Robert L. de Zafra ITPA Student Symposium
The symposium will be an all-day event, and will be held at the Wang Center on the Stony Brook University campus, in Room 103. The accomodations involve a modest size conference room equipped with a computer and digital projector. All presentations will be loaded onto the computer prior to the symposium. Breakfast and lunch, along with snacks will be provided.
Background and Objectives
The purpose of this symposium is to: 1) provide a formal and regular mechanism for ITPA graduate students to share their research interests and activities with other students and the faculty, 2) provide a forum for ITPA graduate students to practice their presentation skills in a more formal seminar / symposium setting, 3) provide a convenient and exciting way to meet course (i.e. OCN 694) and graduation (i.e. annual reviews) requirements, and 4) honor one of ITPA’s most eminent professors – one that has played a substantial role in ITPA’s formation and development.
Submission Information, Requirements and Deadlines
All ITPA graduate students are required to attend and make a presentation. This requirement will only be waived upon the approval of three ITPA faculty, one of which must be your advisor/counselor.
Each student will prepare and deliver a 15 minute oral presentation of his/her current research interests and/or activities. For students already engaged a specific thesis topic, the expectation is that you will present current progress and challenges associated with your research. For students who have yet to identify their thesis topic (e.g., 1st year students), the recommendation is that you present a research report on an area of current research interest. In either case, please consult with your advisor/counselor.
Your deadlines are as follows:
February 28: Title of your presentation
March 31: Abstract of your presentation (>= 1 paragraph & <= 1 page)
April 14: PowerPoint file – the required format
Schedule
8:45-9:15 : Continental Breakfast
9:15-9:25 : Opening Remarks: David Conover, Dean and Director, MSRC
9:25-9:30 : Logistics: Minghua Zhang, Director, ITPA
9:30-10:30 : MODELING STUDIES AND TECHNIQUES – MODERATOR: M. ZHANG
Y. Lin: Cloud microphysics, how far can we go?
S. Lucas: MJO: A possible initiator of El Niño? A Model Study Approach
D. Narayanan: Applications and Usage of A Spherical Geodesic Grid
H. Song: Application of adjoint model
10:30-10:45 : Morning Break
10:45-11:45 : REGIONAL STUDIES AND WEATHER FORECASTING – MODERATOR: B. COLLE
M. Jones: Implementation and Evaluation of a Short-Range Mesoscale Ensembling System over Northeast United States
J. Olson: Idealized Simulations of Frontal Interaction with US West Coast Topography
J. Wu: Validation of Winter Season Frontal Clouds Simulated by the WRF Model
X. Yang: The split jet in Southern Hemisphere winter season
11:45: Assemble for Group Photograph
12:00-1:30 : Lunch and Presentation on Historical Perspective of ITPA
1:30-2:15 : CLIMATE VARIATIONS – MODERATOR: S. LIESS
J. Lee: Solar Cycle, the QBO, the Icelandic Low
D. Myers: Some aspects of low frequency rectification of the Madden-Julian Oscillation
Y. Li: Review and Analysis on Double Intertropical Convergence Zones and South Pacific Convergence Zone
H. Teich: Regional and global response of cloud feedback associated with strengthening of tropical circulation in the 1990’s
T. Zhou: Tropical Upwelling in the Stratosphere
2:15-3:35 : Afternoon Break and Seminar, Wang Center, Lecture Hall 2
Dr. Robert Gagosian, Director, Woods Hole Oceanographic Institution, “Can Global Warming Trigger a Big Chill?”
3:35-4:35 : AIR-SEA FLUXES AND OTHER – MODERATOR: S. HAMEED
T. Baggett: A Fifty-Year Time Series of Heat and Momentum Fluxes over Long Island Sound
Y. Guo: The Relationship between the Surface Wind and the CO2 Flux in Winter Season
F. Bakalian: The escape of heavy atoms from the martian atmosphere
J. Zheng: Development of a chemiluminescence method for gas phase HO2 detection in the troposphere
4:35-4:50 : Concluding Remarks
Presentations
T. Baggett: A Fifty-Year Time Series of Heat and Momentum Fluxes over Long Island Sound
Abstract: At present there does not exist a continuous record of heat and momentum fluxes over the Long Island Sound. Using the available data from hourly airport observations, observations of downward solar radiation, monthly sea surface temperature, and a flux model can provide an estimate of fluxes. The LaGuardia airport observations extend back for over fifty years with some data outages that must be approximated. The solar flux observations are only available for the last 25 years, but an estimate can be made based on the relationship between the clear sky solar flux and cloud observations from airport observations. The sea surface temperature is available as monthly observations, which are interpolated to hourly using harmonic analysis. Using this data as input into the COARE 3.0 model, a fifty-year, hourly time-series of heat and momentum flux over Long Island Sound can be created.
F. Bakalian: The escape of heavy atoms from the martian atmosphere
Abstract: One of the more challenging multidisciplinary problems in geophysics and atmospheric science is the study of the evolution and escape of planetary atmospheres. Geological evidence acquired from orbiter and lander missions such as Spirit and Opportunity, Mars Global Surveyor, Pathfinder, Viking I and II, and the Mariner probes appear to suggest that the Martian atmosphere was a much thicker and hospitable environment, capable of supporting flood basins, and ancient fluvial channels about 3.8 billion years ago. Quantifying the nonthermal escape of heavy species from the present atmosphere is therefor a crucial component in reconstructing the ancient Martian thermosphere. Traditionally, the escape of atoms from an atmosphere was modeled by assuming a critical level above which all atoms with energies greater than the escape energy and with velocity vectors pointed in the upward hemisphere were assumed to escape along collisionless orbits. However, this approximation does not properly describe the escape properties of heavy atoms from the Martian thermosphere. A more accurate treatment involves either solving the Boltzmann equation or applying the Monte Carlo method. Although the Monte Carlo method has been in use for centuries, it was not until the early 1970’s, when advances in computing technology allowed for quicker overall computation times, that the Monte Carlo technique gained considerable popularity and the status of a full-fledged numerical method capable of addressing the most complex applications. Presented here is a brief discussion about the general properties of the Martian thermosphere, the advancements made towards modeling the escape of heavy species from the Martian thermosphere, and some of our recent findings carried out using the Monte Carlo method.
Y. Guo:The Relationship between the Surface Wind and the CO2 Flux in Winter Season
Abstract: The global air-sea CO2 fluxes in last 45 winters (1957-2001 DJF) have been computed with gas transfer velocities calculated by using both the quadratic and cubic wind-speed dependent formula. The NCEP 6-hour wind during the 45 winters data are used. The result shows that the CO2fluxes are not sensitive to the different wind-speed dependent formula. During last nearly 50 years, global ocean CO2 from atmosphere to ocean decreases continuously. Midlatitude and high latitude Atlantic and Pacific ocean and southern hemispheric ocean( south to 20s) contribute to this decreasing, while the tropical ocean has the opposite effect. Since the increasing trend in the NCEP wind data is speculated, 50-year winter wind data from the COADS dataset are used to verify this trend (This part is not finished yet).
M. Jones: Implementation and Evaluation of a Short-Range Mesoscale Ensembling System over Northeast United States
Abstract: One approach to address the uncertainties in numerical weather prediction
(NWP) is ensemble forcasting, in which a suite of predictions is made by varying initial conditions, physical parameterizations, or a combination of both. This suite of forecasts can then be used to quantify the level of uncertainty of a given forecast period and also to produce model guidance with greater statistical significance and skill than a single deterministic forecast on average.
Ensemble forecasting efforts have traditionally been applied on the global-scale for medium-range (5-15 day) predictions, and have shown promising results. Over recent years, some groups have focused on short-range ensemble forecasting (SREF) on the mesoscale, largely examining regions over Northwest and Midwest United States. The Northeast U.S. presents a much different problem for NWP and ensembling methods than other regions where other mesoscale SREF systems have been verified. The Great Lakes, Appalachian Mountains, spatial frequency of urban centers, irregular coastline, and the Gulf Stream and Labrador Current all add to the complexity of weather prediction over the Northeast U.S.
An 18-member mesoscale SREF system was constructed using the PSU NCAR MM5 model to understand better the level and predictability of the uncertainty of lower-level metric and precipitation forecasts over Northeast U.S. The SREF system is run at 36- and 12-km grid spacing and has been designed using a combination of varied physical parameterizations (VPP) and perturbed initial conditions (PIC). 12 VPP members were made by combining three convective parameterization schemes and four planetary boundary layer schemes all initialized identically. Six PIC members use different initialization grids born from NCEP breeding and GFS analysis data and use the same model physics.
The SREF system has been operational since May 2003 and is being verified according to various sensible weather parameters across a dense network of surface and upper-air observing stations in the Northeast U.S. from May to September 2003. Significant model biases in sensible weather parameters exist in the SREF system even after ensemble averaging is applied. Several post-processing methods have been explored in order to reduce the SREF forecast bias.
A website has been developed which features 18-member complete model output, statistical products, and real-time verification calculations (http://fractus.msrc.sunysb.edu/mm5rte) in order to aide regional National Weather Service offices meet their stated goal of increasing probabilistic weather forecasting.
The development of the SREF system will be outlined, followed by some preliminary findings from the grid-point verification over Northeast U.S.
J. Lee: Solar Cycle, the QBO, the Icelandic Low
Abstract: We calculate the correlation between the 10.7 cm solar flux and the SLP, longitude, and latitude indices of Icelandic low. The variables of the Icelandic low show significant correlation with the solar activity when the variables are classified according to the phase of the quasi-Biennial Oscillation in all seasons. The time leg between the 30 mb wind and the surface condition of the Icelandic low is found to vary between 0 and 5 months. The interpretation of these results in terms of planetary waves dynamics in lower stratosphere is discussed.
Y. Li: Review and Analysis on Double Intertropical Convergence Zones and South Pacific Convergence Zone
Abstract: The ocean-atmosphere interaction in the tropics is of great importance in the earth’s climate system. The Hadley circulation is primarily driven by the intertropical convergence zone (ITCZ) and South Pacific convergence zone (SPCZ). During the boreal spring, the double ITCZ straddling the equator has been observed in some years. The climatology of the double ITCZs and SPCZ regarding the location, structure, variability and characteristics are presented and conceptual models are proposed to understand the mechanism of the double ITCZs. Satellite data are used to investigate the origin and propagation of the SPCZ and the interaction with general atmospheric circulations.
Y. Lin: Cloud microphysics,how far can we go?
Abstract: This talk overviews the cloud microphysics schemes used in numerical models, from gen-eral circulation models (GCMs) to mesoscale models. The representation of cloud microphys-ics in numerical models is still a challenge because of the wide range in spatial and temporal scales and the sophisticated processes involved.
Representative microphysics schemes in some GCMs (including GISS, CAM, ECHAM, GFDL, CSU and ECMWF) and mesoscale models (MM5 and RAMS) are briefly overviewed. It is found that these schemes are similar in terms of the basic cloud microphysics processes. Only cloud water and cloud ice are progonosed in the large scale models except CSU model. Cloud optical proporties, such as effective radius and optical depth, are more of a concern in climate models. However, in mesoscale models, more cloud condensate, including rain, snow, and hail or graupel, are prognosed. With cloud droplet number concentration predicted, dou-ble-moment scheme has been proposed for use in large scale models and mesoscale models. In addition, as the mesoscale model resolution goes down to a few kilometers, cloud systems are explicitly resolved and will require more sophisticated microphysics. While in climate models, the simulation of cloud systems combines both cumulus parameterization and micro-physics processes together.
Although more and more sophisticated cloud microphysics schemes have been developed and applied in numerical models, studies showed that these schemes still have large uncertainty. Not much verification and sensitivity of these schemes have been quantified. Preliminary verification results from IMPROVE and ARM project are promising. It is hoped that more accurate and unified cloud schemes will be approached with more comprehensive vali-dations and modifications.
S. Lucas: MJO: A possible initiator of El Niño? A Model Study Approach
Abstract: A possible initiator/regulator of the El Niño/La Niña cycle, the Madden-Julian Oscillation (MJO), is examined. The hypothesized link, from observational evidence, is that MJO wind anomalies in the western and central Pacific initiate an oceanic Kelvin wave that alters the sea surface temperatures in the eastern Pacific. However, due to the limited amount and types of surface and subsurface ocean observations a full description of thephysical mechanisms governing this system cannot be achieved. Therefore, the use of a numerical ocean model is almost essential to the understanding of the terms of the heat budget that cannot be constructed from observations. Background information with respect to current observations of the MJO-El Niño link will be given and an ocean general circulation model experiment will be discussed.
D. Myers: Some aspects of low frequency rectification of the Madden-Julian Oscillation
Abstract: While intraseasonal variability has historically been characterized in terms of wind or convection anomalies, the rich extent rich of hydrological structure associated with the MJO has recently been demonstrated. A clearer picture has emerged in which the research community’s view of the MJO has evolved to include more emphasis on the moist dynamics of these disturbances. One aspect that deserves more attention is the interplay of tropical intraseasonal variability with the mean state of the atmosphere. While it is natural to expect that the characteristics (e.g., phase speed, period, location of greatest amplitude in convective anomalies) of the tropical disturbances will vary according to changes in the background state, the details of such second-order variability are not immediately intuitive. Observations of the hydrological fields associated with the Madden-Julian Oscillation (MJO) indeed reveal that over the course of one full cycle of an MJO event, intraseasonally varying departures from the annual cycle do not sum to zero. Rather, there is a rectification onto the mean state of the atmosphere. This result implies that the background state of the atmosphere interacts with the intraseasonal variations to produce fields, which evolve with a dependence on their instantaneous amplitude.
Several aspects of the observed nonstationary behavior of the MJO will be discussed in this presentation. They include (a) characterization of the size, location, sign, and robustness of the observed rectification of rainfall and moisture, (b) a striking difference between events that appear to have longer periods versus ones with shorter periods, (c) large differences in the wind field prior to MJO events and after them, and (d) an apparent lack of great influence of ENSO on the rectification. Time permitting, other aspects may be discussed.
D. Narayanan: Applications and Usage of A Spherical Geodesic Grid
Abstract: The main purpose of this study is to find spherical triangles that cover the surface of the earth and to use these triangles as a grid system. Mathematical equations will be used to determine the locations of various points on the earth’s surface. Methods and some results will be given. In addition, an analysis of the article, “Integration of the Barotropic Vorticity Equation on a Spherical Geodesic Grid” will be presented. There will also be a concise discussion on how to test the spherical geodesic grid with the barotropic vorticity equation.
J. Olson: Idealized Simulations of Frontal Interaction with US West Coast Topography
Abstract: During the past several years a number of field studies (i.e., COAST, CALJET, PACJET) have investigated the structural evolution of fronts making landfall along the U.S. West coast during the cool season. The observational and numerical studies from these field experiments have revealed many interesting features near steep coastal terrain, such as barrier jets, enhanced upstream frontogenesis, and forward tilting frontal structures. Unfortunately, our understanding of landfalling storms is currently limited to these handful of case studies. In order to increase our understanding of the full range of frontal-terrain interactions along the U.S. West Coast, a suite of idealized simulations are necessary.
This presentation describes some preliminary results using the Penn State/NCAR mesoscale model (MM5) in an idealized configuration to investigate the structural development of the barrier jet and the interaction of landfalling systems with the barrier jet. Various idealized terrain geometries are explored to demonstrate the differing effect of inland terrain on the landfalling systems. The MM5 is nested down to 6-km grid spacing around the northern California coast in order capture the structural changes of the front approaching the coast during the 48-h simulation.
It will be shown that the idealized setup is able to capture many of the observed features of landfalling baroclinic waves such as the northward deflection of the incipient cyclone and cyclolysis during landfall, development of terrain-enhanced flow near the coast, and upstream retardation and intensification of the front approaching the coast.
H. Song: Application of adjoint model
Abstract: Adjoint model is introduced in detail. Adjoint model here refers to a mathematic tool derived from the weather simulation model. Three cases are given to illustrate the application of adjoint model. It is shown that adjoint model can improve the initial data to give a better forecast.
H. Teich: Regional and global response of cloud feedback associated with strengthening of tropical circulation in the 1990’s
Abstract: Recent studies suggest evidence for a strengthening of the tropical general circulation during the 1990’s. Tropical observations of the earth’s top of atmosphere (TOA) radiative budget during this period have shown an increase in long wave (LW) flux of approximately 5 watts per square meter and a decrease of reflected shortwave (SW) flux of 2 watts per square meter.
Studies of the 1987 El Nino event have shown that the relationship between cloud radiative forcing (CRF) and sea surface temperature (SST) differs between regional and global settings. Associated with increased sea surface temperatures in the Eastern Tropical Pacific, , regional response indicates a decrease in TOA LW flux but global response (entire Tropical Oceans) indicates an increase of TOA LW flux, consistent with strengthening of the tropical circulation.
Since the decadal trend of increase in LW flux is independent of ENSO, this study investigates whether the spatial distribution of CRR-SST relationship over decadal time scales is the same as that observed during the 1987 El Nino event. The goal of this study is to understand the physical processes associated with the decadal changes of the radiative fluxes.
J. Wu: Validation of Winter Season Frontal Clouds Simulated by the WRF Model
Abstract: Weather and Research Forecast (WRF) model is used to simulate the winter season storms both over land and over ocean. The development of the clouds and precipitation and the structure of the cyclones are examined. The simulation results are verified against the Atmospheric Radiation Measurement (ARM) program field measurements and GOES satellite cloud images. Case by case study showed that the WRF simulations are able to capture the general frontal cloud presence and position. Statistic analysis showed that WRF cloud simulation overestimate the high clouds and underestimate mid- and low clouds. Preliminary sensitivity study is conducted to examine the possible causes behind these errors in WRF model.
X. Yang: The split jet in Southern Hemisphere winter season
Abstract: A new split jet index is defined in this study, and the composites based on this index show that the cold-warm-cold tripole temperature anomaly starting from the South pole occurs in the South Pacific in association with the split-flow regimes and the non-split flow exists when the phase of the tripole temperature anomaly is reverse. The heat budget reveals that the temperature anomaly associated with the split/non-split jet is the response to the large-scale wave, not the forcing from the local diabatic heating. The local E-P flux diagnostics and the stationary wave model diagnostics both illustrate that the split/non-split jet is maintained by the vorticity flux, and the vorticity flux is dominant over the heat flux, which has the opposite effect to the split/non-split jet.
J. Zheng: Development of a chemiluminescence method for gas phase HO2 detection in the troposphere
Abstract: Hydroperoxyl Radical (HO2) is a highly reactive intermediate species that participates in photochemical processes in the troposphere. Accurate measurement of HO2 will facilitate the verification of the ozone production mechanism used by the atmospheric chemistry community. HO2is also the major source of H2O2, which is responsible for the oxidation of SO2 in cloud droplets. Here, we describe a new HO2 detection method based on flow injection analysis (FIA) with a chemiluminescence detector. Gas-phase HO2 is first scrubbed into a pH 9 borax buffer solution, then injected into a chemiluminescence detector, where HO2 and its conjugate base O2– react with MCLA, a synthetic analog of the luciferin from the crustacean Cypridina, to emit light at 465 nm. This technique shows high sensitivity (Detection Limit = 0.1 nM in liquid phase or 0.74 pptv in gas phase) and selectivity for the HO2/ O2– system. Comparing with other techniques, ours has the advantages of simplicity, low cost and ease of operation. It is especially suitable for field measurements, where space and energy resources are usually limited. A unique feature of our technique is the calibration with a radiolytic method that uses a 60Co gamma ray source to quantitatively produce stable aqueous HO2/ O2– standards. This calibration method is highly reproducible, producing an instrument response that varies less than 5% from day to day. From Aug 26 to Sep 6, 2003, we tested our instrument at the Whiteface Mountain Atmospheric Sciences Research Station, upstate New York. The station is on top of a small hill facing south. During most of the experiment, we had a persisting southern west wind, which brought aged NOx (NO + NO2) plume from Ohio power plants. Our observation showed reasonable agreement with model predicted HO2 daily profiles, which vary from a few parts per trillion in volume (pptv) upto 10 pptv. We also found HO2 did not disappear right after sunset, which indicated ozonolysis of hydrocarbons and nitrate radical chemistry can lead to HO2 nighttime production.
T. Zhou: Tropical Welling in the Stratosphere
Abstract: The magnitude and configuration of tropical upwelling of tropospheric air into the stratosphere plays an important role in determining tropical tropopause properties and in stratosphere-troposphere exchange. It is likely of great importance in understanding observed variations in stratospheric water vapor. Here, I present several idealized models of tropical upwelling, which clarify the roles of the nonlinear Hadley circulation and extratropical wave driving in determining the circulation. In particular, it is shown that the Hadley circulation and wave-driven circulation interact to determine the nature of tropical upwelling. With these models, I compare the mean meridional circulation driven by the interactions between these two effects to that circulation in the SHYHI model, showing the role of the different processes that determine the circulation. I am able to explain several features that are both observed and appear in the SKYHI model such as maximum upwelling in the summer hemisphere and the annual variation of the upwelling. One feature that is seen in both the idealized models and the SKYHI model is equatorial downwelling in boreal summer. This helps to explain the nature of the observed “tape recorder” in tropical stratospheric water vapor.
