• Korean Journal of Agricultural and Forest Meteorology
• /
• v.8 no.2
• /
• pp.116-124
• /
• 2006

Remarkable winter season warming has been observed in East Asian countries during the last century. Accordingly, significant effects on dormancy and the resulting budburst of deciduous trees are expected. However phenological observations are rare and insufficient compared with the long-time climate records in the same region. A chill-day accumulation, which can be estimated from daily maximum and minimum temperature, is expected to make a reasonable proxy for dormancy depth of temperate zone fruit trees. To simulate dormancy depth during 1921-2004, a chill-day model parameterized for 'Campbell Early' grapevine, which is the major cultivar grown virtually anywhere in South Korea, was applied to daily temperature data at 8 locations in South Korea. The calculations showed that the chilling requirement for breaking endo-dormancy of this grapevine cultivar can be satisfied by mid-January to late February in South Korea, and the date was delayed going either northward or southward from the 'Daegu-Jeonju' line crossing the middle of South Korea in the east-west direction. Maximum length of the cold tolerant period (the number of days between endo-dormancy release and forced dormancy release) showed the same spatial pattern. When we divide the 83 years into 3 periods (I: 1921-1950, II: 1951-1980, and III: 1981-2004) and get the average of each period, dormancy release date of period III was accelerated by as much as 15 days compared with that of period I at all locations except Jeju (located in the southernmost island with subtropical climate) where an average15-day delay was predicted. The cold- tolerant period was also shortened at 6 out of 8 locations. As a result, budburst of 'Campbell Early' in spring was accelerated by 6 to 10 days at most locations, while inter-annual variation in budburst dates was increased at all locations. The earlier budburst after the 1970s was due to (1) warming in winter resulting in earlier dormancy release (Incheon, Mokpo, Gangneung, and Jeonju), (2) warming in early spring accelerating regrowth after breaking dormancy (Busan and Jeju), and (3) both of them (Seoul and Daegu).

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.20 no.4
• /
• pp.321-329
• /
• 2018

A study was carried out to determine the influence of climatic environments on the growth characteristics and bulb quality of extremely early-maturing type onion grown at different altitudes, such as 60m, 200m, 350m and 700m above sea level (ASL). The mean air temperature during the growing season of extremely early-maturing type onion (October 18 to April 27) was $10.8^{\circ}C$, $9.6^{\circ}C$, $8.1^{\circ}C$ and $6.1^{\circ}C$ at 60m, 200m, 350m and 700m ASL. The mean air temperature during the bulb growth period (March 16 to April 14) was recorded $10.5^{\circ}C$, $9.4^{\circ}C$, $7.9^{\circ}C$ and $6.0^{\circ}C$ at 60m, 200m, 350m and 700 m ASL. Plant height, neck diameter, leaf number, leaf area, top fresh weight and top dry weight were significantly increased in growing of extremely early-maturing type onion at 60m ASL. Bulb/neck diameter ratio increased rapidly under the same temperature regime. The diameter and weight of the bulb were also the largest at 60m ASL during the bulb growth period (daily mean temperature of $12.5^{\circ}C$). At 60m ASL, there was the highest bulb size like a height, diameter and weight of bulb related directly on onion yield in the bulb growth period from March 16 to April 14. In contrast, yield and bulb quality were considerably decreased at 700m ASL during the bulb growth stage (daily mean temperature of $8.4^{\circ}C$). The quantity of extremely early-maturing type onion has gradually decreased as the daily average temperature drops below $12.5^{\circ}C$ during the bulb growth stage (March 16 to April 14). As a result, the lower temperature (daily mean temperature below $12.5^{\circ}C$) during the bulb growth stage significantly decreased the size and quantity of bulb in direction proportion.

• Journal of the Korean Geographical Society
• /
• v.43 no.3
• /
• pp.324-336
• /
• 2008

This paper examines the recent changes of summer precipitation in the aspect of temporal and spatial features using long-term($1958{\sim}2007$) observed station data over South Korea. tong-term mean summer precipitation has revealed two precipitation peaks during summer(June to September); one is the Changma as the first peak, and the other is the post-Changma as the second peak. During the Changma period, the spatial distribution of the maximum precipitation areas is determined by the prevailing southwesterlies and the quasi-stationary front, which results in large amount of precipitation at the windward side of mountain regions over South Korea. However during the post-Changma period, the spatial distribution of the maximum precipitation areas is determined by the lower tropospheric circulation flows from the west and the southeast around the Korean peninsula, and the weather phenomena such as Typhoons, convective instability, and cyclones which are originated from the Yangtze river. The larger amount of precipitation is founded on the southern coastal region and mountain and coastal areas in Korea during the second peak. Time series of total summer precipitation shows a steady increase and the increasing trend is more obvious during the recent 10 years. Decadal variation in summer precipitation indicates a large increase of precipitation, especially in the recent 10 years both in the Changma and the post-Changma period. However, the magnitude of change and the period of the maximum peak presents remarkable contrasts among stations. The most distinct decadal change occurs at Seoul, Busan, and Gangnueng. The precipitation amount is increasing significantly during the post-Changma period at Gangnueng, while the precipitation increases in the period between two maximum precipitation peaks during summer at Seoul and Busan.

• Journal of Mushroom
• /
• v.14 no.2
• /
• pp.39-43
• /
• 2016

In this study, we observed differences in the fruit body genesis in with seasonal changes. The mushrooms generated different spines even when under same environmental conditions in equivalent growth chambers during different seasons. The growth chamber conditions were set at $18^{\circ}$, 1000 ppm CO and 95% humidity for uniform primordium formation. Following this, the humidity was reduced to 85% during growth and development. The characteristics of the fruit body were measured: yield (weight), length (size), hardness, and chromaticity. Each measure was relatively compared owing standard data for. We investigated the environmental factors to assess the cause of variation in fruit body. Change in temperature and humidity were especially focused on, apart from climate that can affect mushroom growth. It was observed that temperature and humidity both influence fruit body growth. Not the absolute value of the elevation, there was a change of climate which the temperature is lowered and lowered the humidity can be assumed that the changes in the environmental conditions inside the growth chamber the mushroom growth.

• Korean Journal of Remote Sensing
• /
• v.28 no.5
• /
• pp.501-508
• /
• 2012

Albedo is known as a factor that directly impacts on the surface energy balance one of the elements of earth radiation balance. The change of albedo includes the change of soil moisture, vegetation, solar zenith angle, snow, and so on. In addition, it operates as a crucial path to understanding feedback mechanisms between radiation balance and its influence on climate and vegetation dynamics and therefore, observing the variation of albedo is a one of the essential procedures for anticipating climate change. In this study, we used MODIS 16-Day composited Albedo data from 2001 to 2011 years with the purpose of observing the change of albedo over Northeast Asia. According to the tendency of albedo for 11 years, albedo in the area of an active vegetation has increased in near-infrared (NIR) domain and decreased in visible (VIS) domain. On the basis of local changes in vegetation in 2002, the both area of the Gobi Desert and the Manchuria was enormously changed and chosen the research area and furthermore, the vegetation of both regions had deteriorated due to the change of the minimum value since 2010.

• Journal of the Korean earth science society
• /
• v.36 no.3
• /
• pp.199-209
• /
• 2015

The Atlantic meridional overturning circulation (AMOC), driven by high density water sinking around Greenland serves as a global climate regulator, because it transports heat and materials in the climate system. We analyzed the mechanism of AMOC on a decadal time scale simulated with the HadGEM2-AO model. The lead-lag regression analysis with AMOC index shows that the decadal variability of the thermohaline circulation in the Atlantic Ocean can be considered as a self-sustained variability. This means that the long-term change of AMOC is related to the instability which is originated from the phase difference between the meridional temperature gradient and the ocean circulation. When the overturning circulation becomes stronger, the heat moves northward and decreases the horizontal temperature-dominated density gradients. Subsequently, this leads to weakening of the circulation, which in turn generates the anomalous cooling at high latitudes and, thereby strengthening the AMOC. In this mechanism, the density anomalies at high latitudes are controlled by the thermal advection from low latitudes, meaning that the variation of the AMOC is thermally driven and not salinity driven.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.42 no.1
• /
• pp.41-49
• /
• 2014

This study spatially assesses the impact of trees on residential rooftop solar energy potential using urban three-dimensional models derived from Light Detection and Ranging(LiDAR) data in San Francisco, California. In recent years on-site solar energy generation in cities has become an essential agenda in municipal climate action plans. However, it can be limited by neighboring environments such as shade from topography, buildings and trees. Of all these effects, the impact of trees on rooftop photovoltaics(PVs) requires careful attention because improper situation of solar panels without considering trees can result in inefficient solar energy generation, tree removal, and/or increasing building energy demand and urban heat island effect. Using ArcMap 9.3.1, we calculated the incoming annual solar radiation on individual rooftops in San Francisco and the reduced insolation affected by trees. Furthermore, we performed a multiple regression analysis to see what attributes of trees in a neighborhood(tree density, tree heights, and the variance of tree heights) affect rooftop insolation. The result shows that annual total residential rooftops insolation in San Francisco is 18,326,671 MWh and annual total light-loss reduction caused by trees is 326,406 MWh, which is about 1.78%. The annual insolation shows a wide range of values from $34.4kWh/m^2/year$ to $1,348.4kWh/m^2/year$. The result spatially maps the locations that show the various levels of impact from trees. The result from multiple regression shows that tree density, average tree heights and the variation of tree heights in a neighborhood have statistically significant effects on the rooftop solar potential. The results can be linked to municipal energy planning in order to manage potential conflicts as cities with low to medium population density begin implementing on-site solar energy generation. Rooftop solar energy generation makes the best contribution towards achieving sustainability when PVs are optimally located while pursuing the preservation of urban trees.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.17 no.4
• /
• pp.340-347
• /
• 2015

This study was conducted to analyze the relationship between climate factors and fruit characteristics of 'Sangjudungsi' persimmon (Diospyros kaki THUNB) has been mainly cultivated in Sangju of Korea. We has been surveyed the yield and fruit characteristics such as fruit weight and soluble solids of 'Sangjudungsi' persimmon from 2010 to 2015 for five years. Also, as major meteorological factor, mean air temperature, cumulative temperature and days, the data of sunshine duration, diurnal range, and rainfall were collected from Sangju Regional Meteorological Administration. As result of that, the annual variation of fruit weight was affected by sunshine duration for April and October related starting point of fruit weight increase. The content of soluble solids was affected by sunshine duration for April and October similarly with fruit weight and was negatively correlated with the number of days with precipitation in the year. These results indicate the characteristics related to fruit quality like the above were affected by the sunshine duration and precipitation which is critical factor for the intensity of radiation during rapid growth period (April and October). Fruit number and yield per tree was commonly affected by mean air temperature of April and cumulative temperature days of October. These results also indicate that temperature for period of rapid growth stage of persimmon may have an important role in the fruit number and yield per tree.

• Journal of Environmental Impact Assessment
• /
• v.24 no.1
• /
• pp.1-15
• /
• 2015

To mitigate the impacts of climate change on agricultural ecosystems, development of agricultural management for enhanced soil carbon sequestration is required. In this study, the effects of fertilizer types (chemical fertilizer and manure compost), cropping systems, and crop residue management on SOC(Soil Organic Carbon) sequestration were investigated. Summer corn and winter barley were cultivated on experimental plots under natural rainfall conditions for two years with chemical fertilizer and manure compost. Soil samples were collected conducted and analyzed for SOC for soil. To estimate long-term variation patterns of SOC, DNDC was run with the experimental data and the weather input parameters from 1981 to 2010. DNDC simulation demonstrated SOC reduction by chemical fertilizer treatment unless plant residues are returned; whereas compost treatments increased SOC under the same conditions and SOC increment was proportional to compost application rate. In addition, SOC further increased under corn-barley cropping system over single corn cropping due to more compost application. Regardless of nutrient input type, residue return increased SOC; however, the magnitude of SOC increase by residue return was lower than by compost application.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.6
• /
• pp.51-59
• /
• 2014

Shallow landslides and debris flows are a common form of soil slope instability in South Korea. These events may be generally initiated as a result of intense rainfall or lengthening rainfall duration because of the effects of climate change. This paper presents the evaluation of rainfall-induced natural soil slope stability and reinforced soil slope instability under vertical load (railway or highway load) throughout South Korea based on quantitative analysis obtained from 58 sites rainfall observatories for 38 years. The slope stability was performed for infinite and geogrid-reinforced soil slopes by taking an average of maximum rainfall every ten years from 1973 to 2010. Seepage analysis is carried out on unsaturated soil slope using the maximum rainfall at each site, and then the factor of safety was calculated by coupled analysis using saturated and unsaturated strength parameters. The contour map of South Korea shows four stages in 10-year-time for the degree of landslide hazard. The safety factor map based on long term observational data will help prevent rainfall-induced soil slope instability for appropriate design of geotechnical structures regarding disaster protection.