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Elevated NO2 signatures over the Northeast US

By Scott Bachmeier •

TROPOMI NO2 concentration [click to enlarge]

TROPOMI NO2 concentration (credit: Bob Carp, SSEC) [click to enlarge]

High temperatures (along with high dewpoints) prompted the issuance of Excessive Heat Warnings across much of the Northeast US on 19 July 2019. Under such conditions, surface NO2 concentrations in densely-populated urban areas often become elevated (primarily driven by emissions from motor vehicle exhaust, along with secondary sources such as coal-fired power plants and manufacturing / food processing industrial sources) — the high temperatures accelerate chemical reactions that form pollutants. The TROPOMI instrument detected plumes of elevated NO2 extending downwind (to the northeast) of major cities such as Philadelphia, New York City and Boston (above). The data are displayed using McIDAS-V.

A closer view centered on New York City is shown below.

TROPOMI NO2 concentration [click to enlarge]

TROPOMI NO2 concentration (credit: Bob Carp, SSEC) [click to enlarge]

The Aqua MODIS Land Surface Temperature product around that time (below) revealed LST values in the 100-110ºF range across the New York City and Boston areas, where the daily maximum surface air temperatures were 95ºF and 93ªF, respectively.

Aqua MODIS Land Surface Temperature, with plots of daily maximum surface air temperatures [click to enlarge]

Aqua MODIS Land Surface Temperature, with plots of daily maximum surface air temperatures [click to enlarge]

Categories: Air quality, Aqua, McIDAS-V, MODIS