Tropospheric Column Ozone

These visuals present retrieved global distribution of tropospheric column ozone from NASA's AURA spacecraft. Tropospheric ozone is close the ground and a component of pollution. This should be distinguished from high-altitude (stratospheric) ozone which shields the Earth's surface from ultraviolet radiation. Ozone measurements from the OMI and MLS instruments on board the Aura satellite are used for deriving global distributions of tropospheric column ozone (TCO). TCO is determined using the tropospheric ozone residual method which involves subtracting measurements of MLS stratospheric column ozone (SCO) from OMI total column ozone after adjusting for intercalibration differences of the two instruments using the convective-cloud differential method. The derived TCO field, which covers one complete year of mostly continuous daily measurements from January 2005 through December 2006, is used for studying the regional and global pollution on a timescale of a few days to months. MLS and OMI are two out of a total of four instruments on board the Aura spacecraft which is flown in a sunsynchronous polar orbit at 705 km altitude with a 98.2 degree inclination. The spacecraft has an equatorial crossing time of 1:45 pm (ascending node) with around 98.8 min per orbit (14.6 orbits per day on average). OMI is a nadir-scanning instrument that at visible (350-500 nm) and UV wavelength channels (UV-1: 270-314 nm; UV-2: 306-380 nm) detects backscattered solar radiance to measure column ozone. The MLS instrument is a thermal-emission microwave limb sounder that measures vertical profiles of mesospheric, stratospheric, and upper tropospheric temperature, ozone and other constituents from limb scans ahead of the Aura satellite. The MLS profile measurements are taken about 7 min before OMI views the same location during ascending (daytime) orbital tracks. These are referred as "collocated" measurements between OMI and MLS. The data shows signals due to convection, biomass burning, stratospheric influence, pollution, and transport. They are capable of capturing the spatiotemporal evolution of tropospheric column ozone. For more information see the links below:

http://www.nasa.gov/vision/earth/environment/ozone_resource_page.html

http://acdb-ext.gsfc.nasa.gov/Data_services/cloud_slice/#nd