Abstract:1. A brief resume of the past 25 years of the N.I.M.. 2. Main experiences in running the Institute. 3. Plan of development, essential ideas of educational reform, andconcrete steps of reform to be taken in the next couple of years.

Abstract:The role of eddies in the seasonal changes of general circula-tion over the Northern Hemisphere is studied by means of Eliassen-Palm theory. It is found that eddy transfer of baroclinic energyfrom the lower troposphere over the mid-latitudes to the subtropical tropopause region is closely related to the seasonal varia-tions of position and instensity of the subtropical jet stream. The response of zonal mean flow to the force of eddies is evident inearly summer with a sudden shift of the jet stream but only barely discernible during the shift in late autumn. Calculations showthat the enforced action of the eddies is favorable in maintaining acceleration of the westerlies to the north of the jet stream. The contributions of eddy transfer, diabatic heating and vertical diffusion are evaluated respectively by using a two-dimensional diagnostic model. Changes in the heating field are found to playan important part in the seasonal variations of the general circulation pattern whether in early summer or late autumn where a seffects of vertical diffusion of turbulent motions is more pronounced in late autumn.

Abstract:Moisture transfer around the low level jet (LLJ) and its effecton rainstorms are studied. based on thc data of the Heavy Rainfall Experiment over South China during the "early flood"seasons of 1977 to 1979. It is found that development of rainstorms associated with the LLJ is caused mainly by lateral convergence of moisture under the LLJ axis rather than at the same level with the axis. The flow of moisture under the LLJ moves from right to left, as-cends in the storm area, turns right at higher levels above theaxis and then subsides. Thus a meso-scale cell of moisture trans-portation is formed, which is superimposed on the large scalecirculation around the LLJ, a feature favorable for the main-tenance of rainstorms. Winds in the boundary layer under the LLJ veer with altitudedue to friction. This accounts for the lateral transfer of moisture.Hence rainstorms may develop anywhere on the left of the LLJ.

Abstract:Using a two-layer model, Pedlosky had studied baroclinic insta-bility of zonal flow on a frictionless β-plane and on a f-plane withfriction respectively. On the basis of his findings, baroclinic insta-bility on a β-plane with friction and with heating from convectivecondensation is investigated, yielding linear results. A nonlineartheory will be discussed in a separate paper. The curves of critica1 shear (U_c^*)-wave number (A^*2) are used toanalyze the linear baroclinic instability influenced by β-effect, frictionand heating from convection. It is shown that not on1y the β-effectalone could contribute to increasing stability but its combination withfriction and heating from convection can also make the curves ofcritical stability asymmetrical. This implies that the positive andnegative shears of equal absolute values may differ in stability. Fric-tion (r) may serve as a stabilizing factor, but the β-effect with aweak friction is less stable than that without friction. Heating fromconvection (m^*) always increases the baroclinic instability and makesfriction a destabilizing factor when m^*> 1. Under the condition ofm^*< 1 and that dissipation exists in layers both above and below,the long-wave cutoff for A^*2= L^*2 appears in this model. And wavenumber of the short-wave cutoff increases infinitely as intensificationof heat (m^*→1) continues. In addition, medium-wave cutoffs also existin the critical curves.

Abstract:A formula is presented for the vertical decrease of water vaporpressure based on data from 103 radiosonde stations throughout thecountry. Annual mean value and monthly means for January, April,July and October of coefficients of vertical decrease in vapor pressureare calculated for the free atmosphere and along the mountain slopes.Factors affecting these coefficients are discussed. Classification and delineation of annual variations are made. On this basis a chartshowing the distributions of the decrease coefficients in both casesover the country is constructed. Finally analysis and comparison are made of the distribution patterns.

Abstract:According to field experiments in the past two years of a varietyof winter wheat with different sowing dates, the tempering for coldresistence before wintering, the interrupted growth of green leaves during winter and the main symptoms of frost damage are investigated.It is found that the recouping effects of tillering and earing for frost-injured stems may offset the decrease of yield. Based on climatological data, classification of safe and hazardous types, each of which contains 3 substypes is made of overw intering ecological conditions.

Abstract:A technique for processing real- time weather radar echoes withthe aid of micro processors is presented, which includes systematic descriptions of the interfaces, softwares, coordinate trans formation,color display, angle signal production and a principle of real-time processing of digital signals.