Monthly Frequency Distribution Research Articles

Statistical analysis of solar measurements in Algeria using beta distributions

A method of smoothing solar data by beta probability distributions is implemented in this paper. In the first step, this method has been used to process daily sunshine duration data recorded at thirty-three meteorological stations in Algeria for eleven year periods or more. In the second step, it has been applied to hourly global solar irradiation flux measured in Algiers during the 1987/89 period. For each location and each month of the year, beta probability density functions fitting the monthly frequency distributions of the daily sunshine duration measurements are obtained. Both the parameters characterising the resulting beta distributions are then mapped, enabling us to build the frequency distributions of sunshine duration for every site in Algeria. In the case of solar radiation for Algiers, the recorded data have been processed following two different ways. The first one consists in sorting the hourly global solar irradiation data into eight typical classes of the daily clearness index. The second one is based on the repartition of these data per month. The results of the first classification show that for each class of daily clearness index, the hourly data under consideration are modelled by only one beta distribution. When using the second classification, linear combinations of two beta distributions are found to fit the monthly frequency distributions of the hourly solar radiation data.

Impact of ENSO-Related Climate Anomalies on Crop Yields in the U.S.

Historical daily thermal and precipitation data from selected stations across the United States are composited into climate scenarios for the three phases of ENSO: Warm Events (El Nino), Cold Events (El Viejo or La Nina), and Neutral. Using these scenarios, yields of 7 field crops were simulated using the EPIC biophysical model during the one-year period coincident with maximum SST anomalies in the equatorial Pacific. The response of simulated agricultural productivity to the ENSO-related climate-variability parameters, is presented. A sensitivity calculation confirms the relevance of precipitation totals/medians and suggests ENSO-related yields are sensitive to changes in statistical properties characterizing precipitation distribution and occurrence. Results are spatially dependent, with the southwest and northern plains regions indicating the highest sensitivity to the inclusion of additional precipitation characteristics. The southeast yields are not as sensitive. The yield deviations (expressed as normalized differences to neutral yields) associated with the two extreme ENSO phases (Warm Events and Cold Events) are spatially and crop dependent with ranges up to ±120%. The largest yield deviations are in the south, southwest, and northern plains. Overall, Cold Events demonstrate larger impacts in the southern regions and Warm Events have a larger impact in the north. Additionally, the notion that climate anomalies associated with Cold and Warm Events and subsequent impacts on yields should be of opposite sign (i.e., linear) is not valid in many regions. For the eastern half of the U.S., modeled yield deviations under Warm Event conditions are nearly all less than neutral. Conversely, in the western half, results are more mixed. Under Cold Event conditions, yields in the east are enhanced in the south, but worsened in the north; while in the western half, yields have decreased in general. The results highlight the critical role of climate and production-related data on station or county levels in quantifying the impact of ENSO climate anomalies on yields. Both the diverse nature of the ENSO-related yield deviations as well as their sensitivity to monthly frequency distribution and occurrence characteristics imply that ENSO-related seasonal precipitation forecasts might be beneficial for agricultural application only if details were provided regarding not only totals, but also predicted changes in temporal and spatial variability of a more comprehensive suite of characteristics.

Wind energy potential assessment in Uttara Kannada district of Karnataka, India

Availability of wind energy and its characteristics at Kumta and Sirsi in Uttara Kannada District of Karnataka has been studied based on primary data collected at these sites for a period of 24 months. Wind regimes at Karwar (1952–1989), Honnavar (1939–1989) and Shirali (1974–1989) have also been analysed based on data collected from India Meteorological Department (IMD) of respective meterological observatories. Wind energy conversion systems would be most effective in these taluks during the period May to August. The monthly frequency distributions of wind speed have been analysed for Kumta and Sirsi where hourly wind speed recording is available. It is shown that two parameter Weibull distribution is a good representation of the probability density function for the wind speed. Energy Pattern Factor (EPF) and Power Densities are computed for sites at Kumta and Sirsi. With the knowledge of EPF and mean wind speed, mean power density is computed for Karwar, Honnavar and Shirali. Our analyses show that the coastal taluks such as Karwar and Kumta have good wind potential. This potential, if exploited would help local industries and coconut and areca plantations. Premonsoon availability of wind energy would help in irrigating these orchards and makes the wind energy a desirable alternative.

Screening of volatile substances and determination of toluene (a thinner component) in the blood and urine in emergency medical care and autopsy cases by the pulse heating method

Screening of volatile substances was performed by pulse heating gas chromatography — mass spectrometry (GC-MS) using a GS-Q column in 211 emergency medical care and 342 autopsy cases. At least 36 standard substances could be separately detected. Six kinds of volatile substances were screened in a total of 553 cases. Toluene and/or hippuric acid were detected in the blood and/or urine in respectively, 4 emergency medical care and 8 autopsy cases. There were 11 abusers (9 males and 2 females) in these 12 positive cases. The ages of the abusers ranged from 13–26 years. There was no particular pattern to the monthly frequency distribution of identification of thinner (toluene) abuse cases, which occurred throughout the year. It is believed that these data at least partly reflect the present status of thinner/glue abuse in Japan. We conclude that pulse heating GC-MS is useful in the screening and quantitative determination of volatile substances including toluene and other thinner/glue components.

Heavy rainfalls over East Asia

AbstractThe mean annual and monthly frequency distribution of heavy rainfalls for the period 1971–1980 are investigated over the whole of East Asia, including Japan, China, Korea, USSR, and Hong Kong. The highest frequency region (< 10 times per year) is shown to be located along the southern coast of Japan. The second highest region (< 8 times per year) is located along the southern coast of China. The high‐frequency area advances northward over China during the summer monsoon season, in accordance with the northward advance of the ‘Mei‐yü frontal zone’. Maps of the axes of high‐frequency heavy rainfall areas (frequency per 10‐day period) and of maximum‐frequency 10‐day periods at each station, clearly reveal the intra‐seasonal shift of the heavy rainfall area during the summer monsoon season.According to the dominant causes of heavy rainfalls, four regions are identified. The investigated area is also divided into three regions (I‐III) with respect to the annual frequency distribution of heavy rainfalls. Based on these regional divisions, the northern limit of the influence of the ‘Mei‐yü front’ is determined in terms of heavy rainfall occurrence.

Statistical Distribution of Solar Radiation: A European Data Set of Cumulative Frequency Curves of Solar Irradiance on Tilted Planes

The monthly frequency distribution of solar irradiance has now become a common meteorological input for solar energy system sizing methods, either directly or through the concept of “Utilizability”. Cumulative Frequency Curves (CFC) of solar irradiance were investigated within the frame of the European Solar Energy R and D Programme (Project F). The aim of this study was to prepare a European data set of CFC's for various typical climates and tilted planes. An algorithm for computing global irradiance on tilted planes has been validated, using 3 years of measured data on inclined planes at Carpentras. CFC's of global irradiance for 6 tilt angles at 12 European locations have been derived, using this algorithm and the “Test Reference Years” (TRY) hourly meteorological data base. CFC's are presented for each month in the form of parameters of an orthogonal polynomial fitting. La distribution statistique mensuelle de l'eclairement solaire est devenue aujourd'huiune entree meteorologique c1assique pour les me...

A New Thermal Rating Approach: The Real Thermal Rating System for Strategic Overhead Conductor Transmission Lines Part V Monthly and Annual Accumulative Frequency Distributions of Hourly Real-Time Thermal Rating and their Comparison with Conventional Rating-Risk Curves

A new method is introduced which tests the risk of any conventional ampacity rating derived from fixed value weather parameters. This method indicates that the risk of some commonly used ampacity ratings may be as high as fifteen percent, whereas in the past, normal probability methods applied to the wind velocity and ambient temperature data have shown the risk to be only .02 percent. This conflict is due to not recognizing the probability of wind direction and its associated magnitude. It is also shown that the real time capacity may reach 298 percent of the normal rating, while the minimum capacity is 72 percent of normal. Finally, it is found that the real time conductor temperature for fifty percent of the time is only 47 percent of the conductor temperature used to establish the normal rating, while the load is approximately 45 percent greater than the normal rating for fifty percent of the time.

BLOCKING HIGHS OVER THE EASTERN NORTH ATLANTIC OCEAN AND WESTERN EUROPE

Abstract The concept of blocking is briefly reviewed and a definition of “blocking High” in terms applicable to the daily sea level weather map of the eastern North Atlantic Ocean is adopted. The monthly frequency and geographical distribution of blocking Highs as defined are determined from forty years of Historical Weather Maps. Several features of these distributions are discussed in relation to observed monthly weather variations.

Some recent climatic changes in Washington, D.C.

The frequency of occurrence of clear and cloudy days in Washington, D. C., is compared for the intervals 1891–1920 and 1921–1950. There has been a steady increase of cloudy days, 36 more per year, and a decrease of clear days, 57 less per year. This change is reflected in all months of the year even though to a varying degree. The monthly frequency distributions show a statistically barely significant difference between the two intervals. This difference, in the light of collateral evidence, is, however, not attributable to chance. In conjunction with trends observed in temperature, dew point, and humidity values, only part of the change in cloud conditions can be ascribed to the growth of the city but is more likely due to the increasing maritime character of the climate in the northeastern United States.