Quasi‐Lagrangian measurements of nitric acid trihydrate formation over Antarctica

Abstract

In 2010, the joint French-United States Concordiasi project released 19 long-duration superpressure balloons from McMurdo Station, Antarctica. Four of these balloons carried a gondola with particle counters and temperature sensors to measure polar stratospheric clouds. One gondola spent 5 days at stable temperatures between equilibrium temperatures for nitric acid trihydrate (NAT) and for supercooled ternary solution droplets. Sporadic particles with radii between 0.46 μm and 4.5 μm were measured in a small fraction of the measurements. At these times the corresponding size distributions and total particle volumes were consistent with NAT. Although the fraction of these observations was less than 3%, their frequency increased with time over the 5 days. From this frequency the NAT nucleation rate at 3°C below T NAT was estimated to be 2 × 10 À4 m À3 s À1 ± 60% for these late winter austral NAT observations at a potential temperature of 410-415 K. Interspersed with these measurements of polar stratospheric cloud particles consistent with NAT were many more measurements of particles consistent with background stratospheric aerosol indicating that the polar stratospheric clouds sampled were highly discontinuous.

Retrieval of Aerosol Size Distributions From In Situ Particle Counter Measurements: Instrument Counting Efficiency and Comparisons With Satellite Measurements

“…It can be applied to any OPC for which counting efficiency curves are available, thus to the OPC25 and the laser based OPC described by Ward et al (2014). The explicit CEF method provides the best option for deriving aerosol size distributions from the Wyoming balloon-borne in situ measurements using the OPC40 instrument.…”

“…It does not have to explicitly account for the calibration error associated with the OPC40. It can be applied to any OPC for which counting efficiency curves are available, thus to the OPC25 and the laser based OPC described by Ward et al (2014). It provides results that are substantially equivalent to the corrections suggested by KD15, thus displaying the capability to account for the calibration error of the OPC40.…”

“…Ward et al (2014) describe this instrument when it was used for polar stratospheric cloud measurements. This is the case for the laser particle counter, which began measurements in Laramie in 2008.…”

“…This is the case for the laser particle counter, which began measurements in Laramie in 2008. Ward et al (2014) describe this instrument when it was used for polar stratospheric cloud measurements. Some Laramie measurements from this latest instrument are presented in Kremser et al (2016) and are used for comparison in a paper on volume retrieval from infrared emission measurements (Günther et al, 2018), but this instrument will not be discussed further here.…”

First quasi-Lagrangian in situ measurements of Antarctic Polar springtime ozone: observed ozone loss rates from the Concordiasi long-duration balloon campaign

“…Ozone instruments were built by two groups -one at the Laboratoire de Météorologie Dynamique in Paris, France, hereafter referred to as LMDOz, and one at the University of Colorado Boulder, hereafter designated UCOz. Four of the six ozone balloons additionally carried laser particle counters from the University of Wyoming (Ward et al, 2014).…”