• Atmosphere
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• v.26 no.4
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• pp.665-672
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• 2016

In this study, we examine future changes in the Hadley cell (HC) strength using CMIP5 climate change simulations. The current study is an extension of a previous study by Seo et al. that used all 30 available models. Here, we select 18-23 well-performing models based on their significant internal sensitivity of the interannual HC strength variation to the latitudinal temperature gradient variation. The model projections along with simple scaling analysis show that the inter-model variability in the HC strength change is a result of the inter-model spread in the meridional temperature gradient across the subtropics for both DJF and JJA, not by the tropopause height or gross static stability change. The HC strength is expected to weaken significantly during DJF, while little change is expected in the JJA HC strength. Compared to the calculations with all model members, selected model statistics increase the linear correlation between the changes in HC strength and meridional temperature gradient by 13~23%, confirming the robust sensitivity of the HC strength to the meridional temperature gradient. Two scaling equations for the selected models predict changes in HC strength better than all-member predictions. In particular, the prediction improvement in DJF is as high as 30%. The simple scaling relations successfully predict both the ensemble-mean changes and model-to-model variations in the HC strength for both seasons.

• Atmosphere
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• v.21 no.2
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• pp.143-149
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• 2011

A new multi-timescale analysis method, Ensemble Empirical Mode Decomposition (EEMD), is used to diagnose the variation of the MJO activity determined by 850hPa and 200hPa zonal winds from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis data for the 56-yr period from 1950 to 2005. The results show that MJO activity can be decomposed into 9 quasi-periodic oscillations and a trend. With each level of contribution of the quasi-periodic oscillation discussed, the bi-seasonal oscillation, the interannual oscillation and the trend of the MJO activity are the most prominent features. The trend increases almost linearly, so that prior to around 1978 the activity of the MJO is lower than that during the latter part. This may be related to the tropical sea surface temperature(SST). It is speculated that the interdecadal change in the MJO activity appeared in around 1978 is related to the warmer SST in the equatorial warm pool, especially over the Indian Ocean.

• Ocean and Polar Research
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• v.24 no.2
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• pp.147-152
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• 2002

Seasonal and interannual variation of volume transport through the La-Perouse Strait were estimated using the difference of sea level observed at Krillion of Sakhalin, Russia, and Wakkanai of Hokkaido, Japan, during the period of 1975-1988. Historical sea level measurements between Russian and Japanese tide gauge data were normalized using an independent direct volume transport measurement. Volume transport from the East Sea (Sea of Japan) to the Sea of Okhotsk varied from -0.01 to 1.18 Sv with an annual mean value of 0.61 Sv. Monthly water transport rates showed a unimodal distribution with its maximum occurring in summer (August) and minimum in winter (December-February). The annual mean volume transport varied from 0.2 to 0.8 Sv during the period of 1975-1988 with the maximum variance of 0.6 Sv.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.429-436
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• 2017

The seasonal and interannual variations in fish assemblages in the coastal waters off Gijang were examined with an otter trawl from 2015 to 2016. A total of 59 fish species was collected during the study period. The dominant species were Caelorinchus multispinulosus, Clupea pallasii pallasii and Chelidonichthys spinosus. Seasonal changes in fish assemblages appeared to be distinct in the study area. The fish assemblages in summer and autumn were clearly distinguishable from those in other seasons, and the largest numbers of species and individuals were captured in winter and summer, respectively. Because fish assemblages are closely related to changes in water temperature, long-term changes in water temperature can have a significant impact on the productivity of offshore fisheries by changing fish species composition, habitat migration, and growth rate of fish.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2017.11a
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• pp.84-85
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• 2017

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.551-560
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• 2012

The objectives of this study were to elucidate spatio-temporal heterogeneity of water chemistry and develop empirical models using trophic variables in Daechung Reservoir during 2005-2010 along with in situ tests of nutrient enrichment bioassays (NEB). The relations of water quality parameters in regard to precipitation showed that seasonal and interannual fluctuations of biological oxygen demand (BOD), total nitrogen (TN) and pH were minor, whereas conductivity, suspended solids (SS), and total phosphorus (TP) were largely varied in response to the magnitude of rainfall. The CHL maxima occurred immediately after the spate of TP during the high flow, indicating that phytoplankton growth was directly controlled by phosphorus. Empirical linear models of CHL-TP indicated that the variation of CHL in premonsoon was accounted 60% ($R^2$ = 0.60, p < 0.05, n = 54) by TP. In the mean time, empirical models of annual CHL-TN showed that the variation of CHL was weakly accounted ($R^2$ = 0.16, p < 0.001) by TN and more strongly ($R^2$ = 0.44, p < 0.001) by TP. Thus, the variation of CHL was more explained by the variation of TP than TN. In situ tests of Nutrient Enrichment Bioassays (NEBs) showed that the growth of CHL was greater in the P-treatments (as $PO_4-P$) than the control and N-treatment (as $NO_3-P$). Overall, our results suggest that phosphorus was aprimary limiting nutrient controlling the seasonal phytoplankton growth, based on the in situ experiments of NEBs.

• Korean Journal of Environment and Ecology
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• v.29 no.4
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• pp.503-507
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• 2015

To examine the interannual variation of seedfall and seed viability rates of Acer pictum subsp. mono (APSM), we investigated the annual seedfall and seed viability of APSM in the natural broadleaved forest in Mt. Jungwang, Gangwon-do, from 2009 to 2014. The amounts of annual seedfalls from 2009 to 2014 were revealed to be 5,700, 4,060, 60,900, 403,450 and 310 ea/ha respectively. 2013 is presumed to be the masting year since large amounts of seedfall were revealed, compared to that of the other years in the study period. Also, the amount of seeds was significantly different among seed viabilities. Most fallen seeds were damaged or decayed, accounting for 47.88% of the total, followed by empty seeds, undeveloped seeds and sound seeds in that order. The percentage of sound seeds ranged from 6.7 to 31.0%, which marks the lowest average with 16.74%. In the masting year, 2013, a significantly larger number of sound seeds fell at 125,070 ea/ha, on the forest floor than in the other years (320~17,840 ea/ha). Meanwhile, the ratio of damaged or decayed seeds was the lowest at 38%, although the number of those seeds was the largest, 153,310 ea/ha, for the same year. These results imply that the surplus seeds are supplied for natural regeneration in the masting year, supporting the seed predator satiation hypothesis. More long-term researches should be conducted on the seed production of broadleaved trees.

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.519-531
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• 2006

Sea surface height (SSH) around fe Korean Peninsula was investigated as a rising rate of $3.89mm\;yr^{-1}$ on the average from 1993 to 2005, which is 1.3 times higher rising rate, compared to the world ocean. In the present study, to investigate SSH changes in regional sections of the East Sea, the Yellow Sea, the South Sea, and the Korea Strait, DT-MSLA (Delayed Time-Maps of Sea Level Anomalies) with multi-satellite data (Topex/Poseidon, Jason-1, ERS, Envisat), provided by AVISO (Archiving, Validation and Interpretation of Satellite Oceanographic data), was used. The periodicity in interannual variability was dominant for $4\sim5$ year in summer, and 3 year in winter as well as an increasing trend. The amplitude and phase for the annual and semi-annual mode in SSH and SST were investigated with harmonic analysis. The geographical distribution of amplitudes for comparison of SSH and SST are slightly reverse in southwest-northeast tilted direction. The monthly SST and SSH is highly correlated correlation coefficient about 0.7 with lag of one or two months over the East Sea and the South Sea during June-August. These results suggest that the Kuroshio stream is dominant during summer over these regions.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.4
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• pp.235-241
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• 2004

There is a growing concern about the possible increase in inter-annual variation of minimum temperature during the winter season in Korea. This view is strengthened by frequently reported freezing injury to dormant fruit trees, while warmer winters have prevailed recently. The January minimum temperature record at fourteen weather stations was analyzed for 1951-2000. The results showed no evidence of increasing standard deviation at 3 locations between 1951-1980 and 1971-2000, while the remaining 11 stations showed a trend of decreasing standard deviation for the two periods. An empirical model explaining the spatial variation of the standard deviation was derived by regression analysis of 56 stations' data for 1971-2000. Daily minimum temperature and the site elevation may account for 68% of the observed variations. We applied this model to restore the average standard deviation of the January minimum temperature for 1971-2000, and the result was used to produce gridded minimum temperature data for the recurrence interval of 10 and 30 years at 250m resolution. A digital form of the plant hardiness zone map may be developed from this product for site-specific selection of adapted plant species.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.456-461
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• 1999

It is very important for monitoring the interannual variability of sea ice extents in the Okhotsk Sea because the global warming has firstly appeared around the Okhotsk Sea, locating around the southernmost region of sea ice cover in the Northern Hemisphere. In order to develop the sea ice concentration algorithm by microwave sensors onboard satellite, electromagnetic properties of sea ice in the Okhotsk Sea, therefore, were observed by airborne microwave radiometer (AMR), which has the same frequencies as AMSR (Advanced Microwave Scanning Radiometer), ADEOS-II, launching on November, 2000. On this study, it is discussed how to make the image of AMR-EFOV and the video image with nadir angle under flight at the same time, and superimpose the brightness temperature data by AMR-EFOV on the video mosaiced images. For comparing SPOT image, it is clearly that the variation of brightness temperature is small in 89GHz V-pol without the sea ice types and increase at the lower frequency-band.