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Sample records for summer convective storms

  1. Radar Observations Of Lake Breeze Induced Summer Convective Storms

    NASA Astrophysics Data System (ADS)

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

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

  2. 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.

  3. 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.

  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. Modelling Convective Dust Storms in Large-Scale Weather and Climate Models

    NASA Astrophysics Data System (ADS)

    Pantillon, F.; Knippertz, P.; Marsham, J. H.; Panitz, H. J.; Bischoff-Gauss, I.

    2015-12-01

    Recent field campaigns have shown that convective dust storms - also known as haboobs or cold pool outflows - contribute a significant fraction of dust uplift over the Sahara and Sahel in summer. However, in-situ observations are sparse and convective dust storms are frequently concealed by clouds in satellite imagery. Therefore numerical models are often the only available source of information over the area. Here a regional climate model with explicit representation of convection delivers the first full seasonal cycle of convective dust storms over North Africa. The model suggests that they contribute one fifth of the annual dust uplift over North Africa, one fourth between May and October, and one third over the western Sahel during this season. In contrast, most large-scale weather and climate models do not explicitly represent convection and thus lack such storms.A simple parameterization of convective dust storms has recently been developed, based on the downdraft mass flux of convection schemes. The parameterization is applied here to a set of regional climate runs with different horizontal resolutions and convection schemes, and assessed against the explicit run and against sparse station observations. The parameterization succeeds in capturing the geographical distribution and seasonal cycle of convective dust storms. It can be tuned to different horizontal resolutions and convection schemes, although the details of the geographical distribution and seasonal cycle depend on the representation of the monsoon in the parent model. Different versions of the parameterization are further discussed with respect to differences in the frequency of extreme events. The results show that the parameterization is reliable and can therefore solve a long-standing problem in simulating dust storms in large-scale weather and climate models.

  6. Modelling Convective 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

    2016-04-01

    Recent field campaigns have shown that convective dust storms - also known as haboobs or cold pool outflows - contribute a significant fraction of dust uplift over the Sahara and Sahel in summer. However, in-situ observations are sparse and convective dust storms are frequently concealed by clouds in satellite imagery. Therefore numerical models are often the only available source of information over the area. Here a regional climate model with explicit representation of convection delivers the first full seasonal cycle of convective dust storms over North Africa. The model suggests that they contribute one fifth of the annual dust uplift over North Africa, one fourth between May and October, and one third over the western Sahel during this season. In contrast, most large-scale weather and climate models do not explicitly represent convection and thus lack such storms. A simple parameterization of convective dust storms has recently been developed, based on the downdraft mass flux of convection schemes. The parameterization is applied here to a set of regional climate runs with different horizontal resolutions and convection schemes, and assessed against the explicit run and against sparse station observations. The parameterization succeeds in capturing the geographical distribution and seasonal cycle of convective dust storms. It can be tuned to different horizontal resolutions and convection schemes, although the details of the geographical distribution and seasonal cycle depend on the representation of the monsoon in the parent model. Different versions of the parameterization are further discussed with respect to differences in the frequency of extreme events. The results show that the parameterization is reliable and can therefore solve a long-standing problem in simulating dust storms in large-scale weather and climate models.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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

  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. The Dynamics of Simulated Convective Storms in Hurricane Environments.

    NASA Astrophysics Data System (ADS)

    McCaul, Eugene Williamson, Jr.

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

  16. 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.

  17. 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.

  18. Particle Energization During Magnetic Storms with Steady Magnetospheric Convection

    NASA Astrophysics Data System (ADS)

    Kissinger, J.; Kepko, L.; Baker, D. N.; Kanekal, S. G.; Li, W.; McPherron, R. L.; Angelopoulos, V.

    2013-12-01

    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 explore how quasi-steady convection during steady magnetospheric convection (SMC) events affects 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 detail the behavior of the seed electron population for stormtime SMC events using the Van Allen Probes in the outer radiation belt and THEMIS in the plasma sheet and inner magnetosphere. Together, the two missions provide the ability to track particle transport and energization from the plasma sheet into the radiation belts. We present SMC events with Van Allen Probes/THEMIS conjunctions and compare plasma sheet fast flows/enhanced transport to radiation belt seed electron enhancements. Finally we utilize statistical analyses to quantify the relative importance of SMC events on radiation belt electron acceleration in comparison to isolated substorms.

  19. 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.

  20. 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

  1. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Hueso, Ricardo; Sánchez-Lavega, Agustín

    2004-11-01

    Moist convective storms constitute a key aspect in the global energy budget of the atmospheres of the giant planets. Among them, Saturn is known to develop the largest scale convective storms in the Solar System, the Great White Spots (GWS) which occur rarely and have been detected once every 30 years approximately. On the average, Saturn seems to show much less convective storms than Jupiter with smaller size and reduced frequency and intensity. Here we present detailed simulations of the onset and development of storms at the Equator and mid-latitudes of Saturn. These are the regions where most of the recent convective activity of the planet has been observed. We use a 3D anelastic model with parameterized microphysics (Hueso and Sánchez-Lavega, 2001, Icarus 151, 257) studying the onset and evolution of water and ammonia moist convective storms up to sizes of a few hundred km. Water storms, while more difficult to initiate than in Jupiter, can be very energetic, arriving to the 150 mbar level and developing vertical velocities on the order of 150 m s -1. Ammonia storms develop easier but with a much smaller intensity unless very large abundances of ammonia (10 times solar) are present in Saturn's atmosphere. The Coriolis forces play a major role in the morphology and properties of water based storms.

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

    NASA Astrophysics Data System (ADS)

    van den Heever, Susan; Grant, Leah

    2014-05-01

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

  5. The Numerical Simulation of Infrasound Generated by Convective Storms

    NASA Astrophysics Data System (ADS)

    Schecter, D.; Nicholls, M. E.

    2009-12-01

    Recent observations and theoretical considerations suggest that a developing tornado has a detectable signature in the infrasound of a severe weather system [A.J. Bedard Jr., Mon. Weather Rev., 133, 241 (2005)]. In order to reliably distinguish the vortex signal from extraneous noise, it is essential to advance current understanding of the various mechanisms that produce infrasound in atmospheric convection. Without detailed observations of the acoustic sources within a storm, numerical modeling may be the best method of investigation. Here, we consider the feasibility of using a special version of the Regional Atmospheric Modeling System (RAMS) that is customized to simulate aeroacoustics. Comparison to analytical results demonstrates that the customized model adequately generates the infrasound of tornado-like vortices, and of basic diabatic cloud processes. Sensitivity to the microphysics parameterization is briefly addressed. Provisional simulations suggest that a moderate-to-strong tornado can adiabatically generate infrasound of much greater intensity than the infrasound of a generic hail-producing thunderstorm, in the 0.1-3 Hz frequency range [D.A. Schecter et al., J. Atmos. Sci., 65, 685 (2008)]. More detailed numerical studies are underway to verify this conclusion, and to further understand the production of infrasound in a broad spectrum of convective systems, ranging from non-precipitating cumuli to tornadic thunderstorms.

  6. 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.

  7. 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

  8. 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

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  15. Upper tropospheric conditions in relation to the cloud top features of 15 August 2010 convective storms

    NASA Astrophysics Data System (ADS)

    Púčik, Tomáš; Valachová, Michaela; Zacharov, Petr

    2013-04-01

    This study focuses on 15 August 2010, when many severe convective storms occurred over parts of central and Eastern Europe, with some of these exhibiting various interesting cloud-top characteristics observed by weather satellites. The importance of the phenomena of cold-U and cold-ring features in the infrared brightness temperature enhanced imagery stems from the fact that storms exhibiting these features are very often accompanied by severe weather. Therefore, besides the general description of the atmospheric conditions in the area, we seek possible reasons for the different cloud-top appearance of these storms from the perspective of Meteosat Second Generation and polar-orbiting weather satellites. Two main issues are discussed in this paper - the unusually warm appearance of the cloud-top of the “Prague hailstorm” and the presence of cold-ring and cold-U shaped storms in close proximity to the warmer “Prague hailstorm”. Both of these issues prove that the storm top appearance is very sensitive to the upper tropospheric and lower stratospheric conditions, with the first one strongly reflecting variations in the tropopause height due to the presence of the jet-stream over the region. The second topic addresses the strength of the storm relative upper level winds as a major discriminator between the cold-U and cold-ring storm top categories. Due to the above mentioned facts, 15 August 2010 was selected as one of the prime cases of interest for the Convection Working Group.

  16. Links Between the Madden-Julian Oscillation and Severe Convective Storms in the U.S.

    NASA Astrophysics Data System (ADS)

    Barrett, B.

    2015-12-01

    Recent research has shown a tendency for severe convective storms to vary intraseasonally, including by phase of the Madden-Julian Oscillation (MJO). The MJO is the leading mode of atmospheric intraseasonal variability and is characterized by large regions (1000-5000 km) of anomalous convective activity that generally propagate eastward along the equator. Anomalous upper-troposphere heating associated with this convection generates poleward-propagating Rossby waves that interact with the preexisting extratropical circulation. The projection of this interaction onto the synoptic scale - via the favoring of troughs and ridges at certain positions - is the hypothesized mechanism by which the MJO modulates severe convection. However, one unexplored aspect of this modulation is the extent to which severe convection in winter and early-spring months, especially Jan-Mar, may be influenced by different phases of the MJO. While climatologically rarer than events later in spring, severe thunderstorms in winter and early spring still have potential to be high-impact weather events, especially as they often occur in populated areas of the southeast U.S. that have shown more vulnerability than other regions such as the southern or central plains. Results from other studies (not necessarily focused on the question of severe convective storms) have indicated statistically significant modulation of upper- and mid-tropospheric circulation (from 200 hPa to 700 hPa), surface temperature, and sea level pressure. Thus, it is possible that the MJO's influence also extends to severe storms, as these are ingredients known to affect the likelihood of convective activity in the U.S. Using a methodology similar to other recent MJO studies, the impacts of the MJO on tornado, hail, and wind activity from Jan-Mar will be tested as part of this larger project to understand intraseasonal variability of severe storms.

  17. Enhanced antisunward convection and F region scintillations at mid-latitudes during storm onset

    SciTech Connect

    Foster, J.C. ); Aarons, J. )

    1988-10-01

    Millstone Hill radar observations over a wide span of latitudes detail the onset of 300 m/s antisunward (westward) convection at mid and low latitudes in the morning sector as a region of storm-enhanced sunward convection retreats poleward. Ring current observations reported by Lui et al. (1987) suggest that the magnetospheric shielding layer was coincident with the observed reversal between sunward and antisunward convection. A strong southward component of the F region neutral wind is observed at latitudes equatorward of the convection reversal. These observations are in agreement with the model of Spiro et al. (1988), who find that storm-enhanced neutrral winds at latitudes equatorward of the shielding layer can generate a long-lived perturbation electric field in the inner magnetosphere. The observations show the growth of the subauroral electric field as the shielding boundary moves poleward. They observe 136-MHz scintillations in both the auroral sunwarrd convection region and the region of subauroral antisunward convection when the convection electric fields exceed 5 mV/m.

  18. 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.

  19. 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.

  20. The DYMECS project: The Dynamical and Microphysical Evolution of Convective Storms

    NASA Astrophysics Data System (ADS)

    Stein, Thorwald; Hogan, Robin; Hanley, Kirsty; Nicol, John; Plant, Robert; Lean, Humphrey; Clark, Peter; Halliwell, Carol

    2014-05-01

    A new frontier in weather forecasting is emerging by operational forecast models now being run at convection-permitting resolutions at many national weather services. However, this is not a panacea; significant systematic errors remain in the character of convective clouds and rainfall distributions. The DYMECS project (Dynamical and Microphysical Evolution of Convective Storms) is taking a fundamentally new approach to evaluate and improve such models: rather than relying on a limited number of cases, which may not be representative, we have gathered a large database of 3D storm structures on 40 convective days using an automated storm-tracking and scan-scheduling algorithm for the high resolution Chilbolton radar in southern England. These structures have been related to storm life-cycles derived by tracking features in the rainfall from the UK radar network, and compared statistically to simulated reflectivity fields from multiple versions of the Met Office model, varying horizontal grid length between 1.5 km and 100 m, and changing the sub-grid mixing and microphysics schemes. We also evaluated the scale and intensity of convective updrafts using a new radar technique. We find that the horizontal size of simulated convective clouds and the updrafts within them decreases with decreasing grid lengths down to 200 m, below which no further decrease is found. Comparison with observations reveals that at these resolutions, updrafts are about the right size (around 2 km across), but the clouds are typically too narrow and rain too intense (in both cases by around a factor of two), while progressing through their lifecycle too slowly. The scale error may be remedied by artificially increasing mixing length, but the microphysics scheme has little effect on either scale or intensity.

  1. Moist convection in hydrogen atmospheres and the frequency of Saturn's giant storms

    NASA Astrophysics Data System (ADS)

    Li, C.; Ingersoll, A. P.

    2015-12-01

    A giant planet-encircling storm occurred on Saturn on Dec. 5th, 2010 at planetographic latitude 37.7 N. 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 not clear 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%, which implies O/H at least 10 times the solar value. 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 vapor mixing ratio of 1.1%, the ammonia vapor is depleted down to 6 bars, the tropospheric warming is ~6 K, and the interval between two consecutive storms at one latitude is ~70 years. These values are consistent with observations.

  2. 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

  3. 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.

  4. What can simulated convective storms tell us about thunderstorm behavior under climate change?

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, C.

    2013-12-01

    Isolated convective storms are responsible for numerous high-impact weather events. Their frequency and intensity under the present climate change has been the subject of much speculation, and this uncertainty is magnified when considering that these storms are sensitive to modest changes in their ambient environments. In this work we use an idealized, cloud-resolving model to study the role of environmental changes on storm behavior. This approach is useful since it allows direct comparison of storm morphology between one environment (e.g., the present) and another (e.g., the future). Our current understanding is that for much of the globe, atmospheric temperature and water vapor will increase, and, at least in the middle latitudes, tropospheric wind shear may decrease owing to a weakening of the zonal temperature gradient that maintains the polar jet stream. The vertically integrated effects of temperature and water vapor can be summarized by the convective available potential energy (CAPE), a measure of buoyant energy available to updrafts. These two parameters, CAPE and tropospheric wind shear, are known to exert significant control on storm behavior and are explored herein. Between simulations, either CAPE or shear or both are varied (by 200 J kg-1 and 2 m s-1, respectively), and storm properties in the various environments are then compared. In 112 experiment pairs with CAPE increased and shear decreased, 56% of storms produce stronger updrafts, with some that are stronger by as much as 20 m s-1. However, the magnitude and sign of the change is strongly dependent on the starting values of CAPE and shear. For example, in simulations where CAPE is already >2000 J kg-1 and shear is weak, such as the moist tropics, small changes to either parameter actually work to reduce updraft intensity, by 5 to 10 m/s. In environments where CAPE is very low (400 J kg-1), addition of just 200 J kg-1 of buoyancy can be the difference between storms that last 30-40 minutes, and

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. North Atlantic summer storm tracks over Europe dominated by internal variability over the past millennium

    NASA Astrophysics Data System (ADS)

    Gagen, Mary H.; Zorita, Eduardo; McCarroll, Danny; Zahn, Matthias; Young, Giles H. F.; Robertson, Iain

    2016-08-01

    Certain large, sustained anomalies in European temperatures in the past millennium are probably the result of internal variation. Such internal variations can modulate regional temperatures away from the expected response to greenhouse gas forcing. Here we assess the causes of European summer temperature variability over the past millennium using temperature observations, simulations and reconstructions. We find multidecadal-mean summer temperatures have varied within a span of 1 K, largely controlled by external forcing. By contrast, we find subcontinental variations, described by the temperature contrast between northern and southern Europe (the meridional temperature gradient), vary with a span of 2 K, and are controlled by internal processes. These variations are the result of redistributions of precipitation and cloud cover linked to oscillations in the position of the summer storm track. In contrast to recent twentieth-century winter-time trends, variations of the summer storm track over the past millennium show a weak response to external forcing, and instead are dominated by stochastic internal variability. We argue that the response of European summer temperatures to anthropogenic greenhouse forcing is likely to be spatially modulated by the same stochastic internal processes that have caused periods of cool, wet summers in northern Europe over the last millennium.

  10. 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

  11. 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

  12. 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

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

    NASA Astrophysics Data System (ADS)

    Sander, J.; Dotzek, N.

    2010-09-01

    The impact of climate change on severe convection over Europe is assessed by deriving convection-indices on the basis of 3-dimensional meteorological fields of two simulations of the regional climate model CLM: one simulation for the past (1979-2000) and one for the future (2079-2100). Verification of the method is attained by comparing the results with sounding-derived parameters on the basis of radiosondes, ERA-40 reanalysis and severe storm reports from the European Severe Weather Database (ESWD). Additionally, we will look at the relation between thunderstorm severity potential (TSP), Convective Inhibition (CIN), Convective Available Potential Energy (CAPE), deep-layer wind shear (DLS) and Lamb's circulation weather types (CWT) to investigate how the synoptic situation influences severe convection over continental Europe. If special circulation patterns change in the future, this might have an effect on the development of thunderstorms due to the modification in transport and advection of air mass. This study is part of the severe weather research project RegioExAKT (www.regioexakt.de).

  14. 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.

  15. 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

  16. 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.

  17. 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.

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

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1981-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  20. 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.

  1. 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.

  2. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  4. Weakening of the mid-latitude summer nighttime anomaly during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Liu, Huixin; Yamamoto, Mamoru

    2011-04-01

    This brief report presents geomagnetic storm effects on the formation and characteristics of the midlatitude summer nighttime anomaly (MSNA). This anomaly is a phenomenon where the diurnal variation of the plasma density maximizes at night instead of day. Under disturbed geomagnetic conditions, the MSNA is found to have smaller spatial coverage, lower magnitude of the reversed diurnal cycle, and shorter duration of the nighttime enhancement. All these features demonstrate a weakening of the MSNA. In addition, the nighttime maximum tends to occur at earlier local time. These effects can be reasonably understood in the frame of storm-induced equatorward wind and the molecular-rich air it carries along with. For instance, the shrink of the spatial coverage is essentially a dominant effect of the molecular-rich air, which tends to deplete the plasma significantly on the poleward edge of the MSNA region. On the other hand, the smaller magnitude and the shorter duration seem to be mainly caused by the storm-induced equatorward wind. Storm effects presented here add further evidence to the pivot role of effective neutral wind in the formation of MSNA.

  5. Surface fluxes and convective boundary layer instability in summer over harvested wheat fields in Oklahoma

    NASA Astrophysics Data System (ADS)

    Li, W.; Barros, A. P.

    2008-05-01

    Vertical profiles of wind, pressure, air temperature and humidity up to 500 m obtained from measurements by a tethersonde system were used in combination with upper level temperature and humidity soundings from Rapid Update Cycle (RUC), to calculate Convective Available Potential Energy (CAPE) in an unstable boundary layer. The surface fluxes of sensible and latent heat were also calculated based on turbulent similarity theory for the atmospheric surface layer. The measurements were performed during the Cloud and Land Surface Interaction Campaign (CLASIC) June 2007 that includes pre-storm and post-storm conditions for a record monthly rainfall in excess of 300 mm at the site. The daytime trajectories of the surface layer in the Relative-Humidity and Bowen Ratio phase-space are consistent with the rainfall and aridity attractors in previous studies, with strong decrease in the post-storm periods. The decrease of Bowen ratio was the result of a strong decrease in the magnitude of sensible heat fluxes. The latent heat fluxes in the post-storm environment were not significantly different from the pre-storm environment, which is explained by a significant decrease in the net radiation. High soil moisture and increased moisture in boundary layer in the post-storm environment led to sustained low-level instability and daily evening showers. The diurnal cycle of potential temperature and specific humidity during the duration of the field campaign with an emphasis on conditions before and after one major rainy event are also discussed in this study.

  6. Enhanced summer convective rainfall at Alpine high elevations in response to climate warming

    NASA Astrophysics Data System (ADS)

    Giorgi, Filippo; Torma, Csaba; Coppola, Erika; Ban, Nikolina; Schär, Christoph; Somot, Samuel

    2016-08-01

    Global climate projections consistently indicate a future decrease in summer precipitation over the European Alps. However, topography can substantially modulate precipitation change signals. For example, the shadowing effect by topographic barriers can modify winter precipitation change patterns, and orographic convection might also play an important role. Here we analyse summer precipitation over the Alpine region in an ensemble of twenty-first-century projections with high-resolution (~12 km) regional climate models driven by recent global climate model simulations. A broad-scale summer precipitation reduction is projected by both model ensembles. However, the regional models simulate an increase in precipitation over the high Alpine elevations that is not present in the global simulations. This is associated with increased convective rainfall due to enhanced potential instability by high-elevation surface heating and moistening. The robustness of this signal, which is found also for precipitation extremes, is supported by the consistency across models and future time slices, the identification of an underlying mechanism (enhanced convection), results from a convection-resolving simulation, the statistical significance of the signal and the consistency with some observed trends. Our results challenge the picture of a ubiquitous decrease of summer precipitation over the Alps found in coarse-scale projections.

  7. 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

  8. Classification and Analysis of Four Types of Elevated Nocturnal Convective Initiation During Summer 2015

    NASA Astrophysics Data System (ADS)

    Stelten, S. A.; Gallus, W. A., Jr.

    2015-12-01

    A large portion of precipitation seen in the Great Plains region of the United States falls from nocturnal convection. Quite often, nocturnally initiated convection may grow upscale into a Mesoscale Convective System (MCS) that in turn may cause high impact weather events such as severe wind, flooding, and even tornadoes. Thus, correctly predicting nocturnal convective initiation is an integral part of forecasting for the Great Plains. Unfortunately, it is also one of the most challenging aspects of forecasting for this region. Many forecasters familiar with the Great Plains region have noted that elevated nocturnal convective initiation seems to favor a few distinct and rather diverse modes, which pose varying degrees of forecasting difficulties. This study investigates four of these modes, including initiation caused by the interaction of the low level jet and a frontal feature, initiation at the nose of the low level jet without the presence of a frontal feature, linear features ahead of and perpendicular to a forward propagating MCS, and initiation occurring with no discernible large scale forcing mechanism. Improving elevated nocturnal convective initiation forecasts was one of the primary goals of the Plains Elevated Convection At Night (PECAN) field campaign that took place from June 1 to July 15, 2015, which collected a wealth of convective initiation data. To coincide with these data sets, nocturnal convective initiation episodes from the 2015 summer season were classified into each of the aforementioned groups. This allowed for a thorough investigation of the frequency of each type of initiation event, as well as identification of typical characteristics of the atmosphere (forcing mechanisms present, available instability, strength/location of low level jet, etc.) during each event type. Then, using archived model data and the vast data sets collected during the PECAN field campaign, model performance during PECAN for each convective initiation mode was

  9. 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.

  10. 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

  11. Assessment of the European Severe Convective Storm Climatology using Reanalysis Data

    NASA Astrophysics Data System (ADS)

    Pistotnik, Georg; Groenemeijer, Pieter; Kühne, Thilo

    2013-04-01

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

  12. Simulation and Analysis of Infrasound Generated by Convective Storms and Tornadoes

    NASA Astrophysics Data System (ADS)

    Schecter, D.; Nicholls, M.

    2011-12-01

    Observational studies have shown that severe storms can emit abnormally strong, sustained infrasound in the 0.5-5 Hz frequency range. There is reason to believe that the infrasonic emissions come from developing and mature tornadoes, but some ambiguity remains in the interpretation of the data. It is fair to say that we do not yet fully understand the conditions for which a vortex signal is discernible from the infrasound of non-tornadic sources within a storm. There is a pressing need to advance our fundamental understanding of the different mechanisms that generate infrasound in atmospheric convection. To this end, numerical modeling may be the best method of investigation. We are exploring this avenue of research with a customized version of the Regional Atmospheric Modeling System (c-RAMS). Previous studies have established the basic credibility of c-RAMS for simulating acoustic phenomena. More recently, we have developed a convenient method for diagnosing the primary sources of infrasound in complex storm simulations. The method is based on a generalization of Lighthill's acoustic analogy, and is aptly illustrated in the context of a simulated cumulonimbus. Applying the diagnostic method to this system, we find that the 0.1-1 Hz infrasound of diabatic processes in the hail-to-rain transition layer dominates that of turbulent wind fluctuations covering the entire storm. We have also used c-RAMS to investigate the infrasound of tornadoes created by artificial buoyancy forcing in a dry, rotational environment. The simulated tornadoes have realistic structure, but their cores are typically quiet in the frequency range of interest. In other words, we find that dry fluctuations of the vortex core may not provide a robust source of discernible infrasound. Apparent deficiencies of earlier theories that predicted otherwise will be addressed. This work was supported by NSF grant AGS-0832320.

  13. Recent Trends of Summer Convective and Stratiform Precipitation in Mid-Eastern China

    PubMed Central

    Fu, Yunfei; Chen, Fengjiao; Liu, Guosheng; Yang, Yuanjian; Yuan, Renmin; Li, Rui; Liu, Qi; Wang, Yu; Zhong, Lei; Sun, Liang

    2016-01-01

    Many studies have reported on the trends of precipitation in Mid-Eastern China (EC). However, the trends of convective and stratiform precipitation are still unknown. Here, we examine the trends of summer convective and stratiform precipitation in EC from 2002 to 2012 on the basis of the TRMM observations. Results revealed that the rain frequency (RF) for both convective and stratiform precipitation increased in majority regions of Southern EC (SEC), but decreased in Northwest part of Northern EC (NEC). The decreasing rate of RF for stratiform precipitation in NEC is twice as much as that for convective precipitation, while the increase of convective precipitation in SEC is more evident than stratiform precipitation. The rain rate (RR) exhibited a decreasing trend in most portions of EC for both convective and stratiform precipitation. In SEC, neither PW nor WVT has good ability in explaining the precipitation variability. However, in NEC, PW is closely correlated to convective RF and WVT is more closely related to stratiform RF. PMID:27604846

  14. Recent Trends of Summer Convective and Stratiform Precipitation in Mid-Eastern China.

    PubMed

    Fu, Yunfei; Chen, Fengjiao; Liu, Guosheng; Yang, Yuanjian; Yuan, Renmin; Li, Rui; Liu, Qi; Wang, Yu; Zhong, Lei; Sun, Liang

    2016-01-01

    Many studies have reported on the trends of precipitation in Mid-Eastern China (EC). However, the trends of convective and stratiform precipitation are still unknown. Here, we examine the trends of summer convective and stratiform precipitation in EC from 2002 to 2012 on the basis of the TRMM observations. Results revealed that the rain frequency (RF) for both convective and stratiform precipitation increased in majority regions of Southern EC (SEC), but decreased in Northwest part of Northern EC (NEC). The decreasing rate of RF for stratiform precipitation in NEC is twice as much as that for convective precipitation, while the increase of convective precipitation in SEC is more evident than stratiform precipitation. The rain rate (RR) exhibited a decreasing trend in most portions of EC for both convective and stratiform precipitation. In SEC, neither PW nor WVT has good ability in explaining the precipitation variability. However, in NEC, PW is closely correlated to convective RF and WVT is more closely related to stratiform RF. PMID:27604846

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

    NASA Technical Reports Server (NTRS)

    Moore, Patrick D.; Ray, Peter S.

    1989-01-01

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

  16. 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.

  17. 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

  18. The DYMECS Project: A Statistical Approach for the Evaluation of Convective Storms in High-Resolution NWP Models

    NASA Astrophysics Data System (ADS)

    Stein, Thorwald; Hogan, Robin; Hanley, Kirsty; Clark, Peter; Halliwell, Carol; Lean, Humphrey; Nicol, John; Plant, Robert

    2016-04-01

    National weather services increasingly use convection-permitting simulations to assist in their operational forecasts. The skill in forecasting rainfall from convection is much improved in such simulations compared to global models that rely on parameterisation schemes, but it is less obvious if and how increased model resolution or more advanced mixing and microphysics schemes improve the physical representation of convective storms. Here, we present a novel statistical approach using high-resolution radar data to evaluate the morphology, dynamics, and evolution of convective storms over southern England. In the DYMECS project (Dynamical and Microphysical Evolution of Convective Storms) we have used an innovative track-and-scan approach to target individual storms with the Chilbolton radar, which measures cloud and precipitation at scales less than 300m out to 100km. These radar observations provide three-dimensional storm volumes and estimates of updraft core strength and sizes at adequate scales to test high-resolution models. For two days of interest, we have run the Met Office forecast model at its operational configuration (1.5km grid length) and at grid lengths of 500m, 200m, and 100m. Radar reflectivity and Doppler winds were simulated from the model cloud and wind output for a like-with-like comparison against the radar observations. Our results show that although the 1.5km simulation produces similar domain-averaged rainfall as the other simulations, the majority of rainfall is produced from storms that are a factor 1.5-2 larger than observed as well as longer lived, while the updrafts of these storms are an order of magnitude greater than estimated from observations. We generally find improvements as model resolution increases, although our results depend strongly on the mixing-length parameter in the model turbulence scheme. Our findings highlight the promising role of high-resolution radar data and observational strategies targeting individual storms

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

    NASA Astrophysics Data System (ADS)

    Lee, Tsengdar John

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Lee, Tsengdar John

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  2. Dynamics of the AMPERE Region 1 Birkeland current oval during storms, substorms and steady magnetospheric convection

    NASA Astrophysics Data System (ADS)

    Baker, J. B.; Clausen, L.; Ruohoniemi, J. M.; Milan, S. E.; Kissinger, J.; Anderson, B. J.; Wing, S.

    2012-12-01

    Using radial current densities provided by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) we employ a fitting scheme to identify the location of the maximum Region 1 field-aligned (Birkeland) current at all magnetic local times. We call this parameter the "R1 oval" and we investigate its behavior during various modes of magnetospheric activity such as storms, substorms and steady magnetospheric convection (SMCs). Results show the following: (1) during substorms the radius of the R1 oval undergoes a cyclic inflation and contraction which matches the standard paradigm for substorm growth (loading) and expansion (unloading); (2) during SMCs the R1 oval is relatively steady consistent with balanced dayside and nightside reconnection during these events; and (3) during magnetic storms the size of the R1 oval is strongly correlated with the strength of the ring current specified by the Sym-H index. We also examine the behavior of the R1 oval in the northern and southern hemispheres simultaneously as a function of season in an effort to understand the role that internal magnetosphere-ionosphere coupling influences may play in modulating the response of the magnetosphere during these various types of events.

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

    SciTech Connect

    Park, S.K.; Droegemeier, K.K.; Bischof, C.; Knauff, T.

    1994-06-01

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

  4. 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

  5. A two-moment cloud microphysics parameterization for mixed-phase clouds. Part 2: Maritime vs. continental deep convective storms

    NASA Astrophysics Data System (ADS)

    Seifert, A.; Beheng, K. D.

    2006-02-01

    A systematic modeling study investigates the effects of cloud condensation nuclei (CCNs) on the evolution of mixed-phase deep convective storms. Following previous studies the environmental conditions like buoyancy and vertical wind shear are varied to simulate different storm types like ordinary single cells, multicells and supercells. In addition, the CCN characteristics are changed from maritime to continental conditions. The results reveal very different effects of continentality on the cloud microphysics and dynamics of the different storms. While a negative feedback on total precipitation and maximum updraft velocity is found for ordinary single cells and supercell storms, a positive feedback exists for multicell cloud systems. The most important link between CCN properties, microphysics and dynamics is the release of latent heat of freezing.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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 developing and decaying modes are identified. Based on the multiple linear regression method, the East Asia Rainfall Index (EARI) is developed by using the interannual variability of the normalized Maritime continent-WTP Indices (MPIs), as potentially useful predictors for rainfall prediction over East Asia, obtained from the above two main patterns. For East Asian summer rainfall, the EARI has superior performance to the East Asia summer monsoon index or each MPI. Therefore, the regressed rainfall from EARI also shows a strong relationship with the observed East Asian summer rainfall pattern. In addition, we evaluate the prediction skill of the East Asia reconstructed rainfall obtained by hybrid dynamical-statistical approach using the cross-validated EARI from the individual models and their MME. The results show that the rainfalls reconstructed from simulations capture the general features of observed precipitation in East Asia quite well. This study convincingly demonstrates that rainfall prediction skill is considerably improved by using a hybrid dynamical-statistical approach compared to the dynamical forecast alone.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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 developing and decaying modes are identified. Based on the multiple linear regression method, the East Asia Rainfall Index (EARI) is developed by using the interannual variability of the normalized Maritime continent-WTP Indices (MPIs), as potentially useful predictors for rainfall prediction over East Asia, obtained from the above two main patterns. For East Asian summer rainfall, the EARI has superior performance to the East Asia summer monsoon index or each MPI. Therefore, the regressed rainfall from EARI also shows a strong relationship with the observed East Asian summer rainfall pattern. In addition, we evaluate the prediction skill of the East Asia reconstructed rainfall obtained by hybrid dynamical-statistical approach using the cross-validated EARI from the individual models and their MME. The results show that the rainfalls reconstructed from simulations capture the general features of observed precipitation in East Asia quite well. This study convincingly demonstrates that rainfall prediction skill is considerably improved by using a hybrid dynamical-statistical approach compared to the dynamical forecast alone.

  8. Summer insolation is the primary driver for orbital-scale dust storm variability in East Asia

    NASA Astrophysics Data System (ADS)

    Serno, Sascha; Winckler, Gisela; Anderson, Robert F.; Jaccard, Samuel L.; Kienast, Stephanie S.; Haug, Gerald H.

    2016-04-01

    Eolian dust plays an important role in the global climate system through its influence on radiation, albedo and precipitation properties, and through delivering micronutrients like iron to the oceans. Glacial periods of Earth's climate are recognized to be dustier than interglacials, but the conditions leading to greater dust mobilization are poorly defined. We present a high-resolution dust flux record based on 230Th-normalised 4He flux from Ocean Drilling Program (ODP) site 882 in the Subarctic North Pacific covering the last 170,000 years. Today, dust storms in the vast dry regions of East Asia are almost exclusively springtime phenomena, due to a specific set of climate conditions driven by the seasonal evolution of the meridional temperature gradient between high and low latitudes. The dust flux record points to high dust storm activity in East Asia during cold periods, with highest dust flux during Marine Isotope Stages 4 and 5d. We interpret periods of higher dust supply as the result of an expansion of the dust season into the summer, primarily controlled by reduced summer insolation at high latitudes and resulting lower air temperatures in Siberia over orbital timescales. Changes in the extent of the large Northern Hemisphere ice sheets in North America and Fennoscandinavia, and atmospheric teleconnections, act as a secondary control. On millennial timescales, the occurrence of Heinrich Stadials 1 and 11 signals during the last two terminations in Subarctic North Pacific dust records indicates that dust flux variability over millennial timescales was influenced by climate changes in the North Atlantic.

  9. Idealized studies of convective summer precipitation in a cloud-resolving model

    NASA Astrophysics Data System (ADS)

    Schlemmer, Linda; Hohenegger, Cathy; Bretherton, Christopher; Schmidli, Jürg; Schär, Christoph

    2010-05-01

    Climate change is expected to moisten the atmosphere and to intensify the hydrological cycle. In the global mean, precipitation is projected to increase, but for Europe climate models suggest that mean summer precipitation will decrease. However, despite this decrease in mean, heavy precipitation events are projected to occur more frequently. The credibility of these projections, with decreases in mean amounts but increases in peak intensity, is somewhat limited, as convection is parameterized in current climate models due to its small-scale nature. Differences between climate models are especially large in summer, when synoptic-scale forcing is weak and the chosen model formulation has a great influence. Here we investigate the sensitivity of convection to ambient temperature and humidity profiles in a cloud-resolving model (CRM), using a spatial resolution of 500 m - 2 km. The modeling strategy includes an idealized set-up with explicit convection and a full set of parameterizations. The variables are relaxed towards the prescribed profiles and soil conditions, but the relaxation is weak in the lower troposphere and upper soil, such as to allow the development of a diurnal boundary layer. The model is run for 30 days, after which the diurnal cycle approximately repeats itself. Analysis is conducted for the last 15 days of the simulations. A systematic set of experiments with different stratification and humidity profiles is performed. We confirm that the temperature stratification of the environment has a dominant influence on the amount of precipitation by modifying the stability of the atmosphere and thereby the depth and intensity of convection. A more unstable stratification leads to deeper convective clouds and increased amounts of precipitation. In a more stable atmosphere convection remains shallow and precipitation amounts are small. The moisture profile influences the timing and duration of the precipitation period. Simulations with a drier atmosphere

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  11. A radar-based verification of precipitation forecast for local convective storms

    NASA Astrophysics Data System (ADS)

    Rezacova, Daniela; Sokol, Zbynek; Pesice, Petr

    2007-02-01

    Local flash flood storms with a rapid hydrological response are a real challenge for quantitative precipitation forecasting (QPF). It is relevant to assess space domains, to which the QPF approaches are applicable. In this paper an attempt is made to evaluate the forecasting capability of a high-resolution numerical weather prediction (NWP) model by means of area-related QPF verification. The results presented concern two local convective events, which occurred in the Czech Republic (CR) on 13 and 15 July 2002 and caused local flash floods. We used the LM COSMO model (Lokall Model of the COSMO consortium) adapted to the horizontal resolution of 2.8 km over a model domain covering the CR. The 18 h forecast of convective precipitation was verified by using radar rainfall totals adjusted to the measured rain gauge data. The grid point-related root mean square error (RMSE) value was calculated over a square around the grid point under the assumption that rainfall values were randomly distributed within the square. The forecast accuracy was characterized by the mean RMSE over the whole verification domain. We attempt to show a dependence of both the RMSE field and the mean RMSE on the square size. The importance of a suitable merger between the radar and rain gauge datasets is demonstrated by a comparison between the verification results obtained with and without the gauge adjustment. The application of verification procedure demonstrates uncertainties in the precipitation forecasts. The model was integrated with initial conditions shifted by 0.5° distances. The four verifications, corresponding to the shifts in the four directions, show differences in the resulting QPF, which depend on the size of verification area and on the direction of the shift.

  12. 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.

  13. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  15. Propagation of Mesoscale Convective Systems over India in the Boreal Summer Monsoon Season

    NASA Astrophysics Data System (ADS)

    Phadtare, J. A.; Bhat, G. S.

    2015-12-01

    With an automated cloud tracking algorithm, we have analysed the propagation of mesoscale convective systems (MCSs) over Indian region in the boreal summer monsoon season (June-September). We used half hourly infrared images of a geostationary satellite KALPANA-I for the study. The data covers four monsoon seasons (2010,12,13,and 14). Mesoscale convective systems (MCSs) over the Indian land show a prominent westward propagation, which is opposite to the lower tropospheric monsoonal westerlies. The mechanism associated with these propagations seems robust, i.e. it appears in all the events. The propagation seems to be a result of internal dynamics of MCS, and not forced by any external agent. The mechanism is prevalent through out the monsoon season, but absent in pre- and post-monsoon season. The zonal convective streaks associated with the large MCSs have a spatial and temporal scales of 1000 km and 1 day respectively, with a westward speed of 18 m/s. These streaks resemble the westward propagating inertial-gravity (WIG) type of wave propagation. Thus, we speculate that, the MCSs over India in the summer monsoon season trigger WIG waves. And the subsequent propagation of MCS is coupled to this wave signal. Most of the large MCSs are associated with the synoptic scale monsoon depressions. Mean propagation of MCSs over Bay of Bengal (BoB) is of more complex nature. There seems to be more than one propagation mechanism which are active over BoB in the summer monsoon season. The selection of propagation mechanism by the BoB MCSs might depend on the phase of diurnal cycle or intra-seasonal oscillation, MCS size, and its location over the bay.

  16. 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.

  17. 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

  18. Wet scavenging of soluble gases in DC3 deep convective storms using WRF-Chem simulations and aircraft observations

    NASA Astrophysics Data System (ADS)

    Bela, Megan M.; Barth, Mary C.; Toon, Owen B.; Fried, Alan; Homeyer, Cameron R.; Morrison, Hugh; Cummings, Kristin A.; Li, Yunyao; Pickering, Kenneth E.; Allen, Dale J.; Yang, Qing; Wennberg, Paul O.; Crounse, John D.; St. Clair, Jason M.; Teng, Alex P.; O'Sullivan, Daniel; Huey, L. Gregory; Chen, Dexian; Liu, Xiaoxi; Blake, Donald R.; Blake, Nicola J.; Apel, Eric C.; Hornbrook, Rebecca S.; Flocke, Frank; Campos, Teresa; Diskin, Glenn

    2016-04-01

    We examine wet scavenging of soluble trace gases in storms observed during the Deep Convective Clouds and Chemistry (DC3) field campaign. We conduct high-resolution simulations with the Weather Research and Forecasting model with Chemistry (WRF-Chem) of a severe storm in Oklahoma. The model represents well the storm location, size, and structure as compared with Next Generation Weather Radar reflectivity, and simulated CO transport is consistent with aircraft observations. Scavenging efficiencies (SEs) between inflow and outflow of soluble species are calculated from aircraft measurements and model simulations. Using a simple wet scavenging scheme, we simulate the SE of each soluble species within the error bars of the observations. The simulated SEs of all species except nitric acid (HNO3) are highly sensitive to the values specified for the fractions retained in ice when cloud water freezes. To reproduce the observations, we must assume zero ice retention for formaldehyde (CH2O) and hydrogen peroxide (H2O2) and complete retention for methyl hydrogen peroxide (CH3OOH) and sulfur dioxide (SO2), likely to compensate for the lack of aqueous chemistry in the model. We then compare scavenging efficiencies among storms that formed in Alabama and northeast Colorado and the Oklahoma storm. Significant differences in SEs are seen among storms and species. More scavenging of HNO3 and less removal of CH3OOH are seen in storms with higher maximum flash rates, an indication of more graupel mass. Graupel is associated with mixed-phase scavenging and lightning production of nitrogen oxides (NOx), processes that may explain the observed differences in HNO3 and CH3OOH scavenging.

  19. 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.

  20. Sensitivity of summer ensembles of fledgling superparameterized U.S. mesoscale convective systems to cloud resolving model microphysics and grid configuration

    DOE PAGESBeta

    Elliott, Elizabeth J.; Yu, Sungduk; Kooperman, Gabriel J.; Morrison, Hugh; Wang, Minghuai; Pritchard, Michael S.

    2016-05-01

    The sensitivities of simulated mesoscale convective systems (MCSs) in the central U.S. to microphysics and grid configuration are evaluated here in a global climate model (GCM) that also permits global-scale feedbacks and variability. Since conventional GCMs do not simulate MCSs, studying their sensitivities in a global framework useful for climate change simulations has not previously been possible. To date, MCS sensitivity experiments have relied on controlled cloud resolving model (CRM) studies with limited domains, which avoid internal variability and neglect feedbacks between local convection and larger-scale dynamics. However, recent work with superparameterized (SP) GCMs has shown that eastward propagating MCS-likemore » events are captured when embedded CRMs replace convective parameterizations. This study uses a SP version of the Community Atmosphere Model version 5 (SP-CAM5) to evaluate MCS sensitivities, applying an objective empirical orthogonal function algorithm to identify MCS-like events, and harmonizing composite storms to account for seasonal and spatial heterogeneity. A five-summer control simulation is used to assess the magnitude of internal and interannual variability relative to 10 sensitivity experiments with varied CRM parameters, including ice fall speed, one-moment and two-moment microphysics, and grid spacing. MCS sensitivities were found to be subtle with respect to internal variability, and indicate that ensembles of over 100 storms may be necessary to detect robust differences in SP-GCMs. Furthermore, these results emphasize that the properties of MCSs can vary widely across individual events, and improving their representation in global simulations with significant internal variability may require comparison to long (multidecadal) time series of observed events rather than single season field campaigns.« less

  1. Effects of vertical wind shear on convective development during a landfall of severe tropical storm Bilis (2006)

    NASA Astrophysics Data System (ADS)

    Wang, Donghai; Li, Xiaofan; Tao, Wei-Kuo; Wang, Yuan

    2009-10-01

    Effects of vertical wind shear on convective development during the landfall of tropical storm Bilis (2006) are investigated with a pair of sensitivity experiments using a two-dimensional cloud-resolving model. The validated simulation data from Wang et al. [Wang, D., Li, X., Tao, W.-K., Liu, Y., Zhou, H., 2009: Torrential rainfall processes associated with a landfall of severe tropical storm Bilis (2006): A two-dimensional cloud-resolving modeling study. Atmos. Res., 91, 94-104.] are used as the control experiment. The difference between the control and sensitivity experiments is that vertically varying zonal winds in the control experiment are replaced by their mass-weighted means in the sensitivity experiment. The imposed vertical velocity with ascending motion in the upper troposphere and descending motion in the lower troposphere is responsible for dominant stratiform rainfall on 15 July. The vertical wind shear does not have important impacts on development of stratiform rainfall. One day later, imposed upward motion extends to the lower troposphere. The inclusion of negative vertical wind shear produces well-organized convection and strong convective rainfall because it causes kinetic energy transfer from large-scale forcing to perturbation circulations.

  2. 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.

  3. 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).

  4. 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.

  5. 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.

  6. 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

  7. 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).

  8. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  10. 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.

  11. 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.

  12. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  14. Development of The Convective-boundary Layer On A Coastal Site: Summer and Winter Field Measurements.

    NASA Astrophysics Data System (ADS)

    Mantilla, E.; Sanz, M. J.; Millán., M. M.

    Within the framework of the EU project RECAB ("Regional Assessment and Model- ing of the Carbon Balance of Europe", EVK2-1999-00236), during July and December of 2001, convective boundary-layer measurements were performed systematically for several days at the coastline near El Saler (Valencia, Spain). A tethersonde sound- ing system was used, with a 1000 m maximum altitude. The measurement strategy included the realization of different profiles during the day: before or about sunrise to determine the characteristics of the drainage flow; at about the time of maximum boundary-layer development after noon; and in the afternoon-evening, to show the collapse of the diurnal flow. The objective was to document experimentally the struc- ture and daily evolution of the coastal boundary layer in the area, as well as to show seasonal variability in response to differences in mesoscale forcing. One of the most important aspects registered in the profiles, and expanding the previous evidences on the western Mediterranean coast, is the intense compensatory sinking on the coast oc- curring within the general subsidence process related to the persistent high pressure system in these latitudes during the summer period in response to the development of the sea breeze coastal cycles. This extra sinking, not present in the winter mea- surements (due to the fact that in this period meteorological processes are dominated by higher scale structures), gives rise to a rich thermal structure in the first hundreds meters of the atmosphere, creating intense superadiabatic lapse rates (a very strati- fied structure can often be appreciated, where different more-or-less uncoupled layers persist), which suppose an important barrier to the vertical diffusion of any surface emissions. This fact is very important for understanding the general process of the surface-atmosphere interchange mechanisms, and especially for modeling such pro- cesses with simple mixing layer schemes.

  15. Convection

    NASA Astrophysics Data System (ADS)

    Britz, Dieter

    Convection has long been coupled with electrochemistry, and the name hydrodynamic voltammetry has become standard. In electroanalytical chemistry we mainly seek reproducible conditions. These are almost always attained by systems in which a steady convective state is achieved, although not always. Thus, the once popular dropping mercury electrode (see texts such as [74, 257]) has convection around it, but is never in steady state; it might be called a reproducible periodic dynamic state.

  16. Variation of Ice Crystal Size, Shape and Asymmetry Parameter in Tops of Convective Storm Systems Observed during SEAC4RS

    NASA Astrophysics Data System (ADS)

    van Diedenhoven, B.; Cairns, B.; Fridlind, A. M.; Ackerman, A. S.

    2014-12-01

    The sizes and shapes of ice particles in tops of convective storms have a significant impact on their radiative properties. Ice crystal sizes and shapes likely vary with altitude, environmental conditions and convective strength, but these relationships are not well characterized. The rich dataset of the NASA SEAC4RS field campaign offers unique perspectives to further identify variations of ice crystal sizes and shapes and their relations to environmental and dynamical conditions. Here we focus on data acquired with the Research Scanning Polarimeter (RSP), which was mounted on the high-altitude ER-2 aircraft during SEAC4RS. RSP's unique multi-angular, multi-wavelength total and polarized reflectance measurements allow retrieval of ice effective radius, the aspect ratio of components of ice crystals, the crystal distortion level and ice asymmetry parameter, as well as cloud optical thickness and cloud top height. Using RSP data, as well as data from the eMAS and CPL sensors and in situ probes, we explore the statistical variation of ice properties retrieved during SEAC4RS in tops of convective systems. The data indicates that, in general, ice crystal populations consistent with plate-like components with aspect ratios near 0.4 are prevalent at cloud tops. The asymmetry parameter is around 0.76-0.8 and generally decreases with increasing cloud top height, mainly because the ice crystal distortion increases with height. Below about 12 km height, the effective radius decreases with increasing altitude, as previously shown for convective clouds using satellite data, but at higher levels the SEAC4RS data indicate a transition to effective radii increasing with cloud top height. Here we explore some possible explanations for this transition, related to its approximate coincidence with the level of minimum stability and the homogeneous freezing level, either of which could affect ice crystal formation and evolution. Additionally, we will demonstrate some of the

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Redelsperger, J. L.; Sommeria, G.

    1986-11-01

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

  19. 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.

  20. Improving the Knowledge of Summer Monsoon Storm Genesis on the Mumbai Region

    NASA Astrophysics Data System (ADS)

    Lomazzi, M.; Entekhabi, D.; Pinto, J. G.; Roth, G.; Rudari, R.

    2009-09-01

    Over the Indian Subcontinent, almost 75% of the annual precipitation is expected to fall during the South Asia Monsoon (SAM) season, conventionally defined between June 1 and September 30. While precipitation patterns show a very strong spatial heterogeneity, the maximum annual values (which may exceed 4000 mm) occur in the Western Coast of Indian Peninsula. This is mainly associated with orographic forcing, in particular of the Western Ghats and the Ganges and Brahmaputra valleys. Extreme rainfall events during the SAM season may be particularly intense and long-lasting, causing great damages both in terms of life and economic losses. We aim at identifying large-scale meteorological patterns associated with the triggering of extreme rainfall events affecting the Mumbai area (approximately 18-20°N, 72.5-73.5°E), a very highly populated region (around 20 million people), during the SAM season. Seventy years of daily rainfall data are analyzed and compared to a database of damage-causing precipitations. Event days are selected with a twin-threshold function related to daily rainfall height and soil moisture content. To detect typical large-scale features, event days are compared to non-event days by analyzing MSLP, SST, and vertical wind profiles. Further, the storm-related processes are analyzed with moisture sources (via backtracing) and moisture flux convergence fields. First results on selected event days show that they are typically characterized by remote moisture sources (from S-W Arabian Sea) and increased lower level westerly winds which cause enhanced moisture flux convergence, leading to precipitable water’s enhancement.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. Seasonal cycle of convective spells over southern Africa during austral summer

    NASA Astrophysics Data System (ADS)

    Makarau, Amos; Jury, Mark R.

    1997-10-01

    The seasonal progression of summer wet spells over southern Africa is investigated. The November to March rainy season is modulated at the intraseasonal scale, with major wet spells every 20-30 days and internal evolution at higher frequencies. Corresponding circulation patterns for each wet spell illustrate the variable dynamics and physics as the season progresses. Early summer rainfall is associated with enhanced baroclinic westerly shear from the upper troposphere of the tropical Atlantic Ocean, whereas low-level moisture is advected from the central Indian Ocean. Extratropical westerly wave action is an important influence during early summer. As the summer season progresses, heating causes a retreat of the subtropical westerly jet stream. A quasi-stationary line of confluence along 20°S develops in the low levels during late summer, and extends from the Mozambique Channel to Angola. This trough is supported by an influx of moisture from the Congo and southern Mozambique Channel. Composite differences between early and late summer wet spells are evaluated numerically for the first time in this presentation.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. 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

  9. North Equatorial Indian Ocean Convection and Indian Summer Monsoon June Progression: a Case Study of 2013 and 2014

    NASA Astrophysics Data System (ADS)

    Yadav, Ramesh Kumar; Singh, Bhupendra Bahadur

    2016-06-01

    The consecutive summer monsoons of 2013 and 2014 over the Indian subcontinent saw very contrasting onsets and progressions during the initial month. While the 2013 monsoon saw the timely onset and one of the fastest progressions during the recent decades, 2014 had a delayed onset and a slower progression phase. The monthly rainfall of June 2013 was +34 %, whereas in 2014 it was -43 % of its long-period average. The progress/onset of monsoon in June is influenced by large-scale circulation and local feedback processes. But, in 2013 (2014), one of the main reasons for the timely onset and fastest progression (delayed onset and slower progression) was the persistent strong (weak) convection over the north equatorial Indian Ocean during May. This resulted in a strong (weak) Hadley circulation with strong (weak) ascent and descent over the north equatorial Indian Ocean and the South Indian Ocean, respectively. The strong (weak) descent over the south Indian Ocean intensified (weakened) the Mascarene High, which in turn strengthened (weakened) the cross-equatorial flow and hence the monsoonal circulation.

  10. 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.

  11. Inter-comparison of deep convection over the Tibetan Plateau-Asian Monsoon Region and subtropical North America in boreal summer using CloudSat/CALIPSO data

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Deep convection at the Tibetan Plateau-Southern Asian Monsoon Region (TP-SAMR) is analyzed using CloudSat and CALIPSO data for the boreal summer season (June-August) from 2006 to 2009. Three sub-regions - the Tibetan Plateau (TP), southern slope of the Plateau (PSS), and southern Asian monsoon region (SAMR) - are defined and deep convection properties are compared among these sub-regions. To cast them in a broader context, we also bring in four additional regions that bear some similarity to the TP-SAMR: East Asia (EA), tropical northwestern Pacific (NWP), west and east North America (WNA, ENA). The principal findings are as follows: 1) Compared to the other two sub-regions of the TP-SAMR, deep convection at the TP is shallower, less frequent, and embedded in smaller-size convection systems, but the cloud tops are more densely packed. These characteristics of deep convection at the TP are closely related to the significantly lower level of neutral buoyancy (LNB) and much drier atmosphere. 2) In a broader context where all seven regions are brought together, deep convection at the two tropical regions (NWP and SAMR; mostly over ocean) is similar in many regards. Similar conclusion can be drawn among the four subtropical continental regions (TP, EA, WNA, and ENA). However, tropical oceanic and subtropical land regions present some significant contrasts: deep convection in the latter region occurs less frequently, has lower cloud tops but comparable or slightly higher tops of large radar echo, and is embedded in smaller systems. The cloud tops of the subtropical land regions are generally more densely packed. Hence, the difference between TP and SAMR is more of a general contrast between subtropical land regions and tropical oceanic regions during the boreal summer. 3) Deep convection at the PSS possesses some uniqueness of its own because of the distinctive terrain (slopes) and moist low-level monsoon flow. 4) Results from comparison between the daytime and the

  12. Intercomparison of Deep Convection over the Tibetan Plateau-Asian Monsoon Region and Subtropical North America in Boreal Summer Using CloudSat/CALIPSO Data

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Deep convection in the Tibetan Plateau-southern Asian monsoon region (TP-SAMR) is analyzed using CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data for the boreal summer season (June-August) from 2006 to 2009. Three subregions are defined—the TP, the southern slope of the plateau (PSS), and the SAMR—and deep convection properties (such as occurrence frequency, internal vertical structure, system size, and local environment) are compared among these subregions. To cast them in a broader context, four additional regions that bear some similarity to the TP-SAMR are also discussed: East Asia (EA), tropical northwestern Pacific (NWP), and western and eastern North America (WNA and ENA, respectively). The principal findings are as follows: 1) Compared to the other two subregions of the TP-SAMR, deep convection over the TP is shallower, less frequent, and embedded in smaller-size convection systems, but the cloud tops are more densely packed. These characteristics of deep convection over the TP are closely related to the unique local environment, namely, a significantly lower level of neutral buoyancy (LNB) and much drier atmosphere. 2) In a broader context in which all seven regions are brought together, deep convection in the two tropical regions (NWP and SAMR; mostly over ocean) is similar in many regards. A similar conclusion can be drawn among the four subtropical continental regions (TP, EA, WNA, and ENA). However, tropical oceanic and subtropical land regions present some significant contrasts: deep convection in the latter region occurs less frequently, has lower cloud tops but comparable or slightly higher tops of large radar echo (e.g., 0 and 10 dBZ), and is embedded in smaller systems. The cloud tops of the subtropical land regions are generally more densely packed.Hence, the difference between the TP and SAMRismore of a general contrast between subtropical land regions and tropical oceanic regions during the

  13. Simulation of Indian summer monsoon onset with different parameterization convection schemes of RegCM-4.3

    NASA Astrophysics Data System (ADS)

    Bhatla, R.; Ghosh, S.; Mandal, B.; Mall, R. K.; Sharma, Kuldeep

    2016-07-01

    Simulation of Indian Summer Monsoon (ISM) onset over South Asia Coordinated Regional Climate Downscaling Experiment (CORDEX) domain in pentad composite pattern is considered for this study. The latest version of the International Center for Theoretical Physics' (ICTP's) Regional Climate Model version 4.3 (RegCM-4.3) is used for the simulation of a pentad composite onset for three time period: Pre-onset, Onset and Post-onset periods of ISM. Each pentad composite is average of five consecutive days. 10 years (2001-2010) worth of pentad composites of rainfall, mean sea level pressure (MSLP), outgoing longwave radiation (OLR), wind at 850 hPa and 925 hPa levels till 7 days prior to the date of onset of monsoon and 7 days after the onset are analyzed to find out the predictive skill. Six Parameterization convection schemes (PCSs) viz. Kuo, Mix98, Mix99, Tiedtke, Emanuel and Grell are used in sensitivity experiment and estimation of their performance has been done. From the experiment, some modulation is found in the OLR field (≤ 200 Wm- 2) within the region 5°N-10°N and 70°N-75°E. Yearly analysis has shown the strength of wind at 925 hPa over the region 5°N-10°N and 70°E-80°E on pentad composite onset of ISM. Yearly analysis is conducted for finding the best fitted PCS which has provided the precursor for simulating the onset.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Ki, Mi-Ok; Chun, Hye-Yeong

    2011-08-01

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

  16. 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.

  17. 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.

  18. Thyroid storm

    MedlinePlus

    Thyrotoxic storm; Hyperthyroid storm; Accelerated hyperthyroidism; Thyroid crisis; Thyrotoxicosis - thyroid storm ... thyroid storm can be caused by treatment of hyperthyroidism with radioiodine therapy.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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 90°E. 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.

  4. 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.

  5. Role of convection in redistributing formaldehyde to the upper troposphere over North America and the North Atlantic during the summer 2004 INTEX campaign

    NASA Astrophysics Data System (ADS)

    Fried, Alan; Olson, Jennifer R.; Walega, James G.; 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.; Snow, Julie A.; Shen, Haiwei; O'Sullivan, Daniel W.; Brune, William H.; Ren, Xinrong; Blake, Donald R.; Blake, Nicola; Sachse, Glen; Diskin, Glenn S.; Podolske, James; Vay, Stephanie A.; Shetter, Richard E.; Hall, Samuel R.; Anderson, Bruce E.; Thornhill, Lee; Clarke, Antony D.; McNaughton, Cameron S.; Singh, Hanwant B.; Avery, Melody A.; Huey, Gregory; Kim, Saewung; Millet, Dylan B.

    2008-09-01

    Measurements of formaldehyde (CH2O) from a tunable diode laser absorption spectrometer (TDLAS) were acquired onboard the NASA DC-8 aircraft during the summer 2004 INTEX-NA campaign to test our understanding of convection and CH2O production mechanisms in the upper troposphere (UT, 6-12 km) over continental North America and the North Atlantic Ocean. The present study utilizes these TDLAS measurements and results from a box model to (1) establish sets of conditions by which to distinguish "background" UT CH2O levels from those perturbed by convection and other causes; (2) quantify the CH2O precursor budgets for both air mass types; (3) quantify the fraction of time that the UT CH2O measurements over North America and North Atlantic are perturbed during the summer of 2004; (4) provide estimates for the fraction of time that such perturbed CH2O levels are caused by direct convection of boundary layer CH2O and/or convection of CH2O precursors; (5) assess the ability of box models to reproduce the CH2O measurements; and (6) examine CH2O and HO2 relationships in the presence of enhanced NO. 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. 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 methyl hydroperoxide, methanol, PAN-type compounds, and ketones, in descending order of their contribution. At least 70% to 73% of the elevated UT observations were caused by enhanced production from CH2O precursors rather than direct transport of CH2O from the boundary layer. In the presence of elevated NO, there was a definite trend in the CH2O measurement-model discrepancy, and this was highly correlated with HO2 measurement-model discrepancies in the UT.

  6. The performance of land surface and cumulus convection scheme in the simulation of Indian Summer Monsoon using RegCM4

    NASA Astrophysics Data System (ADS)

    Maity, S.; Mandal, M.; Nayak, S.

    2015-12-01

    Indian Sumer Monsoon (ISM) is the most dominant tropical circulation process in the Atmospheric General Circulation System. It contributes about 70% of the total annual precipitation during June-September over India. Summer rainfall has substantial effect to the agriculture and economy of the country. ISM is dominated by convection and land surface processes also play important role through transfer of energy and moisture. These processes must be well represented in the numerical models for better simulation of ISM. Therefore it is important to investigate the performance of various land surface and cumulus schemes in simulating ISM. In this study, performance of the convection and land surface schemes in simulating ISM are investigated using RegCM 4. The performance of two land surface schemes [BATS, CLM 3.5] and five convection schemes [MIT, Kuo, Grell, Grell over Land and MIT over Ocean (GL_MO), Grell over Ocean and MIT over Land (GO_ML)] are tested. The model at 30 km resolution covering (30˚E-120˚E, 15˚S-45˚N) is integrated for the period of 1st May-30thSeptember during 2007, 2008 and 2009. The initial and boundary conditions are derived from NNRP1 data at 2.5˚×2.5˚ resolution. The Sea Surface Temperature is taken from NOAA Optimum Interpolation weekly mean data at 1˚×1˚ resolution. Some important features of ISM simulated by the model; viz. Somaly jet, Tropical easterly jet (TEJ), Heat low, Tibetan high etc. are analyzed with NCEP reanalysis. Heat low is well produced by the model with MIT, GO_ML and GL_MO schemes. The Somaly jet is usually weak but better simulated with MIT scheme. Although the model is able to reproduce the TEJ and Subtropical westerly jet, the location and strength of the jets are varying scheme-wise and is better simulated by MIT scheme. The model is also able to simulate the stronger easterly jet in 2007 compared to 2009 with MIT scheme. The rainfall over Central and North West India is significantly under-predicted by the

  7. 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.

  8. Calibration of a convective parameterization scheme in the WRF model and its impact on the simulation of East Asian summer monsoon precipitation

    NASA Astrophysics Data System (ADS)

    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.

  9. 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

    2014-03-26

    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. Lastly, 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

  10. 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

    2014-03-26

    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. Lastly, 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.

  11. 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

  12. 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.

  13. Mechanisms underlying the cooling observed within the TTL during the active spells of organized deep convection of the Indian Summer Monsoon with COSMC RO and In-situ Measurements

    NASA Astrophysics Data System (ADS)

    Rao, Kusuma; Reddy, Narendra

    Climate impact of the Asian monsoon as a tropical phenomena has been studied for decades in the past for its tropospheric component. However, the effort towards assessing the role of the Asian summer monsoon in the climate system with focus on the Upper Troposphere into the Lower Stratosphere (UTLS) is being addressed only in the recent times. Deep convective vertical fluxes of water and other chemical species penetrate and ventilate the TTL for redistribution of species in to stratosphere. However, the mechanisms underlying such convective transports are yet to be understood. Our specific goal here is to investigate the impact of organized deep moist convection of the Indian summer monsoon on thermal structure of UTLS, and to understand the underlying mechanisms. Since active monsoon spells are manifestations of organized deep convection embedded with overshooting convective elements, it becomes absolutely imperative to understand the impact of organized monsoon convection on three time scales, namely, (i) super synoptic scales of convectively intense active monsoon spells, (ii) on synoptic time scales of convectively disturbed conditions, and finally on (iii) cloud scales. Impact of deep convection on UTLS processes is examined here based on analysis of COSMIC RO and the METEOSAT data for the period, 2006-2011 and the in-situ measurements available from the national programme, PRWONAM during 2009-10 over the Indian land region and from the International field programme, JASMINE during 1999 over the Bay of Bengal. On all the three time scales during (i) the active monsoon spells, (ii) the disturbed periods and (iii) during the passage of deep core of MCSs, we inferred that the Coldpoint Tropopause Temperatures (CPT) lower at relatively lower CPT Altitudes (CPTA) unlike in the cases determined by normal temperature lapse rates; these unusual cases are described here as ‘Unlike Normal’ cases. TTL thickness shrinks during the convective conditions. During the

  14. 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.

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  18. 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.

  19. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    article title:  Massive Dust Storm over Australia     View ... at JPL September 22, 2009 - Massive dust storm over Australia. project:  MISR category:  ... Sep 22, 2009 Images:  Dust Storm location:  Australia and New Zealand ...

  20. Development of lidar sensor for cloud-based measurements during convective conditions

    NASA Astrophysics Data System (ADS)

    Vishnu, R.; Bhavani Kumar, Y.; Rao, T. Narayana; Nair, Anish Kumar M.; Jayaraman, A.

    2016-05-01

    Atmospheric convection is a natural phenomena associated with heat transport. Convection is strong during daylight periods and rigorous in summer months. Severe ground heating associated with strong winds experienced during these periods. Tropics are considered as the source regions for strong convection. Formation of thunder storm clouds is common during this period. Location of cloud base and its associated dynamics is important to understand the influence of convection on the atmosphere. Lidars are sensitive to Mie scattering and are the suitable instruments for locating clouds in the atmosphere than instruments utilizing the radio frequency spectrum. Thunder storm clouds are composed of hydrometers and strongly scatter the laser light. Recently, a lidar technique was developed at National Atmospheric Research Laboratory (NARL), a Department of Space (DOS) unit, located at Gadanki near Tirupati. The lidar technique employs slant path operation and provides high resolution measurements on cloud base location in real-time. The laser based remote sensing technique allows measurement of atmosphere for every second at 7.5 m range resolution. The high resolution data permits assessment of updrafts at the cloud base. The lidar also provides real-time convective boundary layer height using aerosols as the tracers of atmospheric dynamics. The developed lidar sensor is planned for up-gradation with scanning facility to understand the cloud dynamics in the spatial direction. In this presentation, we present the lidar sensor technology and utilization of its technology for high resolution cloud base measurements during convective conditions over lidar site, Gadanki.

  1. Rainfall Climatology of the US Based on a Multifractal Storm Model

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Whether the multifractal properties of rainfall are impacted by climatology and therefore deviate from universality is a vexing question in both hydrology and the climate sciences and a crucial issue for rainfall downscaling applications. In a recent paper, Veneziano and Lepore (The Scaling of Temporal Rainfall, WRR, 2012) suggested a rainfall model with alternating storms and dry inter-storm periods and beta-lognormal multifractal rainfall intensity inside the storms. The parameters of the model are the rate of storm arrivals λ , the mean value mD and coefficient of variation VD of storm duration, the mean rainfall intensity inside the storms mI, and the multifractal parameters Cβ (lacunarity), CLN (intermittency), and dmax (outer limit of the scaling range). We use this model and 200 hourly rainfall records from NOAA to describe the variability of intense rainfall over the continental US. The records are selected based on length (at least 25 years) and data quality (quantization, fraction of unavailable values, periods when rainfall is reported as aggregated total depth…). We conclude that CLN and dmax display large systematic variations in space and with season. In particular, CLN decreases as latitude increases, from 0.20-0.25 along the Gulf of Mexico to about 0.12 in New England and 0.08 in the Northwest. This spatial variation is captured in approximation by partitioning the continental US into 11 climatic regions. Seasonal analysis shows that in most regions CLN is highest in the summer and lowest in the winter, following similar variations in the frequency and intensity of convective rainfall. An exception is the Northwest region, where CLN is almost constant throughout the year. The outer scale dmax is negatively correlated with CLN and follows opposite trends. The lacunarity parameter Cβ is lowest (around 0.04) in the Northeast and highest (around 0.07) in Florida and the Midwestern region. Lacunarity tends to be higher in the spring and summer

  2. 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

  3. August 28, 1978, Storm 1. GEOS 2 observations of the initial magnetopause crossings and STARE observations near the ionospheric convection reversal

    SciTech Connect

    Sofko, G.J.; Korth, A.; Kremser, G.

    1985-02-01

    During the postdawn period on August 28, 1978, from approx.0750 to 0830 magnetic local time, the magnetopause moved several earth radii inward to less than 6.6 R/sub E/, where it remained until approx.1120 MLT. As the magnetopause approached the earth, the poleward boundary of the westward auroral electrojet moved southward to geomagnetic latitudes less than 66/sup 0/. Fortuitously, the geostationary satellite GEOS 2 was located in this morning sector during this entire period, and experienced a series of magnetopause crossings. In quiet periods GEOS 2 was conjugate to that area of the lower E region which constituted the field-of-view of the Scandinavian Twin Auroral Radar Experiment (STARE) radars. This paper compares the magnetospheric satellite and ionospheric radar observations. The combined observations suggest that, near the dawnside magnetopause, large-scale merging was occurring, while in the ionosphere, the convection reversal region and poleward portion of the auroral zone underwent major equatorward shifts and featured prominent sunward moving ULF pulsations. Between the magnetopause and ionosphere a large increase in the ring current accompanied the equatorward shift of the convection reversal.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. How can anomalous western North Pacific Subtropical High intensify in late summer?

    NASA Astrophysics Data System (ADS)

    Xiang, Baoqiang; Wang, Bin; Yu, Weidong; Xu, Shibin

    2013-05-01

    The western North Pacific (WNP) Subtropical High (WNPSH) is a controlling system for East Asian Summer monsoon and tropical storm activities, whereas what maintains the anomalous summertime WNPSH has been a long-standing riddle. Here we demonstrate that the local convection-wind-evaporation-SST (CWES) feedback relying on both mean flows and mean precipitation is key in maintaining the WNPSH, while the remote forcing from the development of the El Niño/Southern Oscillation is secondary. Strikingly, the majority of strong WNPSH cases exhibit anomalous intensification in late summer (August), which is dominantly determined by the seasonal march of the mean state. That is, enhanced mean precipitation associated with strong WNP monsoon trough in late summer makes atmospheric response much more sensitive to local SST forcing than early summer.

  10. Magnetic Storms

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  11. 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.

  12. Deep convection in mesoscale convective systems

    NASA Technical Reports Server (NTRS)

    Goodman, S. J.

    1985-01-01

    A study was undertaken to examine the evolution of radar echoes and lightning attending the convective storms in mesoscale convective systems (MCS) and the relationships between the spatial and temporal evolution of deep convection and the storm environment, precipitation, severe weather, and lightning. The total number of ground discharges ranges from 10,000 to 30,000 over the life cycle of the MCS with peak sustained rates (for up to 10 consecutive hours) in excess of 2000 per hour. The peak lightning activity occurs from 5 to 20 hours after the first storms and anywhere from 7 hours prior to 7 hours after the time of the maximum areal extent of the MCS for very similar synoptic environments. Thus, it appears that mesoscale and sub-synoptic scale mechanisms are responsible for these large temporal variation in lightning activity. In addition, we have found that the lightning rates in MCS's are not related to either the size or the duration of the MCS. Preliminary results suggest that the MCA's with embedded squall lines produce the greatest flash rates.

  13. 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.

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

    PubMed

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

    2005-06-01

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

  15. Interaction Between Two Distinct Mesoscale Circulations During Summer in the Coastal Region of Eastern USA

    NASA Astrophysics Data System (ADS)

    Sims, Aaron P.; Raman, Sethu

    2016-07-01

    The interaction of two phenomena, a sea-breeze front and a thermally-driven local circulation, is investigated during the summer season. The sea-breeze circulation in the coastal Carolinas (USA) can be quite strong and the sea-breeze front often propagates well inland. The Sandhills, an area of sandy soils, is oriented roughly parallel to the coast and is located approximately 180 km inland. Differential heating is a strong driving force for convective development in this coastal region and the Sandhills front develops from the thermally-driven circulation caused by the differential heating of differing soil types. The sea-breeze and the Sandhills circulations have been previously studied independently, however, the interaction of these two phenomena is not well known. A combination of remote sensing, in situ observations, and numerical simulations is used to examine the interaction of these two fronts with remote sensing and in situ observations revealing the differential heating that occurs along the Sandhills region. Radar reflectivity is used to identify the two frontal features that converge and result in enhanced convection. A modelling simulation reveals the vertical structure of the frontal features, their propagation, and interaction, highlighting the interaction of the two fronts that results in enhanced convection between the Sandhills and the coast. Over the Sandhills region, differential heating triggers convective storms. Radar reflectivity and numerical simulation indicate the outflows from these convective storms to produce a shallow Sandhills front that in turn propagates toward the coast. As the two opposing fronts, the Sandhills front and the sea-breeze front, converge and interact, intense convection occurs resulting in additional storms.

  16. Interaction Between Two Distinct Mesoscale Circulations During Summer in the Coastal Region of Eastern USA

    NASA Astrophysics Data System (ADS)

    Sims, Aaron P.; Raman, Sethu

    2016-01-01

    The interaction of two phenomena, a sea-breeze front and a thermally-driven local circulation, is investigated during the summer season. The sea-breeze circulation in the coastal Carolinas (USA) can be quite strong and the sea-breeze front often propagates well inland. The Sandhills, an area of sandy soils, is oriented roughly parallel to the coast and is located approximately 180 km inland. Differential heating is a strong driving force for convective development in this coastal region and the Sandhills front develops from the thermally-driven circulation caused by the differential heating of differing soil types. The sea-breeze and the Sandhills circulations have been previously studied independently, however, the interaction of these two phenomena is not well known. A combination of remote sensing, in situ observations, and numerical simulations is used to examine the interaction of these two fronts with remote sensing and in situ observations revealing the differential heating that occurs along the Sandhills region. Radar reflectivity is used to identify the two frontal features that converge and result in enhanced convection. A modelling simulation reveals the vertical structure of the frontal features, their propagation, and interaction, highlighting the interaction of the two fronts that results in enhanced convection between the Sandhills and the coast. Over the Sandhills region, differential heating triggers convective storms. Radar reflectivity and numerical simulation indicate the outflows from these convective storms to produce a shallow Sandhills front that in turn propagates toward the coast. As the two opposing fronts, the Sandhills front and the sea-breeze front, converge and interact, intense convection occurs resulting in additional storms.

  17. NASA's GPM Gets a Look at Newborn, Late Season Eastern Pacific Tropical Storm Sandra

    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 ...

  18. 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.

  19. A Giant Storm in Saturn's Northern Hemisphere

    NASA Astrophysics Data System (ADS)

    Kurth, W. S.; Fischer, G.; Gurnett, D. A.; Zarka, P. M.; Dyudina, U. A.; Ingersoll, A. P.; Ewald, S. P.; Porco, C.; Wesley, A.; Go, C.; Delcroix, M.

    2011-12-01

    Beginning on December 5, 2010, an extraordinary thunderstorm developed as observed via the radio signatures of lightning using the Radio and Plasma Wave Science (RPWS) instrument and the appearance of a convective cloud in Cassini's Imaging Science System (ISS) images. These instruments as well as amateur astronomers across the globe have continued to track this storm to the present. The storm is extraordinary in that it is the first observed by Cassini in the northern hemisphere near 35 degrees planetocentric north latitude and is, by far, the largest storm observed by Cassini during its mission at Saturn and is comparable to the Great White Spot (GWS) storms observed approximately once per Saturn year. The development from the barely visible indications on December 5 to a storm of GWS status occurred over about 3 weeks. Expansion of the storm in latitude within a latitudinal gradient in the wind system of the planet resulted in an elongated eastward tail which entirely circled the planet by February 2011. The primary active cell lies in a relatively localized area around the main plume of high altitude clouds that overshoot the ammonia cloud layer due to strong vertical convection, although other, weaker cells occasionally develop within the tail. The lightning flash rate of this storm peaked at an order of magnitude higher than previously recorded storms with strokes occurring at the rate of 10 per second and the total power estimated for the storm is comparable to Saturn's total emitted power, making it a significant element of the planet's energy budget. That this storm occurred a year or so after northern vernal equinox suggests a seasonal change in the location of Saturn's thunderstorms. We will summarize observations of this extraordinary storm and update its progress as it is ongoing at the time of this writing.

  20. Tropical Storm Erin

    NASA Technical Reports Server (NTRS)

    2007-01-01

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

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

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

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

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

  1. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    ... contrast strongly with the dust storm that swept across Iraq and Saudi Arabia on May 13, 2004 (bottom panels). These data products from ... as yellowish ripples that obscure a large part of southern Iraq. The dust is easy to discern over the dark waters of the teardrop-shaped ...

  2. 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.

  3. 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

  4. 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

  5. Comparing and Linking Post-fire Hillslope Erosion and Channel Change for Different Storm Types

    NASA Astrophysics Data System (ADS)

    MacDonald, Lee; Kampf, Stephanie; Brogan, Dan; Schmeer, Sarah; Nelson, Peter

    2016-04-01

    Moderate and high severity wildfires can greatly reduce infiltration rates, leading to orders of magnitude increases in hillslope-scale runoff and erosion rates. These increases can cause dramatic downstream channel change, with post-fire deposition being most common, but this depends on the number, magnitude and timing of storm events. The objective of this study is to compare post-fire hillslope erosion rates and downstream channel change from two distinct rainfall events approximately one year after burning. The first was a set of relatively typical, higher-intensity convective storms in June-August 2013, and the second was a highly unusual, week-long ~270 mm rainstorm in September 2013. The study was conducted in two ~15 km2 watersheds that had two-thirds of their area burned at high or moderate severity by 2012 High Park Fire in northcentral Colorado, USA. Hillslope erosion was measured with sediment fences at 29 sites grouped into five clusters, with each cluster having an associated tipping bucket rain gage. Downstream channel change was monitored at approximately ten cross-sections in each of the two watersheds, Skin Gulch and Hill Gulch. Twelve summer storms produced an overall mean hillslope erosion of 6 Mg ha-1, with higher rainfall intensities at lower elevations and in Skin Gulch causing higher sediment yields. The higher sediment yields in Skin Gulch caused substantial downstream deposition of up to 0.8 m at most cross-sections. Generally lower rainfall in Hill Gulch resulted in less Horton overland flow and hence lower erosion rates and much less downstream deposition. The September storm had roughly twice as much rainfall as the summer thunderstorms, but there were much lower peak rainfall intensities and hillslope-scale sediment yields except where shallow bedrock induced saturation overland flow. The much longer duration of the September storm resulted in sustained high flows, and these flows plus the lower hillslope erosion caused most of the

  6. 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 %.

  7. 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

  8. 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.

  9. Global distribution of deep convection reaching tropopause in 1 year GPM observations

    NASA Astrophysics Data System (ADS)

    Liu, Nana; Liu, Chuntao

    2016-04-01

    To characterize and quantify tropopause-reaching deep convection, 1 year of Global Precipitation Mission (GPM) Ku band radar echoes are surveyed in relation to several reference levels derived from the ERA-Interim reanalysis data set. Consistent with the observations of the Tropical Rainfall Measuring Mission over the tropics, the GPM has detected tropopause-reaching deep convection dominantly over tropical land, especially over Panama and Central Africa. At middle and high latitudes, tropopause-reaching convective storms are mainly found over land in the Northern Hemisphere during the summer. Compared to those in the tropics, convective cores at middle and high latitudes have relatively larger sizes at the tropopause, especially those over central North America. The zonal distributions of the occurrences of 15 dBZ and 20 dBZ radar echoes at the tropopause show two comparable maxima, one in the tropics and the other in northern middle-high latitudes. This implies that the convection penetrating the tropopause at northern middle-high latitudes is as frequent as those over the tropics. It is important to understand their role in the vertical transport of trace gases between the troposphere and the stratosphere.

  10. 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.

  11. Contrasting ice microphysical properties of wintertime frontal clouds and summertime convective clouds

    NASA Astrophysics Data System (ADS)

    Wu, W.; McFarquhar, G. M.

    2015-12-01

    The microphysical and optical properties of ice clouds were derived from measurements collected during the Colorado Airborne Multi-phase Cloud Study (CAMPS) and the Storm Peak Laboratory Cloud Property Validation Experiment (STORMVEX) conducted in the winter of 2010-2011 over the Rocky Mountains and during the Midlatitude Continental Convective Clouds Experiment (MC3E) conducted in the summer of 2011 over Oklahoma. A two-dimensional cloud (2DC) probe, two-dimensional precipitation (2DP) probe and Fast 2DC probe were installed on the University of Wyoming King Air aircraft during CAMPS and a Cloud Imaging Probe (CIP) and Precipitation Imaging Probe were operated on the ground at the Storm Peak Laboratory during STORMVEX. A 2DC, CIP and a high volume precipitation spectrometer were installed in the University of North Dakota Citation aircraft during MC3E. The distributions of particle habits, number distribution functions, total number concentrations, ice water contents, precipitation rates, extinction and effective radius from four cases of wintertime frontal clouds sampled during CAMPS/STORMVEX and from four cases of the stratiform region of summer convective systems from MC3E are compared. It is found that there is higher percentage of pristine ice particles, such as dendrites and columns, in the wintertime frontal clouds than in the summertime convective clouds, where the dominant habits are rimed particles. The number distribution functions are generally broader in the summertime clouds than in the wintertime frontal clouds. In addition, the number concentrations and ice water contents are generally lower in the wintertime frontal clouds than in the summertime convective clouds when comparing the same temperature ranges. Implications about the potential microphysical processes that are acting in these two types of ice clouds are discussed. The results in this study are also compared with previous studies using data from other field campaigns.

  12. 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

    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.

  13. 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

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

    NASA Astrophysics Data System (ADS)

    shalaby, ahmed

    2014-05-01

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

  15. 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

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

    NASA Astrophysics Data System (ADS)

    Hueso, Ricardo; Sánchez-Lavega, A.

    2006-09-01

    Under the pressure-temperature conditions on Titan, methane, a large atmospheric component amounting perhaps to a 3-5% of the atmosphere, is close to its triple point, potentially playing a similar role as water on Earth. The Huygens probe and Cassini radar images have shown a terrain shaped by erosion of probably liquid origin, suggestive of past rain. On the other hand, Voyager IRIS spectroscopic observations of Titan indicate that methane saturation occurs amounting perhaps to 150%, suggesting that the satellite should regularly be covered by methane clouds. Telescopic observations from the Earth and Cassini have shown that clouds are localized, transient and fast evolving, in particular in the South Polar Region (currently in its summer season until its autumn equinox in 2008). To explain these observations, we investigate different scenarios of moist convective storms on Titan using a three-dimensional cloud resolving model that incorporates microphysics and allows computing the precipitation that reaches the surface as a function of the concentration of cloud condensation nuclei in the atmosphere. We show that under the appropriate conditions, precipitation rates comparable to intense tropical storms on Earth could take place. A typical storm may form when the methane humidity is on the order of 80%, developing vertical velocities of 20 ms-1 with the updrafts reaching up to 30 km height during a total life-span of a few hours, producing maximum precipitation rates of 100 kgm-2, that are comparable to flash-floods on Earth. Acknowledgements: This work has been funded by Spanish MCYT PNAYA2003-03216, fondos FEDER and Grupos UPV 15946/2004. R. Hueso acknowledges an RyC research contract form the Spanish MEC.

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    SciTech Connect

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

    1998-08-01

    the storm-time ring current. An apparently new controversy regarding the relative importance of the two processes is thus created. It is important to identify the role of substorm occurrence in the large-scale enhancement of magnetospheric convection driven by solar wind electric fields. (3) Numerical schemes for predicting geomagnetic activity indices on the basis of solar/solar wind/interplanetary magnetic field parameters continue to be upgraded, ensuring reliable techniques for forecasting magnetic storms under real-time conditions. There is a need to evaluate the prediction capability of geomagnetic indices on the basis of physical processes that occur during storm time substorms. (4) It is crucial to differentiate between storms and nonstorm time substorms in terms of energy transfer/conversion processes, i.e., mechanical energy from the solar wind, electromagnetic energy in the magnetotail, and again, mechanical energy of particles in the plasma sheet, ring current, and aurora. To help answer the question of the role of substorms in energizing ring current particles, it is crucial to find efficient magnetospheric processes that heat ions up to some minimal energies so that they can have an effect on the strength of the storm time ring current. (5) The question of whether the {ital Dst} index is an accurate and effective measure of the storm time ring-current is also controversial. In particular, it is demonstrated that the dipolarization effect associated with substorm expansion acts to reduce the {ital Dst} magnitude, even though the ring current may still be growing. {copyright} 1998 American Geophysical Union

  19. 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.

  20. In Brief: Cassini images Saturn storm

    NASA Astrophysics Data System (ADS)

    Zielinski, Sarah

    2006-11-01

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

  1. 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

  2. Severe convection features in the Amazon Basin: a TRMM-based 15-year evaluation

    NASA Astrophysics Data System (ADS)

    Pereira Nunes, Ana; Silva Dias, Maria; Anselmo, Evandro; Rodriguez, Carlos

    2016-04-01

    Rainfall in the Amazon Basin is very heterogeneous, mainly because the area encompassed is quite large. Among the systems responsible for rainfall, some stand out as extreme storm events. This study presents a criterion for identifying potentially severe convection in the Amazon region from the Tropical Rainfall Measuring Mission (TRMM) database, specifically from Precipitation Features (PF) - 1998-2012 - generated and stored by the University of Utah. The seasonal and spatial distributions are similar to distributions of Mesoscale Convective Systems already catalogued in previous studies based on GOES satellite images. The seasons with the highest number of cases are austral spring, winter, and fall. With the Amazon region divided into six subregions and cases accumulated by quarter (JFM, AMJ, JAS, OND) the south of the Amazon subregion (SA) accounts for the largest number of cases with the OND quarter with higher occurrence and the lowest in AMJ. Different diurnal cycles of potentially severe convection are observed across the region with the more western areas, closer to the Andes, favoring nighttime cases, especially in the austral spring and summer. The diurnal cycle of the number of the most extreme cases is more pronounced than the diurnal cycle when a large collection of deep convection cases are included.

  3. 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.

  4. 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.

  5. 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.

  6. Using satellite data to aid in diagnosing and forecasting convective development and intensity along arc cloud lines

    NASA Technical Reports Server (NTRS)

    Purdom, James F. W.; Sinclair, Peter C.

    1988-01-01

    The convective scale interactions associated with the arc cloud line are studied using GOES data. Studies of convective scale interactions are reviewed and the convective scale interaction phenomena is described. The use of satellite data in nowcasting and forecasting convective storms is discussed.

  7. 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

  8. 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

  9. 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.

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

    USGS Publications Warehouse

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

    1998-01-01

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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Tropical Storm Bud

    Atmospheric Science Data Center

    2013-04-19

    article title:  A Strengthening Eastern Pacific Storm     View Larger Image ... Imaging SpectroRadiometer (MISR) show then Tropical Storm Bud as it was intensifying toward hurricane status, which it acquired ...

  17. Summer Learners.

    ERIC Educational Resources Information Center

    Harrington-Lueker, Donna

    2000-01-01

    Many urban districts are sending thousands of poorly performing students to summer school to boost achievement. Boston, New York City, and other districts are finding summer school a costly, complicated intervention that does not always show immediate results or resolve social-promotion problems. Implementation strategies are outlined. (MLH)

  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. 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%.

  20. 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

  1. Test and evaluation plan for the Centralized Storm Information System

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The installation of the Centralized Storm Information System (CSIS) at the NOAA operational complex in Kansas City, Missouri is described. This complex includes the National Severe Storms Forecast center and a Satellite Field Service Station which is denoted in this research plan as NSSFC. CSIS computers will act in concert to merge analyze the many data sets needed to forecast severe convective storms. Specific aspects of CSIS are evaluated against the CSIS objectives. The functions to be evaluated characterize the attributes of a generalized interactive computer system. A major development in the CSIS program will allow communication between CSIS and the NSSFC Eclipse computer.

  2. 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.

  3. Interannual similarity in the Martian atmosphere during the dust storm season

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    We find that during the dusty season on Mars (southern spring and summer) of years without a global dust storm there are three large regional-scale dust storms. The storms are labeled A, B, and C in seasonal order. This classification is based on examining the zonal mean 50 Pa (˜25 km) daytime temperature retrievals from TES/MGS and MCS/MRO over 6 Mars Years. Regional-scale storms are defined as events where the temperature exceeds 200 K. Examining the MCS dust field at 50 Pa indicates that warming in the Southern Hemisphere is dominated by direct heating, while northern high latitude warming is a dynamical response. A storms are springtime planet encircling Southern Hemisphere events. B storms are southern polar events that begin near perihelion and last through the solstice. C storms are southern summertime events starting well after the end of the B storm. C storms show the most interannual variability.

  4. 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.

  5. Utilities weather the storm

    SciTech Connect

    Lihach, N.

    1984-11-01

    Utilities must restore power to storm-damaged transmission and distribution systems, even if it means going out in ice storms or during lightning and hurricane conditions. Weather forecasting helps utilities plan for possible damage as well as alerting them to long-term trends. Storm planning includes having trained repair personnel available and adjusting the system so that less power imports are needed. Storm damage response requires teamwork and cooperation between utilities. Utilities can strengthen equipment in storm-prone or vulnerable areas, but good data are necessary to document the incidence of lighning strikes, hurricanes, etc. 2 references, 8 figures.

  6. Climatological characteristics of deep and shallow precipitation clouds in summer over the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Pan, Xiao; Fu, Yunfei

    2016-04-01

    The Tibetan Plateau (TP) is the highest plateau with complex terrain in the world, and it can affect the weather and climate of many regions through its mechanical and thermal effects. The precipitation types over TP are divided into deep (strong deep convection and weak deep convection) and shallow precipitations, according to the particular atmospheric vertical structures of TP. The climatological characteristics of the deep and shallow precipitations including their horizontal distributions, infrared signal characteristics of clouds, vertical structures, diurnal variations and local phase shifts over TP are investigated by utilizing combining measurements of the tropical rainfall measuring mission (TRMM) precipitation radar (PR) and visible and infrared scanner (VIRS) in summer from 1998 to 2007. The results show that the precipitation over TP is mainly in the form of weak deep convection, which occupies 67.8% of total rain, then followed by shallow precipitation with 26.4% and the strong deep convection with 5.8%. The clouds for strong deep convection and weak deep convection are mainly composed of ice and ice-water mixed particles, respectively. The vertical profiles of deep precipitations firstly increase, and then decrease from the storm top altitude to the ground level, with maximizing at about 7.5 km altitude. In contrast, the vertical profile of the shallow precipitation only has an increasing process. The deep precipitations have significant diurnal variations. The precipitation frequencies for strong deep convection and weak deep convection both peak at 16 local time (LT), while the rain intensities for them peak at 13 and 18 LST, respectively. Furthermore, the rain intensity for strong deep convection is characterized by a secondary peak at 00 LT. For the shallow precipitation, the diurnal variation is relatively weaker. The precipitation frequency and intensity both peak at 20 LT, presenting the characteristic of night rain. The diurnal variations of

  7. Spectral characteristics of mid-latitude continental convection from a global variable-resolution Voronoi-mesh atmospheric model

    NASA Astrophysics Data System (ADS)

    Wong, M.; Skamarock, W. C.

    2015-12-01

    Global numerical weather forecast tests were performed using the global nonhydrostatic atmospheric model, Model for Prediction Across Scales (MPAS), for the NOAA Storm Prediction Center 2015 Spring Forecast Experiment (May 2015) and the Plains Elevated Convection at Night (PECAN) field campaign (June to mid-July 2015). These two sets of forecasts were performed on 50-to-3 km and 15-to-3 km smoothly-varying horizontal meshes, respectively. Both variable-resolution meshes have nominal convection-permitting 3-km grid spacing over the entire continental US. Here we evaluate the limited-area (vs. global) spectra from these NWP simulations. We will show the simulated spectral characteristics of total kinetic energy, vertical velocity variance, and precipitation during these spring and summer periods when diurnal continental convection is most active over central US. Spectral characteristics of a high-resolution global 3-km simulation (essentially no nesting) from the 20 May 2013 Moore, OK tornado case are also shown. These characteristics include spectral scaling, shape, and anisotropy, as well as the effective resolution of continental convection representation in MPAS.

  8. 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.

  9. Mesoscale Convective Systems Which Do and Do Not Produce Sprites: Results From STEPS 2000

    NASA Astrophysics Data System (ADS)

    Lyons, W. A.; Andersen, L. M.; Nelson, T. E.; Cummer, S. A.; Jauget, N. C.; Huffines, G. R.

    2005-12-01

    During the Severe Thunderstorm Electrification and Precipitation Study (STEPS) conducted during the summer of 2000 over the High Plains, we addressed two basic questions. First, what are the characteristics of those positive cloud-to-ground strokes (+CGs) which produce transient luminous events (TLEs), especially sprites, halos and elves? It was found the vast majority TLEs optically confirmed over High Plains storms were associated with large charge moment change events (DMq), exceeding thresholds of several hundred C km, substantially larger than the DMq for "normal" lightning. This finding is entirely consistent with present theoretical models of sprite ignition at ~75 km due to conventional breakdown. The second question addressed concerned what types of storms produced these unusual CG discharges. Not all mesoscale convective systems (MCSs) produce TLEs, or if they do, do so only for certain stages in their life cycle. Why? Meteorological analyses of TLE-producing systems had determined that the TLE parent +CGs were concentrated mostly in the stratiform region of their parent storms. Initial and updated analyses for Lightning Mapping Array data from the New Mexico Tech system suggested that the majority of the charge in the parent +CGs was removed from relatively low altitudes in the storm, typically 3 to 5 km AGL. After summarizing the characteristics of over 1500 TLEs and their parent MCSs, some clear criteria have become evident. First the cloud top canopy must be larger than 20,000 sq. km at the 50C level, and the coldest temperature must be at least -55C. Second, the peak reflectivity somewhere in the parent storm must exceed 55 dBZ. This requirement for a very tall and also intense storm initially seems at odds with the known environment of TLE parent CGs (low in the startiform region). Yet, as will be discussed, the emerging conceptual models of TLEs within trailing stratiform regions suggests the overall picture is indeed consistent with what is known

  10. 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.

  11. Beaufort Sea storm and resuspension modeling

    NASA Astrophysics Data System (ADS)

    Lintern, D. Gwyn; Macdonald, Robie W.; Solomon, Steven M.; Jakes, Hunter

    2013-11-01

    Along the shallow Beaufort Sea coast of the Arctic Ocean, storm events during the summer are responsible for significant sediment resuspension and transport. Given the paucity of data in this difficult field area, a model has been developed to be used as a tool towards investigation of these processes. Two contrasting set of conditions are modeled; one simulation for a relatively quiescent period and a second simulation for a period that included a moderate and typical northwesterly storm. Results for these two periods are compared with shallow-water current and wave data collected by instrumented moorings. For the calm period, the model did not predict specific events very well, whereas for the period with a strong storm, the model performed very well in predicting wave height and wave period, and less well in predicting currents. However, under both calm and stormy conditions, mean current speeds and mean current directions were predicted with sufficient accuracy to proceed to calculations of sediment transport. Sensitivity analysis showed that currents contribute very little to the wave dominated resuspension, but mean currents could be used for computing sediment transport quantities and directions. Measurements of storm surge were represented well by the model output, aligning perfecting with the building and waning storm, but with a slight overprediction at the peak of the storm. The reasonable reproduction of wave heights and periods, and of storm surge indicate that the model is responding well to the input parameters. The modeling suggests that the most significant sediment erosion occurs at the northern tips of the Mackenzie Delta and the Tuktoyaktuk Peninsula, and around the area of Herschal Island. The model also indicates that waves are not fully developed during a storm for the present day ice limited fetch, and that extending the fetch a further 100 km to simulate ice retreat led to wave heights at the coast being increased by 20 cm.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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…

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Long-Lived Storms and Squall Lines on Titan

    NASA Astrophysics Data System (ADS)

    Rafkin, S. C.; Barth, E. L.

    2015-12-01

    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 1a). 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 1b). 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.

  2. Factors Associated With Mortality of Thyroid Storm

    PubMed Central

    Ono, Yosuke; Ono, Sachiko; Yasunaga, Hideo; Matsui, Hiroki; Fushimi, Kiyohide; Tanaka, Yuji

    2016-01-01

    Abstract Thyroid storm is a life-threatening and emergent manifestation of thyrotoxicosis. However, predictive features associated with fatal outcomes in this crisis have not been clearly defined because of its rarity. The objective of this study was to investigate the associations of patient characteristics, treatments, and comorbidities with in-hospital mortality. We conducted a retrospective observational study of patients diagnosed with thyroid storm using a national inpatient database in Japan from April 1, 2011 to March 31, 2014. Of approximately 21 million inpatients in the database, we identified 1324 patients diagnosed with thyroid storm. The mean (standard deviation) age was 47 (18) years, and 943 (71.3%) patients were female. The overall in-hospital mortality was 10.1%. The number of patients was highest in the summer season. The most common comorbidity at admission was cardiovascular diseases (46.6%). Multivariable logistic regression analyses showed that higher mortality was significantly associated with older age (≥60 years), central nervous system dysfunction at admission, nonuse of antithyroid drugs and β-blockade, and requirement for mechanical ventilation and therapeutic plasma exchange combined with hemodialysis. The present study identified clinical features associated with mortality of thyroid storm using large-scale data. Physicians should pay special attention to older patients with thyrotoxicosis and coexisting central nervous system dysfunction. Future prospective studies are needed to clarify treatment options that could improve the survival outcomes of thyroid storm. PMID:26886648

  3. 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.

  4. Power grid disturbances and polar cap index during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Stauning, Peter

    2013-06-01

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

  5. 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.

  6. 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…

  7. 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…

  8. 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,…

  9. 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

  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