Spatial and Temporal Trends in High Resolution Gridded Temperature Data over India

Grace Nengzouzam,Sanayanbi Hodam,Arnab Bandyopadhyay,Aditi Bhadra 한국기상학회 2019 Asia-Pacific Journal of Atmospheric Sciences Vol.55 No.4

The changing temperature, directly and indirectly, has significant effect on the agricultural production and economy of the country which necessitates detailed study of the spatial and temporal variability of temperature. This paper focuses on the spatio-temporal trend analysis of minimum and maximum temperature over India. Daily gridded temperature data with spatial resolution of 1° × 1° for the period of 1969–2005 were analysed using Mann-Kendall (MK) non-parametric test at 3 levels of significances, namely, 1%, 5%, and 10%. The diurnal temperature range was also analysed. Results showed that maximum temperature experienced significant decreasing trends in the entire Indo-Gangetic plains extending up to the NE region while the Southern region experienced warming. For minimum temperature, all regions except the Central region reported increasing trends indicating warming. As a result, diurnal temperature range showed decreasing trends in many places in the upper half of the country while the lower half is dominated by increasing trends. On a regional scale, the Southern region, in particular, showed increasing trends in all three parameters. On seasonal scale, pre-monsoon and monsoon months remained mostly trendless for all three parameters. Maximum significant decreasing trends were observed during January–May while maximum increasing trends were reported during June–December. Also, a higher Sen slope value of the yearly maximum increase in the minimum temperature indicated steeper increase in minimum temperature over maximum temperature.

Errors in Estimated Temporal Tracer Trends Due to Changes in the Historical Observation Network: A Case Study of Oxygen Trends in the Southern Ocean

Min, Dong-Ha,Keller, Klaus Korea Institute of Ocean ScienceTechnology 2005 Ocean and Polar Research Vol.27 No.2

Several models predict large and potentially abrupt ocean circulation changes due to anthropogenic greenhouse-gas emissions. These circulation changes drive-in the models-considerable oceanic oxygen trend. A sound estimate of the observed oxygen trends can hence be a powerful tool to constrain predictions of future changes in oceanic deepwater formation, heat and carbon dioxide uptake. Estimating decadal scale oxygen trends is, however, a nontrivial task and previous studies have come to contradicting conclusions. One key potential problem is that changes in the historical observation network might introduce considerable errors. Here we estimate the likely magnitude of these errors for a subset of the available observations in the Southern Ocean. We test three common data analysis methods south of Australia and focus on the decadal-scale trends between the 1970's and the 1990's. Specifically, we estimate errors due to sparsely sampled observations using a known signal (the time invariant, temporally averaged, World Ocean Atlas 2001) as a negative control. The crossover analysis and the objective analysis methods are for less prone to spatial sampling location biases than the area averaging method. Subject to numerous caveats, we find that errors due to sparse sampling for the area averaging method are on the order of several micro-moles $kg^{-1}$. for the crossover and the objective analysis method, these errors are much smaller. For the analyzed example, the biases due to changes in the spatial design of the historical observation network are relatively small compared to the tends predicted by many model simulations. This raises the possibility to use historic oxygen trends to constrain model simulations, even in sparsely sampled ocean basins.

Analysis of Spatial-temporal Variability and Trends of Extreme Precipitation Indices over Chungcheong Province, South Korea

Bashir, Adelodun,Golden, Odey,Seulgi, Lee,Kyung Sook, Choi The Korean Society of Agricultural Engineers 2022 한국농공학회논문집 Vol.64 No.6

Extreme precipitation events have recently become a leading cause of disasters. Thus, investigating the variability and trends of extreme precipitation is crucial to mitigate the increasing impact of such events. Spatial distribution and temporal trends in annual precipitation and four extreme precipitation indices of duration (CWD), frequency (R10 mm), intensity (Rx1day), and percentile-based threshold (R95pTOT) were analyzed using the daily precipitation data of 10 observation stations in Chungcheong province during 1974-2020. The precipitation at all observation stations, except the Boryeong station, showed nonsignificant increasing trends at 95% confidence level (CL) and increasing magnitudes from the west to east regions. The high variability in mean annual precipitation was more pronounced around the northeast and northwest regions. Similarly, there were moderate to high patterns in extreme precipitation indices around the northeast region. However, the precipitation indices of duration and frequency consistently increased from the west to east regions, while those of intensity and percentile-based threshold increased from the south to east regions. Nonsignificant increasing trends dominated in CWD, R10 mm, and Rx1day at all stations, except for R10 mm at Boeun station and Rx1day at Cheongju and Jecheon stations, which showed a significantly increasing trend. The spatial distribution of trend magnitude shows that R10 mm increased from the west to east regions. Furthermore, variations in precipitation were very strongly correlated (99% CL) with R10 mm, Rx1day, and R95pTOT at all stations, except with wR10 mm at Cheongju station, which was strongly correlated with a 95% CL.

충청지역 극한강우지수의 시공간적 경향과 변동성 분석

바실 아델로둔,최경숙,이슬기,골든 오데이 한국농공학회 2022 한국농공학회논문집 Vol.64 No.6

Extreme precipitation events have recently become a leading cause of disasters. Thus, investigating the variability and trends of extreme precipitationis crucial to mitigate the increasing impact of such events. Spatial distribution and temporal trends in annual precipitation and four extreme precipitationindices of duration (CWD), frequency (R10 mm), intensity (Rx1day), and percentile-based threshold (R95pTOT) were analyzed using the dailyprecipitation data of 10 observation stations in Chungcheong province during 1974–2020. The precipitation at all observation stations, except theBoryeong station, showed nonsignificant increasing trends at 95% confidence level (CL) and increasing magnitudes from the west to east regions. Thehigh variability in mean annual precipitation was more pronounced around the northeast and northwest regions. Similarly, there were moderate to highpatterns in extreme precipitation indices around the northeast region. However, the precipitation indices of duration and frequency consistently increasedfrom the west to east regions, while those of intensity and percentile-based threshold increased from the south to east regions. Nonsignificant increasingtrends dominated in CWD, R10 mm, and Rx1day at all stations, except for R10 mm at Boeun station and Rx1day at Cheongju and Jecheon stations,which showed a significantly increasing trend. The spatial distribution of trend magnitude shows that R10 mm increased from the west to east regions. Furthermore, variations in precipitation were very strongly correlated (99% CL) with R10 mm, Rx1day, and R95pTOT at all stations, except with wR10mm at Cheongju station, which was strongly correlated with a 95% CL.

Long-term Changes of Physicochemical Water Quality in Lake Youngrang, Korea

Bal Dev Bhattrai,Sungjin Kwak,Kwansoon Choi,Woomyung Heo 한국수생태학회(구 한국하천호수학회) 2017 생태와 환경 Vol.50 No.1

Physicochemical properties of water quality were analyzed to understand the long-term variations in Lake Youngrang from 1998 to 2015. Nonparametric statistical methods were applied to deduct correlation among water quality parameters and water quality trend. In total observations (N=64), the Secchi depth (SD) transparency showed significant positive correlation with salinity (r=0.458) and highly significant negative correlation with chlorophyll-a (r= - 0.649) for p<0.0001 in two-tailed test of Spearman’s rank correlation. Significant negative correlations of SD were observed with chemical oxygen demand (COD), total phosphorus (TP) and total nitrogen (TN). These correlation patterns were very similar in rainy (N=25) and non-rainy (N= 39) periods too. Chlorophyll-a (Chl-a) had significant correlation with COD. Sen’s slope test was performed along with Mann-Kendall trend test (significance α=0.05, two-tailed) to find water quality trend. Positive trends were observed for SD and salinity with Sen’s slopes 0.012 and 0.385, respectively (p<0.0001). Negative significant trends were observed for total nitrogen (TN) and Chl-a with Sen’s slopes - 0.02 (p<0.0001) and - 0.346 (p=0.0010), respectively. Temperature, COD and phosphorus components had no trends. Carlson’s trophic state index (TSI) for SD, TP and Chl-a were obtained in the ranges of 46~80, 37~82 and 39~82, respectively. Trophic index values suggest that Lake Youngrang was mesoeutrophic to eutrophic and there could be possibility of anoxia during the summer and dominance of blue-green algae. Excess nutrient inputs from external and internal sources were the causes of eutrophication in this lake. The findings of this study would be helpful to recognize water quality variables to manage the water body.

한국 사회의 교육적 동질혼: 시계열 추세 및 그 함의

박현준,김경근 한국교육사회학회 2011 교육사회학연구 Vol.21 No.3

Drawing on marriage registration data, this study examines temporal trends from 1993 to 2007 in educational homogamy in South Korea. Most previous studies of educational homogamy in South Korea did not compare cohorts based upon years of first marriage but only birth-year cohorts, which is a significant limitation in exploring temporal trends. The current study overcomes this limitation by investigating trends in educational homogamy on the basis of first-marriage couples classified according to their marriage years. More importantly, this research covers the period (1993-2007) of rapid changes in Korean society, providing most updated analysis of educational homogamy. Applying log-linear and log-multiplicative models, the study finds a rapid decline during the 1990s followed by a much slow decline during the 2000s in the strength of association between spouses' educational attainment, which is in part likely attributable to modernization, the increased opportunity of higher education for women due to educational expansion, and the decrease in economic return to professional jobs. The continued decline in educational homogamy is in sharpe contrast to the expectation that increased economic inequality and other social changes during the period should have strengthened the degree of educational homogamy, requiring further systematic research. However, it is important to note that the decline in educational homogamy does not necessarily mean the growing openness of Korean society because declining educational homogamy might have occurred simultaneously with the growing impact of family background on marriage. 본 연구에서는 1993년부터 2009년까지 접수된 혼인 신고서를 이용하여, 1990년대 초반 이래 한국사회에서 교육적 동질혼 경향이 어떻게 변화해 왔는지 살펴보았다. 그간 한국에서 수행되었던 대부분의 관련 연구들은 초혼에 기반을 둔 결혼 코호트를 구성하지 못함으로써 시계열 추세를 분석하는 데 일정한 한계를 가졌다. 그런데 본 연구는 초혼/재혼을 구별하고 출생 연도가 아닌 결혼 연도를 이용해 결혼 코호트를 구성함으로써 선행연구들의 제한점을 극복하였다. 아울러 본 연구는 활용 가능한 최신 자료를 사용함으로써, 역동적인 한국 사회에서 교육적 동질혼이 최근에 어떤 양상으로 진행되고 있는지를 시의성 있게 보여주고 있다. 분석 결과, 1993년부터 2007년 사이에 부부 간 학력의 연관성이 지속적으로 완화되어 왔음이 밝혀졌다. 교육적 동질혼의 약화 추세는 1990년대에 보다 뚜렷하고, 2000년대에 들어서면서 다소 완화된다. 이처럼 예상과 달리 근자에 교육적 동질혼 경향이 약화되고 있는 현상의 배경은 후속 연구를 통해 좀 더 엄밀하게 구명될 필요가 있지만, 다양한 근대화의 과정, 교육팽창에 따른 여성 교육기회의 신장, 학력 가치의 하락 등이 일정 정도 기여를 했으리라 짐작된다. 한국 사회에서 나타나고 있는 교육적 동질혼의 약화는 귀속적 지위를 중심으로 한 동질혼의 강화를 수반하고 있을 개연성이 크기 때문에 사회 전반의 개방성 증대로 해석하기에는 무리가 있다.

Spatial and temporal trends of per- and polyfluoroalkyl substances (PFASs) in the coastal waters of Korea during 2013-2020

Hyun-Kyung Lee(이현경),Jae-Won Lee(이재원),Jae-Eum Lim(임재은),Hyo-Bang Moon(문효방) 환경독성보건학회 2021 한국독성학회 심포지움 및 학술발표회 Vol.2021 No.5

Per- and polyfluoroalkyl substances (PFASs) are a complex family of > 5,000 man-made fluorinated organic chemicals with hydrocarbons. They are also referred to as forever chemicals as substances that are extremely difficult to remove because of a greater persistence in the environment. In this study, PFASs were measured for seawater, sediment, and bivalves collected from 50 locations along the Korean coast during 2013-2020 to investigate the occurrence, spatial distribution, and temporal trends. The concentrations of perfluoroalkyl acids (PFAAs) in seawater, sediment, and bivalves were detectable in all samples, ranging from 1.76 to 7.40 ng/L, 0.18 to 0.51 ng/g dry weight (dw), and 4.41 to 12.9 ng/g dw, respectively. Higher concentrations of PFASs were observed in multiple environmental samples at the locations near highly industrialized regions, which were characterized by industries producing semi-conductors, steels, chemicals, electronics and automobiles. Matrix-dependent spatial distributions of PFASs were observed for seawater, sediment, and bivalves. For all samples, locations and years monitored, PFOS and PFOA were major PFASs due to high consumption and greater persistence in coastal environment. Total concentrations of PFAAs increased gradually from 2013 to 2016/2017 and then were stabilized without changes in PFAS compositions. The concentrations of short-chained PFASs increased gradually in seawater samples. Moreover, the highest concentrations of PFBA were observed at the locations from Yellow Sea, which was contained high-tech industries. Our results indicate a shift in PFAS consumption patterns from C8-based PFAS toward shorter-chained PFASs in Korean industries. More scientific attentions are required concerning ecotoxicological implications of shorter-chained PFAS, such as PFBA and PFBS, to dwelling species in Korean coastal waters.

최근 한국의 서리 현상의 공간 분포와 시계열 변화 경향

권영아(Kwon Young-Ah) 대한지리학회 2006 대한지리학회지 Vol.41 No.3

최근 30년간(1971~2000년) 54개의 전국 기상관측 지점의 서리 현상 자료를 이용하여 공간 분포와 시계열 변화 경향을 분석하였다. 서리 현상일수는 내륙이 많고 해안으로 갈수록 적은 반면, 무상기간은 내륙이 짧고 해안이 길다. 남해안과 동해안이 서해안에 비해 서리 현상일수는 적고 무상일수는 많다. 서리 시작일과 종료일도 경향이 비슷한데 내륙 지역의 첫 서리일은 10월 상순으로 해안 지역보다 한 달 빠르며, 마지막 서리일은 4월 하순으로 해안 지역보다 20~25일 정도 늦다. 첫 서리일이 늦어지고 마지막 서리일은 빨라지는 경우 대부분 지점들은 서리 현상일수가 감소하였으나, 증가하거나 변화가 없는 지점들도 있었다. 반면, 첫 서리일은 빨라지고 마지막 서리일은 늦어지는 경우에 해당하는 지점들은 모두 서리 현상일이 증가했다. 서리 현상일수가 증가한 지점들의 월별 변화를 보면 11월과 3월, 4월이 증가하는 경향이어서 서리에 의한 피해는 더 커질 수 있다. 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 (1971~2000). 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 20~25 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.

Exploring preventive factors against insufficient antibody positivity rate for Foot-and-Mouth Disease in pig farms in South Korea: a preliminary ecological study

Dongwoon Han,Byeongwoo Ahn,Kyung-Duk Min 대한수의학회 2024 Journal of Veterinary Science Vol.25 No.1

Background: Foot-and-mouth disease (FMD) is a highly contagious viral disease in livestock that has tremendous economic impact nationally. After multiple FMD outbreaks, the South Korean government implemented a vaccination policy for efficient disease control. However, during active surveillance by quarantine authorities, pig farms have reported an insufficient antibody positivity rate to FMD. Objective: In this study, the spatial and temporal trends of insufficiency among pig farms were analyzed, and the effect of the number of government veterinary officers was explored as a potential preventive factor. Methods: Various data were acquired, including national-level surveillance data for antibody insufficiency from the Korea Animal Health Integrated System, the number of veterinary officers, and the number of local pig farms. Temporal and geographical descriptive analyses were conducted to overview spatial and temporal trends. Additionally, logistic regression models were employed to investigate the association between the number of officers per pig farm with antibody insufficiency. Spatial cluster analysis was conducted to detect spatial clusters. Results: The results showed that the incidence of insufficiency tended to decrease in recent years (odds ratio [OR], 0.803; 95% confidence interval [95% CIs], 0.721–0.893), and regions with a higher density of governmental veterinary officers (OR, 0.942; 95% CIs, 0.918–0.965) were associated with a lower incidence. Conclusions: This study implies that previously conducted national interventions would be effective, and the quality of government-provided veterinary care could play an important role in addressing the insufficient positivity rate of antibodies.

이성분트렌드매핑 기법을 이용한 우리나라 인구 변화의 시공간적 역동성 시각화

김현미 ( Hyun-mi Kim ),이상일 ( Sang-il Lee ) 한국사진지리학회 2021 한국사진지리학회지 Vol.31 No.3

본 연구의 목적은 인구 변화의 시공간적 역동성을 시각화하는 대안적인 시도를 소개하고, 이를 우리나라 시군구 인구 데이터를 사례로 검토해보는 것이다. 본 연구는 Schroeder(2010)가 제안한 이성분트렌드매핑 기법을 적용하여, 이 새로운 접근법이 1975년부터 2020년까지 우리나라 인구 변화의 시공간적 패턴을 얼마나 효과적으로 시각화할 수 있는지 살펴보았다. 이성분트렌드매핑 기법은 지도 범례 기능을 하는 이성분트렌드매트릭스를 통해 주성분 분석을 이변량 코로플레스 매핑과 결합시킨 기법으로, 다양한 형태의 트렌드를 동시에 효과적으로 하나의 지도로 시각화한다. 연구 결과, 이 대안적 기법이 비선형적인 트렌드의 공간적 패턴을 효과적으로 시각화한다는 점을 확인하였다. 또한 이 기법이 이변량 색채배열을 논리적이고 적절하게 사용함으로써 시공간적 역동성을 직관적으로 해석하기 쉽도록 한다는 점도 확인하였다. 이에 더해 이 기법이 우리나라 인구 변화의 시공간적 역동성을 탐색하는 데 매우 유용하다는 것을 확인하였다. 서울을 둘러싼 수도권과 대도시 중심의 전반적인 인구 변화의 공간적 패턴을 시각화하는 것을 넘어서, 흥미로운 인구 변화의 지역적, 국지적 패턴을 섬세하게 드러내며 기존의 접근법으로는 포착 할 수 없었던 새로운 정보를 시각화하였다. The purpose of this study is to introduce an alternative attempt to visualize the spatio-temporal dynamics of population change and to examine this new approach by using si-gun-gu level population data in Korea. This study applied the Bicomponent Trend Mapping technique proposed by Schroeder (2010) to assess how effectively this new technique can visualize spatio-temporal patterns of population change in Korea from 1975 to 2020. The bicomponent trend mapping technique combines principal component analysis and bivariate choropleth mapping through a bicomponent trend matrix serving as a map legend to simultaneously and effectively depict various types of trends on a single map. As a result of this study, it was found that this alternative technique could effectively demonstrate the spatial patterns of non-linear trends, and that it made it easy to intuitively interpret spatio-temporal dynamics through using logical and suitable bivariate color scheme. In addition, this technique was found to be quite useful for exploring the spatio-temporal dynamics of population change in Korea. Beyond visualizing the spatial patterns of overall trends in the metropolitan area surrounding Seoul, it delicately revealed interesting regional and local patterns of population trend variations and presented new information that could not be well captured by the existing approaches.