Cryospheric and Polar Processes Seminar: Amanda Lynch
Linkages between Arctic summer circulation regimes and regional sea ice anomalies
by Dr. Amanda Lynch - CIRES Visiting Fellow; Director, Institute at Brown for Environment and Society, Lindemann Distinguished Professor, Department of Earth, Environmental and Planetary Sciences, Brown University
Studies of linkages between summer atmospheric circulation patterns and the downward trend in annual Arctic sea ice minimum have suggested systematic relationships between low sea ice years and the Arctic Dipole pattern. While the first order downward trend in Arctic sea ice extent has been strong, particularly in the last few decades, departures in ice extent from year to year are typically the result of large and often partially compensating regional anomalies. In particular, the trend in open water in the Pacific sector has been both larger and more variable than the trend in the Atlantic sector, due in part to the ubiquity of Fram Strait export maintaining some measure of ice cover.
Decadal predictive skill of sea ice by earth system models is increasing rapidly. However, the challenge of sea ice predictability is no more immediate than in the quest for time-sensitive decision support for technically feasible navigation routes with enough skill and detail to predict requirements for ship class. In this context, developing new approaches for seasonal ice prediction presents an important test for our understanding of the evolving system.
This talk will present initial results that combine statistical modeling of ice and shipping costs with analysis of atmospheric circulation regimes using self organizing maps as part of an ongoing project to better understand the drivers of change on critical shipping routes in the Arctic.
CWEST Distinguished Seminar Series: Lauren E. Hay
The Center for Water, Earth Science and Technology (CWEST) presents
Hydrologic Modeling on a National Scale
by Lauren E. Hay - U.S. Geological Survey, Denver, CO
The United States Geological Survey (USGS) has developed a National Hydrologic Model (NHM) to support coordinated, comprehensive and consistent hydrologic model development, and facilitate the application of hydrologic simulations within the conterminous United States (CONUS). The NHM will provide accurate and consistent estimates of total water availability, changes in the timing and source of flow, and measures of the uncertainty of these estimates; essential elements in assessing the response of the Nation’s watersheds and ecosystems to climate and land use changes at local, regional, and national scales.
The NHM structure includes (1) a consistent geospatial fabric for modeling; (2) daily and monthly time-step models; (3) the ability to subset and aggregate models (nested models); and (4) multi-basin, multi-step, multi-objective model calibration procedures. The NHM has the ability to address issues regarding the use of measured data sets from continental scale networks (e.g. streamflow and climate) and large-scale datasets (e.g. remotely-sensed data products). Methods for large scale parameter estimation, uncertainty quantification and calibration approaches are also being investigated at the continental scale with the NHM. Current results for CONUS will be presented.