Elsevier

Energy

Volume 27, Issue 10, October 2002, Pages 947-954
Energy

Generation of a typical meteorological year using sunshine duration data

https://doi.org/10.1016/S0360-5442(02)00029-4Get rights and content

Abstract

In this paper, we discuss the possibility of using the daily sunshine duration or the daily sunshine duration over day-length data instead of daily global solar radiation in order to develop a Typical Meteorological Year, TMY2, for localities with abundant data of daily sunshine duration. The analysis is done using the latest methodology proposed in the literature. The number of coinciding months is about 40% when daily sunshine duration or the daily sunshine duration over day-length data is used instead of daily global solar radiation as one of the parameters in obtaining TMY2. Such a relatively low figure is probably due to the unreliable solar radiation data recorded by Robitzch-type actinographs used in the present work.

Introduction

Accurate prediction of the long-term performance of solar systems, such as photovoltaic applications, active and passive heating and cooling, depends on the long-term climatic features at a location. The need for one-year performance calculation of such systems led to the development of a Typical Meteorological Year (TMY) [1], [2], [3] or Test Reference Year (TRY) [4], [5], [6], [7] or Design Reference Year (DRY) [8].

At present there are several methods for the generation of a TMY. In chronological order, they are:

  • •

    Danish method by Anderson et al. [8] in 1977 and by Lund and Eidorff [5] in 1981;

  • •

    Sandia National Laboratory method (TMY) presented by Hall et al. [1] in 1978;

  • •

    Festa Ratto method [9] in 1993;

  • •

    TMY2, which is a modification of the original Sandia method by Marion and Urban [10] in 1995.

A study has been carried out [11] for the generation of a TRY using the meteorological data of Turkey as the first effort. In this work [11], the global radiation data were estimated by a model described in Ref. [12], using daily sunshine duration data.

In this paper the TMY2 method is applied due to its large acceptance in USA and Canada where the method is applied to 239 stations. TMY2 method utilizes nine daily parameters; the eight of these daily parameters used for the selection of the typical months consist of the maximum, minimum, and mean dry-bulb air temperature, the maximum, minimum, and mean relative humidity, the maximum and mean wind velocity. The ninth parameter used in the analysis is daily global solar radiation. In this paper, one of the following four variables was examined to be the ninth parameter in the procedure: the daily global solar radiation, the measured daily bright sunshine duration, the daily bright sunshine duration over day-length, and the ratio of daily global to extraterrestrial daily global solar radiation. The reason for such a test is the abundant sunshine recording stations (70) in Turkey compared to the few stations recording solar radiation data using accurate instruments.

Section snippets

Description of the methods

The Danish method [5], [8], which will not be presented in detail here, uses a three-step procedure for the selection of the months that will be considered in the TRY. The method uses daily meteorological data such as the average temperature, maximum temperature, relative humidity, wind speed, atmospheric pressure, sunshine duration, and global solar radiation in one of the steps, whereas daily average temperature, daily maximum temperature, daily global radiation, and daily sunshine duration

TMY2s for Ankara

Eight daily parameters used for the selection of the typical months consist of the maximum, minimum, and mean dry-bulb air temperature, the maximum, minimum, and mean relative humidity, the maximum and mean wind velocity. As for the ninth parameter, daily global solar radiation (H) or daily sunshine duration (s) is used. The relation between the ratio of the measured sunshine duration to the day-length (s/S) and the ratio of daily global solar radiation to extraterrestrial daily solar radiation

Data used in the analysis

The data of Ankara covering the period 1979–1999 was obtained from the Turkish State Meteorological Service (TSMS). The candidate months of TMY2 were determined using the daily data obtained from hourly values. The missing data, accounting for 1% of the whole database, were completed by taking the arithmetic mean of the values of previous and next days. The radiation data were taken from Robitzch-type actinographs, the dry-bulb temperature from thermometers, the relative humidity from

Results and discussion

We should point out that although the accuracy of Robitzch-type actinography data is 20% there still exists a correlation between the daily sunshine duration and daily global solar radiation data taken by this instrument. The reason for such a correlation is because of the effective role of systematic errors in the overall accuracy of the Robitzch actinographs.

A statistical analysis is done to see how closely does s represent H as the ninth parameter in obtaining TMY2s. The variables considered

Conclusion

The possibility of using the daily sunshine duration or the ratio of the daily sunshine duration to the day-length instead of daily global solar radiation, as the ninth parameter, in the generation of the TMY is analyzed. The analysis aims at locations with abundant data of daily sunshine duration where long-term data of daily global solar radiation is lacking. However, due to the unreliable solar radiation data recorded by Robitzch-type heliographs, the accuracy in obtaining the TMY is not as

References (14)

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