نشریه نیوار
پیاپی 60-61 (بهار و تابستان 1385)

The socio-economic benefits of meteorological services in developing countries largely unrecognized. There appears to be general move from 1990’s in attention to management of production on the base of climatological data. Various studies show that the meteorological knowledge plays an important role in the designing, planning, control and operation. According to economic theory, the goods are classified to two groups, public good and private good. In short, a public good has the feature that one agent’s consumption of it does not affect the capacity of another agent to consume it. Then theconsumers don’t pay any fund and hereby the economists say that the groups of consumer take free rider. There are a number of rationalizations for government intervention to supply meteorological and other information services. Meteorologicalservices are part of the more general information system. Also, it is difficult in these circumstances for private producers to appropriate the benefits from producing the information or the public good. If private suppliers of meteorological information services, cannot appropriate the economic value of the service, then it is easily shown that if left to the private sector, the society will under invest in the production of the information service. The economic framework evaluating information services has progressed significantly since the development of ideas of cost-benefit ratios. The application of benefit matrix and conjugate matrix, using empirical formulation to carry out complex dynamic decision, mean value-based decision and climatic databased decision, queuing theory and finally the meteorological model of economic benefits in meteorological services are the techniques used in China. Various study in different countries showed that the benefit-cost ratio exceeds 5, 10, 20 and 30 even 40 to 1. If we ignore this important factor in the economy, that we can call it treasure of green gold, therefore undoubtedly this may lead to slow the process of development. It is necessary to recognize the methods of economic and introduce the techniques used for evaluation of economic and social benefits and pricing the meteorological products in considering commercialization and privatization policy and user pay principle.

The wind-chill index is a cooling rate according to wind and low temperature combining effect. In other words it indicates that how the human body cools down under certain combinations of wind and temperature. We feel colder during a cold blowing wind wintry day as compared to a day when there is no wind at all, although the temperature may be the same at the both days. Therefore the wind-chill index can be a good indicator of our feeling about outside coldness and helps us to decide what to wear or about canceling our outdoor activities. Low wind-chill rates are along with some dangers, among which one of them is hypothermia. Under these conditions the inner body temperature decreases to a level at which muscles and brain are impaired. In some countries wind-chill index is applied, the forecast is issued when this index is reached to a point in which the frost bit happens and warning is issued when conditions are dangerous. Using this index is easy and we can apply it. Country meteorological organization also can issue forecast and warning when weather condition is hazardous, through radio and TV broadcasts. In this paper the windchill formula efficiency and applying is evaluated.

In this research, in order to consider the freezings which occurred in Ekbatan (Hamedan) station, minimum daily temperatures of this station were studied. that in generally freezings were divided to 3 levels: weak-freezing, middlefreezing and intense-freezing. Then, we determined the range of temporal changes and the abundance of the freezing. Also we have tried to introduce a model which can forecast the date of first autumnal freezing according to the date of last spring freezing. By calculating different statistical parameters, probability of occurrence the temperature thresholds between –15 to 0 (oc) were determined for different months. In addition to this, by dividing the year to 36 different periods of ten days, we have tried to calculate temperature of different probability percents. The result indicate that the minimum temperature in this station has been increasing during past two decades and Isfand and Ordibehesht have shown the most and the least rate of temprature, respectively. Sever freezing periods in day and bahman, the moderate ones during Mehr, Aban, Bahman and Esfand and the mild ones during Aban take place. In order to predict freezing during autumn amodel has been proposed by which an appropriate linear correlation between freezing in autumn and the one in spreang is shown. By means of spring freezing the history of autumn freezing can be predicted. This model is meaningful at the level of 5%.

Enso is a combination of two words El-Nino and Southern-Oscillation and this phenomena is on of the major Teleconnection pattern in the Southern Hemisphere, which affects the climate of World by means of changing the patterns of pressure, temperature, rainfall and …. The impact of this on its different warm and cold phases on the patterns of pressure, temperature and rainfall of different parts of World, including Iran, has been observed and there have been signification differences among them. But, since each region of earth reaction is different facing ENSO, and is done with different lags, in this Article, the relationship between ENSO and monthly and seasonal rainfall of Shahr-ekurd has been studied. In this Article, the relationship between these two patterns based on the 44-year period (1957-2000) of rainfall of Synoptic station of Shahr-e-kurd, and the SST in Nino 3.4 zone has been studied. The results of this survey shows that during this statistical period, the rainfall pattern of Shahre- kurd in months: May, June, August, October, and November links with ENSO, which the amount of this relationship is even different in the mentioned months. So, the correlation ENSO with monthly rainfall pattern of Shahr-e-kurd is most noticeable in turn in months: June, May (spring) October and November (Autumn). According to these results, we also noticed that, basically, correlation between ENSO and the rainfall of Shahr-e-kurd is negative. The results show that the most relationship between the SST in Nino 3.4 zone and the rainfall of Shahr-e-kurd is noticed with 4-month delay.

Forecasting of the nacturnal minimum temperature has a special importance and the most usage of it is in agricultural affairs. The first step in forecasting the nacturnal minimum temperature is forecasting the surface temperature. Forecasting of the surface temperature is carried out by meteorological factors using equilibrium of surface energy method. In this study, it is developed a model with using of surface energy equation and The surface temperature was forecasted based on model. Results indicats,while vertical velocity increases, vertical heat flux increases too and it one of the reason to decrease surface temperature. In addition, If The solar radiation is decreased, surface tempreture decreased too. The cloudy sky and visible are effective factors in decrease solar radiation. The values and out puts of the model, have been compared with one hour field observation and it is found out difference between them. As regards that there are error sources in calculation, results are difference. In order to creating network and calculate have been used of Geophysics station that is one of the most importance reasons importance different of result. Recent station distance until shemiran station is very high for calculate surface and screen temperature. The determination of correct values related with temperature will be followed by correct estimate of surface temperature.