Analysis of the characteristics of gravity waves during a local rainstorm event in Foshan,China

A detailed analysis of the dynamic frequency spectrum characteristics of gravity waves(GWs)during a local heavy rainfall event on 20–21 November 2016 in Foshan,China,is presented.The results of this analysis,which was based on high-precision microbarograph data,indicate that GWs played a key role in generating the rainstorm.The GWs experienced two intermittent periods of amplitude enhancement and period widening.The largest amplitudes of the GWs were 80–160 Pa,with a corresponding period range of 140–270 min,which were approximately 4 h ahead of the rainstorm.The severe storms appeared to affect the GWs by augmenting the wave amplitudes with center amplitudes of approximately 80–100 Pa and periods ranging between 210 and 270 min;in particular,the amplitudes increased to approximately 10 Pa for GWs with shorter periods(less than 36 min).The pre-existing large-amplitude GWs may be precursors to severe storms;that is,these GWs occurred approximately 4 h earlier than the time radars and satellites identified convections.Thus,these results indicate that large-amplitude GWs constitute a possible mechanism for severe-storm warning.

Activity of cold vortex in northeastern China and its connection with the characteristics of precipitation and circulation during 1960-2012

Based on the daily reanalysis data released by NCEP/NCAR and the daily precipi- tation of 753 Chinese stations from May to August during the period of 1960 to 2012, the statistical characteristics of the cold vortex in northeastern China were analyzed. In addition, the strength index, which described the characteristics of the vortex consistently and fre- quently, and the geographical distribution were given by continuous anomalies of circulation. Based on this index, the activity routines of the cold vortex, characteristics of atmospheric circulation, and their effects on precipitation in northeastern China were analyzed. The results show that： the activities of the cold vortex exhibit remarkable features of annual and interde- cadal oscillation, and the vortex high frequency and its characteristics of atmospheric circula- tion are described more accurately by the strength index of the cold vortex, which shows a high correspondence with the vortex precipitation during early summer and midsummer in the northeast. In strong （weak） vortex years, the general circulation in the middle and high lati- tudes of Eurasia is to the advantage （disadvantage） of the formation, development and maintenance of the cold vortex, thus it is easy （difficult） to form the circulation which is bene- ficial to transmit vapor from south to north during the period of July to August. Blocking over the Ural Mountains prevails （does not prevail） in early summer, and blocking over the Sea of Okhotsk prevails （does not prevail） in midsummer. Areas where the subtropical high is too small （large） and moves toward the north too late （early） are better （worse） for the mainte- nance of the cold vortex in northeastern China.

STATISTICAL CORRELATIONS BETWEEN SNOW COVER OF EURASIA IN WINTER-SPRING AND RAINFALL AND TEMPERATURE OF EAST-ERN CHINA IN SUMMER

Recently, the anomaly of ice-snow cover and climate in the whole world were ardently discussed. Thirty years ago, Lu Jiong analysed the correlation between the amount of sea-ice in the Okhotsk Sea and the plum rains in the middle and lower reach-

POSSIBILITY TO USE SCH(?)RDINGER EQUATION TO DESCRIBE LARGE-SCALE PROBABILITY WAVES AND ITS APPLICATION IN SEASONAL PREDICTION

Under the influence of a one-dimensional stationary outfield with the equilibrium between kinetic and potential energy produced by it,a modified Sch(?)rdinger equation in the form i((?)ψ/(?)t)t=a (?)~2ψ/ax^2-ib (?),where b=b_o(?)T/(?)x,is used to describe the behavior of the probability wave on the six-month departure charts at the 500 hPa level.It is found that C=2πa/L-b_o(?)T/ax and when L→∞,then C= -b_o(?)T/(?)x,where C is wave velocity,a and b are constants,and L is wavelength.The motion direction of probability waves is against the outfield temperature gradient,and their velocity is related to the absolute value of temperature gradient.The motion of waves shrinks in heat sinks and expands in heat sources,which have been verified in practice.Finally the six-month departure probability wave and the modified Sch(?)rdinger equation are used in the MOS predictions of temperature and rainfall in spring-summer 1981-1985 in Jilin Province and the accuracy for trend predictions is equal to 80%.