Interview Meteovigo Judah Cohen, Research Scientist (AER ), Expert Seasonal forecasts

Earlier this Winter Spain and woldwide media in talked about Dr Judah Cohen’s weather predictions. Dr. Cohen is a Massachusetts scientist who had spent several years making North America and Europe winter seasonal predictions with a really high success rate, even up to 75 %. A percentage that clearly exceeds those others from the main and most prominent meteorological centers worldwide.

In Meteovigo we had the pleasure to meet and interview Dr Cohen and now we want to share and disseminate this interview, where a friendly D. Cohen admits that he loves Spain, has already visited us and wish to return on holidays.

We must admit that we were pleasingly surprised to see the love and dedication that Dr.Cohen brigns to his work and above all the humility with he continues working even though right now his company has the highest success rate with significant difference in mid-latitude long term forecasting.

But who is Judah Cohen?

Dr. Cohen joined Atmospheric and Environmental Research in 1998. Prior to AER, he spent two years as a National Research Council Fellow at the NASA Goddard Institute for Space Studies after two years as a research scientist at MIT’s Parsons Laboratory. Cohen received his Ph.D. in Atmospheric Sciences from Columbia University in 1994 and has since focused on conducting numerical experiments with global climate models and advanced statistical techniques to better understand climate variability and to improve climate prediction. Cohen develops AER’s long range forecast products for commercial clients who include some of the largest investment firms in the US. He’s been interviewed on television, the Wall Street Journal, Boston Globe, and Investor’s Business Daily, among others. His work is highlighted by the National Science Foundation (NSF).

Dr. Cohen has a Research Affiliate appointment in the Civil Engineering Department at Massachusetts Institute of Technology (MIT) and is a member of the American Meteorological Society (AMS) and the American Geophysical Union (AGU). He has published over two dozen articles on seasonal forecasting in their journals and others. Most recently, Dr. Cohen was appointed Associate Editor of the Journal of Climate, a peer-reviewed publication of the AMS.

Source Biography: https://www.aer.com/news-events/bios/judah-cohen

Interview

  Have you loved the snow since you were a child, When did you realize you wanted to devote to study the climate?

   As long as I can remember I have loved snow.  In class throughout elementary and even in high school, when it would start to snow I would run to the window to watch.  Of course this did not make me very popular with my teachers.  Also the night before a big snowstorm I could barely sleep from all the excitement. 

In high school for science class I did a report about severe weather.  I really enjoyed researching and writing the report and I also recieved an A+ as my grade.  After that report, I knew that I wanted to study meteorology as long as possible.

  When did you discover the relationship between snow cover in Siberian and winter?

   I was hired as a postdoctoral research scientist at MIT to work with Prof. Dara Entekhabi.  He suggested using a global climate model to study the impact of North American snow cover variability on North American winter weather.  I ran the model with high and low snow cover from different years in the historical record but to be consistent I also changed the Eurasian snow cover. 

The model did produce a very interesting response in the weather but the response was not isolated to North America but was hemispheric in scale and the pattern of variability most closely resembled the North Atlantic or Arctic Oscillation.  This pattern also strongly projects onto the strength of the polar vortex, a term that has been used widely in the media here in the United States the past two years. 

I then found a similar relationship in the observations.  After further modeling experiments and more observational analysis we found that Eurasian snow cover had a bigger impact on winter weather than North American snow cover and that the month when snow cover had the biggest impact on winter weather was October.  During October most of the snowfall that takes place in Eurasia, is over Siberia. 

   What were your expectations for this winter and what is your analysis now over?

   In brief we found that when snow cover is more extensive across Siberia in October, winters are colder in Northern and Eastern Europe, the Eastern United States and East Asia.  Also snowstorms are more likely in these same regions.  And when snow cover is sparse, those same places are milder and snowstorms are less frequent.  This past October, the snow cover across Siberia was the second highest on record.  So we were predicting a cold and snowy winter for the Eastern US but also a cold winter for Europe.  The forecast for the US was fantastic but not so much for Europe. 

(Cohen sent us this selfie that this winter was one of the heavy snowfall.)

   What are the prospects for seasonal forecasting in the future?  

   Seasonal forecasts have not performed well, historically but I think that we can do better.  I think that it is important to look at the entire globe to find predictors or at least hints of what to expect for the upcoming season.  Currently most of the focus in seasonal prediction is the tropics.  It is considered controversial as to whether the Arctic can influence the weather in mid-latitudes.  However I do believe that some of the most important advances in seasonal forecasting in the near future will come from a better understanding of how the Arctic influences the weather in the mid-latitudes.

  Finally, when do we have the pleasure of seeing you here in Spain?

   I would love to come to Spain!  It has been a few years since I have been to Spain.  I have been to Barcelona, which is a beautiful and fun city.  My wife and I dream about a summer beach vacation on the Costa del Sol but so far we have no immediate plans.  But I will keep dreaming.  Also over the years I have interacted with a few Spanish scientists and it would be nice to visit them in Spain.

                                                                                                                                                          More information : https://www.aer.com/

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