 OK, next up, please welcome to the stage Joseph LaFredo, coming to us from the University of Albany SUNY. The title of his presentation is a Survey of MPD, Micro-Pulse Dial, Differential Absorption LiDAR Data. Joseph participated in the 2022 Undergraduate Leadership Workshop, which is another program I have the pleasure of getting to run alongside Tim Barnes. He came out for a week as part of a cohort of about 20 students, and we got to bring him back here this year for a full internship experience based in research. Oh, hello. Can you hear me? Is that working? All right, cool. Yeah, thank you, Jerry. And yes, hi, I'm Joseph LaFredo. I got the wonderful opportunity to work with Tammy Weckworth at the Earth Observing Laboratory here at NCAR. Our research focused on doing a survey of MPD, which is a Micro-Pulse Dial, Differential Absorption LiDAR, its data from different field campaigns. Yeah, oh wait, let me make this a little bigger, so I can see. There we go. Yes, so just to give you some background on how this project came about and the motivations for it, over the last 15 to 20 years there have been several calls from the National Research Council to have improved measurements of the thermodynamic profile of the atmospheric boundary layer, the atmospheric boundary layer being the lowest 2 to 3 kilometers of the atmosphere. And there's a number of reasons for why improved thermodynamic profiles would help forecasters, and I'll get into that much later on. But so the MPD was developed by Montana State and the Earth Observing Laboratory. And it's a tool that's still in development to today. And one of the main benefits, I'm not going to get too technical into what the MPD actually how works, but one of the really big benefits to some other existing technologies is that it takes direct measurements, meaning that there's no external calibration required. And that's a really big benefit. And on the right side of the screen, the top right, you can see on the top that's the MPD and the plop below it is a microwave radiometer. And this is measuring water vapor in the atmosphere. And as you can see, the MPD has a really high vertical resolution of water vapor as well as the microwave radiometer is a passive remote sensor. And that goes into what I was just saying about the need for calibration. And so I have the New York State Mesonet logo up there because they use microwave radiometers in their Mesonet. And one of the big challenges that they have is constantly having to calibrate their sensors and them not being very accurate. The MPD is something that might not replace the microwave radiometer, but can be a tool that can greatly enhance forecasts. And again, I'll get into more of how it can help forecasting later on. But yeah, so on the bottom of this, you can see that this is kind of the plot that I'll be showing for the duration of this talk. So I'm going to get you familiar with it. So on the bottom, this is water vapor measured by the MPD. It goes up to about three to four kilometers, at least measuring for the boundary layer. It can go a bit higher than that, but we don't really care about that in most cases. And then on the top is relative backscattering, which can go all the way up to 12 kilometers. So yeah, I'll be showing plots that look a lot similar to this. So just kind of get your bearings with that. Also, this is 50 days worth of data, and there's no downtime on the MPD. So this is also showcasing the potential for a network of MPDs. And this was from the Pecan Field Campaign. And you might be wondering what the Field Campaign is. So it took place in North America, predominantly in Kansas. And on the right side of your screen, you can see that orangey yellow, I don't know what color it is, box, that's the domain of the Field Campaign. I also have pointed out where the MPD actually was located and also where a radar was located. So one of the big advantages of having the MPD out on several different field campaigns is all the different observational tools that were co-located with the MPD. And so I'll get into some cases where different atmospheric phenomena passed overhead of the MPD to just show how useful it can be. So first off, just to give you a little idea of what a gust front is, there's some sort of convection that occurs that has a downdraft. That downdraft has evaporatively cool air that rushes out on all sides, but more so in the direction of where the mean wind is in the atmospheric boundary layer. So here we have a case from July. That shouldn't be July 2nd, it should be June 7th. But here you can see at around 430 UTC a gust front passes overhead of the MPD, and that's illustrated on the S-pole radar at the top right. And as it passes overhead, there is an increase in the water vapor imagery, and that's what you would expect as you have evaporatively cool air rushing out ahead or along that gust front. And additionally, I have a wind profiler that was co-located with the MPD. And you can see an updraft when it passes overhead. That's what you would expect as there's a mesoscale boundary passing through. And then at the end of that loop, you can start to see the gust front actually starts to transition into an atmospheric bore. And you might be wondering what an atmospheric bore is. So an atmospheric bore can originate from a lot of different sources, but for the sake of this talk, you can think of it as just some sort of density current like a gust front shooting out from some sort of convection. And that gust front will and its associated updraft will interact with a buoyancy gradient that exists usually in the form of a stable layer in the atmosphere. And the gust front, which is now turning into a bore, will oscillate along that stability gradient. And you get something like what we see here from, all my days are messed up. That's so weird. No, no, it's not. July 2. So you can see I have the regular MPD image here on the left. And it shows a couple of really interesting things. First off, an elevated moist layer, which is something that we can't really get a lot of profiles for. So this is another kind of advantage of having the MPD. But then on the right, I zoom in to this interesting area where we can see some sort of oscillation or some sort of bouncing around that you can see in the relative back-scattering and also in the water vapor imagery. And looking at some of our observational tools, first this sounding that was taken from about 6 UTC, which is a bit before we actually see that oscillation occur, we can see that we have a stable layer just above the surface, which is an inversion. So that's showing you the potential for an atmospheric bore to exist. And then on the right side of the screen, you can see a radar image where it starts a little bit after the bore has already kind of formed. But as you can see in that radar image, there's no convection visible on the radar, which is just even more evidence that this is a bore because bores can travel and propagate for long periods of time far away from where they may have initiated as a gust front. So yeah, this was a pretty cool case. Next, I'm going to show you a cold front. All you have to really know about a cold front, cold air advancing. There can be upward vertical motion in front of it and downward vertical motion or subsidence behind it. So here's the case. June 28th, around 18 UTC, a cold front passes overhead of the MPD. And we see a drying out of the atmospheric boundary layer. And you can see that also at the top of your screen on the wind profiler, again, co-located with the MPD. It's a little bit difficult to see. And it's actually kind of cool that you can't actually just see only a downdraft after it passes. But there's in the vertical velocity, which is the middle plot, I should explain that. You can see these red and blue kind of streaks up from the ground. And those are associated up and downdrafts. And we call that horizontal convective rolls, which are very common during the development of the convective boundary layer. And so normally after a cold front passes through, you would expect just large-scale subsidence. But because you have daytime heating, you have this turbulence in the boundary layer. And it's not very visible on the MPD. That's just because these horizontal convective rolls weren't condensing out into clouds, so it's not visible on the relative backscattering. But I'll get into more about what a horizontal convective roll is. Yeah, so as I kind of just explained, you have the development of the convective boundary layer after the sun rises. It heats the earth. And the moisture level typically increases, but not always. And you can get this differential heating that occurs that can cause associated up and downdrafts that can lead to cloud streets if it can condense out. And I'm going to show you two days worth of data for this next plot. So I'm also going to show you a mesoscale convective system or an MCS passing overhead of the MPD. What you have to know for an MCS is just that it's a complex of thunderstorms that can propagate for long periods of times. They can shoot out gust fronts. And yeah, let's take a look at it. So yeah, this is a really awesome plot, I think, because it shows off so many different things that the MPD can actually capture. So firstly, in the first couple of hours we see that from about 1 and 1 half kilometers up in the water vapor imagery, it's very dry. And I have four soundings here, starting from 0z and going all the way to 6z. And we can see an elevated mix layer from about, like, 850 kilometer hectopascals. And it's already decaying. And that's evident because the temperature profile, which is in red, is already not dry adiabatic. And the blue, which is the dew point, is already not so much following the mixing ratio. But, and that's evident in the MPD, as around for UTC, we see that the atmospheric boundary layer, starting from about 1 and 1 half kilometers up, starts to moisten up. And then as the day continues to heat up the ground, we see the development of the atmospheric of the convective boundary layer and horizontal convective rules. Unfortunately, there was not a great satellite imagery at this time. So all I have is just a radar image of what horizontal convective rules can look like on the radar. But you can also kind of see it in the relative backscattering and those little blips that pop up from about 16 to 22 UTC before some convection initiates. And then we see a residual layer from about 24 UTC all the way to 30 UTC. That's just that moist layer sticking around overnight. And then around 30, I think, 38 UTC, there's this kind of blank area in the MPD. And that's because there's precipitation and bright clouds the MPD can't see through that. And that's because there's an MCS passing overhead. And you can see that on the top right, that's a mosaic. So it's not just the S-pole. It's a bunch of different radar sites. And that MCS passes overhead. And it quickly decays just right after it passes overhead of the MPD. And so you can see that the atmospheric boundary layer dries out really fast before it tries to kind of rejuvenate itself and moisten back up. But it doesn't have a lot of time. And also there's not a lot of sunlight broken clouds. And so like I said earlier, the MPD is still in development. So this is from Rolopago, which was another field campaign that took place in Argentina in 2018. And at the very lowest part of the water vapor imagery, you can see these spikes of high water vapor and then low water vapor. And that's actually because the air conditioner inside of the MPD was turning on and causing condensation on all the sensors. And so they had never tested the MPD in a really moist environment like Argentina. So this was a good learning experience for them. They since have fixed that issue. And also you can see that the boundary layer really drastically dries out. And I tried looking at some observations to kind of see what was causing that. I came up with that it's probably some sort of downsloping because the MPD was right next to the Sierra de Córdoba. So that's a likely explanation for it, but I'm not 100% sure. And yeah, just some conclusions. The MPD is able to measure water vapor at a really high vertical resolution capturing different atmospheric phenomena. And also on water vapor imagery and relative backscattering. This can greatly help scientists and forecasters better understand the moisture in the boundary layer. Because we still are still learning a lot about moisture in the boundary layer to this very day. There's been a lot of research done with the MPD, like data assimilation into numerical weather models to enhance forecasting and predictability of areas where there is extreme rainfall. And it's been shown to increase accuracy in numerical weather models. And in the future, I hope to not only continue working with TAMI and potentially find more examples and submit them for a BAMS manuscript, but also just continuing working with the MPD as it continues to develop. And they implement temperature profiling and calibrated backscattering into the MPD. And yeah, thank you. Any questions? Do we have any questions from the audience? Daniel? Hi, Jeff. Hi. Great talk. So I know you just mentioned the spikes as a result of the air conditioning. So what were those solutions that they were taking into account? Yeah, that's a great question. Yeah, so I actually got to go see one of the MPDs at EOL. And it's actually kind of funny with the solutions that they came up with. So one of the problems was there's a glass window on the top of the MPD to allow for the radar or the LiDAR beam to shoot through. And so that was condensing up. And so what they did was they actually started blowing like 75 degree air constantly on just that glass to stop it from condensing up. It takes a lot of creativity to kind of solve some of these issues. So that was really, really cool. And yeah, it was really cool learning about it too and just getting to go and see. That was one of the first images that I had here on the left. This is the MPD. And the glass is right there. And there actually, that's the little box that's blowing 75 degree air just constantly onto that glass. So yeah, that was really cool. Thanks for the question. Any other questions? Also, Tammy's amazing. I don't know if I said that. But I love Tammy. She's in Norway. I'm very jealous of that. Hey, Joe. Hello. Great, great talk. Very interesting. And you already kind of said that you came from, I mean, with some background into this topic. But I'm curious if this experience has shifted your research interests, like broadened your horizons in any way. Yeah, that's a really great question. I'm actually really glad that you brought that up. So when I was trying to decide on a mentor to have for this internship, my area of research that I've done and my area of interest is in synoptic meteorology and just large-scale dynamics. So doing something that's really small-scale, almost micro-scale meteorology and working with an instrumentation, that was something that I'd never done before. But I had talked to Tammy and she was just amazing. And I thought that it'd be great to get outside of my comfort zone and work with an amazing scientist like her. So yeah, I think having done this project, I definitely have a greater appreciation for mesoscale meteorology and just working with instrumentation in general. Like as I explained with how they solved an issue with the condensation forming on the glass, it's just all so cool. So yeah, I plan to continue working with Tammy after this internship is done. So yeah, it's definitely changed my interest areas. Yeah, thank you for the question. Any more questions? Also thanks to Ben and Jerry. Oh, question. You guys are awesome as well. I didn't give you guys a shout out. I didn't think I'd have time. This might be a very, first of all, good job. Second of all, this might be a very easy question to answer, but you mentioned at the beginning that the height can be higher, but you don't care? Or you just ignore it? Yeah. What allows you to just ignore those data points? Or why do you just write them? So yeah, that's a good question. That was kind of just me. So we don't actually ignore it or anything. But typically, the MPD can't really see higher than a couple kilometers. And that's mainly because the amount of water vapor in the atmosphere quickly drops off as you go up in height. So really, you're just getting a profile of the thermodynamic atmospheric boundary layer as high as you can. But for instance, anything above three kilometers is really, really low in terms of its magnitude. So you don't really gain much information at all from it. So you're not really ignoring it, but yeah. That was just me, sorry. Great, great talk. Thanks. I was wondering, so the air conditioning, does the instrument itself need air conditioning, or is it? Oh, OK. Yeah, yeah. They need to be able to regulate the temperature inside. And there's a number of reasons for that. But again, one of the main reasons was to prevent problems like what happened, but having tested it in an environment like Boulder, where it was predominantly tested, or like Kansas, they didn't get to be in an environment like Argentina, which is a lot moister. So yeah, thank you. Fantastic work, Joe. Thank you so much.