1:45 PM - 3:15 PM
[O11-P14] Precipitation occurrence rates during the Dalton and Maunder Minimums, as determined by connecting the two diaries.
Keywords:multiple regression analysis, Dalton Minimums, Maunder Minimums
1.Motivation for research
This study focused on weather records in ancient documents as data that might allow us to investigate weather conditions prior to instrumental observations, taking a cue from the daily weather records in Dancyoteinichijo by Nagai Kafu, a great writer active from the Meiji to Showa periods. 11 ancient documents have been analyzed in the past 10 years (Fig.1). The Diary of the Hirosaki Domain in Edo (1668-1860, hereafter Hirosaki Domain) is an official record written at the clan's residence in Sumida-ku,Tokyo, and records events in the city of Edo.
2.Purpose of the study
To explore the weather in the Edo period by connecting the Ishikawa Diary and the Hirosaki precipitation occurrence rate and quantitatively reconstructing it.
3.Methods
We classified the weather in the historical documents to make the classifications closer to the definitions currently used by Japan Meteorological Agency and the weather was classified as snowy, rainy, cloudy, or sunny.
4.Data processing
The lengths of the weather records were the Ishikawa Diary was 177 years 70,071 days, and the Hirosaki Domain Edo Diary was 201 years 52,554days.
5.Detail rate
The detail rate is a proprietary function of Dr.Sho and is an indicator of the level of detail in the weather record, calculated as
(1)the number of days in which multiple types of weather are recorded,
(2)the number of days in which there are descriptions of temporal changes, and
(3)the number of days in which information on precipitation intensity such as heavy rainfall is included.The simpler the weather record, the less often the weather is observed, and the more likely it is that nighttime precipitation or small precipitation events are overlooked. The rate of detail in the Ishikawa Diary is higher than in previous studies.
6.Data and Discussion
Data(1) and Discussion: Distance between Tokyo Meteorological Observatory and Hachioji.
The straight line distance between Hachioji City and Tokyo Meteorological Observatory (Toranomon,Minato-ku) is about 39km.The correlation coefficient between precipitation rate of the weather station and precipitation rate of the diary was found to be 0.85, indicating a strong correlation, and we considered that the precipitation rates of the two locations could be compared (Fig.2). The weather records in the archives are qualitative and subject to errors when viewed on a daily basis, but when looking at the total values, they are considered to be materials that can be subjected to quantitative analysis.
Data(2) and Discussion: Restoration of the precipitation occurrence rate in Ishikawa Diary by multiple regression analysis
The coefficient of determination was 0.81 after multiple regression analysis using detailed rate x1 and precipitation rate in the diary x2 as explanatory variables and precipitation rate in the weather station y as the objective variable(Fig.3.4).
Data(3) and Discussion: Connecting two diaries and restoring the rate of precipitation occurrence in the Hirosaki Domain to find the causes of four famines in the Maunder Minimum period(Fig.5).
Four famines correspond to the years of increased precipitation occurrence: the Enpoh famine (1674-1675), the Enpoh 8 famine (1680), the Tenwa famine (1682-1683), and the Genroku famine (1691-1695) .
There are no quantitative previous studies on famine precipitation during the Maunder Minimum in Japan, but this study we believe that new data have been obtained(Fig.6).
7.Summary
(1)The straight line distance between Hachioji City and Toranomon, where the meteorological observatory was located, is about 39 km, and the correlation coefficient of precipitation rate is 0.85.
(2)When the two diaries are connected and the pre-1719 period of the Hirosaki Domain is reconstructed, the increase in the rate of precipitation occurrence corresponds to four famines.
8.Future Prospects
Using the Ishikawa Diary and Hirosaki Domain's reconstructed values, we will attempt to find diaries from the early Edo period written in the same Tokyo and reconstruct the weather conditions back in time.
This study focused on weather records in ancient documents as data that might allow us to investigate weather conditions prior to instrumental observations, taking a cue from the daily weather records in Dancyoteinichijo by Nagai Kafu, a great writer active from the Meiji to Showa periods. 11 ancient documents have been analyzed in the past 10 years (Fig.1). The Diary of the Hirosaki Domain in Edo (1668-1860, hereafter Hirosaki Domain) is an official record written at the clan's residence in Sumida-ku,Tokyo, and records events in the city of Edo.
2.Purpose of the study
To explore the weather in the Edo period by connecting the Ishikawa Diary and the Hirosaki precipitation occurrence rate and quantitatively reconstructing it.
3.Methods
We classified the weather in the historical documents to make the classifications closer to the definitions currently used by Japan Meteorological Agency and the weather was classified as snowy, rainy, cloudy, or sunny.
4.Data processing
The lengths of the weather records were the Ishikawa Diary was 177 years 70,071 days, and the Hirosaki Domain Edo Diary was 201 years 52,554days.
5.Detail rate
The detail rate is a proprietary function of Dr.Sho and is an indicator of the level of detail in the weather record, calculated as
(1)the number of days in which multiple types of weather are recorded,
(2)the number of days in which there are descriptions of temporal changes, and
(3)the number of days in which information on precipitation intensity such as heavy rainfall is included.The simpler the weather record, the less often the weather is observed, and the more likely it is that nighttime precipitation or small precipitation events are overlooked. The rate of detail in the Ishikawa Diary is higher than in previous studies.
6.Data and Discussion
Data(1) and Discussion: Distance between Tokyo Meteorological Observatory and Hachioji.
The straight line distance between Hachioji City and Tokyo Meteorological Observatory (Toranomon,Minato-ku) is about 39km.The correlation coefficient between precipitation rate of the weather station and precipitation rate of the diary was found to be 0.85, indicating a strong correlation, and we considered that the precipitation rates of the two locations could be compared (Fig.2). The weather records in the archives are qualitative and subject to errors when viewed on a daily basis, but when looking at the total values, they are considered to be materials that can be subjected to quantitative analysis.
Data(2) and Discussion: Restoration of the precipitation occurrence rate in Ishikawa Diary by multiple regression analysis
The coefficient of determination was 0.81 after multiple regression analysis using detailed rate x1 and precipitation rate in the diary x2 as explanatory variables and precipitation rate in the weather station y as the objective variable(Fig.3.4).
Data(3) and Discussion: Connecting two diaries and restoring the rate of precipitation occurrence in the Hirosaki Domain to find the causes of four famines in the Maunder Minimum period(Fig.5).
Four famines correspond to the years of increased precipitation occurrence: the Enpoh famine (1674-1675), the Enpoh 8 famine (1680), the Tenwa famine (1682-1683), and the Genroku famine (1691-1695) .
There are no quantitative previous studies on famine precipitation during the Maunder Minimum in Japan, but this study we believe that new data have been obtained(Fig.6).
7.Summary
(1)The straight line distance between Hachioji City and Toranomon, where the meteorological observatory was located, is about 39 km, and the correlation coefficient of precipitation rate is 0.85.
(2)When the two diaries are connected and the pre-1719 period of the Hirosaki Domain is reconstructed, the increase in the rate of precipitation occurrence corresponds to four famines.
8.Future Prospects
Using the Ishikawa Diary and Hirosaki Domain's reconstructed values, we will attempt to find diaries from the early Edo period written in the same Tokyo and reconstruct the weather conditions back in time.