AbstractThis study investigates winter forecasts of the Northern stratosphere and troposphere using seasonal hindcast experiments of the Japan Meteorological Agency. A main focus is placed on the seasonal forecasts of December-January-February (DJF)-mean Northern Annular Mode (NAM) when the forecasts are initialized in late fall. Results demonstrate that the hindcast data have significant skill for both ensemble mean and category forecasts of the NAM but only in the stratosphere. Probability forecasts for DJF Major Stratospheric Sudden Warmings (MSSWs) are also suggested to be significant (higher probabilities for actual MSSW years) near the 90 % confidence level. The forecast skill of the stratospheric NAM changes with the observed phase of the Quasi-Biennial Oscillation (QBO), although the QBO is not simulated but is only included in initial conditions. The skill is higher for the easterly phase characterized by hits of negative NAM states (weaker than normal polar vortex), whereas it is lower for the westerly phase reflecting misses of positive NAM states. It is finally shown that a verification score for category forecasts of the stratospheric and tropospheric NAM tends to co-vary as a whole. The tropospheric forecast skill is significant when the stratosphere has large NAM anomalies in the real world and they are well forecasted. In contrast, the tropospheric forecasts are sometimes poor when the stratospheric forecasts fail to capture observed NAM conditions. It is speculated that stratospheric and tropospheric forecasts could be improved together through the stratosphere-troposphere coupling for such cases, i.e., by successfully forecasting anomalous vortex states in the stratosphere.
Journal of the Atmospheric Sciences – American Meteorological Society
Published: Jan 9, 2018
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.
All for just $49/month
Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.
Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.
It’s easy to organize your research with our built-in tools.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera