective bursts is best observed in satellite observations, but their structure has also been observed in some of the airborne radar studies over the past decade. Recently, a convective burst was documented during Hurricane Bonnie during NASA's Convection and Moisure Experiment-3 (CAMEX-3, 1998) conducted jointly with NOAA's Hurricane Field Program (Heymsfield et al., 2001). CAMEX-3 involved the NASA ER-2 high-altitude and DC-8 medium altitude aircraft instrumented with a variety of remote sensing instruments. The Bonnie convective burst was suggested to contribute intensification if ots warm core vased on radar measurements provided by the ER-2 Doppler Radar (EDOP). During the 2001 hurricane season, data sets form additional storms were collected during CAMEX-4. This paper documents the internal structure of convective bursts observed by EDOP and supporting measurements during foour storms (Bonnie, 1998; Georges, 1998; Chantal, 2001; Humberto, 2001) with respect to draft intensities, height profiles of reflectivity, location with respect to the storm center, occurence relative to the sotrm evolutjion, and upper level outlflows associated with the burst. These cases will be presented in the poster and will be compared with Bonnie's convective burst whic was associated with a strong subsiding current which appeared to contribute to the storm intensification. For one of the sotrms (Chantal), a very intense convective burst was nearly 100 km east of the low level circulation center and thus was infavorably located for intensifying the storm.

Heymsfield, Gerald

2002-01-01

276

Operation Desert Storm  

Microsoft Academic Search

This paper presents a description of the objectives, planning, observations, and reports of a Department of Veteran's Affairs Social Work Outreach Team's efforts to work with soldiers returning from Operation Desert Storm. The soldiers reported experiences with discrimination, low morale, sexual harassment, and fear.

Lola West; Susan O. Mercer; Edith Altheimer

1993-01-01

277

Desert Storm communications  

Microsoft Academic Search

An overview of the communication network that supported Operation Desert Storm is presented. The system, which maintained a 98% availability rate, supported 700000 telephone calls and 152000 messages per day. More than 30000 radio frequencies were managed to provide necessary connectivity and to ensure minimum interference. The roles of communications satellites, switched networks and terrestrial systems, and packet-switched networks and

J. S. Toma

1992-01-01

278

Desert Storm environmental effects  

Microsoft Academic Search

It is noted that after more than six months of operation of the Patriot launch station in the Saudi Arabian desert no problems that were attributed to high temperature occurred. The environmental anomalies that did occur were cosmetic in nature and related to dust and salt fog. It was concluded that the Desert Storm environmental effects were typical of worldwide

E. W. Kimball

1992-01-01

279

Implementing storm water plans  

Microsoft Academic Search

The emphasis in storm water discharge permits has changed from how to apply for a permit to how to comply with a permit. By far the most common approach in acquiring a permit is through general permits, which should be available in all states by the end of 1993. General permits will be issued because states and US Environmental Protection

Perrich

1993-01-01

280

Weather Stations: Storms  

NSDL National Science Digital Library

In this activity, learners test how cornstarch and glitter in water move when disturbed. Learners compare their observations with videos of Jupiter's and Earth's storm movements. This activity is one station that can be combined with other stations for an hour and half lesson on weather patterns on Jupiter and Earth.

Institute, Lunar A.; Nasa

2011-01-01

281

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.

282

Recovery from major storms  

SciTech Connect

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.

Holeman, J.S.

1980-01-01

283

Magnetic Storms and Aurora  

NSDL National Science Digital Library

This is a lesson to investigate auroras. Learners will plot and compare the amount of energy dissipated by auroras in the northern hemisphere with the recorded Kp index of magnetic storm severity. This is the sixteenth activity in the Exploring the Earth's Magnetic Field: An IMAGE Satellite Guide to the Magnetosphere educators guide.

284

Great magnetic storms  

Microsoft Academic Search

The five largest magnetic storms that occurred between 1971 and 1986 are studied to determine their solar and interplanetary causes. All of the events are found to be associated with high speed solar wind streams led by collisionless shocks. The high speed streams are clearly related to identifiable solar flares. It is found that (1) it is the extreme values

Bruce T. Tsurutani; Yen Te Lee; Frances Tang; W. D. Gonzalez

1992-01-01

285

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...

286

Stories from the Storm  

ERIC Educational Resources Information Center

For four months, St. Paul's Episcopal School in the Lakeview neighborhood of New Orleans, Louisiana remained closed after Hurricane Katrina ravaged the entire city in August 2005. The storm left St. Paul's campus under nine feet of water for two weeks, destroying many buildings and the entire first floor of the campus. As the only remaining art…

Smoczynski, Carol

2007-01-01

287

California's Perfect Storm  

ERIC Educational Resources Information Center

The United States today faces an economic crisis worse than any since the Great Depression of the 1930s. Nowhere is it sharper than in the nation's schools. Last year, California saw a perfect storm of protest in virtually every part of its education system. K-12 teachers built coalitions with parents and students to fight for their jobs and their…

Bacon, David

2010-01-01

288

Complex Weather Study to Target Summer Storm Forecasting  

NSF Publications Database

... IHOP2002 will examine how the latest technology can bridge the gaps in water-vapor sensing. Four of ... signals from the Global Positioning System (GPS) and other sources. Special high-end radiosondes ...

289

Effects of cumulus convection on the simulated monsoon circulation in a general circulation model  

SciTech Connect

The effect of cumulus convection on the Asian summer monsoon circulation is investigated, using a general circulation model. Two simulations for the summer months (June, July, and August) are performed, one parameterizing convection using a mass flux scheme and the other without convective parameterization. The results show that convection has significant effects on the monsoon circulation and its associated precipitation. In the simulation with the mass flux convective parameterization, precipitation in the western Pacific is decreased, together with a decrease in surface evaporation and wind speed. In the indian monsoon region it is almost the opposite. Comparison with a simulation using moist convective adjustment to parameterize convection shows that the monsoon circulation and precipitation distribution in the no-convection simulation are very similar to those in the simulation with moist convective adjustment. The difference in the large-scale circulation with and without convective parameterization is interpreted in terms of convective stabilization of the atmosphere by convection, using dry and moist static energy budgets. It is shown that weakening of the low-level convergence in the western Pacific in the simulation with convection is closely associated with the stabilization of the atmosphere by convection, mostly through drying of the lower troposphere; changes in low-level convergence lead to changes in precipitation. The precipitation increase in the Indian monsoon can be explained similarly. 29 refs., 12 figs.

Zhang, Guang Jun (Univ. of California, San Diego, La Jolla, CA (United States))

1994-09-01

290

Convective heater  

DOEpatents

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.

Thorogood, Robert M. (Macungie, PA)

1986-01-01

291

Convective heater  

DOEpatents

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.

Thorogood, Robert M. (Macungie, PA)

1983-01-01

292

Convective heater  

DOEpatents

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.

Thorogood, R.M.

1983-12-27

293

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

E-print Network

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

Xue, Ming

294

Forecasting Dust Storms - Version 2  

NSDL National Science Digital Library

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.

Comet

2010-12-22

295

Forecasting Dust Storms - Version 2  

NSDL National Science Digital Library

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.

Weingroff, Marianne

2007-02-02

296

Hurricane Sandy Storm Tide Mapper  

NSDL National Science Digital Library

United States Geological Survey (USGS) provides real-time map-based information from USGS storm tide sensors. The data is reflected on the Hurricane Sandy Tide Mapper. The mapper provides location information, site photos and data for storm tide and inland flooding. In addition, the data from these sensors is used to create models of the precise time the storm-tide arrived, how ocean and inland water levels changed during the storm, the depth of the storm-tide throughout the event, and how long it took for the water to recede.

297

Impacts of Nucleating Aerosol on Florida Storms. Part I: Mesoscale Simulations SUSAN C. VAN DEN HEEVER, GUSTAVO G. CARRI, WILLIAM R. COTTON, PAUL. J. DEMOTT, AND  

E-print Network

Impacts of Nucleating Aerosol on Florida Storms. Part I: Mesoscale Simulations SUSAN C. VAN DEN dust, which can serve as cloud condensation nuclei (CCN), giant CCN (GCCN), and ice-forming nuclei (IFN- centrations on the characteristics of convective storms and their subsequent anvil development, sensitivity

Collett Jr., Jeffrey L.

298

METEOR - an artificial intelligence system for convective storm forecasting  

SciTech Connect

An AI system called METEOR, which uses the meteorologist's heuristics, strategies, and statistical tools to forecast severe hailstorms in Alberta, is described, emphasizing the information and knowledge that METEOR uses to mimic the forecasting procedure of an expert meteorologist. METEOR is then discussed as an AI system, emphasizing the ways in which it is qualitatively different from algorithmic or statistical approaches to prediction. Some features of METEOR's design and the AI techniques for representing meteorological knowledge and for reasoning and inference are presented. Finally, some observations on designing and implementing intelligent consultants for meteorological applications are made. 7 references.

Elio, R.; De haan, J.; Strong, G.S.

1987-03-01

299

Observations of Florida Convective Storms Using Dual Wavelength Airborne Radar.  

National Technical Information Service (NTIS)

NASA conducted the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE) during July 2002 for improved understanding of tropical cirrus. One of the goals was to improve the understanding of cirrus gener...

G. M. Heymsfield, A. J. Heymsfield, L. Belcher

2004-01-01

300

The relationship of storm severity to directionally resolved radio emissions  

NASA Technical Reports Server (NTRS)

The objective was to provide continuous observation of atmospheric electrical activity occurring in association with tropical storms in the Gulf of Mexico. The observations were to include the location of all detected intracloud and cloud-to-ground lightning activity occurring in the storm. To provide synoptic scale coverage, a phase linear interferometer high frequency direction finder (HFDF) system was constructed and developed at Marshall Space Flight Center (MSFC). This was used in concert with the existing HFDF interferometer at the southwest research institute to provide lightning location data through triangulation. Atmospheric electrical events were synchronized through the use of satellite receivers at each site. The intent of the data analysis was to correlate the location of electrical centers of activity with radar and satellite imagry to identify areas of intense convection within the tropical storm system. Analysis of the hurricane Alicia data indicate a center of atmospheric electrical activity associated with the vortex of the storm. The center appears to rotate from the Northern side of the vortex to the Southern side during the period of observation. An analysis of the atmospheric electrical burst rates associated with hurrican Alicia indicates that the electrical activity appears to maximize at the time of greatest storm intensity, i.e., maximum winds and lowest central pressure.

Johnson, R. L.

1986-01-01

301

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

302

Indian Summer  

SciTech Connect

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.

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

1997-08-01

303

Oxidant enhancement in martian dust devils and storms: storm electric fields and electron dissociative attachment.  

PubMed

Laboratory studies, numerical simulations, and desert field tests indicate that aeolian dust transport can generate atmospheric electricity via contact electrification or "triboelectricity." In convective structures such as dust devils and dust storms, grain stratification leads to macroscopic charge separations and gives rise to an overall electric dipole moment in the aeolian feature, similar in nature to the dipolar electric field generated in terrestrial thunderstorms. Previous numerical simulations indicate that these storm electric fields on Mars can approach the ambient breakdown field strength of approximately 25 kV/m. In terrestrial dust phenomena, potentials ranging from approximately 20 to 160 kV/m have been directly measured. The large electrostatic fields predicted in martian dust devils and storms can energize electrons in the low pressure martian atmosphere to values exceeding the electron dissociative attachment energy of both CO2 and H2O, which results in the formation of the new chemical products CO/O- and OH/H-, respectively. Using a collisional plasma physics model, we present calculations of the CO/O- and OH/H- reaction and production rates. We demonstrate that these rates vary geometrically with the ambient electric field, with substantial production of dissociative products when fields approach the breakdown value of approximately 25 kV/m. The dissociation of H2O into OH/H- provides a key ingredient for the generation of oxidants; thus electrically charged dust may significantly impact the habitability of Mars. PMID:16805701

Delory, Gregory T; Farrell, William M; Atreya, Sushil K; Renno, Nilton O; Wong, Ah-San; Cummer, Steven A; Sentman, Davis D; Marshall, John R; Rafkin, Scot C R; Catling, David C

2006-06-01

304

Evolving dominant charge structures during upscale storm growth in West Texas on 4 June 2012  

NASA Astrophysics Data System (ADS)

The Deep Convective Cloud Chemistry (DC3) field campaign occurred from 15 May and 30 June 2012 with a primary goal of understanding the source of oxides of nitrogen (NOx) in the upper atmosphere due to lightning. In order to better understand this effect, it is necessary to better understand how the local environment can impact the polarity of the lightning in a storm. If polarity changes are driven by changes in electrification mechanisms, changes to the vertical distribution of the lightning channels and NOx source may result. One of the regions participating in DC3 extended from west Texas into central Oklahoma, where an arrangement of three Lightning Mapping Arrays (LMA) allowed for continuous analysis of electrification processes as storms moved across the region and through different local environments. On 4 June 2012 isolated storms initiated within range of the West Texas LMA and generated a mesoscale convective system, part of which dissipated over the West Texas LMA and Southwest Oklahoma LMA domains overnight. Initial storm cells developed within a relatively dry mid-level environment and were observed to contain a mid-level positive charge. However, later storm cells, both further east in deeper moisture and within areas that had previously been moistened by convection, were primarily observed to contain a mid-level negative charge. This presentation will detail the transition from initial discrete storm cells with mid-level positive charge regions and predominantly -IC flashes, to increased cellular coverage with a mixture of charge structures, to longer-lived multicellular clusters dominated by mid-level negative charge and +ICs at upper levels in the storm. These charge structures will be compared to proposed controls on storm electrification, including moisture variability in the mid-troposphere and its relationship to depletion of cloud liquid water.

Sullivan, V. C.; Bruning, E. C.; MacGorman, D. R.; Krehbiel, P. R.; Rison, W.; Edens, H. E.

2013-12-01

305

Dust Storm, Aral Sea  

NASA Technical Reports Server (NTRS)

The Aral Sea has shrunk to less than half its size since 1985. The Aral Sea receives little water (sometimes no water) from the two major rivers that empty into it-the Syr Darya and Amu Darya. Instead, the river water is diverted to support irrigation for the region's extensive cotton fields. Recently, water scarcity has increased due to a prolonged drought in Central Asia. As the Aral Sea recedes, its former sea bed is exposed. The Aral's sea bed is composed of fine sediments-including fertilizers and other agricultural chemicals-that are easily picked up by the region's strong winds, creating thick dust storms. The International Space Station crew observed and recorded a large dust storm blowing eastward from the Aral Sea in late June 2001. This image illustrates the strong coupling between human activities (water diversions and irrigation), and rapidly changing land, sea and atmospheric processes-the winds blow across the

2002-01-01

306

Winter Storm Lesson Plan  

NSDL National Science Digital Library

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 ...

S., Tasia

2010-09-23

307

Tropical Severe Local Storms  

NSDL National Science Digital Library

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.

Comet

2013-01-09

308

Ice Storm Supercomputer  

ScienceCinema

"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.

None

2013-05-28

309

Investigating Magnetic Storms  

NSDL National Science Digital Library

In this activity, students use an internet archive of data on the Earth's magnetic field to study the frequency of magnetic storms of different intensities during the year, and during the solar sunspot cycle. The archive contains values of the Kp scale, an index of how disturbed the Earth's magnetic field was, on average, over each three-hour period of the day. They will select their data, construct a bar graph with it, and answer questions on what their data reveals.

Odenwald, Sten

310

PROJECT STORM 2 - A \\  

Microsoft Academic Search

With a projected 20-year wastewater capex programme of over $1.4B, an annual wastewater tariff of $90M and a projected 20-year growth in population of over 30%, a sophisticated asset planning tool for supporting infrastructure decision making is vital to Watercare. Watercare's first dynamic wastewater network model, created in 1997 during Project Storm, was at the time the largest and most

Geoff Milsom; David Ward; Darren Wilson

311

Ice Storm Supercomputer  

SciTech Connect

"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.

None

2009-01-01

312

Urban effects on storm rainfall in Midwestern United States  

Microsoft Academic Search

A comprehensive 5-year field and analysis programme concerned with urban-induced effects on precipitation was recently completed at St Louis, Missouri, USA. Data obtained from operation of a network of 225 recording raingauges on 5200 km2 indicated an increase of approximately 30 per cent in summer rainfall in an area which is most frequently exposed to storms crossing the urban-industrial region.

Floyd A. Huff

313

Lightning location relative to storm structure in a supercell storm and a multicell storm  

NASA Technical Reports Server (NTRS)

Relationships between lightning location and storm structure are examined for one radar volume scan in each of two mature, severe storms. One of these storms had characteristics of a supercell storm, and the other was a multicell storm. Data were analyzed from dual-Doppler radar and dual-VHF lightning-mapping systems. The distributions of VHF impulse sources were compared with radar reflectivity, vertical air velocity, and their respective gradients. In the supercell storm, lightning tended to occur along streamlines above and down-shear of the updraft and reflectivity cores; VHF impulse sources were most concentrated in reflectivities between 30 and 40 dBZ and were distributed uniformly with respect to updraft speed. In the multicell storm, on the other hand, lightning tended to coincide with the vertical reflectivity and updraft core and with the diverging streamlines near the top of the storm. The results suggest that the location of lightning in these severe storms were most directly associated with the wind field structure relative to updraft and reflectivity cores. Since the magnitude and vertical shear of the environmental wind are fundamental in determining the reflectivity and wind field structure of a storm, it is suggested that these environmental parameters are also fundamental in determining lightning location.

Ray, Peter S.; Macgorman, Donald R.; Rust, W. David; Taylor, William L.; Rasmussen, Lisa Walters

1987-01-01

314

Report Concerns: Storm Water Quality Hotline  

E-print Network

Report Concerns: Storm Water Quality Hotline: Please report any concerns, illegal dump- ing into storm drains, or suspicious activi- ties that may cause environmental harm to the Storm Water Quality. Where do storm drains outfall? 2. How is UCSC managing and pro- tecting storm water quality? 3

California at Santa Cruz, University of

315

INTRODUCTION TO STORM SURGE Introduction to  

E-print Network

of storm surge. Too many exceptions to fit the scale: · Hurricane Katrina, a category 3 at landfall SURGE 3 STORM SURGE: BEFORE AND AFTER Before Hurricane Katrina After Hurricane Katrina Images courtesyINTRODUCTION TO STORM SURGE Introduction to Storm Surge National Hurricane Center Storm Surge Unit

316

Interplanetary origin of geomagnetic storms  

Microsoft Academic Search

Around solar maximum, the dominant interplanetary phenomena causing intense magnetic storms (Dststorms,\\u000a involving intense southward IMFs: the sheath region just behind the forward shock, and the CME ejecta itself. Whereas the\\u000a initial phase of a storm is caused by the

Walter D. Gonzalez; Bruce T. Tsurutani; Alicia L. Clúa de Gonzalez

1999-01-01

317

Deep convection in the Sahel : a focus on gust fronts  

NASA Astrophysics Data System (ADS)

Convection in the Sahel presents a diurnal variability that is influenced by deep convection systems like the Mesoscale Convective Systems (MCSs) and isolated storms or smaller convective systems. These smaller systems have drew less attention than the MCSs, even though they also play a role in the water cycle of this region, contribute to the monsoon dynamics, and to set the scales of the surface heterogeneities. During the African Monsoon Multidisciplinary Analysis (AMMA) intensive observation period in 2006, many of these smaller systems have been observed with the Massachusetts Institute of Technology (MIT) radar that was installed in Niamey, Niger. A systematic study of daytime convection observed during the month of July 2006 is carried out based on the MIT radar data and on the complementary observations given by the ARM mobile facility, in order to analyse the processes and mechanisms involved of deep convection initiation. The results highlight a large frequency of occurrence of the density currents, and their importance in the initiation of new convective cells. Based on this observational analysis and on results from Large Eddy Simulation (LES), density currents are specifically studied, with the aim at : (1) evaluating their frequency of occurrence, (2) assessing their ability to trigger new convective cells, (3) analysing the sensitivity of density currents velocity to land surface contrasts, (4) testing a simple model for their parametrization, (5) evaluating the ability of the LES to represent density currents.

Dione, Cheikh; Lothon, Marie; Campistron, Bernard; Sall, Saidou M.; Guichard, Françoise; Badiane, Daouda; Couvreux, Fleur

2014-05-01

318

Empirical STORM-E Model. [I. Theoretical and Observational Basis  

NASA Technical Reports Server (NTRS)

Auroral nighttime infrared emission observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite is used to develop an empirical model of geomagnetic storm enhancements to E-region peak electron densities. The empirical model is called STORM-E and will be incorporated into the 2012 release of the International Reference Ionosphere (IRI). The proxy for characterizing the E-region response to geomagnetic forcing is NO+(v) volume emission rates (VER) derived from the TIMED/SABER 4.3 lm channel limb radiance measurements. The storm-time response of the NO+(v) 4.3 lm VER is sensitive to auroral particle precipitation. A statistical database of storm-time to climatological quiet-time ratios of SABER-observed NO+(v) 4.3 lm VER are fit to widely available geomagnetic indices using the theoretical framework of linear impulse-response theory. The STORM-E model provides a dynamic storm-time correction factor to adjust a known quiescent E-region electron density peak concentration for geomagnetic enhancements due to auroral particle precipitation. Part II of this series describes the explicit development of the empirical storm-time correction factor for E-region peak electron densities, and shows comparisons of E-region electron densities between STORM-E predictions and incoherent scatter radar measurements. In this paper, Part I of the series, the efficacy of using SABER-derived NO+(v) VER as a proxy for the E-region response to solar-geomagnetic disturbances is presented. Furthermore, a detailed description of the algorithms and methodologies used to derive NO+(v) VER from SABER 4.3 lm limb emission measurements is given. Finally, an assessment of key uncertainties in retrieving NO+(v) VER is presented

Mertens, Christopher J.; Xu, Xiaojing; Bilitza, Dieter; Mlynczak, Martin G.; Russell, James M., III

2013-01-01

319

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

NASA Technical Reports Server (NTRS)

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.

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

2014-01-01

320

Draconid meteor storms  

NASA Astrophysics Data System (ADS)

Outbursts and storms in the October Draconid meteor shower occur because meteoroids from the parent periodic comet, 21P/Giacobini-Zinner, are not dispersed uniformly around the stream. The comet's orbital evolution has allowed meteoroidal material to be fed into the stream for the past few centuries and to be supplied for the next thousand years or more, but this depends on the nucleus continuing to be physically active. Various shower outbursts can be linked to the comet's observed activity during the past century.

Asher, D. J.; Steel, D. I.

2012-01-01

321

Hubble Tracks Jupiter Storms  

NASA Technical Reports Server (NTRS)

NASA's Hubble Space Telescope is following dramatic and rapid changes in Jupiter's turbulent atmosphere that will be critical for targeting observations made by the Galileo space probe when it arrives at the giant planet later this year.

This Hubble image provides a detailed look at a unique cluster of three white oval-shaped storms that lie southwest (below and to the left) of Jupiter's Great Red Spot. The appearance of the clouds, as imaged on February 13, 1995 is considerably different from their appearance only seven months earlier. Hubble shows these features moving closer together as the Great Red Spot is carried westward by the prevailing winds while the white ovals are swept eastward. (This change in appearance is not an effect of last July's comet Shoemaker-Levy 9 collisions with Jupiter.)

The outer two of the white storms formed in the late 1930s. In the centers of these cloud systems the air is rising, carrying fresh ammonia gas upward. New, white ice crystals form when the upwelling gas freezes as it reaches the chilly cloud top level where temperatures are -200 degrees Fahrenheit (- 130 degrees Centigrade).

The intervening white storm center, the ropy structure to the left of the ovals, and the small brown spot have formed in low pressure cells. The white clouds sit above locations where gas is descending to lower, warmer regions. The extent of melting of the white ice exposes varied amounts of Jupiter's ubiquitous brown haze. The stronger the down flow, the less ice, and the browner the region.

A scheduled series of Hubble observations will help target regions of interest for detailed scrutiny by the Galileo spacecraft, which will arrive at Jupiter in early December 1995. Hubble will provide a global view of Jupiter while Galileo will obtain close-up images of structure of the clouds that make up the large storm systems such as the Great Red Spot and white ovals that are seen in this picture.

This color picture is assembled from a series of images taken by the Wide Field Planetary Camera 2, in planetary camera mode, when Jupiter was at a distance of 519 million miles (961 million kilometers) from Earth. These images are part of a set of data obtained by a Hubble Space Telescope (HST) team headed by Reta Beebe of New Mexico State University.

This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

1995-01-01

322

Current understanding of magnetic storms: Storm-substorm relationships  

Microsoft Academic Search

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

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

323

Mantle Convection Modeling  

NSDL National Science Digital Library

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.

Livnat, Yarden; Utah, University O.

324

Colorful Convection Currents  

NSDL National Science Digital Library

In this activity, students create artifical convection currents using hot and cold water, food coloring, and bottles. A materials list, instructions, and a brief explanation of the convection phenomenon are included.

325

Added value of convection permitting seasonal simulations  

NASA Astrophysics Data System (ADS)

In this study the added value of a ensemble of convection permitting climate simulations (CPCSs) compared to coarser gridded simulations is investigated. The ensemble consists of three non hydrostatic regional climate models providing five simulations with ~10 and ~3 km (CPCS) horizontal grid spacing each. The simulated temperature, precipitation, relative humidity, and global radiation fields are evaluated within two seasons (JJA 2007 and DJF 2007-2008) in the eastern part of the European Alps. Spatial variability, diurnal cycles, temporal correlations, and distributions with focus on extreme events are analyzed and specific methods (FSS and SAL) are used for in-depth analysis of precipitation fields. The most important added value of CPCSs are found in the diurnal cycle improved timing of summer convective precipitation, the intensity of most extreme precipitation, and the size and shape of precipitation objects. These improvements are not caused by the higher resolved orography but by the explicit treatment of deep convection and the more realistic model dynamics. In contrary improvements in summer temperature fields can be fully attributed to the higher resolved orography. Generally, added value of CPCSs is predominantly found in summer, in complex terrain, on small spatial and temporal scales, and for high precipitation intensities.

Prein, A. F.; Gobiet, A.; Suklitsch, M.; Truhetz, H.; Awan, N. K.; Keuler, K.; Georgievski, G.

2013-11-01

326

Interannual Behavior of Large Regional Dust Storms  

NASA Astrophysics Data System (ADS)

We examine large regional dust storms in MCS and TES retrieved temperature profiles. There is significant repeatability with three regional storms (A, B and C) each Mars year. Each type of storm is distinct seasonally and in its behavior.

Kass, D. M.; Kleinboehl, A.; McCleese, D. J.; Schofield, J. T.; Smith, M. D.

2014-07-01

327

46 CFR 116.920 - Storm rails.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Storm rails. 116.920 Section 116.920 Shipping...49 PASSENGERS CONSTRUCTION AND ARRANGEMENT Rails and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must...

2013-10-01

328

46 CFR 108.221 - Storm rails.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 2011-10-01 false Storm rails. 108.221 Section 108.221 Shipping ...DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

2011-10-01

329

46 CFR 108.221 - Storm rails.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 2012-10-01 false Storm rails. 108.221 Section 108.221 Shipping ...DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

2012-10-01

330

46 CFR 169.329 - Storm rails.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Storm rails. 169.329 Section 169.329 Shipping...SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

2011-10-01

331

46 CFR 127.320 - Storm rails.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Storm rails. 127.320 Section 127.320 Shipping...SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in...

2012-10-01

332

46 CFR 169.329 - Storm rails.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Storm rails. 169.329 Section 169.329 Shipping...SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

2010-10-01

333

46 CFR 108.221 - Storm rails.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 false Storm rails. 108.221 Section 108.221 Shipping ...DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

2013-10-01

334

46 CFR 127.320 - Storm rails.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Storm rails. 127.320 Section 127.320 Shipping...SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in...

2013-10-01

335

46 CFR 108.221 - Storm rails.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 false Storm rails. 108.221 Section 108.221 Shipping ...DESIGN AND EQUIPMENT Construction and Arrangement Rails § 108.221 Storm rails. Each unit must have a storm rail in the...

2010-10-01

336

46 CFR 169.329 - Storm rails.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Storm rails. 169.329 Section 169.329 Shipping...SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

2013-10-01

337

46 CFR 116.920 - Storm rails.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Storm rails. 116.920 Section 116.920 Shipping...49 PASSENGERS CONSTRUCTION AND ARRANGEMENT Rails and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must...

2010-10-01

338

46 CFR 169.329 - Storm rails.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Storm rails. 169.329 Section 169.329 Shipping...SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

2012-10-01

339

46 CFR 177.920 - Storm rails.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Storm rails. 177.920 Section 177.920 Shipping...GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

2012-10-01

340

46 CFR 116.920 - Storm rails.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Storm rails. 116.920 Section 116.920 Shipping...49 PASSENGERS CONSTRUCTION AND ARRANGEMENT Rails and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must...

2011-10-01

341

46 CFR 177.920 - Storm rails.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Storm rails. 177.920 Section 177.920 Shipping...GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

2011-10-01

342

46 CFR 127.320 - Storm rails.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Storm rails. 127.320 Section 127.320 Shipping...SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in...

2010-10-01

343

46 CFR 177.920 - Storm rails.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Storm rails. 177.920 Section 177.920 Shipping...GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

2010-10-01

344

46 CFR 177.920 - Storm rails.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Storm rails. 177.920 Section 177.920 Shipping...GROSS TONS) CONSTRUCTION AND ARRANGEMENT Rails and Guards § 177.920 Storm rails. Suitable storm rails or hand grabs must...

2013-10-01

345

46 CFR 116.920 - Storm rails.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Storm rails. 116.920 Section 116.920 Shipping...49 PASSENGERS CONSTRUCTION AND ARRANGEMENT Rails and Guards § 116.920 Storm rails. Suitable storm rails or hand grabs must...

2012-10-01

346

46 CFR 127.320 - Storm rails.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Storm rails. 127.320 Section 127.320 Shipping...SUPPLY VESSELS CONSTRUCTION AND ARRANGEMENTS Rails and Guards § 127.320 Storm rails. Suitable storm rails must be installed in...

2011-10-01

347

Outreach Plans for Storm Peak Laboratory  

NASA Astrophysics Data System (ADS)

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.

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

2006-12-01

348

Mars Atmospheric Chemistry in Electrified Dust Devils and Storms  

NASA Technical Reports Server (NTRS)

Laboratory studies, simulations and desert field tests all indicate that aeolian mixing dust can generate electricity via contact electrification or "triboelectricity". In convective structures like dust devils or storms, grain stratification (or charge separation) occurs giving rise to an overall electric dipole moment to the aeolian feature, similar in nature to the dipolar electric field generated in terrestrial thunderstorms. Previous simulation studies [1] indicate that this storm electric field on Mars can approach atmospheric breakdown field strength of 20 kV/m. In terrestrial dust devils, coherent dipolar electric fields exceeding 20 kV/m have been measured directly via electric field instrumentation. Given the expected electrostatic fields in Martian dust devils and storms, electrons in the low pressure CO2 gas can be energized via the electric field to values exceeding the electron dissociative attachment energy of both CO2 and H2O, resulting in the formation of new chemical products CO and O- and OH and H- within the storm. Using a collisional plasma physics model we present a calculation of the CO/O- and OH/H- reaction and production rates. We demonstrate that these rates vary geometrically with ambient electric field, with substantial production of dissociative products when fields approach breakdown levels of 20-30 kV/m.

Farrell, W. M.; Delory, G. T.; Atreya, S. K.; Wong, A.-S.; Renno, N. O.; Sentmann, D. D.; Marshall, J. G.; Cummer, S. A.; Rafkin, S.; Catling, D.

2005-01-01

349

Hydromagnetic Theory of Geomagnetic Storms  

Microsoft Academic Search

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

A. J. Dessler; E. N. Parker

1959-01-01

350

Wireless Telegraphy and Magnetic Storms  

Microsoft Academic Search

A recent theory of auroras and magnetic storms attributes these phenomena to the action of a flash of ultraviolet light from the sun. The flash causes an unusual ionization in the Kennelly-Heaviside layer. Therefore, it is only daylight wireless circuits which are, or may be, disturbed at the commencement of the magnetic storm, the night circuits remaining normal until dawn

H. B. Maris; E. O. Hulbiurt

1929-01-01

351

Comets and Terrestrial Magnetic Storms  

Microsoft Academic Search

A recent theory of the authors attributed terrestrial magnetic storms and auroral displays to the effect of unusual flares of ultra-violet light from the sun falling upon the terrestrial atmosphere. Such flares would be expected to cause changes in comets, and therefore comet changes should be closely connected with magnetic storms. This connection is supported by the evidence brought out

H. B. Maris; E. O. Hulburt

1929-01-01

352

Ionospheric redistribution during geomagnetic storms  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

353

Ice storms and forest impacts.  

PubMed

Ice storms, or icing events, are important meteorological disturbances affecting forests over a surprisingly large portion of the USA. A broad belt extending from east Texas to New England experiences major ice storms at least once a decade; and truly major events occur in the heart of this belt once or twice a century. In the areas most affected, icing events are a factor that shapes stand composition, structure, and condition over wide areas. Impacts of individual storms are highly patchy and variable, and depend on the nature of the storm. Impacts also depend on how (or if) forest managers conduct subsequent salvage cuttings. Important research needs remain to be considered by the forest ecology and meteorology communities. At present, how ice storm frequency and severity may change with future climate change is unknown. PMID:11087029

Irland, L C

2000-11-15

354

Temporal Evolution of Saturn's Great White Spot Storm 2010-2011  

NASA Astrophysics Data System (ADS)

We report on the temporal evolution of a large cumulus storm that erupted on Saturn in early December of 2010. The new event marks the latest occurrence of the 30-year quasi-periodic giant storms on Saturn known as the Great White Spots (GWS), which last erupted in 1990. Cassini ISS camera first captured the storm on December 5th, 2010, and has since monitored the storm at a semi-regular interval. The current storm erupted at 33 degree N planetocentric latitude, and our measurements indicate that the storm's initial longitude coincided that of a feature called the String of Pearls (SoPs) first found using Cassini VIMS (Momary et al. 2006 DPS/AAS, Choi et al. 2009 Icarus 10.1029/2008JE003254), suggesting that the new GWS and SoPs may be causally related. Our ISS images between December 2010 and June 2011 show that the storm had a very bright leading edge, which drifted westward relative to the Voyager longitude system at 2.79 degree per Earth day, similar to that measured by Sanchez-Lavega et al (2011, Nature 10.1038/nature10203). Our new methane filter images (MT2 and MT3) show that a substantial amount of cloud material is lifted at the leading edge up to the stratosphere, which indicates highly energetic cumulus convective activities consistent with Fischer et al (2011, Nature 10.1038/nature10205)'s detection of lightning discharges in the radio frequencies. Our images also reveal vertical shear in the local wind fields around the storm. During the early phase of the storm a large dark oval formed near the leading edge of the storm and drifted westward at 0.85 degree per day on average between December 2010 and June 2011, which was also noted in CIRS observation (Fletcher et al. 2011, Science 10.1126/science.1204774). Our measurements show that the oval has an anticyclonic vorticity. The anticyclonic oval defined the eastern end of the storm activities. By late June 2011, the storm's leading edge collided with the anticyclonic oval after encircling the entire latitudinal band. After impacting the oval, the cumulus activities in the storm decreased, and the bright clouds that used to characterize leading edge are no longer present. We also compare the wind field before and after the storm, and examine the effects of the latest storm in the context of Saturn's global meteorology.

Sayanagi, K. M.; Ewald, S. P.; Dyudina, U. A.; Ingersoll, A. P.; Porco, C.; Muro, G. S.

2011-12-01

355

Clouds and Dust Storms  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 2 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

Image information: VIS instrument. Latitude 68.4, Longitude 180 East (180 West). 38 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

356

Climatic regimes of tropical convection and rainfall  

SciTech Connect

Annual distribution and phase propagation of tropical convection are delineated using harmonic and amplitude-phase characteristics analysis of climatological pentad mean outgoing longwave radiation and monthly frequencies of highly reflective cloud. An annual eastward propagation of peak rainy season along the equator from the central Indian Ocean (60[degrees]E) to Arafura Sea (130[degrees]E) is revealed. This indicates a transition from the withdrawal of the Indian summer monsoon to the onset of the Australian summer monsoon. Significant bimodal variations are found around major summer monsoon regions. These variations originate from the interference of two adjacent regimes. The convergence zones over the eastern North Pacific, the South Pacific, and the southwest Indian Ocean are identified as a marine monsoon regime that is characterized by a unimodal variation with a concentrated summer rainfall associated with the development of surface westerlies equatorward of a monsoon trough. Conversely, the central North Pacific and North Atlantic convergence zones between persistent northeast and southeast trades are classified as trade-wind convergence zones; which differ from the marine monsoon regime by their persistent rainy season and characteristic bimodal variation with peak rainy seasons occurring in late spring and fall. The roles of the annual march of sea surface temperature in the phase propagation and formation of various climatic regimes of tropical convection are also discussed. 34 refs., 8 figs., 1 tab.

Wang, Bin (Univ. of Hawaii, Honolulu, HI (United States))

1994-07-01

357

Microphysics, Meteorology, Microwave and Modeling of Mediterranean Storms: The M(sup 5) Problem  

NASA Technical Reports Server (NTRS)

Comprehensive understanding of the microphysical nature of Mediterranean storms requires a combination of in situ meteorological data analysis and radar-passive microwave data analysis, effectively integrated with numerical modeling studies at various scales, particularly from synoptic scale down to mesoscale. The microphysical properties of and their controls on severe storms are intrinsically related to meteorological processes under which storms have evolved, processes which eventually select and control the dominant microphysical properties themselves. Insofar as hazardous Mediterranean storms, highlighted by the September 25-28/1992 Genova flood event, the October 5-7/1998 Friuli flood event, and the October 13-15/2000 Piemonte flood event (all taking place in northern Italy), developing a comprehensive microphysical interpretation requires an understanding of the multiple phases of storm evolution and the heterogeneous nature of precipitation fields within the storm domains. This involves convective development, stratiform transition and decay, orographic lifting, and sloped frontal lifting proc esses. This also involves vertical motions and thermodynamical instabilities governing physical processes that determine details of the liquid/ice water contents, size distributions, and fall rates of the various modes of hydrometeors found within the storm environments. This paper presents detailed 4-dimensional analyses of the microphysical elements of the three severe Mediterranean storms identified above, investigated with the aid of SSM/I and TRMM satellite measurements (and other remote sensing measurements). The analyses are guided by nonhydrostatic mesoscale model simulations at high resolution of the intense rain producing portions of the storm environments. The results emphasize how meteorological controls taking place at the large scale, coupled with localized terrain controls, ultimately determine the most salient features of the bulk microphysical properties of the storms. These results have bearing on precipitation remote sensing from space, and the role of modeling in designing precipitation retrieval algorithms.

Smith, Eric A.; Fiorino, Steven; Mugnai, Alberto; Panegrossi, Giulia; Tripoli, Gregory; Starr, David (Technical Monitor)

2001-01-01

358

Moisture surges over the Gulf of California and relationships with convective activity  

NASA Astrophysics Data System (ADS)

The North American Monsoon (NAM) is characterized by widespread convective activity and rainfall that is tied to key synoptic and sub-synoptic atmospheric circulation features during summer - from mid-June to September. The core monsoon region, particularly over southwestern United States and around the Gulf of California (GoC), often experiences atmospheric phenomena recognized in the literature as "moisture surges". These moisture surges represent one of the most important sources of rainfall variability in the NAM core region with important implications in the hydroclimate and the water resources management in this semiarid region. Although there are a number of studies relating NAM synoptic-scale conditions with moisture surges and regional rainfall patterns, the interactions between atmospheric phenomena of differing scales still remains under-investigated. The overall objective of this research is to improve the understanding of how smaller-spatial scale atmospheric processes modify the evolution of larger-scale atmospheric conditions over the NAM domain. More specifically, this study aims to determine the relationship between organized mesoscale convective systems (MCSs) and moisture surges, and their associated synoptic forcings in the form of Tropical Easterly Waves (TEW), and eastern Pacific Tropical Storms (TS)/Tropical Cyclones (TC). Similarly, relationships were determined between MCSs and GoC low-level jet (GCLLJ). The present research uses three approaches to determine the links between MCSs and moisture surges. A first component of the research consisted of a detailed analyses of a well-observed moisture surge event that occurred during the North American Monsoon Experiment (NAME-2004). Analyses of aircraft flight-level data, together with other special and routine observations are used to describe the four-dimensional structure of this surge event. Theory and observations indicate that this surge's leading edge resembles a solitary Kelvin wave during its initial stages. MCS convective outflows in the central-GoC were observed to modify northern GoC surge variability and the GCLLJ intensity. The observations highlighted the role of convective activity in modulating the surge and its subsequent evolution. The second component of this research consists of a comprehensive climatological study using historical satellite-estimated MCSs, a multiyear set of surge events, the North American Regional Reanalysis (NARR) products, and microwave scatterometer SeaWinds (QuikSCAT) data. Climatological composites are created based on synoptic timescales features (such as TEWs and TSs/TCs) and intraseasonal variations (30-60 -day Madden-Julian Oscillation (MJO) variability), and are further stratified with respect to mesoscale rainfall variability in the NAMS core region. These results provided new insights into the nature of the GoC moisture flux variability and describe the influence of MCSs in modulating the intensity of moisture surges and the GCLLJ. Further, results revealed the role of MCSs in modulating the diurnal cycle of the GoC low-level circulation during "major surge", "minor surge", and "non-surge" environments. In the third and final component of this research, numerical simulation experiments were performed using the Advance Research Weather and Research Forecasting (ARW V3.0) model to investigate the sensitivity of the model to those physical representations associated with convective processes in surge and non-surge synoptic-scale environments. The approach consisted of simulating features associated with mesoscale convective processes on different synoptic-scale background flows (e.g. during moisture surge and non-surge conditions). In the interest of simplicity, convective outflows, typically resulting from MCS events, were replaced by Cold Bubbles (CBs). Although several assumptions were made to replace the effect of convective activity by those of the CBs, this model configuration permitted evaluating the impact that CBs have on the regional flow during surge a

Mejia-Valencia, John Fredy

359

ARkStorm: A West Coast Storm Scenario  

NASA Astrophysics Data System (ADS)

The United Stated Geological Survey (USGS) Multi-Hazards Demonstration Project (MHDP) is preparing a new emergency-preparedness scenario, called ARkStorm, to address massive U.S. West Coast storms analogous to those that devastated California in 1861-62. Storms of this magnitude are projected to become more frequent and intense as a result of climate change. The MHDP has assembled experts from the National Oceanic and Atmospheric Administration (NOAA), USGS, Scripps Institute of Oceanography, the State of California, California Geological Survey, the University of Colorado, the National Center for Atmospheric Research, and other organizations to design the large, but scientifically plausible, hypothetical scenario storm that would provide emergency responders, resource managers, and the public a realistic assessment of what is historically possible. The ARkStorm patterns the 1861 - 1862 historical events but uses modern modeling methods and data from large storms in 1969 and 1986. The ARkStorm draws heat and moisture from the tropical Pacific, forming Atmospheric Rivers (ARs) that grow in size, gain speed, and with a ferocity equal to hurricanes, slam into the U.S. West Coast for several weeks. Using sophisticated weather models and expert analysis, precipitation, snowlines, wind, and pressure data the modelers will characterize the resulting floods, landslides, and coastal erosion and inundation. These hazards will then be translated into the infrastructural, environmental, agricultural, social, and economic impacts. Consideration will be given to catastrophic disruptions to water supplies resulting from impacts on groundwater pumping, seawater intrusion, water supply degradation, and land subsidence. Possible climate-change forces that could exacerbate the problems will also be evaluated. In contrast to the recent U.S. East and Gulf Coast hurricanes, only recently have scientific and technological advances documented the ferocity and strength of possible future West Coast storms. A task of ARkStorm is to elevate the visibility of the very real threats to human life, property, and ecosystems posed by extreme storms on the U.S. West Coast. This enhanced visibility will help increase the preparedness of the emergency management community and the public to such storms. ARkStorm is scheduled to be completed by September 2010 and will be the basis of a state-wide emergency response drill, Golden Guardian, led by the California Emergency Management Agency in 2011.

Cox, D. A.; Jones, L. M.; Ralph, F. M.; Dettinger, M. D.; Porter, K.; Perry, S. C.; Barnard, P. L.; Hoover, D.; Wills, C. J.; Stock, J. D.; Croyle, W.; Ferris, J. C.; Plumlee, G. S.; Alpers, C. N.; Miller, M.; Wein, A.; Rose, A.; Done, J.; Topping, K.

2009-12-01

360

The News, Summer 1999-Summer 2000.  

ERIC Educational Resources Information Center

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,…

Robertson, Trische, Ed.

2000-01-01

361

Dust Storm in Syria  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-366, 20 May 2003

A dust storm rages in Syria Planum, south of the Labyrinthus Noctis troughs (at lower center) in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) composite of daily global images taken during the recent southern winter. In this view, water ice clouds are present over each of the five largest Tharsis volcanoes, Olympus Mons (right center), Alba Patera (upper center), Ascraeus Mons (near center), Pavonis Mons (toward lower left), and Arsia Mons (lower left). The summertime north polar residual water ice cap can be seen at the top of this picture. Sunlight illuminates the planet from the left.

2003-01-01

362

Storm Events Database  

NSDL National Science Digital Library

From the National Climatic Data Center comes the Storms Events Database. Events are included from 1993 to the present, but as is stated on the site, the site is usually 90-120 days behind the current month. Users first choose a state and then, if necessary, a county, date, and event type. Results can be limited by tornado type, hail size, wind speed, number of injuries or deaths, and even amount of property or crop damage. The generated report lists all of the events during the time period specified and, when clicked, contain specific information about that event. Although the reports can not be downloaded, this powerful resource can be an helpful addition to a researcher's toolbox.

363

Severe Convection II: Mesoscale Convective Systems  

NSDL National Science Digital Library

Mesoscale convective systems occur worldwide and year-round and are accompanied by the potential for severe weather and flooding. This module describes typical system evolution by examining squall line, bow echo, and MCC characteristics throughout their life cycles. This module has less emphasis on the physical processes controlling MCS structure and evolution than our previously released module, Mesoscale Convective Systems: Squall Lines and Bow Echoes. Instead, this newly updated module includes more material on tropical squall lines, MCC's, and on NWPâs ability to predict convective systems. The module starts with a forecast scenario and concludes with a final exam. Rich graphics, audio narration, and frequent interactions enhance the learning experience.

Comet

2004-09-24

364

Gradients of meteorological parameters in convective and nonconvective areas  

E-print Network

. Intensive examination of the gradients observed near squall lines revealed typical gradient patterns and trends in the magnitudes of the gradients associated with convective systems. Height gradients at 850 mb were largest ahead of the storms... in the vicinity of jet streams (Kreitzberg, 1968), or in squall lines (Fankhauser, 1969). It also was determined that direct analysis of geopotential height gradients on a mesoscale basis would not give reliable results because of the random errors in accuracy...

McCown, Milton Samuel

2012-06-07

365

Prediction and Identification of Flash Flood Storms in Colorado. Part I: Attributes of Environment and Storm Evolution  

NASA Astrophysics Data System (ADS)

Heavy rainfall and hail frequently occur in association with intense, summertime convective storms that form along the foothills and eastern plains of the Colorado Rocky Mountains. Heavy rainfall amounts over localized regions can result in flash flooding in mountain communities and in the dense urban areas along the Front Range, disrupting traffic, causing damage to property and in extreme events, resulting in loss of life. Various approaches have been taken over the years to provide the best possible estimations of quantitative precipitation (QPE) and nowcasts and short-term forecasts of heavy precipitation (QPN and QPF, respectively) in order to assess the potential for flash floods over the 0-6 hr time period and to accurately model and predict streamflow increases and runoff. Ten Colorado flash flood and hailstorm events that occurred during the period from 2008-2012 are examined in detail in Parts I and II of this study to benchmark our current understanding of the attributes and evolution of flash flood events and determine how to improve our prediction and identification of those storms that are likely to produce heavy rainfall of short duration over very specific regions and basins sensitive to flooding. In Part I of this study, we utilize instrumentation available from the Front Range Observational Network Testbed (FRONT) located along the Colorado Front Range. This testbed includes 5 dual-polarimetric Doppler S-band radars and a variety of operational and experimental surface, upper air, and satellite observing systems. These detailed observations provide high resolution observations of wind, temperature, moisture, stability, precipitation rate and accumulation. The events are characterized by environments with relatively high moisture content for the area, both in the boundary layer and at mid-levels and conditionally unstable atmospheres either over the plains or over the mountains, or both. Boundary layer and steering level winds were generally between 2.5 - 15 m/s (5-30 kts), so storms were either semi-stationary or not moving particularly fast. Numerous storms formed on these days, but the heaviest rainfall and flash flood resulted from merging storms, back-building storms, and the continual re-initiation of new storms over the same elevated terrain locations during the afternoon period. The collision of convergence boundaries over the plains and the enhancement of existing storms by convergence boundary passage resulted in the formation of large, semi-stationary storms that proceeded to rain heavily over the Denver urban area, and caused one fatality on one of the days. On another day, the storms that formed all seemed rather similar in character, but the rainfall associated with storms that passed over a recent fire burn area caused flooding in that sensitive land area. Identifying and improving the prediction of those specific storms that will produce the heaviest rainfall or case substantial flooding is challenging. Use of basic extrapolation techniques are not sufficient for prediction of heavy rainfall and flooding events (see Part II). Planned efforts include using the documented attributes of the ten heavy precipitation events to develop improved, location-specific, detection and prediction of heavy precipitation storms.

Roberts, Rita; Wilson, James

2013-04-01

366

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

NASA Astrophysics Data System (ADS)

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.

Tyrlis, Evangelos; Lelieveld, Jos

2014-05-01

367

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

Microsoft Academic Search

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

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

1976-01-01

368

Enhanced level of water vapor during dust storms over the Indo-Gangetic basin  

Microsoft Academic Search

The Asian desert regions including Sahara desert (Africa) are well known as one of the major sources of natural mineral dust aerosols in the atmosphere. Recent studies using ground data and satellites show that all major dust storms affecting the aerosol loading in the Indo-Gangetic (IG) basin during the pre-monsoon (summer) season invariably originate from these regions. But unlike dry

R. P. Singh; A. K. Prasad

2006-01-01

369

Steamship Portland: X-Storms  

NSDL National Science Digital Library

In this lesson students will discover what causes extreme storms such as the Portland Gale of 1898 and the Halloween Nor'easter of 1991. They will identify and explain three factors that contributed to extreme storm conditions in the northwest Atlantic Ocean, off New England, discover how to obtain real-time and historical meteorological data, and compare and contrast extra-tropical cyclones, tropical cyclones, and hybrid storms. This hands-on activity uses on-line data resources and includes: focus questions, learning objectives, teaching time, audio/visual materials needed, background information, learning procedures, evaluations, extensions, as well as resources and student handouts.

Goodwin, Mel

370

Centralized Storm Information System (CSIS)  

NASA Technical Reports Server (NTRS)

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.

Norton, C. C.

1985-01-01

371

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

NASA Astrophysics Data System (ADS)

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 10-12bar, which is much deeper than solar radiation penetrates.

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 y Navascués, D.; Parker, D.; International Outer Planet Watch Team; Akutsu, T.; Barry, T.; Beltran, J.; Buda, S.; Combs, B.; Carvalho, F.; Casquinha, P.; Delcroix, M.; Ghomizadeh, S.; Go, C.; Hotershall, J.; Ikemura, T.; Jolly, G.; Kazemoto, A.; Kumamori, T.; Lecompte, M.; Maxson, P.; Melillo, F. J.; Milika, D. P.; Morales, E.; Peach, D.; Phillips, J.; Poupeau, J. J.; Sussenbach, J.; Walker, G.; Walker, S.; Tranter, T.; Wesley, A.; Wilson, T.; Yunoki, K.

2011-07-01

372

An Observational and Modeling Analysis of the Indianapolis Urban Region Effects on Convective Thunderstorm Characteristics  

NASA Astrophysics Data System (ADS)

An observational and modeling study is performed around the Indianapolis urban region to investigate potential urban land-surface effects on approaching convective events. A five year observational storm climatology in and around the Indianapolis urban region is examined using radar reflectivity and synoptic conditions. Each storm case is classified into synoptic set up, day / night, and storm orientation / propagation. Of the 61 cases, 35 (57%) were observed to change storm composition (e.g., split, intensify, dissipate). Storm composition is also compared to storm characteristic in four surrounding rural regions within a 120 km radius of Indianapolis. Statistics conclude that the urban region effects storm characteristics when compared to two of the four surrounding rural locations examined. Storms that propagated through the urban region during the day were the most affected by the urban region with daytime storms changing 70% of the time and nighttime storms 30%. One specific case is examined during June 13 2005. The convection of interest formed several kilometers southwest of Indianapolis and well ahead of a potent upper level low pressure system in the Upper Great Plains region. As the storm propagated northeast across downtown Indianapolis near 0030 UTC, it intensified in dBZ base and tilted radar reflectivity. The base reflectivity at 0030 UTC directly over downtown was near 45 dBZ while the 15.1 degree radar tilt showed nearly 60 dBZ. This elevated dBZ core may be caused normal storm dynamics, or the urban heat island (UHI) may have also provided extra lift to storm. Radar derived precipitation amounts were largest over the northeast or downwind portion of the city. The Mesoscale Model 5 (MM5) and Weather Research and Forecasting Model (WRF) are used to investigate the June 13 case. THe MM5 and WRF simulations both depicted the event nearly 2 hours late and produced spurious convection prior to the event of interest, therefore leading to a difficult task to observe near storm conditions. The control simulation using the MM5 depicted an isolated area of convection similar to the observed; however the WRF simulated additional convection north and south of Indianapolis. Pre-spurious convection plots between the control and non-urban simulations near 1800 UTC show a more distinct change in the MM5 surface parameters, such as 2 m temperatures and surface fluxes when compared to the WRF. However, radar derived base reflectivity comparisons for the control and non-urban simulations are different with both models. When the urban region is removed, the simulated storm seen in the control passing over Indianapolis is not simulated. In addition, accumulated precipitation throughout the event of interest is less when the urban region is removed for both simulations, with the largest differences indicated in the WRF simulation where the convection was more widespread and stronger in intensity.

Pyle, P.; Niyogi, D.; Shepherd, M.; Arya, P.; Chen, F.

2006-05-01

373

Thermodynamic Bias in the Multimodel Mean Boreal Summer Monsoon* WILLIAM R. BOOS AND JOHN V. HURLEY  

E-print Network

Thermodynamic Bias in the Multimodel Mean Boreal Summer Monsoon* WILLIAM R. BOOS AND JOHN V. HURLEY of boreal summer monsoons. The strongest bias lies over South Asia, where the upper-tropospheric temperature the monsoon thermal maximum, suppressing moist convection and cooling the upper troposphere. In a climate

374

Report Concerns: Storm Water Quality Hotline  

E-print Network

into storm drains, or suspi- cious activities that may cause environ- mental harm to the Storm Water Qual and peak flows enhancing groundwater recharge storm water pollutant reductions Green Infrastructure: Refers to natural systems that capture, cleanse and reduce storm water runoff using plants, soils and mic crobes

California at Santa Cruz, University of

375

Storm Water Quality Please report any concerns,  

E-print Network

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

California at Santa Cruz, University of

376

Summer Programs for Educators  

ERIC Educational Resources Information Center

There are so many great ways to extend oneself professionally--or personally--over the summer. This paper presents several opportunities for summer 2009: (1) The Teacher-to-Teacher Initiative; (2) Courage to Teach; (3) University of South Carolina's Summer Institute in Computer Science; (4) Online Program in Online Teaching; and (5) College Board…

Curriculum Review, 2009

2009-01-01

377

Analyses of Storm Events in an Adirondack Watershed: a Combined Approach Using Stable Isotopes of Sulfate and Nitrate, Chemistry and Hydrology  

NASA Astrophysics Data System (ADS)

The Archer Creek catchment which is the major inlet to Arbutus Lake at the Huntington Forest in the Adirondack Mountains of New York has been the focus of intensive investigations on hydrological and biogeochemical interactions. We used hydrologic information, solute chemistry and isotopic composition of nitrate (? 15N and ? 18O) and sulfate (? 34S and ? 18O) to evaluate how four summer/early autumn storms affected surface water chemistry after a summer of unusually dry conditions in 2002. Precipitation amounts varied among the storms (Storm 1--Sept. 14-18, 19 mm; Storm 2--Sept. 21-24, 33 mm; Storm 3--Sept. 27-29, 43 mm; Storm 4--Oct. 16-21, 68 mm). With the four storms there was an increase in water yield from 2 to 14%. The first storms resulted in relatively small changes in water chemistry. With progressive storms the changes in water chemistry became more marked with particularly major changes in Cb (sum of base cations), sulfate, nitrate, DOC and pH. The marked changes in chemistry were also reflected in changes in the isotopic composition of sulfate and nitrate. The results indicate that especially for storms 3 and 4 that there was an important solute source most likely attributable to wetlands. The contributions of wetlands was evident due to the large increases in DOC during the storm and evidence of changes in S wetland constituents from both chemical and isotopic information. Although these late summer and fall storms do not play a major role in the overall annual mass balances of solutes for this watershed, these events have distinctive chemistry including depressed pH that have important consequences to watershed processes and the linkage of these processes to climate change.

Mitchell, M. J.; Piatek, K.; Mayer, B.; Kendall, C.; Page, B.; Christopher, S.

2004-05-01

378

EXOS D observations of enhanced electric fields during the giant magnetic storm in March 1989  

SciTech Connect

The authors report the observation of intense electric fields in the magnetosphere at altitudes of 2000 to 6000 km during and after the large magnetic storm on March 13-14, 1989. Such large fields are a manifestation of the inability of convecting plasma bodies from storms to penetrate to the earth. The measurements were made by two sets of double probes on the EXOS D satellite. A sharp peak in the poleward field was observed, with a magnitude of roughly 100 mV/m when projected to ionospheric heights.

Okada, T. [Toyama Prefectural Univ. (Japan); Hayakawa, H.; Tsuruda, K.; Nishida, A.; Matsuoka, A. [Institute of Space and Astronautical Science, Kanagawa (Japan)

1993-09-01

379

Mosquito Problems after a Storm  

E-print Network

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...

Johnsen, Mark

2008-08-05

380

Oscillatory thermocapillary convection  

NASA Technical Reports Server (NTRS)

We study thermocapillary and buoyant thermocapillary convection in rectangular cavities with aspect ratio A = 4 and Pr = 0.015. Two separate problems are considered. The first is combined buoyant thermocapillary convection with a nondeforming interface. We establish neutral curves for transition to oscillatory convection in the Re-Gr plane. It is shown that while pure buoyant convection exhibits oscillatory behavior for Gr is greater than Gr(sub cr) (where Gr(sub cr) is defined for the pure buoyant problem), pure thermocapillary convection is steady within the range of parameters tested. In the second problem, we consider the influence of surface deformation on the pure thermocapillary problem. For the range of parameters considered, thermocapillary convection remained steady.

Mundrane, Michael R.; Zebib, Abdelfattah

1994-01-01

381

Easterly Wind Storms over Israel  

Microsoft Academic Search

Summary   Continental wind storms are common along the Mediterranean coast. Along the northern coast they are mostly cold, similar\\u000a to the Bora or the Mistral, and along the southern coast they are mostly warm, e.g., the Ghibli or the Shirocco. At the eastern\\u000a Mediterranean basin and the Levant region, these storms are intermittently warm and cold during the same season

H. Saaroni; B. Ziv; A. Bitan; P. Alpert

1998-01-01

382

Hurricane Katrina Storm Surge Reconnaissance  

Microsoft Academic Search

Hurricane Katrina August 23-30, 2005 was one of the costliest and deadliest hurricanes to ever strike the United States, impacting low-lying coastal plains particularly vulnerable to storm surge flooding. Maximum storm surges, overland flow depths, and inundation distances were measured along the Gulf Coast of Florida, Alabama, Mississippi, and Louisiana. The vehicle-based survey was complemented by inspections with the reconnaissance

Hermann M. Fritz; Chris Blount; Robert Sokoloski; Justin Singleton; Andrew Fuggle; Brian G. McAdoo; Andrew Moore; Chad Grass; Banks Tate

2008-01-01

383

Hurricane and Severe Storm Lenticular  

NSDL National Science Digital Library

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.

384

Corotating magnetospheric convection  

Microsoft Academic Search

The longitudinal asymmetry of the Io plasma torus, as predicted by the magnetic-anomaly model and observed by Earth-based optical astronomy, provides a driving mechanism for a corotating convection system in Jupiter's magnetosphere. Here we deduce some qualitative properties of this convection system from the general equations that govern a steady state corotating convection system (although we expect that time-dependent effects

T. W. Hill; A. J. Dessler; L. J. Maher

1981-01-01

385

Atmospheric Processes: Convection  

NSDL National Science Digital Library

In this two-part activity, students observe the phenomenon of convection and the fact that air can behave as a fluid like water, only less dense. They should understand that convection currents are found in many places and on many scales, such as huge convection currents in the atmosphere, oceans, and even in the Earth's interior, or as smaller convection currents that can be found in a cup of hot cocoa or a fish tank. Lists of materials, instructions, variations on the experiments, observations, and questions are provided. This activity can be performed as a demonstration by the teacher, or older students can conduct the experiments themselves.

2005-03-10

386

Equator-to-pole temperature differences and the extra-tropical storm track responses of the CMIP5 climate models  

NASA Astrophysics Data System (ADS)

This paper aims to understand the physical processes causing the large spread in the storm track projections of the CMIP5 climate models. In particular, the relationship between the climate change responses of the storm tracks, as measured by the 2-6 day mean sea level pressure variance, and the equator-to-pole temperature differences at upper- and lower-tropospheric levels is investigated. In the southern hemisphere the responses of the upper- and lower-tropospheric temperature differences are correlated across the models and as a result they share similar associations with the storm track responses. There are large regions in which the storm track responses are correlated with the temperature difference responses, and a simple linear regression model based on the temperature differences at either level captures the spatial pattern of the mean storm track response as well explaining between 30 and 60 % of the inter-model variance of the storm track responses. In the northern hemisphere the responses of the two temperature differences are not significantly correlated and their associations with the storm track responses are more complicated. In summer, the responses of the lower-tropospheric temperature differences dominate the inter-model spread of the storm track responses. In winter, the responses of the upper- and lower-temperature differences both play a role. The results suggest that there is potential to reduce the spread in storm track responses by constraining the relative magnitudes of the warming in the tropical and polar regions.

Harvey, B. J.; Shaffrey, L. C.; Woollings, T. J.

2014-09-01

387

New opportunities for the study of Mediterranean storms: the unique capabilities of the Global Hawk aircraft  

NASA Astrophysics Data System (ADS)

Airborne measurements have often played a pivotal role in unravelling critical processess and improving our understanding of the genesis and development of atmospheric disturbances. The availability of innovative aerial platforms now opens new perspectives for the scientific research. One of these platforms is the high altitude long endurance unmanned aircraft Global Hawk (GH), which has unique capabilities in terms of altitude, range of operation, diurnal coverage and flexibility. The GH has an endurance of 31 hrs, a service ceiling of 20000 m and can host a payload of 680 kg. Since it can operate at altitudes close to the boundary conditions of radiative processes, can follow the diurnal variation of aerosol and clouds, can rapidly deploy new instruments with space-time coverage comparable to space-borne ones, it is a platform which is at the same time complementary and competitive with satellites. In fact it combines the short time deployment of aircraft instruments with the global coverage of satellite instruments, while its flight altitude allows better spatial resolution than a satellite and its endurance provides a sufficiently broad overview at a scale relevant for sinoptic meteorology studies. NASA has recently acquired two of such unmanned high altitude aircraft to address a variety of Earth Science objectives, and Italy has a decade long experience of stratospheric in-situ and remote sensing science missions using the Russian M-55 "Geophysica" high altitude piloted aircraft. There is a common interest in a bilateral cooperative program in climate change science using the GH. The collaboration between NASA and Italian scientific institutions may offer the opportunity of deploying the GH over the Mediterranean Basin. The Mediterranean area is of particular interest under many respects. As instance, it would be of great interest to measure, when possible, the 3-dimensional structure and evolution of the aerosol content over the Mediterranean, with particular emphasis on Saharan Air Layer (SAL) events. The frequent occurrence of such events, influencing the development of heavy precipitation systems in the region, as they do for hurricane genesis in the Atlantic west of Africa, promts the study of their impact on microphysical processes during precipitation formation; on lower and upper atmosphere destabilization stemming respectively from the production of a deep mixed layer of near zero potential vorticity and from the associated capping warm layer; and on their radiative impact leading to an enhanced heating of the lower troposphere due to solar radiation absorption by the Saharan dust itself. A different area of investigation would be the study of origin and fate of strong mesoscale disturbances originating in the area during the end of Summer and Fall period. In fact, while most Mediterranean storms have classic baroclinic origins, there are intense mesoscale convective storms which form and evolve into warm core structures deriving their energy directly from the warm sea surface in a fashion similar to tropical cyclones, e.g. hurricanes and typhoons. This type of tropical-like storms have been named Medicanes: understanding their origin and development is of utmost importance in view of their potential changing response in relationship to expected climate changes since it has been speculated that these Mediterranean storms would become more frequent and more vigorous in the near future due to the Mediterranean sea-surface temperature increase that is (probably) already occurring because of global warming. Remote sensing instrumentation (radars, microwave radiometers, lidars) is a primary tool to address this issue from a high-flying platform, to improve the understanding of the thermodynamics, dynamics, and microphysics of clouds, by measuring the evolution of their 3-dimensional thermodynamical, dynamical, and microphysical structures and the 3-dimensional structure and evolution of the aerosol content. The long endurance of the GH will allow the study of cloud systems following their evolution ov

Cairo, F.; Curry, R. E.; Carli, B.

2009-09-01

388

Mechanisms initiating deep convection over complex terrain during COPS.  

SciTech Connect

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.

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

389

Urban Modification of Thunderstorms: An Observational Storm Climatology and Model Case Study for the Indianapolis Urban Region*  

E-print Network

convergence and convection as well as in simulated base reflectivity, surface energy balance (through sensibleUrban Modification of Thunderstorms: An Observational Storm Climatology and Model Case Study for the Indianapolis Urban Region* DEV NIYOGI,1 PATRICK PYLE,1,# MING LEI,1 S. PAL ARYA,# CHANDRA M. KISHTAWAL,1

Niyogi, Dev

390

2B.1 SHIP RADAR OBSERVATIONS OF A DEVELOPING TROPICAL STORM IN THE EAST PACIFIC Robert Cifelli  

E-print Network

that was collected on 10 September, 2001 as the ship passed through an easterly wave which later developed the change in precipitation vertical structure as the ship passed through regions of significant convection2B.1 SHIP RADAR OBSERVATIONS OF A DEVELOPING TROPICAL STORM IN THE EAST PACIFIC Robert Cifelli 1

Rutledge, Steven

391

The Relative Influence of Aerosols and Midlevel Dryness on Deep Convective Morphology  

NASA Astrophysics Data System (ADS)

Several recent studies of aerosol impacts on deep convection suggest that environmental conditions, including humidity, vertical wind shear, and instability, may modulate the precipitation response to aerosol loading. The goal of this research is to investigate the relative sensitivity of deep convective morphology to increasing aerosol concentrations and midlevel dryness. These conditions are common in developing severe weather situations such as those that occur near the dryline or in high plains of the United States. This goal is addressed through the use of idealized cloud-resolving model simulations. A common storm splitting pattern is simulated wherein the right moving storm becomes a dominant, cyclonically rotating supercell, and the left-moving storm evolves into a multicellular cluster. The relative impacts of aerosol loading and midlevel dryness on different types of organized deep convection within the same domain can therefore be addressed and will be presented. Sensitivity tests demonstrate that the right-moving storm transitions from a classic supercell to a low-precipitation supercell with increasing dryness aloft; the supercell storm structure is relatively insensitive to aerosol perturbations. The results also suggest that midlevel dryness exerts a stronger control than aerosol concentrations on the precipitation resulting from the left-moving multicellular cluster. However, the left-moving cluster is more sensitive than the supercell to aerosol perturbations through aerosol impacts on the cold pool strength and subsequent dynamical forcing.

Grant, Leah; van den Heever, Susan

2014-05-01

392

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

Microsoft Academic Search

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

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

2007-01-01

393

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

394

Exploring the land-ocean contrast in convective vigor using islands F.J.ROBINSON  

E-print Network

, with islands represented by regions of uniform surface heat flux only (no orography or aerosolsExploring the land-ocean contrast in convective vigor using islands F.J.ROBINSON S.C.SHERWOOD D and 85 GHz) observations over islands of increasing size, to those simulated by a model. Observed storms

Kirshbaum, Daniel

395

Stratosphere-troposphere exchange in a midlatitude mesoscale convective complex 1. Observations  

Microsoft Academic Search

On June 28, 1989, a severe thunderstorm over North Dakota developed into a squall line and then into a mesoscale convective complex (MCC) with overshooting tops as high as ~14 km and a cirrus anvil that covered more than 300,000 km2. In this paper we describe the trace gas concentrations prior to, in, and around the storm; paper 2 presents

Olga Poulida; Russell R. Dickerson; Andrew Heymsfield

1996-01-01

396

SYNOPTIC ENVIRONMENTS AND CONVECTIVE MODES ASSOCIATED WITH SIGNIFICANT TORNADOES IN THE CONTIGUOUS UNITED STATES  

E-print Network

1 SYNOPTIC ENVIRONMENTS AND CONVECTIVE MODES ASSOCIATED WITH SIGNIFICANT TORNADOES. Prentice Iowa State University Ames, IA 1. INTRODUCTION Tornado forecasting has evolved considerably since the formation of the Severe Local Storms (SELS) Center of the United States Weather Bureau in the early 1950s

397

Radial transport of storm time ring current ions  

SciTech Connect

Radial transport of energetic ions for the development of the main phase of geomagnetic storms is investigated with data from the medium energy particle analyzer (MEPA) on the Charge Composition Explorer (CCE) spacecraft, which monitored protons (E[sub p] > 56 keV), helium ions (E[sub He] > 72 keV), and the carbon-nitrogen-oxygen group, which is mostly dominated by oxygen ions (E[sub O] > 137 keV). From a study of four geomagnetic storms, we show that the flux increase of these ions in the inner ring current region (L [approx lt] 5) can be accounted for by an inward displacement of the ring current population by [approximately]0.5 to 3.5 R[sub E]. There is a general trend that a larger inward displacement occurs at higher L shells than at lower ones. These results are in agreement with previous findings. The radially injected population consists of the prestorm population modified by substorm injections which occur on a much shorter rime scale than that of a storm main phase. It is also found that the inward displacement is relatively independent of ion mass and energy, suggesting that the radial transport of these energetic ions is effected primarily by convective motion from a large electric field or by diffusion resulting from magnetic field fluctuations. 27 refs., 5 figs.

Lui, A.T.Y. (Johns Hopkins Univ., Laurel, MD (United States))

1993-01-01

398

Auroral oval equatorward boundary during strong magnetic storms  

NASA Astrophysics Data System (ADS)

Data has been collected for selected strong magnetic storms during which auroras were seen from ground at middle- and low-latitudes as reported by amateur observers all over the world Auroral reports from ground were compared with auroral images from space Timed Image Polar and in situ measurements of plasma and magnetic electric fields in the disturbed inner magnetosphere A new version of the Weimer2005 electric potential model gives the boundary that defines the low-latitude edge of both the convection electric field and the magnetic perturbation due to the field-aligned currents We tried to find out whether it is possible to predict auroral oval position during strong magnetic storms using this improved ionospheric electrodynamic model A quite good compatibility between FAC pattern and oval position has been found This suggests that during strong magnetic storm Weimer2005 FAC model may be used to predict equatorward boundary of the auroral oval We also compared the observed low-latitude oval boundaries with projections of Alfven layer for plasma sheet electrons Particle trajectories were traced using T04 s magnetic field model and Weimer 2005 electric field model for given solar wind conditions Results will be discussed

Bojanowska, M.; Hubert, B.; Nowakowski, R.

399

Variations in the age of Arctic sea-ice and summer sea-ice extent Ignatius G. Rigor1,2  

E-print Network

. On time scales of days to weeks, wind stresses from storms produce ridges of sea-ice and areas of open. The number of storms that any given parcel of ice has experienced is cumulative, and hence the amountVariations in the age of Arctic sea-ice and summer sea-ice extent Ignatius G. Rigor1,2 and John M

Rigor, Ignatius G.

400

Is Titan's Dune Orientation Controlled by Tropical Methane Storms?  

NASA Astrophysics Data System (ADS)

Titan’s equatorial regions are covered by eastward oriented linear dunes. This direction is opposite to mean surface winds simulated by Global Climate Models (GCMs) at these latitudes, oriented westward as trade winds on Earth [1, 2].Here, we propose that Titan’s dune orientation is actually determined by equinoctial tropical methane storms producing a coupling with superrotation and dune formation. Using meso-scale simulations of convective methane clouds [3, 4] with a GCM wind profile featuring the superrotation [5, 6], we show that Titan’s storms should produce fast eastward gust fronts above the surface. Such gusts dominate the aeolian transport. Using GCM wind roses and analogies with terrestrial dune fields [7], we show that Titan's dune growth occurs eastward under these conditions. Finally, this scenario combining global circulation winds and methane storms can explain other major features of Titan's dunes (i.e. divergence from the equator, size and spacing).References:[1] Lorenz et al.: The Sand Seas of Titan: Cassini RADAR Observations of Longitudinal Dunes, Science (2006)[2] Lorenz & Radebaugh: Global pattern of Titan’s dunes: Radar survey from the Cassini prime mission, Geophysical Research Letter (2009)[3] Barth & Rafkin.: TRAMS: A new dynamic cloud model for Titan’s methane clouds, Geophysical Research Letter (2007)[4] Barth & Rafkin.: Convective cloud heights as a diagnostic for methane environment on Titan, Icarus (2010)[5] Charnay & Lebonnois: Two boundary layers in Titan's lower troposphere inferred from a climate model, Nature Geoscience (2012)[6] Lebonnois et al.: Titan global climate model: A new 3-dimensional version of the IPSL Titan GCM, Icarus (2012)[7] Courrech du Pont, Narteau & Gao: Two modes for dune orientation, Geology (2014)

Charnay, Benjamin; Barth, Erika; Rafkin, Scot; Narteau, Clément; Lebonnois, Sébastien; Rodriguez, Sébastien; Courrech du Pont, Sylvain; Lucas, Antoine

2014-11-01

401

2013 Geomagnetic Storm Observations in the Arctic and Antarctic  

NASA Astrophysics Data System (ADS)

During recent 2013 geomagnetic storms, several tongue of ionization (TOI) events have been observed with polar maps of total electron content (TEC) derived from the global network of GNSS receivers. The TOI plasma originates from plasma that has been transported from the mid-latitudes by a feature known as storm enhanced density (SED). The SED plasma separates from the base of the enhanced mid-latitude ionosphere in the afternoon-dusk sector, and forms a plume that carries the plasma westward to the noon-time cusp. The TOI, as observed by GNSS, extends through the dayside cusp, across the polar cap to the night side, in both hemispheres. The TOI is a source of ionospheric irregularities and its distribution across the high latitude ionosphere is controlled by plasma convection. Here, TOI observations are shown using GNSS TEC polar plots overlaid onto SuperDARN HF radar observations of the high-latitude convection pattern. The locations where HF scatter is observed in the presence of TOI plumes are examined. In addition, we overlay observations of scintillation collected by specially equipped GNSS receivers. We explore the similarities between TOI events observed simultaneously in the two hemispheres and examine the time history of the gradients and irregularities. Finally, we report on cases where the position of the SED base stays fixed in latitude and longitude as the earth rotates. This observation is shown below in Figure 1 and holds true in both hemispheres. We correlate these observations to changes in the IMF geomagnetic field. Illustration of fixed position of SED base in March 17, 2013 storm in Northern and Southern Hemispheres.

Coster, A. J.; Thomas, E. G.; Baker, J. B.; Ruohoniemi, J.; Erickson, P. J.; Foster, J. C.

2013-12-01

402

Pie-Pan Convection  

NSDL National Science Digital Library

In this activity, students observe fluid motion and the formation of convection cells as a solution of soap and water is heated. This procedure can be performed as a demonstration by the teacher, or older students can conduct the experiment themselves. A list of materials, instructions, and a description of the convective process are included.

2005-03-10

403

Effects of explicit atmospheric convection at high CO2  

PubMed Central

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

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

2014-01-01

404

GPS TEC and scintillation measurements from the polar ionosphere during the October 2003 storm  

NASA Astrophysics Data System (ADS)

Severe ionospheric storms occurred at the end of October 2003. During the evening of 30 October a narrow stream of high electron concentration plasma crossed the polar cap in the antisunward ionospheric convection. A GPS scintillation receiver in the European high arctic, operating at 1.575 GHz, experienced both phase and amplitude scintillation on several satellite-to-ground links during this period. Close examination of the GPS signals revealed the scintillation to be co-located with strong gradients in Total Electron Content (TEC) at the edge of the plasma stream. The gradient-drift instability is a likely mechanism for the generation of the irregularities causing some of the scintillation at L band frequencies during this storm. The origin of the high TEC is explored and the possible implications of the work for scintillation forecasting are noted. The results indicate that the GPS scintillation over Svalbard can originate from traceable ionospheric plasma structures convecting from the American sector.

Mitchell, C. N.; Alfonsi, L.; De Franceschi, G.; Lester, M.; Romano, V.; Wernik, A. W.

2005-05-01

405

Impact of land surface properties on convection in a 40 day convection-permitting simulation over West Africa  

NASA Astrophysics Data System (ADS)

Land surface properties influence the life cycle of convective systems across West Africa via space-time variability in sensible and latent heat fluxes. Previous observational and modelling studies have shown that areas with strong mesoscale variability in vegetation cover or soil moisture induce coherent structures in the daytime planetary boundary layer. In particular, horizontal gradients in sensible heat flux can induce convergence zones which favour the initiation of deep convection. A recent study based on satellite data (Taylor et al. Nature Geoscience 2011), illustrated the climatological importance of soil moisture gradients in the initiation of long-lived Mesoscale Convective Systems (MCS) in the Sahel. Here we explore the relationships between MCS life-cycles and the underlying surface using a unique convection-permitting simulation over West Africa during the wet season. Under the UK CASCADE project, the Met Office Unified Model was run with a grid length of 4km over a domain of 4000 x 3000 km for the period 25th July to 2nd September 2006. Over the course of the integration, the model generates a large population of MCS to analyse, each creating new soil moisture structures which in turn can feed back on the atmosphere. We track simulated MCS developing in varied environments and examine how land surface features influence convective initiation. We find strong consistency between the previous analysis of satellite data and the model. Specifically, the model captures the observed preference for convective initiation close to strong soil moisture gradients, with storms developing on the upwind side of transitions from dry to wet soil. The model clearly illustrates the pre-storm surface-induced circulation previously hypothesised to be responsible for the land-atmosphere coupling.

Taylor, Christopher; Birch, Cathryn; Dixon, Nick; Parker, Douglas

2013-04-01

406

Occurrence rate of extreme magnetic storms  

E-print Network

Statistical analysis of occurrence rate of magnetic storms induced by different types of interplanetary drivers is made on the basis of OMNI data for period 1976-2000. Using our catalog of large scale types of solar wind streams we study storms induced by interplanetary coronal mass ejections (ICME) (separately magnetic clouds (MC) and Ejecta) and both types of compressed regions: corotating interaction regions (CIR) and Sheaths. For these types of drivers we calculate integral probabilities of storms with minimum Dst storms shows that such a magnetic storm as Carrington storm in 1859 with Dst = -1760 nT is observed on the Earth with frequency 1 event during ~500 year.

Yermolaev, Yu I; Nikolaeva, N S; Yermolaev, M Yu

2013-01-01

407

Electrification in winter storms and the analysis of thunderstorm overflight data  

NASA Technical Reports Server (NTRS)

We have been focusing our study of electrification in winter storms on the lightning initiation process, making inferences about the magnitude of the electric fields from the initial pulses associated with breakdown, i.e., with the formation of the initial streamers. The essence of the most significant finding is as follows: (1) initial breakdown radiation pulses from stepped leaders prior to the first return stroke are very large, reaching values of 20-30 Volts/meter, comparable to return stroke radiation; and (2) the duration of the stepped leader, from the initial detectable radiation pulse to the return stroke onset, is very-short-ranging from a minimum 1.5 ms to a maximum of 4.5 ms. This past summer (June-August of 1991) we participated in the CAPE program at the Kennedy Space Center in order to acquire data on stepped leaders in summer storms with the same equipment used to get the winter storm data. We discovered that the vigorous leaders seen in winter so frequently were present in summer storms, although not as large in amplitude and certainly not as frequent.

Brook, Marx

1993-01-01

408

Electrodynamics of the inner magnetosphere observed in the dusk sector by CRRES and DMSP during the magnetic storm of June 4 – 6, 1991  

Microsoft Academic Search

We compare equatorward\\/earthward boundaries of convection electric fields and auroral\\/plasma sheet electrons detected by the DMSP F8 and CRRES satellites during the June 1991 magnetic storm. Measurements come from the dusk magnetic local time sector where the ring current penetrates closest to the Earth. The storm was triggered by a rapid increase in the solar wind dynamic pressure accompanied by

W. J. Burke; N. C. Maynard; M. P. Hagan; R. A. Wolf; G. R. Wilson; L. C. Gentile; M. S. Gussenhoven; C. Y. Huang; T. W. Garner; F. J. Rich

1998-01-01

409

Auroral currents during the magnetic storm of November 8 and 9, 1991 - Observations from the Upper Atmosphere Research Satellite Particle Environment Monitor  

NASA Technical Reports Server (NTRS)

The development of the intensity and location of Birkeland currents associated with the magnetic storm of November 8-9, 1991 is reported. Total Birkeland currents exceed 30 MA, more than six times nominal values, indicating Joule heating of about 3 x lO exp 12 W. Birkeland currents below 50 deg, polar cap currents indicative of antisunward convection, and cusp particle signatures of southward IMF all persist at least eight hours into recovery phase of the storm.

Anderson, B. J.; Potemra, T. A.; Bythrow, P. F.; Zanetti, L. J.; Holland, D. B.; Winningham, J. D.

1993-01-01

410

Computer simulation of inner magnetospheric dynamics for the magnetic storm of July 29, 1977  

Microsoft Academic Search

We present preliminary results of applying the Rice convection model to the early main phase of the magnetic storm of July 29, 1977. The computer model self-consistently computes electric fields and currents, as well as plasma distributions and velocities, in the inner-magnetosphere\\/ionosphere system. In the equatorial plane, the region modeled includes geocentric distances less than about the magnetopause standoff distance.

R. A. Wolf; M. Harel; R. W. Spiro; G.-H. Voigt; P. H. Reiff; C.-K. Chen

1982-01-01

411

A summary of research on mesoscale energetics of severe storm environments  

NASA Technical Reports Server (NTRS)

The goals of this research were to better understand interactions between areas of intense convection and their surrounding mesoscale environments by using diagnostic budgets of kinetic (KE) and available potential energy (APE). Three cases of intense convection were examined in detail. 1) Atmospheric Variability Experiments (AVE) carried out on 24 to 25 April 1975 were studied. Synoptic scale data at 3 to 6 hour intervals, contained two mesoscale convective complexes (MCCs). Analyses included total KE budgets and budgets of divergent and rotational components of KE. 2) AVE-Severe Environmental Storms and Mesoscale Experiments (SESAME)-4 carried out on 10 to 11 April 1979 were studied. Synotpic and meso alpha-scale data (250 km spacing, 3 hour intervals), contained the Red River Valley tornado outbreak. Analyses included total KE budgets (separate synoptic and mesoscale version), budgets for the divergent and rotational components, and the generation of APE by diabatic processes. 3) AVE-SESAME 5 studies were carried out on 20 to 31 May 1979. Synoptic and meso beta-scale data (75 km spacing, 1 1/2 to 3 hour intervals), contained a small MCC. Analyses include separate KE budgets for the synotic and meso beta-scales and a water vapor budget. Major findings of these investigations are: (1) The synoptic scale storm environment contains energy conversions and transports that are comparable to those of mature midlatitude cyclones. (2) Energetic in the mesoscale storm environment are often an order of magnitude larger than those in an undisturbed region. (3) Mesoscale wind maxima form in the upper troposphere on the poleward sides of convective areas, whereas speeds decrease south of storm regions.

Fuelberg, H. E.

1985-01-01

412

Springtime North Polar Dust Storms  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-321, 12 December 2002

As on the Earth, many severe storms brew in the martian polar regions. Here, temperature contrasts between the cold carbon dioxide ('dry ice') seasonal frost cap and the warm ground adjacent to it--combined with a flow of cool polar air evaporating off the cap--sweeps up dust and funnels it into swirling dust storms along the cap edge. The dust storms shown here were observed during the recent northern spring by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in May 2002. The picture is a mosaic of daily global images from the MOC wide angle cameras. The north polar cap is the bright, frosty surface at the top.

2002-01-01

413

Areal coverage of storm precipitation  

NASA Technical Reports Server (NTRS)

The probability distributions of the spatial distribution of precipitation from storms of different types were studied. The occurrence of wetted rainstorm area within a catchment was modeled as a Poisson arrival process in which each storm is composed of stationary, nonoverlapping, independent random cell clusters whose centers are Poisson-distributed as through fractals. The portion of a catchment covered by a stationary rainstorm was modeled by the common area of two overlapping circles. The first two moments of the distribution of the common area were derived from purely geometrical considerations. The spatial structure of the depth of rainfall from a stationary rainstorm was investigated using point process techniques. Total storm rainfall at the center of each cell is a random variable, and rainfall is distributed around the center specified by a spread function that may incorporate random parameters.

Eagleson, P. S.

1985-01-01

414

Severe storm initiation and development from satellite infrared imagery and Rawinsonde data  

NASA Technical Reports Server (NTRS)

The geographical distribution of potential temperatures, mixing ratio, and streamlines of flow patterns at 850, 700, and 500 mb heights are used to understand the prestorm convection and the horizontal convergence of moisture. From the analysis of 21 tornadoes the following conclusions are reached: (1) Strong horizontal convergence of moisture appeared at the 850, 700, and 500 mb levels in the area 12 hours before the storm formation; (2) An abundantly moist atmosphere below 3 km (700 mb) becomes convectively unstable during the time period between 12 and 24 hours before the initiation of the severe storms; (3) Strong winds veering with height with direction parallel to the movement of a dryline, surface fronts, etc; (4) During a 36-hour period, a tropopause height in the areas of interest is lowest at the time of tornadic cloud formation; (5) A train of gravity waves is detected before and during the cloud formation period. Rapid-scan infrared imagery provides near real-time information on the life cycle of the storm which can be summarized as follows: (1) Enhanced convection produced an overshooting cloud top penetrating above the tropopause, making the mass density of the overshooting cloud much greater than the mass density of the surrounding air; (2) The overshooting cloud top collapsed at the end of the mature stage of the cloud development; (3) The tornado touchdown followed the collapse of the overshooting cloud top.

Hung, R. J.; Smith, R. E.; West, G. S.

1984-01-01

415

Multi-Sensor Analysis of Overshooting Tops in Tornadic Storms  

NASA Astrophysics Data System (ADS)

The disastrous 2011 tornado season focused much attention on the ~75% false alarm rate for NWS-issued tornado warnings. Warnings are correctly issued on ~80% of verified tornados, but the false alarm rate has plateaued at near 75%. Any additional clues that may signal tornadogenesis would be of great benefit to the public welfare. We have performed statistical analyses of the structure and time-evolution of convective overshooting tops for tornadic storms occurring in the continental United States since 2006. An amalgam of case studies and theory has long suggested that overshooting tops may often collapse just prior to the onset of tornado touchdown. Our new results suggest that this view is supported by a broad set of new statistical evidence. Our approach to the analysis makes use of a high resolution, multi-sensor data set, and seeks to gather statistics on a large set of storms. Records of 88-D NEXRAD radar Enhanced-Resolution Echo Tops (product available since 2009) have been analyzed for an hour prior to and following touchdown of all EF1 and stronger storms. In addition, a coincidence search has been performed for the NASA A-Train satellite suite and tornadic events since 2006. Although the paths of the polar-orbiting satellites do not aid in analyses of temporal storm-top evolution, Aqua-MODIS, CALIPSO, and Cloud-Sat have provided a detailed structural picture of overshooting tops in tornadic and non-tornadic supercell thunderstorms. 250 m resolution AQUA-MODIS image at 1950Z on 4/27/2011, color-enhanced to emphasize overshooting tops during tornado outbreak.

Magee, N. B.; Goldberg, R.; Hartline, M.

2012-12-01

416

Bracing for the geomagnetic storms  

SciTech Connect

The authors discuss the impact of geomagnetic storms on utility transmission networks. The effects of a recent storm on the Hydro-Quebec transmission system are described in detail. Research into geomagnetic disturbance prediction is discussed. In coming months, geomagnetic field activity will be high as it builds toward a peak, the 22nd since reliable records of the phenomenon began in the mid-1700s. The peaks come in roughly 11-year cycles, and the next is expected later this year or early in 1991. The solar activity has so far risen at one of the fastest rates ever recorded, and solar forecasters expect cycle 22 to have unusually high activity levels.

Kappenman, J.G. (Minnesota Power, Duluth, MN (US)); Albertson, V.D. (Univ. of Minnesota, Dept. of Electrical Engineering, Minneapolis, MN (US))

1990-03-01

417

National Severe Storms Forecast Center  

NASA Technical Reports Server (NTRS)

The principal mission of the National Severe Storms Forecast Center (NSSFC) is to maintain a continuous watch of weather developments that are capable of producing severe local storms, including tornadoes, and to prepare and issue messages designated as either Weather Outlooks or Tornado or Severe Thunderstorm Watches for dissemination to the public and aviation services. In addition to its assigned responsibility at the national level, the NSSFC is involved in a number of programs at the regional and local levels. Subsequent subsections and paragraphs describe the NSSFC, its users, inputs, outputs, interfaces, capabilities, workload, problem areas, and future plans in more detail.

1977-01-01

418

Global simulation of EMIC wave excitation during the 21 April 2001 storm from coupled RCM-RAM-HOTRAY modeling  

NASA Astrophysics Data System (ADS)

The global distribution and spectral properties of electromagnetic ion cyclotron (EMIC) waves in the He+ band are simulated for the 21 April 2001 storm using a combination of three different codes: the Rice Convection Model, the Ring current-Atmospheric interactions Model, and the HOTRAY ray tracing code (incorporated with growth rate solver). During the storm main phase, injected ions exhibit a non-Maxwellian distribution with pronounced phase space density minima at energies around a few keV. Ring current H+ injected from the plasma sheet provides the source of free energy for EMIC excitation during the storm. Significant wave gain is confined to a limited spatial region inside the storm time plume and maximizes at the eastward edge of the plume in the dusk and premidnight sector. The excited waves are also able to resonate and scatter relativistic electrons, but the minimum electron resonant energy is generally above 3 MeV.

Chen, Lunjin; Thorne, Richard M.; Jordanova, Vania K.; Wang, Chih-Ping; Gkioulidou, Matina; Lyons, Larry; Horne, Richard B.

2010-07-01

419

Military Review: Desert Shield/Desert Storm.  

National Technical Information Service (NTIS)

CONTENTS: CASCOM Support for DESERT SHIELD/DESERT STORM; Total Army CSS: Providing the Means for Victory; Logistics Automation Support for Desert Storm; Building the DESERT Logistics force; Depot operations Supporting DESERT SHIELD; The Readiness Group's ...

1991-01-01

420

Satellite View of 2 Trop. Storms  

NASA Video Gallery

System 98L exploded into Tropical Storm Irene on Saturday, August 20. This GOES-13 Video shows Tropical Storm Harvey making landfall in Belize (just beneath the Yucatan Peninsula) and moving into t...

421

Tropical Storm Debby Moves into Atlantic  

NASA Video Gallery

An animation of satellite observations shows the progression of Tropical Storm Debby from June 25-27, 2012. The animation shows that Tropical Storm Debby's center move from the northeastern Gulf of...

422

Coastal processes: Storm-proofing with marshes  

NASA Astrophysics Data System (ADS)

Shorelines are vulnerable to the destructive waves and water levels of increasingly frequent extreme storm events. Wave tank experiments demonstrate that salt marsh vegetation dissipates wave energy and withstands extreme storm conditions.

Fagherazzi, Sergio

2014-10-01

423

A composite study of onset of the Australian summer monsoon  

NASA Technical Reports Server (NTRS)

The circulation changes that accompany an onset (defined as the first occurrence of wet 850-mb westerly winds at Darwin, Australia) of the Australian summer monsoon are documented by a composite study for the years 1957-1987. Composites of atmospheric fields at stations in and about the Australian tropics are constructed relative to the onset data at Darwin. It is shown that the composite onset is dominated by a slow eastward migration of a deep-baroclinic convective circulation displaced south of the equator. This propagating anomaly exhibited many features of the so-called 40-50 day oscillation, including an upper level anticyclone that accompanies the convective anomaly.

Hendon, Harry H.; Liebmann, Brant

1990-01-01

424

Summer English Language Program Summer 2014  

E-print Network

Niagara Falls, attending Major League Baseball games and hiking around many of the beautiful local parks, center) #12;CAMpus LIfe Meals a meal card is included in tuition fees, which entitles students attending the Summer eSl Program will be given a MacID to have full access to library and computer

Hitchcock, Adam P.

425

Mesoscale aspects of storms producing floods over regions of arid mountainous terrain  

NASA Astrophysics Data System (ADS)

We have used the TRMM satellite's Precipitation Radar (PR) to develop a climatology of extreme convection in the regions of the Andes and Himalayas. This work shows that intense convection often occurs in arid regions but does not usually produce large amounts of rain. Large quantities of rain falling in mountainous regions is associated with the convective systems that have the greatest horizontal scales. When such wide systems occur over arid mountains, they can produce lethal floods. The Pakistan flood of 2010 is a case in point. Wide convective systems with large stratiform components became situated over the arid mountains of that region, with the result of the Indus River overflowed with disastrous consequences over a huge area. The potential of heavy rain in the region could have been inferred from the forecast synoptic-scale circulation, which indicated the occurrence of a great buildup of moisture in the region. Although the synoptic conditions were well forecast, that information alone was insufficient for predicting the flood conditions. It would have been necessary to anticipate also the mesoscale structure of the storms. Our TRMM satellite climatology of rainstorm structures in this region indicated that the mesoscale convective rainstorms responsible for the floods were of a type that does not normally occur in this region. Rather, this type of storm usually occurs and produces copious monsoon rain far to the east, over the mountains and wetlands of northeastern India and Bangladesh. In this event, catastrophic runoff and flooding resulted as these rainstorms occurred far to the west of where they usually occur, over an arid and mountainous region unaccustomed to such storms. This study indicates that taking into account the mesoscale structures of the cloud systems as well as the synoptic conditions in which they are embedded is essential for forecasting floods in this region of complex terrain.

Houze, R.; Romatschke, U.; Rasmussen, K. L.

2011-12-01

426

Summer by the Book  

NSDL National Science Digital Library

Are you looking for ways to log professional development hours without traveling too far away from home this summer? Through reading, a teacher can spend valuable hours updating content backg