OMI Cloud-Slicing Free Tropospheric Nitrogen Dioxide (NO2) Seasonal Climatology Map

Free-tropospheric NO2 VMR is obtained by applying a cloud-slicing technique to data from the Ozone Monitoring Instrument (OMI) on the Aura satellite. We collect OMI rotational Raman (OMCLDRR) cloud scene pressure and NO2 column (OMNO2) in each grid box of 8 degree (longitude) x 6 degree (latitude) from a single orbit for the linear fit. In a cloudy scene (cloud radiance fraction > 0.9), the slope of the NO2 column versus the cloud scene pressure is proportional to the NO2 VMR in the grid box. We average the VMR measurements obtained in each grid box during each 3-month season to produce the NO2 VMR climatology.