Tracking Earth’s Climate from Space
More than sixty years ago, the first satellite launches captured the attention of the world. Astronauts followed soon after, and the concept of space exploration leaped from science fiction into reality.
Fast-forward to the new millennium. Space travel and more importantly, satellite technology, have evolved since those early days. At the same time, the world has a whole new set of problems to solve.
The U.S. Government's National Aeronautics and Space Administration (NASA) continues to occupy a lead role globally in the exploration of the skies. Of its many facilities, the Jet Propulsion Laboratory (JPL) in La Canada Flintridge, California, stands out as a premier facility for satellite technology. JPL has many satellite projects that gather valuable information about a multitude of subjects. It may come as a surprise to learn that not all these projects examine far-flung, extraterrestrial phenomena, such as pulsars and black holes. Many are gathering data that is vital to the study of problems right here on Earth. Of these, none is more pressing than climate change.
Rendering Islands of Heat
Global warming has manifested itself in many ways.
For example, the accentuated effect of global warming's rising temperatures has been documented in urban environments. While buildings, roads, and other infrastructure give cities their unique character and iconic profiles, these man-made structures also absorb and re-emit the sun’s heat to a much greater degree than do natural landscapes, such as forests and water bodies.
According to the U.S. Environmental Protection Agency (EPA), studies and data have found that in the United States, the heat island effect results in daytime temperatures in urban areas about 1–7°F higher than temperatures in outlying areas and nighttime temperatures about 2–5°F higher. When coupled with the already rising temperatures caused by the effects of greenhouse gases, this serves to only compound the problem for the occupants of cities, which is where more than half of the world's population (56%) resides.
Data measuring heat islands is one of the products of the JPL ECOSTRESS mission. The device has been deployed on the International Space Station (ISS) since 2018, when it was launched on a SpaceX Dragon. It consists of a thermal radiometer which measures radiation emitted from the Earth's surface. The radiometer consists of a scanning mirror and telescope to focus the energy from a small spot on the Earth onto a very sensitive infrared detector. ECOSTRESS can map 90% of the continental United States in less than four days.
Simon Hook, Principal Investigator for JPL on the ECOSTRESS project, describes the sophistication of the instrumentation. "We can measure the surface temperature of the Earth within a few tenths of a degree," he explains. "Measurements can be made in microseconds."
The objective of the mission is to measure variations in ground temperatures to indicate how plants respond to water shortages. This will provide vital information to those studying the impact of drought and water use on agricultural practices.
The information has also proved useful in the examination of heat islands. The JPL radiometer has produced a number of images that render the impact of extreme heat in urban environments. For example, an image posted to the mission website illustrates the dynamics of a heat wave that occurred in Las Vegas in June of this year. Air temperatures reached 109°F, but surface temperatures on the city's streets were much higher. The JPL images, where heat is rendered in various shades of red, show a grid pattern, mirroring the city's streets, where temperatures were measured in excess of 120°F.
Heat islands present many problems for urban residents related to energy consumption and health. In some cases, the effects can contribute to higher mortality rates in heat waves. Taking account of heat islands can result in solutions that lessen their impact. The data that ECOSTRESS provides can help with the development and evaluation of those solutions.
For example, the City of Los Angeles used ECOSTRESS to measure the impact of a test project to lower temperatures from paved surfaces. The city's Bureau of Street Services applied a cooling layer of white "paint" to certain test spots around the city. After application, the city measured the effects. Using data from ECOSTRESS, the city confirmed that the paint application had resulted in a temperature difference of 13°F between street surfaces in the same neighborhoods that had been painted and those that had not.
Measuring the Dynamics of Dust
JPL satellite technology is being used in other projects to study the effects of global warming. The Earth Surface Mineral Dust Source Investigation, (EMIT) will analyze dust carried through the atmosphere from dry regions to see what effects it has on the planet.
Why dust? It's a fair question. After all, it is just, well, dust.
The impact of these airborne clouds of sand and dirt is far greater than what the diminutive size of the individual particles would suggest.
Across the globe, strong winds carry clouds of dust in concentrations that reach mammoth proportions. According to NASA, each year, strong winds carry more than a billion metric tons of mineral dust, equal in weight to 10,000 aircraft carriers. These clouds travel from Earth’s deserts and other dry regions through the atmosphere.
Across the globe, strong winds carry clouds of dust in concentrations that reach mammoth proportions.
Scientists know that the dust affects the environment and climate, but they don’t have enough data to determine, in detail, what those effects are or may be in the future. EMIT can provide them with the data they are looking for.
The state-of-the-art spectrometer was developed at JPL and launched to the International Space Station in June of this year. The instrument will collect more than a billion dust-source-composition measurements around the globe over the course of a year.
Robert Green, Principal Investigator for the project at JPL, describes how each particle of dust is unique. "They give us signatures, like fingerprints." The instrument can detect these unique characteristics. It is "setting a new benchmark for the quality of this class of instrumentation," he explains.
The information gathered by EMIT will contribute to scientific understanding of atmospheric dust clouds in five distinct ways.
First, it will identify the composition of mineral dust from Earth’s remote and inaccessible desert regions. EMIT provides information on the color and composition of dust sources globally. This data will help scientists understand which kinds of dust dominate in particular regions, and it will advance their understanding of dust’s impact on climate and the Earth system.
Secondly, EMIT data will clarify whether mineral dust heats or cools the planet. Currently, scientists aren't sure about the heating and cooling properties of dust because particles have different properties based on their color, which will determine if they absorb or reflect heat. EMIT will provide a detailed picture of how much dust comes from dark versus light minerals.
Third, EMIT will help scientists understand how dust affects different Earth processes. Mineral dust particles vary in color because they’re made of different substances, such as iron, calcite or chlorite, and these substances have varying properties which can impact Earth systems in different ways.
For example, mineral dust plays a role in cloud formation and atmospheric chemistry. When mineral dust is deposited in the ocean or forests, it can provide nutrients for growth, acting like fertilizer. When it falls on snow or ice, the dust accelerates melting, leading to more water runoff. And for humans, mineral dust can be a health hazard when inhaled.
Fourth, EMIT will improve the accuracy of climate models. The data provided by the project's instruments will allow scientists to more accurately render the color and composition of atmospheric dust, and therefore to understand the effects this dust may have on climate, and that climate may have on the dust.
Fifth and finally, EMIT will help scientists more accurately predict how future climate scenarios will affect the type and amount of dust in our atmosphere. As global temperatures rise, arid regions may become even drier, resulting in larger deserts with even more dust. With the help of EMIT, scientists will gain a better understanding of this compounding effect and the "feedback loop" it may have on climate itself.
Understanding Global Warming from the Skies
JPL and NASA have many other satellite projects underway, analyzing the endless mysteries of our skies. While "enchanted rocks" on Mars and life on distant worlds may grab headlines and pique the imagination of viewers at home, studies of Earth phenomena have equal importance. As the study of climate change becomes more earnest, the data from these projects carry greater significance and may lead to solutions that can help mankind ameliorate and cope with the monumental changes it faces.
*Rick Laezman is a freelance writer in Los Angeles, California, US. He has a passion for energy efficiency and innovation. He has been covering renewable power and other related subjects for more than ten years.