• Atmosphere
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• v.20 no.3
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• pp.367-377
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• 2010

Variation of tracer distribution during the vortex-breakup period in the Antarctic region was observed by the data from the Improved Limb Atmospheric Spectrometer (ILAS) and ILAS-II. All four trace species including methane, nitrous oxide, ozone, and water vapor show similar patterns of vertical gradient in spite of different structures of zonal mean mixing ratio. Timings of vortex breakup on each level are estimated by two different methods, and they are compared with zonal standard deviations following the latitude circle of each trace species. Although the tracers have different chemical life times and sink/source, the zonal standard deviation patterns show remarkable similarities. The zonal standard deviation shown here to measure the zonal asymmetry of tracer distribution is believed to diagnose the timing of the Antarctic polar-vortex breakup reasonably well.

• Atmosphere
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• v.26 no.4
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• pp.649-663
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• 2016

This study investigates eddy transports in terms of space and time for momentum, heat, and moisture, emphasizing comparison of the results in three reanalysis data sets including ERA-Interim from the European Center for Medium-range Weather Forecasts (ECMWF), NCEP2 from the National Center for Environmental Prediction and the Department of Energy (NCEP-DOE), and JRA-55 from the Japan Meteorological Agency (JMA) during boreal winter. The magnitudes for eddy transports of momentum in ERA-Interim are represented as the strongest value in comparison of three data sets, which may be mainly come from that both zonal averaged meridional and zonal wind tend to follow the hierarchy of ERA-Interim, NCEP2, and JRA-55. Whereas in relation to heat and moisture eddy transports, those of NCEP2 are the strongest, implying that zonal averaged air temperature (specific humidity) tend to follow the raking of NCEP2, ERA-Interim, and JRA-55 (NCEP2, JRA-55, and ERA-Interim), except that transient eddy transports for heat in ERA-Interim are the strongest involving both meridional wind and air temperature. The stationary and transient eddy transports in the context of space and time correlation, and intensity of standard deviation demonstrate that the correlation (intensity of standard deviation) influence the structure (magnitude) of eddy transports. The similarity between ERA-Interim and NCEP2 (ERA-Interim and JRA-55) of space correlation (time correlation) closely resembles among three data sets. A resemblance among reanalysis data sets of space correlation is larger than that of time correlation.

• Journal of Environmental Science International
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• v.22 no.10
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• pp.1363-1371
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• 2013

In this study, we estimate the interannual spatial and temporal distributions of fishing grounds at night in the East Sea based on satellite and in-situ data. We observe that the $15^{\circ}C$ thermal front moves in the north-south direction according to the movement of the warm water (above $18^{\circ}C$) in the Tsushima Warm Current (TWC) area, forcing the cold water area (below $10^{\circ}C$) to either expand or shrink. The interannual variations of sea surface temperature (SST) in winter represented by the indicator SST of $6^{\circ}C$ are consistent with the east-west zonal areas in the central East Sea which represented over $1^{\circ}C$ standard deviation of SST in February during 1990-2000. Annual SST in the fishing grounds of common squid fishing vessels, observed both by fishing vessels and satellites range from 9-$22^{\circ}C$, with the satellite-observed data having a larger range than the fishing vessel-based ones. The interannual distributions of the common squid fishing grounds in the East Sea are mostly concentrated in the TWC area in the southwestern part of the East Sea and in the coast of southern Honshu and Hokkaido in Japan. The interannual distributions of the nighttime fishing vessels are consistent with the catches investigated from the fishing vessel.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.3
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• pp.120-129
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• 2017

Agrometeorological advisories for farms and orchards are issued when daily weather exceeds a predefined range of the local reference climate, which is a long-term average of daily weather for the location. The reference climate at local scales is prepared by various simplification methods, resulting in uncertainty in the agrometeorological advisories. We restored daily weather data for the 1981-2010 period and analyzed the differences in prediction results of weather risk by comparing with the temporal and spatial simplified normal climate values. For this purpose, we selected the agricultural drought index (ADI) among various disaster related indices because ADI requires many kinds of weather data to calculate it. Ten rural counties within the Seomjin River Basin were selected for this study. The normal value of 'temporal simplification' was calculated by using the daily average value for 30 years (1981-2010). The normal value of 'spatial simplification' is the zonal average of the temporally simplified normal values falling within a standard watershed. For residual moisture index, temporal simplification normal values were overestimated, whereas spatial simplification normal values were underestimated in comparison with non-simplified normal values. The ADI's calculated from January to July 2017 showed a significant deviation in terms of the extent of drought depending on the normal values used. Through this study, we confirmed that the result of weather risk calculation using normal climatic values from 'simplified' methods can affect reliability of the agrometeorological advisories.