ENSO Blog

In the July 10 update and ENSO discussion, we said the atmospheric part of ENSO doesn’t seem to be responding to the ocean.  El Niño requires that both be in sync and coupled with each other.  Why is the atmosphere acting aloof to the rather warm ocean?  This development may be especially surprising to folks given the rumors and speculation of a very strong El Niño that followed March’s oceanic Kelvin wave. In June, the Bureau of Meteorology in Australia made an interesting observation that might shed light on the lack of coupling between the ocean and atmosphere (1).  They pointed out that an anomalous sea surface temperature (SST) gradient was not in place across the…   Read article

While the focus of this blog is ENSO, there are other important climate patterns that impact the United States during the Northern Hemisphere winter season.  We often focus on the winter season because that is the time of year many climate patterns are most prominent, and in the case of ENSO, this is the season when impacts are most predictable (1). In this post, we will define some of these other patterns and then in a subsequent post in August, we will discuss how much these patterns contribute to U.S. winter climate predictability relative to ENSO.  Long-term Trends A major non-ENSO climate influence, which is particularly important for seasonal temperature, is long-term t…   Read article

Forecasters at the Climate Prediction Center haven’t declared El Niño conditions, even though the Niño3.4 index is currently around 0.5°C above normal, and has been for the past two months. What’s the hold up? In short, we’re waiting for the atmosphere to respond to the warmer sea-surface temperatures, and give us the “SO” part of ENSO. SO what? The Southern Oscillation, that’s what. The Southern Oscillation is a seesaw in surface pressure between a large area surrounding Indonesia and another in the central-to-eastern tropical Pacific; it’s the atmospheric half of El Niño. Since ENSO is a coupled system, meaning the atmosphere and ocean influence each other, both need to meet the criteri…   Read article

When folks hear the term El Niño, they generally think of two things. 1) A decrease in the amount of hurricanes in the Atlantic Ocean and 2) Chris Farley. Ok, they probably only think of #2, but we here at the ENSO blog are trying to broaden that viewpoint. We’ve already discussed US impacts during El Niño but we know it also affects global circulation.   One of ENSO’s most important influences is to the Indian Monsoon—the large-scale circulation pattern that brings the Indian subcontinent the vast majority of its yearly rainfall.  From June through September, India and its population of 1.2 billion receive most of their annual rainfall. To put this into perspective, imagine rec…   Read article

The Signal and the Noise is often mentioned in reference to ENSO forecasting and not just in reference to Nate Silver’s bestselling book.  In fact, understanding what is signal and what is noise is critical to interpreting predictions from models and climate science in general.   Very generally:  (1) Signal:  Signal is the part of the forecast that can be predicted if one were to build a perfect climate model (for example, physical relationships between and within the ocean and atmosphere are perfectly understood and coded into the model).  In seasonal climate prediction, signal can arise from the surface conditions, such as …   Read article