Download Free Convective Structure And Its Evolution In Tropical Cyclones As Observed By Passive Microwave Sensors In Relation To Intensity Change Book in PDF and EPUB Free Download. You can read online Convective Structure And Its Evolution In Tropical Cyclones As Observed By Passive Microwave Sensors In Relation To Intensity Change and write the review.

The use of passive microwave sensors in analysis of tropical cyclones provide unique insight into the microphysical attributes and system structure opposed to other instruments that are only able to detect information about the cloud top. With the ability to infer information about key microphysical processes and structure at high resolution, these platforms provide a glimpse into tropical cyclone development and intensification over systems0́9 life cycles. In particular, passive microwave observations have the potential to depict crucial precursors of rapid intensification (RI; defined as a wind increase of 30 kt/24 hr). A dataset with a common resolution of 8 km across all channels is developed for the Special Sensor Microwave Imager (SSM/I) from 1987-2008 and Tropical Rainfall Measuring Mission Microwave Imager (TMI) for 1997-2008. Statistical metrics are calculated for each storm overpass using 85 GHz and 37 GHz polarization corrected temperatures as well as microwave rain rate estimates. These products are examined as a function of azimuth and annuli in true-north, storm-relative motion, and shear-relative coordinates and evaluated in terms of intensity (wind speed) and intensity change (wind speed change over time). To examine predictive potential of these sensors, the brightness temperature statistics are evaluated in terms of linear correlations between intensity and its change. Highest values occur on the order of 0.7, and are seen at radii of 110 km between median values for 85 GHz PCT and rain rates with observed intensity. An increase in skill is evident following the initial satellite overpass, suggesting a lag between latent heating at the time of overpass and the resultant intensification. Despite this, correlation is consistently less skillful for evaluations of intensity change with values at short time changes of around 0.3. The distribution of statistical values are also evaluated in the context of the dataset with median values at the 110 km distance showing the greatest distinction of 85 GHz PCTs and rain rates for storms at the onset of RI and those that are not, with less variation seen for percentiles > 90% that are indicative of isolated convective activity. With the differentiation in structure noted between RI and non-RI storms, composites are created for each of the brightness temperature products, with a distinct modest convective ring structure evident at the onset of RI that is not present in the non-RI class. Over time this convective ring shows a tendency to contract and intensify over the 24 hour period examined for RI, with the increased latent heating over a more focused area acting to increase the system intensity. Through these evaluations the continued importance spatial convective coverage and axisymmetricization is underscored in intensity and intensity change evaluation, with a lack of signal seen in more isolated convective predictors.
A better understanding of the role mesoscale convective systems (MCS) play in the genesis stages of tropical cyclones will increase the ability to predict their formation. This thesis employs polar-orbiter microwave and geostationary infrared satellite imagery to document MCS structure and evolution during tropical cyclone genesis. Microwave imagery at frequencies of 19.35 GHz and 85.5 GHz are used to define convective and stratiform cloud areal amounts, percent coverage, and time-integrated rain rates. Collocations with geostationary infrared images are used to calibrate that imagery so that the hourly values may be calculated until another microwave image is available. Specifically, seven MCSs in two disturbances that eventually developed into tropical cyclones were analyzed. Two MCSs in non-developing storms are also described for contrast.
Tropical Cyclones and hurricanes, long feared for the death and destruction that often accompanies them, are among the most fascinating of atmospheric phenomena. Created by thermodynamic processes, they unleash vast amounts of energy and influence a wide variety of natural processes along their paths. Richard Anthes tells the story of tropical cyclones creation and destruction, of meteorology's successes in understanding, modeling and predicting their behavior, and of the attempts to modify them. The book begins with a lively introduction to hurricanes, their awesome power, and their effects on individuals and societies in the past and present. The characteristics of the mature hurricane are revealed by consideration of rawinsonde, aircraft and satellite data. The physical processes responsible for the development and maintenance of tropical cyclones are treated comprehensively, and illustrated with both qualitative and quantitative examples. The role of the planetary boundary layer, cumulus convection and radiation are all discussed in detail. Progress in numerical simulation of tropical cyclones is carefully reviewed. Modern, three-dimensional models succeed in simulating observed features such as the eye and spiral rain bands and in predicting storm motion over time intervals of three days. Current capabilities to predict and modify hurricanes and tropical cyclones are fully examined. The methods and difficulties of operational forecasting, the economic aspects of storm predictions, and the trends in accuracy of offical forecasts are all considered. The potential benefits and scientific problems associated with hurricane modification are discussed as part of a review of experimental and theoretical results on the consquences of seeding hurricane clouds. A unique feature of the book is a thorough treatment of the interactions between storm and ocean, with both observations and thery being integrated to provide a complete description.
Clouds and Their Climatic Impacts Clouds are an influential and complex element of Earth’s climate system. They evolve rapidly in time and exist over small spatial scales, but also affect global radiative balance and large-scale circulations. With more powerful models and extensive observations now at our disposal, the climate impact of clouds is receiving ever more research attention. Clouds and Their Climatic Impacts: Radiation, Circulation, and Precipitation presents an overview of our current understanding on various types of clouds and cloud systems and their multifaceted role in the radiative budget, circulation patterns, and rainfall. Volume highlights include: Interactions of aerosol with both liquid and ice clouds Surface and atmospheric cloud radiative feedbacks and effects Arctic, extratropical, and tropical clouds Cloud-circulation coupling at global, meso, and micro scales Precipitation efficiency, phase, and measurements The role of machine learning in understanding clouds and climate The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
"In the western North Pacific Ocean, tropical cyclone (TC) hazards, including strong winds, storm surge, high waves, and heavy rainfall, threaten archipelagos, densely crowded coastlines, and naval forces ashore and afloat. To accurately forecast TC track and intensity, meteorologists at the Joint Typhoon Warning Center (JTWC) must start from a thorough understanding of the TC's current structure. To accomplish this mission, they rely heavily upon satellite observations, particularly measurements in the water vapor (WV) and infrared (IR) channels on geostationary satellites. Therefore, it is critical to develop products that identify key TC structures in geostationary satellite data and track them over time, as these data are often the only real-time information available to the forecasters. This project examined satellite brightness temperatures in the WV and IR channels in 5 typhoon-strength TCs during the 2012 season to first identify the eye, eyewall, and regions of deep convection, and then to investigate the evolution of those features over time. The eye was defined in this study from the storm center out to the location of the minimum second derivative of IR brightness temperatures. The eyewall, which contains the strongest winds and deepest convective clouds, was divided into lower, middle, and upper sections using IR and WV brightness temperatures. Eyewall slope was calculated between the break points of the eyewall using brightness temperatures and radial distance. The IR brightness temperatures in the upper eyewall were found to be moderately negatively correlated to TC intensity. Eyewall slope, particularly in the region of the steep IR Tb gradient that included the lower eyewall, was also found to be moderately negatively correlated to TC intensity." -- Abstract.
The thesis work was in two major parts: development and testing of a new approach to detecting and tracking tropical cyclones in climate models; and application of an extreme value statistical approach to enable assessment of changes in weather extremes from climate models. The tracking algorithm applied a creative phase-space approach to differentiate between modeled tropical cyclones and their mid-latitude cousins. A feature here was the careful attention to sensitivity to choice of selection parameters, which is considerable. The major finding was that the changes over time were relatively insensitive to these details. This new approach will improve and add confidence to future assessments of climate impacts on hurricanes. The extremes approach utilized the Generalized Pareto Distribution (one of the standard approaches to statistics of extremes) applied to present and future hurricane distributions as modeled by a regional climate model, then applied the changes to current observations to extract the changes in the extremes. Since climate models cannot resolve these extremes directly, this provides an excellent method of determining weather extremes in general. This is of considerable societal importance as we are most vulnerable to such extremes and knowledge of their changes enables improved planning and adaptation strategies.