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2004 Seminars at COLA
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Title: NWS Science and Technology Infusion Plan for Climate Services - Bridging Climate Research and Operations
Speaker: Dr. Jiayu Zhou
Affiliation: Climate Lead, NOAA/NWS/OST12
Date: January 20, 2004 at 3:30 p.m.
Title: Regional Effects of Climate Phenomena and the Role of Remote Sensing
Speaker: Prof. Menas Kafatos and colleagues from the Center for Earth Observations and Space Research
Affiliation: Dean, School of Computational Sciences, George Mason University
Date: March 9, 2004 at 1:00 p.m.
Abstract: Increasing appreciation has emerged that climate change impacts are not only felt at the regional and local levels but that it is at these levels that great impact may manifest on shorter timescales. Remote sensing (RS) data now have a sufficiently long time coverage (20+ years) to discern several interannual cycles and provide the beginning of verification of longer-term model predictions. Mesoscale models can benefit from the introduction of RS as B.C. and I.C. These combined efforts allow blending of what used to be distinct regimes, science vs. applications. Several regional phenomena and effects will be discussed including ENSO signatures in vegetation and hydrological data at regional to local scales; severe weather phenomena; the use of RS and mesoscale modeling for hurricanes; the connection between hurricanes and tornadoes, etc. Some examples from the CEOSR-led NASA-funded project VAccess/MAGIC will be presented. It is anticipated that the presentation will lay the groundwork for closer collaboration between COLA and climate dynamics in SCS on the one hand, with other units of SCS, CEOSR, Earth Systems and Geoinformation Sciences Program (ESGS) and CAMP.
Title: NASA GEOS-4 reanalysis: assessment and a sensitivity study.
Speaker: Dr. Shuhua Li
Affiliation: Global Modeling & Assimilation Office, NASA/GSFC
Date: March 10, 2004 at 2:30 p.m.
Title: Improving the parameterizations of soil properties and land ecosystems for modeling climate.
Speaker: Dr. Qing Liu
Affiliation: Georgia Institute of Technology
Date: March 30, 2004 at 3:30 p.m.
Title: Systematic Strategies for Stochastic Climate Models
Speaker: Dr. Andy Majda
Affiliation: Courant Institute of Mathematical Sciences
Date: April 12, 2004 at 3:30 p.m.
Title: The Role of Initial and Boundary Conditions for the Time-Space Distribution of Sub-seasonal Atmospheric Predictability
Speaker: Dr. Thomas Reichler
Affiliation: Geophysical Fluid Dynamics Laboratory Princeton University, Princeton NJ
Date: May 10, 2004 at 3:30 p.m.
Abstract: In this talk I discuss the prospects and limits of sub-seasonal (2 weeks to 2 months) atmospheric predictability. Forecasting at this time range is difficult since elements of both the weather and the climate prediction enter the problem. The basic questions of this study are: (1) How large is sub-seasonal predictability with a perfect model and perfect data; (2) how sensitive is such predictability to uncertainties in model and data; (3) which atmospheric processes are related to this predictability and the lack thereof? These questions are answered through a series of numerical experiments with an atmospheric general circulation model which was forced with different combinations of initial and boundary conditions. It is found that the atmosphere is remarkably sensitive to initial conditions on the week 3-6 forecast range. Particularly, the troposphere over Antarctica, the region over the tropical Indian Ocean, and the lower stratosphere are affected. Most of the initial condition memory is related to the persistent nature of the atmosphere in these regions, which in turn can be linked to the major modes of atmospheric variability.
Title: The Diurnal Cycle of Tropical Precipitation in a General Circulation Model
Speaker: Dr. Craig Collier
Affiliation: Texas A&M University
Date: May 12, 2004 at 2:30 p.m.
Title: Recirculation of Coastal Urban Air Pollution Under a Synoptic Scale Thermal Trough in Perth, Western Australia
Speaker: Dr. Yimin Ma
Affiliation: CAMP research group, GMU, Va
Date: May 13, 2004 at 3:30 p.m.
Title: NCAR/SCD Computer Changes
Speaker: Dr. Dick Valent
Affiliation: NCAR Scientific Computing Division
Date: May 18, 2004 at 11:00 a.m.
Title: Storm Track Predictability on Seasonal to Decadal Scales
Speaker: Dr. Gilbert P. Compo
Affiliation: Climate Diagnostic Center, Boulder, Colorado
Date: June 29, 2004 at 3:30 p.m.

This talk is concerned with estimating the predictable variations of extratropical daily weather statistics ("stormtracks") associated with global sea surface temperature (SST) changes on interannual to interdecadal scales, and its magnitude relative to the unpredictable noise. The SST-forced stormtrack signal in each northern winter in 1950-99 is estimated as the mean stormtrack anomaly in an ensemble of atmospheric general circulation model (AGCM) integrations for that winter with prescribed observed SSTs. Since the stormtrack signals cannot be derived directly from the archived monthly AGCM output, they are diagnosed from the SST-forced winter-mean 200 mb height signals using an empirical linear stormtrack model (STM). For two particular winters, the El Nino of JFM 1987 and the La Nina of JFM 1989, the stormtrack signals and noise are estimated directly, and more accurately, from additional large ensembles of AGCM integrations. The linear STM is remarkably successful at capturing the AGCM's stormtrack signal in these two winters, and is thus also suitable for estimating the signal in other winters. We find that a predictable SST-forced stormtrack signal exists in many winters, but its strength and pattern can change substantially from winter to winter. The pattern correlation of the SST-forced and observed stormtrack anomalies is high enough in the Pacific-North American sector to be of practical use. In the Euro-Atlantic region, we find much lower correlations, which we argue arise from substantial AGCM error in representing the regional response to tropical SST forcing, rather than intrinsically low predictability.

Title: Feasibility of a reanalysis using only surface data
Speaker: Dr. Gilbert P. Compo
Affiliation: Climate Diagnostic Center, Boulder, Colorado
Date: June 30, 2004 at 10:30 a.m.

Studies of climate variability and change are increasingly focused on understanding and predicting regional changes of daily weather statistics. Assessing the evidence for such variations over the last hundred years requires a daily tropospheric circulation dataset. The only available data for the early 20th century are error-riddled hand- drawn analyses of the mean sea level pressure field over the northern hemisphere. Modern data assimilation systems have the potential to improve upon these maps, but prior to 1948, there are few digitized upper-air sounding observations available for such a reanalysis. We investigate the possibility that the quantity of newly recovered surface pressure observations is sufficient to generate a useful reanalysis of at least the lower tropospheric circulation back to 1900. Surprisingly, we find that with an ensemble data assimilation system, one should be able to produce high-quality reanalyses of even the upper troposphere using only surface pressure observations.

Title: Interannual variability of the Asian-Australian monsoon
Speaker: Dr. Song Yang
Affiliation: NOAA Climate Prediction Center
Date: October 6, 2004 at 3:30 p.m.

In the presentation, the speaker will address several issues regarding the atmosphere-ocean-land processes associated with the variability of the Asian-Australian monsoon, with a focus on the seasonal-to-interannual time scales. He will discuss the problems and opportunities in studies of the monsoon in areas covering (a) general data and modeling problems, (b) interaction between monsoon and El Nino-Southern Oscillation, (c) influence of land surface process on monsoon, (d) importance of extra-tropical atmospheric process, (e) impact of local sea surface temperatures, and (f) the role of the Indian Ocean in Asian-Australian monsoon climate. He will also provide evidence of the active role of Asian monsoon in the variability of global climate.

Title: On the Use of Dimensioned Measures of Average Error in Comparing Climate Fields
Speaker: Prof. Cort J. Willmott, co-authors: Kenji Matsuura and Michelle Johnson
Affiliation: Center for Climatic Research, Department of Geography, University of Delaware
Date: November 1, 2004 at 3:30 p.m.

The relative abilities of three, dimensioned error statistics---the root-mean-square error (RMSE), the mean absolute error (MAE) and the mean bias error (MBE)---to describe average error or difference between climate fields are examined. Three examples are used to illustrate our points. The first example is drawn from a recent comparison of gridded, global precipitation data sets that appeared in the Journal of Climate (Fekete et al. 2004). Our second example is constructed (by us) from climatologically averaged weather-station air temperatures, which we alternately interpolate spatially (grid) using two interpolation procedures. Within a third example, we use MAE to evaluate the relationships between grid resolution and spatial resolution error for monthly precipitation within the Amazon Basin. The RMSE and its square, the mean-square error (MSE), are of particular interest, because they are the most widely reported average-error measures, and they are fundamentally flawed. It (RMSE) is an inappropriate measure of average error because it is a function of three characteristics of a set of errors, rather than of one (the average error). Our findings indicate that MAE and MBE are natural measures of average error, and that (unlike RMSE) they are unambiguous.