Based on the monthly maximum frozen soil depth at 68 meteorological stations in Shanxi Province during 1960-2018, the temporal and spatial distribution characteristics of the annual maximum frozen soil depth in Shanxi were studied by using EOF and wavelet analysis methods. The results are as follows: (1) The average annual maximum frozen soil depth at 68 stations in Shanxi during 1960-2018 was 71 cm, the extremely maximum value was 192 cm, and the extremely minimum value was 7 cm. In the past 59 years, the average annual maximum frozen soil depth at 68 stations in Shanxi showed a significantly decreasing trend with a climate tendency rate of -1.394 cm per decade, and it mutated in 1986. (2) The quasi-4-year period of average annual maximum frozen soil depth at 68 stations in Shanxi was detected. (3) The annual maximum frozen soil depth showed a spatial distribution characteristics with shallow in southern and deep in northern Shanxi, shallow in eastern and deep in western Shanxi. (4) The accumulated variance contribution rate of the first two modes of the annual maximum frozen soil depth in Shanxi reached 58.4%. The spatial pattern of the first mode was consistent in the whole province, while that of the second mode was reverse in southern and northern Shanxi.
A stratiform cloud wasmeasured with a ParticleMeasurement System ( PMS) p roduced byDrop letMeasurement Technologies (DMT) and mounted on a Y - 12 aircraft in sp ring of 2008, Beijing. It was found that the average concentration of cloud particles measured by CAS (Cloud and Aerosol Spectrometer) was bigger than those valuesmeasured by FSSP in other areas of north China. It was also found that the average concentrations of ice particlesmeasured by CIP (Cloud Imaging Probe) , 2D - C and 2D - GA2 were all similar. A positive correlation was found between snow and ice crystals’concentrations. A negative correlation was found between the concentration of ice crystal and the ratio of snow and ice crystal concentrationswhen the concentration of ice crystalswas less than 104 m- 3 , butwhen more than 104 m- 3 , the ratio of snow and ice crystal concentration is a constant. Many ice crystals were found in the cloud field where the temperature ranged from - 10 to - 12 ℃, and there wasmore supercooled water in the field. The p recip itation particleswere p ropagated in the cloud filed where the temperature ranged from - 7 to - 10 ℃. Precip itation particles evaporated and became smaller in the cloud filed where the temperature ranged from - 5 to - 7 ℃. L ittle p recip itation particleswas found in the cloud field where the temperature ranged from - 4 to - 5 ℃.