Satellites, Scientists, and Storms

Orbiting Carbon Observatory 2

By Ann Gill (M.A., ’76)

Colorado State University’s Atmospheric Science Department has an outstanding reputation and attracts top-quality graduate students. Among its impressive alumni are four who use satellite- and airplane-gathered data to study clouds, lightning, precipitation, and related phenomena. Three work at NASA sites; one is a faculty member whose research uses NASA satellite data.

How did these four become interested in atmospheric science? The most recent graduate, Rob Nelson (M.S., ’15; Ph.D., ’19), developed his interest in an earth science class in high school. Anita Rapp (M.S., ’04; Ph.D., ’08) grew up in the Texas Panhandle, an area known for dramatic weather. She and her father had “a ritual of cloud watching” that began with a stop at Dairy Queen for an ice cream cone followed by a drive out of town to watch the storms move in. Timothy Lang (M.S., ’97; Ph.D., ’01) spent hours watching thunderstorms at a lake cottage in Minnesota. Walt Petersen (M.S., ’92; Ph.D., ’97) went to a drive-in theatre with high school friends and hung the speaker on the car door. When a thunderstorm came up, a lightning bolt hit the speaker pole, giving a jolt to his friend whose hand was on the speaker. These early experiences have turned into fascinating careers.

Walt Peterson delivering a presentation on Global Precipitation Measurement at NASA's Wallops Flight Facility Visitors Center.
Walt Peterson delivering a presentation on Global Precipitation Measurement at NASA’s Wallops Flight Facility Visitors Center.

Walt Petersen

After a stint as an aerographs mate in the Navy and earning an undergraduate degree in mathematics, Walt Petersen chose to attend CSU to work with Professor Steve Rutledge on a project studying tropical thunderstorms and lightning. He also was attracted because the University had recently received the CSU-CHILL National Science Foundation Radar Facility. CSU gave Petersen “the opportunity to do field work all around the world.” He now is deputy chief of the Science Research and Projects Division at the NASA Marshall Space Flight Center in Huntsville, Alabama. As explained on its website, the Center delivers “vital propulsion systems and hardware, flagship launch vehicles, state-of-the-art engineering technologies, and cutting-edge science and research projects and solutions.”

Early in his career at NASA, Petersen worked on tropical lightning imaging. He also has worked with radar, studying lightning and thunder as a way to understand the hydrologic cycle, and led instrument developments in international field campaigns, including Global Precipitation Measurement (GPM) mission, which involves an international network of satellites that provides the most accurate and comprehensive precipitation data ever assembled, resulting in more accurate forecasting.

Petersen has led eight field campaigns, some of which were international. They have involved data from satellites as well as from NASA aircraft, giving scientists data from high altitude and from inside clouds as well as from earth-bound instruments. He also did a stint as branch chief at NASA Wallops Flight Facility, Maryland, a NASA-owned launch site responsible for commercial resupply of the International Space Station and science missions using sounding rockets.

His recent promotion to a division management position has been “an exciting opportunity” and he “gets to learn more about all NASA science disciplines.” As part of the leadership team, he helps plan and facilitate future NASA research. Petersen was awarded the prestigious NASA Exceptional Scientific Achievement Medal in 2018.

Tim Lang with airplane in background
Timothy Lang with NASA’s P-3B science aircraft.

Timothy Lang

Also at the NASA Marshall Space Flight Center in Huntsville, Timothy Lang is a research aerospace technologist. The combination of a “reformed elementary particle physicist undergraduate professor” and an internship at Goddard Space Center led him to apply for the graduate program at CSU so he could do research on midlatitude and tropical thunderstorms.

These days, most of his research centers on convective storms, including lightning and precipitation. He also works on instrument development for research, leading a project for airborne instrument microwave radiometer. He also is involved in process studies, including what are the processes of clouds in storms, what causes lightning, and what winds are doing in storms.

Recently, Lang was in the Philippines, where NASA’s P-3B science aircraft gathered data to study the impact that smoke from fires and pollution has on clouds and how aerosol particles interact with monsoon meteorology, cloud microphysics, and the sun’s radiation. Lang notes the importance of scientists getting out into the field, which “expands one’s scientific perspective.” Through his research, he has learned that pollution has an “interesting impact” on clouds, and he currently is helping test hypotheses that were developed regarding those impacts. While discussing the devastating fires in Australia, he explained that “smoke in large amounts suppresses clouds, although smoke in small amounts invigorates clouds.”

Rapp displaying her teaching award with Texas A&M President Michael K. Young, left, and Director of the Center for Teaching Excellence Debra Fowler, right.
Anita Rapp displaying her teaching award with Texas A&M President Michael K. Young, left, and Director of the Center for Teaching Excellence Debra Fowler, right.

Anita Rapp

Anita Rapp’s original plan was to be a forecaster. Then she worked with a professor at her undergraduate institution and became interested in atmospheric science research. While there, she had the opportunity to spend two months in the Marshall Islands launching weather balloons and helping with aircraft missions for ground validation of the first satellite precipitation radar.

After graduation, she accepted a position as a contractor with NASA Langley in Virginia, where she used satellite measurements to identify properties of clouds. This experience led her to apply for the graduate program at CSU in order to work with Professor Christian Kummerow doing research using satellite cloud and precipitation measurements. She now is a tenured associate professor at Texas A&M, which has one of the largest undergraduate atmospheric science programs in the country, and where she has won two teaching awards.

Rapp’s research uses satellite observations to understand interactions between environment and clouds, including their radiative effects. Among her findings is that there is more drizzle than had been thought previously in the marine boundary cloud systems and that cloudiness surrounding drizzling clouds decreases much faster than around non-drizzling clouds. These low clouds are important for regulating climate, so understanding these transitions in cloudiness that allow more solar radiation to reach the surface is especially important as the climate warms.

A new project involves studying dynamics and energy of the summer stratosphere, with the goal of understanding how strong summer thunderstorms in the United States transport moisture and pollutants to the upper atmosphere where they can potentially impact stratospheric composition. In addition to providing analysis of radar and satellite data, for the next two summers she will help provide forecasting and support for the NASA ER-2, which is a modified version of a U-2 spy plane outfitted with scientific instruments to collect high altitude measurements.

Rob Nelson hiking
Rob Nelson

Rob Nelson

A recent CSU graduate, Rob Nelson currently is a postdoctoral fellow at the NASA Jet Propulsion Laboratory in Pasadena, California. He and others analyze data from Orbiting Carbon Observatory (OCO) 2 and 3, which are satellites capturing data on carbon. The OCO-2 was launched in July 2014. It is in a sun-synchronous polar orbit making measurements of atmospheric carbon dioxide using reflected sunlight. Among the uses NASA scientists are making of this data are learning about processes that regulate atmospheric carbon dioxide as well as its role in climate.

The OCO-3 was launched in spring of 2019 and is mounted on the International Space Station, which orbits earth from 52 degrees north to 52 degrees south latitudes. It has a special observation mode that allows dense data sets to be collected over urban areas, power plants, and other sites of interest, which will give even more insight into the carbon cycle.

These four amazing Ram scientists are playing critical roles in increasing our understanding of weather and climate change. They each pay tribute to their graduate education at CSU. Peterson urges future atmospheric scientists to attend his alma mater for graduate school and to “surround yourself with excellence. CSU will provide you with lifetime mentors. Take advantage of that…. CSU set the framework for my career.”