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Sample records for summer convective storms

  1. Mesoscale aspects of convective storms

    NASA Technical Reports Server (NTRS)

    Fujita, T. T.

    1981-01-01

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

  2. Convective storms in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Sánchez-Lavega, A.

    2013-05-01

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

  3. Towards an offline parameterization of convective dust storms

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  4. Interactions Between Convective Storms and Their Environment

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Sánchez-Lavega, A.

    2005-08-01

    The arrival of the Cassini/Huygens mission to Titan has opened an unprecedented opportunity to study the atmosphere of this satellite. Under the pressure-temperature conditions on Titan, methane, a large atmospheric component amounting perhaps to a 3-5% of the atmosphere, is close to its triple point, potentially playing a similar role as water on Earth. The Huygens probe has shown a terrain shaped by erosion of probably liquid origin, suggestive of past rain. On the other hand, Voyager IRIS spectroscopic observations of Titan imply a saturated atmosphere of methane (amounting perhaps to 150 covered by methane clouds, if we think on Earth meteorology. However, observations from Earth and Cassini have shown that clouds are localized, transient and fast evolving, in particular in the South Pole (currently in its summer season). This might imply a lack of widespread presence on Titan of nuclei where methane could initiate condensation and particle growth with subsequent precipitation. We investigate different scenarios of moist convective storms on Titan using a complete 3D atmospheric model that incorporates a full microphysics treatment required to study cloud formation processes under a saturated atmosphere with low concentration of condensation nuclei. We study local convective development under a variety of atmospheric conditions: sub-saturation, super-saturation, abundances of condensation nuclei fall, condensation nuclei lifted from the ground or gently falling from the stratosphere. We show that under the appropriate circumstances, precipitation rates comparable to typical tropical storms on Earth can be found. Acknowledgements: This work has been funded by Spanish MCYT PNAYA2003-03216, fondos FEDER and Grupos UPV 15946/2004. R. Hueso acknowledges a post-doc fellowship from Gobierno Vasco.

  6. Moist convective storms in the atmosphere of Saturn

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Sánchez-Lavega, A.

    2003-05-01

    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 Equatorial region. However, Saturn seems to be very much less convective than Jupiter, being convective storms rare and small for the most part of the cases. Here we present simulations of moist convective storms in the atmosphere of Saturn at different latitudes, the Equator and 42 deg S, the regions where most of the convective activity of the planet has been observed. We use a 3D anelastic model of the atmosphere with parameterized microphysics (Hueso and Sánchez-Lavega, 2001) and we study the onset and evolution of moist convective storms. Ammonia storms are able to develop only if the static stability of the upper atmosphere is slightly decreased. Water storms are difficult to develop requiring very specific atmospheric conditions. However, when they develop they can be very energetic arriving at least to the 150 mbar level. The Coriolis forces play a mayor role in the characteristics of water based storms in the atmosphere of Saturn. The 3-D Coriolis forces at the Equator transfer upward momentum to westward motions acting to diminish the strength of the equatorial jet. The GWS of 1990 could have been a mayor force in reducing the intensity of the equatorial jet stream as revealed recently (Sánchez-Lavega et al. Nature, 2003). The Cassini spacecraft will arrive to Saturn in a year. Its observations of the atmosphere will allow to measure the amount of convective activity on the planet, its characteristics and it will clarify the role of moist convection in the atmospheric dynamics of the Giant Planets. Acknowledgements: This work was supported by the Spanish MCYT PNAYA 2000-0932. RH acknowledges a Post-doctoral fellowship from Gobierno Vasco.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  8. Observations of Florida Convective Storms Using Dual Wavelength Airborne Radar

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

  9. Late-summer Martian Dust Storm

    NASA Technical Reports Server (NTRS)

    2008-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Zuluaga, M. D.; Houze, R.

    2013-12-01

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

  11. Three unconventional airborne radar clues to severe convective storms

    NASA Astrophysics Data System (ADS)

    Trammell, Archie

    1989-01-01

    Even the most experienced commercial aircraft pilots have been found either to not possess the radar-operating and -interpreting skills required to differentiate between ground and weather echoes, or to possess such skills but no confidence in the ability of airborne radar to warn them of hazardous convective storms. It is presently noted that a radar reflectivity greater than 50 dbz, which corresponds to a rainfall rate of more than 4 inches/hr, will likely present the pilot with problems reflected in convective weather accident statistics; 9 out of 10 such accidents have occurred at rainfall rates approaching or exceeding 4 inches/hr.

  12. Nonlinear Stefan problem with convective boundary condition in Storm's materials

    NASA Astrophysics Data System (ADS)

    Briozzo, Adriana C.; Natale, Maria F.

    2016-04-01

    We consider a nonlinear one-dimensional Stefan problem for a semi-infinite material x > 0, with phase change temperature T f . We assume that the heat capacity and the thermal conductivity satisfy a Storm's condition, and we assume a convective boundary condition at the fixed face x = 0. A unique explicit solution of similarity type is obtained. Moreover, asymptotic behavior of the solution when {h→ + ∞} is studied.

  13. A-Train Observations of Deep Convective Storm Tops

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

  14. Modes of isolated, severe convective storm formation along the dryline

    SciTech Connect

    Bluestein, H.B.; Parker, S.S. )

    1993-05-01

    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 of the radar echoes evolved into isolated storms as isolated cells from the start; others developed either from a pair of cells, from a line segment, from a cluster of cells, from the merger of mature cells, or from a squall line. Proximity soundings were constructed from both standard and special soundings, and from standard surface data. It was found that the estimated convective available potential energy and vertical shear are characteristic of the environment of supercell storms. The average time lag between the first echo and the first occurrence of severe weather of any type, or tornadoes alone, was approximately 2 h. There were no significant differences in the environmental parameters for the different modes of storm formation. 49 refs., 15 figs., 3 tabs.

  15. Observations of Florida Convective Storms using Dual Wavelength Airborne Radar

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

  16. Spatial and diurnal variations of storm heights in the East Asia summer monsoon: storm height regimes and large-scale diurnal modulation

    NASA Astrophysics Data System (ADS)

    Park, Myung-Sook; Lee, Myong-In; Kim, Hyerim; Im, Jungho; Yoo, Jung-Moon

    2016-02-01

    This study investigates the spatial and diurnal variation of storm height in the East Asia summer monsoon region using 13-year Tropical Rainfall Measuring Mission Precipitation Radar data. Precipitating storms are classified as shallow (<5 km), middle (5-10 km), and deep (>10 km) depending the height. Four different regimes are identified to characterize the region: the continental (CT) shallow regime over inland China with elevated terrain, the CT deep over the Chinese Plain, the coastal (CS) middle over the East China Sea and South Sea of Korea, and the CS shallow over the south coastal area of Japan. This regime separation reflects well the distinctive regional difference in the rainfall contribution by each storm type. The occurrence frequencies of shallow, middle, and deep storms exhibit pronounced diurnal variation as well, but with significant differences in the amplitude and phase across the regimes. These lead to a diversity in the diurnal variation of surface rainfall such as bimodal morning and late evening peaks in the two CT regimes and the single morning peak in the two CS regimes. Processes involved in the diurnal variation of storms are different across the regimes, indicating difference in the contributing role of surface heating, large-scale diurnal circulation, and diurnal propagations of convective systems. The storm height also affects the rain intensity. This study highlights that the East Asia summer monsoon has distinctive sub-regional variation of the storm height distribution, thereby providing unique differences in the rainfall amount, intensity, and the diurnal variation.

  17. Summer rainfall over the southwestern Tibetan Plateau controlled by deep convection over the Indian subcontinent

    NASA Astrophysics Data System (ADS)

    Dong, Wenhao; Lin, Yanluan; Wright, Jonathon S.; Ming, Yi; Xie, Yuanyu; Wang, Bin; Luo, Yong; Huang, Wenyu; Huang, Jianbin; Wang, Lei; Tian, Lide; Peng, Yiran; Xu, Fanghua

    2016-03-01

    Despite the importance of precipitation and moisture transport over the Tibetan Plateau for glacier mass balance, river runoff and local ecology, changes in these quantities remain highly uncertain and poorly understood. Here we use observational data and model simulations to explore the close relationship between summer rainfall variability over the southwestern Tibetan Plateau (SWTP) and that over central-eastern India (CEI), which exists despite the separation of these two regions by the Himalayas. We show that this relationship is maintained primarily by `up-and-over' moisture transport, in which hydrometeors and moisture are lifted by convective storms over CEI and the Himalayan foothills and then swept over the SWTP by the mid-tropospheric circulation, rather than by upslope flow over the Himalayas. Sensitivity simulations confirm the importance of up-and-over transport at event scales, and an objective storm classification indicates that this pathway accounts for approximately half of total summer rainfall over the SWTP.

  18. Summer rainfall over the southwestern Tibetan Plateau controlled by deep convection over the Indian subcontinent.

    PubMed

    Dong, Wenhao; Lin, Yanluan; Wright, Jonathon S; Ming, Yi; Xie, Yuanyu; Wang, Bin; Luo, Yong; Huang, Wenyu; Huang, Jianbin; Wang, Lei; Tian, Lide; Peng, Yiran; Xu, Fanghua

    2016-01-01

    Despite the importance of precipitation and moisture transport over the Tibetan Plateau for glacier mass balance, river runoff and local ecology, changes in these quantities remain highly uncertain and poorly understood. Here we use observational data and model simulations to explore the close relationship between summer rainfall variability over the southwestern Tibetan Plateau (SWTP) and that over central-eastern India (CEI), which exists despite the separation of these two regions by the Himalayas. We show that this relationship is maintained primarily by 'up-and-over' moisture transport, in which hydrometeors and moisture are lifted by convective storms over CEI and the Himalayan foothills and then swept over the SWTP by the mid-tropospheric circulation, rather than by upslope flow over the Himalayas. Sensitivity simulations confirm the importance of up-and-over transport at event scales, and an objective storm classification indicates that this pathway accounts for approximately half of total summer rainfall over the SWTP. PMID:26948491

  19. Summer rainfall over the southwestern Tibetan Plateau controlled by deep convection over the Indian subcontinent

    PubMed Central

    Dong, Wenhao; Lin, Yanluan; Wright, Jonathon S.; Ming, Yi; Xie, Yuanyu; Wang, Bin; Luo, Yong; Huang, Wenyu; Huang, Jianbin; Wang, Lei; Tian, Lide; Peng, Yiran; Xu, Fanghua

    2016-01-01

    Despite the importance of precipitation and moisture transport over the Tibetan Plateau for glacier mass balance, river runoff and local ecology, changes in these quantities remain highly uncertain and poorly understood. Here we use observational data and model simulations to explore the close relationship between summer rainfall variability over the southwestern Tibetan Plateau (SWTP) and that over central-eastern India (CEI), which exists despite the separation of these two regions by the Himalayas. We show that this relationship is maintained primarily by ‘up-and-over' moisture transport, in which hydrometeors and moisture are lifted by convective storms over CEI and the Himalayan foothills and then swept over the SWTP by the mid-tropospheric circulation, rather than by upslope flow over the Himalayas. Sensitivity simulations confirm the importance of up-and-over transport at event scales, and an objective storm classification indicates that this pathway accounts for approximately half of total summer rainfall over the SWTP. PMID:26948491

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

    NASA Astrophysics Data System (ADS)

    Grinn-Gofroń, Agnieszka; Strzelczak, Agnieszka

    2013-09-01

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

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

    PubMed

    Grinn-Gofroń, Agnieszka; Strzelczak, Agnieszka

    2013-09-01

    Fungal spores are known to cause allergic sensitization. Recent studies reported a strong association between asthma symptoms and thunderstorms that could be explained by an increase in airborne fungal spore concentrations. Just before and during thunderstorms the values of meteorological parameters rapidly change. Therefore, the goal of this study was to create a predictive model for hourly concentrations of atmospheric Alternaria and Cladosporium spores on days with summer storms in Szczecin (Poland) based on meteorological conditions. For this study we have chosen all days of June, July and August (2004-2009) with convective thunderstorms. There were statistically significant relationships between spore concentration and meteorological parameters: positive for air temperature and ozone content while negative for relative humidity. In general, before a thunderstorm, air temperature and ozone concentration increased, which was accompanied by a considerable increase in spore concentration. During and after a storm, relative humidity increased while both air temperature ozone concentration along with spore concentrations decreased. Artificial neural networks (ANN) were used to assess forecasting possibilities. Good performance of ANN models in this study suggest that it is possible to predict spore concentrations from meteorological variables 2 h in advance and, thus, warn people with spore-related asthma symptoms about the increasing abundance of airborne fungi on days with storms. PMID:23161270

  2. Transport of Formaldehyde to the Upper Troposphere In Deep Convective Storms During the 2012 DC3 Study

    NASA Astrophysics Data System (ADS)

    Fried, A.; Weibring, P.; Richter, D.; Walega, J.; Olson, J. R.; Crawford, J. H.; Barth, M. C.; Apel, E. C.; Hornbrook, R. S.; Bela, M. M.; Toon, O. B.; Blake, D. R.; Blake, N. J.; Luo, Z. J.

    2014-12-01

    The Deep Convective Clouds and Chemistry (DC3) campaign in the summer of 2012 provided an opportunity to study the impacts of deep convection on reactive and soluble precursors of ozone and HOx radicals, including CH2O, in the upper troposphere and lower stratosphere (UTLS) over North America. Formaldehyde measurements were acquired in the inflow and outflow of numerous storms on the NASA DC-8 and NSF/NCAR GV-aircraft employing fast, sensitive, and accurate difference frequency generation infrared absorption spectrometers. Since our Fall 2013 AGU Meeting poster, we have developed an improved methodology based upon 3 independent approaches, to determine the amount of CH2O that is scavenged by deep convective storms. The first approach is based upon WRF-Chem model simulations, which provides greater confidence in the determination of CH2O scavenging efficiencies and allows the estimation of CH2O ice retention factors.The second approach is a modified mixing model employing 4 non-reactive passive tracers (n,i-butane, n,i-pentane) to estimate altitude-dependent lateral entrainment rates. This information is coupled with time-dependent measurements in the outflow of various storms, which when extrapolated to time zero in the storm core, results in estimates of CH2O scavenging efficiencies. This analysis includes estimates of photochemically produced CH2O in the storm core. A third approach is based upon CH2O/n-butane ratio comparisons in both the storm inflow and outflow. Results from various storms over Oklahoma, Colorado, and Alabama will be presented. However, the analysis will primarily focus on the May 29, 2012 supercell storm in Oklahoma. During this storm, the 4 passive tracers produced a very consistent lateral entrainment rate of 0.083 ± 0.008 km-1, a value that broadly agrees with entrainment rates determined previously from analyzing moist static energy profiles (Luo et al., Geophys. Res. Lett., 2010). For this storm, the 3-independent approaches give CH2O scavenging efficiencies in the 49-55% range. Although somewhat higher than previous determinations, there is still sufficient transport of CH2O to the UTLS, thus providing an important source to the HOx budget in convective outflow regions.

  3. Numerical modeling of severe convective storms occurring in the Carpathian Basin

    NASA Astrophysics Data System (ADS)

    Horvth, .; Geresdi, I.; Nmeth, P.; Csirmaz, K.; Dombai, F.

    Squall lines often cause serious damages due to the strong surface outflow, hail, or heavy precipitation in Hungary every summer. Squall lines in the Carpathian Basin can be classified into two main categories: pre-frontal squall-lines and frontal convective lines. In this paper, these two types of severe mesoscale phenomena are investigated using the high resolution numerical weather prediction model, the MM5. The case study for the first type of convective systems occurred on 18th May 2005 when two main convective lines with their embedded severe storms formed daytime and caused high-velocity wind events and extensive damages in the eastern part of Hungary. The second case study is a frontal squall line that hit Budapest on 20th August 2006 and the associated high precipitation (HP) supercells reached the capital of Hungary at same time when the traditional Constitution Day firework began. The consequences were catastrophic: five people were killed and more than one thousand were injured due to the extreme weather. The non-hydrostatic high resolution MM5 model was able to simulate and catch the severe weather events occurred on the days under discussion. Moreover, the model was able to compute the detailed structure of the supercells embedded in thunderstorm lines. By studying the equivalent potential temperature (EPT) fields at lower levels, we state that in the prefrontal case, there is a competition between the supercell thunderstorms for the wet and warm air. A thunderstorm that can collect the wet and warm air from larger area will have longer lifetime and more intense updraft. In the second case, the frontal squall lines, the movement and the behavior of the supercell storms embedded in the line was highly determined by the synoptic-scale motions and less affected by the EPT field of the prefrontal masses.

  4. Using Satellite Observation for Early Warning of Convective Storm in Tehran

    NASA Astrophysics Data System (ADS)

    Owlad, E.

    2015-12-01

    Severe convective storms are responsible for large amount of damage each year around the world. They form an important part of the climate system by redistributing heat, moisture, and trace gases, as well as producing large quantities of precipitation. As these extreme and rare events are in mesoscale there is many uncertainty in predicting them and we can't rely on just models. On the other hand, remote sensing has a large application in Meteorology and near real time weather forecasting, especially in rare and extreme events like convective storms that might be difficult to predict with atmospheric models. On second of June 2014, near 12UTC a sudden and strong convective storm occurred in Tehran province that was not predicted, and caused economic and human losses. In This research we used satellite observations along with synoptic station measurements to predict and monitor this storm. Results from MODIS data show an increase in the amount of cloudiness and also aerosol optical depth and sudden decrease in cloud top temperature few hours before the storm occurs. EUMETSAT images show the governing of convection before the storm occurs. With combining the observation data that shows Lake of humidity and high temperature in low levels with satellite data that reveals instability in high levels that together caused this convective, we could track the storm and decrease the large amount of damage.

  5. Observed and Simulated Radiative and Microphysical Properties of Tropical Convective Storms

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  6. Convective rain rates and their evolution during storms in a semiarid climate

    NASA Technical Reports Server (NTRS)

    Doneaud, A. A.; Miller, J. R., Jr.; Ionescu-Niscov, S.

    1984-01-01

    The semiarid climate of the U.S. northern High Plains region has been studied with respect to rain rates and their evolution during summertime convective storms, using radar data from a total of 750 radar echo clusters. Analysis of this data suggests that the average rain rate R among storms is in a first approximation independent of the total rain volume, if the entire storm duration is considered in the averaging process. R primarily depends on the reflectivity threshold considered in calculating the area coverage integrated over the lifetime of the storm. R evolution during storms is analyzed by dividing each storm lifetime into 10 min, 1, 2, and 4 hours, as well as growing and decaying periods. The value of R remained independent of the total rain volume when the growing or decaying periods of storms were considered separately.

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

    NASA Astrophysics Data System (ADS)

    Li, C.; Ingersoll, A. P.

    2012-12-01

    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.

  8. Growth Of The Summer Daytime Convective Boundary Layer At Anand

    NASA Astrophysics Data System (ADS)

    Nagar, S. G.; Tyagi, Ajit; Seetaramayya, P.; et al.

    The heights of the daytime convective boundary layer (CBL), computed by a one-dimensional model for a bare soil surface at a semi-arid station,Anand, during the dry and hot summer month of May 1997, are presented. As input, the model requires surface heat flux, friction velocity and air temperature as functions of time. Temperature data at the one-metre level from a tower and sonic anemometer data at 9.5 m collected during the period 13-17 May 1997 in the Land Surface Processes Experiment (LASPEX-97) are used to compute hourly values of surface heat flux, friction velocity and Obukhov length following the operational method suggested by Holtslag and Van Ulden [J. Climate Appl. Meteorol. 22,517-529 (1983)]. The model has been tested with different values for the potential temperature gradient ( ) above the inversion. The model-estimated CBL heights comparefavourably with observed heights obtained from radiosonde ascents.

  9. Moist convection in hydrogen atmospheres and the frequency of Saturn’s giant storms

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Ingersoll, Andrew P.

    2015-05-01

    A giant storm erupted on Saturn in December 2010. It produced intense lightning and cloud disturbances and encircled the planet in six months. Six giant storms--also called Great White Spots--have been observed on Saturn since 1876, recurring every 20 to 30 years and alternating between mid-latitudes and the equator. Here we use thermodynamic arguments to demonstrate that the quasi-periodic occurrence of Saturn’s giant storms can be explained by a water-loading mechanism, in which moist convection is suppressed for decades owing to the relatively large molecular weight of water in a hydrogen-helium atmosphere. We find that the interaction between moist convection and radiative cooling in the troposphere above the cloud base produces an oscillation that leads to giant storm generation with a period of approximately 60 years for either mid-latitudes or the equator, provided the mixing ratio of water vapour in the troposphere exceeds 1.0%. We use a two-dimensional axisymmetric dynamic model and a top-cooling convective adjustment scheme to apply our conceptual model to Saturn. For a water vapour mixing ratio of 1.1%, simulated storms show a recurrence interval, ammonia depletion and tropospheric warming that are consistent with 2010 observations. Jupiter’s atmosphere is more depleted in water than Saturn, which may explain its lack of planet-encircling storms.

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  11. Airborne Doppler Radar Observations of a Convective Storm.

    NASA Astrophysics Data System (ADS)

    Ray, Peter S.; Jorgensen, David P.; Wang, Sue-Lee

    1985-07-01

    Airborne Doppler radar can collect data on target storms that are quite widely dispersed. However, the relatively long time required to sample an individual storm in detail, particularly with a single aircraft, and the amplification of the statistical uncertainty in the radial velocity estimates when Cartesian wind components are derived, suggests that errors in wind fields derived from airborne Doppler radar measurements would exceed those from a ground based radar network which was better located to observe the same storm. Error distributions for two analysis methods (termed Overdetermined and Direct methods) are given and discussed for various flight configurations. Both methods are applied to data collected on a sea breeze induced storm that occurred in western Florida on 28 July 1982. Application of the direct solution, which does not use the continuity equation, and the overdetermined dual-Doppler method, which requires the use of the continuity equation, resulted in similar fields. Since the magnitude of all errors are unknown and the response of each method to errors is different, it is difficult to assess overall which analysis performs better; indeed each might be expected to perform best in different parts of the analysis domain. A flexible collection strategy can be followed with different analysis methods to optimize the quality of resulting synthesized wind fields.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  13. Isolating the response of Central US summer precipitation to anthropogenic climate change in global simulations with explicitly resolved convection

    NASA Astrophysics Data System (ADS)

    Kooperman, G. J.; Pritchard, M. S.; Somerville, R. C.

    2013-12-01

    Organized propagating storms, known as mesoscale convective systems (MCSs) bring nearly 60% of summer rainfall to the Central US but are not simulated by conventional global climate models (GCMs). GCMs that do not realistically represent the physical mechanisms that generate MCSs in nature cannot assess how they may respond to climate change, and as a result disagree on the sign of future US precipitation trends. Important questions remain highly uncertain: How will summer storms in the Central US respond to higher greenhouse gas concentrations? Will changes in the pattern or intensity of rain associated with these organized storms lead to more drought or flood conditions? A new GCM that apparently captures key aspects of MCS physics is one that simultaneously resolves small- and large-scale processes in an approach called super-parameterization (SP), which uses simplified cloud resolving models in place of conventional parameterizations. Here a new regional MCS index is developed to evaluate the signal in observations, and conventional- and super-parameterized versions of the NCAR Community Atmosphere Model (CAM). Analysis across three versions of SP-CAM (3.0, 3.5, and 5.0) show the emergence of nocturnal, eastward propagating convection is a robust feature of SP. Composite analysis reveals that the extent, intensity, and frequency of MCS events and resulting precipitation are most realistic in SP-CAM5.0. Climate change experiments (4x CO2) with SP-CAM5.0 suggest that future storms may become more intense with more liquid/ice condensate, greater areal extent, higher rainfall rate, and longer persistence.

  14. Submicron Aerosol Transport and Aging by Convective Storms During the DC3 Campaign

    NASA Astrophysics Data System (ADS)

    Campuzano Jost, P.; Day, D. A.; Palm, B. B.; Ortega, A. M.; Hayes, P. L.; Jimenez, J. L.

    2012-12-01

    The Deep Convective Clouds and Chemistry (DC3) study was a multiagency sponsored aircraft campaign to characterize the contribution of strong convective spring storms over the Midwestern US to the chemistry of the upper troposphere (UT), both by transport of pollutants from the boundary layer to the UT and by acting as a fast, multiphase chemical reactor. Over twenty research flights targeting storms in Eastern Colorado, Southern Oklahoma and Alabama as well as outflow from past storms in those regions were conducted out of Salina, KS using the NCAR/NSF G-V and the NASA DC-8 research aircraft. An Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-AMS) was deployed on board of the NASA DC-8 during DC3. Chemically speciated submicron aerosol mass concentrations were measured with 1 second time resolution. Size-resolved composition data were acquired with a lower frequency (~1 min). While overall, measured aerosol concentrations in the UT were very low and consistent with background sulfate, several stronger storms sampled during DC3 resulted in significant concentrations of (aged) organic and nitrate aerosols at altitudes >8 km. A detailed analysis of the concentration and chemical properties of the organic fraction of the aerosol in the storm inflow and UT aerosol is used to determine to what extent the aging signature is due to selective transport/deposition of particles from the boundary layer vs in-cloud formation and/or processing of those particles. A special case was the flight on Jun 22nd, 2012, when fresh smoke from the High Park Fire near Ft. Collins,CO was entrained into the updraft of a storm, resulting in organic UT loadings in excess of 50 ug/m3. Here it was again possible to sample the fresh smoke plume prior to entering the storm cloud and hence observe the chemical evolution of the smoke as it was lofted by the storm.

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  16. Role of magnetospheric convection and precipitation in the formation of the "dusk effect" during the main phase of a magnetic storm

    NASA Astrophysics Data System (ADS)

    Tashchilin, A. V.; Romanova, E. B.

    2011-08-01

    This paper studies the role of magnetospheric factors, such as convection and energetic electron precipitation during the formation of positive disturbances in the total electron content under the conditions of the summer evening ionosphere. À numerical model of the ionosphere and plasmasphere, where time variations in the magnetospheric convection velocity and electron precipitation parameters correspond to the main phase of a magnetic storm, has been used for this purpose. It has been indicated that the total electron content sharply increases (the "dusk effect") in the eastern and western sectors at approximately the same geomagnetic latitudes corresponding to the subauroral zone provided that a sudden storm commencement is registered in the morning hours. local time. This peak of the total electron content is formed as a result of joint reconstruction of the magnetospheric convection pattern and energetic electron precipitation during the main phase of a storm. In this case, magnetospheric convection plays the main role, raising the F2 layer by 40-80 km into the region with a lower recombination rate.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Nowotarski, Christopher J.

    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.

  19. The distribution of deep convection over ocean and land during the Asian summer monsoon

    NASA Technical Reports Server (NTRS)

    Grossman, Robert L.; Garcia, Oswaldo

    1990-01-01

    The characteristics of the convection over the summer monsoon are investigated using the highly reflective cloud (HRC) data set (which is a subjective-analyzed daily index of organized deep convection, at one degree resolution, for years between 1971 and 1988 of the polar-orbiting satellite imagery). The results of the analysis are used to obtain the geographical distribution of HRCs for the climatological mean summer monsoon season and its four component months and to examine the intraseasonal variation of convection over selected areas. The model results of Webster and Chou (1980) are tested by comparing the relative frequency of occurrence of HRC for continental areas, coastal zones, and open ocean.

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

    NASA Astrophysics Data System (ADS)

    Leuenberger, D.; Rossa, A.

    2007-12-01

    Next-generation, operational, high-resolution numerical weather prediction models require economical assimilation schemes for radar data. In the present study we evaluate and characterise the latent heat nudging (LHN) rainfall assimilation scheme within a meso-γ scale NWP model in the framework of identical twin simulations of an idealised supercell storm. Consideration is given to the model’s dynamical response to the forcing as well as to the sensitivity of the LHN scheme to uncertainty in the observations and the environment. The results indicate that the LHN scheme is well able to capture the dynamical structure and the right rainfall amount of the storm in a perfect environment. This holds true even in degraded environments but a number of important issues arise. In particular, changes in the low-level humidity field are found to affect mainly the precipitation amplitude during the assimilation with a fast adaptation of the storm to the system dynamics determined by the environment during the free forecast. A constant bias in the environmental wind field, on the other hand, has the potential to render a successful assimilation with the LHN scheme difficult, as the velocity of the forcing is not consistent with the system propagation speed determined by the wind. If the rainfall forcing moves too fast, the system propagation is supported and the assimilated storm and forecasts initialised therefrom develop properly. A too slow forcing, on the other hand, can decelerate the system and eventually disturb the system dynamics by decoupling the low-level moisture inflow from the main updrafts during the assimilation. This distortion is sustained in the free forecast. It has further been found that a sufficient temporal resolution of the rainfall input is crucial for the successful assimilation of a fast moving, coherent convective storm and that the LHN scheme, when applied to a convective storm, appears to necessitate a careful tuning.

  1. GOES 12 observations of convective storm variability and evolution during the Tropical Composition, Clouds and Climate Coupling Experiment field program

    NASA Astrophysics Data System (ADS)

    Bedka, Kristopher M.; Minnis, Patrick

    2010-05-01

    This study characterizes convective clouds that occurred during the Tropical Composition, Clouds and Climate Coupling Experiment as observed within GOES imagery. Overshooting deep convective cloud tops (OT) that penetrate through the tropical tropopause layer and into the stratosphere are of particular interest in this study. The results show that there were clear differences in the areal coverage of anvil cloud, deep convection, and OT activity over land and water and also throughout the diurnal cycle. The offshore waters of Panama, northwest Colombia, and El Salvador were the most active regions for OT-producing convection. A cloud object tracking system is used to monitor the duration and areal coverage of convective cloud complexes as well as the time evolution of their cloud-top microphysical properties. The mean lifetime for these complexes is 5 hours, with some existing for longer than 16 hours. Deep convection is found within the anvil cloud during 60% of the storm lifetime and covered 24% of the anvil cloud. The cloud-top height and optical depth at the storm core followed a reasonable pattern, with maximum values occurring 20% into the storm lifetime. The values in the surrounding anvil cloud peaked at a relative age of 20%-50% before decreasing as the convective cloud complex decayed. Ice particle diameter decreased with distance from the core but generally increased with storm age. These results, which characterize the average convective system during the experiment, should be valuable for formulating and validating convective cloud process models.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  3. 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)

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

    1991-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Jurković, Petra Mikuš; Mahović, Nataša Strelec; Počakal, Damir

    2015-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    Relativistic 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.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  8. Hybrid ensemble-3DVar radar data assimilation for the short-term prediction of convective storms

    NASA Astrophysics Data System (ADS)

    Carley, Jacob R.

    This two-part study develops and tests a hybrid ensemble-3DVar radar data assimilation system for the short-term prediction of convective storms. A key component of this work is the use of the operational regional numerical weather prediction infrastructure of the United States National Weather Service (NWS). Recently, the NWS's Gridpoint Statistical Interpolation system (GSI) has been extended to include a hybrid ensemble-3DVar assimilation capability, allowing for the inclusion of flow dependent background error statistics in the 3DVar cost function. A convenient aspect of the hybrid ensemble-3DVar approach is its resource manageability. The initial implementation of the system may only use 3DVar and the hybrid aspect can be implemented gradually where additional ensemble members can be added as computational resources allow. Therefore the hybrid ensemble-3DVar method may be a particularly appealing approach for an operational numerical weather prediction (NWP) center where resources are at a premium. The first part of this study focuses on the development of a storm-scale, hybrid ensemble-3DVar radar data assimilation system. An observation operator for radar reflectivity is introduced, static background errors for additional hydrometeor control variables are obtained, an ensemble prediction system is implemented, and an algorithm is developed to assimilate radar observations. This system is applied to a real-data case which exhibits varying convective modes. It is found that, when compared to 3DVar, the hybrid ensemble-3DVar assimilation approach provides a closer fit to observations, produces cold pools which are much stronger than what was observed in the 3DVar experiment, and all experiments have a vertical velocity field at the final analysis time which exhibits generally weak upward vertical motion fields. The weak vertical motion field is hypothesized to be a result of the lack of vertical velocity control variable and thus there is no coupling amongst the three components of the wind. The second part of this study tests the radar data assimilation experiments through the evaluation of short, 1 hour forecasts initialized from the storm-scale analyses. It is found that the weak upward vertical velocity fields found in the storm-scale analyses did not preclude the development of deep convective storms with upward vertical motion representative of the observed storm types. In all radar data assimilation experiments a general eastward displacement of forecast storms relative to observed storms is observed. This displacement is hypothesized to be a result of storm re-development along cold pools during the first 10 to 20 minutes of the forecast. Furthermore, objective verification indicates that radar data assimilation compared to a case of no data assimilation generally improves the forecasts, and hybrid ensemble-3DVar assimilation yielded initial conditions which provided the best forecasts. A sensitivity was noted to the relative weights given to the static- and ensemble-based background error statistics. Experiments with 50% and 25% of the weight given to the static background error generally yielded the best forecast verification scores overall. It is noted that while these results demonstrate the effectiveness of hybrid ensemble-3DVar radar data assimilation at the convective-scale with the regional operational NWP infrastructure of the NWS, this is only an evaluation with a single case. Additional case studies are recommended before a more general conclusion may be obtained.

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

    SciTech Connect

    Heimpel, Moritz; Aurnou, Jonathan M. E-mail: aurnou@ucla.edu

    2012-02-10

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

  10. Convective Bursts and the Coupling of Saturn's Equatorial Storms and Interior Rotation

    NASA Astrophysics Data System (ADS)

    Heimpel, Moritz; Aurnou, Jonathan M.

    2012-02-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  13. Improving storm-scale analyses of convection via assimilation of polarimetric radar observations

    NASA Astrophysics Data System (ADS)

    Romine, Glen Scott

    Quantitative precipitation forecasting is one of the greatest challenges currently facing the operational meteorological community. Modern short-term numerical forecasts only provide limited guidance owing to their coarse spatial and temporal resolution in comparison to the smaller scales needed to capture individual storms and their use of bulk-microphysical schemes. Further, convective events are often poorly resolved by the operational observing network, leading to poor analyses of the initial atmospheric state and subsequently poor forecasts. Presently, the Doppler radar network offers the only volumetric data suitable for more accurate assimilation on the storm scale. With polarimetric upgrades to the operational Doppler network underway, assimilating polarimetric radar observations will allow further improvement in the estimating the current atmospheric state. Further, more accurate retrieval of unobserved fields in real time, such as the low-level cold pool beneath supercell storms, would aid forecasters in current and future hazard assessment. An existing ensemble Kalman filter data assimilation system developed at NSSL was upgraded to enable assimilation of real polarimetric radar observations through integration of an advanced dual-moment microphysical scheme and through development of forward operators for the polarimetric radar observables. The resulting differential reflectivity and specific differential phase operators have been shown to produce realistic polarimetric radar signatures for an observed supercell storm event. In addition, the system provided good retrieval of storm kinematic features that were enhanced through use of advanced microphysics and assimilation of polarimetric radar observations. A detailed examination of the case study led to new insight into polarimetric field evolution associated with a significantly tornadic supercell thunderstorm. This included the identification of a specific differential phase foot and differential reflectivity shield as well as the first documentation focused on the relationship between polarimetric field evolution relative to surface gust front behavior. A strong but compact cold pool was found on the upshear side of the storm. However, an intriguing discovery was the lack of significant cooling at the surface within the forward flank downdraft region of the storm. Instead, there was an elevated cold pool along the forward storm flank that rested on a capping inversion layer. Comparison of the retrieved atmospheric state variables between the simple and advanced microphysical representation showed significant differences in spatial and temporal evolution, yet retrieved cold pool characteristics were qualitatively quite similar to one another and observations. This is related to the similar treatment of evaporation between the two microphysical schemes along the upshear side of the storm.

  14. Impact of Thermal Perturbations from Urban Runoff During Summer Storms on Stream and Wetland Temperatures

    NASA Astrophysics Data System (ADS)

    Hester, E. T.

    2009-12-01

    Runoff from heated parking lots during summer thunderstorms injects pulses of hot water into receiving water bodies. If the magnitude of such thermal perturbations is sufficient, aquatic organisms can be impacted. Such concerns are heightened because climate change will likely raise the temperature and reduce the magnitude of baseflow in aquatic systems. These pulses of elevated temperature also represent an opportunity to study how perturbations move through aquatic systems and how their migration is affected by physical parameters such as current velocity and channel form. While previous studies have determined that the impact of summer storm thermal pulses on stream temperatures can be significant, none have fully resolved the spatial extent and magnitude of these impacts in space or time in receiving streams nor compared impacts among different types of water bodies. Here we present preliminary temperature timeseries data collected using arrays of wireless temperature sensors in two example waterbodies (a stream with directional flow and a wetland with minimal current) immediately downstream of the outlet of storm sewers draining large nearby parking lots on the Virginia Tech campus in Blacksburg, VA. These data are useful to quantify the amplitude, duration, and evolution of thermal perturbations from individual storms and how these vary with current velocity, weather conditions, and other factors. We compare the magnitude of measured perturbations in the receiving water body to thermal tolerance data for aquatic species to evaluate expected biological impacts. We also outline future research planned on this topic.

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

    NASA Astrophysics Data System (ADS)

    Cunningham, Philip; Reeder, Michael J.

    2009-06-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  17. Gravity shear waves atop the cirrus layer of intense convective storms

    NASA Technical Reports Server (NTRS)

    Stobie, J. G.

    1975-01-01

    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.

  18. A case study of gravity waves-convective storms interaction 9 May 1979

    NASA Technical Reports Server (NTRS)

    Stobie, J. G.; Einaudi, F.; Uccellini, L. W.

    1983-01-01

    An analysis is presented of a series of severe storms which occurred in the north central United States on 9 May 1979 and whose spatial distribution and movement correlate well with observed gravity waves. Two gravity wave trains of 2.1-3 mb amplitude, 2.5-3.3 h period and 240-265 km horizontal wavelength were isolated through power spectra analysis and cross-correlation techniques applied to National Weather Service barograph traces. The wave trains propagated in the 200 deg direction, which coincided with the jet axis, with a phase velocity of 20-30 m/s and within a 300 km wide band. The storms were identified on enhanced infrared GOES satellite pictures with the help of radar summaries. These convective systems initially developed in Nebraska and propagated north-northeast at 25 m/s, revealing wave-like characteristics with a separation of 300-400 km. The convective systems were closely linked to the observed wave trains with cell intensity, height and associated rainfall maximized at the wave ridge. One of the two wave trains developed in regions of weak or no convection and appeared to initiate more intense convective clusters downstream from the point of origin. It is shown that the characteristics of the wave trains are consistent with those of gravity waves generated in a region of strong vertical shear associated with the jet. It is suggested that the wave trains continue to extract energy from the basic state all along their track through critical level interaction.

  19. On the mutual interactions between convective storms and their environments during the midlatitude continental convective clouds experiment (mc3e) field campaign in oklahoma

    NASA Astrophysics Data System (ADS)

    Bang, Sarah Doherty

    This work examines in detail the lifecycles of the convection on 20, 23, and 24 May 2011 during the Midlatitude Continental Convective Clouds Experiment (MC3E) field experiment in Oklahoma. Furthermore, specific attention is given to the environmental mechanisms that affect the propagation, maintenance, strength, and morphology of organized convection for the duration of the three cases. This study was conducted using the MC3E field campaign observational database, with particular emphasis on ground and airborne radar, radiosonde, and Oklahoma Mesonet data. This work was motivated by the goals of the MC3E field campaign, including improved understanding of convective evolution, organized convection, microphysics, ultimately leading to improvement of parameterization of convection and mesoscale processes in weather and climate models, and improvement of retrievals of precipitation by remote sensing. The three cases examined exhibited leading line/trailing stratiform mesoscale convective system, supercell, and back-building convective structures, each with a complex evolution. From the data analyzed for these cases, we suggest that given certain initial conditions, the vertical wind shear profile is the dominant factor in the determination of storm morphology. If the source of the buoyant updraft is renewed throughout a system's lifetime, then a convective system's propagation and longevity is tied strongly to the strength of the cold pool produced by convective downdrafts, and formation of new convection along the boundaries of the pool.

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

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Notaro, M.

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Dobrovolný, Petr; Brázdil, Rudolf

    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.

  2. Sprite-producing Convective Storms within the Colorado Lightning Mapping Array

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  4. Recent Satellite Studies of Extreme Convective Storms over North America, South Asia and South America

    NASA Astrophysics Data System (ADS)

    Houze, R.

    2012-12-01

    The existence of radar in space on the Tropical Rainfall Measuring Mission (TRMM) satellite has made it possible to compare the behavior of deep intense convective storms in different parts of the world. These comparisons have brought out similarities in the way large mountain ranges help control the occurrence of extreme convection. Common factors are: 1) low-level flow from a warm moisture source channeled in part by the mountain range; 2) midlevel flow subsiding from high terrain and capping the warm moist layer; and 3) a triggering mechanism. These three elements are present for convective clouds forming near the Rockies, Andes, and Himalayas. In the case of the Rockies, the moist source is the Gulf of Mexico; in South Asia it is the Arabian Sea; and for the Andes it is the wet Amazon Basin. In the U.S., the low-level flow northward from the Gulf is overridden by midlevel air descending from the Mexican Plateau. In South Asia, eastward midlevel flow comes down the face of the Afghan Plateau and caps the moist flow from the Arabian Sea. In South America, at the latitude of Argentina, westerly midlevel flow traverses the ridge of the Andes and descends over low-level moist flow being channeled southward from the Amazon Basin. In the U.S. case, triggering is usually by some synoptic or mesoscale flow feature (e.g. a front). However, in the South Asian and South American cases, the triggering that breaks the cap formed by the descending midlevel flow is orographic; when the low-level moist jet impinges on a foothill or small mountain near the base of the major barrier the cap is removed and the convection erupts. These analyses show that outbreaks of of extreme convection are delicately controlled by the juxtaposition of low-level moist flow, mid-level flow, large mountain ranges, and small hills. Changing flow patterns in a warming world could alter the ways in which these factors come together climatologically. However, knowing the key factors involved will help understand how changing patterns of severe convection might occur as circulation patterns evolve.

  5. Generation of a severe convective ionospheric storm under stable Rayleigh-Taylor conditions: triggering by meteors?

    NASA Astrophysics Data System (ADS)

    Kelley, M. C.; Ilma, R. R.

    2016-02-01

    Here we report on four events detected using the Jicamarca Radio Observatory (JRO) over an 18-year period, in which huge convective ionospheric storms (CISs) occur in a stable ionosphere. We argue that these rare events could be initiated by meteor-induced electric fields. The meteor-induced electric fields map to the bottomside of the F region, causing radar echoes and a localized CIS. If and when a localized disturbance reaches 500 km, we argue that it becomes two-dimensionally turbulent and cascades structure to both large and small scales. This leads to long-lasting structure and, almost certainly, to scintillations over a huge range of latitudes some ±15° wide and to 3 m irregularities, which backscatter the VHF radar waves. These structures located at high altitudes are supported by vortices shed by the upwelling bubble in a vortex street.

  6. Aerosol impacts on deep convective storms in the tropics: A combination of modeling and observations

    NASA Astrophysics Data System (ADS)

    Storer, Rachel Lynn

    It is widely accepted that increasing the number of aerosols available to act as cloud condensation nuclei (CCN) will have significant effects on cloud properties, both microphysical and dynamical. This work focuses on the impacts of aerosols on deep convective clouds (DCCs), which experience more complicated responses than warm clouds due to their strong dynamical forcing and the presence of ice processes. Several previous studies have seen that DCCs may be invigorated by increasing aerosols, though this is not the case in all scenarios. The precipitation response to increased aerosol concentrations is also mixed. Often precipitation is thought to decrease due to a less efficient warm rain process in polluted clouds, yet convective invigoration would lead to an overall increase in surface precipitation. In this work, modeling and observations are both used in order to enhance our understanding regarding the effects of aerosols on DCCs. Specifically, the area investigated is the tropical East Atlantic, where dust from the coast of Africa frequently is available to interact with convective storms over the ocean. The first study investigates the effects of aerosols on tropical DCCs through the use of numerical modeling. A series of large-scale, two-dimensional cloud-resolving model simulations was completed, differing only in the concentration of aerosols available to act as CCN. Polluted simulations contained more deep convective clouds, wider storms, higher cloud tops and more convective precipitation across the entire domain. Differences in the warm cloud microphysical processes were largely consistent with aerosol indirect theory, and the average precipitation produced in each DCC column decreased with increasing aerosol concentration. A detailed microphysical budget analysis showed that the reduction in collision and coalescence largely dominated the trend in surface precipitation; however the production of rain through the melting of ice, though it also decreased, became more important as the aerosol concentration increased. The DCCs in polluted simulations contained more frequent, stronger updrafts and downdrafts, but the average updraft speed decreased with increasing aerosols in DCCs above 6 km. An examination of the buoyancy term of the vertical velocity equation demonstrates that the drag associated with condensate loading is an important factor in determining the average updraft strength. The largest contributions to latent heating in DCCs were cloud nucleation and vapor deposition onto water and ice, but changes in latent heating were, on average, an order of magnitude smaller than those in the condensate loading term. It is suggested that the average updraft is largely influenced by condensate loading in the more extensive stratiform regions of the polluted storms, while invigoration in the convective core leads to stronger updrafts and higher cloud tops. The goal of the second study was to examine observational data for evidence that would support the findings of the modeling work. In order to do this, four years of CloudSat data were analyzed over a region of the East Atlantic, chosen for the similarity (in meteorology and the presence of aerosols) to the modeling study. The satellite data were combined with information about aerosols taken from the output of a global transport model, and only those profiles fitting the definition of deep convective clouds were analyzed. Overall, the cloud center of gravity, cloud top, rain top, and ice water path were all found to increase with increased aerosol loading. These findings are in agreement with what was found in the modeling work, and are suggestive of convective invigoration with increased aerosols. In order to separate environmental effects from that due to aerosols, the data were sorted by environmental convective available potential energy (CAPE) and lower tropospheric static stability (LTSS). The aerosol effects were found to be largely independent of the environment. A simple statistical test suggests that the difference between the cleanest and most polluted clouds sampled are significant, lending credence to the hypothesis of convective invigoration. This is the first time evidence of deep convective invigoration has been demonstrated within a large region and over a long time period, and it is quite promising that there are many similarities between the modeling and observational results.

  7. UV dosage levels in summer: increased risk of ozone loss from convectively injected water vapor.

    PubMed

    Anderson, James G; Wilmouth, David M; Smith, Jessica B; Sayres, David S

    2012-08-17

    The observed presence of water vapor convectively injected deep into the stratosphere over the United States can fundamentally change the catalytic chlorine/bromine free-radical chemistry of the lower stratosphere by shifting total available inorganic chlorine into the catalytically active free-radical form, ClO. This chemical shift markedly affects total ozone loss rates and makes the catalytic system extraordinarily sensitive to convective injection into the mid-latitude lower stratosphere in summer. Were the intensity and frequency of convective injection to increase as a result of climate forcing by the continued addition of CO(2) and CH(4) to the atmosphere, increased risk of ozone loss and associated increases in ultraviolet dosage would follow. PMID:22837384

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  10. The evolution of convective storms from their footprints on the sea as viewed by synthetic aperture radar from space

    NASA Technical Reports Server (NTRS)

    Atlas, David; Black, Peter G.

    1994-01-01

    SEASAT synthetic aperture radar (SAR) echoes from the sea have previously been shown to be the result of rain and winds produced by convective stroms; rain damps the surface waves and causes ech-free holes, while the diverging winds associated with downdraft generate waves and associated echoes surrounding the holes. Gust fronts are also evident. Such a snapshot from 8 July 1978 has been examined in conjunction with ground-based radar. This leads to the conclusion that the SAR storm footprints resulted from storm processes that occurred up to an hour or more prior to the snapshot. A sequence of events is discerned from the SAR imagery in which new cell growth is triggered in between the converging outflows of two preexisting cells. In turn, the new cell generates a mini-squall line along its expanding gust front. While such phenomena are well known over land, the spaceborne SAR now allows important inferences to be made about the nature and frequency of convective storms over the oceans. The storm effects on the sea have significant implications for spaceborne wind scatterometry and rainfall measurements. Some of the findings herein remain speculative because of the great distance to the Miami weather radar-the only source of corroborative data.

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

    NASA Astrophysics Data System (ADS)

    Lee, D. Y.; Ahn, J. B.; Yoo, J. H.

    2014-12-01

    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 (ENSO) 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 (EASMI) or each MP index (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 statistical-empirical 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 the statistical-empirical method compared to the dynamical models. Acknowledgements This work was carried out with the support of the Rural Development Administration Cooperative Research Program for Agriculture Science and Technology Development under Grant Project No. PJ009953, Republic of Korea.

  12. Relationships between convective storms and their environment in AVE IV determined from a three-dimensional subsynoptic-scale, trajectory model

    NASA Technical Reports Server (NTRS)

    Wilson, G. S.

    1977-01-01

    The paper describes interrelationships between synoptic-scale and convective-scale systems obtained by following individual air parcels as they traveled within the convective storm environment of AVE IV. (NASA's fourth Atmospheric Variability Experiment, AVE IV, was a 36-hour study in April 1975 of the atmospheric variability and structure in regions of convective storms.) A three-dimensional trajectory model was used to calculate parcel paths, and manually digitized radar was employed to locate convective activity of various intensities and to determine those trajectories that traversed the storm environment. Spatial and temporal interrelationships are demonstrated by reference to selected time periods of AVE IV which contain the development and movement of the squall line in which the Neosho tornado was created.

  13. Airborne quantification of upper tropospheric NOx production from lightning in deep convective storms over the United States Great Plains

    NASA Astrophysics Data System (ADS)

    Pollack, I. B.; Homeyer, C. R.; Ryerson, T. B.; Aikin, K. C.; Peischl, J.; Apel, E. C.; Campos, T.; Flocke, F.; Hornbrook, R. S.; Knapp, D. J.; Montzka, D. D.; Weinheimer, A. J.; Riemer, D.; Diskin, G.; Sachse, G.; Mikoviny, T.; Wisthaler, A.; Bruning, E.; MacGorman, D.; Cummings, K. A.; Pickering, K. E.; Huntrieser, H.; Lichtenstern, M.; Schlager, H.; Barth, M. C.

    2016-02-01

    The reported range for global production of nitrogen oxides (NOx = NO + NO2) by lightning remains large (e.g., 32 to 664 mol NOx flash-1), despite incorporating results from over 30 individual laboratory, theoretical, and field studies since the 1970s. Airborne and ground-based observations from the Deep Convective Clouds and Chemistry experiment in May and June 2012 provide a new data set for calculating moles of NOx produced per lightning flash, P(NOx), in thunderstorms over the United States Great Plains. This analysis utilizes a combination of in situ observations of storm inflow and outflow from three instrumented aircraft, three-dimensional spatial information from ground-based radars and satellite observations, and spatial and temporal information for intracloud and cloud-to-ground lightning flashes from ground-based lightning mapping arrays. Evaluation of two analysis methods (e.g., a volume-based approach and a flux-based approach) for converting enhancements in lightning-produced NOx from volume-based mixing ratios to moles NOx flash-1 suggests that both methods equally approximate P(NOx) for storms with elongated anvils, while the volume-based approach better approximates P(NOx) for storms with circular-shaped anvils. Results from the more robust volume-based approach for three storms sampled over Oklahoma and Colorado during DC3 suggest a range of 142 to 291 (average of 194) moles NOx flash-1 (or 117-332 mol NOx flash-1 including uncertainties). Although not vastly different from the previously reported range for storms occurring in the Great Plains (e.g., 21-465 mol NOx flash-1), results from this analysis of DC3 storms offer more constrained upper and lower limits for P(NOx) in this geographical region.

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

    NASA Technical Reports Server (NTRS)

    Zipser, Edward J.; Lutz, Kurt R.

    1994-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Globally, changes in stable isotope ratios of oxygen and hydrogen (δ18O and δD) in the meteoric water cycle result from distillation and evaporation processes. Isotope fractionation occurs when air masses rise in elevation, cool, and reduce their water-vapor holding capacity with decreasing temperature. As such, d18O and dD values from a variety of sedimentary archives are often used to reconstruct changes in continental paleohydrology as well as paleoaltimetry of mountain ranges. Based on 234 stream-water samples, we demonstrate that areas experiencing deep convective storms in the eastern south-central Andes (22 - 28° S) do not show the commonly observed relationship between δ18O and δD with elevation. These convective storms arise from intermontane basins, where diurnal heating forces warm air masses upward, resulting in cloudbursts and raindrop evaporation. Especially at the boundary between the tropical and extra-tropical atmospheric circulation regimes where deep-convective storms are very common (~ 26° to 32° N and S), the impact of such storms may yield non-systematic stable isotope-elevation relationships as convection dominates over adiabatic lifting of air masses. Because convective storms can reduce or mask the depletion of heavy isotopes in precipitation as a function of elevation, linking modern or past topography to patterns of stable isotope proxy records can be compromised in mountainous regions, and atmospheric circulation models attempting to predict stable isotope patterns must have sufficiently high spatial resolution to capture the fractionation dynamics of convective cells. Rohrmann, A. et al. Can stable isotopes ride out the storms? The role of convection for water isotopes in models, records, and paleoaltimetry studies in the central Andes. Earth Planet. Sci. Lett. 407, 187-195 (2014).

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

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

    USGS Publications Warehouse

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

    2011-01-01

    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 ongoing 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. ?? 2011 Author(s).

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

    USGS Publications Warehouse

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

    2011-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

    The increasing damages caused by natural disasters, a great part of them being direct or indirect effects of severe convective storms (SCS), seem to suggest that extreme events occur with greater frequency, also as a consequence of climate changes. A better comprehension of the genesis and evolution of SCS is then necessary to clarify if and what is changing in these extreme events. The major reason to go through the mechanisms driving such events is given by the growing need to have timely and precise predictions of severe weather events, especially in areas that show to be more and more sensitive to their occurrence. When dealing with severe weather events, either from a researcher or an operational point of view, it is necessary to know precisely the conditions under which these events take place to upgrade conceptual models or theories, and consequently to improve the quality of forecasts as well as to establish effective warning decision procedures. The Mediterranean basin is, in general terms, a sea of small areal extent, characterised by the presence of several islands; thus, a severe convection phenomenon originating over the sea, that lasts several hours, is very likely to make landfall during its lifetime. On the other hand, these storms are quasi-stationary or very slow moving so that, when convection happens close to the shoreline, it is normally very dangerous and in many cases can cause very severe weather, with flash floods or tornadoes. An example of these extreme events is one of the case study analysed in this work, regarding the flash flood occurred in Giampileri (Sicily, Italy) the evening of 1st October 2009, where 18 people died, other 79 injured and the historical centre of the village seriously damaged. Severe weather systems and strong convection occurring in the Mediterranean basin have been investigated for two years (2008-2009) using geostationary (MSG) and polar orbiting (AVHRR) satellite data, supported by ECMWF analyses and severe weather reports. The spatial and seasonal variability of storm occurrence have been also analysed, as well as the most favourable synoptic conditions for their formation. The analysis shows the existence of preferential areas of genesis of these extreme events, mainly located in the central Mediterranean (i.e., Ionic and Tyrrhenian seas), where the storms develop and grow preferentially in fall. The synoptic features, identified as precursors of severe convective events genesis, show how the totality of the identified cases occur in mid-troposphere (500 hPa) troughs or cut-off circulation within southerly flow, with values of deep level shear of at least 15 m s-1 and high θe (850 hPa) values. Among all the detected cases of severe convection, two selected cases of enhanced-V features are presented in detail, either for the different synoptic environments in which they are embedded, and for being long-lived or severe in terms of heavy rainfall and damages they produced at the ground. In a long-term perspective, this preliminary study aims to make a climatological database of severe weather events occurring in the Mediterranean sea which may critically impact on the Italian peninsula and potentially affect population, in order to develop an objective procedure which can support regional meteorological services in forecasting extreme events, their development and impact, for taking proper early decisions.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Globally, changes in stable isotope ratios of oxygen and hydrogen (δ 18O and δ 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, δ 18O and δ 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 δ 18O and δ 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.

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

    NASA Astrophysics Data System (ADS)

    Vadas, Sharon; Yue, Jia; Nakamura, Takuji

    2012-04-01

    We report on six continuous hours of OH airglow imager observations (at z 87 km) of convectively generated gravity waves (GWs) near Fort Collins, Colorado, on the evening of 08 September 2005. These GWs appeared as nearly concentric rings, and had epicenters near the locations of deep convection in three thunderstorms in Colorado, Nebraska and South Dakota. Using GOES satellite and weather radar observations, we show that the GWs closely follow the thunderstorms. Using the background wind from a nearby radar, the intrinsic wave parameters and vertical wavelengths are calculated. The temperature perturbations are estimated to be T?/T 1-3% for GWs with horizontal wavelengths ?h 20-40 km and horizontal phase speeds 40-60 m/s. The horizontal wavelengths of GWs from a convective cluster decreased in time from 30 to 15 km. We employ convective plume and ray-trace models to simulate the GW-induced OH intensity perturbations from convective plumes, clusters and complexes. We find that the results using the background model wind (radiosonde/TIME-GCM) agree well with the late-time observations, when the images are dominated by southwestward, short-wavelength, high-frequency GWs. These late-time GWs propagate against the background wind, and have ?h 30-40 km and periods of ? 20-30 min. The OH intensity perturbations are enhanced because the vertical wavelengths ?z increased, T?/T increased, and the vertical velocity perturbations w? decreased (because the GWs were near their reflection levels). We also find that these short-wavelength GWs were created 5 h earlier by an extremely energetic, deep convective plume in South Dakota, thereby showing that small-scale, convective GWs directly link the troposphere and mesopause region.

  3. Seasonal Variability of Storm Top Altitudes in the Tropics and Subtropics Observed by TRMM PR

    NASA Astrophysics Data System (ADS)

    Chen, Fengjiao; Fu, Yunfei; Liu, Peng; Yang, Yuanjian

    2016-03-01

    Seasonal variability of storm top altitudes for convective and stratiform precipitation in the tropics and subtropics are investigated based on measurements of the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) from 1998 to 2011. Statistically, the spatial distribution of mean convective storm top altitudes shows a large variation between land and ocean, while the stratiform storm tops exhibit insignificant land-ocean differences. Seasonal variances of tropical convective and stratiform storm top altitudes are small, with their means are approximately at 5 km (6 km) and 5.5 km (6 km) over the ocean (land) in each season. In the subtropics, the difference of the storm top altitudes between summer and winter reaches ~ 4 km and ~ 2 km for convective and stratiform precipitation, respectively. The zonal mean storm top altitudes of stratiform precipitation are highly correlated with the zonal averaged air temperature and sea surface temperature. Additionally, the mean storm tops of higher altitudes correspond with larger mean rain rates for both convective and stratiform precipitation at the seasonal scale. Such relationship satisfies the quadratic functions with a correlation coefficient of 0.9. On the basis of this relationship, the summer mean rain rates are retrieved from storm top altitudes, which are 1-3 mm/h and 0.3-0.9 mm/h smaller than the observed ones, for convective and stratiform precipitation, respectively. These results suggest that the quadratic function between storm top altitudes and rain rates have potential applications in precipitation parameterization of models and climatic studies.

  4. A storm modeling system as an advanced tool in prediction of well organized slowly moving convective cloud system and early warning of severe weather risk

    NASA Astrophysics Data System (ADS)

    Spiridonov, Vlado; Curic, Mladjen

    2015-02-01

    Short-range prediction of precipitation is a critical input to flood prediction and hence the accuracy of flood warnings. Since most of the intensive processes come from convective clouds-the primary aim is to forecast these small-scale atmospheric processes. One characteristic pattern of organized group of convective clouds consist of a line of deep convection resulted in the repeated passage of heavy-rain-producing convective cells over NW part of Macedonia along the line. This slowly moving convective system produced extreme local rainfall and hailfall in urban Skopje city. A 3-d cloud model is used to simulate the main storm characteristic (e.g., structure, intensity, evolution) and the main physical processes responsible for initiation of heavy rainfall and hailfall. The model showed a good performance in producing significantly more realistic and spatially accurate forecasts of convective rainfall event than is possible with current operational system. The output results give a good initial input for developing appropriate tools such as flooding indices and potential risk mapping for interpreting and presenting the predictions so that they enhance operational flood prediction capabilities and warnings of severe weather risk of weather services. Convective scale model-even for a single case used has proved significant benefits in several aspects (initiation of convection, storm structure and evolution and precipitation). The storm-scale model (grid spacing-1 km) is capable of producing significantly more realistic and spatially accurate forecasts of convective rainfall events than is possible with current operational systems based on model with grid spacing 15 km.

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

    NASA Astrophysics Data System (ADS)

    Barthlott, Christian; Mühr, Bernhard; Hoose, Corinna

    2015-04-01

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

  6. High-latitude ionosphere convection and Birkeland current response for the 15 May 2005 magnetic storm recovery phase

    NASA Astrophysics Data System (ADS)

    Eriksson, S.; Hairston, M. R.; Rich, F. J.; Korth, H.; Zhang, Y.; Anderson, B. J.

    2008-03-01

    The high-latitude response of sunward E B flow and Birkeland field-aligned currents (FAC) is analyzed for the 15 May 2005 magnetic cloud that generated a great magnetic storm (SYM-H = -305 nT at 0820 UT). The interplanetary magnetic field (IMF) clock angle, ? = arctan(By/Bz), gradually rotated from 65 to -80 during the 10-h long northward IMF period and the recovery of this storm. DMSP observations confirm a dawnward migration of a Northern Hemisphere sunward E B flow channel (FC) between a downward and upward FAC pair. This FAC system developed during southward IMF (? = 109) at the poleward edge of the duskside auroral oval as part of a four-sheet FAC system 23 min before the IMF became northward. TIMED/GUVI observations show that the dawnward migration of the upward FAC coincides with a drifting transpolar auroral arc (TPA). IMAGE/WIC did not observe a TPA in the southern (winter) hemisphere. DMSP and Iridium observations are in good agreement with MHD simulation predictions of a northward IMF reorientation of high-latitude FACs. The northern FC migration was likely due to summer hemisphere conductances, a strong average IMF Bx = -35 nT and the sunward dipole tilt angle that favor a northern high-latitude reconnection mechanism for a well-organized sunward FC and FAC system migration. The storm recovery rate appeared to be related with the region 2 FAC. A fast 11.4 nT/h rate was observed for a weak or nonexistent region 2 system during the high-latitude FAC redistribution. The SYM-H recovery slowed significantly to 0.9 nT/h following the 1800 UT region 2 system recovery.

  7. Summer-winter hemisphere asymmetry of the preliminary reverse impulse of geomagnetic storm sudden commencements at midlatitudes

    NASA Astrophysics Data System (ADS)

    Sastri, J. H.; Yumoto, K.; Rao, J. V. S. V.; Ikeda, A.

    2008-05-01

    We present event-specific observational evidence for the prevalence of a summer-winter hemisphere asymmetry of the preliminary reverse impulse (PRI) of geomagnetic storm sudden commencements (SSCs) at midlatitudes of the local afternoon sector. The evidence is culled from the archived 10-s resolution data of midlatitude stations (geomagnetic latitude 23-46°) of the MM 210 magnetometer network. The hemisphere asymmetry is characterized by a larger peak amplitude of PRI in the summer hemisphere than in the winter hemisphere, and this feature is more prominently seen in the December solstice compared to the June solstice. In the December solstice SSC event, the amplitude of the preliminary reverse impulse, PRI (4.8 nT) at BRV (geomagnetic latitude 36.6°S) in the summer hemisphere is larger by a factor of 6 compared to that at MSR (geomagnetic latitude 37.6°N) in the winter hemisphere. The asymmetry is also apparent at lower latitudes: while the PRI assumed an amplitude of 3.7 nT at LEM (geomagnetic latitude 34.1°S), it is barely discernible at ONW (geomagnetic latitude 31.6°N) in the winter hemisphere. In the June solstice event, the PRI amplitude at RIK (geomagnetic latitude 34.7°N) in the summer hemisphere is higher by a factor of 3.44 compared to that at LEM (geomagnetic latitude 34.1°S) in the winter hemisphere. A similar behavior is also apparent in the equinox event though the hemisphere asymmetry of the preliminary reverse impulse (PRI) here is of moderate strength. In all the SSC events studied, the main impulse (MI) amplitude also exhibited the well-known summer-winter asymmetry, but the hemisphere asymmetry is more prominent with the preliminary reverse impulse (PRI) than with the main impulse (MI). Physical processes that could possibly account for the hemisphere asymmetry evidenced of the afternoon PRI at midlatitudes are discussed.

  8. High resolution radiometric measurements of convective storms during the GATE experiment

    NASA Technical Reports Server (NTRS)

    Fowler, G.; Lisa, A. S.

    1976-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

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

  10. Assessing the relationship between high lightning events and storm mode in northern and central Alabama

    NASA Astrophysics Data System (ADS)

    Willis, Morgan Terry

    Lightning is a dangerous and deadly hazard, yet it is often underestimated by the public and excluded from severe weather watches and warnings used by the National Weather Service. Previous studies have analyzed the relationship of lightning and storm intensity in relation to severe weather, but none have analyzed this relationship across all storm modes in an area including Northern and Central Alabama. This study attempts to assess the relationship between cloud-to-ground (CG) lightning and storm mode in storm events which occurred on lightning hazard days in Northern and Central Alabama during the years of 2007 to 2011. Storm variables for analysis included lightning flash rate, aspect ratio, total convective area above 20 dBZ, maximum convective area above 40 dBZ, and percent maximum convective area. Results show that lightning flash rates vary by season and storm mode. PCA and Cluster Analysis identified a total of 5 clusters of varying lightning flash rate and convective intensity. The storm mode events include non-summer linear, an anomalous MCS associated with a triple point frontal outflow boundary, summer airmass, non-seasonal weak, and summer MCS/MCC. Information obtained during this thesis has the potential to aid forecasters and emergency managers in Northern and Central Alabama by associating lightning flash rates with storm mode characteristics observed on lightning hazard days.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Boccippio, Dennis J.

    2002-01-01

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

  13. Simulation of quasi-linear mesoscale convective systems in northern China: Lightning activities and storm structure

    NASA Astrophysics Data System (ADS)

    Li, Wanli; Qie, Xiushu; Fu, Shenming; Su, Debin; Shen, Yonghai

    2016-01-01

    Two intense quasi-linear mesoscale convective systems (QLMCSs) in northern China were simulated using the WRF (Weather Research and Forecasting) model and the 3D-Var (three-dimensional variational) analysis system of the ARPS (Advanced Regional Prediction System) model. A new method in which the lightning density is calculated using both the precipitation and non-precipitation ice mass was developed to reveal the relationship between the lightning activities and QLMCS structures. Results indicate that, compared with calculating the results using two previous methods, the lightning density calculated using the new method presented in this study is in better accordance with observations. Based on the calculated lightning densities using the new method, it was found that most lightning activity was initiated on the right side and at the front of the QLMCSs, where the surface wind field converged intensely. The CAPE was much stronger ahead of the southeastward progressing QLMCS than to the back it, and their lightning events mainly occurred in regions with a large gradient of CAPE. Comparisons between lightning and non-lightning regions indicated that lightning regions featured more intense ascending motion than non-lightning regions; the vertical ranges of maximum reflectivity between lightning and non-lightning regions were very different; and the ice mixing ratio featured no significant differences between the lightning and non-lightning regions.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Berthet, Sarah; Rouquié, Bastien; Roca, Rémy

    2015-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

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

    USGS Publications Warehouse

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

    1994-01-01

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

  19. Performance Evaluation of PBL Schemes of ARW Model in Simulating Thermo-Dynamical Structure of Pre-Monsoon Convective Episodes over Kharagpur Using STORM Data Sets

    NASA Astrophysics Data System (ADS)

    Madala, Srikanth; Satyanarayana, A. N. V.; Srinivas, C. V.; Tyagi, Bhishma

    2015-11-01

    In the present study, advanced research WRF (ARW) model is employed to simulate convective thunderstorm episodes over Kharagpur (22°30'N, 87°20'E) region of Gangetic West Bengal, India. High-resolution simulations are conducted using 1 × 1 degree NCEP final analysis meteorological fields for initial and boundary conditions for events. The performance of two non-local [Yonsei University (YSU), Asymmetric Convective Model version 2 (ACM2)] and two local turbulence kinetic energy closures [Mellor-Yamada-Janjic (MYJ), Bougeault-Lacarrere (BouLac)] are evaluated in simulating planetary boundary layer (PBL) parameters and thermodynamic structure of the atmosphere. The model-simulated parameters are validated with available in situ meteorological observations obtained from micro-meteorological tower as well has high-resolution DigiCORA radiosonde ascents during STORM-2007 field experiment at the study location and Doppler Weather Radar (DWR) imageries. It has been found that the PBL structure simulated with the TKE closures MYJ and BouLac are in better agreement with observations than the non-local closures. The model simulations with these schemes also captured the reflectivity, surface pressure patterns such as wake-low, meso-high, pre-squall low and the convective updrafts and downdrafts reasonably well. Qualitative and quantitative comparisons reveal that the MYJ followed by BouLac schemes better simulated various features of the thunderstorm events over Kharagpur region. The better performance of MYJ followed by BouLac is evident in the lesser mean bias, mean absolute error, root mean square error and good correlation coefficient for various surface meteorological variables as well as thermo-dynamical structure of the atmosphere relative to other PBL schemes. The better performance of the TKE closures may be attributed to their higher mixing efficiency, larger convective energy and better simulation of humidity promoting moist convection relative to non-local schemes.

  20. Performance Evaluation of PBL Schemes of ARW Model in Simulating Thermo-Dynamical Structure of Pre-Monsoon Convective Episodes over Kharagpur Using STORM Data Sets

    NASA Astrophysics Data System (ADS)

    Madala, Srikanth; Satyanarayana, A. N. V.; Srinivas, C. V.; Tyagi, Bhishma

    2016-05-01

    In the present study, advanced research WRF (ARW) model is employed to simulate convective thunderstorm episodes over Kharagpur (22°30'N, 87°20'E) region of Gangetic West Bengal, India. High-resolution simulations are conducted using 1 × 1 degree NCEP final analysis meteorological fields for initial and boundary conditions for events. The performance of two non-local [Yonsei University (YSU), Asymmetric Convective Model version 2 (ACM2)] and two local turbulence kinetic energy closures [Mellor-Yamada-Janjic (MYJ), Bougeault-Lacarrere (BouLac)] are evaluated in simulating planetary boundary layer (PBL) parameters and thermodynamic structure of the atmosphere. The model-simulated parameters are validated with available in situ meteorological observations obtained from micro-meteorological tower as well has high-resolution DigiCORA radiosonde ascents during STORM-2007 field experiment at the study location and Doppler Weather Radar (DWR) imageries. It has been found that the PBL structure simulated with the TKE closures MYJ and BouLac are in better agreement with observations than the non-local closures. The model simulations with these schemes also captured the reflectivity, surface pressure patterns such as wake-low, meso-high, pre-squall low and the convective updrafts and downdrafts reasonably well. Qualitative and quantitative comparisons reveal that the MYJ followed by BouLac schemes better simulated various features of the thunderstorm events over Kharagpur region. The better performance of MYJ followed by BouLac is evident in the lesser mean bias, mean absolute error, root mean square error and good correlation coefficient for various surface meteorological variables as well as thermo-dynamical structure of the atmosphere relative to other PBL schemes. The better performance of the TKE closures may be attributed to their higher mixing efficiency, larger convective energy and better simulation of humidity promoting moist convection relative to non-local schemes.

  1. 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)

    Bao, Yan

    2013-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Chen, Wen

    2013-07-01

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

  3. Boreal summer intraseasonal variability simulated in the NCEP climate forecast system: insights from moist static energy budget and sensitivity to convective moistening

    NASA Astrophysics Data System (ADS)

    Sooraj, K. P.; Seo, Kyong-Hwan

    2013-09-01

    The NCEP Climate Forecast System (CFS) with the relaxed Arakawa Schubert (RAS, hereafter referred to as CTRL) convection scheme of Moorthi and Suarez exhibits better performance in representing boreal summer tropical intraseasonal variability as compared with a simulation using simplified Arakawa-Schubert scheme. The intraseasonal moist static energy (MSE) budget is analyzed in this version of the CFS model (CTRL), which produces realistic eastward and northward propagation characteristics. The moist and thermodynamic processes involved in the maintenance and propagation of the poleward moving intraseasonal oscillation (ISO) disturbances are examined here. Budget diagnostics show that horizontal MSE advection is the principal component of the budget, contributing to the poleward movement of the convection. The injection of MSE moistens the atmosphere north of the convective area causing the poleward movement of convection by destabilization of the atmosphere. The moistening process is mainly contributed by the climatological wind acting on the anomalous moisture gradient as confirmed from the examination of moisture advection equation. While surface enthalpy fluxes (consisting of radiative and surface turbulent heat fluxes) maintain the ISO anomalies, they oppose the MSE tendency due to horizontal advection thus regulating the poleward propagation characteristics. In addition, the model results show that wind-evaporation feedback dominates over cloud-radiation feedback for ISO propagation; this is in contrast to our estimates using the newly available European Centre for Medium Range Weather Forecasts Interim reanalysis. Sensitivity experiments suggest that intraseasonal variability in the CFS model with the RAS scheme is highly sensitive to the parameterization of both the shallow convection and the convective rain evaporation and downdrafts. Removal of these components adversely affects the propagation characteristics and greatly reduces the amplitude of intraseasonal variability. Our results support the primary importance of the moisture preconditioning ahead of the ISO and the physical relationship between moisture and precipitation. For realistic ISO simulations, models need to represent these features appropriately.

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

    NASA Astrophysics Data System (ADS)

    Bland, R. W.

    2010-12-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  6. Duskside enhancement of equatorial zonal electric field response to convection electric fields during the St. Patrick's Day storm on 17 March 2015

    NASA Astrophysics Data System (ADS)

    Tulasi Ram, S.; Yokoyama, T.; Otsuka, Y.; Shiokawa, K.; Sripathi, S.; Veenadhari, B.; Heelis, R.; Ajith, K. K.; Gowtam, V. S.; Gurubaran, S.; Supnithi, P.; Le Huy, M.

    2016-01-01

    The equatorial zonal electric field responses to prompt penetration of eastward convection electric fields (PPEF) were compared at closely spaced longitudinal intervals at dusk to premidnight sectors during the intense geomagnetic storm of 17 March 2015. At dusk sector (Indian longitudes), a rapid uplift of equatorial F layer to >550 km and development of intense equatorial plasma bubbles (EPBs) were observed. These EPBs were found to extend up to 27.13°N and 25.98°S magnetic dip latitudes indicating their altitude development to ~1670 km at apex. In contrast, at few degrees east in the premidnight sector (Thailand-Indonesian longitudes), no significant height rise and/or EPB activity has been observed. The eastward electric field perturbations due to PPEF are greatly dominated at dusk sector despite the existence of background westward ionospheric disturbance dynamo (IDD) fields, whereas they were mostly counter balanced by the IDD fields in the premidnight sector. In situ observations from SWARM-A and SWARM-C and Communication/Navigation Outage Forecasting System satellites detected a large plasma density depletion near Indian equatorial region due to large electrodynamic uplift of F layer to higher than satellite altitudes. Further, this large uplift is found to confine to a narrow longitudinal sector centered on sunset terminator. This study brings out the significantly enhanced equatorial zonal electric field in response to PPEF that is uniquely confined to dusk sector. The responsible mechanisms are discussed in terms of unique electrodynamic conditions prevailing at dusk sector in the presence of convection electric fields associated with the onset of a substorm under southward interplanetary magnetic field Bz.

  7. 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)

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

    2015-08-01

    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.

  8. 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)

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

    2014-09-01

    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.

  9. Rocket dust storms and detached dust layers in the Martian atmosphere

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  10. Vertical structure of cumulonimbus towers and intense convective clouds over the South Asian region during the summer monsoon season

    NASA Astrophysics Data System (ADS)

    Bhat, G. S.; Kumar, Shailendra

    2015-03-01

    The vertical structure of radar reflectivity factor in active convective clouds that form during the South Asian monsoon season is reported using the 2A25 version 6 data product derived from the precipitation radar measurements on board the Tropical Rainfall Measuring Mission satellite. We define two types of convective cells, namely, cumulonimbus towers (CbTs) and intense convective cells (ICCs). CbT is defined referring to a reflectivity threshold of 20 dBZ at 12 km altitude and is at least 9 km thick. ICCs are constructed referring to reflectivity thresholds at 8 km and 3 km altitudes. Cloud properties reported here are based on 10 year climatology. It is observed that the frequency of occurrence of CbTs is highest over the foothills of Himalayas, plains of northern India and Bangladesh, and minimum over the Arabian Sea and equatorial Indian Ocean west of 90E. The regional differences depend on the reference height selected, namely, small in the case of CbTs and prominent in 6-13 km height range for ICCs. Land cells are more intense than the oceanic ones for convective cells defined using the reflectivity threshold at 3 km, whereas land versus ocean contrasts are not observed in the case of CbTs. Compared to cumulonimbus clouds elsewhere in the tropics, the South Asian counterparts have higher reflectivity values above 11 km altitude.

  11. Features of clouds and convection during the pre- and post-onset periods of the Asian summer monsoon

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Wang, Chenghai

    2016-02-01

    The statistical characteristics of the vertical structure of clouds in the Asian summer monsoon region are investigated using two CloudSat standard products (Geometrical Profiling Product (GEOPROF) and GEOPROF-lidar) during the pre- and post-onset periods of the Asian summer monsoon, from April to August in 2007-2010. The characteristics of the vertical structure of clouds are analyzed and compared for different underlying surfaces in four subregions during this period. Also analyzed are the evolution of precipitation and hydrometeors with the northward advance of the Asian summer monsoon, and different hydrometeor characteristics attributed to the underlying surface features. The results indicate that the vertical cloud amounts increase significantly after the summer monsoon onset; this increase occurs first in the upper troposphere and then at lower altitudes over tropical regions (South Asian and tropical Northwest Pacific regions). The heights of the cloud top ascend, and the vertical height between the top and the base of the whole cloud increases. Single-layer (SL) and double-layer (DL) hydrometeors contribute over half and one third of the cloudiness in these 5 months (April to August), respectively. The multilayer frequencies increase in four different regions, and cloud layer depths (CLD) increase after the summer monsoon onset. These changes are stronger in tropical regions than in subtropical regions, while the vertical distance between cloud layers (VDCL) deceases in tropical regions and increases in subtropical regions.

  12. 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.

  13. Numerical Simulation of Martian Global Dust Storms and the Dust Cycle

    NASA Astrophysics Data System (ADS)

    Basu, S.; Richardson, M. I.; Wilson, J.; Ingersoll, A. P.

    2003-12-01

    We investigate the triggering, growth, decay and the inter-annual variability of global dust storms (GDS) on Mars. To date, testing of various theories of GDS initiation and variability has been limited by inability to numerically simulate spontaneous, variable storm development from realistic pre-storm model states. Here we describe General Circulation Model simulations that generate spontaneous and variable GDSs from realistic background conditions. Modelled GDSs produce dramatic increases in atmospheric dustiness, global-mean air temperatures, and atmospheric circulation, in accord with observations. The simulations generate global storms in southern spring and summer with significant inter-annual variability in size and timing of occurrence, including years with no storms. We propose a simple explanation for the observed dust cycle on Mars from our simulations. Stresses associated with large-scale (>300 km) wind systems initiate the large storms. Explosive growth results from the intensification of the Hadley circulation and the activation of secondary dust lifting centers. Away from great storms, the annually repeatable cycle of atmospheric temperatures and dust opacities observed in northern spring and summer is a result of convective (dust devil) lifting.

  14. Moist Convection

    NASA Astrophysics Data System (ADS)

    Gierasch, Peter J.

    2014-11-01

    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.

  15. Calibration of a Convective Parameterization Scheme in the WRF Model and its Impact on the Simulation of East Asian Summer Monsoon Precipitation

    SciTech Connect

    Yang, Ben; Zhang, Yaocun; Qian, Yun; Huang, Anning; Yan, Huiping

    2015-03-01

    Reasonably modeling the magnitude, south-north gradient and seasonal propagation of precipitation associated with the East Asian Summer Monsoon (EASM) is a challenging task in the climate community. In this study we calibrate five key parameters in the Kain-Fritsch convection scheme in the WRF model using an efficient importance-sampling algorithm to improve the EASM simulation. We also examine the impacts of the improved EASM precipitation on other physical process. Our results suggest similar model sensitivity and values of optimized parameters across years with different EASM intensities. By applying the optimal parameters, the simulated precipitation and surface energy features are generally improved. The parameters related to downdraft, entrainment coefficients and CAPE consumption time (CCT) can most sensitively affect the precipitation and atmospheric features. Larger downdraft coefficient or CCT decrease the heavy rainfall frequency, while larger entrainment coefficient delays the convection development but build up more potential for heavy rainfall events, causing a possible northward shift of rainfall distribution. The CCT is the most sensitive parameter over wet region and the downdraft parameter plays more important roles over drier northern region. Long-term simulations confirm that by using the optimized parameters the precipitation distributions are better simulated in both weak and strong EASM years. Due to more reasonable simulated precipitation condensational heating, the monsoon circulations are also improved. By using the optimized parameters the biases in the retreating (beginning) of Mei-yu (northern China rainfall) simulated by the standard WRF model are evidently reduced and the seasonal and sub-seasonal variations of the monsoon precipitation are remarkably improved.

  16. Calibration of a Convective Parameterization Scheme in the WRF Model and its Impact on the Simulation of East Asian Summer Monsoon Precipitation

    SciTech Connect

    Yang, Ben; Zhang, Yaocun; Qian, Yun; Huang, Anning; Yan, Huiping

    2015-03-26

    Reasonably modeling the magnitude, south-north gradient and seasonal propagation of precipitation associated with the East Asian Summer Monsoon (EASM) is a challenging task in the climate community. In this study we calibrate five key parameters in the Kain-Fritsch convection scheme in the WRF model using an efficient importance-sampling algorithm to improve the EASM simulation. We also examine the impacts of the improved EASM precipitation on other physical process. Our results suggest similar model sensitivity and values of optimized parameters across years with different EASM intensities. By applying the optimal parameters, the simulated precipitation and surface energy features are generally improved. The parameters related to downdraft, entrainment coefficients and CAPE consumption time (CCT) can most sensitively affect the precipitation and atmospheric features. Larger downdraft coefficient or CCT decrease the heavy rainfall frequency, while larger entrainment coefficient delays the convection development but build up more potential for heavy rainfall events, causing a possible northward shift of rainfall distribution. The CCT is the most sensitive parameter over wet region and the downdraft parameter plays more important roles over drier northern region. Long-term simulations confirm that by using the optimized parameters the precipitation distributions are better simulated in both weak and strong EASM years. Due to more reasonable simulated precipitation condensational heating, the monsoon circulations are also improved. By using the optimized parameters the biases in the retreating (beginning) of Mei-yu (northern China rainfall) simulated by the standard WRF model are evidently reduced and the seasonal and sub-seasonal variations of the monsoon precipitation are remarkably improved.

  17. Calibration of a Convective Parameterization Scheme in the WRF Model and its Impact on the Simulation of East Asian Summer Monsoon Precipitation

    DOE PAGESBeta

    Yang, Ben; Zhang, Yaocun; Qian, Yun; Huang, Anning; Yan, Huiping

    2015-03-26

    Reasonably modeling the magnitude, south-north gradient and seasonal propagation of precipitation associated with the East Asian Summer Monsoon (EASM) is a challenging task in the climate community. In this study we calibrate five key parameters in the Kain-Fritsch convection scheme in the WRF model using an efficient importance-sampling algorithm to improve the EASM simulation. We also examine the impacts of the improved EASM precipitation on other physical process. Our results suggest similar model sensitivity and values of optimized parameters across years with different EASM intensities. By applying the optimal parameters, the simulated precipitation and surface energy features are generally improved.more » The parameters related to downdraft, entrainment coefficients and CAPE consumption time (CCT) can most sensitively affect the precipitation and atmospheric features. Larger downdraft coefficient or CCT decrease the heavy rainfall frequency, while larger entrainment coefficient delays the convection development but build up more potential for heavy rainfall events, causing a possible northward shift of rainfall distribution. The CCT is the most sensitive parameter over wet region and the downdraft parameter plays more important roles over drier northern region. Long-term simulations confirm that by using the optimized parameters the precipitation distributions are better simulated in both weak and strong EASM years. Due to more reasonable simulated precipitation condensational heating, the monsoon circulations are also improved. By using the optimized parameters the biases in the retreating (beginning) of Mei-yu (northern China rainfall) simulated by the standard WRF model are evidently reduced and the seasonal and sub-seasonal variations of the monsoon precipitation are remarkably improved.« less

  18. Evaluating storm-scale groundwater recharge dynamics with coupled weather radar data and unsaturated zone modeling

    NASA Astrophysics Data System (ADS)

    Nasta, P.; Gates, J. B.; Lock, N.; Houston, A. L.

    2013-12-01

    Groundwater recharge rates through the unsaturated zone emerge from complex interactions within the soil-vegetation-atmosphere system that derive from nonlinear relationships amongst atmospheric boundary conditions, plant water use and soil hydraulic properties. While it is widely recognized that hydrologic models must capture soil water dynamics in order to provide reliable recharge estimates, information on episodic recharge generation remains uncommon, and links between storm-scale weather patterns and their influence on recharge is largely unexplored. In this study, the water balance of a heterogeneous one-dimensional soil domain (3 m deep) beneath a typical rainfed corn agro-ecosystem in eastern Nebraska was numerically simulated in HYDRUS-1D for 12 years (2001-2012) on hourly time steps in order to assess the relationships between weather events and episodic recharge generation. WSR-88D weather radar reflectivity data provided both rainfall forcing data (after estimating rain rates using the z/r ratio method) and a means of storm classification on a scale from convective to stratiform using storm boundary characteristics. Individual storm event importance to cumulative recharge generation was assessed through iterative scenario modeling (773 total simulations). Annual cumulative recharge had a mean value of 9.19 cm/yr (about 12 % of cumulative rainfall) with coefficient of variation of 73%. Simulated recharge generation events occurred only in late winter and spring, with a peak in May (about 35% of total annual recharge). Recharge generation is observed primarily in late spring and early summer because of the combination of high residual soil moisture following a winter replenishment period, heavy convective storms, and low to moderate potential evapotranspiration rates. During the growing season, high rates of root water uptake cause rapid soil water depletion, and the concurrent high potential evapotranspiration and low soil moisture prevented recharge generation until late winter, even when intense convective storms took place. For this reason, about 86% of all precipitation events produce insignificant recharge contributions. Recharge responses to individual storms were nonlinear and did not cluster well with either storm amount or storm classification type. For example, ~7% of rainfall events fall near the 1:1 rainfall/recharge line and these events represent about 37% of cumulative recharge, and individual storms accounted for up to 4% of their annual totals. However, recharge events in late winter are mainly triggered by stratiform precipitation whereas in spring they are generally generated by convective storms. This novel approach to assessing storm-scale recharge may be relevant to several current challenges in the characterization of groundwater recharge processes, including the evaluation of their spatiotemporal distributions and the impacts of climate change on groundwater.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  20. Dust Storms: Why Are Dust Storms a Concern?

    MedlinePlus

    ... blown into the air, often lifted by strong winds. Dust storms can be up to 100 miles ... Southwest during the region’s summer monsoon season, when winds shift, temperatures rise, and conditions are extremely dry. ...

  1. Convective available potential energy (CAPE) in Northern Africa and tropical Atlantic and study of its connections with rainfall in Central and West Africa during Summer 1985

    NASA Astrophysics Data System (ADS)

    Monkam, David

    In this paper, we study the distribution of the convective available potential energy (CAPE) in northern Africa and tropical Atlantic in summer. The pattern of this parameter is quite steady and presents three main zones. The first one is located between the equator and 15N-20N, with positive values of CAPE. In the second and the third zones located north of the band of latitudes 15N-20N and south of the equator, respectively, CAPE has negative values. We examined, in some details, the main tendencies of the CAPE pattern inside the first zone (CAPE >0, in general) and we compared them to the rainfall pattern. We noted that the CAPE pattern in this zone presents three regions of maximum values: west, center, and east of the zone. The maximum at east and the maximum in the center seem to be connected to the orography effects. Between 15N and 20N, the CAPE distribution is characterised by its iso-line zero. This iso-line zero seems to define the north limit of the inter tropical convergence zone (ITCZ). In fact, the position of the iso-line zero on the CAPE distribution fluctuates during summer as the position of the ITCZ so that this parameter can also be used as a parameter or an index to define the ITCZ position in northern Africa and tropical Atlantic in the summer. The patterns of the rainfall and CAPE in this zone (5N-20N) have a very good similarity. When the rainfall is very weak (<2 mm day -1) towards 12.5N-15N, the CAPE tends to become zero. The rainfall pattern presents, in general, high values towards Guinea and around Lake Chad. These regions are not very far from the maximum values of CAPE observed in different figures. The fields of correlation coefficients between the two parameters show that the rainfall and the CAPE are very well correlated around the ITCZ and towards some mountains. So, the strong values of the correlation coefficients seem to indicate that each of these two parameters is influenced by the ITCZ effects and by the orography effects.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    The 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.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

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

    SciTech Connect

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

    2011-02-13

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  8. Multilinear approach to the precipitation-lightning relationship: a case study of summer local electrical storms in the northern part of Spain during 2002-2009 period

    NASA Astrophysics Data System (ADS)

    Herrero, I.; Ezcurra, A.; Areitio, J.; Diaz-Argandoña, J.; Ibarra-Berastegi, G.; Saenz, J.

    2013-11-01

    Storms developed under local instability conditions are studied in the Spanish Basque region with the aim of establishing precipitation-lightning relationships. Those situations may produce, in some cases, flash flood. Data used correspond to daily rain depth (mm) and the number of CG flashes in the area. Rain and lightning are found to be weakly correlated on a daily basis, a fact that seems related to the existence of opposite gradients in their geographical distribution. Rain anomalies, defined as the difference between observed and estimated rain depth based on CG flashes, are analysed by PCA method. Results show a first EOF explaining 50% of the variability that linearly relates the rain anomalies observed each day and that confirms their spatial structure. Based on those results, a multilinear expression has been developed to estimate the rain accumulated daily in the network based on the CG flashes registered in the area. Moreover, accumulates and maximum values of rain are found to be strongly correlated, therefore making the multilinear expression a useful tool to estimate maximum precipitation during those kind of storms.

  9. 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)

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

    1981-01-01

    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.

  10. Modeling haboob dust storms in large-scale weather and climate models

    NASA Astrophysics Data System (ADS)

    Pantillon, Florian; Knippertz, Peter; Marsham, John H.; Panitz, Hans-Jürgen; Bischoff-Gauss, Ingeborg

    2016-03-01

    Recent field campaigns have shown that haboob dust storms, formed by convective cold pool outflows, contribute a significant fraction of dust uplift over the Sahara and Sahel in summer. However, in situ observations are sparse and haboobs are frequently concealed by clouds in satellite imagery. Furthermore, most large-scale weather and climate models lack haboobs, because they do not explicitly represent convection. Here a 1 year long model run with explicit representation of convection delivers the first full seasonal cycle of haboobs over northern Africa. Using conservative estimates, the model suggests that haboobs contribute one fifth of the annual dust-generating winds over northern Africa, one fourth between May and October, and one third over the western Sahel during this season. A simple parameterization of haboobs has recently been developed for models with parameterized convection, based on the downdraft mass flux of convection schemes. It is applied here to two model runs with different horizontal resolutions and assessed against the explicit run. The parameterization succeeds in capturing the geographical distribution of haboobs and their seasonal cycle over the Sahara and Sahel. It can be tuned to the different horizontal resolutions, and different formulations are discussed with respect to the frequency of extreme events. The results show that the parameterization is reliable and may solve a major and long-standing issue in simulating dust storms in large-scale weather and climate models.

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

    NASA Astrophysics Data System (ADS)

    Lee, Craig M.; Brink, Kenneth H.

    2010-08-01

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

  12. 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)

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

    2014-10-01

    Storm-enhanced 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.

  13. A long-lived mesoscale convective complex. I - The mountain-generated component

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    The South Park Area Cumulus Experiment (SPACE) was conducted during the summer of 1977, and takes into account meteorological developments in a broad, elevated basin called South Park, which is located northeast of Colorado Springs, Colorado. The experiment was designed to investigate the organization of the mesoscale and storm-scale systems in detail over South Park. Many of the convective storms which were observed in the developing stages over South Park participated in the genesis of mesoscale convective complexes (MCCs) on the meso-alpha-scale. The present investigation is concerned with the evolution of the second MCC of this episode, which matured on the evening of August 4, 1977. Attention is given to the events from the preconvective stage early on August 4 to the incipient MCC stage in the early evening.

  14. Characterizing the Relationships Among Lightning and Storm Parameters: Lightning as a Proxy Variable

    NASA Technical Reports Server (NTRS)

    Goodman, S. J.; Raghavan, R.; William, E.; Weber, M.; Boldi, B.; Matlin, A.; Wolfson, M.; Hodanish, S.; Sharp. D.

    1997-01-01

    We have gained important insights from prior studies that have suggested relationships between lightning and storm growth, decay, convective rain flux, vertical distribution of storm mass and echo volume in the region, and storm energetics. A study was initiated in the Summer of 1996 to determine how total (in-cloud plus ground) lightning observations might provide added knowledge to the forecaster in the determination and identification of severe thunderstorms and weather hazards in real-time. The Melbourne Weather Office was selected as a primary site to conduct this study because Melbourne is the only site in the world with continuous and open access to total lightning (LDAR) data and a Doppler (WSR-88D) radar. A Lightning Imaging Sensor Data Applications Demonstration (LISDAD) system was integrated into the forecaster's workstation during the Summer 1996 to allow the forecaster to interact in real-time with the multi-sensor data being displayed. LISDAD currently ingests LDAR data, the cloud-to-ground National Lightning Detection Network (NLDN) data, and the Melbourne radar data in f real-time. The interactive features provide the duty forecaster the ability to perform quick diagnostics on storm cells of interest. Upon selection of a storm cell, a pop-up box appears displaying the time-history of various storm parameters (e.g., maximum radar reflectivity, height of maximum reflectivity, echo-top height, NLDN and LDAR lightning flash rates, storm-based vertically integrated liquid water content). This product is archived to aid on detailed post-analysis.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  17. Gravity wave initiated convection

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1990-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  19. Sensitivity of RegCM4.3 two convection schemes on Indian summer monsoon for the South Asia CORDEX domain

    NASA Astrophysics Data System (ADS)

    Mamgain, Ashu; Mariotti, Laura; Coppola, Erika; Giorgi, Filippo; Dash, Sushil Kumar

    2013-04-01

    Regional climate models can be used to examine the impact of global warming at the regional level for the possible emission scenarios. According to IPCC AR4, a number of studies noticed large inter model differences leading to large uncertainties in the projected future changes in different aspects of monsoon rainfall. The aim of this study to understand the different response of similarly forced model RegCM4.3 with different convection scheme over the Ocean. In this study, RegCM4.3 is used to generate the climate scenarios for South Asia CORDEX domain using boundary forcing of global coupled climate models GFDL-ESM2M and MPI-ESM-MR in control runs and two emission scenarios RCP4.5 and RCP8.5 obtained from CMIP5 archive. Emanuel convective parameterization scheme has been used over the land in all the experiments. Over the Ocean, experiments are designed using both Emanual and Grell convection schemes. Rest of the model configuration is based on the different sensitivity experiments conducted to reduce the model temperature and precipitation biases. The model has been integrated at 50km resolution starting from the initial condition of 1st Jan 1970 and the climate simulation continued till 1st Jan 2100. Results indicate that all India JJAS mean temperature change is consistent with clear projection of warming, whereas the projected JJAS precipitation change shows large spread and uncertainty in trends. Even the similar forcing experiments with difference only in the convective scheme over ocean show large difference in their projected precipitation. Climatology of JJAS precipitation over Indian land and low level westerlies for the historical period (1979-2005) is well represented. However, there are differences in the precipitation distribution at regional level within the experiments mainly over the Northwest and southern part of Peninsular India. In case of Emanuel over ocean, enhanced convection over Indian land is mainly associated with the weak westerlies over the Bay of Bengal. The positive anomalies of westerly jet are captured over the Arabian Sea in both the cases where Grell convection over ocean is used in RegCM4.3. Grell scheme over ocean has significantly improved the pattern of westerly flow in RegCM4.3 simulations forced with the considered GCMs.

  20. Future intensification of hourly rainfall in a convection permitting climate model

    NASA Astrophysics Data System (ADS)

    Kendon, Elizabeth; Roberts, Nigel; Fowler, Hayley; Chan, Steven; Roberts, Malcolm; Senior, Cath

    2014-05-01

    The first climate change experiments with a convection-permitting model have been carried out for a region of the UK. This (1.5km) model gives a much more realistic representation of the characteristics of hourly rainfall compared to a coarser resolution (12km) regional climate model (RCM), giving us greater confidence in its ability to reliably project future changes. Both models show very similar changes in hourly rainfall in winter, but quite different changes in summer. The 1.5km-RCM shows evidence of an intensification of short-duration rain in summer not seen in the 12km-RCM. This leads to significantly more events exceeding high thresholds indicative of likely flash flooding. Results here suggest representation of the local storm dynamics is essential for predicting future change in convective extremes.

  1. Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Gonzalez, Walter D.

    1998-01-01

    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.

  2. Empirical Data Fusion for Convective Weather Hazard Nowcasting

    NASA Astrophysics Data System (ADS)

    Williams, J.; Ahijevych, D.; Steiner, M.; Dettling, S.

    2009-09-01

    This paper describes a statistical analysis approach to developing an automated convective weather hazard nowcast system suitable for use by aviation users in strategic route planning and air traffic management. The analysis makes use of numerical weather prediction model fields and radar, satellite, and lightning observations and derived features along with observed thunderstorm evolution data, which are aligned using radar-derived motion vectors. Using a dataset collected during the summers of 2007 and 2008 over the eastern U.S., the predictive contributions of the various potential predictor fields are analyzed for various spatial scales, lead-times and scenarios using a technique called random forests (RFs). A minimal, skillful set of predictors is selected for each scenario requiring distinct forecast logic, and RFs are used to construct an empirical probabilistic model for each. The resulting data fusion system, which ran in real-time at the National Center for Atmospheric Research during the summer of 2009, produces probabilistic and deterministic nowcasts of the convective weather hazard and assessments of the prediction uncertainty. The nowcasts' performance and results for several case studies are presented to demonstrate the value of this approach. This research has been funded by the U.S. Federal Aviation Administration to support the development of the Consolidated Storm Prediction for Aviation (CoSPA) system, which is intended to provide convective hazard nowcasts and forecasts for the U.S. Next Generation Air Transportation System (NextGen).

  3. Magnetic storms

    NASA Astrophysics Data System (ADS)

    Tsurutani, Bruce T.; Gonzalez, Walter D.; Kamide, Yohsuke

    This talk provides a brief summary of the first conference devoted entirely to magnetic storms. The conference was held in Pasadena, California, at the Jet Propulsion Laboratory, 12-16 February 1996. Topics covered the relevant time-varying phenomena at the sun/corona, propagation of these structures through interplanetary space, the response of the magnetosphere from its 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. A complementary summary is provided by Gonzalez et al. in EOS, 1996. The full set of review articles will be published in an AGU monograph and many of the contributed articles will appear in a special section of the Journal of Geophysical Research, Space Physics.

  4. A Linearized Convective Overturning Model for Prediction of Thunderstorm Movement.

    NASA Astrophysics Data System (ADS)

    Marroquin, Adrian; Raymond, David J.

    1982-01-01

    A linearized model of convective overturning in shear for prediction of storm propagation is presented. Good correspondence between the model and observation is found for a number of case studies of real storms. Supercell storms, however, are an exception-the tendency to move to the right of the mean winds is not reproduced.

  5. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    article title: Massive Dust Storm over Australia View ... winds and dry conditions caused a massive blanket of dust from Australia's Outback to spread eastward across Queensland and New ... data were obtained from the NASA Langley Research Center Atmospheric Science Data Center in Hampton, VA. Image credit: ...

  6. A Double-Moment Multiple-Phase Four-Class Bulk Ice Scheme. Part II: Simulations of Convective Storms in Different Large-Scale Environments and Comparisons with other Bulk Parameterizations.

    NASA Astrophysics Data System (ADS)

    Schoenberg Ferrier, Brad; Tao, Wei-Kuo; Simpson, Joanne

    1995-04-01

    Part I of this study described a detailed four-class bulk ice scheme (4ICE) developed to simulate the hydro-meteor profiles of convective and stratiform precipitation associated with mesoscale convective systems. In Part II, the 4ICE scheme is incorporated into the Goddard Cumulus Ensemble (GCE) model and applied without any `tuning' to two squall lines occurring in widely different environments, namely, one over the `Pica) ocean in the Global Atmospheric Research Program's (GARP) Atlantic Tropical Experiment (GATE) and the other over a midlatitude continent in the Cooperative Huntsville Meteorological Experiment (COHMEX). Comparisons were made both with earlier three-class ice formulations and with observations. In both cases, the 4ICE scheme interacted with the dynamics so as to resemble the observations much more closely than did the model runs with either of the three-class ice parameterizations. The following features were well simulated in the COHMEX case: a lack of stratiform rain at the surface ahead of the storm, reflectivity maxima near 60 dBZ in the vicinity of the melting level, and intense radar echoes up to near the tropopause. These features were in strong contrast with the GATE simulation, which showed extensive trailing stratiform precipitation containing a horizontally oriented radar bright band. Peak reflectivities were below the melting level, rarely exceeding 50 dBz, with a steady decrease in reflectivity with height above. With the other bulk formulations, the large stratiform rain areas were not reproduced in the GATE conditions.The microphysical structure of the model clouds in both environments were more realistic than that of earlier modeling efforts. Number concentrations of ice of O(100 L1) occurred above 6 km in the GATE model clouds as a result of ice enhancement and rime splintering in the 4ICE runs. These processes were more effective in the GATE simulation, because near the freezing level the weaker updrafts were comparable in magnitude to the fall speeds of newly frozen drops. Many of the ice crystals initiated at relatively warm temperatures (above 15°C) grew rapidly by deposition into sizes large enough to be converted to snow. In contrast, in the more intense COHMEX updrafts, very large numbers of small ice crystals were initiated at colder temperatures (below 15°C) by nucleation and stochastic freezing of droplets, such that relatively few ice crystals grew by deposition to sizes large enough to be converted to snow. In addition, the large number of frozen drops of O(5 L1) in the 4ICE run am consistent with airborne microphysical data in intense COHMEX updrafts.Numerous sensitivity experiments were made with the four-class and three-class ice schemes, varying fall speed relationships, particle characteristics, and ice collection efficiencies. These tests provide strong support to the conclusion that the 4ICE scheme gives improved resemblance to observations despite present uncertainties in a number of important microphysical parameters.

  7. Weak linkage between the heaviest rainfall and tallest storms

    NASA Astrophysics Data System (ADS)

    Hamada, Atsushi; Takayabu, Yukari N.; Liu, Chuntao; Zipser, Edward J.

    2015-02-01

    Conventionally, the heaviest rainfall has been linked to the tallest, most intense convective storms. However, the global picture of the linkage between extreme rainfall and convection remains unclear. Here we analyse an 11-year record of spaceborne precipitation radar observations and establish that a relatively small fraction of extreme convective events produces extreme rainfall rates in any region of the tropics and subtropics. Robust differences between extreme rainfall and convective events are found in the rainfall characteristics and environmental conditions, irrespective of region; most extreme rainfall events are characterized by less intense convection with intense radar echoes not extending to extremely high altitudes. Rainfall characteristics and environmental conditions both indicate the importance of warm-rain processes in producing extreme rainfall rates. Our results demonstrate that, even in regions where severe convective storms are representative extreme weather events, the heaviest rainfall events are mostly associated with less intense convection.

  8. Weak linkage between the heaviest rainfall and tallest storms

    PubMed Central

    Hamada, Atsushi; Takayabu, Yukari N.; Liu, Chuntao; Zipser, Edward J.

    2015-01-01

    Conventionally, the heaviest rainfall has been linked to the tallest, most intense convective storms. However, the global picture of the linkage between extreme rainfall and convection remains unclear. Here we analyse an 11-year record of spaceborne precipitation radar observations and establish that a relatively small fraction of extreme convective events produces extreme rainfall rates in any region of the tropics and subtropics. Robust differences between extreme rainfall and convective events are found in the rainfall characteristics and environmental conditions, irrespective of region; most extreme rainfall events are characterized by less intense convection with intense radar echoes not extending to extremely high altitudes. Rainfall characteristics and environmental conditions both indicate the importance of warm-rain processes in producing extreme rainfall rates. Our results demonstrate that, even in regions where severe convective storms are representative extreme weather events, the heaviest rainfall events are mostly associated with less intense convection. PMID:25708295

  9. Weak linkage between the heaviest rainfall and tallest storms.

    PubMed

    Hamada, Atsushi; Takayabu, Yukari N; Liu, Chuntao; Zipser, Edward J

    2015-01-01

    Conventionally, the heaviest rainfall has been linked to the tallest, most intense convective storms. However, the global picture of the linkage between extreme rainfall and convection remains unclear. Here we analyse an 11-year record of spaceborne precipitation radar observations and establish that a relatively small fraction of extreme convective events produces extreme rainfall rates in any region of the tropics and subtropics. Robust differences between extreme rainfall and convective events are found in the rainfall characteristics and environmental conditions, irrespective of region; most extreme rainfall events are characterized by less intense convection with intense radar echoes not extending to extremely high altitudes. Rainfall characteristics and environmental conditions both indicate the importance of warm-rain processes in producing extreme rainfall rates. Our results demonstrate that, even in regions where severe convective storms are representative extreme weather events, the heaviest rainfall events are mostly associated with less intense convection. PMID:25708295

  10. Daytime identification of summer hailstorm cells from MSG data

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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 %.

  11. NASA's GPM Gets a Look at Newborn, Late Season Eastern Pacific Tropical Storm Sandra - Duration: 15 seconds.

    NASA Video Gallery

    On Nov. 24, GPM saw intense convective storms south of the tropical storm's center of circulation were dropping rain at a rate of over 80 mm (3.1 inches) per hour. Cloud tops reached heights above ...

  12. Characteristics of ionospheric storms in East Asia

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Wang, Guojun; Shi, Jiankui

       The ionosphere experiences intense response during the geomagnetic storm and it varies with latitude and longitude. The DPS-4 digisonde measurements and GPS-TEC data of ionospheric stations located at different latitudes in the longitudinal sector of 90-130E during 2002 to 2012 were analyzed to investigate the ionospheric effects in the different latitude of East Asia during geomagnetic storm. About 70 geomagnetic storms are selected according to the Dst index and observed data and they are in different seasons and different solar activity levels. A few quiet days’ averages of data before geomagnetic storm were used as the undisturbed level. Results show that for the middle and high latitude, the short-lived positive disturbance associated with the initial phase of the every storm was observed in each season and then the disturbances were negative till the termination of storm. At the low latitude, storm-time disturbances of foF2 have obvious diurnal, seasonal and solar cycle characteristics. Generally, geomagnetic activity will cause foF2 to increase at daytime and decrease at nighttime except for the summer in low solar activity period. The intensity of response of foF2 is stronger at nighttime than that at daytime. The negative ionospheric storm effect is the strongest in summer and the positive ionospheric storm effect is the strongest in winter. In high solar activity period, the diurnal variation of the response of foF2 is very pronounced in each season, and the strong ionospheric response can last several days. In low solar activity period, ionospheric response has very pronounced diurnal variation in winter only. It’s notable that geomagnetic activities occurred at local time nighttime can cause stronger and longer responses of foF2 at the low latitude. All in all, the obvious negative phase ionospheric storms often occurred at the low latitude. Moreover a notable phenomenon was observed for the low latitude, there are the intensive oscillations of foF2 occurring during the main storm phase of enhanced storm in Hainan, and it occurred in the morning generally. For the TEC data, strong disturbances can be observed simultaneously from high latitude to low latitude during the main phase of some storms. Generally strong/weak storms can cause the negative/positive phase storms of TEC in the low latitude and which are obvious in the daytime for the summer and winter and in the period from noon to midnight for the equinox. The differences of the responses of foF2 and TEC are also investigated.

  13. The Influence of Synoptic Meteorology on Convective Boundary Layer Characteristics and the Observed Chemical Response During PROPHET 2000 and 2001 Summer Intensives

    NASA Astrophysics Data System (ADS)

    Lilly, M. A.; Moody, J. L.; Carroll, M.; Brown, W. O.; Cohn, S. A.

    2002-12-01

    PROPHET conducted atmospheric chemistry intensives that were coordinated with continuous measurements of the atmospheric boundary layer at the University of Michigan Biological Station (UMBS) during July and August of 2000 and 2001. Observations of ozone and trace gas precursors were made on a 31-meter tower within a mixed hardwood forest. A National Center for Atmospheric Research (NCAR) integrated sounding system (915-MHz Doppler wind profiler, radio acoustic sounder, surface meteorological tower, and rawinsonde system) was deployed in a nearby clearing. This facility provided detailed measurements of atmospheric boundary layer structure. The site is located at the northern tip of the Michigan's lower peninsula. Typically, a contaminated maritime-subtropical air mass lies to the south, while a relatively clean continental-polar air mass lies to the north, resulting in two distinct synoptic transport regimes. Published work, based on analyses of back trajectories and 1998 chemical data, has shown the influence of air mass origin on trace gas mixing ratios and the same trends are observed in 2000 and 2001 chemical data. Besides directly affecting the chemistry observed at the site, the large-scale synoptic meteorology has a major influence on convective boundary layer (CBL) characteristics. CBL data were obtained from the range corrected signal-to-noise ratio, derived from the Doppler spectra measured by the wind profiler. Distinct differences between CBL characteristics, such as growth rates, time period of maximum growth, average height throughout evolution, and maximum height, are illustrated for differing synoptic patterns. Typically, dry northerly flow results when UMBS is positioned on the leading edge of surface anticyclones moving out of Canada after frontal passages. The dry air mass accompanied with relatively clear skies allows intense solar radiation to go directly into surface heating; the result is rapid CBL development. By contrast, warm, moist air from the south is advected toward the region when the UMBS sits on the back of surface anticyclones ahead of approaching frontal boundaries. This transport regime characteristically consists of air with high moisture content and an early morning low stratus deck giving way to hazy afternoon skies. Surface values of specific humidity throughout 2001 were nearly 4 g/kg higher under southerly flow. Solar radiation is partitioned into evaporating moisture and surface heating, which results in slower CBL growth. During PROPHET 2001 mean CBL heights were 200 meters lower under southerly flow when the site was located on the back of a surface anticyclone. This analysis quantifies the influence of variation in boundary layer characteristics on PROPHET chemical observations.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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 So 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 Paraba and So 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.

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

    NASA Astrophysics Data System (ADS)

    Buresova, D.; McKinnell, L.-A.; Sindelarova, T.; De La Morena, B. A.

    2010-10-01

    This paper presents results from the Storm-Time Ionospheric Correction Model (STORM) validation for selected Northern and Southern Hemisphere middle latitude locations. The created database incorporated 65 strong-to-severe geomagnetic storms, which occurred within the period 1995-2007. This validation included data from some ionospheric stations (e.g., Pruhonice, El Arenosillo) that were not considered in the development or previous validations 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 were compared with the predicted IRI 2007 foF2 with the STORM model option activated. To perform a detailed comparison between observed values, medians and predicted foF2 values the correlation coefficient, the root-mean-square error (RMSE), and the percentage improvement were 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 the changeover of the different storm phases is reproduced with less accuracy. The STORM model corrections are less efficient for lower-middle latitudes and severe geomagnetic storms.

  16. Storm-time Injection of Plasma Sheet Electrons into the Radiation Belt During the March~31, 2001 Geomagnetic StormOuter

    NASA Astrophysics Data System (ADS)

    Elkington, S. R.; Baker, D. N.; Li, X.; Hudson, M. K.; Wiltberger, M. J.

    2001-12-01

    A fundamental problem in understanding the physics of the outer radiation belts is the very origin of the energetic particles comprising them [Li et al., GRL~24, 923, 1997]. Several sources have been suggested, e.g., injection of particles from the cusp [Sheldon et al., GRL 25, 1825, 1998], local heating of inner magnetospheric plasmas [e.g. Summers & Ma, JGR 105, 15887, 2000], or through the transport of plasma sheet particles into the stable trapping region of the inner magnetosphere via convective or substorm injection. In general, the latter may occur when time-varying electric and magnetic fields alter the position of the Alfvén layer, the energy- and field-dependent separatrix between those particles whose gradient-curvature drift keeps them on closed orbits within the magnetosphere, and those particles whose drift paths intersect the magnetopause. In this work, we use global MHD simulations of the March~31, 2001 magnetic storm to investigate the transport of energetic (keV) electrons from the plasma sheet into the stable trapping region. We examine trapping efficiency both under the influence of strong, time-varying magnetospheric convection, such as characterized the main phase of this storm, as well as during periods of substantial magnetotail reconfiguration, such as may be associated with the dramatic 0630 substorm observed during this event.

  17. Influence of open water bodies on the generation of summertime convection over the Canadian Prairies

    NASA Astrophysics Data System (ADS)

    Joshi, D.; Bélair, S.; Carrera, M. L.; Leroyer, S.

    2014-12-01

    There are still numerous water features on the Canadian landscape that are not monitored. Specifically, there are landscape features (e.g. the prairies and Canadian shield regions of North America) that are ephemeral in nature and have a significant influence on convective storm generation and local weather patterns through turbulent exchanges of sensible and latent heat between land and the atmosphere. In this study we perform a series of numerical experiments with the GEM (Global Environmental Multiscale model) model at 2.5 km resolution to examine the sensitivity of the atmospheric boundary layer to the presence of open water bodies. At present the land-water fraction in the GEM model is specified by means of static geophysical databases which do not change annually. Uncertainty is introduced into this land-water fraction and the sensitivity of the resulting soil moisture and precipitation is quantified for a series of convective precipitation events over Alberta for the summer 2014 period.

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

    NASA Astrophysics Data System (ADS)

    shalaby, ahmed

    2014-05-01

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

  19. Characterization of Mediterranean hail-bearing storms using an operational polarimetric X-band radar

    NASA Astrophysics Data System (ADS)

    Vulpiani, G.; Baldini, L.; Roberto, N.

    2015-07-01

    This work documents the fruitul use of X-band radar observations for the monitoring of severe storms in an operational framework. More specifically, a couple of severe hail-bearing Mediterranean storms occurred in 2013 in southern Italy, flooding two important cities of Sicily, are described in terms of their polarimetric radar signatures and retrieved rainfall fields. It is used the X-band dual-polarization radar operating inside the Catania airport (Sicily, Italy), managed by the Italian Department of Civil Protection. A suitable processing is applied to X-band radar measurements. The crucial procedural step relies on the differential phase processing based on an iterative approach that uses a very short-length (1 km) moving window allowing to properly catch the observed high radial gradients of the differential phase. The parameterization of the attenuation correction algorithm, which use the reconstructed differential phase shift, is derived from electromagnetic simulations based on 3 years of DSD observations collected in Rome (Italy). A Fuzzy Logic hydrometeor classification algorithm was also adopted to support the analysis of the storm characteristics. The precipitation fields amount were reconstructed using a combined polarimetric rainfall algorithm based on reflectivity and specific differential phase. The first considered storm was observed on the 21 February, when a winter convective system, originated in the Tyrrhenian sea, hit only marginally the central-eastern coastline of Sicily causing the flash-flood of Catania. Due to the optimal radar location (the system is located at just few kilometers from the city center), it was possible to well retrieve the storm characteristics, including the amount of rainfall field at ground. Extemporaneous signal extinction, caused by close-range hail core causing significant differential phase shift in very short range path, is documented. The second storm, occurred on 21 August 2013, is a summer mesoscale convective system originated by the temperature gradient between sea and land surface, lasted a few hours and eventually flooded the city of Siracusa. The undergoing physical process, including the storm dynamics, is inferred by analysing the vertical sections of the polarimetric radar measurements. The high registered precipitation amount was fairly well reconstructed even though with a trend to underestimation at increasing distances. Several episodes of signal extinction clearly manifested during the mature stage of the observed supercell.

  20. Characterization of Mediterranean hail-bearing storms using an operational polarimetric X-band radar

    NASA Astrophysics Data System (ADS)

    Vulpiani, G.; Baldini, L.; Roberto, N.

    2015-11-01

    This work documents the effective use of X-band radar observations for monitoring severe storms in an operational framework. Two severe hail-bearing Mediterranean storms that occurred in 2013 in southern Italy, flooding two important Sicilian cities, are described in terms of their polarimetric radar signatures and retrieved rainfall fields. The X-band dual-polarization radar operating inside the Catania airport (Sicily, Italy), managed by the Italian Department of Civil Protection, is considered here. A suitable processing is applied to X-band radar measurements. The crucial procedural step relies on the differential phase processing, being preparatory for attenuation correction and rainfall estimation. It is based on an iterative approach that uses a very short-length (1 km) moving window, allowing proper capture of the observed high radial gradients of the differential phase. The parameterization of the attenuation correction algorithm, which uses the reconstructed differential phase shift, is derived from electromagnetic simulations based on 3 years of drop size distribution (DSD) observations collected in Rome (Italy). A fuzzy logic hydrometeor classification algorithm was also adopted to support the analysis of the storm characteristics. The precipitation field amounts were reconstructed using a combined polarimetric rainfall algorithm based on reflectivity and specific differential phase. The first storm was observed on 21 February when a winter convective system that originated in the Tyrrhenian Sea, marginally hit the central-eastern coastline of Sicily, causing a flash flood in Catania. Due to an optimal location (the system is located a few kilometers from the city center), it was possible to retrieve the storm characteristics fairly well, including the amount of rainfall field at the ground. Extemporaneous signal extinction, caused by close-range hail core causing significant differential phase shift in a very short-range path, is documented. The second storm, on 21 August 2013, was a summer mesoscale convective system that originated from a Mediterranean low pressure system lasting a few hours that eventually flooded the city of Syracuse. The undergoing physical process, including the storm dynamics, is inferred by analyzing the vertical sections of the polarimetric radar measurements. The high registered amount of precipitation was fairly well reconstructed, although with a trend toward underestimation at increasing distances. Several episodes of signal extinction were clearly manifested during the mature stage of the observed supercells.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  2. Initiation of deep convection along boundary layer convergence lines in a semitropical environment

    SciTech Connect

    Fankhauser, J.C.; Crook, N.A.; Tuttle, J.; Miller, L.J.; Wade, C.G.

    1995-02-01

    The initiation of deep convection through forcing along boundary layer convergence lines is examined using observations from the Convection and Precipitation/Electrification (CaPE) Experiment conducted in east-central Florida during the summer of 1991. The study is concerned with the evolution and interaction of two converging air masses that were initially separated by an intervening boundary layer characterized by neutral stability and horizontal convective rolls. As anticipated, major thunderstorms erupt when the east coast breeze eventually collides with thunderstorm outflows from the west, but unexpected convection takes place prior to their merger along a well-defined confluence zone associated with a persistent quasi-stationary roll vortex signature. In this study, complementary interactions between roll vortex convergence lines and the sea-breeze front are not sufficient to trigger deep convection. However, organized convergence along the eastward-spreading thunderstorm outflows did interact periodically with roll vortex convergence maxima to initiate a new series of new storms. Results from two-dimensional numerical model simulations replicate many of the observed boundary layer features. Surface heating produces circulations similar to sea-breeze frontal zones that appear near the coastlines and progress steadily toward each other as the interior boundary layer deepens. Vertical velocity maxima develop over the associated convergence zones, but weaker periodic maxima also occur within the interior air mass at intervals similar to the spacing of observed horizontal roll vortices.

  3. Preliminary calculations of average storm duration and seasonal precipitation rates for the northeast sector of the united states

    NASA Astrophysics Data System (ADS)

    Thorp, John M.; Scott, Bryan C.

    Regional and seasonal averages of storm duration and precipitation rates are needed as input variables in models aimed at describing precipitation processes relating to acid rain and other problems. Hourly precipitation data for 77 first order weather stations were used to calculate the summer and winter regional average storm duration and average precipitation rates over the northeastern United States. Average storm duration for summer (June-July-August), and winter (December-January-February) seasons considered periods of up to three dry hours in summer storms, and up to 6 dry hours in winter storms to be part of the same storm. Thus, each storm consisted of one or more precipitation periods. The average precipitation event rates for summer and winter storms were calculated. By considering storm duration on an hourly basis, the 3-h summer storm was found to contribute the greatest fraction to total summer precipitation. Similarly, the 26-h winter storm was found to contribute the greatest fraction to winter precipitation. The summer storms typically consisted of one rain event lasting about three hours with rain rates averaging ~ 2.5 mm h -1. The 25-h winter storm averaged about 3 precipitation periods (or rain bands). Each period lasted about seven hours and had an average precipitation rate of 1.0 mmh -1.

  4. Relationship between convective precipitation and lightning activity using radar quantitative precipitation estimates and total lightning data

    NASA Astrophysics Data System (ADS)

    Pineda, N.; Rigo, T.; Bech, J.; Argemí, O.

    2009-09-01

    Thunderstorms can be characterized by both rainfall and lightning. The relationship between convective precipitation and lightning activity may be used as an indicator of the rainfall regime. Besides, a better knowledge of local thunderstorm phenomenology can be very useful to assess weather surveillance tasks. Two types of approach can be distinguished in the bibliography when analyzing the rainfall and lightning activity. On one hand, rain yields (ratio of rain mass to cloud-to-ground flash over a common area) calculated for long temporal and spatial domains and using rain-gauge records to estimate the amounts of precipitation. On the other hand, a case-by-case approach has been used in many studies to analyze the relationship between convective precipitation and lightning in individual storms, using weather radar data to estimate rainfall volumes. Considering a local thunderstorm case study approach, the relation between rainfall and lightning is usually quantified as the Rainfall-Lightning ratio (RLR). This ratio estimates the convective rainfall volume per lightning flash. Intense storms tend to produce lower RLR values than moderate storms, but the range of RLR found in diverse studies is quite wide. This relationship depends on thunderstorm type, local climatology, convective regime, type of lightning flashes considered, oceanic and continental storms, etc. The objective of this paper is to analyze the relationship between convective precipitation and lightning in a case-by-case approach, by means of daily radar-derived quantitative precipitation estimates (QPE) and total lightning data, obtained from observations of the Servei Meteorològic de Catalunya remote sensing systems, which covers an area of approximately 50000 km2 in the NE of the Iberian Peninsula. The analyzed dataset is composed by 45 thunderstorm days from April to October 2008. A good daily correlation has been found between the radar QPE and the CG flash counts (best linear fit with a R^2=0.74). The daily RLR found has a mean value of 86 10^3m3 rainfall volume per CG flash. The daily range of variation is quite wide, as it goes from 19 to 222 10^3m3 per CG flash. This variation has a seasonal component, related to changes in the convective regime. Summer days (July to middle September) had a mean RLR of 57 10^3m3 rainfall volume per CG flash, while from middle September to the end of October the rainfall volume per CG flash doubles (mean of 125 10^3m3 per CG flash).

  5. 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...

  6. The Dynamics of Titan's Convective Clouds

    NASA Astrophysics Data System (ADS)

    Rafkin, S. C.

    2012-12-01

    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.

  7. 75 FR 17132 - Intent To Prepare a Draft Environmental Impact Statement for Hurricane and Storm Damage Reduction...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-05

    ... Hurricane and Storm Damage Reduction for South Ponte Vedra Beach, Vilano Beach, and Summer Haven Beach... storm damage reduction (HSDR), and related purposes to the shores of St. Johns County, Florida....

  8. Report of convective phenomena team

    NASA Technical Reports Server (NTRS)

    Orville, H.; Koenig, R.; Miller, J.; Telford, J.; Jones, B.; Alger, G.; Lee, R.; Boudle, D.

    1980-01-01

    A group meeting was assembled to focus on the planning of specific experiments, to establish some priorities, identify interested scientists who would like to participate, establish any special requirements, make recommendations on data processing, and to prepare flight plan outlines. Since the number of convective storms in the CCOPE (Cooperative Convective Precipitation Experiment) field experiment area are limited to only a few days during the operational time period the flight plans must be designed with a hierarchy of abort experiments so that the easily identified and lowest probability events should take priority until their quota is filled.

  9. Rocket dust storms and detached layers in the Martian atmosphere

    NASA Astrophysics Data System (ADS)

    Spiga, A.; Faure, J.; Madeleine, J.; Maattanen, A. E.; Forget, F.

    2012-12-01

    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 onboard 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 onboard Mars Global Surveyor and Mars Reconnaissance Orbiter. Detached layers are stable over several days owing to nighttime sedimentation being unable to counteract daytime convective transport, and to the resupply of convective energy at sunrise. The peak activity of rocket dust storms is expected in low-latitude regions at clear season, which accounts for the high-altitude tropical dust maximum unveiled by Mars Climate Sounder. Our findings on dust-driven deep convection have strong implications for the Martian dust cycle, thermal structure, atmospheric dynamics, cloud microphysics, chemistry, and robotic and human exploration.ensity-scaled dust optical depth at local times 1400 1600 and 1800 (lat 2.5°S, Ls 135°) hortwave heating rate at local time 1500 and latitude 2.5°S.

  10. Research Opportunities at Storm Peak Laboratory

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  11. Arctic Summer Ice Processes

    NASA Technical Reports Server (NTRS)

    Holt, Benjamin

    1999-01-01

    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.

  12. Storm Track Response to Perturbations in Climate

    NASA Astrophysics Data System (ADS)

    Mbengue, Cheikh Oumar

    This thesis advances our understanding of midlatitude storm tracks and how they respond to perturbations in the climate system. The midlatitude storm tracks are regions of maximal turbulent kinetic energy in the atmosphere. Through them, the bulk of the atmospheric transport of energy, water vapor, and angular momentum occurs in midlatitudes. Therefore, they are important regulators of climate, controlling basic features such as the distribution of surface temperatures, precipitation, and winds in midlatitudes. Storm tracks are robustly projected to shift poleward in global-warming simulations with current climate models. Yet the reasons for this shift have remained unclear. Here we show that this shift occurs even in extremely idealized (but still three-dimensional) simulations of dry atmospheres. We use these simulations to develop an understanding of the processes responsible for the shift and develop a conceptual model that accounts for it. We demonstrate that changes in the convective static stability in the deep tropics alone can drive remote shifts in the midlatitude storm tracks. Through simulations with a dry idealized general circulation model (GCM), midlatitude storm tracks are shown to be located where the mean available potential energy (MAPE, a measure of the potential energy available to be converted into kinetic energy) is maximal. As the climate varies, even if only driven by tropical static stability changes, the MAPE maximum shifts primarily because of shifts of the maximum of near-surface meridional temperature gradients. The temperature gradients shift in response to changes in the width of the tropical Hadley circulation, whose width is affected by the tropical static stability. Storm tracks generally shift in tandem with shifts of the subtropical terminus of the Hadley circulation. We develop a one-dimensional diffusive energy-balance model that links changes in the Hadley circulation to midlatitude temperature gradients and so to the storm tracks. It is the first conceptual model to incorporate a dynamical coupling between the tropical Hadley circulation and midlatitude turbulent energy transport. Numerical and analytical solutions of the model elucidate the circumstances of when and how the storm tracks shift in tandem with the terminus of the Hadley circulation. They illustrate how an increase of only the convective static stability in the deep tropics can lead to an expansion of the Hadley circulation and a poleward shift of storm tracks. The simulations with the idealized GCM and the conceptual energy-balance model demonstrate a clear link between Hadley circulation dynamics and midlatitude storm track position. With the help of the hierarchy of models presented in this thesis, we obtain a closed theory of storm track shifts in dry climates. The relevance of this theory for more realistic moist climates is discussed.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  14. 3-Dimensional simulations of storm dynamics on Saturn

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Sanchez-Lavega, A.

    2000-10-01

    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 of water and ammonia in moist convection is investigated with varying deep concentrations. Results imply that most of the convective activity observed at Saturn may occur at the ammonia cloud deck while the formation of water moist convection may happen only when very strong constraints on the lower troposphere are met. Ammonia storms can ascend to the 300 mb level with vertical velocities around 30 ms-1. The seasonal effect on the thermal profile at the upper troposphere may have important effects on the development of ammonia storms. In the cases where water storms can develop they span many scale heights with peak vertical velocities around 160 ms-1 and cloud particles can be transported up to the 150 mb level. These predicted characteristics are similar to the Great White Spots observed in Saturn which, therefore, could be originated at the water cloud base level. This work has been supported by Gobierno Vasco PI 1997-34. R. Hueso acknowledges a PhD fellowship from Gobierno Vasco.

  15. Temperature measurements of a Martian local dust storm

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph

    1995-01-01

    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 the theories of dust storm development in which regional winds rather than local, dust driven convection initiate the mobilization of dust from the surface. It 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.

  16. Temperature measurements of a Martian local dust storm

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph

    1995-01-01

    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.

  17. Summer Astronomy

    ERIC Educational Resources Information Center

    Riddle, Bob

    2004-01-01

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

  18. Summer Astronomy

    ERIC Educational Resources Information Center

    Riddle, Bob

    2004-01-01

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

  19. Summer Doldrums.

    ERIC Educational Resources Information Center

    Muchnick, Bruce

    2002-01-01

    For camp staff, factors that contribute to the summer doldrums are weather, level of general fatigue, unsatisfied expectations, sensory overload, accumulation of negative "self-talk," and an underlying sense of hurry. Strategies for overcoming summer doldrums involve novelty and stress management, and include promoting health, challenging…

  20. Vorticity imbalance and stability in relation to convection

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Lazar, Dora; Ihasz, Istvan

    2013-04-01

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

  3. Day-time identification of summer hailstorm cells from MSG data

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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%.

  4. Northern hemisphere dust storms on Mars

    NASA Technical Reports Server (NTRS)

    James, P. B.

    1993-01-01

    Dust storms in the northern hemisphere of Mars appear to be less common than the more familiar southern hemisphere storms, and essentially, no activity north of about 30 latittude has been documented. The data are, however, subject to an observational bias because Mars is near aphelion during oppositions, which occur during the most likely seasons for dust activity in the north. The amount of dust activity in the northern hemisphere is clearly very relevant to the role of atmospheric transport in the dust cycle. The classic global storms that occur during spring in the southern hemisphere are observed to transport dust from sources in the southern hemisphere to sinks or temporary depositories in the north. The question of whether atmospheric transport can close the dust cycle, i.e., return the dust to the southern hemisphere sources on some timescale, is clearly relevant to the solution of the puzzle of how the dust storm cycle is modulated, i.e., why storms occur in some years but not in others. There are data that suggest that the spring/early summer season in the northern hemisphere of Mars during the year following the major 1977 storms observed by Viking was very dusty. A number of observations of the vicinity of the receding north polar cap showed clear evidence of substantial dust activity in the sub-Arctic region.

  5. Storms in Space

    NASA Astrophysics Data System (ADS)

    Freeman, John W.

    2012-11-01

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

  6. Large Eddy Simulations of Severe Convection Induced Turbulence

    NASA Technical Reports Server (NTRS)

    Ahmad, Nash'at; Proctor, Fred

    2011-01-01

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

  7. Supergranular Convection

    NASA Astrophysics Data System (ADS)

    Udayashankar, Paniveni

    2015-12-01

    Observation of the Solar photosphere through high resolution instruments have long indicated that the surface of the Sun is not a tranquil, featureless surface but is beset with a granular appearance. These cellular velocity patterns are a visible manifestation of sub- photospheric convection currents which contribute substantially to the outward transport of energy from the deeper layers, thus maintaining the energy balance of the Sun as a whole.Convection is the chief mode of transport in the outer layers of all cool stars such as the Sun (Noyes,1982). Convection zone of thickness 30% of the Solar radius lies in the sub-photospheric layers of the Sun. Here the opacity is so large that heat flux transport is mainly by convection rather than by photon diffusion. Convection is revealed on four scales. On the scale of 1000 km, it is granulation and on the scale of 8-10 arcsec, it is Mesogranulation. The next hierarchial scale of convection , Supergranules are in the range of 30-40 arcsec. The largest reported manifestation of convection in the Sun are ‘Giant Cells’or ‘Giant Granules’, on a typical length scale of about 108 m.'Supergranules' is caused by the turbulence that extends deep into the convection zone. They have a typical lifetime of about 20hr with spicules marking their boundaries. Gas rises in the centre of the supergranules and then spreads out towards the boundary and descends.Broadly speaking supergranules are characterized by the three parameters namely the length L, the lifetime T and the horizontal flow velocity vh . The interrelationships amongst these parameters can shed light on the underlying convective processes and are in agreement with the Kolmogorov theory of turbulence as applied to large scale solar convection (Krishan et al .2002 ; Paniveni et. al. 2004, 2005, 2010).References:1) Noyes, R.W., The Sun, Our Star (Harvard University Press, 1982)2) Krishan, V., Paniveni U., Singh , J., Srikanth R., 2002, MNRAS, 334/1,2303) Paniveni , U., Krishan, V., Singh, J., Srikanth, R., 2004, MNRAS, 347, 1279-12814) Paniveni , U., Krishan, V., Singh, J., Srikanth, R., 2005, Solar Physics, 231, 1-105) Paniveni , U., Krishan, V., Singh, J., Srikanth, R., 2010, MNRAS, 402, Issue 1, 424-428

  8. Interannual variability of planet-encircling dust storms on Mars

    NASA Technical Reports Server (NTRS)

    Zurek, Richard W.; Martin, Leonard J.

    1993-01-01

    A recent review of earth-based telescopic observations of Mars together with Viking orbiter and lander data are employed to estimate the frequency of occurrence of planet-encircling dust storms over the past century and to test whether the period spanned by the Mariner 9 and Viking missions to Mars is representative of the decades prior to 1950. Both spacecraft and earth-based observations suggest that planet-encircling dust storms on Mars occur during a 'dust storm season' in southern spring and summer. Viking data show that planet-encircling dust storms could have occurred in the past on Mars without being detected from earth during years in which Mars was far from earth during the dust storm season. Planet-encircling storms were absent during the dust storm seasons monitored during several favorable oppositions prior to 1956 and after 1986. The change of a planet-encircling dust storm occurring in any arbitrary Mars year is estimated to be approximately one in three, if this occurrence is random from year to year and yet restricted seasonally to southern spring and summer.

  9. Convective initiation in the vicinity of the subtropical Andes

    NASA Astrophysics Data System (ADS)

    Rasmussen, K. L.; Houze, R.

    2014-12-01

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

  10. A methodological critique on using temperature-conditioned resampling for climate projections as in the paper of Gerstengarbe et al. (2013) winter storm- and summer thunderstorm-related loss events in Theoretical and Applied Climatology (TAC)

    NASA Astrophysics Data System (ADS)

    Wechsung, Frank; Wechsung, Maximilian

    2015-08-01

    The STatistical Analogue Resampling Scheme (STARS) statistical approach was recently used to project changes of climate variables in Germany corresponding to a supposed degree of warming. We show by theoretical and empirical analysis that STARS simply transforms interannual gradients between warmer and cooler seasons into climate trends. According to STARS projections, summers in Germany will inevitably become dryer and winters wetter under global warming. Due to the dominance of negative interannual correlations between precipitation and temperature during the year, STARS has a tendency to generate a net annual decrease in precipitation under mean German conditions. Furthermore, according to STARS, the annual level of global radiation would increase in Germany. STARS can be still used, e.g., for generating scenarios in vulnerability and uncertainty studies. However, it is not suitable as a climate downscaling tool to access risks following from changing climate for a finer than general circulation model (GCM) spatial scale.

  11. Subtropical Storm Andrea

    NASA Technical Reports Server (NTRS)

    2007-01-01

    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.

  12. Structure and evolution of flash flood producing storms in a small urban watershed

    NASA Astrophysics Data System (ADS)

    Yang, Long; Smith, James; Baeck, Mary Lynn; Smith, Brianne; Tian, Fuqiang; Niyogi, Dev

    2016-04-01

    The objective of this study is to examine the structure and evolution of storms that produce flash floods in "small" urban watersheds. The study site is Harry's Brook, a 1.1 km2 urban watershed in Princeton, New Jersey. A catalog of 15 storms is developed for Harry's Brook based on paired observations of streamflow and rainfall. Lagrangian analyses of storm properties are based on storm tracking procedures utilizing 3-D radar reflectivity observations from the KDIX (Fort Dix, New Jersey) Weather Surveillance Radar, 1988 Doppler. Analyses focus on the storm elements that were responsible for the peak rainfall rates over the watershed. The 22 July 2006 storm, which produced the record flood peak in the catalog (a unit discharge of 26.8 m3 s-1 km-2) was characterized by thunderstorm cells that produced more than 50 cloud-to-ground lightning strikes and "collapsed" over Harry's Brook. The 3 June 2006 storm, which produced the third largest flood peak (a unit discharge of 11.1 m3 s-1 km-2), was a "low-echo centroid" storm with no lightning. We use cloud-to-ground flash rate, echo top height, maximum reflectivity, and height of maximum reflectivity as key variables for characterizing convective intensity. Storm motion is examined through a time series of storm speed and direction. The 22 July 2006 and 3 June 2006 storms provide end-members of storm properties, centering on "convective intensity," which are associated with flash flooding in small urban watersheds. Extreme 1-15 min rainfall rates are produced by warm season convective systems at both ends of the convective intensity spectrum.

  13. Summer Modification

    NASA Technical Reports Server (NTRS)

    2006-01-01

    5 May 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the outer edge of the south polar residual cap of Mars during southern summer. The variability in brightness across the image would not be as apparent had the data been acquired during late winter or spring, owing to the presence of seasonally deposited, carbon dioxide frost. Over the spring and into early summer, the seasonal carbon dioxide is removed through sublimation, and then the thicker, older accumulations of carbon dioxide -- deposited hundreds or thousands of years ago -- erodes. As this occurs, some surfaces become darker, either because they are roughened by erosion, contain dark material such as mineral dust, or both.

    Location near: 86.9oS, 111.7oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  14. Urban heat islands and summertime convective thunderstorms in Atlanta: three case studies

    NASA Astrophysics Data System (ADS)

    Bornstein, Robert; Lin, Qinglu

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  16. Summer Journal.

    ERIC Educational Resources Information Center

    Evansville-Vanderburgh School Corp., IN.

    This student activity book is intended for junior high or high school students. Originally written to be used in a summer television course, the material can be adapted to a regular class situation. The wide variety of materials are relevant to courses in reading, literature, composition, speech, psychology, and social studies. The book includes…

  17. Summer Programs.

    ERIC Educational Resources Information Center

    Toussaint, Isabella H.

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

  18. Summer Opportunities.

    ERIC Educational Resources Information Center

    Winds of Change, 2002

    2002-01-01

    This directory describes 24 summer internships and cooperative education programs for college students, especially in the science, engineering, and technology fields. A few programs are specifically for American Indians, minority groups, or college-bound high school students. Program entries include a brief description, skills and background…

  19. Summer Opportunities.

    ERIC Educational Resources Information Center

    Winds of Change, 2002

    2002-01-01

    This directory describes 24 summer internships and cooperative education programs for college students, especially in the science, engineering, and technology fields. A few programs are specifically for American Indians, minority groups, or college-bound high school students. Program entries include a brief description, skills and background

  20. Summer Skies

    ERIC Educational Resources Information Center

    Science Scope, 2005

    2005-01-01

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

  1. Summer Camp.

    ERIC Educational Resources Information Center

    Burns, Maxine; And Others

    Government regulation of children's summer camps, particularly involving health and safety standards, is discussed in a series of brief interviews with camp directors and representatives of camp associations. Transcribed from the National Public Radio weekly broadcast, "Options in Education," the program includes a lengthy montage of children's…

  2. Convection towers

    DOEpatents

    Prueitt, Melvin L.

    1994-01-01

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

  3. Convection towers

    DOEpatents

    Prueitt, Melvin L.

    1996-01-01

    Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

  4. Convection towers

    DOEpatents

    Prueitt, M.L.

    1996-01-16

    Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water. 6 figs.

  5. Convection towers

    DOEpatents

    Prueitt, Melvin L.

    1995-01-01

    Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

  6. Modeling Convection

    ERIC Educational Resources Information Center

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

    2004-01-01

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

  7. Modeling Convection

    ERIC Educational Resources Information Center

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

    2004-01-01

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

  8. Modeling of the 22 July 2009 Storm

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Buzulukova, Natalia

    2009-01-01

    The magnetic storm on 22 July 2009 is the greatest storm observed since the summer of 2008 when TWINS began its stereo imaging of the magnetosphere, On 22 July 2009, the Dst dropped to nearly -80 nT at 07:00 and 10:00 UT. During the main phase and at the peak of the storm, TWINS 1 and 2 were near apogee and moving from pre-dawn to post-dawn local time. The energetic neutral atom (ENA) Imagers on the 2 spacecraft captured the storm intensification and the formation of the partial ring current. The development of this storm has been simulated using the Comprehensive Ring Current Model (CRCM) to understand and interpret the observed signatures. The CRCM reproduced the double-dip in the Dst index and the simulated ENA flux intensities agree very well with the TWINS images. However, the peak of ion flux predicted by the model is always eastward of the observed maximum by TWINS. This discrepancy posts a challenge to reexamine the physical models employed in the CRCM.

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  10. Numerical Study of Urbanization Effect on 2012 Heavy Storm Precipitation in Beijing

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    In the past few decades, Great Beijing area has experienced rapid and widespread urbanization, which has significantly modified the land surface physical characteristics and affects urban regional climate.A single layer urban canopy module has been developed based on the Community Land Surface Model Urban Module (CLMU) with improvements: the energy balances on the five surface conditions are considered separately: building roof, sun side and shaded side wall, pervious and impervious land surface. A method to calculate sky view factor is developed based on the physically process while most urban models simply provide an empirical value. This method improves the solar and long wave radiation simulation on each surface; a new scheme for calculating the latent heat flux is applied on both wall and impervious land; the anthropogenic heat is considered in terms of industrial production, domestic wastes, vehicles and air condition. The urban effect on summer convective precipitation under the unstable atmospheric condition over Beijing was investigated by simulating a heavy storm event in July 21st 2012. In this storm, precipitation of averagely 164 mm was brought to Beijing within 6 hours, which is the record of past 60 years in the region. Numerical simulating experiment was set up by coupling Weather Research and Forecast (WRF)/SSiB3 model with the Modified CLMU (MCLMU). Several control cases without MCLMU were set up. The horizontal resolution in the inner domains was set to be 2 km. While all of the control results drastically underestimate the urban precipitation, the result of WRF/SSiB3/MCLMU is much closer to the observation. Sensitive experiments show that 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, which is the key factor for storm while moisture is sufficient.

  11. Summer Appendicitis

    PubMed Central

    Fares, A

    2014-01-01

    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

  12. Severe convective environments in Reanalyses

    NASA Astrophysics Data System (ADS)

    Gutierrez, G.; Kennedy, A. D.

    2014-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Song, J. Aaron; Kaplan, Michael L.

    1991-01-01

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

  14. Convection towers

    DOEpatents

    Prueitt, M.L.

    1994-02-08

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

  15. Effect of storm type on rainwater composition in southeastern North Carolina

    SciTech Connect

    Willey, J.D.; Bennett, R.I.; Williams, J.M. Denne, R.K.; Kornegay, C.R.; Perlotto, M.S.; Moore, B.M.

    1988-01-01

    Rainwater composition in Wilmington, NC, varies as a function of storm origin or type. During 1983-1987, the most acidic rain and highest sulfate and nitrate concentrations occurred in rain from local summer thunderstorms, followed by rain from continental frontal storms, with the least acidic rain coming from coastal storms. Seasonal variation was observed for rainwater pH (although not for sulfate or nitrate concentrations) from continental storms, with the most acidic rain in the summer. Thunderstorm nitrate concentrations were high enough to affect seasonal averages for nitrate concentration because thunderstorms are a warm-season type of rain. Coastal storm rainwater did not show seasonal changes; this type of rainwater is similar in pH, sulfate, and nitrate concentrations to rainwater in remote areas of the world. Sulfate from sea spray was a small percentage of the total sulfate except in coastal storm rainwater. Large annual differences in rainwater composition were observed.

  16. Oxidant Enhancement in Martian Dust Devils and Storms: I. Storm Electric Fields and Electron Dissociative Attachment

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    Laboratory studies, computer 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 or storms, grain stratification (leading to charge separation) gives 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 indicate that this storm electric field on Mars can approach the ambient breakdown field strength of 20 kV/m. Noteable, in terrestrial dust devils, coherent dipolar electric fields have been measured to near 20 kV/m. Given the expected electrostatic fields in Martian dust devils and storms, electrons in the low pressure CO2 gas can be energized via electric fields 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 the ambient electric field, with substantial production of dissociative products when fields approach breakdown levels of 20-30 kV/m. These storm-related chemical products are key ingredients for the generation of oxidants which can ultimately affect the habitability of Mars, as discussed in the following companion presentation.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  18. Wind Shear May Produce Long-Lived Storms and Squall Lines on Titan

    NASA Astrophysics Data System (ADS)

    Rafkin, S.; Barth, E.

    2015-10-01

    The impact of CAPE and wind shear on storms in a Titan-like environment are explored through numerical simulation. Model results indicate that Titan storms should respond to changes in the Richardson Number. Very long-lived storms (>24hours) propagating for 1000 km or more might be possible. Varying amounts of shear in the Titan environment might explain the variety of convective cloud expressions identified in Cassini orbiter and ground-based observations. The resulting distribution and magnitude of precipitation as well as surface winds associated with storms have implications on the formation of fluvial and aeolian features and on the exchange of methane with the surface and lakes.

  19. Effects of Deep Convection on Atmospheric Chemistry

    NASA Technical Reports Server (NTRS)

    Pickering, Kenneth E.

    2007-01-01

    This presentation will trace the important research developments of the last 20+ years in defining the roles of deep convection in tropospheric chemistry. The role of deep convection in vertically redistributing trace gases was first verified through field experiments conducted in 1985. The consequences of deep convection have been noted in many other field programs conducted in subsequent years. Modeling efforts predicted that deep convection occurring over polluted continental regions would cause downstream enhancements in photochemical ozone production in the middle and upper troposphere due to the vertical redistribution of ozone precursors. Particularly large post-convective enhancements of ozone production were estimated for convection occurring over regions of pollution from biomass burning and urban areas. These estimates were verified by measurements taken downstream of biomass burning regions of South America. Models also indicate that convective transport of pristine marine boundary layer air causes decreases in ozone production rates in the upper troposphere and that convective downdrafts bring ozone into the boundary layer where it can be destroyed more rapidly. Additional consequences of deep convection are perturbation of photolysis rates, effective wet scavenging of soluble species, nucleation of new particles in convective outflow, and the potential fix stratosphere-troposphere exchange in thunderstorm anvils. The remainder of the talk will focus on production of NO by lightning, its subsequent transport within convective clouds . and its effects on downwind ozone production. Recent applications of cloud/chemistry model simulations combined with anvil NO and lightning flash observations in estimating NO Introduction per flash will be described. These cloud-resolving case-study simulations of convective transport and lightning NO production in different environments have yielded results which are directly applicable to the design of lightning parameterizations for global chemical transport models. The range of mean values (factor of 3) of NO production per flash (or per meter of lightning channel length) that have been deduced from the model will be shown and compared with values of production in the literature that have been deduced using other methods, Results show that on a per flash basis, IC flashes are nearly as productive of NO as CG flashes. When combined with the global flash rate of 44 flashes per second from NASA's Optical Transient Detector (OTD) measurements, these estimates and the results from other techniques yield global NO production rates of 2-9 TgN/year. Vertical profiles of lightning NOx mass at the end of the 3-D storm simulations have been summarized to yield suggested profiles for use in global models. Simulations of the photochemistry over the 24 hours following a storm have been performed to determine the additional ozone production which can be attributed to lightning NO.

  20. Hazards of geomagnetic storms

    USGS Publications Warehouse

    Herzog, D.C.

    1992-01-01

    Geomagnetic storms are large and sometimes rapid fluctuations in the Earth's magnetic field that are related to disturbances on the Sun's surface. Although it is not widely recognized, these transient magnetic disturbances can be a significant hazard to people and property. Many of us know that the intensity of the auroral lights increases during magnetic storms, but few people realize that these storms can also cause massive power outages, interrupt radio communications and satellite operations, increase corrosion in oil and gas pipelines, and lead to spuriously high rejection rates in the manufacture of sensitive electronic equipment. 

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    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.

  2. Ocean nutrient pathways associated with the passage of a storm

    NASA Astrophysics Data System (ADS)

    Rumyantseva, Anna; Lucas, Natasha; Rippeth, Tom; Martin, Adrian; Painter, Stuart C.; Boyd, Timothy J.; Henson, Stephanie

    2015-08-01

    Storms that affect ocean surface layer dynamics and primary production are a frequent occurrence in the open North Atlantic Ocean. In this study we use an interdisciplinary data set collected in the region to quantify nutrient supply by two pathways associated with a storm event: entrainment of nutrients during a period of high wind forcing and subsequent shear spiking at the pycnocline due to interactions of storm-generated inertial currents with wind. The poststorm increase in surface layer nitrate (by ~20 mmol m-2) was predominantly driven by the first pathway: nutrient intrusion during the storm. Alignment of poststorm inertial currents and surface wind stress caused shear instabilities at the ocean pycnocline, forming the second pathway for nutrient transport into the euphotic zone. During the alignment period, pulses of high-turbulence nitrate flux through the pycnocline (up to 1 mmol m-2 d-1; approximately 25 times higher than the background flux) were detected. However, the impact of the poststorm supply was an order of magnitude lower than during the storm due to the short duration of the pulses. Cumulatively, the storm passage was equivalent to 2.5-5% of the nitrate supplied by winter convection and had a significant effect compared to previously reported (sub)mesoscale dynamics in the region. As storms occur frequently, they can form an important component in local nutrient budgets.

  3. New insights on geomagnetic storms from observations and modeling

    SciTech Connect

    Jordanova, Vania K

    2009-01-01

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

  4. Intensification of Pacific storm track linked to Asian pollution.

    PubMed

    Zhang, Renyi; Li, Guohui; Fan, Jiwen; Wu, Dong L; Molina, Mario J

    2007-03-27

    Indirect radiative forcing of atmospheric aerosols by modification of cloud processes poses the largest uncertainty in climate prediction. We show here a trend of increasing deep convective clouds over the Pacific Ocean in winter from long-term satellite cloud measurements (1984-2005). Simulations with a cloud-resolving weather research and forecast model reveal that the increased deep convective clouds are reproduced when accounting for the aerosol effect from the Asian pollution outflow, which leads to large-scale enhanced convection and precipitation and hence an intensified storm track over the Pacific. We suggest that the wintertime Pacific is highly vulnerable to the aerosol-cloud interaction because of favorable cloud dynamical and microphysical conditions from the coupling between the Pacific storm track and Asian pollution outflow. The intensified Pacific storm track is climatically significant and represents possibly the first detected climate signal of the aerosol-cloud interaction associated with anthropogenic pollution. In addition to radiative forcing on climate, intensification of the Pacific storm track likely impacts the global general circulation due to its fundamental role in meridional heat transport and forcing of stationary waves. PMID:17374719

  5. CONVECTION REACTOR

    DOEpatents

    Hammond, R.P.; King, L.D.P.

    1960-03-22

    An homogeneous nuclear power reactor utilizing convection circulation of the liquid fuel is proposed. The reactor has an internal heat exchanger looated in the same pressure vessel as the critical assembly, thereby eliminating necessity for handling the hot liquid fuel outside the reactor pressure vessel during normal operation. The liquid fuel used in this reactor eliminates the necessity for extensive radiolytic gas rocombination apparatus, and the reactor is resiliently pressurized and, without any movable mechanical apparatus, automatically regulates itself to the condition of criticality during moderate variations in temperature snd pressure and shuts itself down as the pressure exceeds a predetermined safe operating value.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  7. Evaluating Forecasts of Central US Mesoscale Convective Systems in a GCM with Explicit Embedded Convection

    NASA Astrophysics Data System (ADS)

    Kooperman, G. J.; Pritchard, M. S.; Somerville, R. C.; Khairoutdinov, M.

    2011-12-01

    Recent work has demonstrated that the Central US organized nocturnal eastward propagating mode of convection can be captured in a prototype global climate model (GCM) which uses embedded cloud resolving models (CRM) instead of statistical parameterizations to handle sub-grid convection (superparameterization - SPCAM). This is a surprising result since the CRM in SPCAM is idealized in two dimensions with periodic boundary conditions, which restricts fast manifold storm propagation mechanisms to the horizontal scale of a GCM grid box and constrains CRM shear organization to a fixed horizontal plane. Nonetheless, these simulated storms have been qualitatively characterized as having realistic propagation speeds, and have been argued to result from slow manifold pathways linking large-scale dynamics with a prognostic convective lifecycle (CRM memory). However, rigidities in the technique (fixed CRM orientation) and apparent discrepancies in the simulated storm relative flow structure are unresolved issues requiring closer analysis. The Cloud-Associated Parameterizations Testbed (CAPT) approach to evaluating GCM error statistics in forecast mode is applied here to test the sensitivity of this result to CRM orientation and to quantitively compare against observed storm systems that passed over high value ground based sensors at the ARM SGP site. A Newtonian relaxation "nudging" technique has been developed to initialize both resolved scales in SPCAM (GCM and 2D CRM) for forecast simulations, spinning up the CRM by forcing the outer model to follow analyzed observations. Propagating storms are captured in SPCAM with zonal, meridional, and southeast CRM orientations, but comparisons to observations reveal many features of the storm location, thermodynamic structure, and condensate fields to be overly simulated or mispositioned.

  8. Kinetic energy budgets in areas of convection

    NASA Technical Reports Server (NTRS)

    Fuelberg, H. E.

    1979-01-01

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

  9. The 2008 Super Tuesday Tornado Outbreak: Overview of the Tornadoes and their Parent Storms

    NASA Technical Reports Server (NTRS)

    Knupp, Kevin R.; Coleman, Tim; Carey, Larry; Petersen, Walt

    2008-01-01

    The cold-season Tornado outbreak that occurred over the Southeast on 5-6 February 2008 was significant for the following reasons: about 84 tornadoes were documented over a 15 h period between late afternoon on 5 February and early morning on 6 February 2008; a wide variety of parent storms were associated with the tornadoes; a total of five EF-4 tornadoes occurred, with two forming over Alabama during the early morning hours prior to sunrise; there was a significant lull period between the initial convective and the early morning activity over Alabama 10 hours later; and, a wide spectrum of storm types, ranging from isolated supercell storms to QLCS bow echoes, accompanied the tornadoes. The goal of this paper is to provide a general description of the outbreak including the distribution of tornadoes and supercell storms over the region, a detailed map of the tornado tracks, time series of tornadoes and parent storms, and general characteristics of all parent tornado storms. The total number of major storms (duration greater than 3 h, at least three tornadoes produced) was seven. Several noteworthy storms are described: a long track (198 km long) tornado and its parent storm over Arkansas; a prolific supercell storm persisted for 7-8 hours and produced 16 tornadoes from north-central Mississippi to southern KY; and, bow echo storms (QLCS's) were simultaneous over KY and produced 16 tornadoes.

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

    NASA Technical Reports Server (NTRS)

    Rosenfeld, Daniel; Bell, Thomas L.

    2010-01-01

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

  11. The Impact of Hail Size on Simulated Supercell Storms.

    NASA Astrophysics Data System (ADS)

    van den Heever, Susan C.; Cotton, William R.

    2004-07-01

    Variations in storm microstructure due to updraft strength, liquid water content, and the presence of dry layers, wind shear, and cloud nucleating aerosol concentrations are likely to lead to changes in hail sizes within deep convective storms. The focus of this paper is to determine how the overall dynamics and microphysical structure of deep convective storms are affected if hail sizes are somehow altered in a storm environment that is otherwise the same. The sensitivity of simulated supercell storms to hail size distributions is investigated by systematically varying the mean hail diameter from 3 mm to 1 cm using the Regional Atmospheric Modeling System (RAMS) model. Increasing the mean hail diameter results in a hail size distribution in which the number concentration of smaller hailstones is decreased, while that of the larger hailstones is increased. This shift in the hail size distribution as a result of increasing the mean hail diameter leads to an increase in the mean terminal fall speed of the hail species and to reduced melting and evaporation rates. The sensitivity simulations demonstrate that the low-level downdrafts are stronger, the cold pools are deeper and more intense, the left-moving updraft is shorter-lived, the right-moving storm is stronger but not as steady, and the low-level vertical vorticity is greater in the cases with smaller hail stones. The maximum hail mixing ratios are greater in the larger hail simulations, but they are located higher in the storm and farther away from the updraft core in the smaller hail runs. Changes in the hail size distribution also appear to influence the type of supercell that develops.


  12. Convective heater

    DOEpatents

    Thorogood, R.M.

    1983-12-27

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

  13. Convective heater

    DOEpatents

    Thorogood, Robert M.

    1983-01-01

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

  14. Convective heater

    DOEpatents

    Thorogood, Robert M.

    1986-01-01

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

  15. Hurricane and Severe Storm Sentinel (HS3)

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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.

  16. Enhanced seasonality of storm track intensity under global warming

    NASA Astrophysics Data System (ADS)

    Lehmann, Jascha; Coumou, Dim; Frieler, Katja; Eliseev, Alexey; Levermann, Anders

    2013-04-01

    The seasonal cycle of extratropical storms is an important determinant of climatic conditions in regions along mid-latitude storm tracks. Severe storms during winter can cause severe damages over continents, whereas summer storms can actually bring relief to continents subject to prolonged hot and dry periods. It is thus of crucial importance to gain greater insight into the underlying mechanisms driving the seasonal cycle, as well as to assess future scenarios. Here we analyze the seasonality of extratropical storms in 20th and 21st century climates using CMIP5 model runs, based on different greenhouse gas emission scenarios. The synoptic-scale kinetic energy is derived for each individual month using a 2-6 day bandpass filter on daily wind fields. Intra-seasonal variations in storm track intensity are investigated using t-test analysis. The results indicate an enhanced seasonality in storm intensity under all future emission scenarios over both the Atlantic and Pacific region. Moreover, the amplification is significantly stronger for higher emissions. Differences in seasonality trends between the Northern and Southern Hemisphere as well as the underlying mechanisms will be discussed.

  17. Indian Summer

    SciTech Connect

    Galindo, E.

    1997-08-01

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

  18. On extreme geomagnetic storms

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  19. Mobile intercept of storms

    NASA Technical Reports Server (NTRS)

    Arnold, R. T.

    1985-01-01

    The primary goal was to acquire lightning data to serve as ground truth for U2 overflights. Researchers were successful in instrumenting the Univ. of Mississippi/National Severe Storms Lab. (UM/NSSL) mobile laboratory and in coordinating storm intercept through communication to the U2 provided by airplane guidance at NSSL and through direct communication with the U2 pilot from a portable transceiver in the mobile lab. A demonstration showed that a mobile laboratory can be directed within a large geographical area and used to collect ground truth data for comparison with airborne data on a routine basis with proper utilization of forecasts, nowcasts, and communication among all participants. After the U2 flights, researchers turned their attention solely to intercepting severe storms within the area of Oklahoma with good Doppler radar coverage. They incorporated a second vehicle, which followed the mobile lab and from which they released instrumented balloons. This project utilized a standard meteorological rawinsonde and a balloon-borne electric field meter. They were successful in flying, tracking, and receiving data from mobily launched balloons on several days. Researchers believe that they have demonstrated the ability to obtain meteorological and electrical data in severe storms using instrumented balloons. This also includes the capability to launch into the mesocyclone region and for multiple launches in the same storm.

  20. Historically Great Magnetic Storms

    NASA Astrophysics Data System (ADS)

    Cliver, E. W.

    2012-12-01

    What was the largest geomagnetic storm ever recorded? The question is of interest for both theoretical and practical reasons. The available records of magnetic activity indicate that three of the largest storms (in 1859, 1909, and 1921) occurred before the epoch of systematic high-time-resolution indices initiated by Bartels in 1932. Recent efforts to extend such indices back in time enable us to compare the 1909 and 1921 storms with modern giants such as the March 1989 event. Comparisons are made between early reports of auroras at mid-latitudes and magnetic activity. Overhead aurora are associated with particularly strong magnetic disturbances, e.g., the 3000 nT deflection recorded for the 1859 event in Rome.

  1. Storms and Moons

    NASA Technical Reports Server (NTRS)

    2007-01-01

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

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

  2. Heavier summer downpours with climate change revealed by weather forecast resolution model

    NASA Astrophysics Data System (ADS)

    Kendon, Elizabeth J.; Roberts, Nigel M.; Fowler, Hayley J.; Roberts, Malcolm J.; Chan, Steven C.; Senior, Catherine A.

    2014-07-01

    The intensification of precipitation extremes with climate change is of key importance to society as a result of the large impact through flooding. Observations show that heavy rainfall is increasing on daily timescales in many regions, but how changes will manifest themselves on sub-daily timescales remains highly uncertain. Here we perform the first climate change experiments with a very high resolution (1.5 km grid spacing) model more typically used for weather forecasting, in this instance for a region of the UK. The model simulates realistic hourly rainfall characteristics, including extremes, unlike coarser resolution climate models, giving us confidence in its ability to project future changes at this timescale. We find the 1.5 km model shows increases in hourly rainfall intensities in winter, consistent with projections from a coarser 12 km resolution model and previous studies at the daily timescale. However, the 1.5 km model also shows a future intensification of short-duration rain in summer, with significantly more events exceeding the high thresholds indicative of serious flash flooding. We conclude that accurate representation of the local storm dynamics is an essential requirement for predicting changes to convective extremes; when included we find for the model here that summer downpours intensify with warming.

  3. Estimation of cold plasma outflow during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Haaland, S.; Eriksson, A.; André, M.; Maes, L.; Baddeley, L.; Barakat, A.; Chappell, R.; Eccles, V.; Johnsen, C.; Lybekk, B.; Li, K.; Pedersen, A.; Schunk, R.; Welling, D.

    2015-12-01

    Low-energy ions of ionospheric origin constitute a significant contributor to the magnetospheric plasma population. Measuring cold ions is difficult though. Observations have to be done at sufficiently high altitudes and typically in regions of space where spacecraft attain a positive charge due to solar illumination. Cold ions are therefore shielded from the satellite particle detectors. Furthermore, spacecraft can only cover key regions of ion outflow during segments of their orbit, so additional complications arise if continuous longtime observations, such as during a geomagnetic storm, are needed. In this paper we suggest a new approach, based on a combination of synoptic observations and a novel technique to estimate the flux and total outflow during the various phases of geomagnetic storms. Our results indicate large variations in both outflow rates and transport throughout the storm. Prior to the storm main phase, outflow rates are moderate, and the cold ions are mainly emanating from moderately sized polar cap regions. Throughout the main phase of the storm, outflow rates increase and the polar cap source regions expand. Furthermore, faster transport, resulting from enhanced convection, leads to a much larger supply of cold ions to the near-Earth region during geomagnetic storms.

  4. Regional analysis of convective systems during the West African monsoon

    NASA Astrophysics Data System (ADS)

    Guy, Bradley Nicholas

    The West African monsoon (WAM) occurs during the boreal summer and is responsible for a majority of precipitation in the northern portion of West Africa. A distinct shift of precipitation, often driven by large propagating mesoscale convective systems, is indicated from satellite observations. Excepting the coarser satellite observations, sparse data across the continent has prevented understanding of mesoscale variability of these important systems. The interaction between synoptic and mesoscale features appears to be an important part of the WAM system. Without an understanding of the mesoscale properties of precipitating systems, improved understanding of the feedback mechanism between spatial scales cannot be attained. Convective and microphysical characteristics of West African convective systems are explored using various observational data sets. Focus is directed toward meso -alpha and -beta scale convective systems to improve our understanding of characteristics at this spatial scale and contextualize their interaction with the larger-scale. Ground-based radar observations at three distinct geographical locations in West Africa along a common latitudinal band (Niamey, Niger [continental], Kawsara, Senegal [coastal], and Praia, Republic of Cape Verde [maritime]) are analyzed to determine convective system characteristics in each domain during a 29 day period in 2006. Ancillary datasets provided by the African Monsoon Multidisciplinary Analyses (AMMA) and NASA-AMMA (NAMMA) field campaigns are also used to place the radar observations in context. Results show that the total precipitation is dominated by propagating mesoscale convective systems. Convective characteristics vary according to environmental properties, such as vertical shear, CAPE, and the degree of synoptic forcing. Data are bifurcated based on the presence or absence of African easterly waves. In general, African easterly waves appear to enhance mesoscale convective system strength characteristics (e.g. total precipitation and vertical reflectivity profiles) at the inland and maritime sites. The wave regime also resulted in an increased population of the largest observed mesoscale convective systems observed near the coast, which led to an increase in stratiform precipitation. Despite this increase, differentiation of convective strength characteristics was less obvious between wave and no-wave regimes at the coast. Due to the propagating nature of these advecting mesoscale convective systems, interaction with the regional thermodynamic and dynamic environment appears to result in more variability than enhancements due to the wave regime, independent of location. A 13-year (1998-2010) climatology of mesoscale convective characteristics associated with the West African monsoon are also investigated using precipitation radar and passive microwave data from the NASA Tropical Rainfall Measuring Mission satellite. Seven regions defined as continental northeast and northwest, southeast and southwest, coastal, and maritime north and south are compared to analyze zonal and meridional differences. Data are categorized according to identified African easterly wave (AEW) phase and when no wave is present. While some enhancements are observed in association with AEW regimes, regional differences were generally more apparent than wave vs. no-wave differences. Convective intensity metrics confirm that land-based systems exhibit stronger characteristics, such as higher storm top and maximum 30-dBZ heights and significant 85-GHz brightness temperature depressions. Continental systems also contain a lower fraction of points identified as stratiform. Results suggest that precipitation processes also varied depending upon region and AEW regime, with warm-rain processes more apparent over the ocean and the southwest continental region and ice-based microphysics more dominant over land, including mixed-phase processes. AEW regimes did show variability in stratiform fraction and ice and liquid water content, suggesting modulation of mesoscale characteristics possibly through feedback with the synoptic environment. Two mesoscale convective systems (MCSs) observed during the African Monsoon Multidisciplinary Analyses (AMMA) experiment are simulated using the three-dimensional (3D) Goddard Cumulus Ensemble model. One of the MCSs, the 8 September 2006 system, is associated with the passage of an African easterly wave trough while the other, the 14 July 2006 case, is not. Simulations are performed using 1 km horizontal grid spacing, a lower limit on current embedded cloud resolving models within a multi-scale modeling framework. Simulated system structure is compared to radar observations using contoured frequency-by-altitude diagrams (CFADs), calculated ice and water mass, and identified hydrometeor variables. Results indicate general agreement in the temporal distribution of hydrometeors. Vertical distributions show that ice hydrometeors are often underestimated at mid- and upper-levels, partially due to the inability of the model to produce adequate system heights. Abundance of high reflectivity values below and near the melting level in the simulation led to a broadening of the CFAD distributions. Observed vertical reflectivity profiles indicate larger reflectivities aloft compared to simulated values. Despite these differences and biases, the radar-observed differences between the two cases are noticeable in the simulations as well, suggesting that the model is able to capture gross observed differences between the two MCSs.

  5. Multisensor Investigation of Deep Convection

    NASA Astrophysics Data System (ADS)

    Houze, R.; Yuan, J.; Barnes, H. C.; Brodzik, S. R.

    2012-12-01

    The array of sensors for studying cloud systems from space provides the opportunity to globally map the occurrence of various types of deep convective cloud systems more precisely than ever before. The revolutionary TRMM satellite has not only determined rainfall from space but also identified the structures of storms producing the rainfall and how the different types of convective structures relate to features of the global circulation. The multiple sensors of the A-Train constellation have added more capacity to globally map convective cloud system types. By simultaneously using Aqua's MODIS 11-micron brightness temperature sensor to map cloud-top size and coldness, Aqua's AMSR-E passive microwave to detect rainfall, and CloudSat's cloud radar observations to see the internal structure of the nonprecipitating anvil clouds extending laterally from the precipitating cores of mesoscale convective systems (MCSs), we have objectively identified and mapped different types of MCSs. This multisensor analysis has determined the degrees to which MCSs vary according to size, amount of anvil cloud, and whether or not they occur separately or in merged complexes. Using these multisensor-derived quantities, we have established the patterns in which tropical MCSs occur over land, ocean, or the maritime continent. Ongoing work is integrating more sensors and other innovative global datasets into the analysis of A-Train data to further knowledge of MCSs and their variability over the Earth. Global lightning data are being integrated with the A-Train data to better understand convective intensity in different types of MCSs. Environments of the MCSs identified by multisensor A-Train analysis are being further analyzed using AIRS temperature profiles and MODIS and CALIPSO aerosol fields to better document the influence of environmental properties on the different types of mesoscale system. The integration of aerosol loading into the global analysis of the patterns of occurrence of deep convective system identified by multisensor analysis is especially important, as it will be the first truly global assessment of aerosol on the largest atmospheric convective systems. Although we are learning a lot about global patterns of deep MCSs from these multisensor studies, there remains a difficulty. Although the TRMM and A-Train satellite programs are both leading to exciting new information on the global patterns of deep convection and its organization into important mesoscale cloud entities, the knowledge gained from these two satellite programs is difficult to integrate in the quest for a more complete and holistic understanding of deep convection over the Earth. The A-Train data are showing in unprecedented detail aspects of the entire cloud system, and they have the powerful ability to separate the raining cores of the cloud systems from their nonprecipitating anvil clouds. However, the A-Train data lack three-dimensional details on the structure and type of convection. The TRMM radar on the other hand shows the detailed embedded structure of the precipitation cores but lacks information on the nonprecipitating cloud components. Future satellite programs should perhaps focus on how sensors detecting the precipitating components of deep convective cloud systems can be more simultaneously determining information from cloud radars and lidars that best show the nonprecipitating components of the cloud systems.

  6. TWINS Geomagnetic Storm Catalog

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  7. Dust Storms: Why Are Dust Storms a Concern

    MedlinePlus

    ... conditions are extremely dry. Powered by intense ground heating, thunderstorms can produce strong downdrafts. These downdrafts blow up loose sand on the desert floor, creating a dust storm. Dust storms can contain ...

  8. Pilot Convective Weather Decision Making in En Route Airspace

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Blumenfeld, Kenneth A.

    This dissertation investigates the frequency and intensity of severe convective storms, and their associated hazards, in the Twin Cities Metropolitan Area (TCMA), Minnesota. Using public severe weather reports databases and high spatial density rain gauge data, annual frequencies and return-periods are calculated for tornadoes, damaging winds, large hail, and flood-inducing rainfall. The hypothesis that severe thunderstorms and tornadoes are less likely in the central TCMA than in surrounding areas also is examined, and techniques for estimating 100-year rainfall amounts are developed and discussed. This research finds that: (i) storms capable of significant damage somewhere within the TCMA recur annually (sometimes multiple times per year), while storms virtually certain to cause such damage recur every 2-3 years; (ii) though severe weather reports data are not amenable to classical comparative statistical testing, careful treatment of them suggests all types and intensity categories of severe convective weather have been and should continue to be approximately as common in the central TCMA as in surrounding areas; and (iii) applications of Generalized Extreme Value (GEV) statistics and areal analyses of rainfall data lead to significantly larger (25-50%) estimates of 100-year rainfall amounts in the TCMA and parts of Minnesota than those currently published and used for precipitation design. The growth of the TCMA, the popular sentiment that downtown areas somehow deter severe storms and tornadoes, and the prior underestimation of extreme rainfall thresholds for precipitation design, all act to enhance local susceptibility to hazards from severe convective storms.

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

    NASA Technical Reports Server (NTRS)

    Lupo, Kevin

    2012-01-01

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

  11. Storm Warning Service

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A Huntsville meteorologist of Baron Services, Inc. has formed a commercial weather advisory service. Weather information is based on data from Marshall Space Flight Center (MSFC) collected from antennas in Alabama and Tennessee. Bob Baron refines and enhances MSFC's real time display software. Computer data is changed to audio data for radio transmission, received by clients through an antenna and decoded by computer for display. Using his service, clients can monitor the approach of significant storms and schedule operations accordingly. Utilities and emergency management officials are able to plot a storm's path. A recent agreement with two other companies will promote continued development and marketing.

  12. Implications of Global SuperDARN Convection Measurements for the Selection Criteria of Steady Magnetospheric Convection Intervals

    NASA Astrophysics Data System (ADS)

    Pfeifer, J.; McWilliams, K. A.; McPherron, R. L.

    2006-12-01

    Intervals of Steady Magnetospheric Convection (SMC) are loosely defined as times when convection is enhanced and no substorm signatures are observed. Several quantitative definitions have been developed to detect SMC events. These methods make use of AE indices, IMF conditions, in situ magnetotail observations, and the size of the auroral oval. None of these methods, however, relies on directly measured convection, and SMC events are, by definition, a convection phenomena. The SuperDARN radar network is an ideal tool with which to study SMC intervals because it gives a direct measurment of convection on a global scale. In this study we assess previous definitions of SMC using the SuperDARN global convection maps, and we present a modified method of SMC selection, using AE indices. O'Brien et. al. (GRL, 2002) presented a technique using the AE and AL indices to identify SMC intervals. Enhanced convection was quantified by a constant miminum AE cutoff value. Global SuperDARN convection maps for SMC events based on the O'Brien at al. technique revealed a seasonal dependence of the polar cap voltage for these SMC events, with lower voltages measured in the summer months. It is believed to be due to increased ionospheric conductivity in the summer, since AE is derived from ionospheric currents. Thus, equilavent AE values in winter and summer correspond to different levels of convection. Using a method that has a constant minimum AE cutoff therefore results in the selection of intervals that may not satisfy the qualitative criterion of enchanced convection, typical of SMC events. We found an optimal function to quantify enhanced convection, and this function varies throughout the year. By using this function, the seasonal dependance of conductivity on SMC interval selection is minimized. In doing so, the SMC event selection then becomes based primarily on convection.

  13. METEOR - an artificial intelligence system for convective storm forecasting

    SciTech Connect

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

    1987-03-01

    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.

  14. Storm track response to climate change: Insights from simulations using an idealized dry GCM.

    NASA Astrophysics Data System (ADS)

    Mbengue, Cheikh; Schneider, Tapio

    2013-04-01

    The midlatitude storm tracks, where the most intense extratropical cyclones are found, are an important fixture in the general circulation. They are instrumental in balancing the Earth's heat, momentum, and moisture budgets and are responsible for the weather and climatic patterns over large regions of the Earth's surface. As a result, the midlatitude storm tracks are the subject of a considerable amount of scientific research to understand their response to global warming. This has produced the robust result showing that the storm tracks migrate poleward with global warming. However, the dynamical mechanisms responsible for this migration remain unclear. Our work seeks to broaden understanding of the dynamical mechanisms responsible for storm track migration. Competing mechanisms present in the comprehensive climate models often used to study storm track dynamics make it difficult to determine the primary mechanisms responsible for storm track migration. We are thus prompted to study storm track dynamics from a simplified and idealized framework, which enables the decoupling of mean temperature effects from the effects of static stability and of tropical from extratropical effects. Using a statistically zonally symmetric, dry general circulation model (GCM), we conduct a series of numerical simulations to help understand the storm track response to global mean temperatures and to the tropical convective static stability, which we can vary independently. We define storm tracks as regions of zonally and temporally averaged maxima of barotropic eddy kinetic energy (EKE). This storm track definition also allows us to use previously found scalings between the magnitude of bulk measures of mean available potential energy (MAPE) and EKE, to decompose MAPE, and to obtain some mechanistic understanding of the storm track response in our simulations. These simulations provide several insights, which enable us to extend upon existing theories on the mechanisms driving the poleward migration of the storm tracks. We demonstrate a poleward migration of the midlatitude storm tracks in dry atmospheres with fixed pole-equator temperature contrast and increasing radiative equilibrium mean temperature, without changes in convective static stability. We also show scalings between the location of maxima of surface MAPE and of barotropic EKE. In the simulations where we independently vary tropical convective static stability, we find a marked poleward migration of the storm tracks. However, our decomposition shows that meridional temperature gradients, and not static stability, determine the location and the intensity of the storm tracks. This suggests that although the storm tracks are sensitive to tropical convective static stability, it influences them indirectly. Furthermore, our simulations show that the storm tracks generally migrate in tandem with the terminus of the Hadley cell. Therefore, we hypothesize that it is possible that the Hadley cell provides the tropical-extratropical communication necessary to generate the storm track response to tropical convective static stability we observe in the simulations. The results contained herein could be used to supplement ongoing storm track research in moist atmospheres using comparatively more comprehensive GCMs to understand storm track dynamics in earth-like environments.

  15. Inside Martian Dust Storms with the Mars Exploration Rovers' Pancam

    NASA Astrophysics Data System (ADS)

    Lemmon, Mark T.; Landis, G.; Athena Science Team

    2007-10-01

    Near the end of 2006, the Mars Exploration Rovers Spirit and Opportunity entered their second dust storm season on Mars. At the rovers' sites, the season was mild compared to their first Mars year, until nearly LSun 270 (the southern summer solstice). The visible optical depth of the dust was near unity for both rovers, typical of non-storm values from the previous perihelion/summer season. This is elevated from optical depths near 0.2-0.3 (Spirit) or 0.5 (Opportunity) through the aphelion/winter season. Around LSun 265, Opportunity and later Spirit experienced an increase in atmospheric dust to optical depths in excess of 4, in addition to seeing dust lifting and local aeolian transport. The solar powered rovers were entered into a low power mode to attempt to survive the storms. During the waxing of the storms both rovers obtained sky imaging to characterize the dust, which will be presented in this work. The imaging included Sun images to monitor optical depth, horizon images to assess sky color and brightness under changing optical depth conditions, and sky images to characterize scattering of light by the dust. The latter data will be modeled to constrain the size distribution of the dust and its visible/near-infrared absorption spectrum, for comparison to similar pre-storm models.

  16. Electrification in winter storms and the analysis of thunderstorm overflight

    NASA Technical Reports Server (NTRS)

    Brook, Marx

    1991-01-01

    The emergence of 24 hr operational lightning detection networks has led to the finding that positive lightning strokes, although still much fewer in number than the normal negative strokes, are present in summer and winter storms. Recent papers address the importance of understanding the meteorological conditions which lead to a dominance of one polarity of stroke over another; the appearance of positive strokes at the end of a storm appeared to presage the end-of-storm downdraft and subsidence leading to downburst activity. It is beginning to appear that positive strokes may be important meteorological indicators. Significant research accomplishments on the following topics are addressed: (1) a study to verify that the black boxes used in the lightning networks to detect both negative and positive strokes to ground were accurate; (2) the use of slow tails to determine the polarity of distant lightning; (3) lightning initiation in winter vs. summer storms; (4) the upgrade of sensors for the measurement of electric field signals associated with lightning; (5) the analysis of lightning flash records from storms between 40 and 125 km from the sensor; and (6) an interesting aspect of the initiation process which involves the physical processes driving the stepped leader. The focus of current research and future research plans are presented.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Wójcik, Damian; Piotrowski, Zbigniew; Rosa, Bogdan; Ziemiański, Michał

    2014-05-01

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

  19. California's Perfect Storm

    ERIC Educational Resources Information Center

    Bacon, David

    2010-01-01

    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…

  20. Weathering the storm

    SciTech Connect

    Burr, M.T.

    1993-02-01

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

  1. Magnetic Storms in Brazil

    NASA Astrophysics Data System (ADS)

    Pinheiro, K.; Siqueira, F.

    2013-05-01

    Magnetic storms result from atypical processes generated in the Sun, the interaction between the solar wind and the Earth's magnetosphere and the energization of particles in the magnetosphere. As consequence, magnetic storms may cause problems on radio communication, in satellites, GPS imprecision and induce geomagnetic induced currents that my cause saturation and damage of transformers. Magnetic storms are measured in magnetic observatories, where it is possible to observe large variations in the horizontal magnetic field. These variations are most visible in equatorial or low-latitude magnetograms. In this work, we use low latitude dataset from three magnetic observatories in Brazil: Vassouras (Rio de Janeiro) that presents data since 1915, Tatuoca (Pará) since 1957 and data from a new magnetic observatory that was installed in Pantanal (Brazil) on the 22nd October 2012. Vassouras and Pantanal observatories are in the region of the South Atlantic Magnetic Anomaly. External magnetic field interactions in this region are poorly known due to the lack of magnetic data. Tatuoca observatory is located in another important geomagnetic region: the equatorial electrojet. In this work we present the data processing of the recent geomagnetic time series in Pantanal Observatory and its comparison with Vassouras and Tatuoca observatories in Brazil. We analyse the main characteristics of magnetic storms in these observatories, as the sudden commencement and their duration.

  2. Stories from the Storm

    ERIC Educational Resources Information Center

    Smoczynski, Carol

    2007-01-01

    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…

  3. Shallow Water Simulations of the Three Last Saturn's Giant Storms

    NASA Astrophysics Data System (ADS)

    Garcia-Melendo, Enrique; Sanchez-Lavega, Agustin

    2015-11-01

    Shallow Water (SW) simulations are used to present a unified study of the polar (1960), equatorial (1990), and mid-latitude (2010) major storms in Saturn nicknamed as Great White Spots (GWS). The 2010 GWS appeared at +40, moved at -30 m s-1 where the Coriolis force is predominant producing an open anticyclone with a high speed peripheral circulation and a cloud front around the convective source; a long-lived anticyclone; and strong zonal advection on the south part of the storm forming a turbulent region. The 1990 GWS onset took place near the equator, between +12 and +5, on the broad prograde equatorial jet (450 m s-1) where equatorial dynamics dominated producing a storm nucleus, with rapid expansion to the west of a Kelvin-Helmholtz instability on the north side of the perturbation due to advection, and trapped equatorial waves which also expanded the storm to the east around the equator. The 1960 GWS appeared at high latitudes (+56) where Coriolis force is predominant in a region where zonal wind velocity is 0 m s-1. SW simulations predict a strong injection of relative vorticity which may produce large anticyclones on the anticyclonic side of the zonal profile, and a quick turbulent expansion on the background cyclonic regions at mid and high latitudes. In general, simulations indicate that negative relative vorticity injected by the storms also defines the natural interaction with the zonal winds at latitudes where the Coriolis force is dominant dictating its large scale dynamical behavior. Numerical experiments on the 1990 storm indicate that the onset of the storm can only be reproduced if the Voyager era background zonal flow is used, which suggests that it dominated the circulation dynamics at the storm’s outbreak region at that time. They also reproduce its most important morphological features, and show the production of planetary waves and turbulence. We discuss possible mechanism for the observed equatorial jet alterations during the storm expansion.

  4. Cloud-to-ground lightning activity in mesoscale convective complexes

    NASA Technical Reports Server (NTRS)

    Goodman, S. J.; Macgorman, D. R.

    1986-01-01

    An analysis of the evolution of cloud-to-ground lightning discharges attending convective storms in mesoscale convective systems was conducted in the framework of the mesoscale convective complexes (MCCs) life cycle. The lightning discharge data were acquired by a commercially available lightning detection and location system. Peak rates averaged 42/min for the MCCs analyzed; these rates are comparable to the highest observed rates within other mesoscale storm systems and are greater than 20 times the rates previously observed in isolated thunderstorms. Lightning damage occurs with half of the MCCs and is most frequent between the development and the mature phases of the MCC life cycle. The most active period is also characterized by the greatest average number of discrete strokes and largest fraction of multiple-stroke discharges. The total cloud-to-ground lightning activity and maximum flashing rate do not appear to be directly related to either the size of the cloud shield or total duration of the MCC.

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

    SciTech Connect

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

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  7. 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)

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

    2012-04-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Ahn, Yoo-Shin; Brundidge, Kenneth C.

    1987-01-01

    A case study was made of the mesoscale convective complex (MCC) which occurred over southern Oklahoma and northern Texas on 27 May 1981. This storm moved in an eastsoutheasterly direction and during much of its lifetime was observable by radars at Oklahoma City, Ok. and Stephenville, Tx. It was found that the direction of cell (VIP level 3 or more reflectivity) propagation was somewhat erratic but approximately the same as the system (VIP level 1 reflectivity) movement and the ambient wind. New cells developed along and behind the gust front make it appear that once the MCC is initiated, a synergistic relationship exists between the gust front and the MCC. The relationship between rainfall patterns and amounts and the infrared (IR) temperature field in the satellite imagery were examined. The 210 K isotherm of GOES IR imagery was found to encompass the rain area of the storm. The heaviest rainfall was in the vicinity of the VIP level 3 cells and mostly contained within the 205 K isotherm of GOES IR imagery.

  9. TLEs, ITCZ, Storm Tracks and Their Correlation

    NASA Astrophysics Data System (ADS)

    Lee, L.; Chen, A. B.; Tsai, L.; Chou, J.; Chang, S.; Kuo, C.; Su, H.; Hsu, R.; Wu, C.; Lin, P.; Lee, L.

    2008-12-01

    Between July 2004 and February 2008, ISUAL has recorded 6747 elves, 718 sprites, 783 halos, 1081 blue jets, and 17 gigantic jets. We examine the correlation between the distribution of TLEs and the annual Inter- tropical Convergence Zone (ITCZ) distribution by analyzing the outgoing long-wave radiation (OLR) data from NOAA/ESRL Physical Sciences Division. The results indicate that there are two different TLE distribution patterns. For the low latitude region, the movement of TLEs occurrence follows the seasonal migration of the IITCZ. In northern hemisphere summer, the ITCZ is mainly located to the north of the equator and the distribution of TLEs follows. In southern hemisphere summer, part of ITCZ moves to south of the equator and so does the distribution of TLEs. In the middle and high latitude winter regions, the ISUAL recorded TLEs are defined as the winter TLEs, which are generally associated with cold fronts, air masses and mid-latitude cyclones. From the global distribution of winter TLEs, it is shown that they tend to congregate in some specific regions. Namely, in the northern winter , TLEs concentrate over the Japan Sea , north Pacific Ocean , northwest Atlantic Ocean and Mediterranean Sea ; while in the southern winter , TLEs distribute primarily over the south coast of Australia , south Pacific Ocean and east coast of south America. We find the distribution of winter TLEs is well collocated with the storm tracks. The correlation between the winter TLEs and storm tracks is thus analyzed.

  10. Determining the trigger of East Asian dust storms

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-08-01

    In the past 2 decades, there has been a dramatic increase in the occurrence of dust storms over East Asia. The trigger for this increase has been elusive because the ability of gusting wind to whip up a dust storm depends on a large number of factors, ranging from the level of snow and vegetation cover to differences in soil moisture and salt levels. Scientists note that these factors fall into two broad categories: Either the wind has increased its ability to wear away at the earth (increased erosivity), or the soil is more susceptible to the wind's assault (increased erodibility). Using a database of wind speed, weather, and dust storm observations stretching back to 1970, Kurosaki et al. sought to determine whether the East Asian increase was caused by changing erosivity or erodibility. The authors found that the rise in dust storms in desert regions could be attributed largely to an increase in the frequency of strong winds. For crops and grasslands, however, the researchers tied the increase in storms to a change in erodibility, indicating that the soil had somehow changed. They propose that changes in the ground cover provided by dead leaves in the spring could be the driving factor. If so, then observations of plant growth and precipitation during the summer could provide a platform on which to base forecasts of the frequency of dust storms the following year. (Geophysical Research Letters, doi:10.1029/2011GL047494, 2011)

  11. Historic and Future Ice Storms

    NASA Astrophysics Data System (ADS)

    Klima, K.; Morgan, M. G.

    2014-12-01

    Ice storm losses from business interruption as well as transportation and health damages can range into billions of dollars. For instance, the December 2008 New England and Upstate New York ice storm caused four deaths and monetary damages between 2.5 and 3.7 billion, and the 2008 Chinese winter storms resulted in over 130 deaths and over 20 billion in damages. Informal discussions with ice storm experts indicate that due to competing temperature and precipitation effects as well as local topographic effects, it is unclear how exactly climate change will affect ice storms. Here we ask how incident frequencies might change in a future climate at four weather stations prone to ice storms. Using historical atmospheric soundings, we conduct a thought experiment where we perturb the temperatures as might be expected in a future climate. We then discuss changes in monthly frequency of ice storms.

  12. Storm water pollution prevention plans

    SciTech Connect

    Rossmiller, R.L. )

    1993-03-01

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

  13. Storm Tracks Changes and Their Impacts in a Warmer Climate

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Ting, M.; Seager, R.; Huang, H.; Cane, M. A.

    2009-12-01

    Storm tracks play a major role in regulating the precipitation and hydrological cycle at middle latitudes. The changes in the location and intensity of the storm tracks as a result of increased greenhouse gases will have significant impacts on the poleward transport of heat, momentum and moisture. Recent studies have indicated a poleward shift and intensification of the storm tracks and midlatitude precipitation zone in the warming world that will lead to subtropical drying and higher latitude moistening. This study confirms this key feature for not only the annual mean but also different seasons based on the analysis of Geophysical Fluid Dynamics Laboratory (GFDL) model simulations. Further analyses show that the meridional sensible and latent heat fluxes associated with the storm tracks shift poleward and intensify in both boreal summer and winter in the late 21st century. As an ultimate generation mechanism of the midlatitude eddy activities, baroclinic instability has been studied in the future climate as well as in the present climate experiments. It has been found that the trend in Eady growth rate is consistent with the poleward shift and intensification of the storm tracks in the middle latitudes of both hemispheres in both seasons except for the lower troposphere in northern winter. The increased meridional eddy transfer associated with the storm tracks in the lower troposphere in northern winter is more determined by the increased eddy intensity which overwhelms the decreased meridional temperature gradients as indicated by the mixing length theory. This study indicates the relevance of the changing characteristics of baroclinic instability in driving the storm tracks in response to global warming. Furthermore, in order to better understand the physical mechanisms of the changes in storm tracks, the changes in the energy budget of the atmosphere have also been investigated to link the storm tracks with the atmospheric general circulation. By combing the radiative fluxes at the top of the atmosphere and at the surface, including both radiative and nonradiative fluxes, with the surface sensible and latent heat fluxes, a diagnosis of the energy budget in the atmosphere can be performed in the future climate with respect to the present. It has been found that more energy is gained within the tropics and subtropics whereas less at middle and high latitudes in a warmer climate, leading to stronger atmospheric meridional energy transport to the poles. The increased energy transport is primarily at middle latitudes where atmospheric energy transport is carried out in large part by storm tracks. This quantitative analysis not only confirms the strengthening of the storm tracks in the late 21st century but also suggests a sequence of cause and effect of the storm tracks changes in a warmer climate.

  14. Storm-scale ring current morphology inferred from high-resolution empirical magnetic field modeling: storms driven by CMEs, CIRs, and those containing sawtooth and SMC events

    NASA Astrophysics Data System (ADS)

    Stephens, G. K.; Sitnov, M. I.; Ukhorskiy, A. Y.; Ohtani, S.; Vandegriff, J. D.

    2012-12-01

    In spite of several decades of intense investigations, the detailed structure and dynamics of the magnetospheric currents remains unclear especially during disturbed periods associated with magnetic storms and substorms. Until recently, empirical magnetic field models were strongly limited because they were built using predefined, hand-made current structures. New capabilities in the empirical reconstruction of the storm-scale current morphology and its evolution have become possible in the new-generation empirical model, TS07D, where the distribution of storm-scale equatorial currents is determined by regular basis function expansions and is largely dictated by data. We discuss the results of TS07D-based empirical reconstruction of the magnetospheric currents for differing global conditions. Firstly, we examine storms produced by two different drivers, Coronal Mass Ejections (CME) and Corotating Interaction Regions (CIR), and secondly, we examine storms containing two different magnetospheric convection states, those containing quasi-periodic sawtooth events and Steady Magnetospheric Convection (SMC) intervals. A distinctive feature of CME-driven storms is the hook-shaped current developing in the main phase, which combines features of ring and tail currents, while CIR-driven storms are featured by the belt-shaped current and strong reduction of the strength of field-aligned currents. Storms containing sawtooth injections are characterized by the formation of the equatorial storm-time current with an unusually broad radial extension, far beyond geosynchronous orbit across all local times. SMC periods are distinguished by a higher total pressure in the inner magnetosphere extending to larger distances with the appropriate changes in the equatorial currents and their closure paths. New data analysis opportunities offered by the APL-hosted model interface, including run-on-request case studies, the database of pre-processed model coefficients and radiation belt studies are also discussed.

  15. Dynamics Of Saturn'S Mid-scale Storms In The Cassini Era.

    NASA Astrophysics Data System (ADS)

    Del Rio Gaztelurrutia, Teresa; Hueso, R.; Sánchez-Lavega, A.

    2010-10-01

    Convective storms, similar to those in Earth, but of much larger scale, develop often in Saturn's atmosphere. During the Voyagers’ flybys of Saturn in 1981 mid-scale storms, with an horizontal extension of the order of 1000-3000 km were observed to occur mainly in a narrow tropical-latitude band in the Northern hemisphere at latitudes 38-40 deg North. Contrasting with the Voyagers’ era, since the starting of the Cassini mission in 2004, a similar mid-scale convective activity has concentrated in the so-called "storm alley", a narrow band at a symmetric Southern latitude of 38 deg.. In this work, we characterize this storm activity using available visual information provided by Cassini ISS cameras and the continuous survey from the Earth by the International Outer Planets Watch (IOPW) and its online database PVOL (Hueso et al., Planetary and Space Science, 2010). We study the frequency of appearance of storms with sizes above 2000 km, their characteristic size and life-time, as well as their interaction with surrounding dynamical features. In particular we examine the possibility that storms might provide a mechanism of injection of energy into Saturn's jets, the influence of storms in the generation of atmospheric vortices, and the analogies and differences of Voyagers’ and present day jet structure at the relevant latitudes. Acknowledgments: This work has been funded by the Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-464

  16. Extreme Geomagnetic Storms - 1868 - 2010

    NASA Astrophysics Data System (ADS)

    Vennerstrom, S.; Lefevre, L.; Dumbović, M.; Crosby, N.; Malandraki, O.; Patsou, I.; Clette, F.; Veronig, A.; Vršnak, B.; Leer, K.; Moretto, T.

    2016-05-01

    We present the first large statistical study of extreme geomagnetic storms based on historical data from the time period 1868 - 2010. This article is the first of two companion papers. Here we describe how the storms were selected and focus on their near-Earth characteristics. The second article presents our investigation of the corresponding solar events and their characteristics. The storms were selected based on their intensity in the aa index, which constitutes the longest existing continuous series of geomagnetic activity. They are analyzed statistically in the context of more well-known geomagnetic indices, such as the Kp and Dcx/Dst index. This reveals that neither Kp nor Dcx/Dst provide a comprehensive geomagnetic measure of the extreme storms. We rank the storms by including long series of single magnetic observatory data. The top storms on the rank list are the New York Railroad storm occurring in May 1921 and the Quebec storm from March 1989. We identify key characteristics of the storms by combining several different available data sources, lists of storm sudden commencements (SSCs) signifying occurrence of interplanetary shocks, solar wind in-situ measurements, neutron monitor data, and associated identifications of Forbush decreases as well as satellite measurements of energetic proton fluxes in the near-Earth space environment. From this we find, among other results, that the extreme storms are very strongly correlated with the occurrence of interplanetary shocks (91 - 100 %), Forbush decreases (100 %), and energetic solar proton events (70 %). A quantitative comparison of these associations relative to less intense storms is also presented. Most notably, we find that most often the extreme storms are characterized by a complexity that is associated with multiple, often interacting, solar wind disturbances and that they frequently occur when the geomagnetic activity is already elevated. We also investigate the semiannual variation in storm occurrence and confirm previous findings that geomagnetic storms tend to occur less frequently near solstices and that this tendency increases with storm intensity. However, we find that the semiannual variation depends on both the solar wind source and the storm level. Storms associated with weak SSC do not show any semiannual variation, in contrast to weak storms without SSC.

  17. Severe storm electricity

    NASA Technical Reports Server (NTRS)

    Rust, W. D.; Macgorman, D. R.

    1985-01-01

    During FY-85, Researchers conducted a field program and analyzed data. The field program incorporated coordinated measurements made with a NASA U2. Results include the following: (1) ground truth measurements of lightning for comparison with those obtained by the U2; (2) analysis of dual-Doppler radar and dual-VHF lightning mapping data from a supercell storm; (3) analysis of synoptic conditions during three simultaneous storm systems on 13 May 1983 when unusually large numbers of positive cloud-to-ground (+CG) flashes occurred; (4) analysis of extremely low frequency (ELF) wave forms; and (5) an assessment of a cloud -ground strike location system using a combination of mobile laboratory and fixed-base TV video data.

  18. Dust Storm, Aral Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    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

  19. Severe storm electricity

    NASA Technical Reports Server (NTRS)

    Arnold, R. T.; Rust, W. D.

    1984-01-01

    Successful ground truth support of U-2 overflights was been accomplished. Data have been reduced for 4 June 1984 and some of the results have been integrated into some of MSFC's efforts. Staccato lightning (multiply branched, single stroke flash with no continuing current) is prevalent within the rainfree region around the main storm updraft and this is believed to be important, i.e., staccato flashes might be an important indicator of severe storm electrification. Results from data analysis from two stations appear to indicate that charge center heights can be estimated from a combination of intercept data with data from the fixed laboratory at NSSL. An excellent data base has been provided for determining the sight errors and efficiency of NSSL's LLP system. Cloud structures, observable in a low radar reflectivity region and on a scale smaller than is currently resolved by radar, which appear to be related to electrical activity are studied.

  20. Morphology of Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Vestine, E. H.

    1961-01-01

    This publication is a product of the continuing study of the properties of charged particles and fields in space being conducted by The RAND Corporation under contract No. NAS5-276 for the National Aeronautics and Space Administration. Magnetic storms, revealed by world-wide changes in the intensity of the earth's magnetic field, and emphasized by disturbances in electromagnetic communication channels, form detectable patterns on the surface of the earth and above it. The author draws together data from various times, places, and altitudes and, coupling these with what is known or inferred about the aurora, the ionosphere, and the relationship between them and the earth's radiation belts, creates a picture of what is believed to occur during a magnetic storm.

  1. Energy and Mass Transport of Magnetospheric Plasmas during the November 2003 Magnetic Storm

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Chging; Moore, Thomas

    2008-01-01

    Intensive energy and mass transport from the solar wind across the magnetosphere boundary is a trigger of magnetic storms. The storm on 20-21 November 2003 was elicited by a high-speed solar wind and strong southward component of interplanetary magnetic field. This storm attained a minimum Dst of -422 nT. During the storm, some of the solar wind particles enter the magnetosphere and eventually become part of the ring current. At the same time, the fierce solar wind powers strong outflow of H+ and O+ from the ionosphere, as well as from the plasmasphere. We examine the contribution of plasmas from the solar wind, ionosphere and plasmasphere to the storm-time ring current. Our simulation shows, for this particular storm, ionospheric O+ and solar wind ions are the major sources of the ring current particles. The polar wind and plasmaspheric H+ have only minor impacts. In the storm main phase, the strong penetration of solar wind electric field pushes ions from the geosynchronous orbit to L shells of 2 and below. Ring current is greatly intensified during the earthward transport and produces a large magnetic depression in the surface field. When the convection subsides, the deep penetrating ions experience strong charge exchange loss, causing rapid decay of the ring current and fast initial storm recovery. Our simulation reproduces very well the storm development indicated by the Dst index.

  2. Development in the STORM

    PubMed Central

    Kamiyama, Daichi; Huang, Bo

    2012-01-01

    The recent invention of super-resolution microscopy has brought up much excitement in the biological research community. Here, we will focus on Stochastic Optical Reconstruction Microscopy/Photoactivated Localization Microscopy (STORM/PALM) to discuss the challenges in applying super-resolution microscopy to the study of developmental biology, including tissue imaging, sample preparation artifacts, and image interpretation. We will also summarize new opportunities that super-resolution microscopy could bring to the field of developmental biology. PMID:23237944

  3. Ice Storm Supercomputer

    ScienceCinema

    None

    2013-05-28

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

  4. The relationship of storm severity to directionally resolved radio emissions

    NASA Technical Reports Server (NTRS)

    Johnson, R. L.

    1986-01-01

    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.

  5. Wind Shear May Produce Long-Lived Storms and Squall Lines on Titan

    NASA Astrophysics Data System (ADS)

    Rafkin, Scot C. R.; Barth, Erika

    2015-11-01

    The impact of CAPE and wind shear on storms in a Titan-like environment are explored through numerical simulation. Numerical modeling indicates that both large-scale shear and CAPE environment control the dynamics of the clouds. This response to the large-scale environment is analogous to the behavior of deep convective clouds on Earth. The balance between shear and CAPE, as expressed through the bulk Richardson Number (NR), is a good indicator of the response of a storm to its environment. Large NR results in short-lived single cell storms (Figure 1). As shear increases for a given CAPE, and NR decreases, the storms transition to a multicellular regime. Multicellular storms are longer-lived and are characterized by a downdraft generated cold pool that interacts with the background shear vorticity to initiate cells along the leading edge of the storm gust front (Figure 2). Very long-lived storms (>24 hours) propagating for 1000 km or more might be possible. The most intense multicellular systems simulated in this study behave similar to terrestrial squall lines, and very long-lived storms (>24 hours) propagating for 1000 km or more might be possible. Cloud outbursts and linear cloud features observed from ground and Cassini may be the result of these organized storm systems. Varying amounts of shear in the Titan environment might explain the variety of convective cloud expressions identified in Cassini orbiter and ground-based observations. The resulting distribution and magnitude of precipitation as well as surface winds associated with storms have implications on the formation of fluvial and aeolian features, including dunes, and on the exchange of methane with the surface and lakes.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    PubMed

    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

    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

  8. Oxidant Enhancement in Martian Dust Devils and Storms: Storm Electric Fields and Electron Dissociative Attachment

    NASA Astrophysics Data System (ADS)

    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

    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 ~25 kV/m. In terrestrial dust phenomena, potentials ranging from ~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 ~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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  10. Defining Coastal Storm and Quantifying Storms Applying Coastal Storm Impulse Parameter

    NASA Astrophysics Data System (ADS)

    Mahmoudpour, Nader

    2014-05-01

    What defines a storm condition and what would initiate a "storm" has not been uniquely defined among scientists and engineers. Parameters that have been used to define a storm condition can be mentioned as wind speed, beach erosion and storm hydrodynamics parameters such as wave height and water levels. Some of the parameters are storm consequential such as beach erosion and some are not directly related to the storm hydrodynamics such as wind speed. For the purpose of the presentation, the different storm conditions based on wave height, water levels, wind speed and beach erosion will be discussed and assessed. However, it sounds more scientifically to have the storm definition based on the hydrodynamic parameters such as wave height, water level and storm duration. Once the storm condition is defined and storm has initiated, the severity of the storm would be a question to forecast and evaluate the hazard and analyze the risk in order to determine the appropriate responses. The correlation of storm damages to the meteorological and hydrodynamics parameters can be defined as a storm scale, storm index or storm parameter and it is needed to simplify the complexity of variation involved developing the scale for risk analysis and response management. A newly introduced Coastal Storm Impulse (COSI) parameter quantifies storms into one number for a specific location and storm event. The COSI parameter is based on the conservation of linear, horizontal momentum to combine storm surge, wave dynamics, and currents over the storm duration. The COSI parameter applies the principle of conservation of momentum to physically combine the hydrodynamic variables per unit width of shoreline. This total momentum is then integrated over the duration of the storm to determine the storm's impulse to the coast. The COSI parameter employs the mean, time-averaged nonlinear (Fourier) wave momentum flux, over the wave period added to the horizontal storm surge momentum above the Mean High Water (MHW) integrated over the storm duration. The COSI parameter methodology has been applied to a 10-year data set from 1994 to 2003 at US Army Corps of Engineers, Field Research Facility (FRF) located on the Atlantic Ocean in Duck, North Carolina. The storm duration was taken as the length of time (hours) that the spectral significant wave heights were equal or greater than 1.6 meters for at least a 12 hour, continuous period. Wave heights were measured in 8 meters water depth and water levels measured at the NOAA/NOS tide gauge at the end of the FRF pier. The 10-year data set were analyzed applying the aforementioned storm criteria and produced 148 coastal events including Hurricanes and Northeasters. The results of this analysis and application of the COSI parameter to determine "Extra Ordinary" storms in Federal Projects for the Gulf of Mexico, 2012 hurricane season will be discussed at the time of presentation.

  11. Spatiotemporal variability of summer precipitation in southeastern Arizona

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  12. Observations of contemporaneous lightning storms in Saturn's atmosphere

    NASA Astrophysics Data System (ADS)

    Fischer, G.; Dyudina, U. A.; Delcroix, M.; Pagaran, J. A.

    2013-09-01

    In contrast to Jupiter, where multiple lightning storms take place at various latitudes at the same time [1], the situation at Saturn seems more restricted. First, so far Saturnian lightning storms have only been observed at the equator, and at the planetocentric latitudes of 35° and 50° in both hemispheres. Second, the typical situation at Saturn is that there is only one months-long lightning storm at one time since their occurrence probability is lower than at Jupiter. However, in this presentation we will show the details of three situations where multiple storms were also present at Saturn. The most recent one was in early 2011, when a 2000-km sized storm at 50° north was initially overlooked due to the spectacular presence of the 2010/2011 Great White Spot around 35° north [2]. The second case was in spring 2008, when a single lightning storm at 35° south split into two distinct thunderstorm cells that resided at the same latitude but separated by about 30° in longitude. The third case can be inferred from the irregular occurrence of SEDs (Saturn Electrostatic Discharges, radio emissions from Saturn lightning) during the Voyager 2 encounter in 1981 [3]. The almost permanent presence of SEDs during the whole flyby suggests the contemporaneous existence of multiple storms, most likely located at 35° north and/or the equator. In general, the giant Great White Spots raging at Saturn usually only once per Saturn year [4], must consist of multiple thunderstorm cells at adjacent latitudes. It is likely that the presence of a strong thunderstorm cell can trigger the development of others around the same latitude on Saturn. Similar to observations at Earth, the triggering mechanism could be the propagation of convectively generated atmospheric gravity waves [5].

  13. Oxidant Enhancement in the Martian dust devils and Storms: I. Storm electric fields and electron dissociative attachment

    NASA Astrophysics Data System (ADS)

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

    2004-11-01

    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 or dust storms, grain stratification (leading to charge separation) gives 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 indicate that this storm electric field on Mars can approach the ambient breakdown field strength of 20 kV/m. In terrestrial dust devils, coherent dipolar electric fields have been measured near 20 kV/m. Given the expected electrostatic fields in Martian dust devils and storms, electrons in the low pressure CO2 gas can be energized via the fields 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 the ambient electric field, with substantial production of dissociative products when fields approach breakdown levels 20-30 kV/m. These storm-related chemical products are key ingredients for the generation of oxidants which can ultimately affect the habitability of Mars, as discussed in the following presentation.

  14. The Summer Monsoon of 1987.

    NASA Astrophysics Data System (ADS)

    Krishnamurti, T. N.; Bedi, H. S.; Subramaniam, M.

    1989-04-01

    In this paper we have examined the evolution of a number of parameters we believe were important for our understanding of the drought over India during the summer of 1987. The list of parameters includes monthly means or anomalies of the following fields: sea surface temperatures, divergent circulations, outgoing longwave radiation, streamfunction of the lower and upper troposphere, and monthly precipitation (expressed as a percentage departure from a long-term mean). The El Niño related warm sea surface temperature anomaly and a weaker warm sea surface temperature anomaly over the equatorial Indian Ocean provide sustained convection, as reflected by the negative values of the outgoing longwave radiation. With the seasonal heating, a pronounced planetary-scale divergent circulation evolved with a center along the western Pacific Ocean. The monsoonal divergent circulation merged with that related to the El Niño, maintaining most of the heavy rainfall activity between the equatorial Pacific Ocean and east Asia. Persistent convective activity continued south of India during the entire monsoon season. Strong Hadley type overturnings with rising motions over these warm SST anomaly regions and descent roughly near 20° to 25°S was evident as early as April 1987. The subtropical high pressure areas near 20° to 25°S showed stronger than normal circulations. This was revealed by the presence of a counterclockwise streamfunction anomaly at 850 mb during April 1987. With the seasonal heating, this anomaly moved northwards and was located over the Arabian Sea and India. This countermonsoon circulation anomaly at the low levels was associated with a weaker than normal Somali jet and Arabian Sea circulation throughout this summer. The monsoon remained active along northeast India, Bangladesh, northern lndochina, and central China during the summer monsoon season. This was related to the eastward shift of the divergent circulation. An eastward shift of the upper tropospheric anticyclone bell near 25° to 30°N resulted in the continued presence of a westerly wind anomaly north of India. The westerly winds brought in very dry air over the tropical upper troposphere. The dry air penetrated eastwards to central Uttar Pradesh and this seemed to have a major role in inhibiting organized deep convection over most of central, northern and western parts of the Indian subcontinent. The westward extension of the planetary-scale divergent circulation over North and South Africa and the continued drought over the regions are also briefly addressed.

  15. Evaluating and Understanding Parameterized Convective Processes and their Role in the Development of Mesoscale Precipitation Systems

    NASA Technical Reports Server (NTRS)

    Fritsch, J. Michael; Kain, John S.

    1997-01-01

    Research efforts during the second year have centered on improving the manner in which convective stabilization is achieved in the Penn State/NCAR mesoscale model MM5. Ways of improving this stabilization have been investigated by (1) refining the partitioning between the Kain-Fritsch convective parameterization scheme and the grid scale by introducing a form of moist convective adjustment; (2) using radar data to define locations of subgrid-scale convection during a dynamic initialization period; and (3) parameterizing deep-convective feedbacks as subgrid-scale sources and sinks of mass. These investigations were conducted by simulating a long-lived convectively-generated mesoscale vortex that occurred during 14-18 Jul. 1982 and the 10-11 Jun. 1985 squall line that occurred over the Kansas-Oklahoma region during the PRE-STORM experiment. The long-lived vortex tracked across the central Plains states and was responsible for multiple convective outbreaks during its lifetime.

  16. TRMM precipitation analysis of extreme storms in South America: Bias and climatological contribution

    NASA Astrophysics Data System (ADS)

    Rasmussen, K. L.; Houze, R.; Zuluaga, M. D.; Choi, S. L.; Chaplin, M.

    2013-12-01

    The TRMM (Tropical Rainfall Measuring Mission) satellite was designed both to measure spatial and temporal variation of tropical rainfall around the globe and to understand the factors controlling the precipitation. TRMM observations have led to the realization that storms just east of the Andes in southeastern South America are among the most intense deep convection in the world. For a complete perspective of the impact of intense precipitation systems on the hydrologic cycle in South America, it is necessary to assess the contribution from various forms of extreme storms to the climatological rainfall. However, recent studies have suggested that the TRMM Precipitation Radar (PR) algorithm significantly underestimates surface rainfall in deep convection over land. Prior to investigating the climatological behavior, this research first investigates the range of the rain bias in storms containing four different types of extreme radar echoes: deep convective cores, deep and wide convective cores, wide convective cores, and broad stratiform regions over South America. The TRMM PR algorithm exhibits bias in all four extreme echo types considered here when the algorithm rates are compared to a range of conventional Z-R relations. Storms with deep convective cores, defined as high reflectivity echo volumes that extend above 10 km in altitude, show the greatest underestimation, and the bias is unrelated to their echo top height. The bias in wide convective cores, defined as high reflectivity echo volumes that extend horizontally over 1,000 km2, relates to the echo top, indicating that storms with significant mixed phase and ice hydrometeors are similarly affected by assumptions in the TRMM PR algorithm. The subtropical region tends to have more intense precipitating systems than the tropics, but the relationship between the TRMM PR rain bias and storm type is the same regardless of the climatological regime. The most extreme storms are typically not collocated with regions of high climatological precipitation. A quantitative approach that accounts for the previously described bias using TRMM PR data is employed to investigate the role of the most extreme precipitating systems on the hydrological cycle in South America. These data are first used to investigate the relative contribution of precipitation from the TRMM-identified echo cores to each separate storm in which the convective cores are embedded. The second part of the study assesses how much of the climatological rainfall in South America is accounted for by storms containing deep convective, wide convective, and broad stratiform echo components. Systems containing these echoes produce very different hydrologic responses. From a hydrologic and climatological viewpoint, this empirical knowledge is critical, as the type of runoff and flooding that may occur depends on the specific character of the convective storm and has broad implications for the hydrological cycle in this region.

  17. Deep convection in the Sahel : a focus on gust fronts

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    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.

  19. Energy analysis of convectively induced wind perturbations

    NASA Technical Reports Server (NTRS)

    Fuelberg, Henry E.; Buechler, Dennis E.

    1989-01-01

    Budgets of divergent and rotational components of kinetic energy (KD and KR) are examined for four upper level wind speed maxima that develop during the fourth Atmospheric Variability Experiment (AVE IV) and the first AVE-Severe Environmental Storms and Mesoscale Experiment (AVE-SESAME I). A similar budget analysis is performed for a low-level jet stream during AVE-SESAME I. The energetics of the four upper level speed maxima is found to have several similarities. The dominant source of KD is cross-contour flow by the divergent wind, and KD provides a major source of KR via a conversion process. Conversion from available potential energy provides an additional source of KR in three of the cases. Horizontal maps reveal that the conversions involving KD are maximized in regions poleward of the convection. Low-level jet development during AVE-SESAME I appears to be assisted by convective activity to the west.

  20. The News, Summer 1999-Summer 2000.

    ERIC Educational Resources Information Center

    Robertson, Trische, Ed.

    2000-01-01

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

  1. Polar Cap Potential Saturation and Ionospheric Convection Patterns during Superstorms

    NASA Astrophysics Data System (ADS)

    Du, A.; Sun, W.; Tsurutani, B.

    2012-12-01

    Five super intense magnetic storms (with minimum Dst < -200 nT) were examined to investigate the relationship between polar cap potential (PCP) saturation and ionospheric convection patterns. A quantitative method was used to determine whether or not PCP was saturated by applying both linear and nonlinear (exponential) fits for each event. The results showed that PCP saturation occurred for two of five. The two events with saturation had distorted ionospheric convection patterns (D-CONV) with asymmetric vortices, while for the other three events without PCP saturation had well-known standard convection (S-CONV) with quasi-symmetric twin vortices. The authors conclude that sporadic midnight sector substorm electric fields may contribute to the asymmetric convection patterns and PCP saturation, in agreement with previous speculations. Further analyses are needed to confirm this hypothesis.t;

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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

  3. Empirical STORM-E model: I. Theoretical and observational basis

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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 μm channel limb radiance measurements. The storm-time response of the NO+(v) 4.3 μm 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 μm 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 μm limb emission measurements is given. Finally, an assessment of key uncertainties in retrieving NO+(v) VER is presented.

  4. Hubble Tracks Jupiter Storms

    NASA Technical Reports Server (NTRS)

    1995-01-01

    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/

  5. Storm Tracks Across Eastern Canada

    NASA Astrophysics Data System (ADS)

    Plante, Mathieu; Son, Seok-Woo; Gyakum, John; Kevin, Grise

    2013-04-01

    The global storm tracks patterns across the Northern Hemisphere are well documented, but their regional impact on populations has yet to be characterized, as very few studies took a local perspective on storm tracks. In this study, a Lagrangian tracking algorithm is applied to the 850 hPa relative vorticity field to characterize extratropical storm tracks that pass through major cities in Canada. Storm tracks are first classified in reference to the metropolitan cities that they impact, such as Toronto, Montreal, Halifax and St-John's. They are then subjected to several analyses, including but not limited to the identification of main development regions, typical tracks, mean growth rate, intensity and typical regions of decay. We found that the preferential development regions are the lee of the Rockies, the Great Lakes and the Western Atlantic. The collection of storm tracks across each city is composed of storms developing not from a single development region, but from several. Results show that the storm track variability at a city is dominated by the storm track variability of its predominant development region. Among others, we found that the ensembles of storms crossing East coast cities (Halifax, St-John's) are dominated by Atlantic storms that are most frequent during the winter. Storms passing through Montreal and Toronto travel primarily from the Great Lakes and the mid-latitude Rockies. In eastern Canada, storms from the southernmost part of the Rockies are much less frequent, but this development region is the main source of extreme storms, and is thus important in terms of impacts on metropolitan areas. The relationship between storm tracks and modes of atmospheric variability are also examined with an emphasis on the El Nino Southern Oscillation (ENSO) and Northern Annular Mode (NAM). We found that teleconnection shifts storm tracks differently in different development regions. The anomalous storm track densities are presented, as well as their direct impact on specific metropolitan areas. Results show that the combination of these shifts impact cities differently according to their geographic location.

  6. Storm impact for barrier islands

    USGS Publications Warehouse

    Sallenger,, Asbury H., Jr.

    2000-01-01

    A new scale is proposed that categorizes impacts to natural barrier islands resulting from tropical and extra-tropical storms. The proposed scale is fundamentally different than existing storm-related scales in that the coupling between forcing processes and the geometry of the coast is explicitly included. Four regimes, representing different levels of impact, are defined. Within each regime, patterns and relative magnitudes of net erosion and accretion are argued to be unique. The borders between regimes represent thresholds defining where processes and magnitudes of impacts change dramatically. Impact level 1 is the 'swash' regime describing a storm where runup is confined to the foreshore. The foreshore typically erodes during the storm and recovers following the storm; hence, there is no net change. Impact level 2 is the 'collision' regime describing a storm where the wave runup exceeds the threshold of the base of the foredune ridge. Swash impacts the dune forcing net erosion. Impact level 3 is the 'overwash' regime describing a storm where wave runup overtops the berm or, if present, the foredune ridge. The associated net landward sand transport contributes to net migration of the barrier landward. Impact level 4 is the 'inundation' regime describing a storm where the storm surge is sufficient to completely and continuously submerge the barrier island. Sand undergoes net landward transport over the barrier island; limited evidence suggests the quantities and distance of transport are much greater than what occurs during the 'overwash' regime.

  7. Projections of Increased Intensity of Summer Rainfall over the UK from Very High Resolution Regional Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Fowler, H. J.; Kendon, E. J.; Chan, S. C.; Roberts, N. M.; Roberts, M.; Senior, C. A.

    2014-12-01

    We have performed the first climate change experiments with a very high resolution (1.5 km grid spacing) regional climate model over a region of the UK and compared these to results for a coarser resolution climate model (12 km). This model is typically used for weather forecasting in the UK. Although observations show increases in heavy rainfall at daily timescales in many regions, how changes will manifest themselves on sub-daily timescales remains highly uncertain. A reanalysis-driven simulation shows realistic hourly rainfall characteristics, including extremes, unlike results for coarser resolution climate models. This gives us confidence in the very high resolution model's ability to project future changes at sub-daily scales. The 1.5 km model shows increases in hourly rainfall intensities in winter, consistent with projections from the coarser 12 km resolution model and from previous studies at the daily timescale. However, the 1.5 km model also shows future intensification of short-duration heavy rainfall in summer with significantly more events exceeding the high thresholds set by UK flood forecasters as indicative of serious flash flooding. We conclude that accurate representation of the local storm dynamics is an essential requirement for predicting changes to convective extremes; when included we find for the model here that summer downpours intensify with warming. We further explore some of the mechanisms causing the changes, including the relationships to temperature and humidity through mechanisms such as the Clausius-cCapeyron relationship, and larger scale circulation changes.

  8. The geomagnetic storm time response of GPS total electron content in the North American sector

    NASA Astrophysics Data System (ADS)

    Thomas, E. G.; Baker, J. B. H.; Ruohoniemi, J. M.; Coster, A. J.; Zhang, S.-R.

    2016-02-01

    Over the last two decades, maps of GPS total electron content (TEC) have improved our understanding of the large perturbations in ionospheric electron density which occur during geomagnetic storms. However, previous regional and global studies of ionospheric storms have performed only a limited separation of storm time, local time, longitudinal, and seasonal effects. Using 13 years of GPS TEC data, we present a complete statistical characterization of the ionospheric response to geomagnetic storms for midlatitudes in the North American sector where dense ground receiver coverage is available. The rapid onset of a positive phase is observed across much of the dayside and evening ionosphere followed by a longer-lasting negative phase across all latitudes and local times. Our results show clear seasonal variations in the storm time TEC, such that summer events tend to be dominated by the negative storm response while winter events exhibit a stronger initial positive phase with minimal negative storm effects. We find no discernable difference between spring and fall equinox events with both being equivalent to the average storm time response across all seasons. We also identify a prominent magnetic declination effect such that stronger dayside positive storm effects are observed in regions of negative declination (i.e., eastern North America). On the nightside, asymmetries in the TEC response are observed near the auroral oval and midlatitude trough which may be attributed to thermospheric zonal winds pushing plasma upward/downward along field lines of opposite declination.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  10. Solar radio continuum storms

    NASA Technical Reports Server (NTRS)

    Sakurai, K.

    1976-01-01

    The paper reviews the current status of research on solar radio continuum emissions from metric to hectometric wave frequencies, emphasizing the role of energetic electrons in the 10-100 keV range in these emissions. It is seen that keV-energy electrons generated in active sunspot groups must be the sources of radio continuum storm emissions for wide frequency bands. These electrons excite plasma oscillations in the medium, which in turn are converted to electromagnetic radiation. The radio noise continuum sources are usually associated with type III burst activity observed above these sources. Although the mechanism for the release of the energetic electrons is not known, it seems they are ejected from storm source regions in association with rapid variation of associated sunspot magnetic fields due to their growth into complex types. To explain some of the observed characteristics, the importance of two-stream instability and the scattering of ambient plasma ions on energetic electron streams is pointed out.

  11. Severe storm electricity

    NASA Technical Reports Server (NTRS)

    Rust, W. D.; Macgorman, D. R.; Taylor, W.; Arnold, R. T.

    1984-01-01

    Severe storms and lightning were measured with a NASA U2 and ground based facilities, both fixed base and mobile. Aspects of this program are reported. The following results are presented: (1) ground truth measurements of lightning for comparison with those obtained by the U2. These measurements include flash type identification, electric field changes, optical waveforms, and ground strike location; (2) simultaneous extremely low frequency (ELF) waveforms for cloud to ground (CG) flashes; (3) the CG strike location system (LLP) using a combination of mobile laboratory and television video data are assessed; (4) continued development of analog-to-digital conversion techniques for processing lightning data from the U2, mobile laboratory, and NSSL sensors; (5) completion of an all azimuth TV system for CG ground truth; (6) a preliminary analysis of both IC and CG lightning in a mesocyclone; and (7) the finding of a bimodal peak in altitude lightning activity in some storms in the Great Plains and on the east coast. In the forms on the Great Plains, there was a distinct class of flash what forms the upper mode of the distribution. These flashes are smaller horizontal extent, but occur more frequently than flashes in the lower mode of the distribution.

  12. A study of severe storm electricity via storm intercept

    NASA Technical Reports Server (NTRS)

    Arnold, Roy T.; Horsburgh, Steven D.; Rust, W. David; Burgess, Don

    1985-01-01

    Storm electricity data, radar data, and visual observations were used both to present a case study for a supercell thunderstorm that occurred in the Texas Panhandle on 19 June 1980 and to search for insight into how lightning to ground might be related to storm dynamics in the updraft/downdraft couplet in supercell storms. It was observed that two-thirds of the lightning ground-strike points in the developing and maturing stages of a supercell thunderstorm occurred within the region surrounding the wall cloud (a cloud feature often characteristic of a supercell updraft) and on the southern flank of the precipitation. Electrical activity in the 19 June 1980 storm was atypical in that it was a right-mover. Lightning to ground reached a peak rate of 18/min and intracloud flashes were as frequent as 176/min in the final stages of the storm's life.

  13. Influence of global dust storms on the mesosphere and lower thermosphere of Mars

    NASA Astrophysics Data System (ADS)

    Medvedev, A. S.; Yigit, E.; Kuroda, T.; Hartogh, P.

    2014-04-01

    Simulations with a general circulation model (GCM) demonstrated that wind and temperature above the Martian mesopause (~100 km) respond to global dust storms as intensively as in the lower atmosphere. During the equinoctial dust storm, temperature decreased above 100 km by up to 30K, except in the northern high latitudes, where it increased by ~15 K. At the solstitial dust storm, temperature dropped by 40 K in the winter hemisphere, by ~15 K in the summer hemisphere, and increased by 30-40 K in tropics. Zonal wind jets intensified throughout the atmosphere at all heights. The changes are the result of altering the meridional circulation by atmospheric waves of different scales.

  14. Investigation of Ring Current Response to CIR-Driven Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Cramer, William Douglas

    The physics of ring current behavior during Coronal Mass Ejection (CME)-driven storms is well understood and can be modeled with moderate accuracy. The effects of Corotating Interaction Region (CIR)-driven storms are less understood and tend to not agree with expected values. Various approaches are employed to examine the differences in ring current behavior during storms driven by these two types of events. Satellite data (Polar CAM-MICE/MICS) are analyzed to determine differences in pitch angle distributions and energy densities, in order to provide insight into how the various ring current enhancement and loss processes differ during the different types of events. A ring current model (the Comprehensive Ring Current Model) is also employed to analyze these differences by modeling ring current behavior during CME and CIR events that fit a typical solar wind profile. No differences in convection were noted in satellite data during CME and CIR-driven storms of similar strength, although oxygen was found to contribute more to the energy density during CIRs. However, model results demonstrated that there is a significant difference in ring current response during storms associated with the different drivers. It was determined that particle convection appears to be the primary ring current energization mechanism for CME-driven events, while other factors seem to influence the induced surface magnetic disturbance during CIR-driven storms; possibly boundary conditions, external currents or fluctuations caused by the associated wave-induced oscillations in the solar wind.

  15. Extreme Helicity and Intense Convective Towers in Hurricane Bonnie

    NASA Technical Reports Server (NTRS)

    Molinari, John; Vollaro, David

    2008-01-01

    Helicity was calculated in Hurricane Bonnie (1998) using tropospheric-deep dropsonde soundings from the NASA Convection and Moisture Experiment. Large helicity existed downshear of the storm center with respect to the ambient vertical wind shear. It was associated with veering, semicircular hodographs created by strong, vortex-scale, radial-vertical flow induced by the shear. The most extreme values of helicity, among the largest ever reported in the literature, occurred in the vicinity of deep convective cells in the downshear-left quadrant. These cells reached as high as 17.5 km and displayed the temporal and spatial scales of supercells. Convective available potential energy (CAPE) averaged 861 J/kg downshear, but only about one-third as large upshear. The soundings nearest the deep cells were evaluated using two empirical supercell parameters that make use of CAPE, helicity, and/or shear. These parameters supported the possible existence of supercells as a consequence of the exceptional helicity combined with moderate but sufficient CAPE. Ambient vertical wind shear exceeded 12 m/s for 30 h, yet the hurricane maintained 50 m/s maximum winds. It is hypothesized that the long-lived convective cells enabled the storm to resist the negative impact of the shear. Supercells in large-helicity, curved-hodograph environments appear to provide a useful conceptual model for intense convection in the hurricane core. Helicity calculations might also give some insight into the behavior of vortical hot towers, which share some characteristics with supercells.

  16. Convective Structure Observed from HIWRAP During MC3E

    NASA Astrophysics Data System (ADS)

    Heymsfield, G. M.; Tian, L.; Li, L.; Mclinden, M.; Reynolds, A.; Cervantes, J.

    2011-12-01

    The High-altitude Imaging Wind and Rain Profiler (HIWRAP) was configured to fly on the high-altitude NASA ER-2 during Mid-Latitude Continental Convective Clouds Experiment (MC3E) in support of Global Precipitation Mission (GPM) Ground Validation algorithm development. HIWRAP-ER2 is a dual-frequency (Ku, Ka-band) nadir pointing Doppler radar. While our specific objectives were to get data sets for GPM algorithm development, the HIWRAP data provided excellent vertical cross sections through a variety of convective and stratiform systems that were near or within the enhanced Southern Great Plains (SGP) network. In this presentation, we provide preliminary analyses of HIWRAP observations along with coordinated ground-based radar coverage when available. The focus will be on a.) general structural characteristics of the convection, and b.) dual frequency reflectivity and Doppler measurements and their implications on the microphysical structure of the storms. The convective structure during MC3E will be compared with tropical and subtropical convective storms previously studied with the high-altitude radar measurements.

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

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Ingersoll, A. P.

    2013-10-01

    A giant planet-encircling storm occured on Saturn at the end of year 2010. The storm produced lightning at a rate greater than 10 SEDs per second. It wrapped around the planet, with a wake depleted in ammonia, 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 on the development of the storm and explain the observed post-storm ammonia depletion. The study is composed of two parts. First, thermodynamcis on Saturn indicates that strong convection is prohibited by the waterloading-effect when the troposphere is warm. After 20-30 years, the troposphere has cooled below a critical value so that deep convection develops at the base of the water cloud. The deep water mixing ratio is best estimated as 1.2% relative to H2 so as to match the cooling time. Second, strong convection can produce a warm convective column that overshoots into the stratosphere. We solve the cylindrically symmetric hydrostatic primitive equations to investigate the large scale response of the ambient flow to the geostrophically unbalanced column. We find that during the subsequent large scale adjustment, ammonia vapor condenses and precipitates out of the troposphere, causing high residual brightness temperatures as observed by Cassini/RADAR (Janssen et al., 2013; Laraia et al., 2013). Further, for a deep water mixing ratio of 1.2%, we find that the ammonia vapor is depeleted down to 5 bar, that the speed of remaining anticyclonic vortex is about 30 m/s, and the residual large scale warming is about 10 K. These values are consistent with observation within the measurement uncertainties.

  18. Summer Programs for Educators

    ERIC Educational Resources Information Center

    Curriculum Review, 2009

    2009-01-01

    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…

  19. Summer Library Reading Programs

    ERIC Educational Resources Information Center

    Fiore, Carole D.

    2007-01-01

    Virtually all public libraries in the United States provide some type of summer library reading program during the traditional summer vacation period. Summer library reading programs provide opportunities for students of many ages and abilities to practice their reading skills and maintain skills that are developed during the school year. Fiore…

  20. Slithering into Summer

    ERIC Educational Resources Information Center

    Scott, Catherine; Matthews, Catherine

    2012-01-01

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

  1. Slowing the Summer Slide

    ERIC Educational Resources Information Center

    Smith, Lorna

    2012-01-01

    Research shows that summer slide--the loss of learning over the summer break--is a huge contributor to the achievement gap between low-income students and their higher-income peers. In fact, some researchers have concluded that two-thirds of the 9th-grade reading achievement gap can be explained by unequal access to summer learning opportunities…

  2. Summer Correspondence Program.

    ERIC Educational Resources Information Center

    Sulphur Springs Union Elementary School District, Canyon Country, CA.

    THE FOLLOWING IS THE FULL TEXT OF THIS DOCUMENT: The goals of the Summer Correspondence Program have been to help students maintain their basic skills and avoid summer fall-out, as well as to promote parent involvement and positive community relations. After Proposition 13 left no funds for continuation of summer school programs, Sulphur Springs…

  3. Booktalking: Avoiding Summer Drift

    ERIC Educational Resources Information Center

    Whittingham, Jeff; Rickman, Wendy A.

    2015-01-01

    Summer drift, otherwise known as loss of reading comprehension skills or reading achievement, has been a well-known and well-documented phenomenon of public education for decades. Studies from the late twentieth century to the present have demonstrated a slowdown in summer drift attributed to specific summer reading programs addressing motivation…

  4. Summer Programs for Educators

    ERIC Educational Resources Information Center

    Curriculum Review, 2009

    2009-01-01

    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

  5. Role of wetlands in attenuation of storm surges using coastal circulation model (ADCIRC), Chesapeake Bay region

    NASA Astrophysics Data System (ADS)

    Deb, Mithun; Ferreira, Celso; Lawler, Seth

    2014-05-01

    The Chesapeake Bay, Virginia is subject to storm surge from extreme weather events nearly year-round; from tropical storms and hurricanes during the summer and fall, (e.g., hurricanes Isabel [2003] and Sandy [2012]), and from nor'easters during the winter (e.g., winter storms Nemo and Saturn [2013]). Coastal wetlands can deliver acute fortification against incoming hurricane storm surges. Coastal wetlands and vegetation shape the hydrodynamics of storm surge events by retaining water and slowing the propagation of storm surge, acting as a natural barrier to flooding. Consequently, a precise scheme to quantify the effect of wetlands on coastal surge levels was also prerequisite. Two wetland sites were chosen in the Chesapeake Bay region for detailed cataloging of vegetation characteristics, including: height, stem diameter, and density. A framework was developed combining these wetlands characterizations with numerical simulations. Storms surges were calculated using Coastal circulation model (ADCIRC) coupled to a wave model (SWAN) forced by an asymmetric hurricane vortex model using an unstructured mesh (comprised of 1.8 million nodes) under a High Performance Computing environment. The Hurricane Boundary Layer (HBL) model was used to compute wind and pressure fields for historical tropical storms and for all of the synthetic storms. Wetlands were characterized in the coupled numerical models by bathymetric and frictional resistance. Multiple model simulations were performed using historical hurricane data and hypothetical storms to compare the predicted storm surge inundation resulting from various levels of wetlands expansion or reduction. The results of these simulations demonstrate the efficacy of wetlands in storm surge attenuation and also the outcome will scientifically support planning of wetlands restoration projects with multi-objective benefits for society.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  8. Mechanisms of nutrient export in storm water runoff from catchments

    NASA Astrophysics Data System (ADS)

    Lewis, D. B.; Grimm, N. B.

    2003-04-01

    Regulatory policies aimed at preventing degradation of water resources benefit from understanding the processes that create water pollution. Understanding these processes requires determining what controls material export from the catchments that drain into the water bodies of interest. Export may vary through time, may vary among different land covers, and may derive from several vectors. Here, we focus on nutrients exported in storm water runoff from catchments in urban ecosystems. In the desert metropolis of Phoenix, Arizona, USA, we investigated whether features of storms and catchment land cover influenced the chemistry of runoff. We observed substantial variation in the load of nutrients exported in storm water. In runoff from single events, total nitrogen (TN) load ranged from 18 - 1147 g / ha, and total phosphorus (TP) load ranged from 3 - 266 g / ha. We hypothesized that this variation derived from variation in (i) storm activity, (ii) meteorological conditions preceding the storm, and (iii) catchment land cover. We found support for all hypotheses, though much variation remained unexplained. (i) Loads of TN and TP were positively correlated with precipitation intensity and with total precipitation. (ii) Loads were also positively correlated with the number of rainless days preceding the storm. Loads did not differ, however, between the types of climatic systems (summer monsoon vs. winter cold front) generating the storms. (iii) Loads positively correlated with housing density at both the metropolitan and continental scales. Variation in runoff chemistry was much greater among storms, however, than it was among different types of catchments. The biological consequences of nutrient flux from catchments to aquatic systems may be governed as much by nutrient ratios as by total nutrient loads. Thus, we also investigated mechanisms that produced variation in nutrient ratios in storm-water runoff. Molar N:P ratios ranged from 4 - 279, and were positively correlated with housing density. None of the other hypotheses explained variation in N:P ratios. Collectively, these results suggest that features of storms and urban design can exert a strong influence on the material exported from catchments to water bodies. The large amount of unexplained variance in export, however, warrants understanding the mechanisms by which nutrients are deposited onto to catchments in the first place.

  9. Interannual Behavior of Large Regional Dust Storms

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  10. Ionospheric redistribution during geomagnetic storms

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  11. Outreach Plans for Storm Peak Laboratory

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  12. Moist convection of Neptune

    SciTech Connect

    Stoker, C.R.; Toon, O.B. )

    1989-08-01

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

  13. Mars Atmospheric Chemistry in Electrified Dust Devils and Storms

    NASA Technical Reports Server (NTRS)

    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

    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.

  14. Record-breaking storm activity on Uranus in 2014

    NASA Astrophysics Data System (ADS)

    de Pater, Imke; Sromovsky, L. A.; Fry, P. M.; Hammel, Heidi B.; Baranec, Christoph; Sayanagi, Kunio M.

    2015-05-01

    In spite of an expected decline in convective activity following the 2007 equinox of Uranus, eight sizable storms were detected on the planet with the near-infrared camera NIRC2, coupled to the adaptive optics system, on the 10-m W.M. Keck telescope on UT 5 and 6 August 2014. All storms were on Uranus' northern hemisphere, including the brightest storm ever seen in this planet at 2.2 μm, reflecting 30% as much light as the rest of the planet at this wavelength. The storm was at a planetocentric latitude of ∼15°N and reached altitudes of ∼330 mbar, well above the regular uppermost cloud layer (methane-ice) in the atmosphere. A cloud feature at a latitude of 32°N, that was deeper in the atmosphere (near ∼2 bar), was later seen by amateur astronomers. We also present images returned from our HST ToO program, that shows both of these cloud features. We further report the first detection of a long-awaited haze over the north polar region.

  15. Martian dust storms as a possible sink of atmospheric methane

    NASA Astrophysics Data System (ADS)

    Farrell, W. M.; Delory, G. T.; Atreya, S. K.

    2006-11-01

    Recent laboratory tests, analog studies and numerical simulations all suggest that Martian dust devils and larger dusty convective storms generate and maintain large-scale electric fields. Such expected E-fields will have the capability to create significant electron drift motion in the collisional gas and to form an extended high energy (u $\\gg$ kT) electron tail in the distribution. We demonstrate herein that these energetic electrons are capable of dissociating any trace CH4 in the ambient atmosphere thereby acting as an atmospheric sink of this important gas. We demonstrate that the methane destruction rate increases by a factor of 1012 as the dust storm E-fields, E, increase from 5 to 25 kV/m, resulting in an apparent decrease in methane stability from ~ 1010 sec to a value of ~1000 seconds. While destruction in dust storms is severe, the overall methane lifetime is expected to decrease only moderately due to recycling of products, heterogeneous effects from localized sinks, etc. We show further evidence that the electrical activity anticipated in Martian dust storms creates a new harsh electro-chemical environment.

  16. Balanced dynamics and convection in the tropical troposphere

    NASA Astrophysics Data System (ADS)

    Raymond, David; Fuchs, Željka; Gjorgjievska, Saška; Sessions, Sharon

    2015-09-01

    This paper presents a conceptual picture of balanced tropical tropospheric dynamics inspired by recent observations. The most important factor differentiating the tropics from middle and higher latitudes is the absence of baroclinic instability; upward motion occurs primarily via deep convective processes. Thus, convection forms an integral part of large-scale tropical motions. Since convection itself is small-scale and chaotic in detail, predictability lies in uncovering the hidden hands that guide the average behavior of convection. Two appear, balanced dynamics and thermodynamic constraints. Contrary to conventional expectations, balanced dynamics plays a crucial role in the tropical atmosphere. However, due to the smallness of the Coriolis parameter there, nonlinear balance is more important in the tropics than at higher latitudes. Three thermodynamic constraints appear to play an important role in governing the average behavior of convection outside of the cores of tropical storms. First, convection is subject to control via a lower tropospheric buoyancy quasi-equilibrium process, wherein destabilization of the lower troposphere by nonconvective processes is balanced by convective stabilization. Second, the production of precipitation is extraordinarily sensitive to the saturation fraction of the troposphere. Third, "moisture quasi-equilibrium" governs the saturation fraction, with moister atmospheres being associated with smaller moist convective instability. The moist convective instability is governed by the balanced thermodynamic response to the pattern of potential vorticity, which in turn is slowly modified by convective and radiative heating. The intricate dance between these dynamic and thermodynamic processes leads to complex behavior of the tropical atmosphere in ways that we are just beginning to understand.

  17. Extreme Lightning Flash Rates as an Early Indicator of Severe Storms

    NASA Technical Reports Server (NTRS)

    Goodman, Steven J.; Arnold, James E. (Technical Monitor)

    2002-01-01

    Extreme lightning flash rates are proving to be an early indicator of intensifying storms capable of producing tornadoes, damaging winds and hail. Most of this lightning is in the cloud, where the naked eye can not see it. Recent global observations of thunderstorms from space indicate that giant electrical storms (supercells and convective complexes) with flash rates on the order of 1 flash per second are most common over the land masses of the America sub-tropics and equatorial Congo Basin. Within the United States, the average tornado warning lead time on a national basis is about 11 min. The real-time observation of extreme flash rates and the rapid increase in the in-cloud flash rate, signalling the intensification of the storm updraft, may provide as much as a 50% increase in severe storm warning lead time.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

  19. Comparison of Rainfall Characteristics and Convective Properties of Monsoon Precipitation Systems over South China and Yangtze-and-Huai River Basin

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Wang, H.; Zhang, R.; Qian, W.; Luo, Z.

    2012-04-01

    Rainfall characteristics and convective properties of monsoon precipitation systems over the South China (SC) and the Yangtze-and-Huai River Basin (YHRB) are investigated by combining a gridded daily precipitation data product based on surface station observations, a Tropical Rainfall Measuring Mission dataset, the CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations data products. Atmospheric aerosol amounts are inferred using a Moderate Resolution Imaging Spectroradiometer aerosol product. Comparison between the two regions is made for their monsoon active periods to reveal variations of the monsoon precipitation systems along with the northward march of the East Asian summer monsoon rainbelt from the SC to the YHRB. Relative to the YHRB, precipitation systems over the SC occur more frequently, resulting in larger maxima of the monsoon rainfall accumulation, but the SC systems are convectively less intense which is linked to the contrasts in strength of low-level vortices and surface fronts between the two regions. Contrasting among the pre-monsoon, monsoon active and break, and post-monsoon periods is also conducted for each region to unveil intraseasonal transitions of the precipitation systems, atmospheric conditions, and weather systems. Convective activities of the precipitation systems enhance progressively from the pre-monsoon to the monsoon and further to the post-monsoon period at both regions with more significant convection intensification from the pre-monsoon to the monsoon period at the YHRB, being largely in agreement with the intraseasonal variations of atmospheric thermodynamic conditions (convective available potential energy). From the pre-monsoon to the monsoon periods, the lightning flash rates decrease substantially at the SC, in contrast to the YHRB where the rates increase slightly. While aerosol loading is in favor of electrification during the pre-monsoon periods at both regions, the convective strength of the YHRB pre-monsoon is too weak to boost up lightning activity. The SC region, on the other hand, has more similar convective intensity from the pre-monsoon to the active monsoon, so aerosol effect stands out. Moreover, horizontal extents of precipitation systems are larger (smaller) on average during the monsoon active and pre-monsoon (post-monsoon and break) periods, which can be largely explained by the scale difference of the driving mechanisms: the precipitation storms are less controlled by large-scale weather systems (dynamically driven) but more by local instability due to solar heating (thermodynamically driven) during the post-monsoon and break periods.

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

    NASA Astrophysics Data System (ADS)

    Shirley, James H.

    2015-05-01

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

  1. Winter Storm Zones on Mars

    NASA Technical Reports Server (NTRS)

    Hollingsworth, J. L.; Haberle, R. M.; Barnes, J. R.; Bridger, A. F. C.; Cuzzi, Jeffrey N. (Technical Monitor)

    1995-01-01

    Preferred regions of weather activity in Mars' winter middle latitudes-so called 'storm zones' are found in a general circulation model of Mars' atmospheric circulation. During northern winter, these storm zones occur in middle latitudes in the major planitia (low-relief regions) of the western and eastern hemisphere. In contrast, the highlands of the eastern hemisphere are mostly quiescent. Compared to Earth's storm zones where diabatic heating associated with land-sea thermal contrasts is crucial, orography on Mars is fundamental to the regionalization of weather activity. Future spacecraft missions aimed at assessing Mars' climate and its variability need to include such regions in observation strategies.

  2. Centralized Storm Information System (CSIS)

    NASA Technical Reports Server (NTRS)

    Norton, C. C.

    1985-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  4. A density-temperature description of the outer electron radiation belt during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Denton, Michael H.; Borovsky, Joseph E.; Cayton, Thomas E.

    2010-01-01

    Bi-Maxwellian fits are made to energetic-electron flux measurements from seven satellites in geosynchronous orbit, yielding a number density (n) and temperature (T) description of the outer electron radiation belt. For 54.5 spacecraft years of measurements the median value of n is 3.7 × 10-4 cm-3, and the median value of T is 148 keV. General statistical properties of n, T, and the 1.1-1.5 MeV flux F are investigated, including local-time and solar-cycle dependencies. Using superposed-epoch analysis where the zero epoch is convection onset, the evolution of the outer electron radiation belt through high-speed-stream-driven storms is investigated. The number-density decay during the calm before the storm, relativistic-electron dropouts and recoveries, and the heating of the outer electron radiation belt during storms are analyzed. Using four different "triggers" (sudden storm commencement (SSC), southward interplanetary magnetic field (IMF) portions of coronal mass ejection (CME) sheaths, southward-IMF portions of magnetic clouds, and minimum Dst) a selection of CME-driven storms are analyzed with superposed-epoch techniques. For CME-driven storms, only a very modest density decay prior to storm onset is found. In addition, the compression of the outer electron radiation belt at the time of SSC is analyzed, the number-density increase and temperature decrease during storm main phase are characterized, and the increase in density and temperature during storm recovery phase is determined. During the different phases of storms, changes in the flux are sometimes in response to changes in the temperature, sometimes to changes in the number density, and sometimes to changes in both. Differences are found between the density-temperature and flux descriptions, and it is concluded that more information is available using the density-temperature description.

  5. On the contribution of plasma sheet bubbles to the storm time ring current

    NASA Astrophysics Data System (ADS)

    Yang, Jian; Toffoletto, Frank R.; Wolf, Richard A.; Sazykin, Stanislav

    2015-09-01

    Particle injections occur frequently inside 10 Re during geomagnetic storms. They are commonly associated with bursty bulk flows or plasma sheet bubbles transported from the tail to the inner magnetosphere. Although observations and theoretical arguments have suggested that they may have an important role in storm time dynamics, this assertion has not been addressed quantitatively. In this paper, we investigate which process is dominant for the storm time ring current buildup: large-scale enhanced convection or localized bubble injections. We use the Rice Convection Model-Equilibrium (RCM-E) to model a series of idealized storm main phases. The boundary conditions at 14-15 Re on the nightside are adjusted to randomly inject bubbles to a degree roughly consistent with observed statistical properties. A test particle tracing technique is then used to identify the source of the ring current plasma. We find that the contribution of plasma sheet bubbles to the ring current energy increases from ~20% for weak storms to ~50% for moderate storms and levels off at ~61% for intense storms, while the contribution of trapped particles decreases from ~60% for weak storms to ~30% for moderate and ~21% for intense storms. The contribution of nonbubble plasma sheet flux tubes remains ~20% on average regardless of the storm intensity. Consistent with previous RCM and RCM-E simulations, our results show that the mechanisms for plasma sheet bubbles enhancing the ring current energy are (1) the deep penetration of bubbles and (2) the bulk plasma pushed ahead of bubbles. Both the bubbles and the plasma pushed ahead typically contain larger distribution functions than those in the inner magnetosphere at quiet times. An integrated effect of those individual bubble injections is the gradual enhancement of the storm time ring current. We also make two predictions testable against observations. First, fluctuations over a time scale of 5-20 min in the plasma distributions and electric field can be seen in the central ring current region for the storm main phase. We find that the plasma pressure and the electric field EY there vary over about 10%-30% and 50%-300% of the background values, respectively. Second, the maximum plasma pressure and magnetic field depression in the central ring current region during the main phase are well correlated with the Dst index.

  6. Stochastic Convection Parameterizations

    NASA Technical Reports Server (NTRS)

    Teixeira, Joao; Reynolds, Carolyn; Suselj, Kay; Matheou, Georgios

    2012-01-01

    computational fluid dynamics, radiation, clouds, turbulence, convection, gravity waves, surface interaction, radiation interaction, cloud and aerosol microphysics, complexity (vegetation, biogeochemistry, radiation versus turbulence/convection stochastic approach, non-linearities, Monte Carlo, high resolutions, large-Eddy Simulations, cloud structure, plumes, saturation in tropics, forecasting, parameterizations, stochastic, radiation-clod interaction, hurricane forecasts

  7. Latitudinal and Seasonal Investigations of Storm-Time TEC Variation

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    The ionosphere responds markedly and unpredictably to varying magnetospheric energy inputs caused by solar disturbances on the geospace. Knowledge of the impact of the space weather events on the ionosphere is important to assess the environmental effect on the operations of ground- and space-based technologies. Thus, global positioning system (GPS) measurements from the international GNSS service (IGS) database were used to investigate the ionospheric response to 56 geomagnetic storm events at six different latitudes comprising the northern and southern hemispheres in the Afro-European sector. Statistical distributions of total electron content (TEC) response show that during the main phase of the storms, enhancement of TEC is more pronounced in most of the seasons, regardless of the latitude and hemisphere. However, a strong seasonal dependence appears in the TEC response during the recovery phase. Depletion of TEC is majorly observed at the high latitude stations, and its appearance at lower latitudes is seasonally dependent. In summer hemisphere, the depletion of TEC is more pronounced in nearly all the latitudinal bands. In winter hemisphere, enhancement as well as depletion of TEC is observed over the high latitude, while enhancement is majorly observed over the mid and low latitudes. In equinoxes, the storm-time TEC distribution shows a fairly consistent characteristic with the summer distribution, particularly in the northern hemisphere.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  10. Computer Summer Camp.

    ERIC Educational Resources Information Center

    Zabinski, Toby F.; Zabinski, Michael P.

    1979-01-01

    Describes the objectives, organization, and daily activities of a youth summer camp program providing general knowledge about computers, computing, social implications of computers, and opportunities for careers. (CMV)

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

    SciTech Connect

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

    2008-12-01

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

  12. Riding the storm out

    NASA Astrophysics Data System (ADS)

    Wurman, Josh

    2009-04-01

    I am standing on a bridge near the North Carolina coast. There is a light breeze, and I am enjoying some hazy sunshine. But this calm is an illusion: in a few minutes winds of up to 45ms-1 (100 mph) will sweep in again. The approaches to my section of the bridge are already drowned under 2.5 m of water, and my companions on this island are an eclectic mix of traumatized animals, including snakes, rats, wounded pelicans and frogs. Earlier, one of the snakes flew through the air past my truck. The animals and I have been drawn to this bridge by Hurricane Isabel, which has just slammed into the coastal islands of North Carolina, and at the moment we are in the calm, sunny eye of the storm. The animals are just trying to survive on the area's only dry ground. But I have come to the bridge with a radar system on a truck and have spent a night and a day on it because I want to know what is happening inside this hurricane.

  13. Cocaine Intoxication and Thyroid Storm

    PubMed Central

    Lacy, Mary E.

    2014-01-01

    Introduction. Cocaine, a widely used sympathomimetic drug, causes thermoregulatory and cardiac manifestations that can mimic a life-threatening thyroid storm. Case. A man presented to the emergency department requesting only cocaine detoxification. He reported symptoms over the last few years including weight loss and diarrhea, which he attributed to ongoing cocaine use. On presentation he had an elevated temperature of 39.4°C and a heart rate up to 130 beats per minute. Examination revealed the presence of an enlarged, nontender goiter with bilateral continuous bruits. He was found to have thyrotoxicosis by labs and was treated for thyroid storm and cocaine intoxication concurrently. The patient was ultimately diagnosed with Graves’ disease and treated with iodine-131 therapy. Conclusion. Cocaine use should be considered a possible trigger for thyroid storm. Recognition of thyroid storm is critical because of the necessity for targeted therapy and the significant mortality associated with the condition if left untreated. PMID:26425625

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  15. Toward an integrated storm surge application: ESA Storm Surge project

    NASA Astrophysics Data System (ADS)

    Lee, Boram; Donlon, Craig; Arino, Olivier

    2010-05-01

    Storm surges and their associated coastal inundation are major coastal marine hazards, both in tropical and extra-tropical areas. As sea level rises due to climate change, the impact of storm surges and associated extreme flooding may increase in low-lying countries and harbour cities. Of the 33 world cities predicted to have at least 8 million people by 2015, at least 21 of them are coastal including 8 of the 10 largest. They are highly vulnerable to coastal hazards including storm surges. Coastal inundation forecasting and warning systems depend on the crosscutting cooperation of different scientific disciplines and user communities. An integrated approach to storm surge, wave, sea-level and flood forecasting offers an optimal strategy for building improved operational forecasts and warnings capability for coastal inundation. The Earth Observation (EO) information from satellites has demonstrated high potential to enhanced coastal hazard monitoring, analysis, and forecasting; the GOCE geoid data can help calculating accurate positions of tide gauge stations within the GLOSS network. ASAR images has demonstrated usefulness in analysing hydrological situation in coastal zones with timely manner, when hazardous events occur. Wind speed and direction, which is the key parameters for storm surge forecasting and hindcasting, can be derived by using scatterometer data. The current issue is, although great deal of useful EO information and application tools exist, that sufficient user information on EO data availability is missing and that easy access supported by user applications and documentation is highly required. Clear documentation on the user requirements in support of improved storm surge forecasting and risk assessment is also needed at the present. The paper primarily addresses the requirements for data, models/technologies, and operational skills, based on the results from the recent Scientific and Technical Symposium on Storm Surges (www.surgesymposium.org, organized by the WMO-IOC Joint technical Commission for Oceanography and Marine Meteorology, JCOMM) and following activities, that have been supported by the Intergovernmental Oceanographic Commission (IOC) of UNESCO through JCOMM. The paper also reviews the capabilities of storm surge models, and current status in using Earth Observation (EO) information for advancing storm surge application tools, and further, for improving operational forecasts and warning capability for coastal inundation. In this context, the plans and expected results of the ESA Storm Surge Project (2010-2011) will be introduced.

  16. Ionospheric redistribution during geomagnetic storms

    PubMed Central

    Immel, T J; Mannucci, A J

    2013-01-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (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. PMID:26167429

  17. Magnetic Storms and Induction Hazards

    NASA Astrophysics Data System (ADS)

    Love, Jeffrey J.; Joshua Rigler, E.; Pulkkinen, Antti; Balch, Christopher C.

    2014-12-01

    Magnetic storms are potentially hazardous to the activities and technological infrastructure of modern civilization. This reality was dramatically demonstrated during the great magnetic storm of March 1989, when surface geoelectric fields, produced by the interaction of the time-varying geomagnetic field with the Earth's electrically conducting interior, coupled onto the overlying Hydro-Qubec electric power grid in Canada. Protective relays were tripped, the grid collapsed, and about 9 million people were temporarily left without electricity [Bolduc, 2002].

  18. Magnetic storms and induction hazards

    USGS Publications Warehouse

    Love, Jeffrey J.; Rigler, E. Joshua; Pulkkinen, Antti; Balch, Christopher

    2014-01-01

    Magnetic storms are potentially hazardous to the activities and technological infrastructure of modern civilization. This reality was dramatically demonstrated during the great magnetic storm of March 1989, when surface geoelectric fields, produced by the interaction of the time-varying geomagnetic field with the Earth's electrically conducting interior, coupled onto the overlying Hydro-Québec electric power grid in Canada. Protective relays were tripped, the grid collapsed, and about 9 million people were temporarily left without electricity [Bolduc, 2002].

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Li, C.; Ingersoll, A. P.

    2014-12-01

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

  1. Severe storm identification with satellite microwave radiometry: An initial investigation with Nimbus-7 SMMR data

    NASA Technical Reports Server (NTRS)

    Spencer, R. W.; Howland, M. R.

    1984-01-01

    The severe weather characteristics of convective storms as observed by the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) are investigated. Low 37 GHz brightness temperatures (due to scattering of upwelling radiation by precipitation size ice) are related to the occurrence of severe weather (large hail, strong winds or wind damage, tornadoes and funnel clouds) within one hour of the satellite observation time. During 1979 and 1980 over the United States there were 263 storms which had very cold 37 GHz signatures. Of these storms 15% were severe. The SMMR detected hail, wind, and tornadic storms equally well. Critical Success Indices (CSI's) of 0.32, 0.48, and 0.38 are achieved for the thresholding of severe vs. nonsevere low brightness temperature events during 1979, 1980, and the two years combined, respectively. Such scores are comparable to skill scores for early radar detection methods. These results suggest that a future geostationary passive microwave imaging capability at 37 GHz, with sufficient spatial and temporal resolution, would allow the detection of severe convective storms. This capability would provide a useful complement to radar, especially in areas not covered by radar.

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

    PubMed

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

    2011-07-01

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

  3. Magneto-convection.

    PubMed

    Stein, Robert F

    2012-07-13

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

  4. Celebrate Summer with Reading

    ERIC Educational Resources Information Center

    Texley, Juliana

    2007-01-01

    School is out and the summer is full of both official and unofficial holidays that prompt us to enjoy science and the profession of sharing it. As in past years, the reviewers and editors of "NSTA Recommends"--ready and willing to share their enthusiasm for reading with you--have been gathering suggestions for the summer. So along with your beach

  5. Your Best Summer Ever

    ERIC Educational Resources Information Center

    Cleaver, Samantha

    2012-01-01

    "It must be nice to have summers off." Only other teachers know just how short summer is, with much of August devoted to planning for the new school year. This article offers 17 fresh ideas for exploring, making money, and preparing for next year. Plus, a reading list that hits all the marks!

  6. Science in the Summer.

    ERIC Educational Resources Information Center

    Redmond, Alan

    2000-01-01

    Describes a summer program called Science in the Summer (SitS). The goal of this 9-year program is to encourage students to engage in science learning. Presents beginner and advanced level activities focusing on chemistry and engineering. Summarizes student evaluations on the program along with a breakdown of the SitS 1999 program. (SAH)

  7. Special Summer Section.

    ERIC Educational Resources Information Center

    G/C/T, 1981

    1981-01-01

    The section on summer programs for the gifted includes a directory of 62 programs and eight brief articles on independent learning; Project IDEA, a psychomotor program; miscellaneous offerings; The College Academy, Framingham College, MA; The College for Kids Project, IL; environmental education; an animal behavior course; and a summer academy.…

  8. Choosing Academic Summer Programs.

    ERIC Educational Resources Information Center

    Hellerman, Susan B., Ed.

    1994-01-01

    This newsletter theme issue deals with summer program offerings for academically talented youth. It notes the benefits of summer programs and outlines factors to consider in choosing the most appropriate one. Several types of programs are then described, including talent search programs, young students programs, math programs, science programs,…

  9. Celebrate Summer with Reading

    ERIC Educational Resources Information Center

    Texley, Juliana

    2007-01-01

    School is out and the summer is full of both official and unofficial holidays that prompt us to enjoy science and the profession of sharing it. As in past years, the reviewers and editors of "NSTA Recommends"--ready and willing to share their enthusiasm for reading with you--have been gathering suggestions for the summer. So along with your beach…

  10. Book Your Summer Vacation

    ERIC Educational Resources Information Center

    Texley, Juliana

    2012-01-01

    Summer's the time for teachers to travel, not only physically from the confines of the classroom to exotic places, but vicariously, through the magic of books. Summer adventures help teachers expand their experience and enrich their store of context so that they can offer their students more when school resumes in the fall. That's why each year…

  11. Under Summer Skies

    ERIC Educational Resources Information Center

    Texley, Juliana

    2009-01-01

    There's no better way to celebrate 2009, the International Year of Astronomy, than by curling up with a good book under summer skies. To every civilization, in every age, the skies inspired imagination and scientific inquiry. There's no better place to start your summer reading than under their influence. Here are a few selections identified by…

  12. Effects of explicit atmospheric convection at high CO2.

    PubMed

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

    2014-07-29

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

  13. Effects of explicit atmospheric convection at high CO2

    PubMed Central

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

    2014-01-01

    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

  14. Energy flux in the Earth's magnetosphere: Storm substorm relationship

    NASA Astrophysics Data System (ADS)

    Alexeev, Igor I.

    2003-04-01

    Three ways of the energy transfer in the Earth's magnetosphere are studied. The solar wind MHD generator is an unique energy source for all magnetospheric processes. Field-aligned currents directly transport the energy and momentum of the solar wind plasma to the Earth's ionosphere. The magnetospheric lobe and plasma sheet convection generated by the solar wind is another magnetospheric energy source. Plasma sheet particles and cold ionospheric polar wind ions are accelerated by convection electric field. After energetic particle precipitation into the upper atmosphere the solar wind energy is transferred into the ionosphere and atmosphere. This way of the energy transfer can include the tail lobe magnetic field energy storage connected with the increase of the tail current during the southward IMF. After that the magnetospheric substorm occurs. The model calculations of the magnetospheric energy give possibility to determine the ground state of the magnetosphere, and to calculate relative contributions of the tail current, ring current and field-aligned currents to the magnetospheric energy. The magnetospheric substorms and storms manifest that the permanent solar wind energy transfer ways are not enough for the covering of the solar wind energy input into the magnetosphere. Nonlinear explosive processes are necessary for the energy transmission into the ionosphere and atmosphere. For understanding a relation between substorm and storm it is necessary to take into account that they are the concurrent energy transferring ways.

  15. Ionospheric Storms in the Sub-Auroral Ionosphere: Local Time Effects Driven by Electrodynamics

    NASA Astrophysics Data System (ADS)

    Narvaez, C. L.; Mendillo, M.

    2009-12-01

    The response of the mid-latitude ionosphere to geomagnetic storms depends upon several pre-storm conditions, the dominant ones being season and local time of the storm commencement (SC). The difference between a site’s geographic and geomagnetic latitudes is also of major importance since it governs the blend of processes linked to solar production and magnetospheric input, respectively. Electrodynamics plays a central role in storm morphologies at sub-auroral sites: it contributes to the positive phase near dusk on the first day or a storm, and to the motions of the trough on subsequent nights, and to the Joule heating that drives the negative phase. To explore hemispheric consistency of ionospheric storms, we identify two key locations that are “geophysically-equivalent” sites and offer the optimal ways to assess magnetosphere-ionosphere coupling. At the longitudes of the dipole tilt, we use ionosonde values of the F2-layer maximum electron density (NmF2) to study geophysical equivalency at Wallops Island (VA) and Hobart (Tasmania), using statistical summaries of 206 events during solar cycle #20. We form average patterns of ΔNmF2 (%) versus local time over 7-day storm periods that are constructed in ways that enhance the portrayal of the characteristic features of the positive and negative phases of ionospheric storms. The results show a remarkable consistency between local time patterns of storm-induced perturbations and the processes that cause them in each hemisphere. Subtle differences are found in the role of electrodynamics for two features of the negative phase: convective motions of the trough and the Joule heating that drives the negative phase.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  17. What caused the rapid recovery of the Carrington storm?

    NASA Astrophysics Data System (ADS)

    Keika, Kunihiro; Ebihara, Yusuke; Kataoka, Ryuho

    2015-05-01

    The geomagnetic storm during the Carrington event, which occurred on 2 September 1859, displayed extremely rapid recovery. The geomagnetic field increased by approximately 650 nT/h at Bombay, India, and by >300 nT/h in 1-h averaged data. Although the rapid recovery is considered due to a sudden increase in the magnetopause current, a sudden decrease of the ring current, or/and a sudden enhancement of the ionospheric currents, this study focuses on the ring current decay. The Carrington rapid recovery had a time constant (approximately 1 h) comparable to the storm development (i.e., decrease in the geomagnetic field), indicating that energy loss from the ring current region is predominantly controlled by E × B convection transport which is responsible for energy input during the storm main phase. This feature has led us to a hypothesis that the flow-out of dense ring current ions and injections of tenuous plasma sheet ions caused the rapid decay of the ring current and in turn the storm rapid recovery. This study examines whether the Carrington rapid recovery can be explained by the flow-out effect. We extend the empirical Burton's model to a model that takes into consideration a sudden change in solar wind density which is correlated with plasma sheet density. We first apply the extended Burton's model to previously observed four intense magnetic storms (Dst minimum < -200 nT) for which solar wind data are available. Using the best fit parameters found by forward modeling, the extended model estimates the recovery of the Carrington storm. The estimate indicates that a solar wind structure with a density bump by approximately 100 cm-3 (and southward interplanetary magnetic field (IMF) of 65 nT and solar wind speed of 1,500 km/s) can cause the rapid recovery under a continuous southward IMF condition. We conclude that the flow-out effect plays a significant role in producing the rapid recovery of the Carrington storm.

  18. Chemical Evolution in Upper Tropospheric Convective Outflow: Case Study of a Mesoscale Convective System During DC3 (Invited)

    NASA Astrophysics Data System (ADS)

    Olson, J. R.; Crawford, J. H.; Diskin, G. S.; Sachse, G. W.; Blake, D. R.; Blake, N. J.; Brune, W. H.; Zhang, L.; Ren, X.; Mao, J.; Cohen, R. C.; Nault, B.; Dibb, J. E.; Cantrell, C. A.; Fried, A.; Richter, D.; Weibring, P.; Apel, E. C.; Flocke, F. M.; Hall, S. R.; Hornbrook, R. S.; Ullmann, K.; Weinheimer, A. J.; Hanisco, T. F.; Ryerson, T. B.; Crounse, J.; St Clair, J. M.; Wennberg, P. O.; Wisthaler, A.; Mikoviny, T.

    2013-12-01

    The jointly sponsored NSF/NASA/NOAA Deep Convective Clouds and Chemistry Project (DC3) took place during summer of 2012 to investigate the impact of deep convection over central North America on upper tropospheric composition and chemistry. On June 21, coordinated successive flights by the DC8 and GV aircraft successfully captured photochemical aging within and along the outflow of a decaying Mesoscale Convective System. Increases in ozone, HNO3, and PANs, accompanied by decreases in CH2O, NOx, VOCs and OVOCs are qualitatively consistent with persistent photochemistry for up to 12 daylight hours following the convective perturbations. The extended chemical processing is examined in detail using this rich data set and predictions of chemical evolution from the NASA LaRC Lagrangian photochemical box model, constrained with time varying observations of precursors along segments of the outflow.

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

    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 over very large areas. An overview of these new opportunities, mission goals and strategies will be hereby given and discussed.

  20. Convective dynamics - Panel report

    NASA Technical Reports Server (NTRS)

    Carbone, Richard; Foote, G. Brant; Moncrieff, Mitch; Gal-Chen, Tzvi; Cotton, William; Heymsfield, Gerald

    1990-01-01

    Aspects of highly organized forms of deep convection at midlatitudes are reviewed. Past emphasis in field work and cloud modeling has been directed toward severe weather as evidenced by research on tornadoes, hail, and strong surface winds. A number of specific issues concerning future thrusts, tactics, and techniques in convective dynamics are presented. These subjects include; convective modes and parameterization, global structure and scale interaction, convective energetics, transport studies, anvils and scale interaction, and scale selection. Also discussed are analysis workshops, four-dimensional data assimilation, matching models with observations, network Doppler analyses, mesoscale variability, and high-resolution/high-performance Doppler. It is also noted, that, classical surface measurements and soundings, flight-level research aircraft data, passive satellite data, and traditional photogrammetric studies are examples of datasets that require assimilation and integration.

  1. CONVECTION IN PLANETARY INTERIORS

    NASA Technical Reports Server (NTRS)

    Kopal, Z.

    1963-01-01

    Formulation of linearized equations safeguarding the conservation of mass, energy and momentum of viscous flow inside a fluid sphere, and application to the problem of convection in planetary interiors

  2. Tornadoes and severe storms in Spain

    NASA Astrophysics Data System (ADS)

    Gayà, Miquel

    2011-06-01

    A climatology of tornadoes, waterspouts, and straight winds linked to convection in Spain is presented. The database is divided into three periods according to the main source of information. The three distributions of severe weather are very sensitive to the sources of information, much more than to a possible change in climate. The early period, up to 1825, comprises cases that contain the real facts together with spurious inputs such as religion, myths, beliefs, etc, mixed in an unknown proportion. The period between 1826 and 1975, and the most recent one, up to 2009, enable us to observe geographical and temporal variations as a function of societal changes. The analysis of temporal and geographical distributions allows us to frame the risk in the face of severe storms, and the changes in their perception and management that have come about over time. Although the most recent tornadoes have been weak or strong, the Cádiz tornado of 1671 demonstrates that an extremely rare and violent event can occur in Spain. The large number of victims claimed by this tornado makes it one of the most important in the world.

  3. Evaluation of the STORM-Time Ionospheric Empirical Model for the Bastille Day event

    NASA Astrophysics Data System (ADS)

    Araujo-Pradere, E. A.; Fuller-Rowell, T. J.

    2001-12-01

    Recent theoretical model simulations of the ionospheric response to geomagnetic storms have provided the understanding for the development of an empirical storm-time ionospheric model (STORM). The empirical model is driven by the previous time-history of a p, and is designed to scale the quiet-time F-layer critical frequency (f o F 2) to account for storm-time changes in the ionosphere. The model provides a useful, yet simple tool for modeling of the perturbed ionosphere. The quality of the model prediction has been evaluated by comparing with the observed ionospheric response during the Bastille Day (July 2000) storm. With a maximum negative D st of -290 nT and an a p of 400, this magnetic perturbation was the strongest of year 2000. For these conditions, the model output was compared with the actual ionospheric response from all available stations, providing a reasonable latitudinal and longitudinal coverage. The comparisons show that the model captures the decreases in electron density particularly well in the northern summer hemisphere. In winter, the observed ionospheric response was more variable, showing a less consistent response, imposing a more severe challenge to the empirical model. The value of the model has been quantified by comparing the root mean square error (RMSE) of the STORM predictions with the monthly mean. The results of this study illustrate that the STORM model reduces the RMSE at the peak of the disturbance from 0.36 to 0.22, a significant improvement over climatology.

  4. A New Perspective on Southern Hemisphere Storm Tracks.

    NASA Astrophysics Data System (ADS)

    Hoskins, B. J.; Hodges, K. I.

    2005-10-01

    A detailed view of Southern Hemisphere storm tracks is obtained based on the application of filtered variance and modern feature-tracking techniques to a wide range of 45-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) data. It has been checked that the conclusions drawn in this study are valid even if data from only the satellite era are used. The emphasis of the paper is on the winter season, but results for the four seasons are also discussed. Both upper- and lower-tropospheric fields are used. The tracking analysis focuses on systems that last longer than 2 days and are mobile (move more than 1000 km). Many of the results support previous ideas about the storm tracks, but some new insights are also obtained. In the summer there is a rather circular, strong, deep high-latitude storm track. In winter the high-latitude storm track is more asymmetric with a spiral from the Atlantic and Indian Oceans in toward Antarctica and a subtropical jet related lower-latitude storm track over the Pacific, again tending to spiral poleward. At all times of the year, maximum storm activity in the higher-latitude storm track is in the Atlantic and Indian Ocean regions. In the winter upper troposphere, the relative importance of, and interplay between, the subtropical and subpolar storm tracks is discussed. The genesis, lysis, and growth rate of lower-tropospheric winter cyclones together lead to a vivid picture of their behavior that is summarized as a set of overlapping plates, each composed of cyclone life cycles. Systems in each plate appear to feed the genesis in the next plate through downstream development in the upper-troposphere spiral storm track. In the lee of the Andes in South America, there is cyclogenesis associated with the subtropical jet and also, poleward of this, cyclogenesis largely associated with system decay on the upslope and regeneration on the downslope. The genesis and lysis of cyclones and anticyclones have a definite spatial relationship with each other and with the Andes. At 500 hPa, their relative longitudinal positions are consistent with vortex-stretching ideas for simple flow over a large-scale mountain. Cyclonic systems near Antarctica have generally spiraled in from lower latitudes. However, cyclogenesis associated with mobile cyclones occurs around the Antarctic coast with an interesting genesis maximum over the sea ice near 150E. The South Pacific storm track emerges clearly from the tracking as a coherent deep feature spiraling from Australia to southern South America. A feature of the summer season is the genesis of eastward-moving cyclonic systems near the tropic of Capricorn off Brazil, in the central Pacific and, to a lesser extent, off Madagascar, followed by movement along the southwest flanks of the subtropical anticyclones and contribution to the convergence zone cloud bands seen in these regions.

  5. Mesoscale/convective interaction

    NASA Technical Reports Server (NTRS)

    Haines, P. A.; Sun, W. Y.

    1988-01-01

    A novel cumulus parameterization scheme (CPS) has been developed in order to account for mesoscale/convective-scale interaction which considers both the mesoscale and convective scale mass and moisture budgets, under the assumption that the heating rate is a maximum for given environmental conditions. The basis of the CPS is a detailed, quasi-one-dimensional cloud model that calculates mass and moisture fluxes similar to those calculated by the Schlesinger (1978) three-dimensional model.

  6. Nocturnal offshore convection near the island of Corsica

    NASA Astrophysics Data System (ADS)

    Barthlott, Christian; Adler, Bianca; Kalthoff, Norbert; Handwerker, Jan; Kohler, Martin; Wieser, Andreas

    2014-05-01

    In the region of Corsica, located in the western Mediterranean Sea, the mean daily lightning activity for late summer and autumn as an indicator for deep convection shows a distinct maximum in mid-afternoon and a secondary maximum in the night. During the night, most of the lightning activity is located offshore and near the island's coastline. Currently there are no observational data which could be used to explain this nocturnal offshore convection but understanding its formation mechanism is crucial for accurately forecasting the regional weather. In this work, we explore two possible mechanisms initiating nocturnal offshore convection: (i) convergence with subsequent lifting due to the interaction between drainage winds and the synoptic flow over the sea and (ii) dynamically induced lee-side convergence due to the island barrier effect. To this end, we perform numerical simulations with the Consortium for Small-scale Modeling (COSMO) model at a convection-resolving horizontal grid spacing of 2.8 km. The analysis of two cases with different low-level wind directions reveals that the role of the island's drainage flow can either favour or hinder the development of deep convection. Furthermore, convective initiation is very sensitive to terrain elevation and model initialisation time and small changes of these features can decide whether deep convection occurs or not.

  7. Mechanisms for Mars dust storms.

    NASA Technical Reports Server (NTRS)

    Leovy, C. B.; Zurek, R. W.; Pollack, J. B.

    1973-01-01

    Characteristics of the Mars global dust storm are reviewed. At the Mariner 9 encounter, the dust consisted of highly absorbing particles distributed rather uniformly up to great height (about 50 km). These observations together with temperature distributions inferred from the Mariner 9 IRIS by Hanel et al. (1972) are used to estimate global wind systems during the dust storm. The global distribution and direction of light surface streaks indicate that the axisymmetric circulation was a dominant part of flow during the dust storm. The axisymmetric winds may become strong enough to raise dust over wide areas of Mars' tropics under unusual conditions: the incoming solar radiation must be near its seasonal maximum, the static stability must be low, and the atmosphere must be able to absorb and re-emit a sizeable fraction of the incoming radiation. Strong winds around the periphery of the retreating south polar cap would be driven by the temperature gradient at the cap edge and by the mass outflow due to subliming CO2. These polar winds could generate local dust storms, raising the general level of dustiness, and providing the conditions necessary for onset of a global dust storm.

  8. Storm tracks near marginal stability

    NASA Astrophysics Data System (ADS)

    Ambaum, Maarten; Novak, Lenka

    2015-04-01

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

  9. IISME Summer Fellowship Program

    NASA Technical Reports Server (NTRS)

    1998-01-01

    During the summer of 1997, NASA-Ames scientists served as mentors to six teachers who worked as IISME (Industry Initiatives for Science and Math Education) Teacher Fellows over the summer. These six teachers were among 91 IISME Teacher Fellows working at various corporate, government agency, and university sites throughout the San Francisco Bay Area. These NASA-Ames fellowship positions are described in brief. One requirement of the IISME Summer Fellowship program is that teachers develop a personal Action Plan for classroom transfer. These Action Plans are published in abstract form in an annual catalog. I have also attached the abstracts of NASA-Ames teachers.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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)

  11. Mars' great storm of 1971.

    NASA Technical Reports Server (NTRS)

    Capen, C. F.; Martin, L. J.

    1972-01-01

    Description of the development of this planet-wide storm and its subsequent decline through mid-January 1972. The initial core of the disturbance extended northeast to southwest. Preliminary examination of photographic data indicates that the storm, yellow in color, spread completely around the planet in about 16 days. During the storm, red- and green-light photographs recorded Mars as brighter than normal, while in blue it was only slightly brighter, and in the ultraviolet there was no significant change. The history of yellow clouds is discussed. They seem to germinate in specific areas in the southern hemisphere, such as the Hellas-Noachis region. Another yellow cloud is predicted for July or August of 1973.

  12. Springtime North Polar Dust Storms

    NASA Technical Reports Server (NTRS)

    2002-01-01

    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.

  13. Intense geomagnetic storms: A study

    NASA Astrophysics Data System (ADS)

    Silbergleit, Virginia

    In the pipes and the lines of the transmission of the electrical energy, the route of the currents through them, causes a diminution of the life utility of the same one. The intense storms are studied, because these are induced quickly to the ionospheric systems that they change, obtaining great induced telluric currents (or GICs). Also the Akasofs parameter based on the time for periods of strong and moderate magnetic storms during the last 10 years is calculated. The method also standardizes the parameters of the storm: electron flow between 30-300 KeV, z component of the magnetic field (Bz), the solar Wind velocity (v), indices AE and AL. Also, the decay time of the ring current (which is different during the main and the recovery phase from of the geomagnetic disturbances) are calculated.

  14. Effects of chemistry on convective and non-convective precipitation over North Eastern North America

    NASA Astrophysics Data System (ADS)

    Mashayekhi, R.; Sloan, J. J.

    2013-12-01

    The change in convective and non-convective (microphysically-induced) precipitation due to the influence of chemistry - and particularly that of anthropogenic aerosols - is investigated in this study. The overall effect of chemistry is deduced from a comparison of the results from the Weather Research and Forecasting (WRF v3.4) model and its corresponding chemistry version (WRF/Chem v3.4). Simulations are conducted for a five-month period from April to August 2009 in a domain covering North Eastern North America with 12 km grid spacing. We created the temporally and spatially distributed anthropogenic emissions from area, point and mobile sources using the Sparse Matrix Operator Kernel Emissions (SMOKE v2.7) modeling system by processing the total annual county or province-based inventories for the U.S. and Canada using the appropriate temporal, chemical speciation and spatial surrogate cross-reference files. This study shows that convective precipitation dominates in the summer and in the southern part of the domain due to greater tropospheric instability in warmer periods. Non-convective precipitation becomes more significant during the spring, but it contributes much less in total rain. Both WRF and WRF/Chem models overpredict the mean total daily precipitation, with a positive bias that increases as the convective precipitation increases in warmer months. This appears to be a common problem with the prediction of convective precipitation; it is associated with its high spatial variability. The comparison of WRF/Chem results with those of WRF shows that a non-negligible change in both convective and cloud-resolved (non-convective) precipitation is caused by chemistry (including aerosols) over most parts of the domain. These changes can be attributed to both radiative and microphysical causes. A chemistry-induced change of approximately 15% is found in the five-month mean daily convective precipitation over areas with high convective rain. This can be traced to radiative effects that cause additional surface cooling when chemistry is included. This surface cooling occurs predominantly in regions of high column-integrated PM2.5, due to a combination of direct light scattering by the aerosols and by clouds nucleated by the aerosols. Although, total non-convective rain is less than total convective rain in the domain, chemistry-induced effects on the former are more pronounced than those on the latter. While the effects of chemistry on non-convective rain have significant spatial variability, the inclusion of chemistry causes a small, but widespread increase in non-convective rain in the sparsely populated southern part of the domain and a pronounced increase near the heavily populated urban areas in the northeastern U.S. coast. A chemistry-induced increase of about +30% is evident in the five-month mean daily non-convective precipitation over the heavily urbanized parts of the Atlantic coast.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  16. A kinetic energy study of the meso beta-scale storm environment during AVE-SESAME 5 (20-21 May 1979)

    NASA Technical Reports Server (NTRS)

    Printy, M. F.; Fuelberg, H. E.

    1984-01-01

    Kinetic energy of the near storm environment was analyzed by meso beta scale data. It was found that horizontal winds in the 400 to 150 mb layer strengthen rapidly north of the developing convection. Peak values then decrease such that the maximum disappears 6 h later. Southeast of the storms, wind speeds above 300 mb decrease nearly 50% during the 3 h period of most intense thunderstorm activity. When the convection dissipates, wind patterns return to prestorm conditions. The mesoscale storm environment of AVE-SESAME 5 is characterized by large values of cross contour generation of kinetic energy, transfers of energy to nonresolvable scales of motion, and horizontal flux divergence. These processes are maximized within the upper troposphere and are greatest during times of strongest convection. It is shown that patterns agree with observed weather features. The southeast area of the network is examined to determine causes for vertical wind variations.

  17. Chemical Physics Summer School

    SciTech Connect

    2002-06-28

    The Gordon Research Conference (GRC) on Chemical Physics Summer School was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  18. Summer Success Story.

    ERIC Educational Resources Information Center

    Matika, Francis W.

    1994-01-01

    Pennsylvania's Beaver Valley Intermediate Unit built a collaborative 2-week summer academy, opening it to students in the other 14 school districts in the county. Cooperation among all the districts provided students opportunities for expanded learning experiences. (MLF)

  19. Cashing In on Summer.

    ERIC Educational Resources Information Center

    Instructor, 1980

    1980-01-01

    Suggests ways teachers can use their talents and expertise to create jobs for themselves that supply extra income during the summer. These "moonlighting" ideas include tutoring, giving guided tours, planning weddings, and starting exercise classes. (SJL)

  20. The Purdue Summer Internship

    ERIC Educational Resources Information Center

    Hamilton, William; And Others

    1976-01-01

    Describes a program in which college agricultural education majors between their junior and senior years are placed with vocational agriculture teachers to gain experience in conducting a summer vocational agriculture program. (HD)

  1. A Summer Camp Assessment.

    ERIC Educational Resources Information Center

    Pratte, Janice L.; DiNardi, Salvatore R.

    1979-01-01

    Reported are the results of a project assessing the impact of a revised Massachusetts sanitary code on 500 summer camps for children. The study compared camp compliances with the proposed regulations to the level of compliance with existing regulations. (BT)

  2. Mesoscale and Synoptic Scale Interactions Leading to Intense Convection: The Case of 18 August 2008

    NASA Astrophysics Data System (ADS)

    Oprea, C.; Paraschivescu, M.

    2009-04-01

    A case study is presented involving a supercell storm that produced large hail and high rainfall rate damage in the hilly region of the southern Romania during the 18 August 2008. The study emphasizes the pre convective period and examines interactions between mesoscale processes and the synoptic scale environment that led to thunderstorm development. The suppercell storms formed after a quasi-stationary mesoscale convective system has affected central and southern part of Romania including the study area, making the thunderstorm difficult to forecast. Mesoscale analysis using real and model dates revealed the initiations of the convection in the area of interaction of two convergence lines. One was created by the interaction of the synoptic flow with the curved shape of the Carpathian Mountains, and second was mountain breeze. This work, along with similar studies, illustrates the wide range of factors that must be considered for thunderstorm forecast decision in Romanian territory.

  3. National Severe Storms Forecast Center

    NASA Technical Reports Server (NTRS)

    1977-01-01

    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.

  4. Assessing the Predictability of Convection using Ensemble Data Assimilation of Simulated Radar Observations in an LETKF system

    NASA Astrophysics Data System (ADS)

    Lange, Heiner; Craig, George

    2014-05-01

    This study uses the Local Ensemble Transform Kalman Filter (LETKF) to perform storm-scale Data Assimilation of simulated Doppler radar observations into the non-hydrostatic, convection-permitting COSMO model. In perfect model experiments (OSSEs), it is investigated how the limited predictability of convective storms affects precipitation forecasts. The study compares a fine analysis scheme with small RMS errors to a coarse scheme that allows for errors in position, shape and occurrence of storms in the ensemble. The coarse scheme uses superobservations, a coarser grid for analysis weights, a larger localization radius and larger observation error that allow a broadening of the Gaussian error statistics. Three hour forecasts of convective systems (with typical lifetimes exceeding 6 hours) from the detailed analyses of the fine scheme are found to be advantageous to those of the coarse scheme during the first 1-2 hours, with respect to the predicted storm positions. After 3 hours in the convective regime used here, the forecast quality of the two schemes appears indiscernible, judging by RMSE and verification methods for rain-fields and objects. It is concluded that, for operational assimilation systems, the analysis scheme might not necessarily need to be detailed to the grid scale of the model. Depending on the forecast lead time, and on the presence of orographic or synoptic forcing that enhance the predictability of storm occurrences, analyses from a coarser scheme might suffice.

  5. The influence of topography on vertical velocity of air in relation to severe storms near the Southern Andes Mountains

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    On the basis of 180 storms which took place between 2004 and 2011 over the province of Mendoza (Argentina) near to the Andes Range at southern mid-latitudes, we consider those registered in the northern and central crop areas (oases). The regions affected by these storms are currently protected by an operational hail mitigation project. Differences with previously reported storms detected in the southern oasis are highlighted. Mendoza is a semiarid region situated roughly between 32S and 37S at the east of the highest Andes top. It forms a natural laboratory where different sources of gravity waves, mainly mountain waves, occur. In this work, we analyze the effects of flow over topography generating mountain waves and favoring deep convection. The joint occurrence of storms with hail production and mountain waves is determined from mesoscale numerical simulations, radar and radiosounding data. In particular, two case studies that properly represent diverse structures observed in the region are considered in detail. A continuous wavelet transform is applied to each variable and profile to detect the main oscillation modes present. Simulated temperature profiles are validated and compared with radiosounding data. Each first radar echo, time and location are determined. The necessary energy to lift a parcel to its level of free convection is tested from the Convective Available Potential Energy and Convection Inhibition. This last parameter is compared against the mountain waves' vertical kinetic energy. The time evolution and vertical structure of vertical velocity and equivalent potential temperature suggest in both cases that the detected mountain wave amplitudes are able to provide the necessary energy to lift the air parcel and trigger convection. A simple conceptual scheme linking the dynamical factors taking place before and during storm development is proposed.

  6. Research on Historical Records of Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Lakhina, G. S.; Alex, S.; Tsurutani, B. T.; Gonzalez, W. D.

    In recent times, there has been keen interest in understanding Sun-Earth connection events, such as solar flares, CMEs and concomitant magnetic storms. Magnetic storms are the most dramatic and perhaps important component of space weather effects on Earth. Super-intense magnetic storms (defined here as those with Dst < -500 nT, where Dst stands for the disturbance storm time index that measures the strength of the magnetic storm) although relatively rare, have the largest societal and technological relevance. Such storms can cause life-threatening power outages, satellite damage, communication failures and navigational problems. However, the data for such magnetic storms is rather scarce. For example, only one super-intense magnetic storm has been recorded (Dst=-640 nT, March 13, 1989) during the space-age (since 1958), although such storms may have occurred many times in the last 160 years or so when the regular observatory network came into existence. Thus, research on historical geomagnetic storms can help to create a good data base for intense and super-intense magnetic storms. From the application of knowledge of interplanetary and solar causes of storms gained from the spaceage observations applied to the super-intense storm of September 1-2, 1859, it has been possible to deduce that an exceptionally fast (and intense) magnetic cloud was the interplanetary cause of this geomagnetic storm with a Dst -1760 nT, nearly 3 times as large as that of March 13, 1989 super-intense storm. The talk will focus on super-intense storms of September 1-2, 1859, and also discuss the results in the context of some recent intense storms.

  7. Storm type effects on super Clausius-Clapeyron scaling of intense rainstorm properties with air temperature

    NASA Astrophysics Data System (ADS)

    Molnar, P.; Fatichi, S.; Gaál, L.; Szolgay, J.; Burlando, P.

    2015-04-01

    Extreme precipitation is thought to increase with warming at rates similar to or greater than the water vapour holding capacity of the air at ~ 7% °C-1, the so-called Clausius-Clapeyron (CC) rate. We present an empirical study of the variability in the rates of increase in precipitation intensity with air temperature using 30 years of 10 min and 1 h data from 59 stations in Switzerland. The analysis is conducted on storm events rather than fixed interval data, and divided into storm type subsets based on the presence of lightning which is expected to indicate convection. The average rates of increase in extremes (95th percentile) of mean event intensity computed from 10 min data are 6.5% °C-1 (no-lightning events), 8.9% °C-1 (lightning events) and 10.7% °C-1 (all events combined). For peak 10 min intensities during an event the rates are 6.9% °C-1 (no-lightning events), 9.3% °C-1 (lightning events) and 13.0% °C-1 (all events combined). Mixing of the two storm types exaggerates the relations to air temperature. Doubled CC rates reported by other studies are an exception in our data set, even in convective rain. The large spatial variability in scaling rates across Switzerland suggests that both local (orographic) and regional effects limit moisture supply and availability in Alpine environments, especially in mountain valleys. The estimated number of convective events has increased across Switzerland in the last 30 years, with 30% of the stations showing statistically significant changes. The changes in intense convective storms with higher temperatures may be relevant for hydrological risk connected with those events in the future.

  8. A summary of research on mesoscale energetics of severe storm environments

    NASA Technical Reports Server (NTRS)

    Fuelberg, H. E.

    1985-01-01

    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.

  9. Global lightning and severe storm monitoring from GPS orbit

    SciTech Connect

    Suszcynsky, D. M.; Jacobson, A. R.; Linford, J; Pongratz, M. B.; Light, T.; Shao, X.

    2004-01-01

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

  10. An assessment of the potential of earth observation data to detect and monitor storm cells associated with natural hazards - an application to an extreme weather event in southeastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Mavrakou, T.; Cartalis, C.

    2015-04-01

    Storm cells that evolve in Mesoscale Convective Systems (MCSs) can be recognised with the use of satellite images. In this study, Meteosat images are used for the early detection and monitoring of the evolution of storm cells associated with MCSs. The developed methodology is based on the estimation of the "Airmass" and "Convective storm" composites, at fifteen minutes intervals. The methodology was applied on a selected four-day case study in February 2013, when a depression was developed over Africa and moved across the Mediterranean resulting in deep convection along its trajectory and in an extreme weather event (heavy rainfall associated with severe flooding) at the wider urban agglomeration of Athens. The produced composites detect potential vorticity (PV) anomaly related to cyclogenesis and increase the potential to detect and monitor storm cells associated with natural hazards.

  11. Supergranulation, a convective phenomenon

    NASA Astrophysics Data System (ADS)

    Udayashankar, Paniveni

    2015-08-01

    Observation of the Solar photosphere through high resolution instruments have long indicated that the surface of the Sun is not a tranquil, featureless surface but is beset with a granular appearance. These cellular velocity patterns are a visible manifestation of sub- photospheric convection currents which contribute substantially to the outward transport of energy from the deeper layers, thus maintaining the energy balance of the Sun as a whole.Convection is the chief mode of transport in the outer layers of all cool stars such as the Sun (Noyes,1982). Convection zone of thickness 30% of the Solar radius lies in the sub-photospheric layers of the Sun. Convection is revealed on four scales. On the scale of 1000 km, it is granulation and on the scale of 8-10 arcsec, it is Mesogranulation. The next hierarchial scale of convection ,Supergranules are in the range of 30-40 arcsec. The largest reported manifestation of convection in the Sun are ‘Giant Cells’or ‘Giant Granules’, on a typical length scale of about 108 m.'Supergranules' is caused by the turbulence that extends deep into the convection zone. They have a typical lifetime of about 20hr with spicules marking their boundaries. Gas rises in the centre of the supergranules and then spreads out towards the boundary and descends.Broadly speaking supergranules are characterized by the three parameters namely the length L, the lifetime T and the horizontal flow velocity vh . The interrelationships amongst these parameters can shed light on the underlying convective processes and are in agreement with the Kolmogorov theory of turbulence as applied to large scale solar convection (Krishan et al .2002 ; Paniveni et. al. 2004, 2005, 2010).References:1) Noyes, R.W., The Sun, Our Star (Harvard University Press, 1982)2) Krishan, V., Paniveni U., Singh , J., Srikanth R., 2002, MNRAS, 334/1,2303) Paniveni , U., Krishan, V., Singh, J., Srikanth, R., 2004, MNRAS, 347, 1279-12814) Paniveni , U., Krishan, V., Singh, J., Srikanth, R., 2005, Solar Physics, 231, 1-105) Paniveni , U., Krishan, V., Singh, J., Srikanth, R., 2010, MNRAS, 402, Issue 1, 424-428

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  13. Multi-Sensor Analysis of Overshooting Tops in Tornadic Storms

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  14. Anomalously weak solar convection.

    PubMed

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

    2012-07-24

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

  15. Anomalously Weak Solar Convection

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  16. Convection in planetary magnetospheres

    NASA Astrophysics Data System (ADS)

    Hill, T. W.

    Magnetospheric convection is a system of bulk motion of magnetospheric flux tubes, powered either internally by an unstable distribution of plasma produced therein, or externally by coupling to the motion of an adjacent medium. Internally powered convection results from one of three types of magnetospheric interchange instability: the flute instability associated with a plasma pressure distribution containing excess internal energy of compression; the Rayleigh-Taylor instability deriving from a plasma mass distribution containing excess gravitational potential energy; and the centrifugal instability which is the inverse of the Rayleigh-Taylor instability, occurring outside the synchronous orbit radius. The centrifugal instability is primarily responsible for convection in the magnetosphere of Jupiter, and probably also that of Saturn. Externally powered convection may be driven either by atmospheric winds, coupled to the magnetosphere by ionospheric Pedersen currents, or by the solar wind, coupled to the magnetosphere by one or more collisionless momentum transfer processes. The solar wind is the primary driver of convection in earth's magnetosphere, and the primary coupling mechanism is interconnection between the geomagnetic and interplanetary magnetic fields. For the magnetosphere of Uranus (if it exists), a disc dynamo interaction has been proposed that is powered by a direct coupling between thg flow of the solar wind and the rotation of the planet.

  17. Convection in containerless processing.

    PubMed

    Hyers, Robert W; Matson, Douglas M; Kelton, Kenneth F; Rogers, Jan R

    2004-11-01

    Different containerless processing techniques have different strengths and weaknesses. Applying more than one technique allows various parts of a problem to be solved separately. For two research projects, one on phase selection in steels and the other on nucleation and growth of quasicrystals, a combination of experiments using electrostatic levitation (ESL) and electromagnetic levitation (EML) is appropriate. In both experiments, convection is an important variable. The convective conditions achievable with each method are compared for two very different materials: a low-viscosity, high-temperature stainless steel, and a high-viscosity, low-temperature quasicrystal-forming alloy. It is clear that the techniques are complementary when convection is a parameter to be explored in the experiments. For a number of reasons, including the sample size, temperature, and reactivity, direct measurement of the convective velocity is not feasible. Therefore, we must rely on computation techniques to estimate convection in these experiments. These models are an essential part of almost any microgravity investigation. The methods employed and results obtained for the projects levitation observation of dendrite evolution in steel ternary alloy rapid solidification (LODESTARS) and quasicrystalline undercooled alloys for space investigation (QUASI) are explained. PMID:15644376

  18. Convective quasi-equilibrium

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  20. NPDES storm-water-sampling guidance document

    SciTech Connect

    Not Available

    1992-07-01

    The manual provides operators of facilities that discharge storm water associated with industrial activity and operators of large and medium municipal separate storm sewer systems with guidance on storm water sampling. The manual is primarily designed to assist operators/owners in planning for and fulfilling the National Pollutant Discharge Elimination System (NPDES) storm water discharge sampling requirements for permit applications as well as for other storm water sampling needs. The manual summarizes the storm water application regulations and gives instructions on filling out Form 2-F. The document describes 'representative' storms and problems with obtaining data from storm events. An in-depth discussion of collecting grab and composite sampling, both manually and by automatic sampler is provided. Sampling protocol modifications, requirements for petitions for substituting substantially identical effluents, and requests for approval of alternate test procedures are discussed. Safety issues are introduced.

  1. Diurnal low-level wind oscillation and storm-relative helicity

    NASA Astrophysics Data System (ADS)

    Maddox, Robert A.

    Thunderstorms characterized by significant mesocyclones occur within local environments that exhibit strong, stormrelative low-level winds which veer substantially with height [e.g., Weisman and Klemp, 1984, Burgess and Curran, 1985; Davies-Jones et al., 1990]. Such an environment, i.e., one with high storm-relative helicity [Lilly, 1983, 1986; Davies-Jones, 1984; Brooks et al, this volume; Davies-Jones, 1991], is favorable for the occurrence of intense tornadoes when and if deep moist convection occurs. All atmospheric processes that act to modify the character of the low-level, vertical wind profile can lead to enhanced or diminished storm-relative helicity and thereby affect the structure and character of thunderstorms, should they occur. Since changes in storm motion also affect relative helicity, it is assumed for simplicity that changes in the lower troposphere winds have little affect upon the movement of thunderstorms.

  2. Auroral Zone E-Region Electron Density Geomagnetic Storm Enhancements Predicted by the Empirical STORM-E Model

    NASA Astrophysics Data System (ADS)

    Mertens, Christopher; Bilitza, Dieter; Xu, Xiaojing

    2012-07-01

    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 electron densities. The empirical model is called STORM-E. 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 um channel limb radiance measurements. The storm-time response of the NO+(v) 4.3 um VER is most sensitive to auroral particle precipitation. A statistical database of storm-time to climatological quiet-time ratios of SABER-observed NO+(v) 4.3 um 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. In this paper, the development of the E-region electron density storm-time correction factor is described. The STORM-E storm-time correction factor is fit to a single geomagnetic index. There are four versions of the STORM-E model. Each version is fit to one of the following indices: HP-, AE-, Ap-, or Dst. High-latitude incoherent scatter radar (ISR) E-region electron density measurements are compared to STORM-E predictions for various geomagnetic storm periods during solar cycle 23. These comparisons show that STORM-E significantly improves the prediction of E-region electron density enhancements due to auroral particle precipitation, in comparison to the nominal International Reference Ionosphere (IRI) model or to the quiet-time baseline electron density concentrations measured by ISR. The version of the STORM-E model based on the fit to the Ap-index is now incorporated into the 2012 release of the IRI.

  3. Cement Creek Following Storm Event

    Cement Creek following storm event in July, 2004. Note the orange discoloration of the stream derived from weathering of bedrocks and from mined areas. This type of event happens frequently in the Animas Watershed near Silverton, Colorado. View is to the south, with Kendall Mountain in the distance....

  4. Rain from Tropical Storm Noel

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Though not the most powerful storm of the 2007 Atlantic Hurricane season, Tropical Storm Noel was among the most deadly. Only Category 5 Hurricane Felix and its associated flooding had a higher toll. The slow-moving Tropical Storm Noel inundated the Dominican Republic, Haiti, Jamaica, Cuba, and the Bahamas with heavy rain between October 28 and November 1, 2007. The resulting floods and mudslides left at least 115 dead and thousands homeless throughout the Caribbean, reported the Associated Press on November 2, 2007. This image shows the distribution of the rainfall that made Noel a deadly storm. The image shows rainfall totals as measured by the Multi-satellite Precipitation Analysis (MPA) at NASA Goddard Space Flight Center from October 26 through November 1, 2007. The analysis is based on measurements taken by the Tropical Rainfall Measuring Mission (TRMM) satellite. The heaviest rainfall fell in the Dominican Republic and the Bahamas, northeast of Noel's center. Areas of dark red show that rainfall totals over the south-central Dominican Republic and parts of the Bahamas were over 551 millimeters (21 inches). Much of eastern Hispaniola, including both the Dominican Republic and Haiti received at least 200 mm (about 8 inches) of rain, shown in yellow. Rainfall totals over Haiti and Cuba were less, with a range of at least 50 mm (2 inches) to over 200 mm (8 inches).

  5. Managing storm water at airports

    SciTech Connect

    Halm, M.J.

    1996-09-01

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

  6. ENSO and winter storms in California

    USGS Publications Warehouse

    Cayan, D.R.; Bromirski, Peter

    2003-01-01

    The frequency and intensity of North Pacific winter storms that penetrate the California coast drives the winds, sea level, precipitation and streamflow that are crucial influences on coastal processes. There is considerable variability of these storm characteristics, in large part owing to the El Nino/Southern Oscillation (ENSO} phenomenon. There is a great contrast of the storm characteristics during the El Nino phase vs. the La Nina phase, with the largest scale, southerly extensive winter storms generated during El Nino.

  7. Effects of urban pollution on downwind storms: An energetic perspective

    NASA Astrophysics Data System (ADS)

    Carrio, G. G.

    2011-12-01

    In two previous studies. the effects of the Houston Metropolitan area on the characteristics and intensity of convection and precipitation were investigated for events triggered by the sea-breeze circulation . Carrió et al (2010) isolated the effects of the land-use change and examined the indirect effects of urban pollution considering sources of varied intensity linked to sub-grid urban area fractions. The Regional Atmospheric Modeling System developed at Colorado State University (RAMS@CSU) was validated against radar observations for the case used as a benchmark for these sensitivity experiments. With regard to the aerosol effects, as other authors have also found, enhancing cloud condensation nuclei (CCN) can produce an invigoration of downwind convective cells due to additional latent heat release. However, results showed an interesting non-monotonic behavior of convection intensity and precipitation when more intense CCN surface sources were considered. A second study (Carrió et al, 2011) consisted of a large number of multi-grid simulations (more than one hundred) and varied convective instability in addition to the intensity of urban pollution sources. The non-monotonic response was linked to the riming efficiency reduction of ice particles when aerosol concentrations are greatly enhanced. Therefore, a greater fraction of the ice-phase condensed water mass is transported out of the storm as pristine ice crystals instead of being transferred to precipitating water species. Even though, Carrió et al, (2011) strongly supports the relationship between the behavior of the simulated precipitation and the aforementioned microphysical mechanism, the evidence could be considered somewhat "circumstantial". For that reason, the problem was revisited with a new modeling study that approaches it from a more energetic perspective. These new numerical experiments used RAMS@CSU coupled to the Town Energy Budget (TEB) urban model and a microphysical module that considers the explicit activation of CCN (and giant CCN), a bimodal representation of cloud droplets, and a bin-emulation approach for droplet collection, ice-particle riming, and sedimentation. Model outputs every 30s were used to analyze the (indirect) effects of urban pollution on the efficiency of microphysical processes leading to the generation of precipitation particles (involving ice-phase and warm rain), latent heat release rates, buoyancy, vertical momentum, as well as several integral quantities linked to the convective cells simulated downwind of the urban complex. Results clearly support the explanations inferred in the previous study, show a non-monotony behavior of several macroscopic characteristics of the downwind convective cells, and indicate that the expected increase of the particulate pollution is more likely to selectively enhance precipitation of convective events characterized by higher instability and extreme precipitation events.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  9. HF radar observations of the F region ionospheric plasma response to Storm Sudden Commencements

    NASA Astrophysics Data System (ADS)

    Kane, T. A.; Makarevich, R. A.

    2010-07-01

    Performance of the Super Dual Auroral Radar Network (SuperDARN) HF radars during geomagnetic storms is investigated by analyzing the data collected during storm events over a 5-year period. Changes in the occurrence of F region HF backscatter observed by the 6 most equatorward radars are analyzed statistically using a superposed epoch analysis method with respect to a Storm Sudden Commencement (SSC). Regular diurnal variations of the echo occurrence during geomagnetically quiet days are produced and the amount of detected backscatter during storms is adjusted using quiet time curves. All radars considered in this study show a significant decrease in the number of detected echoes approximately 24 hours following SSC. Unexpected significant changes in occurrence levels are also present within a few hours of SSC, with most radars observing an increase in the amount of backscatter detected. The typical time evolution of F region echo occurrence is highly reminiscent of that of the electron density reported previously. Also considered is the ionospheric convection response to SSC observed by the zonally looking SuperDARN Unwin radar in New Zealand. It is shown that the initial response to SSC is instantaneous within uncertainty and appears to be independent of the magnetic latitude and local time. The observed convection response timing and morphology are discussed in the context of possible ionospheric propagation mechanisms.

  10. Numerical simulation of the effects of cooling tower complexes on clouds and severe storms

    NASA Astrophysics Data System (ADS)

    Orville, Harold D.; Eckhoff, Peter A.; Peak, James E.; Hirsch, John H.; Kopp, Fred J.

    A two-dimensional, time-dependent model has been developed which gives realistic simulations of many severe storm processes—such as heavy rains, hail and strong winds. The model is a set of partial differential equations describing time changes of momentum, energy, and mass (air and various water substances such as water vapor, cloud liquid, cloud ice, rainwater and hail). In addition, appropriate boundary and initial conditions (taken from weather sounding data) are imposed on a domain approx. 20 km high by 20 km wide with 200 m grid intervals to complete the model. Modifications have been made to the model which allow additional water vapor and heat to be added at several lower grid points, simulating effluents from a power park. Cases have been run which depict realistic severe storm situations. One atmospheric sounding has a strong middle-level inversion which tends to inhibit the first convective clouds but gives rise later to a severe storm with hail and heavy rains. One other sounding, is taken from a day in which a severe storm occurred in the Miami area. A third sounding depicts atmospheric conditions in which severe storms formed in the vicinity of Huron, South Dakota. The results indicate that a power park emitting 80 % latent heat and 20 % sensible heat has little effect on the simulated storm. A case with 100 % sensible heat emission leads to a much different solution, with the simulated storm reduced in severity and the rain and hail redistributed. A case in which water vapor is accumulated in a region and released over a broad depth results in slightly more rain from a severe storm.

  11. Lightning characteristics of derecho producing mesoscale convective systems

    NASA Astrophysics Data System (ADS)

    Bentley, Mace L.; Franks, John R.; Suranovic, Katelyn R.; Barbachem, Brent; Cannon, Declan; Cooper, Stonie R.

    2015-11-01

    Derechos, or widespread, convectively induced wind storms, are a common warm season phenomenon in the Central and Eastern United States. These damaging and severe weather events are known to sweep quickly across large spatial regions of more than 400 km and produce wind speeds exceeding 121 km h-1. Although extensive research concerning derechos and their parent mesoscale convective systems already exists, there have been few investigations of the spatial and temporal distribution of associated cloud-to-ground lightning with these events. This study analyzes twenty warm season (May through August) derecho events between 2003 and 2013 in an effort to discern their lightning characteristics. Data used in the study included cloud-to-ground flash data derived from the National Lightning Detection Network, WSR-88D imagery from the University Corporation for Atmospheric Research, and damaging wind report data obtained from the Storm Prediction Center. A spatial and temporal analysis was conducted by incorporating these data into a geographic information system to determine the distribution and lightning characteristics of the environments of derecho producing mesoscale convective systems. Primary foci of this research include: (1) finding the approximate size of the lightning activity region for individual and combined event(s); (2) determining the intensity of each event by examining the density and polarity of lightning flashes; (3) locating areas of highest lightning flash density; and (4) to provide a lightning spatial analysis that outlines the temporal and spatial distribution of flash activity for particularly strong derecho producing thunderstorm episodes.

  12. Vertical structure of Saturn lightning storms and storm-related dark ovals

    NASA Astrophysics Data System (ADS)

    Sromovsky, Lawrence A.; Baines, Kevin H.; Fry, Patrick M.

    2014-11-01

    In Cassini ISS images of Saturn during 2004-2006 Dyudina et al. (2007, Icarus 190, 545-555) identified four cases in which bright cloud features near 35o S were correlated with thunderstorm activity, inferred from SED events detected by the Radio and Plasma Wave Science instrument. The bright features left behind remnant dark ovals that reached full contrast within about a week. Baines et al. (2009, Plan. & Space Sci. 57, 1650-1658) investigated similar radio-correlated storms, using 2008 VIMS spectra. Noting that the dark ovals were about 20% less reflective than surrounding clouds over a wide spectral range, they suggested that the cloud particles might contain a broadband absorber that was produced by lightning-induced chemistry at the 10-20 bar water cloud level and convected up to the visible cloud level. Another possibility is that lower optical depths cause the ovals to be less reflective than the surrounding clouds. We carried out quantitative radiative transfer calculations to evaluate these alternatives, and also derived cloud models for the active region that is the presumed source of lightning. The main result for the dark ovals is that we can obtain good fits with typical condensates in vertically thin cloud layers, but can also obtain good fits with deep clouds of composite particles containing a sooty core within a shell of n=1.4+0i material. However, unlike Saturn's Great Storm of 2010-2011 (Sromovsky et al. 2013, Icarus), neither the bright clouds nor the dark ovals show the significant 3-micron absorption that would be expected if NH3, NH4SH, or H20 were lofted to upper cloud level. This missing absorption tends to favor models in which the upper cloud layer (near 250 mbar) is comprised of conservative (non-absorbing) particles and physically thin, in which case the dark oval spectra can be explained by a reduced upper cloud opacity (by ~50%) relative to surrounding clouds, and raises the possibility that the upper cloud features might be generated by waves rather than by convection all the way up to the visible cloud level.This research was supported by grant NNX11AM58G from NASA's Outer Planets Research Program.

  13. Active control of convection

    SciTech Connect

    Bau, H.H.

    1995-12-31

    Using stability theory, numerical simulations, and in some instances experiments, it is demonstrated that the critical Rayleigh number for the bifurcation (1) from the no-motion (conduction) state to the motion state and (2) from time-independent convection to time-dependent, oscillatory convection in the thermal convection loop and Rayleigh-Benard problems can be significantly increased or decreased. This is accomplished through the use of a feedback controller effectuating small perturbations in the boundary data. The controller consists of sensors which detect deviations in the fluid`s temperature from the motionless, conductive values and then direct actuators to respond to these deviations in such a way as to suppress the naturally occurring flow instabilities. Actuators which modify the boundary`s temperature/heat flux are considered. The feedback controller can also be used to control flow patterns and generate complex dynamic behavior at relatively low Rayleigh numbers.

  14. Impact of anthropogenic aerosols on Indian summer monsoon

    SciTech Connect

    Wang, Chien; Kim, Dongchul; Ekman, Annica; Barth, Mary; Rasch, Philip J.

    2009-11-05

    Using an interactive aerosol-climate model we find that absorbing anthropogenic aerosols, whether coexisting with scattering aerosols or not, can significantly affect the Indian summer monsoon system. We also show that the influence is reflected in a perturbation to the moist static energy in the sub-cloud layer, initiated as a heating by absorbing aerosols to the planetary boundary layer. The perturbation appears mostly over land, extending from just north of the Arabian Sea to northern India along the southern slope of the Tibetan Plateau. As a result, during the summer monsoon season, modeled convective precipitation experiences a clear northward shift, coincidently in agreement with observed monsoon precipitation changes in recent decades particularly during the onset season. We demonstrate that the sub-cloud layer moist static energy is a useful quantity for determining the impact of aerosols on the northward extent and to a certain degree the strength of monsoon convection.

  15. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

  16. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

  17. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

  18. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

  19. 46 CFR 169.329 - Storm rails.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Storm rails. 169.329 Section 169.329 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Construction and Arrangement Rails and Guards § 169.329 Storm rails. Suitable storm rails or hand grabs must...

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

    NASA Astrophysics Data System (ADS)

    Grant, Leah Danielle

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

  1. Interactive modeling of storm impact

    NASA Astrophysics Data System (ADS)

    van Rooijen, A.; Baart, F.; Roelvink, J. A.; Donchyts, G.; Scheel, F.; de Boer, W.

    2014-12-01

    In the past decades the impact of storms on the coastal zone has increasingly drawn the attention of policy makers and coastal planners, engineers and researchers. The mean reason for this interest is the high density of the world's population living near the ocean, in combination with climate change. Due to sea level rise and extremer weather conditions, many of the world's coastlines are becoming more vulnerable to the potential of flooding. Currently it is common practice to predict storm impact using physics-based numerical models. The numerical model utilizes several inputs (e.g. bathymetry, waves, surge) to calculate the impact on the coastline. Traditionally, the numerical modeller takes the following three steps: schematization/model setup, running and post-processing. This process generally has a total feedback time in the order of hours to days, and is suitable for so-called confirmatory modelling.However, often models are applied as an exploratory tool, in which the effect of e.g. different hydraulic conditions, or measures is investigated. The above described traditional work flow is not the most efficient method for exploratory modelling. Interactive modelling lets users adjust a simulation while running. For models typically used for storm impact studies (e.g. XBeach, Delft3D, D-Flow FM), the user can for instance change the storm surge level, wave conditions, or add a measure such as a nourishment or a seawall. The model will take the adjustments into account immediately, and will directly compute the effect. Using this method, tools can be developed in which stakeholders (e.g. coastal planners, policy makers) are in control and together evaluate ideas by interacting with the model. Here we will show initial results for interactive modelling with a storm impact model.

  2. Physics of Stellar Convection

    NASA Astrophysics Data System (ADS)

    Arnett, W. David

    2009-05-01

    We review recent progress using numerical simulations as a testbed for development of a theory of stellar convection, much as envisaged by John von Newmann. Necessary features of the theory, non-locality and fluctuations, are illustrated by computer movies. It is found that the common approximation of convection as a diffusive process presents the wrong physical picture, and improvements are suggested. New observational results discussed at the conference are gratifying in their validation of some of our theoretical ideas, especially the idea that SNIb and SNIc events are related to the explosion of massive star cores which have been stripped by mass loss and binary interactions [1

  3. Convection in protoneutron stars.

    NASA Astrophysics Data System (ADS)

    Keil, W.; Janka, H.-T.; Müller, E.

    Convectively enhanced neutrino (ν) luminosities from the protoneutron star (PNS) can provide an essential condition for a Type-II supernova explosion. Very recent two-dimensional, self-consistent, general relativistic simulations of the cooling of a newly-formed neutron star demonstrate and confirm the possibility that quasi-Ledoux convection, driven by negative lepton number and entropy gradients, may encompass the whole PNS within less than 1 s and can lead to an increase of the neutrino fluxes by up to a factor of two.

  4. Winds, Condensation Clouds, Dust Storms, and Polar Caps of Mars

    NASA Astrophysics Data System (ADS)

    Ingersoll, A. P.

    2001-05-01

    Using the wide angle images from the Mars Orbiter Camera (MOC), we have constructed daily global maps in color (from the red and violet filters) at 7 km per pixel resolution. The maps have been made into movies that show dust storms and condensate clouds as well as the positions of the seasonal polar caps. From the dust and condensate clouds, we can measure winds and can monitor the climatology of these features. We can measure the spreading rate of the dust storms, and we can observe the relation between dust storms and the polar caps. Using the narrow angle images from the MOC, we have monitored features within the South Polar residual cap -- the so-called Swiss cheese features. These are circular depressions tens of meters deep and hundreds of meters in diameter that are only found in the south and only where the frost remains throughout the summer. The obvious inference is that they form spontaneously in carbon dioxide ice. A key question is whether the South Polar residual cap is made entirely of carbon dioxide, or whether it could be a veneer of carbon dioxide over a much thicker mass of water ice. The circular depressions may provide the answer. Preliminary modeling of depressions in pure carbon dioxide frost suggests that the frost heals itself and the depressions disappear. Putting water ice underneath the carbon dioxide leads to a long lived depression that grows slowly outward and resembles those observed.

  5. Thermospheric composition changes seen during a geomagnetic storm

    NASA Technical Reports Server (NTRS)

    Burns, A. G.; Kileen, T. L.; Roble, R. G.

    1992-01-01

    The largest magnitude winds observed using the instruments on board the Dynamics Explorer 2 (DE-2) satellite were measured during the large geomagnetic storm that occurred on November 24, 1982. Neutral temperatures exceeded 2000 K during this storm, and these high temperatures, combined with the very large observed winds and the very full instrumental coverage available in both hemispheres, make it a unique event to study. This paper presents results obtained using these DE-2 data and a time dependent simulation of the event made using the NCAR Thermosphere/Ionosphere General Circulation Model (NCAR-TIGCM). In general, the agreement between model calculations and the data is very good, implying that most of the important physical processes controlling the energetics and dynamics of the thermosphere are reasonably well represented in the model. The modeled summer hemisphere changes in the mass mixing ratio of N2 (Psi(N2)) are in very good agreement with the averaged data in both hemispheres. This paper describes model-experiment comparisons for the November 24, 1982 geomagnetic storm changes.

  6. Insights into mid-latitude storm track dynamics from simulations with an idealized dry GCM

    NASA Astrophysics Data System (ADS)

    Mbengue, C. O.; Schneider, T.

    2012-12-01

    The mid-latitude storm tracks play an important role in balancing the earth's heat and momentum budget. They have a significant human impact through precipitation and adverse weather conditions; thus, the storm track response to changing climatic conditions is of great interest. In this study, we investigate the climatological response of the mid-latitude storm tracks to varying mean global temperature and convective static stability, using an idealized dry GCM. We demonstrate storm track migration in response to changes in global-mean surface temperatures without modifying the surface pole-equator temperature contrast or including moisture-related effects. The results help interpret the findings of previous global warming studies in which the mid-latitude storm tracks migrate poleward with increasing mean global temperatures. In our study, the storm track position is found to be particularly sensitive to changes in tropical static stability and tropopause height and their effect on the Hadley circulation. The mechanisms driving the dynamics of the mid-latitude storm tracks have been elusive. However, making use of the simplified framework employed in this study, which lends itself to dynamical decompositions, we have been able to improve upon some existing theories on storm track dynamics in dry atmospheres, as well as make additional observations. Previous studies into dry atmospheric dynamics have shown a linear scaling between eddy kinetic energy, a robust measure of the level of storminess, and the mean available potential energy (MAPE). This scaling is utilized in a decomposition that shows that the dominant quantity in storm track dynamics is the meridional gradient of the potential temperature—a measure of baroclinicity. This observation leads us to look for dynamical mechanisms that, on average, dictate the location of regions of elevated baroclinicity. Some credible explanations include the effects on mid-latitude isentropic slopes through a raising or lowering of the tropical tropopause, and effects of a migrating terminus of the Hadley cell. In a simulation where we only vary the convective lapse rate, the decomposition reinforces the meridional temperature gradient as the major determinant of the location of the maximum of MAPE and, by extension, the location of the storm tracks. This is surprising considering that static stability constitutes one of the components of the decomposition. This revelation suggests that static stability plays an indirect role in storm track dynamics through temperature gradients, which is plausible since static stability can affect temperature gradients through its interaction with isentropic slopes. Furthermore, upper tropospheric temperature gradients can be modified by the convective lapse rate through its effect on the depth of the troposphere. The results contained herein can be used to supplement ongoing storm track work in moist atmospheres, using more comprehensive GCMs to understand storm track dynamics in an earth-like environment.

  7. Asian Summer Monsoon Intraseasonal Variability in General Circulation Models

    SciTech Connect

    Sperber, K R; Annamalai, H

    2004-02-24

    The goals of this report are: (1) Analyze boreal summer Asian monsoon intraseasonal variability general circulation models--How well do the models represent the eastward and northward propagating components of the convection and how well do the models represent the interactive control that the western tropical Pacific rainfall exerts on the rainfall over India and vice-versa? (2) Role of air-sea interactions--prescribed vs. interactive ocean; and (3) Mean monsoon vs. variability.

  8. Winter and summer simulations with the GLAS climate model

    NASA Technical Reports Server (NTRS)

    Shukla, J.; Straus, D.; Randall, D.; Sud, Y.; Marx, L.

    1981-01-01

    The GLAS climate model is a general circulation model based on the primitive equations in sigma coordinates on a global domain in the presence of orography. The model incorporates parameterizations of the effects of radiation, convection, large scale latent heat release, turbulent and boundary layer fluxes, and ground hydrology. Winter and summer simulations were carried out with this model, and the resulting data are compared to observations.

  9. Relationships among Narrow Bipolar Events, ``total'' lightning, and radar-inferred convective strength in Great Plains thunderstorms

    NASA Astrophysics Data System (ADS)

    Wiens, Kyle C.; Hamlin, Timothy; Harlin, Jeremiah; Suszcynsky, David M.

    2008-03-01

    Narrow Bipolar Events (NBEs) are a recently discovered distinct class of intracloud lightning discharges whose associated processes produce the most powerful very high frequency (VHF) radiation observed from lightning. NBEs are thus the prime candidate for proposed satellite-based VHF global lightning mapping and storm tracking missions. In this study, we offer a detailed evaluation of the Great Plains Los Alamos Sferic Array (LASA). We then statistically compare NBE rates to non-NBE lightning rates measured by both the LASA and the National Lightning Detection Network (NLDN) and to NEXRAD radar-inferred metrics of convective strength for thunderstorms in the Great Plains from May to July 2005. We find strong correlations between total lightning rate and convective strength, especially in terms of the height of 30 dBZ radar echo. However, we find much weaker correlations between NBE rate and non-NBE lightning rate and between NBE rate and radar-inferred convective strength. Though NBEs occur in the same storms as other lightning, they cluster more closely in both space and time and may be indicative of specific types of storms and/or specific stages in convective development. Indeed, we find that NBEs are more prevalent in, and perhaps indicative of, the strongest convection. However, even the strongest convection (as inferred by radar) does not always produce NBEs. We compare these results to past studies of NBEs which were based in Florida. We also briefly discuss the implications of these results for satellite-based VHF lightning detection.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  11. A 'Boscastle-type' quasi-stationary convective system over the UK Southwest Peninsula

    NASA Astrophysics Data System (ADS)

    Warren, Robert; Kirshbaum, Daniel; Plant, Robert; Lean, Humphrey

    2013-04-01

    Quasi-stationary convective systems (QSCSs) can produce extreme rainfall accumulations and have been responsible for many devastating flash floods worldwide. An oft-cited case from the UK is the 'Boscastle storm' which occurred on 16 August 2004 over the southwest peninsula of England. This system produced over 200 mm of precipitation in just four hours, leading to severe flooding in several coastal settlements. This presentation will focus on a QSCS from July 2010 which showed remarkable similarity to the Boscastle storm in terms of its location and structure, but produced much smaller rainfall accumulations and no flooding. First, observational data from the two cases will be compared to highlight three factors which made the Boscastle case more extreme: (1) higher rain rates, associated with a warmer and moister tropospheric column and deeper convective clouds; (2) a more stationary system, due to slower evolution of the large-scale flow; and (3) distribution of the heaviest precipitation over fewer river catchments. Results from numerical simulations of the July 2010 case (performed with convection-permitting configurations of the Met Office Unified Model) will then be presented. A control simulation, using 1.5-km grid spacing, reveals that convection was repeatedly initiated through lifting of low-level air parcels along a quasi-stationary coastal convergence line. Sensitivity tests suggest that this convergence line was a sea breeze front which temporarily stalled along the coastline due to the retarding influence of an offshore-direction background wind component. Several deficiencies are apparent in the 1.5-km model's representation of the storm system, including delayed convective initiation; however, significant improvements are observed when the grid length is reduced to 500 m. These result in part from an improved representation of the convergence line, which enhances the associated low-level ascent allowing air parcels to more readily reach their level of free convection. The implications of this finding for forecasting convective precipitation will be discussed.

  12. Spatial Resolution Dependence of Convective Organization Parameterization in CAM5

    NASA Astrophysics Data System (ADS)

    Hu, I. K.; Chen, B.; Mapes, B. E.

    2014-12-01

    This study investigates the role of convective organization at various spatial resolutions, using a unique parameterization of convective organization Ω as a prognostic variable in the Community Atmosphere Model. A unified shallow+deep convection scheme (a N-plume version of the University of Washington shallow convection scheme, currently with N=2) has Ω governing the properties and relative contributions of the plumes. Rain evaporation is the main source of convective organization, and the functions of organization within a plume ensemble include 1) plume radius enhancement (entrainment rate reduction) 2) the plume coverage (area or mass) that reaches the Level of Free Convection, and 3) the probabilities of overlap, and thus interactions, between plume ensemble members. Following from previous works (Mapes and Neale 2011, Chen and Mapes 2014), which used constant, linear coefficients to link Ω to the aforementioned functions, we test resolution-dependent and spatially-dependent coefficients for these functions to probe, and try to improve, simulations of regional climate systems such as South Asian Summer Monsoon.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  15. Magnetic Reconnection During Major Magnetospheric Storms

    NASA Astrophysics Data System (ADS)

    Hubert, B. A.; Milan, S. E.; Cowley, S. W. H.

    2014-12-01

    We combine imaging of the proton aurora from the SI12-IMAGE instrument with ionospheric convection measurement from the SuperDARN radar network to analyze the cycle of magnetic flux opening and closure of the Earth magnetosphere. Interaction between the solar wind and the Earth geomagnetic environment causes a reconfiguration of the magnetic field that connects the interplanetary magnetic field (IMF) to the geomagnetic field. This reconnection process produces open magnetic field lines (i.e. field lines of the magnetosphere that close through the interplanetary medium) that are dragged to the magnetotail by the solar wind flow, where they eventually reconnect again, back to a closed topology. The SI12 imaging of the Doppler-shifted Lyman-α emission of the proton aurora is used to estimate the location of the boundary separating open and closed field lines at ionospheric altitude. We then estimate the open magnetic flux of the Earth magnetosphere, encircled by this boundary. The rate of reconnection causing a variation of the open magnetic flux can be expressed as a voltage in application of Faraday's law. This voltage is measured along the open/closed field line boundary determined from the imaging data. The electric field associated with the voltage has two origins: motion of the boundary and the ionospheric field. We use the ionospheric electric field deduced from ionospheric convection measurement from the SuperDARN to estimate the reconnection voltage at the magnetopause (flux opening) and in the magnetotail (flux closure) accounting for the motion of the open/closed field line boundary determined from the SI12 images. The method is applied during several (strong) geomagnetic storms. These intervals are characterized by large values of open flux and reconnection rates, as a result of coupling between the solar wind and the geomagnetic environment. We present these results in terms of a magnetospheric mode that develops under strong coupling with the solar wind, a condition known to be prone to the development of sawtooth events, characterized by overloading of the magnetosphere with open magnetic flux.

  16. Overview of the Convection and Moisture Experiment (CAMEX)

    NASA Technical Reports Server (NTRS)

    Kakar, Ramesh; Goodman, Michael; Hood, robbie; Guillory, Anthony

    2006-01-01

    This paper presents an overview of the Convection and Moisture Experiment (CAMEX), including the field operations, aircraft platforms and missions, instrumentation, and data acquired during 1998 and 2001 field campaigns. A total of eight tropical storms and hurricanes were investigated during the CAMEX field campaigns including Bonnie, Danielle, Earl, and Georges during 1998 and Chantal, Erin, Gabrielle, and Humberto during 2001. Most of these storms were sampled with aircraft over the open ocean, but Hurricanes Bonnie (1998), Georges (1998), and Gabrielle (2001) also provided opportunities to monitor landfalling impacts. A few of the storms were sampled on multiple occasions during a course of several days. Most notable of these was Hurricane Humberto, which was sampled on three consecutive days during a cycle of both increasing and decreasing intensity change. Information collected for each of the eight CAMEX tropical storms as well as the Tropical Rainfall Measuring Mission validation activities are accessible via the CAMEX Web site and archived at the National Aeronautics and Space Administration Marshall Space Flight Center.

  17. Observation of moist convection in Jupiter's atmosphere. Galileo Imaging Team

    PubMed

    Gierasch; Ingersoll; Banfield; Ewald; Helfenstein; Simon-Miller; Vasavada; Breneman; Senske

    2000-02-10

    The energy source driving Jupiter's active meteorology is not understood. There are two main candidates: a poorly understood internal heat source and sunlight. Here we report observations of an active storm system possessing both lightning and condensation of water. The storm has a vertical extent of at least 50 km and a length of about 4,000 km. Previous observations of lightning on Jupiter have revealed both its frequency of occurrence and its spatial distribution, but they did not permit analysis of the detailed cloud structure and its dynamics. The present observations reveal the storm (on the day side of the planet) at the same location and within just a few hours of a lightning detection (on the night side). We estimate that the total vertical transport of heat by storms like the one observed here is of the same order as the planet's internal heat source. We therefore conclude that moist convection-similar to large clusters of thunderstorm cells on the Earth-is a dominant factor in converting heat flow into kinetic energy in the jovian atmosphere. PMID:10688191

  18. Summer research programs.

    PubMed

    Sutliff, Roy L

    2011-12-01

    A summer research experience is an excellent opportunity for undergraduate students to gain valuable research experience. With a little bit of planning, students can become familiar with the research area in which they are interested and begin to make connections with experts in the field. Time spent discussing goals for the project can yield peer-reviewed abstracts and publications. As a result, an application to graduate school can be greatly improved by a summer research experience, and students can have more options to consider as they embark on graduate training. PMID:22256733

  19. Stratospheric variability in summer

    NASA Technical Reports Server (NTRS)

    Rind, D.; Donn, W. L.; Robinson, W.

    1981-01-01

    Rocketsonde observations and infrasound results are used to investigate the variability of the summer stratopause region during one month in summer. Fluctuations of 2-3 days and about 16-day periods are evident, and they appear to be propagating vertically. In this month the 2-3 day oscillations have an amplitude envelope equal in period to the longer period oscillations, implying a connection between the two phenomena. Observations of the diurnal tide and shorter period variability during the month are also presented.

  20. Dust storms - Great Plains, Africa, and Mars

    NASA Technical Reports Server (NTRS)

    Woiceshyn, P. M.; Krauss, R.; Minzner, R.; Shenk, W.

    1977-01-01

    Dust storms in the Great Plains of North America and in the Sahara Desert are analyzed on the basis of imagery from the geostationary Synchronous Meteorological Satellite. The onset time, location and areal extent of the dust storms are studied. Over land surfaces, contrast enhancement techniques are needed to obtain an adequate picture of dust storm development. In addition, infrared imagery may provide a means of monitoring the strong horizontal temperature gradients characteristic of dust cloud boundaries. Analogies between terrestrial dust storms and the airborne rivers of dust created by major Martian dust storms are also drawn.

  1. Large Geomagnetic Storms: Introduction to Special Section

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.

    2010-01-01

    Solar cycle 23 witnessed the accumulation of rich data sets that reveal various aspects of geomagnetic storms in unprecedented detail both at the Sun where the storm causing disturbances originate and in geospace where the effects of the storms are directly felt. During two recent coordinated data analysis workshops (CDAWs) the large geomagnetic storms (Dst < or = -100 nT) of solar cycle 23 were studied in order to understand their solar, interplanetary, and geospace connections. This special section grew out of these CDAWs with additional contributions relevant to these storms. Here I provide a brief summary of the results presented in the special section.

  2. Combined buoyancy-thermocapillary convection

    NASA Technical Reports Server (NTRS)

    Homsy, G. M.

    1990-01-01

    Combined buoyancy-thermocapillary convection was studied in 2D and 3D. Fluid motion caused by thermally induced tension gradients on the free surface of a fluid is termed thermocapillary convection. It is well-known that in containerless processing of materials in space, thermocapillary convection is a dominant mechanism of fluid flow. Welding and crystal growth processes are terrestrial applications where thermocapillary convection has direct relevance.

  3. Predicting Airspace Capacity Impacts Using the Consolidated Storm Prediction for Aviation

    NASA Technical Reports Server (NTRS)

    Russell, Carl

    2010-01-01

    Convective weather is currently the largest contributor to air traffic delays in the United States. In order to make effective traffic flow management decisions to mitigate these delays, weather forecasts must be made as early and as accurately as possible. A forecast product that could be used to mitigate convective weather impacts is the Consolidated Storm Prediction for Aviation. This product provides forecasts of cloud water content and convective top heights at 0- to 8-hour look-ahead times. The objective of this study was to examine a method of predicting the impact of convective weather on air traffic sector capacities using these forecasts. Polygons representing forecast convective weather were overlaid at multiple flight levels on a sector map to calculate the fraction of each sector covered by weather. The fractional volume coverage was used as the primary metric to determine convection s impact on sectors. Results reveal that the forecasts can be used to predict the probability and magnitude of weather impacts on sector capacity up to eight hours in advance.

  4. Introducing Convective Cloud Microphysics to a Deep Convection Parameterization Facilitating Aerosol Indirect Effects

    NASA Astrophysics Data System (ADS)

    Alapaty, K.; Zhang, G. J.; Song, X.; Kain, J. S.; Herwehe, J. A.

    2012-12-01

    Short lived pollutants such as aerosols play an important role in modulating not only the radiative balance but also cloud microphysical properties and precipitation rates. In the past, to understand the interactions of aerosols with clouds, several cloud-resolving modeling studies were conducted. These studies indicated that in the presence of anthropogenic aerosols, single-phase deep convection precipitation is reduced or suppressed. On the other hand, anthropogenic aerosol pollution led to enhanced precipitation for mixed-phase deep convective clouds. To date, there have not been many efforts to incorporate such aerosol indirect effects (AIE) in mesoscale models or global models that use parameterization schemes for deep convection. Thus, the objective of this work is to implement a diagnostic cloud microphysical scheme directly into a deep convection parameterization facilitating aerosol indirect effects in the WRF-CMAQ integrated modeling systems. Major research issues addressed in this study are: What is the sensitivity of a deep convection scheme to cloud microphysical processes represented by a bulk double-moment scheme? How close are the simulated cloud water paths as compared to observations? Does increased aerosol pollution lead to increased precipitation for mixed-phase clouds? These research questions are addressed by performing several WRF simulations using the Kain-Fritsch convection parameterization and a diagnostic cloud microphysical scheme. In the first set of simulations (control simulations) the WRF model is used to simulate two scenarios of deep convection over the continental U.S. during two summer periods at 36 km grid resolution. In the second set, these simulations are repeated after incorporating a diagnostic cloud microphysical scheme to study the impacts of inclusion of cloud microphysical processes. Finally, in the third set, aerosol concentrations simulated by the CMAQ modeling system are supplied to the embedded cloud microphysical scheme to study impacts of aerosol concentrations on precipitation and radiation fields. Observations available from the ARM microbase data, the SURFRAD network, GOES imagery, and other reanalysis and measurements will be used to analyze the impacts of a cloud microphysical scheme and aerosol concentrations on parameterized convection.

  5. Storms of Mediterranean and Atlantic legends

    NASA Astrophysics Data System (ADS)

    Schoenenwald,