Research Projects

Satellite based UV-visible spectroscopy measuring NO2 is now routine and prospects for continuing observations are excellent. The contractor performed an extensive analysis of the application of satellite measurements to an understanding of spatial and temporal patterns of NO2 in California. The analysis confirms that trends observed from space are extremely accurate?inter-annual variations as small as 1-2% are evident in a time series. The contractor finds that interpretation of the satellite record requires attention to both the spatial resolution of the primary observations and the model used to interpret those observations. They note that the spatial pattern of the satellite observations from the OMI instrument varies in a 16 day sequence, so that long term averages can be constructed that have higher resolution than the original observations. This spatial pattern is sensitive to emissions, meteorology and chemistry and is one of the most informative tests we have available of the accuracy of the components of current air quality models. They describe application and evaluation of the satellite observations with attention to trends in major air districts in California and with an eye to new strategies for integrating satellite observations into the air quality management system.