Response to Willis Eschenbach’s WUWT Post “How The El Nino Is Changing”
7 hours ago
Bob Tisdale
Does the start date of Willis Eschenbach’s comparison graph, his Figure 5 (my Figure 1 below), in his recent post at WattsUpWithThat titled “How The El Nino Is Changing”, impact the trends toward La Niña conditions? Answer: Yes. A 9-year earlier start date flattens the trends.
INTRODUCTION
Initial Note: The title of Willis’s recent post at WUWT caught my interest, because it was ENSO related. As you may recall, back when I was blogging regularly, for many years, I wrote many dozens of posts that were cross-posted at WUWT about the El Niño Southern Oscillation, and the coupled ocean-atmosphere processes that drive El Niño and La Niña events, and the aftereffects of those events. In Willis’s post, I was hoping to find analyses and documentation of ENSO coupled ocean-atmosphere processes to show how those were changing. But what did I find? A comparison graph of ENSO indices with linear trends and a curious start date.
So, with that in mind, let’s take a look at that comparison graph, Willis’s Figure 5, which I’ve included as my Figure 1, below. His caption for that comparison graph reads,“Figure 5. LOWESS smooths of four El Nino indices, along with their straight-line trends. El Niño conditions are more positive, La Nina conditions are more negative.”
Figure 1
First: When I was blogging regularly, I had been examining, preparing, and posting graphs of ENSO indices for many years so the first thing that stood out to me was the start year, just before the 1980 hashmark. That caught the attention of at least one other person commenting on the post at WUWT, because most ENSO indices include many decades of data prior to 1980. See the comment by Richard M here and my comment here. Willis’s response to those comments about the start year was that he wanted to include the newest ENSO index, the Multivariate ENSO Index (MEI), and that its data began in 1979.
https://wattsupwiththat.com/2022/12/14/response-to-willis-eschenbachs-wuwt-post-how-the-el-nino-is-changing/
