About 100 years survey of the surface temperatures of Japan sea and lightning days along the coast

On the website of the Japan Meteorological Agency, various weather data are shown. This paper has surveyed the hundred years data of the surface temperatures of Japan Sea and the number of lightning days in cities along the Japan Sea coast. The sea surface temperatures have increased by 1.2 °C to 2.2 °C in the last hundred years, and correspondingly the number of lightning days has increased by 20 to 45 days in the last hundred years. The correlation coefficient for winter lightning shows rather high dependence of the lightning days on the sea temperature in the cities located in a high latitude.