Time Modeling of Daily UVB Values in Madrid, Spain

This paper presents the daily solar ultraviolet-B (UVB) values measured in Madrid, Spain, during the period 1994-97 with a Brewer MKIV spectrophotometer. The range of the measured Values was 0.042-6.41 kJ m(-2). A description of the values is shown. Periodicities of 7 and 3 days, associated with synoptic patterns, are significant. Ozone (with 5- and 3-day periodicities) and cloudiness also are studied for the same period; their association with UVB is investigated. The radiative amplification factor Value between UVB and ozone is 0.62. The correlation coefficient between UVB and a cloudiness index [equal to one minus the (number of sun hours divided by the number of theoretical sun hours)] is -0.57. A time series model describing the UVB series is shown. It is useful in estimating the UVB values, even on days when radiation values are not available. It provides accurate performance, can be used any day of the year, and has no main restrictions for its application. Thus, this kind of model can be a useful tool when modeling UVB behavior, complementing the information provided by other models.