Eg Prior to the 1950s

Little is known about Eg# prior to the 1950s and since temperature changes then are well documented, such information could be valuable for understanding the influences of Eg# on climate. Stanhill and Cohen [18,19] used SSD data as proxies for Eg# based on recent simultaneous measurements of both measures, in order to deduce trends of Eg# from 1891 to 1987 for the US and from 1890 to 2004 for Japan. SSD was found to be well correlated with Eg# and therefore can serve as a proxy. The data from the US and Japan were from 106 and 65 stations with at least 70 and 35 a of data each, respectively. In the US mean SSD increased from 1891 to the 1930s and then decreased until the mid-1940s. In Japan a similar increase was observed from 1900 to the mid-1940s. This was followed by a decline until the late 1950s. Palle and Butler [22] found a decrease in SSD for four stations in Ireland for the period from 1890 to the 1940s. Sanchez-Lorenzo et al. [48] analysed SSD for the Iberian Peninsula for 1931 2004 and found a dimming trend from the 1950s to the early 1980s followed by brightening, but the early data (1931 1950) showed no clear trend. Thus, it is possible to obtain estimates of Eg# for the first half of the twentieth century and many SSD data sets exist, but more work is needed to understand this period.

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