Fall 2014

DATES: November 10-14, 2014

Instituto de Geociencias
 Dpto. Física de la Tierra, Astronomía y Astrofísica II
, Fac. de Ciencias Físicas
 Plaza de Ciencias, 1
Ciudad Universitaria 
28040 Madrid, España 




If you wish to meet with Professor González Ruoco, please contact Jason Smerdon jsmerdon@ldeo.columbia.edu

Professor González Ruoco will be giving two lectures on the LDEO Campus and one on the GISS/NASA Campus; all three lectures plus the reception are open to all.


Tuesday, November 11, 2014 - 3:00PM Monell Auditorium, Reception to Follow 

Title:  'A decade of efforts simulating the climate of the last millennium: lessons and open questions’

Abstract:  Present day climate variability and change, including recent anthropogenic warming, poses questions that cannot be answered based solely upon instrumental records. Due to its temporal proximity and the similarity of involved processes to those active in the present, the last millennium represents a valuable context for current and future climatic states and thus has the potential to improve our understanding of climatic variations from inter-annual to multi-centennial timescales. This talk will discuss some lessons resulting from a decade of progress in simulating the climate of the last millennium through the recent development of the PMIP3 Last Millennium Efforts: the use of model simulations as a surrogate for reality; the analysis of modeled and reconstructed responses to external forcing; and the comparison of reconstructed and simulated changes from global to regional scales and during some relevant periods of the last millennium.


Thursday, November 13, 2014 - 1:00PM Comer First Floor Seminar Room

Title:  'Answers blowing in the wind: characterizing wind variability from the academy to society and back'

Abstract:  The variability of the wind at regional and local spatial scales entails many interesting scientific questions related to the reliability of observations representing surface winds, to our ability to model wind fields with statistical and/or dynamical downscaling approaches or to understand the processes that provide a balance between the driving large-scale circulation and local effects like topography or thermal contributions. The very local character of (complex) topography or land use poses challenges for high resolution regional modeling and model-data comparison.  This talk will provide an account of our experience with some scientific problems in this context, with the intention of further elaborating on how scientific and academic interest can contribute to society and the specific needs of the private energy sector, and how this experience can, in turn, feedback to academic and scientific development.


Wednesday, November 12, 2014 - 11:00AM NASA/GISS - 3rd Floor Carl Codan Conference Room

Please note:   If you are not already registered, US citizens and permanent residents should send me their name if they plan to attend this talk. Unfortunately, no further applications from other foreign nationals can be processed at this stage.  Please note that you will be required to show a valid ID upon entering GISS.  This will include either a US passport OR a State issued drivers license plus another form of ID.

Title:  'Model-data comparison over the last millennium: some challenges and uncertainties’  
Abstract:  Comparisons of last millennium simulations and reconstructions constitute opportunities for learning about pre-instrumental climate variability beyond the lessons that climate simulations or reconstruction efforts can offer by themselves. Model-data comparisons provide insight about the relative roles of internal variability and external natural or anthropogenic induced changes and the processes involved. The relatively short ranges of external forcing variability within the last millennium nevertheless make these comparisons challenging and further complicated by the large uncertainties that affect both reconstructions and model simulations. This talk will provide a discourse on this issues and argue how model-data comparison exercises focused on the last millennium can improve our understanding of decadal to multi-centennial climate variability as well as contribute to our knowledge of present and future climate and/or associated projection uncertainties.


DATES: October 30, 2014; November 17 & 21, 2014

Professor, Atmospheric Sciences Program of SEES School of Earth and Environmental Science (SEES), Seoul National University, Seoul 151-742, KOREA

Director,Climate Environment System Research Center Seoul National University, Seoul 151-742, KOREA




If you wish to meet with Professor Kang, please contact Adam Sobel ahs129@columbia.edu

Professor Kang will be giving two lectures on the LDEO Campus and one on the Morningside Campus; all three lectures plus the reception are open to all.


Monday, November 17, 2014 - 3:00PM Monell Auditorium, Reception to Follow

Title: 'Atlantic influence on the tropical Pacific'  

Abstract:  The mechanisms associated with the background mean changes and the modulation of the El Niño-Southern Oscillation (ENSO) amplitude caused by the Atlantic Multi-decadal Oscillation (AMO) are investigated by using a long-term historical observational data and various types of models. The observational data for the period 1900-2013 show that the positive phase of AMO has accompanied cooling in the central tropical Pacific and weak ENSO variability and vice-versa in the negative phase. Such a relationship between the AMO and ENSO amplitude has been reported by a number of previous studies. In the present study, we demonstrate that the weakening of the ENSO amplitude during the positive phase of AMO is related to the changes of the SST cooling in the eastern and central Pacific accompanied by the easterly wind stress anomalies in the equatorial central Pacific, which were reproduced reasonably well by CGCM simulations performed with the Atlantic Ocean SST nudged perpetually with the observed SST representing the positive phase of AMO and free integration in the other ocean basins. Using a hybrid coupled model, it was determined that the mechanism associated with the weakening of the ENSO amplitude is related to the westward shift and weakening of the ENSO zonal wind stress anomalies accompanied by the westward shift of precipitation anomalies associated with the relatively cold background mean SST over the central Pacific.



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Friday, November 21, 2014 - 11:00AM Comer First Floor Seminar Room

Title: 'Essential dynamics for SST dependency of the MJO’

Abstract:  The dynamics of the Madden and Julian Oscillation (MJO) is investigated using a general circulation model (GCM), which reproduces the observed MJO reasonably well, and a simple one and half layer model with a first-baroclinic mode and a planetary boundary-layer. Several experiments made with various zonal-mean surface boundary conditions show that the meridional structure of SST and the land configuration are control factors for the propagation characteristics of the MJO. The idealized GCM experiments provide a test bed for validating existing MJO theories. The simple model shows that the instability of moist coupled Kelvin-Rossby waves, which depends on the lower-level moisture field determined by SST structure, controls the MJO properties. The fact that the simple theoretical model can reproduce the GCM results suggests that the essential dynamics of the MJO is rooted in a convectively coupled Kelvin-Rossby wave packet associated with the moisture convergence of low-level wind and the frictional moisture convergence near the surface.



Wednesday, November 12, 2014 - 11:00AM NASA/GISS - 3rd Floor Carl Codan Conference Room

Title:  "A GCM with explicit cloud microphysics for simulation of extreme precipitation frequency"


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Abstract:  The present work aims to develop a general circulation model (GCM) with improved simulation of heavy precipitation frequency by improving the representations of cloud and rain processes. GCMs with conventional convective parameterizations produce common bias in precipitation frequency: they overestimate light precipitation and underestimate heavy precipitation with respect to observed values. This frequency shift toward light precipitation is attributed here to a lack of consideration of cloud microphysical processes related to heavy precipitation. The budget study of cloud microphysical processes using a cloud-resolving model shows that the melting of graupel and accretion of cloud water by graupel and rainwater are important processes in the generation of heavy precipitation. However, those processes are not expressed explicitly in conventional GCMs with convective parameterizations. In the present study, the cloud microphysics is modified to allow its implementation into a GCM with a horizontal resolution of 50 km. The newly developed GCM, which includes explicit cloud microphysics, produces more heavy precipitation and less light precipitation than conventional GCMs, thus simulating a precipitation frequency that is closer to the observed. This study demonstrates that the GCM requires a full representation of cloud microphysics to simulate the extreme precipitation frequency realistically. It is also shown that a coarse-resolution GCM with cloud microphysics requires an additional mixing process in the lower troposphere.