Wind observation around the tops of the midlatitude cirrus by the MU radar and Raman/Mie lidar

Abstract

Using a 46.5-MHz atmospheric radar referred to as the MU radar (MUR) and a Raman/Mie lidar installed at the Shigaraki (34• 51 N, 136• 06 E), continuous wind motions around the tops of the midlatitude cirrus are described for the first time. The cloud system extended from the northeast to southwest (35• N-50• N) along the eastward-moving trough and passed over Shigaraki in the nighttime between 5-6 November 2004. Cloud-top altitude observed by the lidar was located at ∼10.6 km around 1900 LST 5 November, then gradually descended to ∼8.4 km around 0500 LST 6 November. The westerly wind observed by MUR with 12-min and 150-m resolutions showed a rapid increase with altitude around the cloud tops and was almost always larger than 25 m s −1 above ∼1 km higher than the cloud tops. Objective reanalysis showed that a subtropical jet whose core existed to the south of Shigaraki caused a synoptic-scale vertical increase in the westerly wind around the cloud tops. Radiosondes observed a significant vertical increase of potential temperature (greater than 4 K within several hundred meters) around the cloud tops. MUR successfully observed fine time and altitude variations of winds which showed a good correspondence with the descending cloud tops.

Observations of Kelvin‐Helmholtz instability at a cloud base with the middle and upper atmosphere (MU) and weather radars

“…It is mainly sensitive to the clear air refractive index irregularities at the Bragg (i.e., half the radar wavelength) scale and is not affected by Rayleigh scattering from hydrometeors except during strong rain (typically when rainfall rate exceeds 10 mm h −1 ). Thus, direct measurements of vertical wind velocity (hereafter noted V air ) and horizontal wind velocity can be performed in cloud regions [e.g., Yamamoto et al , 2009a, 2009b].…”

Error estimation of spectral parameters for high-resolution wind and turbulence measurements by wind profiler radars

“…Wind profiler radars (WPRs), which detect refractive index irregularities at the Bragg scale (e.g., half the radar wavelength), are a useful means to measure vertical and horizontal wind velocity both in clear air and cloudy regions [e.g., Fukao, 2007;Hocking, 2011;Yamamoto et al, 2008Yamamoto et al, , 2009aYamamoto et al, , 2009b. Because the refractive index irregularities can be produced by temperature and humidity perturbations caused by atmospheric turbulence, WPRs can be used to measure turbulence parameters (e.g., dissipation rate and diffusivity) [e.g., Wilson, 2004].…”

Wind Motions around the Tropical Cirrus Using Simultaneous Radar and Lidar Observations over Gadanki (13.45°N, 79.18°E), India

“…Cirrus clouds form at different altitudes in different geographical locations, ranging from 8 to 20 km [5]. For example, at mid-latitudes, thin cirrus will occur between 8.5 and 11.5 km altitude region [6]- [10] with a persistence of few hours only which is because of rapid crystal growth and dissipation by precipitation due to high tropopause temperatures [11] and over tropics they usually occur in the altitude region of 8 -17 km [12]. In tropics the maximum occurrence of cirrus clouds is in the 13 -14 km altitude region [12].…”