Showing papers by "Kristopher M. Bedka published in 2022"

Exploring the inorganic composition of the Asian Tropopause Aerosol Layer using medium-duration balloon flights

Abstract: . Satellite observations have revealed an enhanced aerosol layer near the tropopause over Asia during the summer monsoon, called the “Asian Tropopause Aerosol Layer” (ATAL). In this work, aerosol particles in the ATAL were collected with a balloon-borne impactor near the tropopause region over India, using extended-duration balloon flights, in summer 2017 and winter 2018. The chemical composition of these particles was further investigated by quantitative analysis using offline ion chromatography. Nitrate (NO − 3 ) and nitrite (NO − 2 ) were found to be the dominant ions in the collected aerosols with values ranging between 87 and 343 ng m − 3 at STP (standard temperature and pressure) during the summer campaign. In contrast, sulfate (SO 2 − 4 ) levels were found to be above the detection limit ( > 10 ng m − 3 at STP) only in winter. In addition, we determined the origin of the air masses sampled during the flights using the analysis of back trajectories as well as a convective proxy from cloud-top temperature fields derived from a geostationary satellite. The results obtained from this analysis were put into the context of large-scale transport and aerosol distribution using GEOS-Chem chemical transport model simulations. The first flight in summer 2017 which sampled an air mass within the Asian monsoon anticyclone (AMA), influenced by convection over Western China, was associated with particle size diameters from 0.05 to 0.15 µm. In contrast, the second flight sampled air masses at the edge of the AMA associated with a larger particle size radius ( > 2 µm) with a higher NO − 2 concentration. The sampled air masses in winter 2018 were likely affected by smoke from the Pacific Northwest fire event in Canada, which occurred 7 months before our campaign, associated with concentration enhancements of SO 2 − 4 and Ca 2 + . Overall, our results suggest that nitrogen-containing particles represent a large fraction of cloud-free and in-cloud aerosols populating the ATAL, which is partially in agreement with the results from aircraft measurements during the StratoClim (Stratospheric and upper tropospheric processes for better climate predictions) campaign. The exact nature of those particles is still unknown, but their coincidences with subvisible cirrus clouds and their sizes suggest nitric acid trihydrate (NAT) as a possible candidate, as NAT has already been observed in the tropical upper troposphere and lower stratosphere in other studies. Furthermore, GEOS-Chem model simulations indicate that lightning NO x emissions could have significantly impacted the production of nitrate aerosols sampled during the summer of 2017.

Coherent Lidar for Airborne Wind Measurements with High-Percentage Tropospheric Coverage

Abstract: A 2-micron coherent lidar has been developed with performance suitable for near continuous measurement of wind profiles from high-altitude aircraft to the Earth's surface under most atmospheric backscatter conditions.

Balloon-borne observations of acoustic-gravity waves from the 2022 Hunga Tonga eruption in the stratosphere

Abstract: The 15 January 2022 explosion of the Hunga Tonga-Hunga Ha’apai (HT-HH) volcano generated an extreme, quasi-instantaneous perturbation of the atmosphere. As part of its adjustment following the eruption, a rich spectrum of waves radiated away from HT-HH and achieved worldwide propagation. Among numerous platforms monitoring the event, two long-duration stratospheric balloons flying over the tropical Pacific provided unique observations of Lamb and infrasonic wave arrivals, detecting three revolutions of the Lamb wave and five of infrasound waves. Combined with ground measurements from the infrasound network of the International Monitoring System, such observations bring precious insights into the eruption process (chronology and altitude of energy release), and highlight previously unobserved long-range propagation of infrasound modes triggered by the eruption and their dispersion patterns. A comparison between ground- and balloon-based measurements emphasizes generally larger signal-to-noise ratios onboard the balloons and further demonstrates their potential for infrasound studies.

Satellite-Based Characterization of Convection and Impacts from the Catastrophic 10 August 2020 Midwest U.S. Derecho

Abstract: The catastrophic derecho that occurred on 10 August 2020 across the Midwest United States caused billions of dollars of damage to both urban and rural infrastructure as well as agricultural crops, most notably across the state of Iowa. This paper documents the complex evolution of the derecho through the use of low-Earth orbit passive-microwave imager and GOES-16 satellite-derived products complemented by products derived from NEXRAD weather radar observations. Additional satellite sensors including optical imagers and synthetic aperture radar (SAR) were used to observe impacts to the power grid and agriculture in Iowa. SAR improved the identification and quantification of damaged corn and soybeans, as compared to true-color composites and Normalized Difference Vegetation Index (NDVI). A statistical approach to identify damaged corn and soybean crops from SAR was created with estimates of 1.97 million acres of damaged corn and 1.40 million acres of damaged soybeans in the state of Iowa. The damage estimates generated by this study were comparable to estimates produced by others after the derecho, including two commercial agricultural companies.