I’ve moved to WordPress. This post can now be found at Animations of Ocean Heat Content, Depth-Averaged Temperature, And Sea Surface Height##############
I created two animations and discovered a third while I was trying to find a way to illustrate a specific process. I haven’t been successful in showing that process, but I’ve elected to post the videos for those who would like different views of other ocean processes, currents, and the like.
UPDATE January 28, 2010: In a later post, Animation Of NODC Ocean Heat Content Data (0-700 Meters) 1955 to 2009, I used the mapping graphics capabilities of the KNMI Climate Explorer to create another OHC animation. I’ve linked it here for convenience. It's much better than the animation of the maps provided by the NODC.
Back To The Original Post
THE ANIMATION OF THE OHC MAPS WAS DISAPPOINTING
Levitus et al provided OHC maps as supplemental material for their 2009 paper “Global Ocean Heat Content 1955–2008 in Light of Recently Revealed Instrumentation Problems”. Link to the paper:
Link to the supplemental material:
Link to the OHC “maps page”:
The animation of the OHC maps wasn’t as noisy as the Sea Surface Height Video from JPL that I used in The Lingering Effects of the 1997/98 El Nino, but the OHC maps illustrated quarterly data, so there were gaps in the data from frame to frame. This can be seen by clicking on the last link above and selecting “Show Animation.” By downloading the maps and creating my own animation I had hoped to be able to prompt something, anything, worthwhile by adjusting the speed. But other than reddish brown blobs moving around on a background of blue, I’ve had no luck. Another problem was the very limited color coding of the maps. The positive OHC is a reddish brown, while the negative OHC is blue. That’s the extent of the color coding. Refer to Figure 1.
As you can see, the gradients of positive and negative OHC are not colored to illustrate intensity. With those limitations, the OHC map animation is not very informative.
Then on the other hand…
THE DEPTH-AVERAGED TEMPERATURE MAP ANIMATION WAS MUCH MORE INFORMATIVE
The European Centre for Medium-Range Weather Forecasts (ECMWF) provides various views of a number of datasets in their S2 Ocean Reanalyses and Real-Time Ocean Analyses web pages. ECMWF Link:
The ocean reanalysis record starts in 1959. It is updated with an 11-day delay. ECMWF Link:
Selecting “Horizontal Maps” and then selecting “Temp averaged in upper 300m” in the drop-down menu under “Field” will bring you to the maps of depth-averaged temperature used in this video. Refer to Figure 2. ECMWF Link:
A sample ECMWF depth-averaged temperature map is shown in Figure 2. Note in the temperature scale to the right that anomalies between -0.5 to +0.5 deg C are not shown. This definitely reduces noise.
When I loaded the individual monthly maps into GIF Movie Gear, the animation flew past, but it showed an incredible number of currents, gyres, oceanic processes, etc. The Pacific Warm Pool makes its presence known, Figure 3, as do the NINO areas in the East Equatorial Pacific.
Easy to identify in the animation are the Kuroshio Extension, the North Atlantic Subpolar Gyre, and the Brazil-Malvinas Confluence. Occasionally, the west to east flow of the Antarctic Circumpolar Current (ACC) is also visible.
Please open the video in a new or separate window for better clarity. You may even wish to expand it to full screen.
And saving the best for last…
THE HIGH-RESOLUTION SEA SURFACE HEIGHT VIDEO
This is not the SSH video I’ve used in past posts:
Recharging The Pacific Warm Pool , and
The Lingering Effects of the 1997/98 El Nino
I discovered this animation on YouTube and contacted the author, Sebastian Krieger, for permission to use it. Sebastian identified the source of the data in his reply: NASA / JPL PO.DAAC. He wrote that he, “regridded it using an auto-correlation based weighted average algorithm.”
Sebastian Krieger’s description of the video on YouTube reads, “15 years of sea surface height anomaly (in mm) from merged TOPEX/Poseidon and Jason-1 datasets ranging from January 1993 to December 2007.“Note the persistent structures like the western boundary currents (Kuroshio, Gulf, Brazil-Malvinas confluence, East-Australian) and the Antarctic Circumpolar Current. Look at the great oceanic gyres. See the discrete seasonal change between the northern and the southern hemispheres. Watch the massive effect of the 1997 El Niño and 1998 La Niña over the surface height. Note especially the westward propagating slow Rossby waves and the faster reflected Kelvin waves, object of my study.
“Finally if you look carefully, notice how the sea surface tends to become more and more red over the years, which means the ocean level is rising.”
At a high resolution, the SSH animation shows the shifting of heat back and forth in the tropical Pacific associated with ENSO events. The Kuroshio Extension, the Gulf Stream, the Agulhas Current and Antarctic Circumpolar Current (ACC), Figure 5, are clearly evident.
The Mozambique and East Madagascar Currents in the western Indian Ocean, Figure 6, are visible, as is a significant eddy where the Agulhas, Benguela, and Antarctic Circumpolar Current meet. The East Australian Current in the western South Pacific can be seen. The Brazil-Malvinas Confluence also stands out.
I had downloaded the video from YouTube with the intent of providing an introduction and some commentary, but the video lost much of the resolution in the conversion. I’ve, therefore, linked the video in its original form. Again, please open the video in a new or separate window for better clarity. You may even wish to expand it to full screen and watch it in high definition. It is so clear one might be able to track how slowly (or quickly) many of the ocean currents and processes transport energy around the globe.
Hopefully, Sebastian Krieger will monitor this post occasionally and answer any of your questions about the video, especially those questions pertaining to Kelvin and Rossby waves.
Post a Comment