• Journal of the Korean Geographical Society
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• v.41 no.3 s.114
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• pp.361-372
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• 2006

The purpose of this paper is to analyze temporal trends and spatial distribution of frost occurrence days using 54 weather stations under the Korea Meteorological Administration during the recent 30years ($1971{\sim}2000$). The frost occurrence days in the middle inland area was more than in the coastal area, but the period of free-frost days in the coastal area was longer than that in the middle inland. In the southern and eastern coastal areas, the frost day was more than in the western coastal area. The distribution of the first frost day was similar to that of the last frost day. The first frost day in the coastal area appeared a month later than that in the middle inland. The last frost day in the coastal area appeared $20{\sim}25$ days later than that in the middle inland. At most of stations which the first frost day was getting delayed and the last frost day earlier, the frost occurrence days showed a decreasing trend. However, in some stations, the frost occurrence day was increasing. As the frost days in October, March and April at some stations showed an increasing trend, the damage due to the frost might be increased in some areas in South Korea.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.2
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• pp.83-94
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• 2022

In order to actively prepare to frost damage that occurs in the process of growing crops, the spatial and temporal distribution of frost occurrence in South Korea was derived using frost observation data from 20 regions over the past 21 years (2000~2020). The main products are the number of frost days, first frost day, and last frost day by region. And the climatic trends of these results were identified by performing the Mann-Kendall trend test and Sen's slope estimator. In South Korea, a lot of frost occurs in the inland area to the west of the Taebaek and Sobaek Mountains. Relatively closer to the coastal area, the number of frost days is small, the first frost day is slow, and the last frost day is early. The east coast region has fewer frost days, the first frost day is later, and the last frost day is earlier than the west coast region. The southern sea, the southeastern sea region, and the island region rarely experience frost. As a result of the annual time series trend analysis, although South Korea is a country where climate warming is progressing, there was no trend in reducing the number of frost days and slowing the first frost day, and it was found that the last frost day is delayed by 0.5 days per year.

• Journal of Ecology and Environment
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• v.33 no.2
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• pp.121-131
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• 2010

Betula platyphylla var. japonica and Betula ermanii segregate vertically at an elevation of approximately 1,850 m on Mt. Neko in Nagano Prefecture, Japan. B. platyphylla var. japonica and B. ermanii were the dominant species below and above this altitude, at which the mean-annual and growing-season air temperatures were $4^{\circ}C$ and $14.1^{\circ}C$, respectively. Based on a modification of Kira's warmth index which employs cumulative temperature represented as $^{\circ}C$ day, leaf unfolding in both species was observed to be initiated at $58^{\circ}C$ day and $169^{\circ}C$ day, respectively. In 1996, leaf unfolding was initiated on 18 May in B. platyphylla var. japonica (+/-6 days) and on 5 June in B. ermanii (+/-8 days), shortly after the last frost which occurred on 5 May 1995 above 1,850 m; below this elevation there was no risk of frost at the time. At elevations above 1,850 m, the unfolded leaves of B. platyphylla were damaged by late frost, while B. ermanii escaped injury because the leaves were still protected by winter buds. The optimum temperature for seed germination in both B. platyphylla and B. ermanii was $30^{\circ}C$. Temperature alternation from 10 to $30^{\circ}C$ and moist storage of seeds at $4^{\circ}C$ (stratification) prior to incubation increased germination rates in both species. The seedlings of B. ermanii had a greater survival rates than those of B. platyphylla var. japonica when planted above 1,850 m. Comparisons of the timing of leaf unfolding and the latest frost at a site appeared to be the main factors affecting the vertical distribution of these species.

• Journal of the Korean Data and Information Science Society
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• v.27 no.1
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• pp.67-74
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• 2016

Due to the character of the climate of Korea, the pavement of a road is Influenced by freezing in winter season and thawing in thawing season. In the last few years, several articles have been devoted to the study to minimize the damage of freezing and thawing action. The purpose of this paper is to identify appropriacy of factors that influence road pavement thickness. We conduct the decision tree analysis on the field data of road pavement. The target variable is 'Frost penetration'. This value was calculated from the temperature data. The input variables are 'Region', 'Type of road pavement', 'Anti-frost layer', 'Month' and 'Air temperature'. The region was divided into 9 regions by freezing index $350{\sim}450^{\circ}C{\cdot}day$, $450{\sim}550^{\circ}C{\cdot}day$, $550{\sim}650^{\circ}C{\cdot}day$. The type of road pavement has three-section such as area of cutting, boundary area of cutting and bankin, lower area of banking. As the result, the variables that influence 'Frost penetration' are Month, followed by anti-frost layer, air temperature and region.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.32-37
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• 2013

Relationships among climate changes, early frost, and fruit growth were studied during the final month to harvest of late-maturing 'Fuyu' persimmon (Diospyros kaki) to assess the changes in fruit characteristics during this critical period. The heavy frost on Nov. 16 defoliated more than 70% of the leaves, but with little damage on the fruits. However, all the leaves were defoliated by the heavy frost on Nov. 20, and all the fruits were cold-damaged by $-3.3^{\circ}C$ on Nov. 21. Fruit weight increased by 8-25 g per week from Oct. 25 (142 days after full bloom) to Nov. 15, reaching to 250 g, but it decreased by 3-4 g per week after the frost. Hunter a value of fruit skin gradually increased until the last harvest on Nov. 29 with a temporary halt in early Nov. when temperature was high, whereas fruit firmness rapidly decreased after the frost on Nov. 21. Fruit soluble solids were $15.7-16.1^{\circ}Brix$ for the final month. When some branches were covered with non-woven fabrics to avoid direct contact with frost, the fruits on the branches were not visually damaged by the low temperature although 40-60% of their leaves were defoliated on Nov. 16. However, low temperature on Nov. 20 and 21 defoliated all the leaves, causing cold damage on the fruits. There was a highly significant correlation between the fruit diameter and its weight ($R^2$ = 0.73-0.91). So, the regression equations could be used to estimate weight from diameter of the fruits sampled from the branches with the non-woven fabrics. The calculated fruit weight reached to a maximum of 240 g on Nov. 15. Daily increases in fruit weight were 1.1-2.5 g from Oct. 25 to 31, 1.9-3.5 g from Oct. 31 to Nov. 7, and 1.4-1.6 g from Nov. 7 to 12. However, fruit weight decreased by 0.3-1 g per day after the cold damage on Nov. 21. The results indicate that the most appropriate harvest time could be dependent on relationship of fruit growth to climate.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.14
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• pp.53-64
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• 1973

The studies reported herein were conducted to investigate the effect of thermal conditions in double-cropping of rice. The accumulated daily mean and minimum air temperatures, for the period of the last 30 years, were examined at the 10 different meteorogical stations which are located in the southern part of Korea. The results obtained could be summarized as follows: 1. The first cropping. a. It seemed to be free from any frost-damage of rice at the seeding stage at Yeosu, Pusan and Cheju. However, it was found that there were some dangers of frost damage for about 30 to 40 day at Iri, Chonju and Kwangju, for 18 to 28 days at Daeku and Ulsan, and for 4 to 14 days at Mokpo and Pohang, respectively. b. The early critical transplanting date seemed to be from middle to late-April in the first cropping. As compared with the ordinary lowland seedlings, the semi-protected and upland ones could be planted 5 and 10 days earlier, respectively. c. The early critical heading date was about late-June and there were some low-temperature damages for 8 to 25 days at young-ear formation stage of rice plant, depending upon location. d. The early critical ripening date (the early critical transplanting date of the 2nd cropping) was from late-July to early-August. It took about 32 to 39 days in ripening. There was a tendency of SS${\fallingdotseq}$SL$15^{\circ}C$ (${\theta}$15) and the minimum of $10^{\circ}C$ (${\theta}$10), the ten locations could be devided into two ripening groups of ${\theta}$15>${\theta}$10 and ${\theta}$15<${\theta}$10. c. The late critical ripening date was around October 9 at Iri, Chonju, Kwangju and Daeku and around October 28 at Mokpo, Yeosu, Pusan and eheju. Three to four days were more required for a complete ripening of rice, as compared with the above dates. d. There was an overlap of about 12 to 42 days between the first and second cropping when early-maturing varieties requiring an accumulated mean air temperature of $1, 550^{\circ}C$, from transplanting to heading, were grown. Therefore, some varieties which could head with an accumulated daily mean air temperature of 1, 000 to $1, 200^{\circ}C$, should be either developed or some new cultural technology be established in order to have a successful double cropping in rice.