Evaluation of MERRA-2 Total columnar ozone from ground based and AIRS satellite product

In the present study, a first systematic evaluation and analysis of long-term (2009–2020) gridded datasets
$(0. 5^{\circ}\times 0.625)$
of total columnar ozone (TCO) from Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2TCO) is carried out over the Indian subcontinent. The
$\text{MERRA} -2_{\text{TCO}}$
is first validated with observed
$(\text{IMD}_{\text{TCO}})$
and then further compared with Atmospheric Infrared Sounder
$(\text{AIRS}_{\text{TCO}})$
satellite dataset. For an in-depth comparison and statistical analysis, the dataset has been segregated into seven distinct regions, i.e. Western Himalaya (WH), Northeast (NE), North Central (NC), Northwest (NW), West Peninsula India (WPI), East Peninsula India (EPI), and South Peninsula India (SPI). Descriptive statistics (NMSE, FB, R, FA2 and d) reveals significant correlation of MERRA
$-2_{\text{TCO}}$
with
$\text{IMD}_{\text{TCO}}$
over Delhi (NMSE=0.0013, FB=-0.029) and Varanasi (NMSE=0.0008, FB=-0.014) cities. Further, a comparison of
$\text{MERRA} -2_{\text{TCO}}$
with
$\text{AIRS}_{\text{TCO}}$
represents the NMSE values ranging from 0.0023-0.0047 DU and a correlation coefficient of 0.62-0.87 in different regions of India. In support of Brewer's circulation pattern, an increasing strong shift of columnar ozone from low (SPI) to high (WH) latitudinal regions in annual variation (2009–2020) is observed. Our finding indicate that the MERRA-2 ozone dataset can be effectively used for ozone air quality studies over the Indian regions and the analysis may highlight the necessity for independent, reliable, consistent, and accurate ozone observations.