Atmospheric Measurements Techniques Discussions

XCO2 estimates from the OCO-2 measurements using a neural network approach
Leslie David, Francois-Marie Bréon, and Frédéric Chevallier
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-177,2020
Preprint under review for AMT (discussion: open, 0 comments)
This paper shows that a Neural Network approach can be used to process spaceborne observations from the OCO-2 satellite and retrieve both the surface pressure and the atmospheric CO

Assessment of global total column water vapor sounding using a spaceborne differential absorption radar
Luis Millán, Richard Roy, and Matthew Lebsock
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-97,2020
Preprint under review for AMT (discussion: open, 0 comments)
This paper describes the feasibility of using a differential absorption radar technique for the remote sensing of total column water vapor from a spaceborne platform.

Development of a new correction algorithm applicable to any filter-based absorption photometer
Hanyang Li, Gavin R. McMeeking, and Andrew A. May
Atmos. Meas. Tech., 13, 2865–2886, https://doi.org/10.5194/amt-13-2865-2020, 2020
We present a new correction algorithm that addresses biases in measurements of aerosol light absorption by filter-based photometers, incorporating the transmission of light through the filter and some aerosol optical properties. It was developed using biomass burning aerosols and tested using rural ambient aerosols. This new algorithm is applicable to any filter-based photometer, resulting in good agreement between different colocated instruments in both the laboratory and the field.

Methodology for deriving the telescope focus function and its uncertainty for a heterodyne pulsed Doppler lidar
Pyry Pentikäinen, Ewan James O'Connor, Antti Juhani Manninen, and Pablo Ortiz-Amezcua
Atmos. Meas. Tech., 13, 2849–2863, https://doi.org/10.5194/amt-13-2849-2020, 2020
We provide a methodology for obtaining a function describing how the Doppler lidar telescope configuration impacts the measurements. Together with the function itself, we also provide the uncertainties in the function, which propagate through to provide uncertainties in the geophysical quantities obtained from the measurements. The method can be used to determine how stable the instrument is over time and also identify if changes have been made in the instrument setup.

The CopterSonde: an insight into the development of a smart unmanned aircraft system for atmospheric boundary layer research
Antonio R. Segales, Brian R. Greene, Tyler M. Bell, William Doyle, Joshua J. Martin, Elizabeth A. Pillar-Little, and Phillip B. Chilson
Atmos. Meas. Tech., 13, 2833–2848, https://doi.org/10.5194/amt-13-2833-2020, 2020
The CopterSonde is an unmanned aircraft system designed with the purpose of sampling thermodynamic and kinematic parameters of the lower Earth's atmosphere, with a focus on vertical profiles in the planetary boundary layer. By incorporating adaptive sampling techniques and optimizing the sensor placement, our study shows that CopterSonde can provide similar information as a radiosonde, but with more control of its sampling location at much higher temporal and spatial resolution.

Understanding cryogenic frost point hygrometer measurements after contamination by mixed-phase clouds
Teresa Jorge, Simone Brunamonti, Yann Poltera, Frank G. Wienhold, Bei P. Luo, Peter Oelsner, Sreeharsha Hanumanthu, Bhupendra B. Sing, Susanne Körner, Ruud Dirksen, Manish Naja, Suvarna Fadnavis, and Thomas Peter
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-176,2020
Preprint under review for AMT (discussion: open, 0 comments)
Balloon-borne frost point hygrometers are crucial for the monitoring of water vapour in the upper troposphere and lower stratosphere. We found that when traversing a mixed-phase cloud with big supercooled droplets, the intake tube of the instrument collects on its inner surface a high percentage of these droplets. The newly formed ice layer will sublimate at higher levels and contaminate the measurement. The balloon and instrument package are also investigated as source of the contamination.

Total column water vapour retrieval from S-5P/TROPOMI in the visible blue spectral range
Christian Borger, Steffen Beirle, Steffen Dörner, Holger Sihler, and Thomas Wagner
Atmos. Meas. Tech., 13, 2751–2783, https://doi.org/10.5194/amt-13-2751-2020, 2020
We present a total column water vapour (TCWV) retrieval analysing measurements from S-5P/TROPOMI in the visible blue spectral range. The retrieval can well capture the global water vapour distribution with similar sensitivity over the land and ocean and agrees well with various reference data sets within the estimated TCWV uncertainties of typically around 10 %–20 %.

A pyroelectric thermal sensor for automated ice nucleation detection
Fred Cook, Rachel Lord, Gary Sitbon, Adam Stephens, Alison Rust, and Walther Schwarzacher
Atmos. Meas. Tech., 13, 2785–2795, https://doi.org/10.5194/amt-13-2785-2020, 2020
We present a cheap, adaptable, and easily assembled thermal sensor for detecting microlitre droplets of water freezing. The sensor was developed to increase the level of automation in droplet array ice nucleation experiments, reducing the total amount of time required for each experiment. As a proof of concept, we compare the ice-nucleating efficiency of a crystalline and glassy sample of K-feldpsar. The glassy sample was found to be a less efficient ice nucleator at higher temperatures.

A powerful lidar system capable of one-hour measurements of water vapour in the troposphere and the lower stratosphere as well as the temperature in the upper stratosphere and mesosphere
Lisa Klanner, Katharina Höveler, Dina Khordakova, Matthias Perfahl, Christian Rolf, Thomas Trickl, and Hannes Vogelmann
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-90,2020
Preprint under review for AMT (discussion: open, 0 comments)
The importance of water vapour as the most influential greenhouse gas and for the air composition calls for detailed investigations. The details of the highly inhomogeneous distribution of water vapour can be determined with lidar, the very low concentrations at high altitudes imposing a major challenge. An existing water-vapour lidar in the Bavarian Alps was recently complemented by a powerful Raman lidar that provides water vapour up to 20 km and temperature up to 90 km with just one hour.

Model-based climatology of diurnal variability in stratospheric ozone as a data analysis tool
Stacey M. Frith, Pawan K. Bhartia, Luke D. Oman, Natalya A. Kramarova, Richard D. McPeters, and Gordon J. Labow
Atmos. Meas. Tech., 13, 2733–2749, https://doi.org/10.5194/amt-13-2733-2020, 2020
We use the NASA GEOS-GMI chemistry climate model to construct a climatology of stratospheric ozone diurnal variations as a function of latitude, pressure and month, which can be used in a variety of data analysis tasks involving ozone observations made at different times of the day. The climatology compares well with previous modeling simulations and available observations, and to the authors' knowledge is the first characterization of the diurnal cycle available for general ozone data analyses.

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