Climatic features of the 2020/2021 winter season and the air temperature and precipitation outlook for the summer of 2021 over Northern Eurasia

2021 ◽  
Vol 2 ◽  
pp. 6-19
Author(s):  
V.M. Khan ◽  
◽  
R.M. Vilfand ◽  
E.V. Emelina ◽  
E.S. Kaverina ◽  
...  

Climatic features of the 2020/2021 winter season and the air temperature and precipitation outlook for the summer of 2021 over Northern Eurasia / Khan V.M., Vilfand R.M., Emelina E.V., Kaverina E.S., Kulikova I.A., Sumerova K.A., Tischenko V.A. // Hydrometeorological Research and Forecasting, 2021, no. 2 (380), pp. 6-19. The main features of the Northern Hemisphere large-scale atmospheric circulation are analyzed for the past 2020/2021 winter. The accuracy of consensus forecasts of air temperature and precipitation compiled during the work of the 19th session of the North Eurasian Climate Outlook Forum (NEACOF-19) is presented, with the skill scores of consensus forecasts for Northern Eurasia. The main features of the thermal state of the ocean and large-scale atmospheric circulation for the coming summer of 2021 are considered and analyzed. A forecast of surface air temperature and precipitation anomalies for the summer of 2021 agreed with the NEACOF-20 experts is formulated. Keywords: North Eurasian Climate Outlook Forum, North Eurasian Climate Center, consensus forecast, air temperature, precipitation, large-scale atmospheric circulation, hydrodynamic models, sea surface temperature

Author(s):  
R.M. Vilfand ◽  
◽  
K.A. Sumerova , ◽  
V.A. Tishchenko ◽  
V.M. Khan ◽  
...  

The main results of the analysis of the Northern Hemisphere large-scale atmospheric circulation features are presented for the 2020 summer. Skill scores of the consensus forecast for the 2020 Northern Eurasia summer are discussed in the context of analyzing the large-scale atmospheric circulation. The prognostic potential of the trend component in forecasting seasonal anomalies of air temperature and precipitation is noted. Keywords: air temperature, precipitation, forecast skill, trends, large-scale atmospheric circulation, sea surface temperature, NEACOF, circulation indices, Arctic ice


2021 ◽  
Vol 4 ◽  
pp. 163-176
Author(s):  
V.M. Khan ◽  
◽  

Based on assessments of the meteorological services of the CIS countries, the skill scores of the consensus forecast for the territory of Northern Eurasia for the summer of 2021 are presented. The results of monitoring circulation patterns in the stratosphere and troposphere over the past summer season are discussed. Climate monitoring and seasonal forecasting results for the current situation are presented. A probabilistic consensus forecast for air temperature and precipitation is presented for the upcoming winter season 2021/2022 in Northern Eurasia. Possible consequences of the impact of the expected anomalies of meteorological parameters on the economy sectors and social life are discussed. Keywords: North Eurasian Climate Forum, North Eurasian Climate Center, consensus forecast, air temperature, precipitation, large-scale atmospheric circulation, hydrodynamic models, sea surface temperature, impacts


2017 ◽  
Vol 8 (4) ◽  
pp. 963-976 ◽  
Author(s):  
Jaak Jaagus ◽  
Mait Sepp ◽  
Toomas Tamm ◽  
Arvo Järvet ◽  
Kiira Mõisja

Abstract. Time series of monthly, seasonal and annual mean air temperature, precipitation, snow cover duration and specific runoff of rivers in Estonia are analysed for detecting of trends and regime shifts during 1951–2015. Trend analysis is realised using the Mann–Kendall test and regime shifts are detected with the Rodionov test (sequential t-test analysis of regime shifts). The results from Estonia are related to trends and regime shifts in time series of indices of large-scale atmospheric circulation. Annual mean air temperature has significantly increased at all 12 stations by 0.3–0.4 K decade−1. The warming trend was detected in all seasons but with the higher magnitude in spring and winter. Snow cover duration has decreased in Estonia by 3–4 days decade−1. Changes in precipitation are not clear and uniform due to their very high spatial and temporal variability. The most significant increase in precipitation was observed during the cold half-year, from November to March and also in June. A time series of specific runoff measured at 21 stations had significant seasonal changes during the study period. Winter values have increased by 0.4–0.9 L s−1 km−2 decade−1, while stronger changes are typical for western Estonia and weaker changes for eastern Estonia. At the same time, specific runoff in April and May have notably decreased indicating the shift of the runoff maximum to the earlier time, i.e. from April to March. Air temperature, precipitation, snow cover duration and specific runoff of rivers are highly correlated in winter determined by the large-scale atmospheric circulation. Correlation coefficients between the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) indices reflecting the intensity of westerlies, and the studied variables were 0.5–0.8. The main result of the analysis of regime shifts was the detection of coherent shifts for air temperature, snow cover duration and specific runoff in the late 1980s, mostly since the winter of 1988/1989, which are, in turn, synchronous with the shifts in winter circulation. For example, runoff abruptly increased in January, February and March but decreased in April. Regime shifts in annual specific runoff correspond to the alternation of wet and dry periods. A dry period started in 1964 or 1963, a wet period in 1978 and the next dry period at the beginning of the 21st century.


2021 ◽  
Author(s):  
Shalenys Bedoya-Valestt ◽  
Cesar Azorin-Molina ◽  
José A. Guijarro ◽  
Victor J. Sanchez-Morcillo

<p>Long-term trends of local winds such as sea breezes have been less addressed in climate research, despite their impacts on broad environmental and socioeconomic spheres, such as weather and climate, agriculture and hydrology, wind-power industry, air quality or even human health, among many others. In a warming climate, sea breezes could be affected by changes on air temperature, as these onshore winds are thermally-driven by gradients between the sea-land air, but also by ocean-atmosphere oscillations or changes in large-scale atmospheric circulation. In the last few decades, advances in wind trends studies evidenced a recovery in global wind stilling during the last 10 years, and differences in the sign-magnitude of wind speed trends were found at seasonal-scale, suggesting the hypothetic effect of the reinforcement of local wind circulations in the warm seasons.</p><p>In this study, we analyze for the first time the long-term trends, multidecadal variability and possible drivers of the sea-breeze speeds and gusts in Eastern Iberian Peninsula during the last 58 years (1961-2019), using homogenized wind speed and gusts data from 16 meteorological stations. To identify potential sea breeze episodes, we developed a robust automated method based on alternative criteria. Our results suggest a decoupling between the declining sea-breeze speeds and the strengthening of the maximum gusts for much of the 1961-2019 period at annual, seasonal and monthly scales, but differences based on locations were also found. Because sea breeze changes can be driven by multiple complex factors (i.e. land use changes, land-sea air temperature gradient, complex orography, etc.), the attribution of causes is challenging. To better understand the causes behind the opposite trends between sea-breeze speeds and gusts, we investigate the effect of e.g. the changes in large-scale atmospheric circulation or physical-local factors.</p>


2017 ◽  
Author(s):  
Jaak Jaagus ◽  
Mait Sepp ◽  
Toomas Tamm ◽  
Arvo Järvet ◽  
Kiira Mõisja

Abstract. Time series of monthly, seasonal and annual mean air temperature, precipitation, snow cover duration and specific runoff of rivers in Estonia are analysed for detecting trends and regime shifts during 1951–2015. Trend analysis is performed using the Mann-Kendall test and regime shifts are detected with the Rodionov test (Sequential T-test Analysis of Regime Shifts). The results from Estonia are related to trends and regime shifts in time series of indices of large-scale atmospheric circulation. Annual mean air temperature has significantly increased at 12 observed stations by 0.3–0.4 K per decade. The warming trend was detected in all seasons but with the higher magnitude in spring and winter. Snow cover duration has decreased in Estonia by 3–4 days per decade. Changes in precipitation are not clear and uniform due to their very high spatial and temporal variability. The most significant increase in precipitation was observed during the cold half-year, from November to March. Time series of specific runoff measured at 21 stations has had significant seasonal changes during the study period. Winter values have increased by 0.4–0.9 l/s per km2 per decade while stronger changes are typical for western Estonia and weaker changes for eastern Estonia. At the same time, specific runoff in April and May has notably decreased indicating the shift of the runoff maximum to earlier time, i.e. from April to March. All meteorological and hydrological variables are highly correlated in winter, determined by the large-scale atmospheric circulation. Correlation coefficients between the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) indices reflecting the intensity of westerlies, and the studied variables were 0.5–0.8. The main result of the analysis of regime shifts was the detection of coherent shifts for air temperature, snow cover duration and specific runoff in the late 1980s, mostly since the winter 1988/1989, which are, in turn, synchronous with the shifts in winter circulation. For example, runoff abruptly increased in January, February and March but decreased in April. Regime shifts in the annual specific runoff correspond to the alternation of wet and dry periods. A dry period started since 1964 or 1963, a wet period since 1978 and the next dry period since the beginning of the 21st century.


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