Abstract:A new initialization scheme used for the five-level primitive equationmodel in the Northern Hemisphere (designated as Model B for sim-plicity) is given. The procedure is as follows. First, 5 verticalmodes of the corresponding linearized primitive equations in the so-called mixed coordinates are evaluated. Then a chosen objective ana-lyzed wind field and a geopotential field are expanded in terms ofthese modes. Finally, by using the variational iteration technique,the high-frequency gravity waves and short waves originally containedin the initial data can be considerably suppressed. The numericalresults show that this new scheme could avoid "kinetic energy loss"often found in other initialization procedures. Case studies indicatethat 24-hr forecasts of geopotential fields with the scheme are muchbetter than those with the original model, i.e., the balance equation. For instance, by using the scheme, the flaws of underesti-mating the intensity of closed highs and lows, troughs and ridges withthe original model can be remedied to a certain extent. In addition,the forecast 24-hr precipitation amounts are generally greater thanobtained by the original model but still smaller than the observedvalues.

Abstract:By using a two-level quasi-geostrophic spectral model in whichactual topography and diabatic heating are incorporated, blockingprocess in the northern hemisphere winter is numerically simulated.The results of the simulation account for the main features of ablocking process in the Atlantic and the Urals. Furthermore, a seriesof controlled experiments is carried out to reveal both the thermal andtopographic forcing in blocking processes, and the effects of theforcing intensity on the position, intensity and duration of theblocking highs.

Abstract:In view of the relatively poor accuracy of the estimates of cropyield in communities employed in agrometeorological work, a methodof correction is developed using the yield data at agricultural re-search institutes, state farms and seed-breeding fields. It can, in part,diminish the effect of artificial factors on the estimated crop yieldfigures for the communities. Also, an improved method is presentedfor yield decomposition by harmonic analysis and its advantagesare discussed through case studies.

Abstract:A new method is proposed for simultaneously deducing a numberof rain and wind parameters from vertically pointing Doppler radarmeasurements. By assuming an exponential shape for the raindrop sizedistribution, the intercept N₀, slope λ, vertical air velocity andspectral broadening due to shear and turbulence can be estimatedfrom measurements of the skewness of the Doppler spectrum (thethird center moment) and reflectivity.The primary advantage of thistechnique is that it is relatively insensitive to Doppler spectralbroadening due to wind shear and/or turbulence. An error analysisis made by use of simulated Doppler spectra. The skewness calculatedfrom real data shows a coherent property. The technique how toproperly select the λ values will be discussed further.

Abstract:Through a series of tests, we have examined the influence oflunar-terrestrial relation on precipitation during the rainy seasonover East China.The information used includes: the degree ofdrought or flood estimated from historical events in East China inthe past 500 years, the inferred indices of Meiyu and SummerDrought over the middle-lower Yangtze Valley for the past 100years, and the precipitation amounts and frequencies of rainstormsduring the rainy season over Jiangsu Province for the recent 30years. No significant statistical relationship between these data andthe lunar-terrestrial relation has been found. Systematic high corre-lations are also lacking between the Northern Hemisphere Summercirculation on the mean monthly 500mb charts and the lunar phases.Thus, we can conclude that lunar-terrestrial relation-though itstidal force might have some influence on the long-term fluctuationof certain climatic elements-has too small an effect to be considered in long-range forecasting.

Abstract:On the basis of FGGE Ⅲb data, the spatial distribution of 40-50day oscillations and features in their propagation over an extensiveregion (30°S-30°N, 30°E-150°W) during the summer of 1979 are dis-cussed in detail. The results confirm earlier investigations that theselow frequency modes are primarily associated with the zonal windoscillations. These 40-50 day perturbations propagate eastward and northward. However, the monsoon region is characterized by promi-nent spectral peaks in the 850 mb meridional winds with periodsshorter than 10 days, probably reflecting the activities of monsoondisturbances. At the equator,the 40-50 day zonal wind perturbationspropagate systematically eastward (600km/day) and upward (0.7km/day).The phase relationship between the zonal winds, geopotential heights,and large-scale apparent heat sources indicates that these equatoriallow frequency oscillations do not resemble atmospheric Kelvin waves.In contrast to what happens at the equator, the phase propagationof zonal wind perturbations along 15°N, although also being directedeastward, is not so systematic. At this latitude, zonal-wind pertur-bations are pronounced in the lower troposphere over the monsoonregion and also in the upper troposphere over the western Pacific.As an integral part of E-W interaction between these two regimes,there occurs downward progression of westerly (or easterly) pertur-bations over the Arabian Sea region. The downward phase of wes-terly (or easterly)modes corresponds to the commencement of "active"monsoons (or monsoon "breaks") over South and Southeast Asia.

Abstract:By analyzing the meridional component of the mean flow in theupper troposphere over the Northern Hemisphere, zonal distribution andseasonal variation of meridional circulation in the low latitudes areinvestigated. A statistical treatment of these features is presented. Ithas been found that there is correlation between ocean heating in Autumnand Winter and the ozone heating in Winter and Spring seasons andtheir interaction is discussed.

Abstract:Through a combined approach of growth analysis and field micro-climate observations, the variation of the utilization coefficient andtransfer efficiency of solar energy and the relationship between themfor various growth periods of two types of wheat crops are studied.An example of quantitative analysis, using the utilization coefficientof solar energy, of yield effect of cultivation practice is stated andan improvement on the current calculation of solar energy utilizationby wheat crops is presented. The experiment shows that the curveof variation of the utilization coefficient with respect to growingstage exhibits a double-hump distribution with a minimum occurringin the heading stage. For the same economical yield, the utilizationcoefficient of solar energy is larger in South China than in NorthChina. The benefit of using fertilizer is the net result of the com-bined effect of the transfer efficiency of solar energy, reflectanceand vegetative cover on the utilization coefficient of solar energy.