Notes from the Field

Indigenous Experience Shaping NASA Services in the Amazon

September 7th, 2022 by Jake Ramthun
Maria Elena Paredes, Coordinator of the Community Vigilance Committee for the Ashéninka community of Sawawo Hito 40, discusses maps of Upper Amazon during a breakout group (Photo: Reynaldo Vela, USAID)

In a quiet town on the border of Peru and Brazil, indigenous representatives from across the Amazon met with a team of NASA-funded geographers seeking to better understand how climate change is affecting the region–and trying to set an example for how the scientific community works with indigenous peoples.

Puerto Breu, Peru (population: 600-ish) is not the town you might think of for an important work meeting. A holdover of the late 19th Century Amazonian rubber boom, this remote outpost is only accessible by charter flights or by long, winding journeys by river boat. In June 2022, Breu hosted an important summit between SERVIR Amazonia and indigenous communities from across the southwestern Amazon. The event allowed geographers with SERVIR, a joint program of NASA and the U.S. Agency for International Development, an opportunity to listen to members of the communities they study and learn how to better protect the region from climate change and other environmental challenges. 

SERVIR collaborates with leading scientific and conservation organizations in the region, such as Conservación Amazónica (ACCA) and the Upper Amazon Conservancy, which make events like this possible. The program’s mission is to address climate and environmental challenges by helping communities around the world access and learn to use data from NASA’s Earth satellites. Many of its regional projects in Amazonia are designed to aid rainforest conservation and to prioritize the participation and leadership of local communities in the process.

Breu, Peru is only a few miles from the Brazilian border. The town was chosen as a venue for the event to give greater access to indigenous communities on both sides of the border (Photo: Jacob Ramthun, NASA)

“Much of this region is still forested and remote, but the pace of deforestation and other illegal activities has been intensifying in recent years,” said Katie Walker, a Regional Science Associate with the SERVIR Program who helped with the event. She notes that attention on the southwestern Amazon is a relatively recent development. Scientists and conservationists have historically been preoccupied with the southeastern Amazon, where greater proximity to major cities and highways catalyzed land development. 

“In the Brazilian states of Rondonia and Mato Grosso, for example, most of the land area not occupied by indigenous groups has been either deforested and converted to cropland, or has been influenced by these activities,” Walker said. “But now attention is also turning to the southwestern Amazon, where similar patterns are emerging.”

In Peru’s Ucayali Department and the neighboring Brazilian state of Acre, the Upper Amazon is threatened by climate change and demand for luxury hardwoods. Informal roads, or carreteras, built by logging and mining ventures, cut through the jungle and often serve as stepping stones for further deforestation as further human development follows. In the intense equatorial sun, losing tree cover quickly dries out the ground, which can permanently diminish the soil quality and hinder new growth. To protect the world’s climate and help preserve the region’s human and ecological heritage, scientists need in-depth understanding of ecosystem services in the region. Especially for such a historically isolated region, the scientific community needs to consult the best experts it can find: the indigenous communities who live there.

The accelerating loss of forests in the southwestern Amazon creates a major threat to the region’s many indigenous communities, like the Ashéninka, Asháninka, and Yaminahua/Jaminahua. Historically, scientists and conservationists have often prescribed answers to these communities without acknowledging the generations of knowledge these communities have regarding their surroundings. 

Dr. David Salisbury consults with Asháninka, Ashéninka, and Huni Kuin participants during the event (Photo: Reynaldo Vela, USAID)

Dr. David Salisbury, a geographer from the University of Richmond’s Amazon Borderlands Spatial Analysis Team, led the NASA-funded visit to Breu in June to meet with more than 120 indigenous representatives from communities across the Southwest Amazon. The goal of the meeting was to seek community feedback about online tools that use NASA satellite data to monitor forest conditions in the region, but also to draw connections between the observations seen in satellite imagery and the daily observations of people on the ground. 

“This was a historic workshop given that we had 120 Indigenous participants from 13 different ethnicities representing a transboundary area in Brazil and Peru the size of Michigan,” said Salisbury. “Our top goal was to give our Indigenous counterparts, who are local forest and climate experts, the opportunity to see if their lived experience and long-term observations of the forests, humidity, seasonality, and rainfall matched up with forest and climate trends our University of Richmond team was picking up in our satellite imagery analysis. Once the Indigenous participants became experts in our maps, they saw the benefits of our online tools that could show how ecosystem services could change in their homelands across space and time.”

Though Salisbury has almost 20 years of experience working in this part of the Amazon (he smoothly transitions between English, Spanish, and Portuguese mid-sentence), he emphasizes that his experience is relatively little in comparison to the lived experiences of local communities. In a packed one-room schoolhouse, the team spent two days talking with indigenous communities, inviting them to introduce their communities and explain how each is seeing the manifestations of climate change on a local and personal level. 

“The quantity and quality of participation was amazing […] The key was then to take the first day slowly and focus on building community through the sharing of their own expert knowledge of forest and climate,” Salisbury said. “We mapped out how they were connected to each other through culture, watersheds, and landscape as they introduced themselves. Everyone had the opportunity to get to know each other across gender, age, and geography. Once they established their expertise, built a positive learning community, and shared similar concerns for their future, we introduced the science and technology to our receptive and empowered Indigenous collaborators.”

A group of participants discusses maps of the surrounding region (Photo: Jacob Ramthun, NASA)

The event used discussion groups split by ethnic group, age, and gender to better understand how the effects of climate change and deforestation are experienced in different communities and by different demographics. These groups were asked for their opinions about climate change and for their interpretations of maps the team created using data from NASA Earth satellites. 

“The studies they have done will help us a lot to do our monitoring of the community, and to involve more women,” Maria Elena Paredes said. Paredes is an Ashéninka activist and the coordinator of the Community Vigilance Committee for the Sawawo Hito 40 community in Peru, and was a vocal figure in both the women’s discussion groups and in the broader conversations. 

“[The studies] involve more young people so that they learn how to take care of our forest and community,” Paredes said, noting the high representation of young indigenous participants. Her son Luis was a participant in the youth-focused discussion groups. 

The team hopes that feedback from the event will not only help them better tailor their data and tools to the needs of local communities, but also to set a positive example for centering the expertise and experience of indigenous communities in Earth science research. Healthy dialogue between indigenous groups and the scientific community make for conservation efforts that are more effective and socially just.

The lessons learned in Puerto Breu can hopefully improve the efficacy of applied Earth sciences, and more importantly, set a positive example for the scientific community.

Interning at 40,000 Feet: The NASA Student Airborne Research Program Experience

January 20th, 2022 by McKenna Price-Patak, Jacob Schenthal, and Jacob Ramthun

Participants from NASA’s 2020-2021 Student Airborne Research Program pose in the hangar at Armstrong Flight Research Center in southern California. Photo by McKenna Price-Patak.

For students who want to take atmospheric science as literally as possible, it doesn’t get much better than flying in a NASA aircraft.

Each year, the Student Airborne Research Program (SARP) invites a team of rising college seniors to Armstrong Flight Research Center in Southern California to conduct research aboard NASA’s airborne science fleet. Each aircraft is equipped with instruments for land, ocean, and atmospheric research–enabling sample collection and imaging over the Earth’s surface. After operating the instruments in-flight, participants are then able to use the resulting data for their own individual research projects.

…as soon as they recover from the air sickness, of course.

Jacob Schenthal, who graduated from Vanderbilt University in 2021, was drawn to the NASA SARP program for its emphasis on independent, field-based research and multidisciplinary scientific teams. McKenna Price-Patak, a 2021 Tulane University grad, felt it was a rare opportunity for an undergraduate student to be responsible for an entire research project: from data collection to analysis and project development.

“I’ve always had interests in a variety of fields within Earth science, which is why I was excited about the multidisciplinary aspect of SARP,” Price-Patak said.

Both Schenthal and Price-Patak were placed with Dr. Donald Blake, conducting air sampling aboard the aircraft to study atmospheric pollution.

L-R: Jacob Schenthal, Donald Blake, and McKenna Price-Patak. Photo by McKenna Price-Patak.

Dr. Blake is kind of a big deal in the atmospheric science community. An atmospheric chemist at UC Irvine, Blake is half of the eponymous Rowland-Blake Group: the research lab whose other namesake, the late Dr. F. Sherwood Rowland, won a Nobel Prize in chemistry for identifying compounds responsible for Earth’s ozone hole. Today, Blake continues the lab’s work as a leading expert on the impacts of atmospheric chemistry and air pollution on human health, and has conducted NASA-sponsored airborne research for over 30 years.

“Dr. Blake is a phenomenal mentor and really helped me find a newfound interest in air quality research–which intersects directly with climate change and environmental justice: two of my other passions,” Schenthal said. As Price-Patak put it, “Don takes a genuine interest in each member of his group and their success. When my project took a last minute detour and had to be redone days before final presentations, Don sat with me on Zoom for hours a day helping me recover and create a project I was proud of.”

Air pollution visible in the skies above southern California. Photo by Jacob Schenthal.

Both Schenthal and Price-Patak were accepted into the SARP program in 2020. Unable to make the flights that year due to the COVID-19 pandemic, the program had to take a different approach. For the first time in SARP’s history, participants received air quality testing canisters in the mail to remotely collect initial data points.

“Although the program during summer 2020 was remote, it was exciting to take air samples to help measure emission impacts of the COVID-19 lockdowns,” Schenthal said.

“The way the program pivoted to a virtual environment was incredible,” Price-Patak said. “While we would’ve loved to be in person, we still had so much support from our research groups and mentors so we could successfully complete our projects in the short time frame.”

Schenthal’s project, titled Investigating Xylene and Toluene in Disadvantaged Communities Downwind of LAX, blended NASA’s airborne science data within an environmental justice framework. He examined how xylene and toluene–two airborne compounds that damage the nervous system with chronic exposure–are more common in disadvantaged communities near and around Los Angeles International Airport (LAX). Schenthal found that Inglewood, a predominantly Black and low-income community, experienced exposure levels for both compounds at 50 times the background level. Additionally, his project results indicated the compounds acted as tracers, meaning hundreds of other pollutants are also potentially travelling from LAX throughout these communities.

Price-Patak’s project, Dimethyl Sulfide (DMS) in the Imperial Valley and its impact on Sulfate Aerosol Loading, used data collected on SARP flights from 2014 to 2019 to locate sources of inland DMS. DMS is typically released from plankton in the ocean, and can turn into sulfate aerosols which can cause respiratory illness. Her research indicated there may be inland sources of DMS producing up to 10% of the sulfate aerosols in the Imperial Valley, an important agricultural region east of Los Angeles.

Jacob and McKenna collecting air samples aboard Armstrong Flight Research Center’s DC-8 aircraft. Photo by McKenna Price-Patak.

More than a year later, they got their chance to make the flight. In December 2021, fully-vaccinated participants from the 2020 and 2021 teams were finally able to take their projects airborne. Over the course of a week, the team participated in multiple flights over southern California aboard a DC-8 aircraft, taking samples adding to the program’s extensive record of air quality data.

By the end of the program, Price-Patak and Schenthal were able to rack up a combined 27 hours of flight time–and even experienced sitting in the cockpit for low approaches around Long Beach harbor!

According to Price-Patak, the value of the program comes not only from the work itself, but from the opportunity to connect with other early career scientists.

“Through SARP, I developed a new interest in atmospheric chemistry and connected with other students who have gone on to work as consultants with business firms, pursue PhDs, and everything else in between. Not only is the opportunity to conduct research through the program incredible, but the flights are truly a once in a lifetime experience. I would recommend any undergrad student with a STEM background to apply!”

“SARP has been an incredible experience, both personally and professionally. For me, it allowed me to explore my interest in air quality and environmental justice–all while engaging in field research and my independent research project,” Schenthal added.

Now, Schenthal and Price-Patak credit SARP in helping their careers take off–with both program alumni now working with NASA SERVIR at the University of Alabama in Huntsville (UAH).

A collaboration between NASA and USAID, SERVIR works with organizations around the world to design and implement satellite-based services supporting climate adaptation and natural resource management. Schenthal is the Regional Science Associate for SERVIR’s Mekong hub, while Price-Patak is a graduate research assistant for SERVIR-Hindu Kush-Himalaya while enrolled in UAH’s Master’s program in Earth science. And yes–both are still involved in air quality research. The application for SARP 2022 closes January 26th, and can be found here. Don’t hesitate to apply–and be prepared to pack your dramamine!

A NASA DC-8 aircraft sits on the tarmac at Edwards Air Force Base in Edwards, California. Photo by McKenna Price-Patak.

Using Space to Monitor Air Quality at the Surface

December 16th, 2020 by Andrea Nicolau, SERVIR-Mekong Regional Science Associate

On November 23, the Royal Thai Government’s Pollution Control Department (PCD) and SERVIR-Mekong launched the Mekong Air Quality Explorer (AQE) tool at a press event in Bangkok, Thailand. Due to ongoing COVID restrictions, my colleagues from the SERVIR Science Coordination Office (SCO) and I participated in the event remotely. In working with the SERVIR-Mekong hub, I learned that poor air quality in Southeast Asia is a recurring problem that has lingered for over a decade. In contrast to smaller numbers of ground monitoring stations, Earth observations have proven essential to provide consistent and accurate air quality information. Co-developed by SERVIR-Mekong, PCD, and the Geo-Informatics and Space Technology Development Agency (GISTDA), the AQE uses Earth observation inputs in a web-based platform that forecasts and monitors air quality in the Lower Mekong region.

Press event for the launch of the Mekong Air Quality Explorer tool on on November 23, 2020, in Bangkok, Thailand. Credit: SERVIR-Mekong/ADPC

The press event took place at the Ministry of Natural Resources and Environment in Bangkok, and included remarks, a tool demo, and a Q&A session—and I got to watch it all live online. With about 40 participants, the event featured speakers such as: Mr. Athapol Charoenshunsa, PCD Director General and Chairman of the event; Dr. Steven G. Olive, Mission Director of USAID’s Regional Development Mission for Asia (RDMA); Dr. Lawrence Friedl, Director of NASA Earth Science Division’s Applied Science Program (through a pre-recorded video); and Mr. Aslam Perwaiz, Deputy Executive Director of the Asian Disaster Preparedness Center (ADPC). Additionally, GISTDA, the National Research Council of Thailand, the Prime Minister’s Delivery Unit, the Thai Health Promotion Foundation, the Department of Health, and about 20 local media channels and newspapers were at the event. 

Dr. Lawrence Friedl’s video speech. Credit: SERVIR-Mekong/ADPC

Collaboration with Local and Regional Partners

As some background, SERVIR, a joint NASA and USAID program, works with leading regional organizations to help countries worldwide use Earth observations and geospatial technologies to address environmental challenges. Led by the ADPC, SERVIR-Mekong works with organizations in countries across the Lower Mekong, including Thailand. I wasn’t working with the Mekong hub at the time, but in April of 2019, SERVIR-Mekong initiated a collaboration with local authorities to improve air quality monitoring and forecasting. The release event builds on nearly two years of research, trainings, and collaborative development in the area of air quality monitoring and forecasting. As Aekkapol Aekakkararungroj, a Remote Sensing and GIS Specialist from ADPC and my co-worker, stated: “Tackling air pollution needs to be done right now. This requires cooperation from grassroots to policy makers. Earth observation technology from space is one of the most important tools to bridge the gap—to help them better communicate, and collaboratively manage the situation on the ground.” 

Research and Development for Air Quality Monitoring and Forecasting 

I learned a lot about Air Quality monitoring from Dr. Gupta, the lead scientist of the AQE. He told me that in the past two decades, satellite observations of atmospheric aerosols and trace gases have been used to address surface air pollution issues. NASA has invested significant resources in researching and developing data products ready to be used in applications. The products used for the AQE are created through a research and analysis (R&A) project of NASA’s Science of Terra, Aqua and Suomi-NPP program (PI –  Dr. Pawan Gupta). The R&A project focuses on air quality research and data product development for the Indian-Subcontinent, which has been expanded to include Thailand in collaboration with SERVIR. “AQE is an excellent example where NASA’s R&A program collaborated with NASA’s Applied Science program to use science for real-life application,” said Dr. Gupta.

The AQE uses aerosol and meteorological forecasts from NASA’s existing advanced climate model called the Goddard Earth Observing System (GEOS). GEOS assimilates millions of daily Earth observations and provides global forecasts up to 10 days in advance under its forward processing (FP) stream. Forecasts using the GEOS system are experimental and are produced for research purposes only. Therefore, the AQE uses NASA’s global aerosol forecasts informed by satellite observations, real-time ground monitoring data from the PCD, and an advanced machine learning algorithm to provide three hourly air quality forecasts for the next three days. The machine learning algorithm helps calibrate global forecasts with local conditions and provide better accuracy. This all sounds super cool, right?

In addition, AQE has real-time satellite imagery, fire detection, and aerosol retrievals from NASA’s MODIS and VIIRS sensors. These near real-time products can help human forecasters evaluate model forecasted fields for improved decision making on final forecast outputs. AQE also has gridded historical (past two decades) data on aerosols and fires developed under the R&A project (Gupta et al., 2020). The historical datasets can evaluate change over time and help understand the impact of any significant policy changes on emissions in the region.

From left to right: Fire hotspots; natural-color image from VIIRS on the Suomi-NPP satellite showing smoke from fire activity; and forecasted PM2.5 map by Air Quality Explorer. All images show activities on April 20, 2020.

Capacity Building Through Training at Partner Institutions

In addition to app development, the SERVIR-Mekong team has supported training and youth outreach efforts. Dr. Gupta conducted two training sessions on the Remote Sensing of Air Quality: the first for the ADPC in July 2019, and the second in August 2020 for the PCD and GISTDA, in which I had the chance to participate. The latter was supported by NASA Applied Remote Sensing Training and the Committee of Earth Observation Satellites. These trainings built technical capabilities within Thai institutions on satellite remote sensing basics, the use of satellite data for air quality applications, and advantages and limitations of satellite datasets. These trainings were also used to introduce and get feedback on AQE while still under development.

To increase youth engagement in the work, in February of 2020, SERVIR-Mekong, PCD, USAID, and the Department of State’s Young Southeast Asian Leaders Initiative hosted Smogathon Thailand 2020. The event brought together young professionals, students, and technical experts to tackle air pollution using satellite data.

Dr. Pawan Gupta at the Remote Sensing of Air Quality training at ADPC, Bangkok, in July 2019. Credit: SERVIR-Mekong/ADPC

Development of an Online Visualization System – An Air Quality Explorer

The AQE started as a simple visualization tool for historical aerosols and fire data to support a R&A project. Around the same time, SERVIR-Mekong showed an interest in air quality applications in the Lower Mekong region, which motivated the SERVIR team to further develop this visualization tool and include other data sets. The collaboration with PCD allowed us to use their ground monitoring data, which then combined with GEOS reanalysis (MERRA2) to develop machine learning (ML) models. These ML models were evaluated against independent datasets using a 10-fold validation strategy. Finally, an ensemble model is used to calculate surface PM2.5 for the entire region. These ML models were implemented in automatic data processing, which generate three hourly air quality index maps for the next three days following Thai air quality standards. In addition to historical data and forecasting, near real-time satellite data layers from NASA’s Land, Atmosphere Near real-time Capabilities for EO (LANCE) were incorporated in the tool. The AQE had been through testing and improvement for almost a year with all the partners, including PCD, GISTDA, and SERVIR-Mekong, before it was adopted by PCD and became part of the Thai air quality management system.

SERVIR-Mekong Air Quality Explorer. Credit: NASA/USAID/SERVIR-Mekong

Future Work   

The adoption of AQE by the PCD is an excellent example of how NASA’s science, research, and data are being applied around the world to address real-life problems. The AQE is also a first step by PCD in adopting Earth observations to complement and fill gaps in ground-based air quality monitoring systems. The AQE also addresses air quality forecasting, a gap in their air quality management program.

Since the adoption and release, PCD has already made several improvement requests for the AQE tool to serve their air quality needs. This includes improved spatial resolution, expanding the regional coverage to include neighboring countries to understand transboundary pollution, and including data on more air pollutants such as ozone, SO2, and NO2. There is also an opportunity to explore air quality observations by geostationary satellites by JAXA (i.e., Himawari-8/9) and KARI (i.e., GEMS) for the region. SERVIR-Mekong and SCO will continue to work on these aspects in close collaboration with PCD and GISTDA. I’m really excited to contribute to this effort and see the direction the AQE will take in the future!

Local Agencies in Guyana to Monitor Mangroves in Face of a Changing Climate

February 4th, 2020 by Andrea Nicolau, SERVIR-Amazonia, NASA Servir Science Coordination Office

Mangrove forests are some of the most productive ecosystems in the world, sustaining the livelihoods of millions of coastal dwellers. These unique forests sequester carbon, protect coastlines and infrastructure against storm surges, promote fisheries, and are sources of lumber and charcoal. Last week I supported a workshop at the University of Guyana on using Synthetic Aperture Radar (SAR) to monitor these unique ecosystems with my colleague Glenn Hyman from SERVIR-Amazonia and Marc Simard from NASA-JPL (Check out Chapter 6 of the SAR Handbook for the training/tutorials).

When I arrived in Georgetown, the capital of Guyana, I was impressed to learn Guyana’s coast is as much as 2 meters below mean high tide! The country already foresees problems of (intensive flooding and saltwater intrusion) in its lowlands related to sea level rise from climate change. 

This panoramic was taken during high tide on January 23, 2020, along a 280-mile long sea wall–Guyana’s current man-made protection mechanism.. (Credit: Glenn Hyman)

That is why Guyana’s government agencies, NGOs and SERVIR-Amazonia are working to support the generation of an operational monitoring system for mangrove forests. Mangroves can serve as a natural sea wall by building up soils and sediments, protecting the coast. 

This first workshop exposed participants to available satellite imagery, including the Japan Aerospace Exploration Agency’s (JAXA) ALOS PALSAR data, ALOS PALSAR 2 mosaics, and the European Space Agency’s (ESA) Sentinel-1 data; as well as how to use the Alaska Satellite Facility’s (ASF) Vertex to access these datasets. Participants also learned how to pre-process radar data using ESA’s SNAP platform, and how open-source QGIS software and digital elevation models  (SRTM and TanDEM-X) can be used to estimate height and biomass of mangrove forests. Trust me, the look on the participants’ faces after they finalized their first biomass maps was exhilarating. The knowledge gained in this training will enable the use of the most up-to-date information on the state of mangroves along the entire coast in Guyana’s national forest.

The training was led by Dr. Marc Simard of NASA’s Jet Propulsion Laboratory, a senior scientist with a focus on developing products from active remote sensing instruments to study coastal wetlands. Marc’s work includes mapping mangrove canopy height and aboveground carbon stocks globally. (Credit: Glenn Hyman)

From my perspective, the best part of the workshop was going out into the field. On the last day, we visited a nearby mangrove restoration site and moving through the forest was no easy task! At the end of the visit, we were lucky to still have our boots on from our struggle to walk in the deep, sticky mud. The participants were instructed to measure tree height, diameter at breast height (DBH) and establish forest plots using clinometers (a fancy word for an instrument that measures elevation, slope, and depression of an object), laser range finders for measuring the distance to an object, and measuring tapes for recording tree diameter. With this information (known to scientists as validation data) we are able to calibrate the equations we use to model mangrove forests with remote sensing. 

Here we are, all clean, before entering the mangrove restoration site (Credit: https://servir.ciat.cgiar.org)
Reshana Thomas of the Guyana Forestry Commission measures the DBH of a tree (image right) and Devon Wintz from the Department of Environment (image left) fights for his boot. You can see how deep our feet sink into the ground.

I am really looking forward to our continued work with this enthusiastic group of people and to be back in Georgetown for a follow up training in May of this year. We are planning to do a “hackathon” as the second phase to develop the mangrove monitoring system. 

Preliminary map of aboveground biomass by Rehana Thomas of the Ministry of Natural Resources during the workshop (Credit: Rehana Thomas).

Estimating Forest Stand Height in the City of Life

January 31st, 2020 by Helen Blue Baldwin, Regional Science Associate, NASA SERVIR Science Coordination Office

My colleague, Tim Mayer, and I just made it home from leading a three-day workshop focused on estimating forest stand height using L-band Synthetic Aperture Radar (SAR) data. Hosted by the SERVIR-Mekong hub at the Asian Disaster Preparedness Center (ADPC), this activity is part of the SERVIR and SilvaCarbon forest monitoring SAR Handbook initiative, which provides researchers with tools to use SAR for forest monitoring and biomass estimation. 


Located in Thailand’s Chao Phraya river delta, Bangkok is a bustling hub with over eight million residents covering 600 square miles (1,554 square kilometers). The city contains everything from urban shopping malls to mangrove swamps! 

Generally, remote sensing researchers interested in tropical regions have a difficult time finding  satellite imagery with little to no clouds. L-band SAR, with a wavelength of about ~25 cm, penetrates through clouds, providing a unique opportunity to see through forest canopies and enabling measurements of the limbs and trunks of trees from space. Forest height and density reflect the forest age and health. In addition, forest height can be used to estimate Above Ground Biomass (AGB), and the amount of carbon sequestered by vegetation. This is important to organizations like the United Nations REDD+ Programme, which works with partner countries to reduce greenhouse gas emissions from deforestation and degradation. In South and Southeast Asia, the SERVIR-Mekong and SERVIR-Hindu Kush Himalaya hubs support these partners in deriving estimates for forest monitoring and evaluation purposes.


Each morning, I boarded the train and rode two stops to the workshop. Bangkok has grown rapidly and organically, out of necessity. In order to reduce pollution levels, public transportation  has expanded and is an efficient way to move around the city.

The workshop participants came from governmental departments and universities, including the Ministry of Environment (Cambodia); Forest Inventory & Planning Institute (FIPI); Institute of Forest Ecology & Environment (Vietnam); Forest Inventory & Planning Division (Laos); National University of Laos; Department of National Parks, Wildlife & Plant Conservation (DNP, Thailand); Geo-Informatics & Space Technology Development Agency (GISTDA, Thailand);  and the Forest Research & Training Centre (FRTC, Nepal). In addition, members of SERVIR from both the Mekong and Hindu Kush Himalaya regions attended. 

Over 20 representatives from six countries (Thailand, Nepal, Myanmar, Vietnam, Cambodia and Laos) participated in the workshop. The attendees had a range of expertise, with backgrounds in engineering, geography, computer science, remote sensing, forestry and Geographic Information Systems (GIS). Most of the attendees support forest monitoring and reporting activities as part of their work. Participants left with the tools needed to explore how this technique can be integrated into their work with land classification, carbon pool estimation, and forest monitoring.   


Participants engaged in hands on exercises using ALOS PALSAR-1 L-Band SAR data from the Japan Aerospace Exploration Agency (JAXA) and LiDAR-based tree heights to estimate forest stand height in central Maine, US. This exercise is available in Appendix C of the SAR Handbook

We focused on the temporal decorrelation method of estimating forest stand height (FSH) as described in the SAR Handbook chapter four by Paul Siqueira. Siqueira, Yang Lei, and other authors published a novel approach to estimate FSH above 10m in 2019. The temporal decorrelation method relies on the assumption that if a sensor captures two snapshots of the same area of forest at different times, the sensor will measure a change between the two scenes. On average, the taller the trees the more change the sensor will detect. The algorithm takes the relationship between known tree heights and the amount of change detected by the sensor, and applies that relationship to areas where no known tree height measurements exist in order to estimate forest stand height. 


One method of estimating forest stand height is temporal decorrelation (Source: The SAR Handbook/Leah Kucera)

Participants left with a concrete understanding of how to apply these techniques to their own countries for MRV (Monitoring Reporting and Verification) and land classifications. One participant commented, “This training revolutionize[d] my concept of boring and complex coding to fun and powerful way[s] of analyzing Earth Observation data in an understandable way.” I look forward to working on improvements to the forest stand height estimation algorithm with the SERVIR network and building upon the relationships established during the workshop to estimate forest stand height in their respective countries. After the launch of NASA-ISRO Synthetic Aperture Radar (NISAR)  mission in 2021, we will be able to adapt our methods to include NISAR’s current and more frequent global L-band SAR dataset.