Detection of pollution outflow from Mexico City using CALIPSO lidar measurements

- CALIPSO lidar measurements capture pollution outflow from Mexico City.
- High depolarization ratios indicate mixing of pollution with dust.
- Outflow amounts possibly reach several hundred tons in a day.

We present the evidence of regional scale outflow of particulate pollution from Mexico City using measurements from the space borne CALIPSO lidar. The vertically resolved results are presented for winter months when the large scale biomass burning from nearby areas is minimized, and the aerosol loading is dominated by anthropogenic outflow from the city. The particulate depolarization ratio in the outflowing plume has high values and reflects the influence of mixing of the urban pollution with the ubiquitous dust around the city. This is consistent with the results from previous field campaigns in the city and leads to polluted dust being the dominant aerosol subtype as identified by the CALIPSO algorithm. A first order estimate of the mass flux on two episodes using the aerosol extinction profiles from CALIPSO indicates outflow of several hundred tons per day.