Why is spring so cold this year 2018

This west-to-east pressure contrast and the south-easterlies persist in MAM with slightly reduced intensity figures 2 e and 8 b. In addition, a high WTP is partially due to 1 suppressed convection not shown and enhanced downward short-wave radiation in the Philippine Sea figures 8 d and 2 relatively low wind speeds and low latent heat fluxes in the northern part of the Philippine Sea as suggested by Qiao et al figure 8 g , although these effects are not statistically significant.

Figure 8. As a result, barotropic anti-cyclonic circulations are observed on the Korean Peninsula and on the southern part of Japan figures 9 e and f , resembling a Pacific—Japan pattern Nitta , Kosaka and Nakamura , Lee and Lee , Lim and Seo Figure 9. This is most likely because convective activity in the Philippine Sea becomes strong and then SSTs drop in JJA, as the corresponding downward motion in the southern part of East Asia becomes pronounced.

Analogous features are also found in the correlations for the WTP figure 10 b. The results in figures 9 and 10 and table 1 emphasize the substantial role of the WTP in linking winter temperatures to summer temperatures in South Korea. Figure The results in the previous sections emphasize the importance of wintertime atmospheric anomalies on the Eurasia continent to the winter-to-summer links and SWTD variability.

Long-lagged impacts of atmospheric anomalies in the North Atlantic on the Eurasia continent and on tropical Pacific SSTs have been reported by a few studies Wang et al , , Wang , Chen et al b. Therefore, this study examines correlations between the temperature indices, including the SWTD, and various atmospheric indices averaged for DJF.

Table 3. In addition, the positive correlations in the Arctic region and the negative correlations in the mid-latitudes of the North Atlantic and North Pacific resemble a typical spatial pattern of negative AO phases. Table 4. The sign for the SWTD is indicated by color positive in red and negative in blue.

The negative phase composite maps in figure 11 capture the key features associated with the winter-to-summer temperature link e. These features are consistent to the results of the previous studies mentioned above Chen et al , Qiao et al , Myoung Supporting the speculations, all six of the negative composite years correspond to a positive SWTD while six of the seven positive composite years correspond to a negative SWTD table 4.

The out-of-phase temperature link is observed not only in South Korea but also in the neighboring areas in East Asia supplementary figure 3. Possible mechanisms for the winter-to-summer temperature link are summarized in figure When the SWTD is high in a certain year, having a barotropic structure, cyclonic circulations prevail in Europe and East Asia and anti-cyclonic circulations are present in the Arctic regions during DJF, leading to colder winters in South Korea figures 2 a — c.

The increased WTP is mainly due to south-easterlies induced by the west-to-east HGT contrast in the WTP region figures 2 b and 8 a , while the increased NATRI is primarily due to low-level tripole circulation patterns of the atmosphere and associated wind anomalies figures 2 e and f and section 3. The positive values for the WTP index and the NATRI tend to produce anti-cyclonic circulations in JJA and then hotter summers in Korea but with different processes; the former occurs via enhanced downward motion in Korea in response to strong convection over a warm Philippine Sea, resembling Pacific—Japan teleconnection patterns figures 9 and 10 , while the latter is generated by both extratropical Rossby wave propagation from the North Atlantic to East Asia figures 5 — 7 and by tropical connections, i.

Walker circulations between the warm tropical North Atlantic and the cool tropical Pacific, easterlies in the WTP, cyclonic circulations in the northern Indian Ocean, increased precipitation in South Asia, and northward development of anti-cyclonic circulations in Korea, in sequence figures 4 , 6 , and 7.

The tropical connections may enhance the anti-cyclonic circulations in Korea by increasing the WTP in summer and then enhancing Pacific-Japan patterns figure 4 f. This coincides with the finding that zonal wave propagations in Eurasia that are responsible for extreme heat waves in South Korea often accompany meridional wave propagation in the western Pacific Yeo et al The NATRI-related wave propagation in the Eurasia figures 5 and 6 differs from the traditional CGT processes as in the summer of supplementary figures 4 a and b that are guided by the mid-latitude westerly jets; As in Ding and Wang and Kim et al , upper-level anti-cyclones are observed in the northwest of India and in East Asia while lower-level cyclonic circulations inducing precipitation are found in the northwest of India.

This is why the year of is neglected in the analyses in section 3. The strong link since the early s can be attributed to the higher persistency of atmospheric anomalies in winter i.

Although some studies have emphasized the role of higher mid-latitude snow cover associated with Arctic warming and stronger land-atmospheric feedback Zhang et al , Luo and Wang , Chen et al a , more research is required to identify the reasons for the higher persistency of wintertime atmospheric circulation anomalies. Table 5. This suggests that the winter-to-summer temperature link does not arise from forcings related to ENSO variability during the research period of the present study.

The results of the present study suggest that winter atmospheric variability in Eurasia can affect summer temperatures in South Korea by modulating SSTs in the North Atlantic and in the WTP in spring, providing useful information for the prediction of summer temperatures and extreme temperature events in South Korea.

The data that support the findings of this study are available upon reasonable request from the authors. Supplementary data. This site uses cookies. By continuing to use this site you agree to our use of cookies. To find out more, see our Privacy and Cookies policy. Close this notification. Share this article. Article information. Author e-mails. In the second and third ten-day periods of April, and in some cases even over the first ten days of May , western, central, southern and eastern Europe experienced a series of frosty nights, with catastrophic consequences in many places for fruit growing and viticulture.

Losses were so high because vegetation was already well advanced following an exceptionally warm spell of weather in March that continued into the early part of April. For example, the average date of apple flowering in for Germany as a whole was 20 April, seven days earlier than the average for the period to In many parts of Germany, including the Lake Constance fruit-growing region, it even began before 15 April. In the case of cherry trees — whose average flowering date in Germany in was 6 April — it was as much as twelve days earlier than the long-term average.

The frost had a devastating impact because of the early start of the growing season in many parts of Europe. In the second half of April, it affected the sensitive blossoms, the initial fruiting stages and the first frost-susceptible shoots on vines. Spring frost losses and climate change: Trend shows earlier beginning of sweet cherry flowering in Germany. Meteorological conditions. Late frost following a warm spring caused billions in losses in large parts of Europe.

High losses in fruit and wine growing. Two basic concepts for frost insurance. But essentially there are two basic concepts available for frost insurance: indemnity insurance, where hail cover is extended to include frost or other perils yield guarantee insurance covering all natural perils In most countries, the government subsidises insurance premiums, which means that insurance penetration is higher. Late frosts and climate change. There are very clear indications that climate change is bringing forward both the start of the vegetation period and the date of the last spring frost.

Whether the spring frost hazard increases or decreases with climate change depends on which of the two occurs earlier. There is thus a race between these two processes: if the vegetation period in any given region begins increasingly earlier compared with the date of the last spring frost, the hazard will increase over the long term. If the opposite is the case, the hazard diminishes.

Climate change seemingly is bringing forward both the start of the vegetation period and the date of the last spring frost. Further Information Hurricanes cause record losses in - The year in figures. Rain fuels wildfire risk. The hurricane season a cluster of extreme storms. Snow is also expected to fall in parts of interior New England over the weekend, with some residents of Pennsylvania, New Hampshire, northern Vermont and parts of Maine already reporting snowfall.

Skip Navigation. Key Points. Flowers bud on trees as people walk through the snow in an early spring storm on April 2, in New York City. An arctic weather system is expected to hit the northeast US this weekend. VIDEO