 Hi, I will show you some part of my PhD work that I've done with my advisor, Marcelo Barreiro. Well, we've had the tropics and the extra tropics and they are two way relationship. On one hand, we can have the tropics driving the extra tropics. This is a very well-known phenomenon and the typical example is an iniostalthenosylation. But what happens on the opposite direction? The extra tropics driving the tropics. Is this possible? Well, this is not a well-known study yet, but we have some evidence that this in this happens. First of all, we have polyclinetic studies. For example, here, I show you something from Chang'an Friedman. In here, you can see a three-time series. During the last great ship period, the first one is a proxy from Greenland Temperature. So that's some time series from the extra tropics. And then the second time series is some proxies for hydrological changes in Cariaco Bay in Venezuela. So that's a tropical location. And the third time series are proxies for hydrological changes in China. So that's located in the Asian Moon-Soon region. What you can see with these three-time series is that they are very well correlated. So somehow indicated that information somehow connects the extra tropical region, Greenland, with the other two locations. Also, we have 20th century observations. For example, again, from Chang'an Friedman. Here, two-time series. The first one is the North Atlantic SST anomaly, detrended from June 2, September. And the second one is the Silent Rainfall Anomaly that we have seen a lot this week, showing some multi-decadal variability. And again, you can see the two-time series are very well correlated. Last, we have numerical simulations. There's a lot of work that has been done on this issue. Here, I will show you only two of them. On the left, you have a work from Chang'an Bits. What they do is they increase the ice in the North enemy sphere high latitudes. And what they find is that in that case, they, as you see in the picture there, the tropical precipitation band shifts. That's the ITCC, the Intertropical Conversion Zone. It's, you have moisten in blue and rain in red. So that indicates that the ITCC shifting toward the South, that in that experiment is the warmer enemy sphere. On the right, we can see something done by Kang'etal. What they do is they take aqua-planet simulations. They put an HECM coupled to a Slava ocean model, but in aqua-planet mode. And again, they, in contra-positions to impose in ice, what they impose is an intermospheric radiant, thermal gradient. And what they find is, again, the same conclusion that the ITCC shifts toward the warmer enemy sphere that in their case is also the South enemy sphere. So the same conclusion in all the works, the ITCC always shifts toward the warmer enemy sphere. So which is the objective of this work is to investigate the ITCC response to an extra tropical thermal forcing using realistic boundary surface condition that in contra-position to the aqua-planet simulations. Also, we want to determine the relative roles of the atmosphere, the sea surface temperature that will go on SST, and the land surface temperatures that I will call LST. So our methodology. We are going to perform a model simulations with the ICDP speedy HECM, and we are going to couple it two slab models, one for the ocean and one for land. So just thermodynamic couple. Our surface boundary conditions are realistic. So no aqua-planet in this case. Our simulations are around for 40 years, and we are going to play with different configuration of the models, changing the region of application of the two slab models that we have. So extra tropical forcing, we are going to impose. Which one? Just to give you some motivation, here I put something from Folland et al. This is the global water summer SST pattern associated with the SAEL route starting in the late 70s and 70s. And what you see is negative SSTs in the northern hemisphere and positive SSTs in the southern hemisphere. So that an inter-hemispheric SST gradient. So with this motivation in mind, with our extra tropical forcing, we look something like this. We are going to impose a warming in the northern hemisphere, high latitudes, and a cooling in the southern hemisphere. To make it extra tropical, we are going to put it only forward of 40 degrees. And the global mean is zero. So first experiment. This experiment is the one where the two slab models, for sea and for land, are applied globally. From now on, all my plots are going to look something like this. It will be anomalies with respect to control. That, with that I mean, for each configuration of the model, I have two runs. One is the control run, that is just the model running along. And then I have the forced run. In this forced run, I impose this warming in the northern hemisphere and cooling in the southern hemisphere. And all the plots are going to be anomalies with respect to the control. Also, I'm only going to show annual means. So I'm not showing any seasonal cycle here. So this first plot is near surface air temperature. As you can see, we have positive anomalies in the northern hemisphere and negative anomalies in the south. That means that there is a generalized warming in the northern hemisphere and a generalized cooling in the southern hemisphere. Remember that the imposed forcing was only applied forward of 40 degrees. But here you can see that the signaling temperature penetrates this barrier of 40 degrees and reach to the tropical region. In the extra tropics, we can see the maximum anomalies are here in the northern Atlantic of about 16 degrees. And here in the south, South Pacific and close to Antarctica about minus 16 degrees. So it's quite a huge anomaly. And in the tropical region, we can see there's some signal where being the signal over Africa, the maximum one of about nine or 10 degrees Celsius. So it's also quite a huge anomaly. What happens with precipitation that is the focus of this study. We see that in extra tropics, there's not much signal. And in the tropics, we see a lot of signal. We see a positive band in the northern tropics followed by a negative band in the southern tropics. That's meaning that the ITCC is placing towards the north. That's again, it's placing to the warm enemy sphere. So consistent with many other works other authors did. So until this point, we found again what other authors did with some other models and some other configurations. So the next question will be, are these DCC shifts that we are seeing possible without changes in the tropical SSDs? To answer that, we will perform a new simulation. We will repeat the experiment, but now keeping the tropical SSD fixed. By tropical, I mean 30 degrees south, 30 degrees north. So now results for this experiment. Fixed tropical SSD and I don't touch the slavola model. That's still applied globally. On the left, just for reference, the original experiment where the global slum models were applied and on the right, the new experiment. So fixed tropical SSD. What I see is that, of course, in the tropical oceans, I don't have any anomaly. That's because I imposed, but there can't be any anomaly there. On the extra tropics, I see mostly the same signal. And in tropical land, what I see is that it only remains some warming over Africa. That's still, it's not 10 degrees that it was there, but it's around seven degrees, the maximum amplitude. So there's still a lot of land response in tropical Africa. What happens to precipitation? What we see is that, well, over the Pacific, the ITCC shifts almost vanished. Over the Atlantic Ocean, we still have something but small. This something small is around 20% of the magnitude of the previous experiment. And what we see is that over tropical Africa, we also still have something, this something is about 60% of magnitude. So are these ITCC shifts that we are still seeing over the Atlantic and over Africa possible without changes in the tropical SSD nor changes in the land surface temperature over Africa? To answer that, again, a new experiment. And now we add to the fixed tropical SSD, we add fixed land surface temperature over Africa. So we switch off the land surface temperature changes over Africa and see what happens. So fixed tropical SSD, fixed temperature of the land over Africa. Again, on the left, you see the original experiment with the global slab models and now the new experiment. What we see is that what happens over Africa, now the warming is very weak. Now it passed from 10 degrees of maximum here to about three or four. In precipitation, what we see is that the signal we have in the Atlantic and over Africa completely vanished. So there's no shift in the SSD. So up to this point, the conclusion is that the land surface temperature over Africa is essential to maintain a shift in the SSD when the tropical SSD is not allowed to change. So the next question is, well, how is this connection between the high latitudes and Africa generated? To answer that, well, what we did is we studied the energy balance in the simulations. And what we saw was that the longer radiation effects was the one that dominates. So longer radiation effect can be decomposed into the clear sky effect plus the clouds effects. We analyze the clouds and see only small changes. So our hypothesis is that the clear sky effect is the one dominant. To test that, we performed a new experiment. Now keeping the fixed tropical SSD and turning off the clear sky longer effect on the mobile to see if that was the one causing the response over Africa. So on the left, you have the experiment with just fixed tropical SSDs where we obtain a lot of response over Africa. And on the right, the new experiment that we add to the fixed tropical SSD is turning off of the clear sky long wave effect. And when we see it's over Africa, the warming is not necessarily reduced. So it goes from seven degrees to around three of maximum response. So what we are proposing, the physical mechanism we are proposing of this teleconnection from the high latitudes to the temperature of the land in Africa is that first the forcing is imposed in the high latitudes that generates a warming there, which produce an increase in the humidity, a specific humidity. Then some of the various relation changes affect the success of humidity to Africa, making the clear sky long wave radiation effect to increase there and then warming the surface there. So all this was done with a slab ocean model. That is a very simple model just a thermodynamic coupling. Now we ask, well, what will happen if we use a more complex ocean model in the tropics? Does the SSD still shift or we don't see anything or is the signal stronger, is the signal weaker? What happens? So we are going to repeat the original experiment but now coupling in the tropical band some ocean dynamics. Which model are we going to couple there? We are going to use a reduced gravity ocean model that's RGO, I will call, that's the same KNCVAC model and just applied in the tropical band, 30 degrees south, 30 degrees north. Again, on the left we have the original experiment for comparison and on the right the new experiment so with this more complex ocean model in the tropics. This is, these are very new results, this is work on progress. What we see is that something we weren't expecting is that in the tropics the signal gets weaker. We were maybe expecting the contrary but no, everything gets weaker, especially in the Pacific Ocean. In the tropics everything is mostly the same, no changes but in the tropics everything gets weaker. What happens in precipitation? Again, everything weaker, much weaker in the Pacific. In the Atlantic and in Africa it's mostly the same but in the Pacific it's really, really much weaker than in the previous experiment. So conclusions, first that the ITC shifts toward the warmening sphere that is in concordance with many other authors' studies. Then when we fix the tropical SST we find that the ITC response weakens a lot but still we have some significant signal over Africa and the Atlantic. When in addition to fixing the tropical SST we fix the land surface over Africa we see that in that case yes the ITC response almost vanishes. So the conclusion of this is the summary is that the ITC response to tropical forcing is not possible just through poorly and unfair processes but needs either the SSTs or neither the land surface temperature over Africa to be generated. And on the last part of the talk about this medium complexity ocean model what we can say this is very preliminary and we don't know why this is happening but what we see is that the tropical ocean dynamics seems to somehow be weakening the response over the Pacific and over the Atlantic Ocean and Africa we have similar signals. Again highlighted and indicated the importance of the land surface temperature over Africa to produce a response there. That's all, thank you.