『승정원일기』와『일성록』의 조선후기 측우기록 분석 및 <한양우량표>(1770-1907)와 <서울 250년간 우량표> 개발 연구

Abstract

This study focuses on the recovery of the authentic records of Chukwookee rainfall sourced from the two historical material: Diary of the Royal Secretariat (Sungjungwon) and Court Chronicle (Ilsung-rok). The unprecedented development of Hanyang Rainfall Chart (1770-1907) for the 238 years of late Joseon dynasty (1392-1910) came out along with this study. Despite the significant value of the pluviometer (Chukwookee) and its daily in meteorological studies, verification works for the historical records have remained long ignored. Thus, till today lacking the authenticity of real records, Wada Yuji’s Gyeong Jeong Rainfall Chart (1914) has been used as is. Both the Central Meteorological Service and the academia meteorology are depending on Wada’s chart costing the demise of the knowledge about the true historical records of rainfall. This study came to prove that Wada’s chart is largely discrepant from the real records and thus error-stricken. Wada’s miscalculated measures exceed by 141.2% and 152.9% respectively the real numbers shown in the Diary of the Royal Secretariat and Court Chronicle. By introducing the detailed information on rainfall from the two classic material, it came to shed light on the dearth of fundamental research in the academia of Korea. The main material Diary of the Royal Secretariat contains 8,820 articles and 7,141 days (annual average 51.7 days) of rainfall records and a total 155,310mm (annual average 1,125mm) of rainfall during the 138 years (1770-1907). The supplementary material Court Chronicle contains 6,702 articles and 6,649 days (annual average 51.9 days) and total 143,496㎜ (annual average 1,121.1㎜) during the 132 years (1776-1907). The Diary of the Royal Secretariat provides hour-based records in detail, and Court Chronicle provides accumulated daily records. The second book thus plays an important role to fill in some missing parts of the main material. The consolidation of the two books resulted in a new development of Hanyang Rainfall Chart. The new data appeared with a total 9,312 rainfalls, 7,587 (annual average 55) rainy days, and a total 165,824㎜ (annual average 1,201.6 ㎜) rainfall during the 138 years (1770-1907). Thanks to the new chart, a meteorological analysis of rainfall in Hanyang in the late Joseon period is completed. This chart displays the monthly rainfall tendency of that period in parallel with the modern period. Thus further it proves the credibility of the historical meteorological records of Joseon dynasty. One of the most intriguing revelations is that the year with double leap months shows a 9% increase of annual average rainfall compared with normal years. This is considered as one of the most peculiar meteorological phenomena of rainfall. When this issue was cross examined against the modern period (1908-2019) the same type of peculiarity appeared with a 5% increase in the year with double leap months compared with normal years. A comprehensive study is conducted on this issue of peculiarity on the 250 years (1770-2019) of Seoul history. The outcome was 7% increase. Concerning the decrease, the previous year (-8.8%) appeared greater than the following year (-6.6%). With the confirmation of credibility of the historical records, another development of extended chart is designed to be connected and continuous to modern period. Thus the 250 Years of Seoul Rainfall Chart (1770-2019) came to exist as to become the longest period data for further discovery of various aspects of rainfall. According to the ten-year-interval diagram the annual rainfall and the summer rainfall go in parallel in M shape. The 50-year-interval diagram displays two open-wing shapes, which include 1)the first drought in the late 18C, 2)the first wet climate in the first half 19C, 3)the decrease of rain in the second half 19C, 4)the second and more serious drought in the first half 20C, 5)the second and more wet climate in the second half 20C, and 6)sharply increased summer rain in the early 21C and the tendency to continue to increase. These variations clearly show their connection to the present abnormal climate changes. The rainy season out of the 366 days including the leap day is drawn by the accumulated daily rainfalls as follows: First, the 30 days of rainy season (6.25∼7.24). Second, the 16 days of wet climate (7.27∼8.11). Third, the 21 rainy days of wet climate (8.16∼9.05). The whole 73 days of summer and autumn (6.25∼9.05) show the features of Korean style rainfall. It is also noted that during the 138 years some days were marked as the Day of No Rain, which included January 3rd and February 3rd. The day with the heaviest rain of the year was marked as the Day of Rain on July 16th. Having developed a rainfall chart of the longest period, it is hoped that this study will inform the world the excellence of the pleviometer and contribute to the enrichment of rainfall studies in historical meteorology.