The relationship between atmospheric blocking and temperature anomalies in Turkey between 1977 and 2016


Efe B. , Sezen I., Lupo A. R. , Deniz A.

INTERNATIONAL JOURNAL OF CLIMATOLOGY, vol.40, no.2, pp.1022-1037, 2020 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 40 Issue: 2
  • Publication Date: 2020
  • Doi Number: 10.1002/joc.6253
  • Title of Journal : INTERNATIONAL JOURNAL OF CLIMATOLOGY
  • Page Numbers: pp.1022-1037

Abstract

The relationship between the character of atmospheric blocking and surface temperature has not been studied in depth for Turkey. Here, these relationships are investigated for the period 1977-2016. The seasonal mean temperature anomalies for all stations during blocked days varies between -2.1 and 0.8 degrees C. There are four main patterns representing the mean seasonal temperature anomalies for all stations during blocked and non-blocked days. The annual cycle for each group is nearly opposite, and this indicates the impact of blocking on observed temperature, as blocked days comprised 30% of the study period. When focusing on the spatial distribution of mean seasonal anomalies, the winter and fall seasons show that, almost all stations have negative temperature anomalies although anomalies are close to zero during warm seasons (spring and summer). The composite analysis shows that the western part of the country is strongly affected by cold air advection during upstream blocking events and the eastern part of the country is affected by warm temperature advection for downstream blocking events. There is a statistically significant (95% confidence level) negative correlation between blocking intensity and temperature anomalies in all seasons except spring. There is no relationship between both blocking duration and longitudinal extent and the seasonal mean temperature anomaly except during winter, which has a significant negative correlation. The temperature anomaly distribution stratified by season shows that strong positive anomalies are rarely observed in all seasons. Only winter and spring were associated with very strong positive anomalies and only at a few stations. Rex-type atmospheric blocking events are observed during the period of not only the maximum temperature anomaly but also for minimum anomalies. However, the location of the blocking event differed from the typical situation above, with the cold and warm events being located downstream and upstream of Turkey, respectively.