raindancewx Posted November 4, 2017 Share Posted November 4, 2017 In baseball, there are different eras, but you get to choose how to interpret what means what, i.e. Ruth's 714 home runs v. Bond's 762 home runs. With ONI, NOAA is currently using running 30-year means to determine anomalies, so almost every 'anomaly' is based on a new base period and it can make comparisons of events confusing in absolute terms, even if it does work well for anomalies. You can see here that the 1950s anomalies were against 1936-1965 means, and recent events are against 1986-2015. http://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_change.shtml It is is fine for accounting for slow warming in Nino 1.2, 3.4, etc, to give a relative sense of anomalies against recent history, but you also get weird hiccups when you have 8 La Ninas or 12 La Ninas in 30 years instead of 10. To make "hard" comparisons with a steady base period, I took the ERSST V.5 data and created anomalies against 1951-2010, which has both PDO eras, and a number of strong, moderate, and weak cold/warm events. This provides another way of looking at the strength of historical El Nino and La Nina events. To give an example of how this changes thinking, October 1978 & 1996 are a near perfect match in Nino 3.4 in raw temperatures / 60 year anomalies. Sure enough, 1996 is pretty similar to how October behaved nationally for high temperatures. A blend of 1996, 2007, 2013 is also a pretty good match for Jun-Aug, Sept, and Oct temperatures in the US overall...and is close by this stable ONI. Anyway, here is Nino 3.4, raw temperatures, and then 60-year ONI anomaly, from this site - http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/detrend.nino34.ascii.txt This method produces similar El Ninos and La Ninas to the NOAA method of changing ONI 30 year base period every five years. I also have re-calculated Nino 1.2 on a 60-year basis to get a ranking of the "Peru" La Nina / El Nino events. https://www.esrl.noaa.gov/psd/data/correlation/nina1.data Link to comment Share on other sites More sharing options...
raindancewx Posted November 5, 2017 Author Share Posted November 5, 2017 This is what I mean by hiccups - the latest 30 year base period is somewhat colder early in the year against 1981-2010, but warmer the rest of the year. Link to comment Share on other sites More sharing options...
AfewUniversesBelowNormal Posted November 5, 2017 Share Posted November 5, 2017 Old events peaked October-November, New events peak December-January. This is a Global index, meaning the same in both Hemisphere's, meaning could be as significant an event as Global Warming. Food for thought. (I once did a research plotting ONI and a Custom subsurface index- using TAO/Triton maps in certain subsurface areas, warm vs cold, evened out so that mathematics between ONI and Subsurface were similar, and I found that when compared to Northern Hemisphere Winter pattern, the subsurface had much more correlating value the classic Enso effects (Gulf of Alaska, SE of Greenland, etc) Link to comment Share on other sites More sharing options...
raindancewx Posted November 5, 2017 Author Share Posted November 5, 2017 I haven't grabbed SST data for the Western Tropical Pacific, but the JAMSTEC uses stable anomalies for the Modoki boxes - and its pretty interesting seeing why the whole West hasn't been cold in a while. Their "Box C" is the best SST indicator of the entire West being cold that I've found, and it hasn't been cold in a while (Box C is weakly correlated with the AMO too). If you take Box A (Central Tropical Pacific), Box B (East Tropical Pacific) and Box C (West Tropical Pacific) and code them warm/cool for each winter, some pretty clear anomalies show up. Makes me think La Nina / Neutral / El Nino may not even be the right way to look at events, since by this system you get two options for three areas, for eight total patterns. US West: Moisture controlled by Eastern Tropical Pacific (Box B), Heat/Cold by Western Pacific (Box C). US East: Heat/Cold by Eastern Pacific (Box B). These are the options when Box C is warm for the US. Keep in mind, the letters indicate whether each box, from West to Central to East is warm or cold. So WWW means all boxes were warm. WWC means West Warm, Central Warm, East Cold. WCW means West Warm, Central Cold, East Warm. Broadly speaking, 2016-17 was a blend of WWW & WCW since it was wet in much of the south, ala WWW, but similar for temps to WCW (cooler NW, hot elsewhere). Box C = Warm is below. Warm West on balance (obviously a few cold winters) Box C = Cold is Cold West. Options are below. Links to images: https://imgur.com/a/t5IMa https://imgur.com/a/1fY7i https://imgur.com/a/UhSsg Link to comment Share on other sites More sharing options...
raindancewx Posted November 8, 2017 Author Share Posted November 8, 2017 Ten strongest La Ninas, using constant temperatures for calculating ONI, seem to be 1933-34, 1942-43, 1954-55, 1955-56, 1970-71, 1973-74, 1988-89, 1998-99, 1999-00, 2007-08. 1975-76 might be stronger/colder than 1933-34, but close call. Link to comment Share on other sites More sharing options...
so_whats_happening Posted November 9, 2017 Share Posted November 9, 2017 Got a clue where to find OLR maps like such for past events? Or would it be best to reconstruct Precip anom maps to get a better understanding? I know this is an ONI thread but figured I would ask real quick Link to comment Share on other sites More sharing options...
raindancewx Posted November 9, 2017 Author Share Posted November 9, 2017 I'm not sure. Precip in the tropics is probably best. The 1950s ONI values are based on 1936-1965 according to NOAA, so there might be ship reports for precipitation in that era? Have never looked. I think its generally accepted that from 1930-1949 1930-31, 1939-40, 1940-41, 1941-42 were El Ninos, and I consider 1945-46 a Modoki El Nino. 1943-44 is kind of a weird neutral, warm Nino 1.2, near normal but cool Nino 3.4. The La Ninas are 1933-34, 1938-39, 1942-43, 1949-50. Near miss La Ninas/cold Neutrals would include 1931-32, 1932-33, 1937-38, 1947-48, 1948-49. The Dustbowl seems at least partly related to the absence of an El Nino for 8+ years, I'd say March 1931 to November 1939. 1935-36 tried to become an El Nino, but ended up only slightly warm of Neutral. Link to comment Share on other sites More sharing options...
raindancewx Posted November 9, 2017 Author Share Posted November 9, 2017 Saw what's happening linked this on another forum - it's all ONI values, 1870-2017, calculated on a monthly basis using a 1951-2000 mean basis. https://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/Data/nino34.long.anom.data Link to comment Share on other sites More sharing options...
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