The instruments were deployed on the NSF C-130 aircraft during WE-CAN 2018 as well as the NASA DC-8 and the NOAA Twin Otter aircraft during FIREX-AQ 2019, where they sampled fresh and moderately aged wildfire plumes. Each instrument measured light absorption over a broad wavelength range using a liquid waveguide capillary cell (LWCC) and grating spectrometer, with particles collected into water by a particle-into-liquid sampler (CSU PILS-LWCC and NOAA PILS-LWCC) or a mist chamber (MC-LWCC). We describe the first direct, online measurements of water-soluble BrC on research aircraft by three separate instruments. The lack of direct measurements of BrC has limited our understanding of its prevalence, sources, evolution, and impacts. Some organic chromophores are especially toxic, linking BrC to adverse health effects. Ambient studies show that as a component of aerosol particles, BrC affects photochemical reaction rates and regional to global climate. Weber Received: вЂ“ Discussion started: вЂ“ Revised: вЂ“ Accepted: вЂ“ Published: Д«rown carbon (BrC) consists of particulate organic species that preferentially absorb light at visible and ultraviolet wavelengths. Weber Hide author detailsД¬orrespondence: Rodney J. 8 Department of Chemistry, University of Colorado Boulder, Boulder, CO, USAД¬orrespondence: Rodney J.6 Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, USA.

5 Atmospheric Chemistry Observations and Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, USA.

4 College of Engineering and Physical Sciences, University of New Hampshire, Durham, NH, USA.

3 Chemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA.

2 Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA.

1 School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA.

Started from the bottom sampled