Development of a cloud particle sensor for radiosonde sounding

Abstract

Abstract. A meteorological balloon-borne cloud sensor called the cloud particle sensor (CPS) has been developed. The CPS is equipped with a diode laser at ∼ 790 nm and two photodetectors, with a polarization plate in front of one of the detectors, to count the number of particles per second and to obtain the cloud-phase information (i.e. liquid, ice, or mixed). The lower detection limit for particle size was evaluated in laboratory experiments as ∼ 2 µm diameter for water droplets. For the current model the output voltage often saturates for water droplets with diameter equal to or greater than ∼ 80 µm. The upper limit of the directly measured particle number concentration is ∼ 2 cm −3 (2×10 3 L −1 ), which is determined by the volume of the detection area of the instrument. In a cloud layer with a number concentration higher than this value, particle signal overlap and multiple scattering of light occur within the detection area, resulting in a counting loss, though a partial correction may be possible using the particle signal width data. The CPS is currently interfaced with either a Meisei RS-06G radiosonde or a Meisei RS-11G radiosonde that measures vertical profiles of temperature, relative humidity, height, pressure, and horizontal winds. Twenty-five test flights have been made between 2012 and 2015 at midlatitude and tropical sites. In this paper, results from four flights are discussed in detail. A simultaneous flight of two CPSs with different instrumental configurations confirmed the robustness of the technique. At a midlatitude site, a profile containing, from low to high altitude, water clouds, mixed-phase clouds, and ice clouds was successfully obtained. In the tropics, vertically thick cloud layers in the middle to upper troposphere and vertically thin cirrus layers in the upper troposphere were successfully detected in two separate flights. The data quality is much better at night, dusk, and dawn than during the daytime because strong sunlight affects the measurements of scattered light.

Coordinated Upper-Troposphere-to-Stratosphere Balloon Experiment in Biak

“…4, top). Simultaneous with radiosonde observations of temperature, relative humidity, and GPS position, precise values of low-concentration water vapor, ozone, and cloud particles (Vömel et al 2007;Komhyr et al 1995;Fujiwara et al 2016) were measured at high vertical resolution. GPS altitude was converted to air Table 2.…”

“…The complementary continuous operation of remote sensing lidar and intermittent in situ observations by CPS sondes monitored ice nucleation processes in TTL dehydration. Fujiwara et al (2016) presented the profiles obtained from two of the four CPS flights. For the 27 February case, CPS data showed reasonable agreement with the lidar measurements.…”

“…The SOWER group has been conducting field observations across the tropical Pacific to study TTL and stratospheric processes since 1998 (Fujiwara et al 2001;Shiotani et al 2002;Takashima et al 2008). Ozonesondes and water vapor sondes have been launched together with conventional radiosondes.…”

“…Simultaneous observations of aerosols by a Mie lidar provide important information on ice nucleation in TTL clouds (Shibata et al 2007). In response to the proposal of the cold-trap hypothesis, SOWER focused on observations in the western tropical Pacific to investigate the efficiency of TTL dehydration (Fujiwara et al 2010;Shibata et al 2012;Hasebe et al 2013;Inai et al 2013) in collaboration with LAPAN.…”

Cloud vertical structure over a tropical station obtained using long-term high-resolution radiosonde measurements

“…For that we have launched cloud particle sensor (CPS) sonde (Fujiwara et al, 2016) at Gadanki, which provides a profile of cloud number concentration. Results from a flight of RS-11G radiosonde and cloud particle sensor (CPS) sonde on the same balloon launched at 02:00 LT on 4 August 2017 at Gadanki, India, are shown in Fig.…”