DOI: 10.5061/dryad.vt4b8gv06
title: Data from: Physical mechanisms of deep convective boundary layer leading to dust emission in the Taklimakan desert

description: Deserts play an important role in the climate system, which is closely
 associated with the emission and transport of dust aerosols. Based on the
 intensive observation experiment in the Taklimakan Desert, the potential
 physical processes between the deep convective boundary layer (CBL) and
 dust emission are revealed in this study. Deep CBL enables the formation
 of clouds in the late afternoon, leading to significant cooling of
 surface. Large-scale buoyant coherent structures thereby transform into
 the mechanical coherent structures confined near the surface. The
 responses promote the earlier occurrence of low-level jet (LLJ) than in
 cloudless conditions, which allows the downward transport of LLJ momentum
 and substantially increases surface wind. Therefore, dust emission is
 initiated by strong wind at dusk and lasts for several hours. The results
 are useful to predict dust emissions and improve our understanding of
 distinctive boundary-layer processes in desert regions.
description: The intensive atmospheric boundary layer experiment was conducted
 from 1 to 31 May 2022 at Tazhong meteorological station (39° 00’ N, 83°
 40’ E), situated in the hinterland of the Taklimakan Desert. The station
 is surrounded by shifting sand and dunes. The intensive observations
 include an 80-m tower, a ceilometer, and the Global Positioning System
 (GPS) radiosonde. Mean temperature, humidity, and wind were measured at 10
 levels (0.5, 1, 2, 4, 10, 20, 32, 47, 63, and 80 m) on the tower. Sonic
 anemometer (CSAT-3, Campbell Scientific, Inc., USA) turbulence
 measurement, i.e., 20-Hz wind components and temperature, was obtained at
 10 m on the tower. Radiation components were measured using radiometers
 (Hukseflux, Netherlands) above the surface. The ceilometer (CHM 15k,
 Lufft, Inc., Germany) receives backscatter signals of clouds and aerosols
 from the zenith direction, with a spatiotemporal resolution of 15 m × 15
 s. Its laser wavelength is 1064 nm. GPS radiosondes were launched at
 05:15, 11:15, 17:15, and 23:15 LST (UTC+6 hr) during the observation
 period, to obtain the profile of temperature, humidity, pressure, wind
 speed, and wind direction. This study focuses on the cases that the deep
 CBL is followed by dust emissions at dusk, so three days (i.e., 16 May, 27
 May, and 28 May) were selected for the following analysis.
 The raw data observed from the sonic anemometer were processed
 over 30-min intervals using EddyPro v7.0.6 (LI-COR Inc., USA) software, to
 obtain fluctuations and turbulent statistics. The depth of CBL was
 determined based on GPS radiosondes and ceilometer observations,
 respectively. For the former, the top of CBL is identified as the peak
 height of potential temperature gradient, which is more accurate but only
 available at 11:15, 17:15 LST. For the latter, the top of CBL is defined
 as the height where the normalized range corrected signals rapidly
 decrease, accompanied by increased noise. This approach is available
 throughout the fair-weather daytime.
description: # Physical Mechanisms of Deep Convective Boundary Layer Leading to Dust
 Emission in the Taklimakan Desert
 The intensive atmospheric
 boundary layer experiment was conducted from 1 to 31 May 2022 at Tazhong
 meteorological station (39° 00’ N, 83° 40’ E), situated in the hinterland
 of the Taklimakan Desert. The station is surrounded by shifting sand and
 dunes. The intensive observations include an 80-m tower, a ceilometer, and
 the Global Positioning System (GPS) radiosonde. Mean temperature,
 humidity, and wind were measured at 10 levels (0.5, 1, 2, 4, 10, 20, 32,
 47, 63, and 80 m) on the tower. Sonic anemometer (CSAT-3, Campbell
 Scientific, Inc., USA) turbulence measurement, i.e., 20-Hz wind components
 and temperature, was obtained at 10 m on the tower. Radiation components
 were measured using radiometers (Hukseflux, Netherlands) above the
 surface. The ceilometer (CHM 15k, Lufft, Inc., Germany) receives
 backscatter signals of clouds and aerosols from the zenith direction, with
 a spatiotemporal resolution of 15 m × 15 s. Its laser wavelength is 1064
 nm. GPS radiosondes were launched at 05:15, 11:15, 17:15, and 23:15 LST
 (UTC+6 hr) during the observation period, to obtain the profile of
 temperature, humidity, pressure, wind speed, and wind direction. This
 study focuses on the cases that the deep CBL is followed by dust emissions
 at dusk, so three days (i.e., 16 May, 27 May, and 28 May) were selected
 for the following analysis. ## Description of the data and file structure
 1\. RCS_ceilometer.mat includes the normalized range-corrected signals
 measured by the ceilometer. For each case/day, the data were sampled every
 1 minute from 06:00 to 24:00 LST and every 15 m from the surface to 6,000
 m. Variables are named as beta_mmdd, where mm and dd represent month and
 day, respectively. 2\. Net_radiation.mat includes the net radiation
 measured from 06:00 to 24:00 LST with a resolution of 30 min for each
 case/day. Variables are named as Rn_mmdd, where mm and dd represent month
 and day, respectively. 3\. Meteorol_elements_10m.mat includes mean air
 pressure (pres_10m_mmdd, hPa), temperature (ta_10m_mmdd, K), and specific
 humidity (qv_10m_mmdd, kg/kg) measured at 10 m with a resolution of 30
 min, where mm and dd represent month and day, respectively. 4\.
 Fluctuations.mat includes the fluctuations of streamwise wind component
 (u_fluct_HHMM_mmdd), vertical velocity component (w_fluct_HHMM_mmdd), and
 potential temperature (t_fluct_HHMM_mmdd) measured at 10 m with a sample
 frequency of 20 Hz, where HH, MM, mm, and dd represent hour, minute,
 month, and day, respectively. 5\. Radiosonde.mat includes the profile of
 potential temperature (theta_HHMM_mmdd) and wind speed (ws_HHMM_mmdd)
 measured by GPS radiosonde, where HH, MM, mm, and dd represent hour,
 minute, month, and day, respectively. The vertical resolution is 10 m (see
 the variable named height). 6\. Tower_profile.mat includes the profile of
 temperature (ts_tower_HHMM) and wind speed (ws_tower_HHMM) measured on the
 80-m tower (see the variable named levels), where HH and MM represent hour
 and minute, respectively. 7\. Hodograph.mat includes the east-west and
 north-south wind components, u_80m_mmdd and v_80m_mmdd, respectively,
 measured at 80 m with a resolution of 30 min, where mm and dd represent
 month and day, respectively.