Abstract.The Whistler Aerosol and Cloud Study (WACS 2010), included intensive measurements of trace gases and particles at two sites on Whistler Mountain. Between 6-11 July 2010 there was a sustained high-pressure system over the region with cloud-free conditions and the highest temperatures of the study. During this period, the organic aerosol concentrations rose from <1 µg m −3 to ∼6 µg m −3 . Precursor gas and aerosol composition measurements show that these organics were almost entirely of secondary biogenic nature. Throughout 6-11 July, the anthropogenic influence was minimal with sulfate concentrations <0.2 µg m −3 and SO 2 mixing ratios ≈0.05-0.1 ppbv. Thus, this case provides excellent conditions to probe the role of biogenic secondary organic aerosol in aerosol microphysics. Although SO 2 mixing ratios were relatively low, box-model simulations show that nucleation and growth may be modeled accurately if J nuc = 3 × 10 −7 [H 2 SO 4 ] and the organics are treated as effectively non-volatile. Due to the low condensation sink and the fast condensation rate of organics, the nucleated particles grew rapidly (2-5 nm h −1 ) with a 10-25 % probability of growing to CCN sizes (100 nm) in the first two days as opposed to being scavenged by coagulation with larger particles. The nucleated particles were observed to grow to ∼200 nm after three days. Comparisons of sizedistribution with CCN data show that particle hygroscopicity (κ) was ∼0.1 for particles larger 150 nm, but for smaller particles near 100 nm the κ value decreased near midway through the period from 0.17 to less than 0.06. In this environment of little anthropogenic influence and low SO 2 , the rapid growth rates of the regionally nucleated particles -due to condensation of biogenic SOA -results in an unusually high efficiency of conversion of the nucleated particles to CCN. Consequently, despite the low SO 2 , nucleation/growth appear to be the dominant source of particle number.

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Lidar technology has been rapidly advancing over the past several decades. It can be used to measure a variety of atmospheric constituents at very high temporal and spatial resolutions. While the number of lidars continues to increase worldwide, there is generally a dependency on an operator, particularly for high-powered lidar systems. Environment and Climate Change Canada (ECCC) has recently developed a fully autonomous, mobile lidar system called AMOLITE (Autonomous Mobile Ozone Lidar Instrument for Tropospheric Experiments) to simultaneously measure the vertical profile of tropospheric ozone, aerosol and water vapor (nighttime only) from near the ground to altitudes reaching 10 to 15 km. This current system uses a dual-laser, dual-lidar design housed in a single climate-controlled trailer. Ozone profiles are measured by the differential absorption lidar (DIAL) technique using a single 1 m Raman cell filled with CO 2 . The DIAL wavelengths of 287 and 299 nm are generated as the second and third Stokes lines resulting from stimulated Raman scattering of the cell pumped using the fourth harmonic of a Nd:YAG laser (266 nm). The aerosol lidar transmits three wavelengths simultaneously (355, 532 and 1064 nm) employing a detector designed to measure the three backscatter channels, two nitrogen Raman channels (387 and 607 nm) and one cross-polarization channel at 355 nm. In addition, we added a water vapor channel arising from the Ramanshifted 355 nm output (407 nm) to provide nighttime water vapor profiles. AMOLITE participated in a validation experiment alongside four other ozone DIAL systems before being deployed to the ECCC Oski-ôtin ground site in the Alberta oil sands region in November 2016. Ozone was found to increase throughout the troposphere by as much as a factor of 2 from stratospheric intrusions. The dry stratospheric air within the intrusion was measured to be less than 0.2 g kg −1 . A biomass burning event that impacted the region over an 8day period produced lidar ratios of 35 to 65 sr at 355 nm and 40 to 100 sr at 532. Over the same period the Ångström exponent decreased from 1.56±0.2 to 1.35±0.2 in the 2-4 km smoke region.

Abstract. The North America-based Tropospheric Ozone Lidar Network (TOLNet) was recently established to provide high spatiotemporal vertical profiles of ozone, to better understand physical processes driving tropospheric ozone variability and to validate the tropospheric ozone measurements of upcoming spaceborne missions such as Tropospheric Emissions: Monitoring Pollution (TEMPO). The network currently comprises six tropospheric ozone lidars, four of which are mobile instruments deploying to the field a few times per year, based on campaign and science needs. In August 2016, all four mobile TOLNet lidars were brought to the fixed TOLNet site of JPL Table Mountain Facility for the 1-week-long Southern California Ozone Observation Project (SCOOP). This intercomparison campaign, which included 400 h of lidar measurements and 18 ozonesonde launches, allowed for the unprecedented simultaneous validation of five of the six TOLNet lidars. For measurements between 3 and 10 km a.s.l., a mean difference of 0.7 ppbv (1.7 %), with a root-mean-square deviation of 1.6 ppbv or 2.4 %, was found between the lidars and ozonesondes, which is well within the combined uncertainties of the two measurement techniques. The few minor differences identified were typically associated with the known limitations of the lidars at the profile altitude extremes (i.e., first 1 km above ground and at the instruments' highest retrievable altitude). As part of a large homogenization and quality control effort within the network, many aspects of the TOLNet in-house data processing algorithms were also standardized and validated. This thorough validation of both the measurements and retrievals builds confidence as to the high quality and reliability of the TOLNet ozone lidar profiles for many years to come, making TOLNet a valuable ground-based reference network for tropospheric ozone profiling.

Abstract. LIDAR technology has been rapidly advancing over the past several decades. It can be used to measure a variety of atmospheric constituents at very high temporal and spatial resolutions. While the number of LIDARs continues to increase worldwide, there is generally a dependency on an operator, particularly for high-powered LIDAR systems. Environment and Climate Change Canada (ECCC) has recently developed a fully autonomous, mobile LIDAR system called AMOLITE (Autonomous Mobile Ozone LIDAR Instrument for Tropospheric Experiments) to simultaneously measure the vertical profile of tropospheric ozone, aerosol and water vapor (night time only) from near ground to altitudes reaching ten to fifteen kilometers. This current system uses a dual laser, dual LIDAR design housed in a single climate-controlled trailer. Ozone profiles are measured by the DIfferential Absorption LIDAR (DIAL) technique using a single 1 m Raman cell filled with CO2. The DIAL wavelengths of 287 nm and 299 nm are generated as the second and third Stokes lines resulting from stimulated Raman scattering of the cell pumped using the fourth harmonic of a Nd:YAG laser (266 nm). The aerosol LIDAR transmits three wavelengths simultaneously (355 nm, 532 nm and 1064 nm) employing a detector designed to measure the three backscatter channels, two nitrogen Raman channels (387 nm and 607 nm), and one cross-polarization channel at 355 nm. In addition, we have added a water vapor channel arising from the Raman-shifted 355 nm output (407 nm) to provide nighttime water vapor profiles. AMOLITE participated in a validation experiment alongside four other ozone DIAL systems before being deployed to the ECCC Oski-ôtin ground site in the Alberta Oil Sands region in November 2016. Ozone was found to increase throughout the troposphere by as much as a factor of 2 from stratospheric intrusions. A biomass burning event that impacted the region over an eight-day period produced LIDAR ratios of 35 to 65 sr at 355 nm and 40 to 100 sr at 532. Over the same period the Angstrom exponent decreased from 1.56 ± 0.2 to 1.35 ± 0.2 between the 2 to 4 km smoke region. The advantage of nearly continuous measurements obtained over a 12-month period will be presented, highlighting the synergistic advantage of AMOLITE’s tri-LIDAR design.