A comparison of carbon monoxide retrievals between the MOPITT satellite and Canadian High-Arctic ground-based NDACC and TCCON FTIR measurements

• Main Authors: Jalali, Ali, Walker, Kaley A., Strong, Kimberly, Buchholz, Rebecca R., Deeter, Merritt N., Wunch, Debra, Roche, Sébastien, Wizenberg, Tyler, Lutsch, Erik, McGee, Erin, Worden, Helen M., Fogal, Pierre F., Drummond, James R.
• Format: Text
• Language: English
• Published: 2022
• Subjects: Arctic; Canada; Eureka; Nunavut
• Online Access: https://doi.org/10.5194/amt-2022-68; https://amt.copernicus.org/preprints/amt-2022-68/

Measurements of Pollution in the Troposphere (MOPITT) is an instrument on NASA’s Terra satellite that has measured tropospheric carbon monoxide (CO) from early 2000 to the present day. Validation of data from satellite instruments like MOPITT is often conducted using ground-based measurements to ensure the continued accuracy of the space-based instrument’s measurements and its scientific results. Previous MOPITT validation studies generally found a larger bias in the MOPITT data poleward of 60 °N. In this study, we use data from 2006 to 2019 from the Bruker IFS 125HR Fourier Transform Infrared spectrometer (FTIR) located at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Nunavut, Canada to validate the MOPITT Version 8 retrievals. These comparisons utilize mid- and near-infrared FTIR measurements made as part of the Network for the Detection for Atmospheric Composition Change (NDACC) and the Total Carbon Column Observing Network (TCCON), respectively. All MOPITT version 8 retrievals within a 1° radius from the PEARL Ridge Laboratory and within a 24-hour time interval are used in this validation study. MOPITT retrieval products include those from the near-infrared (NIR) channel, the thermal infrared (TIR) channel, and a joint product from the thermal and near-infrared (TIR-NIR) channels. Each channel’s detector has four pixels. We calculated the MOPITT pixel-to-pixel biases for each pixel, which were found to vary based on the season and surface type (land or water). The systematic bias for pixel 1 over land is larger than that for other pixels, which can reach up to 20 ppb. We use a small-region approximation method to find filtering criteria. We then apply the filters to the MOPITT dataset to minimize the MOPITT pixel bias and the number of outliers in the dataset. The sensitivity of each MOPITT pixel and each product is examined over the Canadian high Arctic. We then follow the methodologies recommended by NDACC and TCCON for the comparison between the FTIR and satellite total column ...