Abstracts
| Lightning and Electric Field Measurements during the Tropical Cloud Systems and Processes (TCSP) Experiment
Richard Blakeslee, PI, NASA Marshall Space Flight Center, Global Hydrology and Climate Center, 320 Sparkman Dr. Huntsville, AL. 35805, rich.blakeslee@msfc.nasa.gov The Lightning Instrument Package (LIP) is being flown on a high altitude ER-2 to study the precipitation and convective processes during the Tropical Cloud Systems and Processes (TCSP) experiment. Lightning and electric field observations, in conjunction with other measurements, will provide improved assessments of the development and evolution of convective intensity, cloud microphysics, precipitation development, and ice flux (including anvil development and evolution). Comprehensive data sets using a ground-based, aircraft, balloon-borne, and satellite platforms will be collected by NASA and collaborating agencies (especial NOAA) during TCSP. These measurements will yield high spatial and temporal information to improve the understanding and prediction of the genesis, intensity, motion, rainfall potential, and landfall impacts of tropical cloud systems. |
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Early Stages of Tropical Cyclone Genesis in the Pacific Ocean Mark Bourassa, Center for Ocean-Atmospheric Prediction Studies, Florida State University, Tallahassee, FL 32306-2840 or Department of Meteorology, Florida State University, Tallahassee, FL 32306-4520, bourassa@coaps.fsu.edu Paul Reasor, Department of Meteorology, Florida State University, Tallahassee, FL 32306-4520, reasor@met.fsu.edu Phil Cunningham, Department of Meteorology, Florida State University, Tallahassee, FL 32306-4520, cunningham@met.fsu.edu Our objective is to examine the structure and evolution of the mesoscale and synoptic-scale environment during the early stages of eastern and western Pacific tropical cyclone genesis, making use of a wide variety of both conventional and non-conventional data sources. Specifically, the objectives of this research are: 0. Refine and complete testing of an objective method for locating tropical disturbances. The proposed research activities have been designed to take advantage of the unique observational and diagnostic infrastructure developed by the PIs over recent years, as well as the data and insights from research commitments. The expected significance of this proposed research is as follows: 1. Demonstrate the value of satellite remotely sensed data in detailed studies of tropical cyclone genesis, particularly in regions where conventional data are unavailable. |
| Hurricane Formation and Evolution Determined from Observations and High-Resolution Simulations Tropical Cloud Systems and Processes (TCSP) Dr. Scott A. Braun, PI, Laboratory for Atmospheres (Code 912), NASA/Goddard Space Flight Center, Greenbelt, MD 20771, Tel: (301) 614-6316, Fax: (301) 614-5492, Scott.A.Braun@.nasa.gov Professor Michael T. Montgomery, Co-I, Department of Atmospheric Sciences, Colorado State University, Fort Collins, CO 80523, Tel: (970) 491-8355, Fax: (970) 491-8449, mtm@atmos.colostate.edu Dr. Edward Zipser, Collaborator, ezipser@met.utah.edu This proposal describes high-resolution (~250m-4 km) numerical modeling of hurricanes from CAMEX-3, CAMEX-4, and expected simulations for TCSP. Emphasis will be on the use of various aircraft and satellite data for model validation as well as examination of simulations and observations for improved understanding of physical and dynamical processes within tropical cyclones. The primary model used is the Weather Research and Forecast (WRF) model. The proposal addresses several key areas of research relevant to NASA and TCSP: • Analysis of field observations and satellite data to describe the evolution and structure of selected cases of tropical cyclone genesis. |
| Precipitation Response to Environmental Forcing in Tropical Cyclones
Dan Cecil, PI, Department of Atmospheric Science, University of Alabama in Huntsville, daniel.cecil@msfc.nasa.gov Great advances have been made in recent years toward understanding and predicting tropical cyclone motion. Limited progress has also been made with tropical cyclone intensity change. Tropical cyclone rainfall has received less attention from the research community, although freshwater flooding is the leading cause of deaths in recent tropical cyclones. The goal of this investigation is to examine and quantify relationships between environmental forcing and the magnitude and distribution of precipitation associated with tropical cloud systems, especially tropical cyclones. This research consists of two primary components:(1) examination of satellite-derived precipitation, as it relates to environmental conditions for a large sample of tropical cyclones;(2) examination of precipitation observed by both satellite and research aircraft in field program cases, as this precipitation relates to environmental conditions observed by research aircraft. The first component uses satellite observations and global analyses to identify and quantify trends relating tropical cyclone precipitation to environmental forcing. The second component exploits specialized NASA observations at high spatial resolutions to understand those processes which shape the precipitation field. The airborne observations for select cases supplement the satellite observations for the larger set of storms. The CAMEX-3 and -4 datasets include multiple hurricane cases. Assuming the TCSP field campaign yields tropical depression and tropical storm cases, a diverse set of storms will be available for study. This study will also benefit from mesoscale convective system (MCS) cases in CAMEX and TCSP field campaigns. Similar processes are likely at work in some MCS and tropical cyclone cases, particularly for MCS with pronounced mid-level circulations and for weak tropical cyclones. The anticipated results will advance general understanding of tropical precipitation, provide validation for theoretical and modeling studies, and enable improved forecasts through subjective interpretation, statistical models, and/or more realistic portrayal of tropical cyclones in dynamic models. |
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Understanding the mechanisms and effects of ice nucleation in tropical cyclones Paul Ginoux (PI), NOAA Geophysical Fluid Dynamics Laboratory (GFDL), Atmospheric Physics and Chemistry Division, Forrestal Campus, Route 1, PO Box 308, Princeton, NJ 08542, Email: Paul.Ginoux@noaa.gov Vaughan Phillips (Co-I), Princeton University & NOAA-GFDL, Forrestal Campus, Route 1, PO Box 308, Princeton, NJ 08542, Email: Vaughan.Phillips@noaa.gov Our proposal will investigate the interactions between tropospheric aerosols and clouds. This will utilize and extend the existing capabilities of an Explicit Microphysics Model (EMM) and a 3D Cloud-Resolving Model (CRM) with double moment microphysics at GFDL. Our goals are:- (1) to analyze the correlations between satellite- and aircraft-data related to aerosols and cloud-cover properties, using TCSP observations; (2) to improve the EMM, which already has the unique capability of predicting particle properties (shape, bulk density, size) without categorization assumptions and to predict the particle size distributions; (3) to improve the bulk microphysics scheme of the CRM, enabling it to predict the mass, concentration and possibly certain properties of particles, with dependences of their nucleation and coagulation processes on the ambient turbulence and in-cloud electric fields; and (4) to answer scientific questions related to the role of cloud dynamics, electric fields, turbulence and other ambient conditions in the nucleation processes that provide the linkage between aerosol and ice particle properties in cirrus. Particular focus will be given to the competition between the homogeneous freezing of aerosol and that of cloud-droplets. |
| A Data and Information Management System for the TCSP Field Program
Michael Goodman, PI, Mail Suite 5C33, Science Mission Directorate, NASA Headquarters, 300 E St. SW, Washington DC 20546, michael.goodman@nasa.gov The NASA Marshall Space Flight Center’s Global Hydrology Resource Center will implement and operate an information system for project coordination, decision support, and the collection, archive and dissemination of data and information to support field experiment operations together with pre-experiment coordination and post-experiment data analysis. This information system will be web-driven and updated in near-real time. In the planning phase of the TCSP missions, the information management web site will serve as a communication forum and information clearinghouse for the TCSP investigators. The system will provide field scientists, program and project managers, atmospheric researchers, and modelers with timely access to surface and aircraft instrument data, key satellite observations, customized subsetted data sets, forecasts, and aircraft and instrument operations status during the execution of the field phase and the post-experiment analysis. A key element of the proposal will be enabling efficient and easy exchange of diverse data sets among the TCSP scientists and the research community at large. The TCSP data sets managed by the data system will be fully described with the Earth Science Markup Language metadata package and may be easily custom subsetted. By applying Open GIS Consortium standards of web mapping, coverage and feature services (WMS, WCS, WFS) to the TCSP field and satellite data sets, they will be widely accessible and useable to the science community. |
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Studies of Tropical Cyclone Genesis Using ER-2 Radars Gerald Heymsfield, PI, Goddard Space Flight Center, Gerald.heymsfield@nasa.gov Lihua Li, Co-I, UMBC/GEST, lihua@agnes.gsfc.nasa.gov Lin Tian, Co-I, UMBC/GEST, tian@agnes.gsfc.nasa.gov Michael Black, Co-I, NOAA/HRD, Michael.Black@noaa.gov Prior work using the 9.6 GHz ER-2 Doppler Radar (EDOP) CAMEX studies focused on the structure of convective bursts, warm cores, and the role of shear on tropical storm structure and intensification. The focus of this work is on tropical cyclone genesis emphasizing early stages of development. We are interested in the understanding the processes that govern development of a vortex develops in a convective cluster or mesoscale system. This effort will utilize the ER-2 measurements along with satellite and other aircraft measurements to improve our understanding of why some MCSs develop into tropical cyclones. This effort will support the field deployment of the ER-2 radars (ER-2 Doppler Radar System EDOP and the 94 GHz Cloud Radar System (CRS)) that will provide key information on the vertical structure of convection and MCSs. The work will apply data synthesis and analysis methodologies developed during previous field campaigns to the new data sets collected during TCSP. Specific topics to be investigated are: 1) role of convective bursts in tropical storm genesis, 2) statistical properties of vertical motions and reflectivity in MCS stratiform and convective regions, 3) general flow characteristics of developing storms, 4) radar microphysical retrievals from ER-2 radars, and 5) jointly with NOAA HRD, examination of the vertical air motion and fallspeeds in various precipitation regions using stacked flights of ER-2 nadir viewing, and P3 zenith viewing Doppler measurements. Science collaboration with NOAA HRD (through one of the Co.I’s and other proposals) will address the radar-derived vertical velocity assumptions as well as engage in joint case studies on easterly wave development and tropical storm genesis. |
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A Study of Tropical Cyclone Rainfall, Genesis, and Intensity Change Using Blended Spaceborne, Airborne, and Earth-based Observations Robbie Hood, PI, Earth Science Department, NASA Marshall Space Flight Center, rhood@hq.nasa.gov Daniel Cecil, Co-I, Atmospheric Science Department, University of Alabama in Huntsville, daniel.cecil@msfc.nasa.gov Frank LaFontaine, Co-I, Raytheon ITSS, Huntsville, Alabama, Frank.LaFontaine@msfc.nasa.gov Mike Botts, Co-I, Atmospheric Science Department, University of Alabama in Huntsville, mike.botts@nsstc.uah.edu Anthony Guillory, Earth Science Department, NASA Marshall Space Flight Center Our goals for TCSP will be to conduct passive microwave sampling of tropical rainfall during the field phase, to study the coupled relationship of convective intensity with low-level wind circulation during tropical cyclone genesis and intensity change, to investigate the best blend of satellite, sub-orbital, and ground-based observations to monitor tropical rainfall and cyclone development, and to collaborate with other TCSP Science Team members to evaluate how sub-orbital observations might routinely be used from a remotely piloted aircraft to contribute to improved hurricane forecasting. More specifically, a precipitation classification scheme based on airborne passive microwave information and evaluated with airborne Doppler radar data has been developed and matched with corresponding electric field information. This technique shows promise as a real-time analysis tool for monitoring precipitation, vertical motion of hydrometeors, and convective intensity from traditional aircraft or uninhabited aerial vehicles (UAVs). Building upon the synergy of these types of data we will explore how to blend other airborne, spaceborne, and Earth-based observations to monitor tropical cyclone rainfall, genesis, and intensity change. We are particularly interested in evaluating how spaceborne observations might be routinely enhanced or augmented with high-resolution airborne information from a remotely piloted vehicle to improve numerical model initializations and satellite instrument and product validation. We will propose to fly the Advanced Microwave Precipitation Radiometer (AMPR) on a high altitude aircraft but will also seek to collaborate with other instrument teams to identify optimal payload components for future UAV or ultra-long duration airship missions. To facilitate this effort, we will also design a testbed demonstration of information technology techniques developed for sensor web applications. This demonstration will evaluate how a future Earth observing network might successfully blend data from a variety of sources for more comprehensive monitoring capabilities of tropical cyclones and other critical weather events. |
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Assimilation, Ensemble Forecasts and Adaptive Strategies for Hurricane Genesis using TCSP Datasets Dr. T.N. Krishnamurti, PI, Florida State University, tnk@io.met.fsu.edu Our research will focus on several TCSP objectives. We have participated in the field phase and the post-field phase research for both CAMEX-3 and CAMEX-4. Review of our past work in the area of data validation (NASA DC8, ER2 and other participating aircraft), data assimilation (3D-VAR), high-resolution modeling of hurricane forecast sensitivity to dynamical/physical processes and specialized data sets (aircraft based dropwindsonde and moisture profiles from LASE) is presented here. In addition to those activities we have provided a real-time hurricane forecast capability that brings in a statistical post-processing of multimodel ensemble forecasts – called the FSU superensemble. This was introduced as a support product during the field phase activities of CAMEX-3 and CAMEX-4. Based on these past data sets, our research has focused on forecasts of track and intensity; and output diagnostic studies that have deployed non-hydrostatic microphysical models using tools such as the angular momentum principles and scale interactions among explicitly resolved clouds and hurricane scales. The research will focus on the “genesis of hurricane” issue. We are preparing our modeling suite to address this problem in a comprehensive manner. This will include the following: a) Data validation issues related to the forthcoming TCSP campaign, b) Advanced data assimilation procedure where higher resolution data sets and assimilation model will be deployed, c) Forecast sensitivity studies will be addressed for data types, model physics, model dynamics and model microphysics, d) Data sensitivity related modeling issues extend to the design and execution of adaptive observational strategies that have been vigorously tested over several CAMEX-3 and CAMEX-4 hurricanes, with very promising possibilities for a limited real-time support for the forthcoming TCSP campaign, and e) Diagnostic post processing of model results will be one of the major areas of emphasis. Given a realistic simulation of the genesis from a non-hydrostatic microphysical model, we plan to address the issue of genesis with an emphasis on the understanding of the organization of convection using a storm-relative polar coordinate as a frame of reference. Here spectral transforms of the microphysical equations will be cast in polar coordinates to examine the interactions among dynamical, physical, microphysical and resolved cloud scales. This will be examined in detail, since the evolution of convective organization and the ensuing scale interactions are central to the genesis issue. The P.I. along with one research associate and two graduate students will participate in the field phase at Costa Rica. They will assist with real-time guidance based on the FSU multimodel superensemble forecasts and on the possible deployment of targeted observations for real-time modeling at FSU. The FSU modeling suite includes the FSU global spectral model at a resolution T255, the FSU regional spectral model at 0.25ºlat/lon resolution and the NCAR/PennState MM5 model (that is non-hydrostatic and microphysical) at its highest resolution of 1 km. The FSU models include a detailed physical initialization for precipitation, precipitable water and moisture profiles. |
| Hurricane Research with the High Altitude MMIC Sounding Radiometer Bjorn Lambrigtsen, PI, Jet Propulsion Laboratory, lambrigtsen@jpl.nasa.gov We will use the High Altitude MMIC Sounding Radiometer (HAMSR) to provide temperature and water vapor soundings of the atmosphere from the flight altitude to the surface. HAMSR, which is currently configured to fly on the ER-2 - in one of the wing pods, is a microwave sounder utilizing the latest technology to achieve high sensitivity and accuracy in a relatively small package. With its three receiver systems operating with a total of 25 channels near 50 , 118 and 183 GHz, HAMSR provides temperature and water vapor sounding similar to AMSU, but has two temperature sounding bands to detect and correct for scattering from large cloud particles typically found in hurricane cumulus-convective systems. HAMSR scans across track providing a nearly complete 3-D picture of the temperature and humidity fields in a broad swath below the aircraft. These observations are key to determine the atmospheric state in and around the convective systems under investigation and are able to penetrate deeper into the rain bands than other microwave or IR sounders. The high frequency channels are also sensitive to scattering from ice formed above precipitation cells and can be used to estimate the convective intensity as well as rain rates. HAMSR participated very successfully in CAMEX-4, and calibrated brightness temperatures from a total of 47 flight hours were delivered for public distribution. For TCPS we will provide quick-look preliminary brightness temperatures in the field and, as time and resources permit, quick-look derived geophysical parameters. Afterwards we will deliver definitive calibrated brightness temperatures, followed by atmospheric profiles and other derived parameters. We will further use those and observations from other instruments to carry out hurricane related research. |
| Satellite Determination of Cloud Water and Precipitation in Tropical Cyclones During Their Entire Life Cycle
Guosheng Liu, PI, Department of Meteorology, Florida State University, Tallahassee, FL 32306-4520, liug@met.fsu.edu Cloud water and precipitation are important microphysical variables for documenting, simulating and forecasting tropical cyclones. In particular, the importance of ice-phase microphysics for simulating the strength and intensification of hurricanes is highlighted by both numerical modeling studies and observations. Although the planned 2005 field experiment can obtain detailed microphysical data for certain areas (aircraft flight legs) and during certain time periods (when flights occur), some portions of the cyclone system and some time periods during the life cycle of the storms will certainly be missed by the aircraft observations. Satellite measurements can provide complementary data to what are missed by aircraft campaigns, therefore, fill the data gaps. On one hand, satellite data can add greater areal coverage for the time period when aircraft flights are carried out. On the other hand, they can provide additional information for the same storm systems when no aircrafts are flying, so that we can document the evolution of a tropical cyclone during its entire life span (from genesis to landfall). The main goal of this project is to take this advantage of satellite observations, and through parameter retrieval and data synthesis to provide data of cloud water (liquid and ice), precipitation and other geophysical parameters during tropical cyclones’ whole life cycle. To retrieve cloud water and precipitation distributed in tropical cyclones, we plan to use satellite microwave observations. At least three microwave sensors are available during the scheduled 2005 field experiment: AMSR-E (AQUA), SSM/I and/or SSMIS (DMSP), and AMSU-B (NOAA). TRMM PR and TMI data will also be used if the satellite is still in operation during the time of experiment. Low frequency microwave (37 GHz and lower) data (SSM/I, SSMIS, AMSR-E, TMI) may be used to retrieve liquid water path. The high-frequency (150 GHz and higher) microwave channels on SSMIS and AMSU-B can be used to retrieve cloud ice water path, the moderate high frequency (~85/89 GHz) on all three sensors may be used to retrieve the amount of dense and large ice particles, and finally the combination of all channels may be used to determine precipitation. The PI has been developed algorithms for performing the above retrievals. In the proposed research, we will use the ample amount of in situ and aircraft remote sensing data obtained from the field campaigns to validate and improve our algorithms, and use the improved algorithms to retrieve cloud water and precipitation distributions within tropical cyclones. Furthermore, we propose to synthesize the satellite-data-retrieved geophysical variables archived by NASA and other data centers to build a combined dataset for the region and duration of the field experiment. The following results are anticipated from the proposed research: (1) Retrieved cloud ice water, cloud liquid water, precipitating ice, and precipitation covering the tropical cyclone and surrounding areas at a time resolution of approximately 4 times daily; (2) A synthesized dataset containing geophysical variables (both what we retrieved and those archived by various data centers); (3) Analyzed characteristics of the horizontal distribution of cloud water and precipitation in relation to tropical cyclone’s developing stages; (4) Improved cloud water and precipitation algorithms suitable for tropical cyclones. The first three items can be used by modelers for model initialization and validation purposes. The last item is a contribution to satellite remote sensing, in particular, to the retrieval of cloud ice using high-frequency microwave measurements. |
| Microwave Temperature Profiler (MTP) Support for the Tropical Cloud Systems and Processes (TCSP) Field Campaign
Michael Mahoney, PI, Jet Propulsion Laboratory, Michael.J.Mahoney@jpl.nasa.gov We propose to fly a JPL Microwave Temperature Profiler (MTP) on the NASA ER-2 during the Tropical Cloud Systems and Processes (TCSP) field campaign. MTPs passively measure the mesoscale temperature field about an aircraft's flight level, they are light-weight, they occupy locations on the aircraft not normally used by other instruments, they can run unattended, and they make measurements at microwave frequencies which are little affected by the presence of clouds. More importantly, they have an enviable performance record on nearly 700 flights (totaling 4000 flight hours) over two decades of airborne atmospheric research. The MTP measures a temperature profile [T(z)] through the atmosphere, which is a required measurement on both the TCSP upper atmospheric remote sensing platform. Implicit in the measurement of T(z) is the determination of the tropopause height, which will be important for determining the meteorological context for the other in situ and remote sensing measurements. T(z) is also required to initialize numerical weather models, and to understand the differences between model predictions and actual measurements. The MTP mesoscale temperature measurements will allow absolute humidity measurements to be converted to accurate relative humidity determinations, which is important for determining the atmosphere's saturation state. Finally, MTP data will be able to contribute to the validation of satellite temperature measurements, such on as Aqua/AIRS and Aura/MLS, /HIRDLS and /TES, especially in non-clear sky conditions. |
| The Role of Microphysical Processes in Hurricane Genesis and Evolution: Studies Using Mesoscale Models and In-Situ and Remote Sensing Observations of Clouds
Greg McFarquhar, PI, Dept. of Atmospheric Sciences, University of Illinois Urbana-Champaign, 105 S. Gregory Street, Urbana, IL 61801-3070, mcfarq@atmos.uiuc.edu Brian Jewett, Co-PI, Dept. of Atmospheric Sciences, University of Illinois Urbana-Champaign, 105 S. Gregory Street, Urbana, IL 61801-3070, jewett@atmos.uiuc.edu Matt Gilmore, Co-PI, Dept. of Atmospheric Sciences, University of Illinois Urbana-Champaign, 105 S. Gregory Street, Urbana, IL 61801-3070, gilmore@atmos.uiuc.edu Eric Schneider, Student Assistant, Dept. of Atmospheric Sciences, University of Illinois Urbana-Champaign, 105 S. Gregory Street, Urbana, IL 61801-3070, eschneid@atmos.uiuc.edu Jerry Straka, Consultant, School of Meteorology, University of Oklahoma, jstraka@ou.edu We are investigating mechanisms by which cloud-scale processes (e.g., riming, aggregation, melting, evaporation and sublimation) that occur in tropical disturbances influence whether disturbances develop into hurricanes, and how these processes affect the intensity of hurricanes that may develop. TCSP field observations (e.g., AMPR, EDOP), satellite retrievals, and models with state-of-the-art representations of microphysical processes are being used in this investigation. Fine-resolution (1 to 2 km) simulations of tropical cyclones, covering the genesis stage, will be conducted with the weather research and forecasting (WRF) model using the 12-category (2 liquid, 10 ice) Straka and Mansell 10-ICE microphysical package. This package has been designed to represent the range of microphysical processes in both convective and stratiform storms with minimal parameter tuning. We will simulate storms observed during the Convection and Moisture Experiment-4 (CAMEX-4) and those to be observed during the Tropical Cloud Systems and Processes (TCSP) experiment to improve our understanding of tropical cyclone genesis and intensity. |
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Analysis of Multi-Wavelength Radar Data Robert Meneghini, PI, NASA Goddard Space Flight Center, Code 614.6, Instrument Sciences Branch, Greenbelt, MD 20771-0001, 301-614-5652, FAX: 301-614-5558, Robert.Meneghini-1@nasa.gov Liang Liao, Co-I, Goddard Earth Sciences and Technology Center-Caelum, NASA Goddard Space Flight Center, Code 614.6, Instrument Sciences Branch, 301-614-5718, FAX: 301-614-5558, Greenbelt, MD 20771-0001, lliao@neptune.gsfc.nasa.gov A number of analysis tools have been developed and tested with data from a dual-wavelength airborne radar-radiometer and data from the TRMM Precipitation Radar (PR). These tools can be divided into those that provide estimates of the large-scale properties of the scattering medium such as liquid water content and path-integrated attenuation and those that are used to estimate microphysical parameters such as number concentration and median-mass diameter of the particle size distribution. An estimate of path-integrated attenuation (PIA) has been shown to be particularly important for any attenuating-wavelength radar analysis in that it provides a constraint that yields fairly robust high resolution estimates of water content or microphysical parameters. Although dual-wavelength retrievals of rain and snow size distributions have been shown to be reasonably accurate they are, nevertheless, subject to errors caused by cloud water and unknown quantities such as the dielectric constant of melting particles. The former problem can be resolved in part by adding radiometric data to the radar data; some progress on the latter problem has been made by numerically calculating the effective dielectric constant of ice-water particles as a function of the electromagnetic wavelength and the radial distribution of water within the particle. Although testing has been confined to X, Ku and Ka-band frequencies, the methods, in principle, should extend to W-band frequencies as long as multiple scattering effects can be neglected. We propose to develop these analysis tools using dual-wavelength airborne radar data that have been collected within recent years and applying them to the TCSP data sets for the purpose of deriving both large and small scale characteristics of the ice or water media. A secondary objective is to develop analysis tools for data from instruments aboard the CloudSAT and Global Precipitation Mission satellites. |
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Convection, Easterly Waves, the Intraseasonal Oscillation, and Hurricane Pre-Cursors in the East Pacific John Molinari, PI, University at Albany/SUNY, molinari@atmos.albany.edu This work addresses the following questions: (i) What factors determine whether or not a synoptic-scale disturbance in the subtropics spawns a tropical cyclone? and (ii) How, when, and where within the larger scale disturbance do tropical cyclones form? The variation (other than diurnal) of cumulus convection in Central America and the eastern Pacific region of study is dominated by two phenomena: easterly waves and the slowly-evolving, large-scale Madden-Julian Oscillation (MJO). Tropical cyclone formation occurs within easterly waves, but is modulated by the MJO. What remains uncertain, and will be investigated in the proposed work, is how easterly waves evolve as they move from the Caribbean to the east Pacific, how tropical cyclones form within waves, and how the MJO phase encourages and discourages the process. Use will be made of satellite information, especially vertically integrated moisture from the AQUA satellite, to track and describe the waves, and in situ data to describe the development of tropical cyclone pre-cursors. The proposed work emphasizes the structure and evolution of hurricane pre-cursor disturbances rather than of tropical cyclones per se. Nevertheless, many of the same factors – convection, vertical wind shear, and organization of multiple vortices – are likely to be important. |
| Evaluating and Improving Microphysical Parameterizations for Hurricane Lifecycle Studies
Robert Rogers, PI, NOAA/AOML Hurricane Research Division, Robert.Rogers@noaa.gov The primary objective of the work proposed here is to improve the understanding and prediction of tropical cyclone genesis, intensity change, and rainfall by evaluating and improving microphysical parameterization schemes in simulations of tropical cyclones at all stages of their lifecycle. These investigations will be carried out by comparing high-resolution numerical simulations of incipient and mature tropical cyclones with in situ and remotely-sensed data gathered by the NOAA P-3’s and NASA ER-2 aircraft collected as a part of the TCSP field program. Current bulk ice microphysical parameterization schemes have been used in high-resolution simulations and compared with observations from mature tropical cyclones. The current proposal seeks to evaluate the performance of these parameterization schemes for weak or incipient tropical cyclones by addressing the following questions: Mature and incipient systems have differences that span a variety of scales, from the mesoscale to the convective scale and the microscale. These differences highlight the importance of having a microphysical parameterization scheme robust enough to adapt to the different environments. The evaluations proposed here will be critical in assessing the robustness of current microphysical schemes, suggesting ways for improving them, and implementing them into the new operational models. The performance of the simulations will be evaluated by two methods: 1) comparing the structural features and statistical distributions of hydrometeor mixing ratio, reflectivity, and vertical motion with microphysical probe measurements from aircraft measurements (NOAA P-3’s) and Doppler radar measurements from the NOAA P-3’s and NASA ER-2; and 2) calculating budgets of water mass from observations and simulations of tropical cyclogenesis and comparing them against budgets from mature storms to document differences between observations and simulations at different stages in the systems’ lifecycle. Furthermore, improved estimates of hydrometeor fall speeds will be possible from coincident measurements of hydrometeors from the P-3’s and ER-2. Drs. Rogers (NOAA/AOML) and Chen (UM/RSMAS) will perform the simulations and oversee data collection from the NOAA P-3’s, Dr. A. Heymsfield (NCAR) will collect microphysical data from the NOAA P-3, and Dr. G. Heymsfield (NASA/GSFC) will collect Doppler radar data from the NASA ER-2. Such measurements and comparisons with the simulations will lead to the identification of biases in the simulations and point to suggested improvements in the schemes. These improvements will improve the specification of latent heating magnitude and distribution, which will improve forecasts of tropical cyclone genesis, intensity change, and rainfall. |
| An Analysis of Ozone and Water Vapor in the Upper Troposphere and Lower Stratosphere Associated With Intensification of Tropical Cyclones
Karen H. Rosenlof, PI, NOAA Aeronomy Laboratory and CIRES, University of Colorado, R/AL6, 325 Broadway, Boulder, CO 80305, Karen.H.Rosenlof@noaa.gov Eric A. Ray, Co-I, NOAA Aeronomy Laboratory, R/AL6, 325 Broadway, Boulder, CO 80305, Eric.Ray@noaa.gov We propose to use Atmospheric Infrared Sounder (AIRS) and in situ O3 and water vapor measurements in the tropical and subtropical upper troposphere and lower stratosphere (UT/LS) to investigate the conditions under which tropical cyclones intensify. Ozone and water vapor measurements can be used as indicators of stratosphere-troposphere exchange, which may influence tropical storm intensification through modification of the radiative balance of the UT. AIRS provides unique vertical profiles of O3 and water vapor in the UT/LS over the entire globe each day. We will perform a statistical analysis of these trace gases in the region of each tropical cyclone during the intensification or de-intensification period for all storms from 2002, when the AIRS instrument began taking data, to the present. We will also use in situ aircraft trace gas measurements, when available, to observe finer scale details of tracer distributions near tropical storms. Proposal objectives: We will initially do a composite analysis of AIRS O3 and water vapor mixing ratios at several levels in the UT/LS in the vicinity of tropical cyclones. The composite study will encompass tropical cyclones from September 2002-present around the globe. The main purpose of the composite will be to try to determine whether there is a consistent signal in O3 and water vapor in intensifying versus de-intensifying cyclones at any level in the UT/LS. If a consistent tracer signal is found then we will attempt to produce a predictive capability for cyclone intensification using the AIRS data. The skill of the AIRS prediction will be compared to currently available prediction methods [e.g. DeMaria et al, 1999]. |
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High- Resolution Cloud-System Simulations for Field-Phase Support and Investigation of Tropical-Storm Genesis Chris Snyder, PI, NCAR/MMM, PO Box 3000, Boulder CO, 80307-3000, chriss@ucar.edu Chris Davis, Co-I, NCAR/MMM, PO Box 3000, Boulder CO, 80307-3000, cdavis@ucar.edu We plan to examine the dynamics of tropical cyclone formation using the Weather Research and Forecasting model and ensemble-based data assimilation techniques. Our objectives are 1) to understand the initiation of mature convective systems and their transformation to warm-core systems and 2) to evaluate the potential of ensemble-based assimilation for tropical cyclones and remotely sensed observations. We will conduct real-time high-resolution simulations to support the TCSP field phase and to provide an initial set of simulations for investigation. |
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Numerical Studies of Tropical Cyclones During TCSP Da-Lin Zhang, PI, Department of Atmospheric and Oceanic Science, University of Maryland, dalin@atmos.umd.edu Although there have been limited modeling studies of tropical cyclogenesis in the past decades, little work has been done to investigate the multiscale structures and medium-range evolution of tropical cyclogenesis from convective “hot towers” to intense hurricanes. Thus, the goal of the proposed research is to address the following four questions: • To what extent satellite (e.g., AMSU, QuickSCATT and SSM/I) and airborne (e.g., dropwindsonde) observations, after mixing with the operational analysis, could improve the initial conditions of tropical disturbances for hurricane forecasts? The above questions will be addressed using 5-6 day cloud-resolving model simulations of tropical cyclogenesis that occurs during NASA’s field experiment on Tropical Cloud Systems and Processes (TCSP). They will be conducted using the Weather Research and Forecast (WRF) model with the finest grid size of 2 km. Both satellite and airborne observations will be used to better define the initial conditions of tropical disturbances. Various Hovmöller diagrams and budget calculations will be used to investigate (i) the upscale growth of convectively generated vortices (in terms of PV) to the cyclone-scale intensifying flows through axi-symmetrization processes; (ii) the thermodynamic transformation of lower-tropospheric cold anomalies to warm cores during the genesis; (iii) mesoscale organization of deep convection and vortical flows; (iv) the suppressing and stimulating roles of vertical wind shear and midlevel troughs, respectively, as well as their relative significance in tropical cyclogenesis ; and (v) the processes leading to different deepening rates (e.g., 1 - 2 hPa day-1 vs. 1 hPa hr-1) between the initial genesis and hurricane stages. Finally, several sensitivity similations will be performed to examine the roles of air-sea interaction, cloud-radiation interaction, vertical wind shear, midlevel troughs as well as the boundary-layer and cloud microphysics processes in determining the track, intensity, precipitation and inner-core structures of the storms. The proposed tasks are consistent with the major objectives of NASA’s TCSP, and they are also complementary to the goals of the U.S. Weather Research Program. Successful completion of this project will provide a better understanding of the processes leading to tropical cyclogenesis, and help gain insight into different inner-core flow characteristics of tropcial storms during the lifecycle from the genesis to hurricane stages. Satisfying results will benifit directly the future operational hurricane forecasts using the WRF model. |
| Properties of convective clouds over tropical oceans: How they may influence tropical cyclogenesis, and the production of cirrus in the tropical tropopause layer
Edward J. Zipser, PI, Dept. of Meteorology, University of Utah Zhaoxia Pu, Co-PI, Dept. of Meteorology, University of Utah Collaborators: Krueger, Garrett, Braun, Montgomery, A.Heymsfield, G. Heymsfield
The field program proposed under TCSP in 2005 is an excellent opportunity to quantify our knowledge of the properties of convective clouds through validation of remote sensing by aircraft and satellite with model experiments and direct sampling. Tropical waves pass through the area on average every 4 days, some intensifying into tropical cyclones, some not, essentially guaranteeing that both types will be sampled. At the same time, most convective systems will be producing anvil cirrus, sometimes near the tropopause, sometimes not, sometimes spreading over large areas, some not. The PI proposes full participation in the 2005 field program, as a deputy project scientist (or some analogous role). His highest priority would be to facilitate the difficult tasks of close coordination of the NASA aircraft with the turboprop fleet operating from Acapulco. The hypotheses concerning the evolution of the mesoscale vorticity field through the action of convective bursts (whether vortical or not) requires careful attention to ER-2 and DC-8 flight tracks and dropsondes, coordinated with the NOAA and NRL P3s. Collaboration with many others is essential. Data analysis from past and future field programs requires working with A. and G. Heymsfield and many others. Cloud and mesoscale model experiments with Pu, Krueger, Braun, and Montgomery will include updated microphysics and radiative transfer codes, to relate vertical velocity to simulated and observed radar profiles, microwave radiances, simulated and observed overshooting tops, anvil cirrus heights, and OLR. The models are an important link between aircraft case studies and global remote sensing. This effort is approximately 75 percent tropical cyclones and 25 percent cirrus anvils. |
