Nitrogen dioxide and formaldehyde measurements from the GEOstationary Coastal and Air Pollution Events (GEO-CAPE) Airborne Simulator over Houston, Texas

Abstract

Abstract. The GEOstationary Coastal and Air Pollution Events (GEO-CAPE) Airborne Simulator (GCAS) was developed in support of NASA's decadal survey GEO-CAPE geostationary satellite mission. GCAS is an airborne pushbroom remote sensing instrument, consisting of two channels which make hyperspectral measurements in the ultraviolet/visible (optimized for air quality observations) and the visible/near-infrared (optimized for ocean color observations). The GCAS instrument participated in its first intensive field campaign during the Deriving Information on Surface Conditions from Column and Ver- Texas. We present GCAS trace gas retrievals of nitrogen dioxide (NO 2 ) and formaldehyde (CH 2 O), and compare these results with trace gas columns derived from coincident in situ profile measurements of NO 2 and CH 2 O made by instruments on a P-3B aircraft, and with NO 2 observations from ground-based Pandora spectrometers operating in direct sun and scattered light 10 modes. GCAS tropospheric column measurements correlate well spatially and temporally with columns estimated from the P-3B measurements for both NO 2 (r

Revisiting the effectiveness of HCHO/NO2 ratios for inferring ozone sensitivity to its precursors using high resolution airborne remote sensing observations in a high ozone episode during the KORUS-AQ campaign

“…However, GeoTASO HCHO/NO2 ratios tend to be higher than those of DC-8. A number of factors contribute to the disagreement between two datasets: i) the accuracy in the retrievals [Nowlan et al, 2016;Nowlan et al, 2018;Lamsal et al, 2017] can directly contaminate HCHO/NO2 column, ii) the assumption of the effective vertical diffusion mechanism within the mixed layer should not rule out the impact of the free troposphere on the magnitude of column, and iii) the spatial heterogeneity in the observations inevitably leads to some degree of disagreements.…”

“…The advantage of focusing on the KORUS-AQ campaign period is the availability of a large suite of observations including those from airborne remote sensing [Nowlan et al, 2016;Nowlan et al, 2018;Souri et al, 2018], and in situ aircraft DC-8 observations. Particularly, we will use NO2 and HCHO observations from the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) sensor.…”

Identification of Sea Breeze Recirculation and Its Effects on Ozone in Houston, TX, During DISCOVER‐AQ 2013

“…The B‐200 aircraft equipped with GEOstationary Coastal and Air Pollution Events (GEO‐CAPE) Airborne Simulator (GCAS) instrument measured NO 2 column densities on 11 days with four flight loops each day. Details of the data and retrieval algorithm can be found in Nowlan et al (2018).…”

Space‐Based Observational Constraints on NO2 Air Pollution Inequality From Diesel Traffic in Major US Cities

“…In Demetillo et al (2020), we conducted a detailed evaluation of the use of TROPOMI observations to describe intra-urban NO 2 disparities, demonstrating that TROPOMI was indeed well-positioned to inform multiple aspects of NO 2 inequality research in Houston, Texas. We used fine spatial resolution (250 × 500 m 2 ) airborne NO 2 remote sensing measurements from the GEOstationary Coastal and Air Pollution Events Airborne Simulator (GCAS) as a standard (Nowlan et al, 2018), showing that TROPOMI, oversampled to 0.01° × 0.01° using the physics-based algorithm employed here, resolved equivalent NO 2 relative inequalities as GCAS. We assessed the effects of observational uncertainties, retrieval biases, and time averaging on NO 2 inequality estimates, finding that although their influence led to underestimations in absolute census tract-level differences, TROPOMI still captured key variations in NO 2 spatial distribution between tracts.…”