Eyes on Earth Episode 80 - ECOSTRESS and Carbon

Hello everyone, and welcome to another episode of Eyes on Earth. Our podcast focuses on our ever changing planet and on the people at EROS and across the globe who use remote sensing to monitor the health of Earth. My name is Jane LaWson, and I'll be hosting today's episode where we're talking about carbon and ECOSTRESS, which stands

for the ecosystems spaceborne thermal radiometer experiment on Space Station. ECOSTRESS collects land surface temperatures in an effort to answer questions about plants use of water. We'll take a look at how these temperature measurements can be useful in characterizing biological influences on the carbon dioxide exchange, specifically in the urban environment of Los Angeles and the non-urban environments

surrounding the city. The NASA Land Processes Distributed Active Archive Center, or LPDAAC for short, is located at EROS and has provided storage and distribution of ECOSTRESS data for 4 years now and counting. Our guests today are here to talk about their work involving ECOSTRESS and carbon.

Nick Parazoo, is a research scientist at NASA's Jet Propulsion Laboratory who studies the interactions between ecosystems and climate through the exchanges of carbon and water. Willow Coleman worked with him at the Jet Propulsion Laboratory as a carbon cycle and ecosystems intern on the Los Angeles study we'll be talking about.

Nick and Willow, welcome to Eyes on Earth! 

PARAZOO:

Thanks for having us. 

COLEMAN:

Thank you so much. 

LAWSON:

First of all, could you each tell us what drew you into this type of research? Nick, do you want to begin? 

PARAZOO:

Yeah, I guess it's a few things.

First I'm a global carbon cycle scientist. So I'm interested in how different urban and non-urban areas are contributing to global carbon dioxide levels. Second, as a terrestrial ecologist, I am interested in how natural and managed landscapes are responding to and affecting carbon and climate.

And third, as an urban resident, who spends a lot of time outdoors when it's cool and less time outdoors when it's hot. I'm interested in how different types of vegetation affect temperature on the ground during the hotter days and potentially reduce the energy costs of staying inside with the AC cranked up.

So naturally, a study on urban ecosystems seemed right up my alley. 

LAWSON:

How about you, Willow? 

COLEMAN:

Yeah. So when I first started my internship with Nick's group, I had really never worked in earth science before, or even climate science.

It was always something I was interested in, but I came into college as a biology major. But once I started on the project, I realized that I really liked working with satellite imagery. I've always been very passionate about photography and maps in general. So being able to spend my days looking at satellite imagery, especially for something that

was supporting a project as important as understanding the urban carbon total cycle was really important to me. And since I've started, it's really been like a very interesting experience to learn all about this new stuff that I had no idea about before I started at JPL.

It was really exciting. 

LAWSON:

This particular study seems pretty complex because you're considering the biological components of an urban landscape and its surrounding area in relation to carbon emissions. So why is this topic important, especially in this particular environment?

PARAZOO:

This topic is important because it affects everyone understanding how urban ecosystems sequester carbon from the atmosphere affects global climate. So for example, more carbon storage by trees in L.A. can affect temperature in Alaska. And sea level around the Pacific Islands.

This topic also affects our ability to track the impact of changes in energy consumption on fossil fuel emissions of carbon in cities. Which affects people such as policymakers in Sacramento and D.C.. And then closer to home, understanding how urban ecosystems affect surface temperature affects our quality of life.

More vegetated parts of the city tend to be cooler than more paved parts of the city. And so the specific question we are after is whether different kinds of vegetation and land use have different impacts on carbon uptake and temperature.

LAWSON:

So what were some of the key takeaways then from your research? 

PARAZOO:

The big general takeaway is that urban plants provide an important negative feedback to climate change in that they cool temperature and store carbon. Probably doesn't seem like much, but it's a big deal for a large built up carbon emitting megacities like Los Angeles. You see a reduction

in surface temperature of several degrees. With slight increases in the fraction of vegetation relative to paved surfaces. And increase in carbon uptake under cooler temperatures. I think the more profound and practical takeaway, though, from a landscaping and urban planning perspective is that the magnitude of these carbon temperature affects very strongly with vegetation type.

The native shrubs like chaparral vegetation are the most productive vegetation type within the city and tend to do especially well during the summer in terms of cooling and carbon uptake due to their deep rooted, summer drought tolerant makeup.

So they're just well adapted for this Mediterranean semi-arid climate that we have in Southern California. And so native shrubs also appear to be as equally productive and as strong of a cooling agent as irrigated vegetation like turf, grass, golf parks and lawns. Which is potentially a big deal for water and energy use.

LAWSON:

And this is applicable then to more than just Los Angeles. You could look at large cities and sort of assume the same thing. 

PARAZOO:

Yeah, this is kind of a test bed. Los Angeles. It's convenient because we live here and we have a lot of great observations. But yeah, our goal is to do this globally at some stage. And you know, we can look at different climates, different cities, different, you know, developing and emerging economies versus more established economies. There's all sorts of questions that we can look at using all this great satellite data that we have.

LAWSON:

Let's talk a little more about the satellite data that helped lead you to these conclusions. How does that translate to practical knowledge on the ground? 

PARAZOO:

I would say that the study would not have been possible without remote sensing.

And I really think Willow should speak to this because she did all the other work with the remote sensing data. But just briefly, we used airborne and satellite imagery to map vegetation at a scale of 60 centimeters, which is about two feet. So that is effectively mapping every plant in Los Angeles.

And so we need this kind of resolution, especially in L.A., which is a very mixed landscape. A lot of paved surfaces is intertwined with parks and golf courses and residential areas. So we used ECOSTRESS to help. Okay,

so we use optical imagery to kind of map out the vegetation. And then ECOSTRESS is to help determine if the vegetation was irrigated or not. Which helped us compare the cooling carbon storage value of irrigated versus non irrigated vegetation.

And Willow came up with this really cool technique using subdaily sampling from ECOSTRESS.

LAWSON:

Willow, would you like to share with us a little more about the remote sensing work that you did on the study? 

COLEMAN:

Yeah, so I think Nick covered a lot of the basics, but to go a little bit more in depth, I

wanted to use remote sensing data in a way that it could be replicated in other cities. Which is something that you mentioned earlier. That was a really important goal of this study, is we didn't want to create something that would just be used in Los Angeles. Eventually

we wanted it to be able to be used in other cities. Carbon issues are not specific to L.A. I ended up using Google Earth Engine. And it makes it really easy to develop these sort of land cover maps without a lot of prior coding experience.

A lot of different earth observation data and satellite imagery is already stored in Google Earth Engine, which makes it really easy to access it. So that was one way that I developed the land cover maps. And then we realized that just having land cover with that 60 centimeter imagery was not quite enough.

We also wanted to learn more about land use. Like how does irrigated versus non irrigated vegetation impact the carbon cycle? So that's where ECOSTRESS data came in. Because we sort of used land surface temperature as a proxy for whether a type of plant was irrigated or not.

But yeah, in terms of you know, being able to replicate this study. I published my code as much as possible online. I developed sort of a website through Google Earth Engine where people were able to interact with the maps and use different layers.

So just creating something that was visually available to the public was something that was really important to me as well. 

LAWSON:

And when you're talking about irrigated areas in Los Angeles. Is it mostly lawns and golf courses? 

COLEMAN:

Yeah, golf courses are actually a really huge source of irrigation in L.A.. Nick, I don't know if you know the exact number, but I know for some cities the majority of residential water usage goes to grass and golf courses. 

LAWSON:

Have either of you used ECOSTRESS data before? 

COLEMEAN:

ECOSTRESS launched when I first started at JPL.

So I never used it before this project. But last year I was a senior at Harvey Mudd College. And my senior thesis project actually focused on using ECOSTRESS land surface imagery. So one of the limitations of ECOSTRESS and using it specifically in urban areas like in the study, is that the 70 meter spatial resolution or

even the 30 meter sharpened resolution that we use in this paper, is often insufficient to detect the heterogeneity of the urban environment. L.A. is really complicated. There's lots of plants right next to buildings, and 30 meters just isn't really enough to to fully understand that complexity.

So to find a potential workaround to this issue, I looked at how a cutting edge machine learning technique called generative adversarial networks or GANS could potentially be leveraged to improve the resolution of ECOSTRESS thermal imagery down to 3 to 5 meters.

So a pretty substantial improvement in resolution. And very broadly, this type of generative adversarial network, it works by relying on spatial resolution from the high resolution, optical satellites and thermal information from ECOSTRESS. So it's sort of combining multiple types of data sources to really improve the resolution of ECOSTRESS imagery quite a bit.

I mean, this is sort of an ongoing project. I got a few preliminary results last year, but definitely there's a lot of a lot of room to improve on existing ECOSTRESS imagery and make it even more usable in urban areas.

LAWSON:

Terrific. Nick, do you have anything to add about ECOSTRESS? 

PARAZOO:

Yeah, we've been trying to use ECOSTRESS for a few years now to study the water use efficiency of plants in different climates. And so water use efficiency tells us about the trade offs that plants have to make between carbon uptake and water loss.

And so high efficiency plants, for example, can take out more carbon molecules or a given water molecule. And so that means they do they do better when it's when it's hot out, hot and dry. And so we can use the ECOSTRESS with other instruments and in particular the other instruments on the International Space Station, such as the orbit

Orbiting Carbon Observatory 3. But it provides a measure of vegetation function and vegetation carbon uptake using this this novel proxy of photosynthesis called solar induced fluorescence. And so when you combine those two instruments and those two measurements together, you can make maps of water use efficiency over time and space. And so we are using ECOSTRESS and OCO 3

together to look at these kinds of trade offs. 

LAWSON:

What do you see as the main values of ECOSTRESS data in this application and in general? 

COLEMAN:

ECOSTRESS can tell you things about land use in urban areas that optical imagery cannot. Such as understanding the difference between irrigated and non irrigated vegetation.

At least in Los Angeles, it might be visually obvious what the difference between irrigated and non irrigated grass looks like from optical satellite imagery. If it's bright green in the summer, it's definitely irrigated because everything else has died.

But would you really be able to tell the difference between an irrigated and a non irrigated tree? So that was one of the reasons why we wanted to look at ECOSTRESS imagery here was to get around the limitations of optical imagery.

PARAZOO:

More generally for urban ecosystem application. The high spatial resolution and some daily sampling has tremendous potential to facilitate urban planning. So if the goal is to save water, ECOSTRESS can tell us which plants are saving the most water under different levels of stress.

And this kind of gets into the water use efficiency application. The goal is to understand how natural ecosystems, either urban or non urban, are coping with drought and heat waves. ECOSTRESS can provide some insight into which ecosystems are resilient and which are vulnerable.

And there are many other applications that fall under this umbrella of water use in plants. Which is an increasingly pressing issue for society. 

LAWSON:

Absolutely. Especially in the West. Willow, you were an intern during this study. So how did it affect your view of research and remote sensing?

COLEMAN:

Interning at JPL was my first big research experience out of college and also my first time working in earth science at all. So I would say that it really strongly shaped my research interests going forwards. I was really lucky to be placed on Nick's research team pretty soon after I got there. Because it was a really exciting

group. An interdisciplinary team of research scientists. But I was also given independence to work on the land cover and land use maps on my own for the next couple of years while still collaborating with all of them. And I also realized that the parts of the earth science research I was doing that I really liked were when I

could also utilize the computer science and data science skills that I gained for my undergrad degree. And after spending some time thinking about this, I realized that like one area in academic research and the government to a little bit is that there's a lot of room for advancement in better software engineering and open source code sharing practices. 

So making sure that the research that we're doing can be repeatable. So I mentioned this a little bit earlier, but I wanted to create a way of developing these land cover and land use maps that could be done in other cities.

And that sort of shaped my career going forwards because I just started this month at Caltech as a Schmidt Academy scholar. And that program is designed especially for bringing the best practices of software engineering into Caltech research groups. Particularly ones who really haven't worked with formal software engineers before.

So I think that's going to be a really important part of research going forward, is how can we better share all of this information and all of this code that we're generating with other people? 

LAWSON:

Congratulations on your new position. It sounds like you have a great future ahead of you. Nick, were you surprised about anything related to your work on this project and did it affect anything in your research afterward going forward? 

PARAZOO:

Yeah, this research was a very different direction for me and it was also a different team.

Everyone kind of we had not worked together before. We had an idea and we share that idea when we wrote the proposal. And then when it got funded, we were excited. And I was amazed how well we work together.

We were we were all very passionate. It was very interdisciplinary. We had, you know, vegetation, ecosystem scientists, atmospheric scientists, carbon cycle, water cycle scientists. And so we all kind of meshed together really well. And I was happy about that.

And I would say our entire team was astounded by the many abilities of Willow. She developed the vegetation and irrigation maps. She didn't mention this, but she published two first authored papers in peer reviewed journals that talked about the development of the land cover and the irrigation map.

And then she was second author on this applications paper looking at urban carbon cycling. And just the leadership that she was able to take on to download these maps and put things on Google Earth Engine and work with the team to develop the software and provide the data to everyone.

It was awesome. And so the study would have been far less interesting without Willow. And certainly not podcast worthy. Looking ahead though, our goal is to apply techniques developed from this research to other cities. And we've talked about this a few times during the podcast.

L.A. was exciting, but we want to do this everywhere eventually. And so it's kind of a proof of concept. And I think the great thing is we've developed a lot of great tools and we have all the right satellites that should make this pretty applicable in other places.

I'm excited to see where this goes. I don't know for sure it's going to get any traction, but, you know, we'll we'll see what happens. 

LAWSON:

Would either of you like to add anything else?

COLEMAN:

Just to you Jane, thank you so much for having us on the podcast. And Nick, thank you for the kind words. I appreciate that this podcast is really bringing light to all of these new important studies on remote sensing.

PARAZOO:

I'd also like to thank you, Jane, for giving this opportunity for us to talk about our research. 

LAWSON:

Well, thank you both, Nick and Willow, for joining us for this episode of Eyes on Earth, where we talked about how ECOSTRESS can contribute to the study of carbon. And thank you to the listeners. Check out our EROS, Facebook and Twitter pages to watch for new episodes. You can also subscribe to us on Apple Podcasts. This podcast is a product of the U.S. Geological Survey/Department of the Interior.