weatherwiz Posted September 27, 2011 Share Posted September 27, 2011 Over the past few years the concept of not only classifying ENSO by Nina/Nino/Neutral but the concept of classifying the ENSO phase by west-based/east-based/basin wide has been a fairly hot topic as well as some research done has indicated that where the strongest SSTA anomalies are setup can also have major influences on the downstream pattern. One of the things I have been trying to do is compose a list classifying all Nina's/Nino's as either west/east/basin-wide...only b/c I have never seen anything like this posted. Anyways I know there are several different methods of determining this and I guess there really isn't one definition of doing so. Some methods include taking the anomalies from ENSO region 3 and subtracting that from ENSO region 4....you can also use the TNI index (which can be a major pain b/c the TNI index involves ENSO region 1.2 which can be very volatile) or you can use SSTA reanalysis maps and get a visual sense of where the strongest anomalies are occurring. Anyways I've just been using the Nino 3.4 - Nino 4 method and then using the reanalysis maps as a backup. I've been working on this off and on for over 2 years now so I have composed several lists but some years I'm confused with. I would just like to compose something that is as accurate as possible. I'll just list the Ninas since this upcoming winter will likely be another Nina winter. 1950-1951: west-based 1954-1955: west-based 1955-1956: Started off east-based then shifted more towards west-based by winters end 1956-1957: west-based during the fall shifting more towards east based in winter with a fading Nina 1962-1963: Indecisive 1964-1965: east-based trended towards west-based end of winter 1967-1968: east-based 1970-1971: Basin-wide 1971-1972: East-Bast in fall/early winter with a fading Nina 1973-1974: Basin-wide 1974-1975: Indecisive 1975-1976: east-based 1984-1985: east-based 1988-1989: basin-wide 1995-1996: Indecisive...Nino 3 - Nino 4 indicates east-based, however, maps show west-based 1998-1999: west-based 1999-2000: Basin-wide 2000-2001: west-based 2007-2008: basin-wide 2010-2011: basin-wide Link to comment Share on other sites More sharing options...
skierinvermont Posted September 27, 2011 Share Posted September 27, 2011 Nice work Wiz.. I think I might put something together in excel for this probably developing a formula based on regions 3, 3.4 and 4, which I think might be the best way. Like half the formula 3.4-3 and half 4-3. I'll just import all the data and then I should be able to do it by month and by the season average. Link to comment Share on other sites More sharing options...
weatherwiz Posted September 27, 2011 Author Share Posted September 27, 2011 Nice work Wiz.. I think I might put something together in excel for this probably developing a formula based on regions 3, 3.4 and 4, which I think might be the best way. Like half the formula 3.4-3 and half 4-3. Thanks. I've come across many different types of formulas from PM'ing some people over the past few years but the most common one seemed to be taking the Nino 3 anomaly and subtracting that from the Nino 4 anomaly. Really trying to figure out what the best method is. Looking at the SSTA maps too I feel could actually be a great method b/c you're visually seeing where the strongest anomalies are occurring. For example, like the 1995-1996 Nina...the Nino 3-4 method gives you negative numbers...indicating east-based, however, if you look at the SSTA map that would seem to indicate a more west-based Nina. Link to comment Share on other sites More sharing options...
skierinvermont Posted October 4, 2011 Share Posted October 4, 2011 Thanks. I've come across many different types of formulas from PM'ing some people over the past few years but the most common one seemed to be taking the Nino 3 anomaly and subtracting that from the Nino 4 anomaly. Really trying to figure out what the best method is. Looking at the SSTA maps too I feel could actually be a great method b/c you're visually seeing where the strongest anomalies are occurring. For example, like the 1995-1996 Nina...the Nino 3-4 method gives you negative numbers...indicating east-based, however, if you look at the SSTA map that would seem to indicate a more west-based Nina. I think the reason 1995-1996 comes in as east based nina in the formula is that the western part of region 4 is really warm (actually above average). Check out how far west region 4 extends. It's also not particularly east based even if you use the formula if you consider region 4 is usually not as cold as region 3. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 4, 2011 Author Share Posted October 4, 2011 I think the reason 1995-1996 comes in as east based nina in the formula is that the western part of region 4 is really warm (actually above average). Check out how far west region 4 extends. It's also not particularly east based even if you use the formula if you consider region 4 is usually not as cold as region 3. I see what you mean...that makes total sense. Link to comment Share on other sites More sharing options...
skierinvermont Posted October 5, 2011 Share Posted October 5, 2011 I see what you mean...that makes total sense. It's like you said though.. maybe a qualitative analysis is better.. what's more important: the fact that the center and eastern part of region 4 was very cold, or the fact that western region 4 was quite warm? Maybe I could say better if I understood the mechanism better. What's probably most important is identifying the extreme cases of east vs west (which should be easier to identify) because if the signal is muddled then it probably doesn't have that big of an impact anyways. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 5, 2011 Author Share Posted October 5, 2011 It's like you said though.. maybe a qualitative analysis is better.. what's more important: the fact that the center and eastern part of region 4 was very cold, or the fact that western region 4 was quite warm? Maybe I could say better if I understood the mechanism better. What's probably most important is identifying the extreme cases of east vs west (which should be easier to identify) because if the signal is muddled then it probably doesn't have that big of an impact anyways. What also makes this difficult is I don't think there really is a "set definition" yet of east vs. west. If the signal is muddled, such at which seems the case in this example perhaps it's just best not to classify it as anything? Or perhaps just label it as "neutral based"? Link to comment Share on other sites More sharing options...
ORH_wxman Posted October 5, 2011 Share Posted October 5, 2011 What also makes this difficult is I don't think there really is a "set definition" yet of east vs. west. If the signal is muddled, such at which seems the case in this example perhaps it's just best not to classify it as anything? Or perhaps just label it as "neutral based"? Generally speaking for ENSO, if the signal is muddled, then the forcing is muddled too and other factors are going to play a larger role anyway. Link to comment Share on other sites More sharing options...
mitchnick Posted October 5, 2011 Share Posted October 5, 2011 I think the reason 1995-1996 comes in as east based nina in the formula is that the western part of region 4 is really warm (actually above average). Check out how far west region 4 extends. It's also not particularly east based even if you use the formula if you consider region 4 is usually not as cold as region 3. this map argues otherwise fwiw Link to comment Share on other sites More sharing options...
weatherwiz Posted October 5, 2011 Author Share Posted October 5, 2011 Generally speaking for ENSO, if the signal is muddled, then the forcing is muddled too and other factors are going to play a larger role anyway. That's true. Is this were factors such as NAO/AO and PNA and such would play an overall larger role? Link to comment Share on other sites More sharing options...
skierinvermont Posted October 6, 2011 Share Posted October 6, 2011 this map argues otherwise fwiw No it doesn't.. that's why I specifically said go look at how far west region 4 extends. It extends all the way to the longitude of the Solomon islands off the coast of Papua New Guinea. The numbers don't lie.. region 4 was warmer than region 3 that year and it's because of the warmth in western region 4. The coldest waters were in eastern region 4 but they were offset. Link to comment Share on other sites More sharing options...
weatherwiz Posted October 6, 2011 Author Share Posted October 6, 2011 No it doesn't.. that's why I said go look at how far west region 4 extends. It extends all the way to the longitude of the Solomon islands off the coast of Papua New Guinea. The numbers don't lie.. region 4 was warmer than region 3 that year and it's because of the warmth in western region 4. The coldest waters were in eastern region 4 but they were offset. Correct... December-January-February Nino region anomalies Nino 3: -0.88 -0.91 -0.61 Nino 4: +0.16 +0.27 +0.32 Link to comment Share on other sites More sharing options...
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