Advances in Hurricane Research

This book provides a wealth of new information, ideas and analysis on some of the key unknowns in hurricane research. Topics covered include the numerical prediction systems for tropical cyclone development, the use of remote sensing methods for tropical cyclone development, a parametric surface wind model for tropical cyclones, a micrometeorological analysis of the wind as a hurricane passes over Houston, USA, the meteorological passage of numerous tropical cyclones as they pass over the South China Sea, simulation modelling of evacuations by motorised vehicles in Alabama, the influence of high stream-flow events on nutrient flows in the post hurricane period, a reviews of the medical needs, both physical and psychological of children in a post hurricane scenario and finally the impact of two hurricanes on Ireland. Hurricanes discussed in the various chapters include Katrina, Ike, Isidore, Humberto, Debbie and Charley and many others in the North Atlantic as well as numerous tropical cyclones in the South China Sea

Characteristics of tropical cyclones in the North Atlantic and East Pacific.

In this dissertation, I present a series of investigations to expand our understanding of TCs in the East Pacific and North Atlantic basins. First, I developed and applied a climatological tool that quickly and succinctly displays the spread of historical TC tracks for any point in the North Atlantic basin. This tool is useful in all parts of a basin because it is derived from prior storm motion trajectories and summarily captures the historical synoptic and mesoscale steering patterns. It displays the strength of the climatological signal and allow for rapid qualitative comparison between historical TC tracks and NWP models. Second, I have used a robust statistical technique to quantify the relationships between fifteen different metrics of TC activity in nine ocean basins and twelve climate indices of the leading modes of atmospheric and oceanic variability. In a thorough, encyclopedic manner, over 12,000 Spearman rank correlation coefficients were calculated and examined to identify relationships between TCs and their environment. This investigation was not limited to the East Pacific or North Atlantic, and new climatic associations were found between seasonal levels of TC activity and the major climate indices across the nine basins. This information is critical to forecasters, economists, actuaries, energy traders, and societal planners who apply knowledge of levels of TC activity on intraseasonal to interdecadal timescales. The statistics are also valuable to climatologists seeking to understand how regional TC frequency will change as the global climate warms. Third, I have examined the leading intraseasonal mode of atmospheric and oceanic variability, the Madden-Julian Oscillation (MJO), and discovered statistically significant relationships with the frequency of TC genesis, intensification, and landfall over the nine basins. Like the significance of the longer-period oscillations to the frequency of TC activity on intraseasonal and longer timescales, these results are highly relevant to the problem of short-term (one- to two-week) predictability of TC activity. These three investigations demonstrate the utility of historical datasets across a wide range of applications, from short-term forecasting to climate studies. In this way, the results highlighted in this dissertation represent a significant and positive contribution to meteorology. Collectively, they reveal multiple characteristics of TCs in the East Pacific and North Atlantic and provide greater understanding of the complex interactions between TCs and their surrounding larger-scale environment

High resolution simulations of the microphysics and electrification in hurricane-like vortices over warm ocean and at landfall.

Cloud-to-ground (CG) lightning bursts in the eyewall of mature tropical cyclones (TCs) are believed to be good indicators of imminent intensification of these systems. While numerous well-documented observational cases exist in the literature, no modeling studies of the electrification processes within TCs have been made so far. At present, little is known about the evolution of charges and subsequent electrification in mature TCs. Towards this goal, a numerical cloud model featuring a 12-class bulk microphysics scheme and a three-dimensional branched lightning module is utilized to simulate the evolution of the microphysics fields and subsequent electrical activity in an idealized hurricane like vortex over ocean (OCEAN case). In a separate experiment (LAND case), two simulations were carried out a slightly coarser resolution. The first simulation was similar than the OCEAN case, while in the second simulation, a simplistic landmass was introduced in the domain in order to investigate the effect of reduced sensible and moisture flux and enhanced drag on the TC's dynamics, microphysics and electrification.Preliminary results of the OCEAN TC case showed that the highest total lightning flash rate were primarily found within the eyewall but seldom within the stronger cells forming the outer rainbands where updraft speeds rarely exceeded 10 m s-1 and 15 m s-1, respectively, consistent with observations. As expected, these regions of the storm were generally characterized by moderate total graupel mixing ratio (> 0.5 g kg -1) and moderate cloud water content (> 0.2 g kg-1). Using the Saunders and Peck non-inductive (NI) charging scheme and moderate inductive charging settings, the inner eyewall region exhibited a normal tripole charge structure (a mid-level negative charge layer amidst two positive charges regions) while a normal dipole (a positive charge region atop a negative charge region at mid-levels) was observed in the outer eyewall stratiform region and in the strongest cells forming the outer rainbands. The charges forming the normal dipole in the outer eyewall were generated within the eyewall via NI charging in the mixed-phase region at mid-levels (near the -15° C isotherm).In summary, despite producing quantitatively different results, the qualitative aspects of the simulated squall line dynamics, microphysics and lightning were overall similar. This suggested that the hurricane simulations presented in this study could still provide a good and useful qualitative insight of the storm's dynamical, microphysical and electrical properties.The simulated tropical squall line exhibited many features consistent with observations. In particular, the updraft speeds were generally much weaker than their continental counterparts, which was in turn consistent with relatively shallow 30 dBZ echo tops and lower content of graupel and supercooled water droplets within the mixed phase layer. This general reduction of graupel and supercooled water was partly caused by a rapid depletion of liquid water by enhanced warm rain processes ahead of the line, in agreement with previous studies. The stratiform region was almost exclusively composed of light ice crystals and snow aggregates, with discrete regions, however, containing small amounts of graupel (∼ 0.1-0.3 g kg-1) All of these factors combined resulted in a system producing overall little lightning.In the LAND TC experiment the landfalling storm was, as expected, much weaker (higher surface pressure, weaker winds) and less organized than the storm evolving over ocean. The weaker landfalling storm was associated with smaller eyewall total updraft mass flux and shallower echo tops (particularly 30 dBZ and greater) in turn consistent with smaller total graupel volume aloft and an overall smaller total lightning activity. Perhaps the most interesting finding of the LAND experiment was that several +CG flashes were produced after landfall, which was not observed in the control simulation over ocean. This indicated that, as suggested by observations, there exists a qualitative difference in the storm electrical behavior after landfall, which as we showed, was directly linked to its change in kinematical and microphysical fields. Observational studies, however, showed that this difference in lightning behavior over land versus over ocean varied from case to case, and therefore could not be generalized. (Abstract shortened by UMI.)Before carrying out these experiments, however, it was necessary to test the reliability of the model in maritime tropical environment. For this purpose, an additional idealized high-resolution simulation of a well-documented TOGA COARE squall line case was carried out. Moreover, for a single microphysical and electrical evolution, the latter experiment was carried out at three additional horizontal grid spacings to determine how the storm's dynamical, microphysical and electrical properties responded to these changes

A hydroclimatic assessment of the U.S. corn belt across spatial and temporal scales

The term hydroclimate is used to describe the climate of a given location as determined by the incident radiant energy (temperature) and the existence of water in its various forms on Earth. Two types of climate comprise the science of hydroclimatology: the climate as established by general global circulation patterns at specific locations on Earth (large-scale climate) and the climate established at Earth\u27s surface resulting from the daily fluxes of radiant energy and water in its various forms between the atmosphere, Earth\u27s surface, and the subsurface (local-scale climate) (Shelton 2009). This dissertation investigates different spatial and temporal scales of the U.S. Corn Belt hydroclimate and includes analysis of large- and local-scale hydroclimatic feedbacks. Large-scale hydroclimate research in this assessment investigates how general circulation patterns and teleconnections, specifically the El Ni?o-Southern Oscillation and the Arctic Oscillation, influence climate variability in the form of temperature and precipitation patterns across the U.S. Corn Belt with findings applicable to agricultural decision making. A large- and local-scale hydroclimatic assessment examines the rainfall contribution of land-falling tropical cyclones to the Eastern U.S. Corn Belt. Locale-scale hydroclimate research considers the role of land-surface feedbacks in the life cycle of land-falling tropical cyclones. Results from the assessments that comprise this dissertation show that the spatial and temporal scales at which hydroclimatic feedbacks are examined are important to the understanding of hydroclimate system interactions. It is suggested from the results of this comprehensive assessment that the newly identified, large- and local-scale hydroclimatic feedbacks be given stronger consideration in forecasts and climate projection models. Additionally, it is suggested that more hydroclimate assessments across spatial and temporal scales be completed to better prepare for and mitigate the effects of projected climate variability and climate change. A framework for climatological applications to agronomy is discussed in the first chapter, with the findings of the hydroclimatological assessments in subsequent chapters primarily applied to agronomic decision making

Laboratory for Atmospheres 2008 Technical Highlights

The 2008 Technical Highlights describes the efforts of all members of the Laboratory for Atmospheres. Their dedication to advancing Earth Science through conducting research, developing and running models, designing instruments, managing projects, running field campaigns, and numerous other activities, is highlighted in this report. The Laboratory for Atmospheres (Code 613) is part of the Earth Sciences Division (Code 610), formerly the Earth Sun Exploration Division, under the Sciences and Exploration Directorate (Code 600) based at NASA s Goddard Space Flight Center in Greenbelt, Maryland. In line with NASA s Exploration Initiative, the Laboratory executes a comprehensive research and technology development program dedicated to advancing knowledge and understanding of the atmospheres of Earth and other planets. The research program is aimed at understanding the influence of solar variability on the Earth s climate; predicting the weather and climate of Earth; understanding the structure, dynamics, and radiative properties of precipitation, clouds, and aerosols; understanding atmospheric chemistry, especially the role of natural and anthropogenic trace species on the ozone balance in the stratosphere and the troposphere; and advancing our understanding of physical properties of Earth s atmosphere. The research program identifies problems and requirements for atmospheric observations via satellite missions. Laboratory scientists conceive, design, develop, and implement ultraviolet, infrared, optical, radar, laser, and lidar technology for remote sensing of the atmosphere. Laboratory members conduct field measurements for satellite data calibration and validation, and carry out numerous modeling activities. These modeling activities include climate model simulations, modeling the chemistry and transport of trace species on regional-to-global scales, cloud-resolving models, and development of next-generation Earth system models. Interdisciplinary research is carried out in collaboration with other laboratories and research groups within the Earth Sciences Division, across the Sciences and Exploration Directorate, and with partners in universities and other Government agencies. The Laboratory for Atmospheres is a vital participant in NASA s research agenda. Our Laboratory often has relatively large programs, sizable satellite missions, and observational campaigns that require the cooperative and collaborative efforts of many scientists. We ensure an appropriate balance between our scientists responsibility for these large collaborative projects and their need for an active individual research agenda. This balance allows members of the Laboratory to continuously improve their scientific credentials. Members of the Laboratory interact with the general public to support a wide range of interests in the atmospheric sciences. Among other activities, the Laboratory raises the public s awareness of atmospheric science by presenting public lectures and demonstrations, by making scientific data available to wide audiences, by teaching, and by mentoring students and teachers. The Laboratory makes substantial efforts to attract new scientists to the various areas of atmospheric research. We strongly encourage the establishment of partnerships with Federal and state agencies that have operational responsibilities to promote the societal application of our science products. This report describes our role in NASA s mission, gives a broad description of our research, and summarizes our scientists major accomplishments during calendar year 2008. The report also contains useful information on human resources, scientific interactions, and outreach activities

State of the climate in 2013

In 2013, the vast majority of the monitored climate variables reported here maintained trends established in recent decades. ENSO was in a neutral state during the entire year, remaining mostly on the cool side of neutral with modest impacts on regional weather patterns around the world. This follows several years dominated by the effects of either La Niña or El Niño events. According to several independent analyses, 2013 was again among the 10 warmest years on record at the global scale, both at the Earths surface and through the troposphere. Some regions in the Southern Hemisphere had record or near-record high temperatures for the year. Australia observed its hottest year on record, while Argentina and New Zealand reported their second and third hottest years, respectively. In Antarctica, Amundsen-Scott South Pole Station reported its highest annual temperature since records began in 1957. At the opposite pole, the Arctic observed its seventh warmest year since records began in the early 20th century. At 20-m depth, record high temperatures were measured at some permafrost stations on the North Slope of Alaska and in the Brooks Range. In the Northern Hemisphere extratropics, anomalous meridional atmospheric circulation occurred throughout much of the year, leading to marked regional extremes of both temperature and precipitation. Cold temperature anomalies during winter across Eurasia were followed by warm spring temperature anomalies, which were linked to a new record low Eurasian snow cover extent in May. Minimum sea ice extent in the Arctic was the sixth lowest since satellite observations began in 1979. Including 2013, all seven lowest extents on record have occurred in the past seven years. Antarctica, on the other hand, had above-average sea ice extent throughout 2013, with 116 days of new daily high extent records, including a new daily maximum sea ice area of 19.57 million km2 reached on 1 October. ENSO-neutral conditions in the eastern central Pacific Ocean and a negative Pacific decadal oscillation pattern in the North Pacific had the largest impacts on the global sea surface temperature in 2013. The North Pacific reached a historic high temperature in 2013 and on balance the globally-averaged sea surface temperature was among the 10 highest on record. Overall, the salt content in nearsurface ocean waters increased while in intermediate waters it decreased. Global mean sea level continued to rise during 2013, on pace with a trend of 3.2 mm yr-1 over the past two decades. A portion of this trend (0.5 mm yr-1) has been attributed to natural variability associated with the Pacific decadal oscillation as well as to ongoing contributions from the melting of glaciers and ice sheets and ocean warming. Global tropical cyclone frequency during 2013 was slightly above average with a total of 94 storms, although the North Atlantic Basin had its quietest hurricane season since 1994. In the Western North Pacific Basin, Super Typhoon Haiyan, the deadliest tropical cyclone of 2013, had 1-minute sustained winds estimated to be 170 kt (87.5 m s-1) on 7 November, the highest wind speed ever assigned to a tropical cyclone. High storm surge was also associated with Haiyan as it made landfall over the central Philippines, an area where sea level is currently at historic highs, increasing by 200 mm since 1970. In the atmosphere, carbon dioxide, methane, and nitrous oxide all continued to increase in 2013. As in previous years, each of these major greenhouse gases once again reached historic high concentrations. In the Arctic, carbon dioxide and methane increased at the same rate as the global increase. These increases are likely due to export from lower latitudes rather than a consequence of increases in Arctic sources, such as thawing permafrost. At Mauna Loa, Hawaii, for the first time since measurements began in 1958, the daily average mixing ratio of carbon dioxide exceeded 400 ppm on 9 May. The state of these variables, along with dozens of others, and the 2013 climate conditions of regions around the world are discussed in further detail in this 24th edition of the State of the Climate series. © 2014, American Meteorological Society. All rights reserved

Extratropical Cyclones and Associated Climate Impacts in the Northeastern United States

There is growing concern that some aspects of severe weather could become more frequent and extreme across the northeastern United States (USNE) as a consequence of climate change. Extratropical cyclones and frontal systems are a common factor in a variety of severe weather hazards in the region. This dissertation examines three types of meteorological events impacting the USNE – ice storms, heavy rainfall, and high-wind events. The first research topic utilizes the Weather Research and Forecasting (WRF) model in a case study of the December 2013 New England ice storm. In this analysis, a series of tests are conducted to examine how choice of planetary boundary layer physics and other factors affect the model skill in comparison to observations. The results show that near-surface variables are highly sensitive to model setup, highlighting the need for careful testing prior to use. The second research topic explores large-scale teleconnections associated with the documented increase in summer precipitation across the USNE over the past two decades. It is shown that the precipitation surplus occurs in likely teleconnection with increased frequency of high pressure blocking over Greenland. As the current generation of climate models do not correctly depict seasonal patterns or trends in precipitation for the USNE, identifying the association between Greenland blocking and recent precipitation changes across the USNE is crucial for understanding the shortcomings for climate projections for the region. The third research topic is an analysis of the frequency and intensity of mid-autumn wind storms in New England. Fall season storms can have dominant cold-season characteristics, while also being fueled by warm-season moisture sources or the result of an extratropical transition. While the results show an increase in storm total precipitation, there are no significant trends in overall wind storm frequency or intensity with respect to central pressure or surface wind speeds. Nevertheless, storm severity is only one factor that contributes to damage from high wind events. As a whole, this dissertation provides insights to how precipitation and storms are changing across the USNE, while highlighting some of the challenges of weather and climate prediction at regional scales