 Our next speaker will be Eric Maloney from CSU. Yeah, Eric also gave a talk at the colloquium. Thanks for that, Eric. So whenever you're ready. Can you see my screen? Yeah, it's not full screen yet. How about that? Okay, perfect. Okay, awesome. Okay, so thank you very much, Anish and Yudith for the invitation to give a talk here. So what I'm going to be talking about here is the topic of the MJO and climate change. And so I'm going to summarize some of our recent work that tries to get at thinking about not only how the MJO and the tropics is going to change in a future warmer climate, but also teleconnections associated with the MJO. So I don't think I have to introduce the MJO because I think that most people here know what it is. I always like to show this animation from Adrian Matthews, especially as an introductory slide to give a sense for what the MJO is, you know, very nice animation showing its eastward propagation from the Indian Ocean into the western Pacific. And also, as most of you know, the MJO has teleconnections to other parts of the globe. And so it's very important for modulating, you know, various aspects of climate and weather. So one thing that we've been talking about here today is the impact of the MJO on teleconnections to places like the US West Coast and the NAO, as Frederick talked about. But the MJO also has teleconnections to other parts of the tropics as well. So one thing that I might talk about at the half time at the end of this talk is the fact that the MJO, you know, modulates tropical cyclones and that modulation might actually change also in a future warmer climate. So I'm going to be reviewing here a few papers, and I wanted to show the references here before I went on any further just so you have these afterwards. So I'm going to talk about a couple of papers which use CMIT 5 models under RCP 8.5 to talk about future MJO changes in these models. Another thing that I'm going to talk about is whether we can see any changes to the MJO in the reanalysis records. So this is a paper by one of my graduate students with Elizabeth Barnes that looked at various reanalysis products and detected MJO changes in those. And then if I have time, I'll talk about how the e-specific MJO tropical cyclone connection might change in a future warmer climate. So these four papers here just I'll touch on aspects of them in this talk. So first of all, let me set the stage. And so this plot here shows changes in tropical means, specific humidity, and dry static energy profiles at the end of the 21st century in RCP 8.5 forced model simulations. Blue here is the change in the vertical structure of specific humidity at 2100 basically relative to today. And the red here shows the change in dry static energy profile over the warm pool. The first thing that I want to point out here is that the specific humidity profile tends to strengthen in a future warmer climate. So people think that this affects the MJO by increasing the amount of vertical moisture advection that you get per unit MJO heating anomaly. So if you have a heating anomaly associated with the MJO that produces upward motion, if you strengthen the vertical moisture gradient that would be expected to strengthen vertical moisture advection and maintain the MJO. So that's one thing here. The other thing that you see here is that there's actually an increase in the vertical dry static energy profile in a future warmer climate in the tropics. This is associated with a preferential increase in temperature in the upper troposphere relative to the lower troposphere. And this increases the static stability of the tropics under climate change. And if you were at my talk a couple of weeks ago, I talked about the dominant thermodynamic energy scaling of the tropical atmosphere where you have adiabatic cooling on the left side balanced by diabetic heating on the right side. If you reorganize it, you can see that the ratio of vertical motion to precipitation should be approximately proportional to the inverse of static stability. So this would actually predict for MJO timescale disturbances that if the static stability of the tropics goes up, that would actually weaken the MJO circulation per unit MJO precipitation anomaly. So we'll see if that actually bears out in CMIT5 simulations. Okay, so what I'm going to do is look at multimodal mean and variability for actually eight different CMIT5 simulations that have been assessed to produce good MJO in current climate. So I'm going to show first of all a bunch of essentially variance plots showing on the upper left here where MJO precipitation and the historical simulations in the multimodal mean is high. So you can see that over the Indo-Pacific warm pool, you tend to get high MJO precipitation variability. Similarly over the historical period, you see high MJO omega variability over this same region. And then the difference at the end of the 21st century relative to today is shown on the bottom two panels. So one broad thing that you could see here is that across the tropics, MJO precipitation variance generally goes up in the multimodal mean in RCP 8.5. And this is consistent with the very simple argument I told you before about increases in the vertical moisture gradient in the tropics. But then the other interesting thing that you could see here is that generally variance associated with MJO circulation tends to go down in the multimodal mean. So that's also generally consistent with that argument I made before about static stability. So again, this is the multimodal mean and this is the end of the 21st century. One question is when do these sorts of signals actually become detectable and at what point in the future? So I'm going to show that in this particular slide here. So the first thing that I'm going to show here is the change in MJO precipitation amplitude over the warm pool as a function of decades into the future. So you can see here the colors started 2021 to 2040 and then they go to the end of the 21st century in reddish colors. And this plot here is the change in MJO precipitation amplitude. The line in here indicates the multimodal spread across different models. So one thing that I wanted to point out here is that while you can actually see a detectable change in MJO precipitation amplitude at the end of the 21st century that exceeds the multimodal spread, you don't actually see that earlier in the 21st century and the signal is well embedded within the multimodal spread. So MJO precipitation changes at least by this metric are not detectable until the very end of the 21st century. We'd look at similar changes to MJO circulation anomalies and you see something very similar. You cannot see a signal emerging from the multimodal spread until the end of the 21st century and then what it indicates is a decrease in MJO precipitation amplitude once you get to 2081 to 2100. So there's a change actually in the ratio of MJO wind to precipitation that's actually suggested by this plot and we could actually explicitly look at this and so this is the change in the ratio and in this case is actually calculated first within individual models between MJO wind and precipitation and what you could see is that even in the early part of the record 2021 to 2040 there's actually a detectable change in the ratio of MJO wind to precipitation such as wind anomalies go down per unit MJO precipitation change and then this change is very very robust once you get to the end of the 21st century. So one question I guess is well before I before I talk about that let me look at this a little bit more. So I made some arguments before about you know the expectation from increases in tropical static stability that you would actually get this reduction in MJO wind wind amplitude per unit precipitation and that actually bears out. So on the y-axis of this plot shows the percentage change of MJO circulation relative to precipitation and the multimodal mean is the dot and then the spread across different ensemble members of the you know CMIF5 ensemble is shown in brackets and then on the bottom axis here is the change in inverse static stability. So you can see that you know by 2080 to 2100 there's about a 20% decrease in the amplitude of MJO wind anomalies relative to precipitation and this is predicted actually very nicely by the increase in static stability of the tropics that you can see on the x-axis very very good agreement here. Some models get pushed out to 2300 and you know in those models under RCPA 0.5 there's actually huge you know decreases of like 30 to 40% of you know MJO wind amplitude relative to precipitation so some of this gets pretty extreme as you get further out into the future. So now I guess the question is can we actually see any evidence for changes such as this in the observational record and we actually looked at a couple of reanalysis products. My student weighting show looked at this and this is era five, era two and then the 20th century you know era on the right hand side and on the y-axis shows the ratio of omega 400 to precipitation and the percent change here relative to a base period on the x-axis shows the percentage change in inverse static stability and so you could see here that in all of these analyses especially if you look at the end points um yeah I have to close my little window here um you could actually see that from the beginning of the record in this case for era 20c which is 9010 to the end of the record you see both a decrease in the amplitude of the MJO wind to precipitation anomalies and a decrease in the inverse static stability of the models and so what we see in CMIT 5 seems to be showing up at least in some measures in the observational record. Again there's a lot of caveats here we're using reanalysis precipitation to to look at this which you know might be considered suspect but there's you know some evidence that what we see in the climate models is actually showing up observationally. Some of the you know plots here take weird turns like Mara you know takes sort of this you know left hand turn to actually get to the end point here. Mara 2 actually has structural changes to you know diabetic heating that you know hack actually you know also affect you know the results that you actually show here that have to be taken into consideration and I'm be happy to talk with you know that about that with other people afterwards. Okay how much time do I have left Anish? About yeah three minutes. Three minutes or so. Okay so the question is you know do these you know does this weakening of the MJO circulation that we see in CMIT 5 models at least per unit precipitation actually affect the MJO teleconnections and the answer is that it's complicated. I showed this slide in my colloquium talk some models like the NCAR SPC ESM do show a weakening in MJO teleconnections in a future warmer climate and so this is four times CO2 on the bottom current climate on the top one particular phase of the MJO's teleconnection and you could actually see that the teleconnection in North Pacific and over North America is actually weaker in four times CO2 world relative to pre-industrial. We looked at the reasons why in this study and actually did show that it was associated with weakening of the MJO circulation in the tropics and weakening ability for that to force a Rosby wave source that you know caused a teleconnection in middle latitudes but the complication comes in in that the basic state is also changing so while the MJO circulation itself might be changing you also have to think about from the context of teleconnections how that's actually interacting with changes in the basic state and one thing that CMIT 5 and CMIT 6 models show is that the North Pacific jet is likely to extend further east in a future warmer climate and there was this really nice study Joe Adol here 2020 that showed that one of the effects of this extended Eastern Pacific jet is actually to create a stronger impact of MJO teleconnections on California regardless of whether or not the MJO teleconnection might be stronger or weaker or not simply because the teleconnection pattern has shifted further east so that's a lesson that you know when thinking about MJO teleconnections it's not only MJO changes that are important but also basic state changes that are important as well and one last thing that I want to think about here is teleconnections to other parts of the tropics so one thing that the MJO does it affects precipitation over the eastern Pacific warm pool during boreal summer and this shows an example of a composite showing that when precipitation south of Mexico was enhanced with the MJO there's westerly wind anomalies so we looked at this in CMIT 5 models and we actually showed that the teleconnection of the MJO to the eastern Pacific is actually weakened in a future warmer climate and this is partially due to this weakening of the MJO circulation that I talked about before when I was using thermodynamic energy balance arguments and one consequence of this that you know my former postdoc Heaton and I looked at in this paper is impressed right now is that if you weaken MJO teleconnections to eastern Pacific you actually weaken the effect on things like genesis potential anomalies associated with the MJO so this might actually weaken the influence of the MJO on cyclones near the coast of Mexico and this might actually weaken the ability on sub-seasonal timescale to actually predict these phenomena on a future warmer climate a lot of you know work has to be done on this but it's very suggestive okay so just to wrap up in CMIT 5 models we showed reductions in the strength of the MJO circulation relative to precipitation that are detectable as as soon as 2020 to 2040 in CMIT 5 models individual changes in MJO precipitation or wind are not detectable but the combination as far as the ratio is we show that we can detect some of these changes already in reanalysis to the extent that we can actually believe reanalysis precipitation back to 1910 for example you know big caveat there and then the other thing that we showed is that you know there's not a straightforward connection between MJO wind changes and the tropics and teleconnections you really have to think about how basic state changes also mediate the strength of teleconnection so there's a lot of work that needs to be done there in you know future climate model projections to think a little bit more about that so with that thank you very much for listening and I'll wrap up appreciate your time great thanks a lot to think about especially about the future changes so if there are any questions please post it on chat Jaclyn I see you have a question on the chat please unmute yourself and ask thank you so much for the great talk so I do have a comment and a question the comment it's based on I guess the previous talks most of the stocks emphasize the role of getting the models to reproduce what we observe meaning that models are not doing well especially in the tropics because of the precipitation and age interaction biases so that's kind of worrisome and I would like I guess it would be good if you can comment on like to what degree we can trust on these models that are you know like trying to assess the changes in the climate due to global warming and so my specific question goes to like you showed that you see changes in precipitation as precipitation increases but the circulation slows down so I was wondering do we do you see more frequent but weaker mjo events or do you see fewer but strong mjo events how can you how can we explain that change in precipitation and the atmospheric circulation associated with mjo events yeah yeah thank you for your question very good ones so I agree with you that there are many things lacking as far as mjo simulations in climate models in the current climate we tried to mitigate that a little bit you know for example in this particular analysis here we actually did a you know diagnostic analysis of you know climate models in in current climate and only selected the models that produced a reasonable simulation of the mjo and current climate before we looked at them for future projections and so you know while there might still be you know substantial problems in some of these models we we did try to pre-select the ones that you know did better jobs you know versus others and so that's one thing that we did to try to mitigate try to mitigate that and as far as your question about you know the nature of mjo changes other people have done an analysis of you know the mjo in a future warmer climate and have you know found for example that you know in some models you do get you know reductions in mjo variants due to you know less frequent you know events but you know similar strength for example we didn't actually do that analysis for the subset of models we looked at you know so there's eight models here that we actually you know looked at in this multi-model mean analysis and we didn't you know dig into specific you know models as far as something like that but I think it's definitely worth doing you know to get a sense for what is the nature of you know variability change in these models great thanks Jacqueline and thanks again Eric great talk don't see other questions for now in chat or raised hands Eric okay yeah great thank you