Small amounts of atmospheric trace gasses such as ozone, carbon dioxide, or methane have profound effects on the amount of solar ultraviolet radiation that reaches the Earth’s surface (e.g. ozone hole), or the amount of heating in the atmosphere (e.g. greenhouse effect). Information about the chemical composition of the atmosphere is increasingly supplied by satellite instruments ( link to OAS satellite page) like OMI, MLS, TES, AIRS, IASI, SCIAMACHY, and GOME-2.  Atmospheric models (e.g. those in the Global Modeling Initiative) provide global maps and evolution of the chemical composition according to scientific understanding of chemical and transport processes.   However, imperfections remain in the understanding or representation of these processes in models.   Therefore, models tend to have errors, and these errors often accumulate as the models are run.

Data assimilation provides a methodology for combining information from a model with the information from observations in order to produce best estimate of the chemical composition of the atmosphere.   Noblis has expertise ( link to publications of I. Stajner) in the assimilation of chemical composition data, especially for ozone and carbon monoxide, into global atmospheric models.   Through a NASA grant, Noblis has worked with NASA scientists on assimilation of OMI and MLS ozone data into global models at NASA’s Global Modeling and Assimilation Office.   Noblis has investigated ways of providing a more accurate picture of ozone near the tropopause (at altitudes of ~6-10 miles), where ozone concentrations change rapidly from low tropospheric values to much higher stratospheric values, how well the ozone variability gets reproduced in that region (left panel over Richland, Washington on April 27, 2006 in the assimilated data and independent ozone sonde measurements), and how much intrusions of stratospheric ozone contribute to elevated ozone in the troposphere (see elevated ozone in the right panel near 600 hPa over Table Mountain in California on August 2, 2006).  This effort includes collaboration with scientists from Pennsylvania State University, University of Washington-Bothell, University of Wisconsin-Madison, and University of Toronto.  

Dr. I. Stajner of Noblis is serving as an Associate Editor for the Journal of Geophysical Research-Atmospheres of the American Geophysical Union, primarily in the areas of data assimilation and chemical composition and transport in the atmosphere.