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- Jeong, Jee-Hoon, 1976, et al.
(author)
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Impact of urban warming on earlier spring flowering in Korea
- 2011
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In: International Journal of Climatology. - : Wiley. - 1097-0088 .- 0899-8418. ; :31, s. 1488-1497
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Journal article (peer-reviewed)abstract
- Using long-term (1954-2004) observations of four selected species in South Korea: goldenbell (Forsythia koreana), azalea (Rhododendron mucronulatum), cherry (Prunus yedoensis), and peach (Prunus persica), the impact of urban warming on spring flowering was investigated. Trends of early spring temperatures and first-flowering dates (FFDs) of the four plants were cross-compared among nine differently urbanized cities. It was clearly observed that urban warming has led to an advance in the timing of first-flowering of several days to weeks during recent decades, while the intrinsic physiology of plants to sense thermal energy has not been changed. The degree of advancement of the FFD was observed to be roughly proportional to degree of urbanization. Moreover, the sensitivity of the FFD to urban warming was estimated to be higher for the shrub species (-9.07 and -6.64 days °C-1 for goldenbell and azalea, respectively) than the tree species (-2.46 and -2.90 days °C-1 for peach and cherry, respectively). Our results suggest that the impact of urban warming should be considered as an influential factor which drives changes in the regional natural environment, especially in regions of rapid urbanization. Copyright © 2010 Royal Meteorological Society
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- JEONG, SJ, et al.
(author)
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Increase in vegetation greenness and decrease in springtime warming over east Asia
- 2009
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In: GEOPHYSICAL RESEARCH LETTERS. - 0094-8276. ; 36
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Journal article (peer-reviewed)abstract
- This study investigates the impact of increased vegetation greening on the springtime temperature over east Asia for 1982-2000. An analysis of station-based temperature records and satellite-measure normalized difference vegetation index (NDVI) indicates that slight warming (<0.4 degrees C 10-yr(-1)) occurred over regions that experienced large increase in NDVI (>= 0.08 10-yr(-1)). On the contrary, strong warming (>= 0.8 degrees C 10-yr(-1)) occurred over regions that exhibited minor changes in NDVI (<0.04 10-yr(-1)). For the most part, this inverse NDVI-temperature relationship observed with the daily maximum temperature. Thus, it is suggested that the decrease in warming was mostly attributable to the increase in evapotranspiration associated with increased vegetation greening. Earlier vegetation growth may have further strengthened the effect of this vegetation-evaporation on spring temperature. Citation: Jeong, S.-J., C.-H. Ho, and J.-H. Jeong (2009), Increase in vegetation greenness and decrease in springtime warming over east Asia, Geophys. Res. Lett., 36, L02710, doi: 10.1029/2008GL036583.
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3. |
- JEONG, SJ, et al.
(author)
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Potential impact of vegetation feedback on European heat waves in a 2 x CO 2 climate: Vegetation impact on European heat waves
- 2010
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In: Climatic Change. - : Springer Science and Business Media LLC. - 0165-0009 .- 1573-1480. ; 99:3-4, s. 625-635
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Journal article (peer-reviewed)abstract
- Inclusion of the effects of vegetation feedback in a global climate change simulation suggests that the vegetation–climate feedback works to alleviate partially the summer surface warming and the associated heat waves over Europe induced by the increase in atmospheric CO2 concentrations. The projected warming of 4°C over most of Europe with static vegetation has been reduced by 1°C as the dynamic vegetation feedback effects are included.. Examination of the simulated surface energy fluxes suggests that additional greening in the presence of vegetation feedback effects enhances evapotranspiration and precipitation, thereby limiting the warming, particularly in the daily maximum temperature. The greening also tends to reduce the frequency and duration of heat waves. Results in this study strongly suggest that the inclusion of vegetation feedback within climate models is a crucial factor for improving the projection of warm season temperatures and heat waves over Europe
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4. |
- JEONG, SJ, et al.
(author)
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Reduction of spring warming over East Asia associated with vegetation feedback
- 2009
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In: GEOPHYSICAL RESEARCH LETTERS. - 0094-8276. ; 36
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Journal article (peer-reviewed)abstract
- Over East Asia, surface air temperature displays a significant increasing trend particularly in early months of the year for the period of 1982-2000. Warming per decade is strongest in late winter, 1.5 degrees C in February and 1.1 degrees C in March, but is significantly reduced in spring, 0.4 degrees C in April and 0.1 degrees C in May. During the analysis period, the reduced temperature increase from late winter to spring is found to be in contrast with the increased vegetation greenness derived from the satellite-measured leaf area index over the domain. We examined this inverse relationship using two climate model experiments-coupled with and without a dynamic vegetation model. In both experiments, strong warming in winter is relatively well reproduced, but weak warming in spring is observed only in the coupled experiment. Analysis of the surface energy budget indicates that weaker spring warming results from an evaporative cooling effect due to the increased vegetation greenness. Over East Asia, the vegetation-evaporation feedback, therefore, may produce seasonal asymmetry in the warming trend. Citation: Jeong, S.-J., C.-H. Ho, K.-Y. Kim, and J.-H. Jeong (2009), Reduction of spring warming over East Asia associated with vegetation feedback, Geophys. Res. Lett., 36, L18705, doi: 10.1029/2009GL039114.
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6. |
- Chen, Deliang, 1961, et al.
(author)
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Recent Recovery of the Siberian High Intensity
- 2011
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In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116
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Journal article (peer-reviewed)abstract
- This study highlights the fast recovery of the wintertime Siberian High intensity (SHI) over the last two decades. The SHI showed a marked weakening trend from the 1970s to 1980s, leading to unprecedented low SHI in the early 1990s according to most observational data sets. This salient declining SHI trend, however, was sharply replaced by a fast recovery over the last two decades. Since the declining SHI trend has been considered as one of the plausible consequences of climate warming, the recent SHI recovery seemingly contradicts the continuous progression of climate warming in the Northern Hemisphere. We suggest that alleviated surface warming and decreased atmospheric stability in the central Siberia region, associated with an increase in Eurasian snow cover, in the recent two decades contributed to this rather unexpected SHI recovery. The prominent SHI change, however, is not reproduced by general circulation model (GCM) simulations used in the IPCC AR4. The GCMs indicate the steady weakening of the SHI for the entire 21st century, which is found to be associated with a decreasing Eurasian snow cover in the simulations. An improvement in predicting the future climate change in regional scale is desirable.
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9. |
- HO, CH, et al.
(author)
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Influence of stratospheric quasi-biennial oscillation on tropical cyclone tracks in the western North Pacific
- 2009
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In: GEOPHYSICAL RESEARCH LETTERS. - 0094-8276. ; 36
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Journal article (peer-reviewed)abstract
- The possible influence of the stratospheric quasi-biennial oscillation (QBO) on tropical cyclone (TC) passages in the western North Pacific (WNP) is examined using TC data recorded by the Tokyo Typhoon Center and the QBO index derived from reanalysis data. The influence is observed to be significant. The number of TCs approaching the East China Sea is large during the westerly phase of the QBO; however, during the easterly phase, the number of TCs approaching the eastern offshore of Japan is large. This difference in the TC tracks is found to be related to the background flow change associated with the QBO. However, the total number of TC events over the WNP and the sum of the number of TCs approaching the aforementioned two regions appear to be unrelated to the QBO phases. Citation: Ho, C.-H., H.- S. Kim, J.- H. Jeong, and S.-W. Son (2009), Influence of stratospheric quasi-biennial oscillation on tropical cyclone tracks in the western North Pacific, Geophys. Res. Lett., 36, L06702, doi:10.1029/2009GL037163.
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10. |
- Jeong, Jee-Hoon, 1976
(author)
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Characteristics of atmospheric circulation associated with cold surge occurrences in East Asia: A case study during 2005/06 winter
- 2008
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In: Advances in Atmospheric Sciences. - 1861-9533. ; 25:5, s. 791-804
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Journal article (peer-reviewed)abstract
- The characteristics of the upper-level circulation and thermodynamical properties for the period when two distinct cold surges broke out over East Asia during the 2005/06 winter are investigated. From early December 2005 to early January 2006, exceptionally cold weather lasted for approximately one month due to two successive cold surges that took place on 2 December 2005 and 2 January 2006, respectively. This study reveals that both involve the upper-tropospheric circulation, which induces the amplification and expansion of the surface Siberian high toward East Asia, but arose from different causes: the former is caused by the upper-level blocking originated from the North Pacific and the latter is caused by the upper-level wave train across the Eurasian Continent. In particular, it is suggested that the lower-tropospheric anomalous wind caused by upper-level circulation anomalies and a steep meridional temperature gradient amplified by phase-locked annual cycle combined to induce very strong cold advection in East Asia, which resulted in exceptionally cold weather that lasted for several weeks. The present results emphasize that the characteristics of the upper-tropospheric circulation can be considered as important precursors to cold surge occurrences in East Asia.
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