Simulation study for measurement of horizontal wind profiles in the polar stratosphere and mesosphere using ground-based observations of ozone and carbon monoxide lines in the 230–250 GHz region

Abstract

Abstract. Meteorological and atmospheric models are being extended up to 80 km altitude but there are very few observing techniques that can measure stratospheric-mesospheric winds at altitudes between 20 and 80 km to verify model datasets. Here we demonstrate the feasibility of horizontal wind profile measurements using ground-based passive millimetre-wave spectroradiometric observations of ozone lines centred at 231.28, 249.79, and 249.96 GHz. Vertical profiles of horizontal winds are retrieved from forward and inverse modelling simulations of the line-of-sight Dopplershifted atmospheric emission lines above Halley station (75 • 37 S, 26 • 14 W), Antarctica. For a radiometer with a system temperature of 1400 K and 30 kHz spectral resolution observing the ozone 231.28 GHz line we estimate that 12 h zonal and meridional wind profiles could be determined over the altitude range 25-74 km in winter, and 28-66 km in summer. Height-dependent measurement uncertainties are in the range 3-8 m s −1 and vertical resolution ∼ 8-16 km. Under optimum observing conditions at Halley a temporal resolution of 1.5 h for measuring either zonal or meridional winds is possible, reducing to 0.5 h for a radiometer with a 700 K system temperature. Combining observations of the 231.28 GHz ozone line and the 230.54 GHz carbon monoxide line gives additional altitude coverage at 85 ± 12 km. The effects of clear-sky seasonal mean winter/summer conditions, zenith angle of the received atmospheric emission, and spectrometer frequency resolution on the altitude coverage, measurement uncertainty, and height and time resolution of the retrieved wind profiles have been determined.

Vertical wind profiling from the troposphere to the lower mesosphere based on high-resolution heterodyne near-infrared spectroradiometry

“…According to the antenna theorem (Siegman, 1966), the single-mode fiber geometric aperture factor is ∼ 2.6 × 10 −8 cm 2 , which corresponds to field of view ∼ 0.006 • . This is close to the maximum available for heterodyne detection and therefore does not limit the instrument sensitivity (Rodin et al, 2014). An automated Sky-Watcher EQ6 PRO SynScan equatorial mount equipped with a QHY5-II guide camera was used to track the Sun during observations.…”

“…The basic principles of the diode laser heterodyne spectroradiometry (TDLHS) have been presented in detail in previous works, e.g., in Rodin et al (2014), O'Byrne (2016), andZenevich et al (2019). Here we briefly repeat the core information important for Doppler measurements.…”

“…Commercial DFB lasers are supplied with embedded Peltier coolers and thermal sensors, so both parameters could be precisely controlled by external electronics. We apply the algorithm of LO sweeping with locking to reference the absorption line, as described in Rodin et al (2014). According to this algorithm, the temperature controller is set at a constant value, while the pumping current is modulated by a piecewise linear saw-edged function.…”

“…Several examples of near-infrared heterodyne spectroradiometers utilizing the Sun as a radiation source have been recently developed for the purpose of greenhouse gas measurements, including methane and carbon dioxide (Rodin et al, 2014;Wilson et al, 2014;Melroy et al, 2015;Kurtz and O'Byrne, 2016;Hoffmann et al, 2016;Zenevich et al, 2019;Deng et al, 2019;Wang et al, 2019). Weidmann et al (2017) took advantage of the compact design of a fiber-based heterodyne spectroradiometer and proposed a CubeSat-class mission for methane isotopologue measurements.…”

Vertical wind profiling from troposphere to the lower mesosphere based on high resolution heterodyne near-infrared spectroradiometry

“…In contrast with radar and lidar sounding, passive Doppler spectroradiometry has received much less attention in atmospheric studies. Recent developments in the microwave Doppler wind velocimetry have been reported by Newnham et al (2016). The authors argue that in the stratosphere and lower mesosphere, passive high resolution spectroradiometry in the microwave remain one of the most effective technique of direct wind monitoring.…”