A big change today in the appearance of the jetstream weather map. The coloration is much bolder and brighter, isobar lines are much more visible, and individual jetstream pathways are given better continuity through improved shading of different wind velocities, with some reduced velocities being added. This last is very important because showing more of the lower-velocity speeds will result in the paths being considerably wider as well as less broken down into what has been a series of too many separate legs. We will also now gain sight of small, independent jets of the slow type appearing for the first time in some unusual places, for instance the ones on the equator.
I naturally wanted to see if anything had changed with respect to the noteworthy correspondence between jetstream pathways and the configuration of high-altitude air pressure differences. You can see from this map that everything is the same except for a few places where newly visible jets seem to be lacking any regular clues. One thing that remains very clear is that the strongest jetstream winds always tend to occur in places where two of the major pathways have meandered into positions of close proximity, causing their normal wind speeds to be mutually reinforced.
In the work I have been doing air temperature anomalies at the global surface are commonly found to have a close relationship to the density of discrete water vapor streams that exist at high altitudes, where they are constantly in motion and have a relatively short lifetime. The courses followed by these vapor streams, all of which are well-mapped, are greatly affected by the positioning of more powerful jetstream winds that exist at the same altitude. Because of the vapor’s powerful greenhouse effect, alterations due to these encounters have practical consequences for various weather events at the surface below. This especially includes the potential for events in the higher latitudes where overhead jetstreams tend to be the strongest and most concentrated. I think the new mapping details will be quite helpful when analyzing the outcome of encounters between these two uniquely different types of streams.
There was one other news report today that should not be missed by anyone who is deeply interested in the future outlook for climate change. It covers the publication of a new scientific study having updated information about the current status of Earth’s energy imbalance. James Hansen is one of the lead authors of the study, and he has also written a shorter summary of the findings and their implications, which are quite challenging. In order to prevent certain future temperature increases that are due only to effects from heat that has already been stored in the oceans, we would need to reduce the level of CO2 in the atmosphere back to 350ppm, where it was in 1988. By interpretation, simply stopping all growth in greenhouse gas emissions, without reducing what is already in place, would still allow global temperatures to rise to just short of 2.0C above pre-industrial because of the delayed warming effects of oceanic heat gain. Hansen’s report is available at http://www.columbia.edu/~jeh1/mailings/2020/20200907_Sentinel.pdf
Carl