We describe the new version 3.0 NASA Ozone Monitoring
Instrument (OMI) standard nitrogen dioxide (NO
2) products (SPv3). The
products and documentation are publicly available from the NASA Goddard Earth
Sciences Data and Information Services Center
(
https://disc.gsfc.nasa.gov/datasets/OMNO2_V003/summary/). The major
improvements include (1) a new spectral fitting algorithm for NO
2 slant
column density (SCD) retrieval and (2) higher-resolution (1° latitude
and 1.25° longitude) a priori NO
2 and temperature profiles
from the Global Modeling Initiative (GMI) chemistry–transport model with
yearly varying emissions to calculate air mass factors (AMFs) required to
convert SCDs into vertical column densities (VCDs). The new SCDs are
systematically lower (by ∼ 10–40 %) than previous, version 2,
estimates. Most of this reduction in SCDs is propagated into stratospheric
VCDs. Tropospheric NO
2 VCDs are also reduced over polluted areas,
especially over western Europe, the eastern US, and eastern China. Initial
evaluation over unpolluted areas shows that the new SPv3 products agree
better with independent satellite- and ground-based Fourier transform infrared (FTIR) measurements.
However, further evaluation of tropospheric VCDs is needed over polluted
areas, where the increased spatial resolution and more refined AMF estimates
may lead to better characterization of pollution hot spots.