New-generation satellite observations monitor air pollution during COVID-19 lockdown measures in California

Written by Dr. Aaron Naeger

Preventative measures recently adopted to prevent further spread of COVID-19 in the U.S. have prompted an overall slowdown in economic activity and fewer vehicles on the roadways.  Since combustion engine powered vehicles can represent a major source of nitrogen dioxide (NO2) emissions, less traffic on the roadways may lead to a significant reduction in NO2 concentrations and, as a result, fine particulate matter (Particulate Matter less than 2.5 microns in diameter or PM2.5) as NO2 emissions are a known precursor to PM formation.

The Tropospheric Monitoring Instrument (TROPOMI), launched in 2017 as part of the polar-orbiting European Space Agency’s (ESA) Sentinel-5 precursor (Sentinel-5P) satellite, has advanced our capability to monitor fine-scale emission sources, including vehicular emissions along traffic corridors, with unprecedented spatial resolution of 5.6 x 3.5 km2.  Daily midday scans of TROPOMI over the densely populated cities and heavily trafficked corridors in California during March 2020 show how the adoption of stricter COVID-19 measures have impacted air quality in the state.  To effectively examine the changes in air quality in California, we constructed weekday averaged NO2 maps for March at 0.05° grid spacing from high-quality, cloud-free retrievals provided by TROPOMI level 2 data.  It is also important to note the role of natural weather variability on air pollutants during this seasonal transitional period, as warmer temperatures and higher mid-day solar angles lead to shorter NO2 lifetimes and generally lower NO2 column concentrations.


Figure 1. a) Gridded 0.05 x 0.05° NO2 map from TROPOMI Offline (OFFL) L2 retrievals during 2-6 March 2020 (pre-shutdown) over California.  b-d) Same as a), except valid for b) 9-13 March during soft shutdown measures, c) 16-20 March when “shelter in place” orders were announced, d) full period of “shelter in place” orders during 23-27 March. Panel d) generated using near real-time (NRT) product due to 7-10 day lag of OFFL product.

For the first weekday period of March (2-6 March) when COVID-19 measures were yet to be implemented, the largest tropospheric NO2 concentrations were observed in Los Angeles and bordering counties with a less prominent peak in NO2 around San Francisco (Fig. 1a).  The TROPOMI scans also resolved areas of enhanced NO2 along the heavily trafficked corridor of State Route 99 (SR-99) in the Central Valley, particularly around the cities of Bakersfield and Fresno.  As initial, soft COVID-19 measures were adopted by businesses in California during the second weekday period in March (9-13 March), TROPOMI observed strong reductions in tropospheric column NO2 around the large cities of Los Angeles and San Francisco along with noticeable decreases along SR-99 (Fig. 1b).  As California announced statewide “shelter in place” orders during the third weekday period of March (16-20 March), further decreases in NO2 were apparent throughout all populated areas in the state and along SR-99 (Fig. 1c).  Noticeable decreases in NO2 continued throughout much of the state during the fourth weekday period of March (23-27 March), especially around San Francisco (Fig. 1d).  Overall, these observed reductions in TROPOMI NO2 throughout March are the result of decreased emissions on top of the seasonal changes in meteorological conditions.

SPoRT Graduate Student Spotlight: Holley Kenward

Written by Ben Houser

SPoRT is home to several graduate researchers, who are each working on completing the research required to earn their master’s degrees. Previously, we have featured the work of Sebastian Harkema, Angela Burke, and Abby Whiteside. Now, we are featuring Holley Kenward and her research into tropical cyclones. Holley has completed her undergraduate degree in Earth System Science with a concentration in Atmospheric Science at the University of Alabama in Huntsville.


Holley presenting her research at the Marshall Space Flight Center Jamboree in February of 2020

Holley is researching the diurnal cycles of tropical cyclones, or the daily patterns of tropical cyclones’ intensity and structure. By studying these daily changes in tropical cyclones, Holley is discovering how they impact changes in tropical cyclones’ moisture content. Along with data from a numerically simulated cyclone, Holley uses observations of Hurricane Dorian, which struck the Bahamas with extreme intensity in 2019, to conduct her research. Using imagery from the GOES-16 satellite series and NUCAPS weather soundings, Holley has discovered a distinct diurnal cycle in Hurricane Dorian. In other words, the hurricane exhibited a daily pattern of increase in size and water vapor content that occurred on multiple days. The same diurnal cycle was found in Holley’s numerically simulated hurricane, indicating the great potential of her research. As NASA prepares to launch the TROPICS satellites series, which will provide groundbreaking observation of tropical storms, Holley is working with TROPICS proxy data in her research to determine the data’s potential for understanding hurricanes.


GOES-16 Low-level Water Vapor in Hurricane Dorian at 3 and 16 Local Time on August 28, 2019. The black rings are every 100km from storm center. There is a very clear increase in overall storm size and water vapor content in the afternoon denoting the diurnal cycle change within Hurricane Dorian.

Holley learned about SPoRT as a freshman at UAH, when she played for the atmospheric science department softball team with a few SPoRT graduate students. As a senior about to graduate, Holley reached out to SPoRT to ask about graduate research positions. When she found about the TROPICS mission and the research associated with it, she was sold!

Holley’s favorite part of working for SPoRT has been the opportunities it has provided her. With the help of SPoRT, Holley has presented her research at the Marshall Space Flight Center Jamboree in February, and has attended the 2nd TROPICS Applications Workshop in Miami, FL. Holley appreciates SPoRT’s help with meeting and learning from other scientists, and the amount of learning she finds within the department itself. She also enjoys doing research that will go into a useful product for operational meteorologists.

In the future, Holley plans on finishing up her masters. When she graduates, Holley would love to continue working with SPoRT, but will be happy as long as she can keep studying tropical cyclones!

2nd NASA TROPICS Applications Workshop in Miami, FL

2nd NASA TROPICS Applications Workshop in Miami, FL

By Ben Houser

            On February 19 and 20, 2020, the second TROPICS (Time-Resolved Observations of Precipitation Structure and Storm Intensity with a Constellation of Smallsats) Applications Workshop occurred in Miami, FL. The workshop’s purpose was to both connect scientists with TROPICS early adopters, or scientists who are performing pre-launch research to determine the mission’s capabilities, and potential end-users, and to discuss the mission’s status and direction. The workshop was organized by SPoRT scientist and TROPICS Deputy Program Applications Lead Dr. Emily Berndt, and University of Miami and NOAA/Hurricane Research Division scientist Dr. Jason Dunion. Along with Dr. Berndt, SPoRT scientists Dr. Erika Duran, Dr. Patrick Duran, and graduate student Holley Kenward attended the conference to engage with early adopters. Attendees included algorithm developers, applied researchers, forecasters, and international representatives from Brazil’s National Institute for Space Research, Météo France, and the European Centre for Medium-Range Weather Forecasts.

TROPICS is a series of small satellites launching no earlier than 2021 that will measure the temperature, humidity, and precipitation of tropical regions with state-of-the-art accuracy and unprecedented frequency. TROPICS’s primary mission objective is to provide a means for end-users to observe hurricanes, and the satellite series will be able to provide high-resolution data of both a hurricane’s eye and the surrounding environment. Using TROPICS, scientists will be able to understand the relationship between temperature, humidity, and precipitation as a hurricane evolves. In 2018, the SPoRT team began the TROPICS Early Adopter program in order to connect potential end-users with TROPICS researchers.

The workshop’s primary purpose was to connect early adopters and potential end-users to TROPICS’s Science Team. Early adopters shared their results and expressed successes, challenges, and future needs. Furthermore, early adopters helped identify technical and visualization enhancements which would make TROPICS data easy to use in a broad range of applications and enable users to quickly adopt the data after launch. During breakout sessions, attendees discussed mission latency, needs for tools and visualizations, and the strengths/limitations of using small satellites in applied research and operations (Fig. 1).

Fig 1: Attendees at the 2nd TROPICS Applications Workshop discuss the value of TROPICS products to support research and applications related to tropical cyclone analysis and forecasting during a breakout session on community needs for products, tools, and visualizations. Right to Left: Holley Kenward (Univ of Alabama in Huntsville-NASA SPoRT), Jason Dunion (Univ of Miami/CIMAS- NOAA/HRD), Derrick Herndon (Univ of Wisconsin-Madison/CIMSS), Stephanie Stevenson (CIRA/NHC), Erika Duran (Univ of Alabama in Huntsville-NASA SPoRT) and Patrick Duran (NASA MSFC SPoRT).

            During the workshop, presentations were given by SPoRT scientists Dr. Emily Berndt and Dr. Erika Duran. Dr. Berndt, who organized the event with Dr. Jason Dunion, presented on the workshop’s plan and expectations and introduced the objectives of each breakout session. Dr. Duran presented on her research analyzing hurricanes using TROPICS proxy data, which is data that mimics what TROPICS data will look like once launched (Fig. 2). Further presentations were given by other scientists on applied research, modeling, and applications relating to precipitation, disasters, and severe weather.

Fig 1. Comparison of temperature between a simulation of a hurricane (blue line) and TROPICS proxy data (green line). Snapshots of temperature are taken at midnight (0:00 local time) just outside the core region of the hurricane. The general similarity of the shape and sign of both temperature profiles suggest a good agreement between the two datasets.

New NUCAPS Training & Resources

SPoRT has been part of a multi-organizational collaboration within the JPSS Sounding Initiative to develop products from Hyperspectral Infrared Sounders and assess the utility of the new observations in the operational environment.  Many of the products and capabilities start out as a “proof of concept” and are then introduced to end users to incorporate end user feedback into the design and implementation process, one example of this is Gridded NUCAPS.   The team has focused on satellite soundings processed through the NOAA Unique Combined Atmospheric Processing System (NUCAPS) which is the NOAA operational satellite sounding retrieval algorithm for hyperspectral infrared sounders on S-NPP and NOAA-20.  Currently NOAA-20 NUCAPS Soundings and Gridded Products are available to all National Weather Forecast Offices.   A recent article “Adapting Satellite Soundings for Operational Forecasting within the Hazardous Weather Testbed” highlights the applied research, assessment of satellite soundings in a quasi-operational setting, and the role of end-user feedback in adapting products/capabilities to meet end users’ needs.  The team comprised of algorithm developers, product developers, and end users has found ways to interact, translate science to operations/operations back to science, leveraging the cross-benefit of science and applications to guide applied research to improve satellite sounding algorithms and products.

The success of NUCAPS for the Cold Air Aloft aviation hazard and diagnosing the pre-convective environment along with the accessibility of NUCAPS products to end users has led to applied research to assess the utility of products for additional applications (Berndt et al. 2020).  NASA’s 2017 Decadal Survey points out “The final missing piece of applications research in the agencies is the very initial phase of creating applications—supporting studies that have an idea about how an application might work, and then attempting to create a community for it, and demonstrate its utility”.  There are complex barriers that exist when identifying end users and transitioning relevant data to meet their needs.  As pointed out by NASA’s 2017 Decadal Survey  “… the applications field is becoming associated with a science of its own…”  Recently, SPoRT has investigated the utility of NUCAPS products for fire weather applications as a “proof of concept”.  As SPoRT engages with users on application of NUCAPS observations, a new interactive training  was developed to communicate the value and utility of these data.  SPoRT has found that creating short, focused, applications-based training can remove some barriers to end users integrating new data and capabilities in operations.   Last SPoRT has created a NUCAPS webpage where scientist and users can find information relevant to NUCAPS products, resources such as training, blogs, peer-reviewed literature, and data access.


New Interactive training on application of NUCAPS products to assess fire weather conditions –> Go to training


NUCAPS resource webpage for scientists and end users –> Go to webpage



SPoRT Graduate Student Spotlight: Abby Whiteside

Written by Ben Houser

SPoRT is home to several graduate researchers, who are each working on completing the research required to earn their master’s degrees. Last week, we featured Angela Burke’s research into “false alarms” in SPoRT’s imaging software. In this article, we are spotlighting the work of SPoRT graduate researcher Abby Whiteside. Like Angela, Abby has completed a bachelor’s degree in Earth System Science with a concentration in Atmospheric Science at the University of Alabama in Huntsville. Abby is now researching the impact and nature of hail damage.

Abby Whiteside presenting her research at the annual American Meteorological Society conference.

When a thunderstorm produces a significant amount of hail damage, it creates a hail scar, which is an observable area of large hail damage to the environment, such as a long streak of dead vegetation. Abby is working to better understand storms that create these hail scars. She utilizes data from the GOES-R satellite series’ Advanced Baseline Imager (ABI) and Geostationary Lightning Mapper (GLM) in conjunction with radar data to understand the characteristics and inner-workings of hail scar producing storms. In order to find out why specific storms cause hail damage, Abby compares the storm structures of hail scar producing storms and non-damaging storms. By combining different data sources, Abby can get a more thorough understanding of the way hail producing thunderstorms work. Abby said that she really enjoys working with satellite data, so this project was a unique opportunity that she couldn’t pass up. 

Abby’s thesis is a part of a larger collaboration between SPoRT, NASA’s Langley Research Center, and the Marshall Space Flight Center. Abby started working at SPoRT in 2019, after she crossed paths with SPoRT scientists Dr. Chris Hain and Dr. Chris Shultz during an internship with NASA Develop, where SPoRT was a partner. 

An Above Anvil Cirrus Plume that manifested from an Overshooting Top producing storm. This storm produced large amounts of hail damage in Nebraska and Wyoming

Abby’s favorite part of working with SPoRT has been the opportunity to work on solving a problem that has never been thoroughly examined by the meteorology community. She also enjoys finding trends in the GOES-16 satellite’s GLM data. Since the GLM is a newer product, Abby was excited about the opportunity to use its data to support the satellite community. Abby also appreciates working with experts from different areas of meteorology, and attending meteorology conferences is a highlight of her job.

In the future, Abby plans to finish her master’s degree with SPoRT. After completing her masters, Abby hopes to use her expertise in meteorology in support of NASA’s future exploration missions.

A first look at GLM observations of the supercell thunderstorm responsible for tornadoes in Tennessee on March 2-3 2020

Written by Chris Schultz

Overnight on March 2-3, 2020, several severe thunderstorms affected parts of Missouri, Arkansas, Kentucky, and Tennessee, with the most notable damage occurring around the Nashville metropolitan area.  At the time of this blog post, storm surveys continue in Tennessee by National Weather Forecast Offices in Nashville and Memphis TN (  ,  This post takes a preliminary look at the electrical characteristics of the thunderstorms responsible for this damage from the lens of the newer instruments on the GOES-R series of satellites, the Geostationary Lightning Mapper (GLM).  GLM measures optical lightning signatures in thunderstorms to determine the spatial extent and frequency of lightning as it propagates through the cloud.

Figure 1 – Flash Extent Density information from the Geostationary Lightning Mapper between 0445 UTC and 0835 UTC.

Figure 1 shows an animation of flash extent density within the NWS primary warning dissemination tool, AWIPS2 between 0445 UTC and 0835 UTC.  Note that there are 3-4 distinct pulses in lightning activity as the storm traverses Central Tennessee.  If we look at a time series of this flash data, there are five distinct rapid increases in the flash rate, known as lightning jumps, were observed (0445 UTC, 0509 UTC, 0545 UTC, 0730 UTC, and 0802 UTC; below, Fig. 2).  Rapid increases in flash rate depicted in Figure 2 are associated to strengthening updrafts in the mid-levels of thunderstorms, where the strengthening updraft facilitates charge separation and an increase in the lightning frequency.

Figure 2 – Time trend information of the maximum flash extent density value aggregated over a five minute period, updated every one minute between 0445 UTC and 0840 UTC.

Examining the initial lightning jump, there are notable differences in storm structure when the pre-jump and post-jump radar images are compared (Figure 3).  The first main difference is the notable bounded weak echo region (BWER) in the horizontal reflectivity data (Panels A vs F).  Cross section of reflectivity also show an increased depth of the BWER in Panels E and J.  The second notable difference is the increase in low-level rotation in radial velocity between Panels B and G. Research completed at UAH indicates that 77% of the time a lightning jump was observed in a sample of 19 supercell events, low and mid-level rotation increased, similar to what is observed in this time period.  The first severe weather reported with this storm was at 0507 UTC with 1.50 inch hail falling near Camden, Tennessee.

Figure 3 – 10 panel image of radar information from the National Weather Service Radar at Ft. Campbell, Kentucky at 0445 UTC and 0456 UTC. Panels A and F are horizontal reflectivity at 0.5 degrees elevation, B and G are radial velocity, C and H are differential reflectivity, D and I are correlation coefficient, and E and J are vertical cross sections of the storm through the center of the mesocyclone region.

Another observation is the relative lull in lightning activity around 0620 UTC through 0730 UTC. It is unclear at this point in time of the specific start time of the tornado that tracked from Nashville to Mt. Juliet due to ongoing surveys; however, radar data indicates lofted debris from the tornado as early as 0636 UTC (Figure 4A), lasting all the way to at least 0733 UTC (not shown). Previous work on lightning lulls near the time of tornadogenesis theorize that the lack of lightning is due to weakening vertical motion in the mixed phase region as downdraft processes in the thunderstorm taking over.

Figure 4  – Two panel radar image from KOHX in Old Hickory, Tennessee at 0636 UTC, when the first instances of a tornadic debris signature was present, confirming the tornado’s presence at the surface.

It must be emphasized that the low and mid-level rotation increases do not directly correspond to the development of tornadoes because the processes that are responsible for tornadogenesis are found within the lowest 1 km of the atmosphere, while those related to lightning generation are generally above 4 km. However, forecasters within the NWS have been able to combine the lightning, radar, and local environmental data to anticipate potential strengthening of a thunderstorm in specific severe weather environments (e.g., ).

Additional details on storm evolution will unfold as the NWS offices complete their surveys. We will be looking into the resurgence in flash rates around 0730 UTC as the storm moved eastward from Nashville and Mt. Juliet. Additional damage was reported near Cookeville, Tennessee, but radar data at this time do not allow us to confirm any details on this portion of the storm’s lifecycle.

SPoRT Graduate Student Spotlight: Angela Burke

Written by Ben Houser

SPoRT is home to several graduate researchers, who are each working on completing the research required to earn their master’s degrees. Previously, we featured Sebastian Harkema’s trip to NASA’s Wallops Flight Facility as a forecaster for the IMPACTS campaign. This week, we are spotlighting the work of another graduate student: Angela Burke. Angela has completed a bachelor’s degree in Earth System Science with a concentration in Atmospheric Science at the University of Alabama in Huntsville, and is now working on exciting research with SPoRT.

Angela Burke, one of SPoRT’s graduate researchers.

Angela Burke is now a graduate researcher, but began working for SPoRT as an undergraduate in 2016. Her current research concerns issues with the algorithms used to create SPoRT imagery products from the GOES-R satellite series’ Advanced Baseline Imager; the ABI is the series’ primary instrument responsible for imaging Earth’s weather and climate. Sometimes, the ABI picks up signals from the surface that mimic the signal SPoRT’s algorithms associate with a low cloud, creating a “false alarm” in the data. Angela is hoping to understand and correct these false alarms, especially in SPoRT’s Nighttime Microphysics RGB product.

The NASA SPoRT Nighttime Microphysics RGB focused on the Southwestern U.S., highlighting the similarity between the “false alarm” regions and actual marine stratocumulus clouds.

Angela’s favorite part of working with SPoRT has been the unique opportunities it has provided. Since she began her undergraduate degree at UAH, Angela has quickly made a name for herself in the field of atmospheric science, and SPoRT has been there in support along the way. Angela began working at SPoRT in the fall of her sophomore year, and the following spring she was awarded the competitive NOAA Hollings Undergraduate Scholarship, which earned her a ten-week research position at NOAA’s Cooperative Institute for Research in the Atmosphere, in Fort Collins, Colorado. In the summer of 2017, Angela interned at the Department of Energy’s Oak Ridge National Laboratory, where she collaborated with SPoRT to analyze satellite imagery of power outages after natural disasters. In the summer of 2019, Angela worked at the Jet Propulsion Laboratory in California, where she researched Jupiter’s polar atmosphere. Angela’s time at SPoRT has provided her with research opportunities, support, and professional connections.

Angela seems to have a bright future ahead of her. She plans on finishing up her master’s degree with SPoRT, hopefully fixing the Nighttime Microphysics RGB imaging issue while she is at it. After completing her masters, Angela plans to pursue a PhD in Planetary Science.