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2003 Seminars at COLA
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Title: Analysis and Modeling of Weather and Climate Globally Employing Isentropic Perspectives
Speaker: Prof. Donald R. Johnson
Affiliation: University of Wisconsin
Date: January 29, 2003 at 3:30 p.m.
Abstract:

Over the past decade the UW Hybrid Isentropic Model with a discrete interface between the theta and sigma domains has been developed and utilized in a variety of studies. Early studies included assessment of accuracies in the simulation of long range transport of atmospheric properties including stratospheric tropospheric exchange of potential vorticity and proxy ozone within the Southern Hemispheric circumpolar vortex. More recent studies have focused on the development of a model with continuous transition from sigma to isentropic coordinates in the successful simulation of weather and climate. The UW Hybrid Model has also been joined with the NASA Langley chemistry model and successful experiments have been carried out in air quality simulations in support of NASA field campaigns. Underlying isentropic perspectives focusing on the accuracies of long range transport in relation to the exchange of potential vorticity, reversibility and appropriate conservation of moist entropy will be discussed and results will be presented attesting to the robust nature of simulations of weather and climate. The status of hybrid isentropic models being developed within the US atmospheric and planetary science communities will be briefly summarized.

 
Title: Potential Predictability of a Dynamical-Statistical Seasonal Prediction System
Speaker: In-Sik Kang, Director
Affiliation: Climate Environment System Research Center, Seoul National University
Date: February 21, 2003 at 2:00 p.m.
   
 
Title: A Data Assimilation Method Based on the Fokker-Planck Equation and its Application in the Tropical Oceans
Speaker: Dr. Clemente A.S. Tanajura
Affiliation: Laboratorio Nacional De Computacao Cientifica (LNCC), Brazil
Date: February 24, 2003 at 2:00 p.m.
   
 
Title: The Nonlinearity, Seasonal-Dependence of Atmospheric Response To the North Atlantic SST Tripole
Speaker: Dr. Shuanglin Li
Affiliation: NOAA/Climate Diagnostics Center Boulder, CO
Date: March 10, 2003 at 11:00 a.m.
   
 
Title: Linear instability analyses of generalized barotropic operators.
Speaker: Dr. Christos Mitas
Affiliation: University of Illinois at Urbana-Champaign
Date: March17, 2003 at 11:00 a.m.
   
 
Title: Pathways and formation of North Atlantic Deep Water
Speaker: Dr. David Bailey
Affiliation: School of Oceanography at University of Washington
Date: March 31, 2003 at 11:00 a.m.
   
 
Title: Simulating and Predicting Tropical Intraseasonal Variability
Speaker: Prof. Duane Walliser
Affiliation: Institute for Terrestrial and Planetary Atmospheres, State University of New York
Date: April 11th, 2003 at 11:00 a.m.
   
 
Title: Reconstructing The Global Atmospheric Circulation And The Hydrologic Cycle From Reduced Observations
Speaker: Prof. Lennart Bengtsson
Affiliation: MaxPlanck Institute, Hamburg, Germany and University of Reading, UK
Date: April 24, 2003 at 3:30 p.m.
   
 
Title: Stratospheric Water Vapor And The Tropical Tropopause
Speaker: Prof. Marvin Geller
Affiliation: Marine Sciences Research Center, State University of New York, Stonybrook
Date: May 12, 2003 at 3:30 p.m.
   
 
Title: Gravity Wave Parameters Derived from U.S. High Resolution Radiosonde Data
Speaker: Prof. Marvin Geller
Affiliation: Marine Sciences Research Center, State University of New York, Stonybrook
Date: May 13, 2003 at 11:00 a.m.
   
 
Title: Reducing Feedback Uncertainty in Climate Models
Speaker: Dr. Syukuro Manabe
Affiliation: Program in Atmospheric & Oceanic Sciences Princeton University, Princeton, New Jersey
Date: June 2, 2003 at 3:30 p.m.
Abstract: Using the top-of-the atmosphere fluxes of solar and terrestrial radiation obtained from the Earth Radiation Budget Experiment, this study estimates how the radiative damping of the annually varying, global mean surface temperature anomaly is altered by the feedback effect. Because of the large seasonal variation of surface temperature over continents, the annual variation of global mean surface temperature is dominated by the contribution from Northern Hemisphere with the annual range of about 3.3C. In the absence of feedback effect (e.g., the water vapor feedback), a temperature anomaly at the earth surface is damped by the planetary emission, which approximately follows the Stefan-Boltzmann's law of the blackbody radiation. Our analysis indicates, however, that the radiative damping from the top of the atmosphere is only 30% of the damping due to blackbody radiation, thereby enhancing the annual variation of global surface temperature. Using the data obtained from ERBE, we have also evaluated how the cloud feedback process alters the radiative damping of the annual variation of global surface temperature. To our surprise, we found that the cloud feedback neither amplifies nor damps the annual variation. The feedback analysis is conducted for three general circulation models, which compute explicitly the microphysical properties of cloud. It is noted that the sign and magnitude of the net effect of feedbacks in all three models is similar to those of the observed. However, the individual contributions from the terrestrial and solar components of the net feedback effect are different between the simulated and observed. Since the discrepancy disappears if the contribution from the cloud feedback were removed, we believe that it is attributable mainly to the failure of the models to simulate individually the terrestrial and solar components of the cloud feedback. The geographical distribution of the annual surface temperature variation is quite different from the simulated pattern of global warming. Nevertheless, a test such as those conducted here can yield valuable information on the systematic bias of relevant feedback processes in a climate model.
 
Title: Simulation of Younger Dryas Event: Why Did Climate Change So Abruptly?
Speaker: Dr. Syukuro Manabe
Affiliation: Program in Atmospheric & Oceanic Sciences Princeton University, Princeton, New Jersey
Date: June 3, 2003 at 3:30 p.m.
Abstract: Using a coupled ocean-atmosphere model, this study explores the physical mechanism responsible for so-called abrupt climate change such as Younger Dryas events. In response to massive fresh water discharge into northern North Atlantic over 500 years, the simulated thermohaline circulation (THC) weakens in the Atlantic Ocean, reducing surface temperature over the northern North Atlantic and surrounding regions. Upon the termination of fresh water discharge on the 500th year, the THC begins to intensify, regaining its original intensity in a few hundred years. The sudden onset and termination of fresh water induce an irregular, multi-decadal fluctuation in the THC intensity, yielding almost abrupt climate changes. A similar, but much weaker fluctuation of the THC is also evident in the control integration of the coupled model without freshwater forcing. It is accompanied by the multi-decadal fluctuation of subarctic gyre, which yields surface salinity anomaly similar to "Great Salinity Anomaly".
 
Title: Representing spatial sub-grid scale variability at the land-atmosphere interface in a GCM
Speaker: Dr. Andrea Hahmann
Affiliation: University of Arizona - Institute of Atmospheric Physics
Date: June 05, 2003 at 3:30 p.m.
 
Title: Madden Julian Oscillation: A Model Study
Speaker: Dr Rameshan Kallummal
Affiliation: Physics of Weather and Climate Section, The Abdus Salam International Center for Theoretical Physics, Trieste, Italy
Date: June 30, 2003 at 3:00 p.m.
Abstract: Simulations from a simplified Atmospheric General Circulation Model (AGCM), called SPEEDY, are examined for its ability to capture the gross features of intraseasonal variabilities (ISV), with emphasis on the Madden-Julian Oscillation (MJO), observed in the tropics. The space-time spectral distribution of ISV generated in SPEEDY and that found in observation resemble each other in many respects, when compared in terms of symmetric and antisymmetric modes of shallow water system. It is shown that slow and fast phases and timescale of simulated-MJO are also in fairly good agreement with the observation. Improvements in MJO simulations have been obtained by modifying the convection scheme in order to increase the build-up time for lower-tropospheric moisture preceding tropical convective events.
 
Title:

(1) El Nino: Buffer to climate change? (2) Regional modeling and observation based investigation of mesoscale variability of ENSO teleconnections in the Western USA

Speaker: Dr. Allen Hunt
Affiliation:  
Date: September 9, 2003 at 3:45 p.m.
 
Title: Land-Ocean-Atmospheric Interaction Associated With Coastal Earthquakes
Speaker: Dr. Ramesh P. Singh
Affiliation: Professor, Indian Institute Of Technology, Kanpur, India
Date: September 15, 2003 at 1:00 p.m.
Abstract:
Coastal earthquakes are very common throughout the world. These earthquakes bring out changes in land, ocean and atmospheric parameters. In the present talk, various land, ocean and atmospheric parameters retrieved from satellite data will be presented. The land, ocean and atmospheric parameters around the epicenter of numerous earthquakes show anomalous behavior prior to the coastal earthquakes. The interaction between land-ocean-atmosphere is found to be controlled by land and ocean parameters and location of the epicenter from the ocean. Numerous parameters deduced from satellite data over epicenter of earthquakes away from the ocean show weak interaction.
 
Title: Record Warfare in the Global System and the Next Magnitude R > 7.1 Record-setting Conflict: A Preliminary Analysis and Biospheric Implications
Speaker: Prof. Claudio Cioffi-Revilla
Affiliation: Professor, George Mason University
Date: October 20, 2003 at 2:00 p.m.
Abstract:
The long-term process of warfare involving great powers in the global system is well-documented for the past five hundred years of history (Levy 1983; Small and Singer 1983) with complete data and no missing observations. This study demonstrates the existence of a previously undetected process with exponentially increasing record values in war fatalities, or constantly increasing record magnitudes for warfare produced by the great power core of the global system. Thirteen wars since 1495 have set unprecedented battle-fatality records, not counting civilian and postwar fatalities. Based on these findings, the next record-setting war, which is now statistically overdue by several decades, is estimated to be of at least magnitude 7.35 (approximately 22.5 battle fatalities), global in scale, waged with weapons of mass destruction, and with arguably unpredictable consequences for the Earth's biosphere. Civilian and postwar casualties would significantly increase this preliminary estimate.
 
Title: The Tropical Precipitation Simulated by the NCAR Community Climate Model, Ver. 3 (CCM3) : An Evaluation based on Observations of the TRMM Satellite
Speaker: Dr. Craig Collier
Affiliation: Texas A&M University
Date: October 27, 2003 at 1:30 p.m.
Abstract:
Monthly-mean precipitation rates from an ensemble of CCM3 simulations are compared tothose computed from observations of the TRMM satellite over a 44-month period. On regional and sub-regional scales, the comparison fares well over much of the Eastern Hemisphere south of 10S and over South America. However, model - satellite differences are large in portions of Central America and the Caribbean, the southern tropical Atlantic, the northern Indian Ocean, and the western equatorial and southern tropical Pacific. Since precipitation in the Tropics is the primary source of latent energy to the general circulation, such large model - satellite differences imply large differences in the amount of latent energy released. Differences tend to be seasonally-dependent north of 10N, where model wet biases occur in realistic wet seasons or model-generated artificial wet seasons. South of 10N, the model wet biases exist throughout the year or have no recognizable pattern.
 
Title: Interactive climate chemistry modelling: Implications for recent stratospheric cooling
Speaker: Dr Elisa Manzini
Affiliation: National Institute for Geophysics and Volcanology, Bologna, ITALY
Date: November 3, 2003 at 2:00 p.m.
Abstract:
The sensitivity of the middle atmosphere circulation to ozone depletion and increase in greenhouse gases is assessed by performing multiyear simulations with a chemistryclimate model. Three simulations with fixed boundary conditions have been carried out: one simulation for the near-past (1960) and two simulations for the near-present (1990 and 2000) conditions, including changes in greenhouse gases, in total organic chlorine, and in average sea surface temperatures. Changes in ozone are simulated interactively by the coupled model. It is found that in the stratosphere, ozone decreases, and that in the Antarctic, the ozone hole develops in both the 1990 and the 2000 simulations but not in the 1960 simulation, as observed. In the Arctic lower stratosphere, a cooling in March with respect to the 1960 simulation is found only for the 2000 simulation. Wave activity emerging from the troposphere is found to be comparable in the winters of the 1960 and 2000 simulations, suggesting that ozone depletion and greenhouse gases increase contribute to the 2000 1960 March cooling in the Arctic lower stratosphere. These results therefore provide support to the interpretation that the extreme low temperatures observed in March in the last decade can arise from radiative and chemical processes, although other factors cannot be ruled out. The comparison of the 1960 and 2000 simulations shows an increase in downwelling in the mesosphere at the time of cooling in the lower stratosphere (in March in the Arctic; in October in the Antarctic). The increase in dynamical heating associated with the increased downwelling may limit the cooling and the strengthening of the lower stratospheric polar vortex from above, facilitating ozone recovery and providing a negative dynamical feedback
 
Title: Can Climate Trends be Calculated from Re-Analysis Data?
Speaker: Prof. Lennart Bengtsson
Affiliation: MaxPlanck Institute, Hamburg, Germany and University of Reading, UK
Date: November 10, 2003 at 2:00 p.m.
Abstract:
Several global quantities are computed from the ERA40 re-analysis for the period 1958-2001 and explored for trends. These are discussed in the context of changes to the global observing system. Temperature, integrated water vapour (IWV) and kinetic energy are considered. The ERA40 global mean temperature in the lower troposphere has a trend of + 0.11K per decade over the period of 1979-2001, which is slightly higher than the MSU measurements, but within the estimated error limit. For the period 1958-2001 the warming trend is 0.14 K per decade but is likely to be an artefact of changes in the observing system. When this is corrected for the warming trend is reduced to 0.10K per decade The global trend in IWV for the period 1979-2001 is + 0.36 mm per decade. This is more than what is determined from the Clausius-Clapeyron relation assuming conservation of relative humidity. It is also larger than results from free model integrations driven by the same observed sea surface temperature (SST) as used in ERA40. It is suggested that the large trend in IWV does not represent a genuine climate trend but an artefact caused by changes in the global observing system such as the use of SSM/I and more satellite soundings in later years. Recent results are in good agreement with GPs measurements. The IWV trend for the period from 1958 is still higher but reduced to + 0.16mm per decade when corrected for changes in the observing systems. Total kinetic energy shows an increasing global trend. It is strongly suggested based on assimilation experiments that this trend is also incorrect and mainly caused by the huge changes in the global observing system in 1979. When this is corrected for no significant change in global kinetic energy from 1958 onwards can be found.
 
Title: Possible influence of the anthropogenic SO2 emissionon low-level cloud properties over China
Speaker: Dr. Kazuaki Kawamoto
Affiliation: Research Institute for Humanity and Nature, Kyoto, Japan
Date: December 4, 2003 at 3:30 p.m.
Abstract:

Indirect effect by anthropogenic aerosols, that is, cloud modification caused by human activity, is one of the most uncertain factors among climate issues, as IPCC reports indicate. Since early 1980s, the energy consumption in China had increased substantially due to an economic development caused by the drastic political changeover. Under this background, the effect of human activity on low-level cloud properties (the particle size, optical depth and particle number) was explored using SO2 emission as a proxy. The cloud properties were derived from optical remote sensing using satellite sensors. As a result of comparison between annual-mean SO2 emission and cloud properties, the cloud particle size becomes smaller, on the other hand, the cloud optical depth and particle number get larger, as SO2 emission increases. These behaviors can be explained by Twomey effect due to linkage from SO2 to aerosols. Multiyear comparison between 1985 and 1995 suggests reduction of the cloud particle size and enhancement of the cloud optical depth and particle number in accordance with an increase in SO2 emission. The results obtained here would give evidence in large-scale cloud modification by anthropogenic activity over land, which was thought to be less sensitive compared to over ocean.

 
Title: Simulation and Prediction of ENSO and MJO with the New NCEP Coupled Model
Speaker: Dr. Wanqiu Wang
Affiliation: National Centers for Environmental Prediction
Date: December 9, 2003 at 3:30 p.m.