By using the radiosonde measurements collected at Shouxian,China,we examined the dynamics and thermodynamics of single- and two-layer clouds formed at low and middle levels.The analyses indicated that the horizontal wind speed above the cloud layers was higher than those within and below cloud layers.The maximum balloon ascent speed(5.3 m s^(-1)) was located in the vicinity of the layer with the maximum cloud occurrence frequency(24.4%),indicating an upward motion(0.1-0.16 ms^(-1)).The average thickness,magnitude and gradient of the temperature inversion layer above single-layer clouds were117±94 m,1.3±1.3℃ and 1.4±1.5℃(100 m)^(-1),respectively.The average temperature inversion magnitude was the same(1.3℃) for single-low and single-middle clouds;however,a larger gradient[1.7±1.8℃(100 m)^(-1)]and smaller thickness(94±67 m) were detected above single-low clouds relative to those above single-middle clouds[0.9±0.7℃(100 m)^(-1) and157±120 m].For the two-layer cloud,the temperature inversion parameters were 106±59 m,1.0±0.9℃ and 1.0±1.0℃(100 m)^(-1) above the upper-layer cloud and 82 ± 60 m,0.6±0.9℃ and 0.7±0.6℃(100 m)^(-1) above the low-layer cloud.Absolute differences between the cloud-base height(cloud-top height) and the lifting condensation level(equilibrium level)were less than 0.5 km for 66.4%(36.8%) of the cases analyzed in summer.
Jinqiang ZHANGHongbin CHENXiang'ao XIAWei-Chyung WANG
This paper presents a high performance electric field micro sensor with combined differential structure.The sensor consists of two backward laid micro-machined chips,each packaged by polymer and metal.The novel combined differential structure effectively reduces various environmental affections,such as thermal drift,humidity drift and electrostatic charge accumulation.The sensor is tested in near-ground place as well as balloon-borne sounding.In different weather conditions,the measurement results showed good agreement with those of the commercial electric field mill.
Using the data collected over the Southern Great Plains ARM site from 2006 to 2010, the surface Active Remote Sensing of Cloud(ARSCL) and Cloud Sat-CALIPSO satellite(CC) retrievals of total cloud and six specified cloud types [low, mid–low(ML), high–mid–low(HML), mid, high–mid(HM) and high] were compared in terms of cloud fraction(CF), cloud-base height(CBH), cloud-top height(CTH) and cloud thickness(CT), on different temporal scales, to identify their respective advantages and limitations. Good agreement between the two methods was exhibited in the total CF. However, large discrepancies were found between the cloud distributions of the two methods at a high(240-m) vertical grid spacing. Compared to the satellites, ARSCL retrievals detected more boundary layer clouds, while they underestimated high clouds. In terms of the six specific cloud types, more low- and mid-level clouds but less HML- and high-level clouds were detected by ARSCL than by CC. In contrast, the ARSCL retrievals of ML- and HM-level clouds agreed more closely with the estimations from the CC product. Lower CBHs tended to be reported by the surface data for low-, ML- and HML-level clouds; however, higher CTHs were often recorded by the satellite product for HML-, HM- and high-level clouds. The mean CTs for low- and ML-level cloud were similar between the two products; however, the mean CTs for HML-, mid-, HM- and high-level clouds from ARSCL were smaller than those from CC.
In this paper,the design and experimental results for a novel high-stability sounding electrostatic field micro sensor are presented.By means of hermetic chip sealing,digital weak signal demodulation unit,and probe sensor structure design,harsh environmental adaptation problems such as low temperature,high humidity,low air pressure,waterfall are solved.The sensor has a high resolution of 14 V/m,a wide measurement range of±100 kV/m,and is proved to have superior stability and performance in sounding electric field experiments than traditional sensors under different kinds of weather.
