Time Will Tell
Climate is the prevailing condition that you plan for. Weather is what you get. The difference between the two is simply time. For decades, weather satellites have helped us plan our days' activities. Collecting and analyzing these data over time has resulted in more accurate weather forecasts. Similarly, predicting climate involves long-term studies of Earth's interconnected ocean and atmosphere system.
Pioneer Days
These research-and-development (R&D) satellites paved the way for today's – and tomorrow's – observations of our ocean, aerosols, and clouds.
From R&D to Climate Studies
Over two decades later, in 2005, NASA's Earth-observing fleet had grown in size and scope. Dedicated ocean satellites observed color (SeaWiFS), sea level (TOPEX, Jason-1) and winds (QuikSCAT). Continuing measurements that began with Nimbus-7, atmospheric ozone was being monitored by Aura and the Total Ozone Mapping Spectrometer - Earth Probe (TOMS-EP) satellite. Aerosol and cloud research was fueled by imager data from the Moderate-resolution Imaging Spectroradiometer (MODIS) on the Earth Observing System Aqua and Terra satellites, along with Terra's Multi-angle Imaging SpectroRadiometer (MISR).
Climate Data Continuity
Comparing NASA's 2005 and current fleet of Earth satellites tells the story of persistence and change. Veteran sensors have been joined by newer active-sensor orbiters such as CloudSat and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations), which are used to study the effects of clouds and aerosols on climate and weather. The MODIS imager was the pathfinder sensor for the new Visible/Infrared Imager and Radiometer Suite (VIIRS) on Suomi-NPP that will also fly on future NOAA operational polar orbiting satellites.
Significant to understanding climate, MODIS instruments on Terra and Aqua have provided over 15 years of data on aerosol and cloud properties while extending ocean color records beyond 2 decades. Efforts have begun to extend NASA records into the VIIRS era.
Ocean-Aerosols-Clouds
What's the connection?
Let's begin to answer this complicated question with one example of a sequence of events...
Some aerosols in the atmosphere have a chemical composition that can trigger water droplet formation that eventually creates clouds. In fact, without such aerosols, clouds would not form.
Sea salt is not the only type of aerosol emitted from the ocean surface. Microscopic ocean plants and algae, known as phytoplankton, can also produce organic compounds that seed cloud formation.
Aerosols both leave and enter our seas, adding complexity to another example ocean-cloud story...
These ocean-based scenarios involve atmospheric aerosols and cloud formation, two variables that create the most uncertainty about how future climate change will unfold.
Why?
Low clouds predominantly reflect the sun’s rays to cool Earth's surface...
... while high thin clouds predominantly trap outgoing heat that would otherwise be emitted to space.
Likewise, some aerosols scatter light and cause a cooling effect...
... while others absorb light and cause a heating effect.
The connections between aerosols and clouds are more complicated still. For example, interactions in which cloud drops form on aerosols - and aerosols are themselves washed out of the air by rain - are not well understood and indeed may depend on the types of clouds and aerosols involved.
To predict climate, we need to continue monitoring Earth's ocean-aerosols-cloud system with ever-improving technologies that address:
- What are the long-term changes in aerosol and cloud properties that can continue to be revealed by satellites? How are these changing properties interconnected with variations in climate?
- How do aerosols influence ocean ecosystems and cycling of matter in our ocean? Conversely, how do ocean processes affect our atmosphere?
These questions will be tackled by the PACE satellite, scheduled to join NASA's Earth Observation Fleet in 2022.
References
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- Commonwealth Scientific and Industrial Research Organization, Understanding Climate Variability and Change
- Dodd, S., 2008, DMS: The Climate Gas You've Never Heard Of, Oceanus Magazine, 46(3)
- eoPortal, Nimbus-7
- eoPortal, SeaSat Mission — the world's first satellite mission dedicated to oceanography
- Graham, S., 1999, Clouds & Radiation
- King, M., and Herring, D., 2001, Research Satellites for Atmospheric Science, 1978-Present
- Kuring, N., 2016, Northwest Arabian Sea, Ocean Color Image Gallery
- National Park Service, Fire and Aviation Management—More than Meets the Eye
- NASA, 1996, Atmospheric Aerosols: What Are They, and Why Are They So Important?
- NASA, 2012, Cloud Streets Off of the Aleutian Islands
- NASA, 2016, TOMS-EP
- NASA, 2017, Earth Science
- NASA, 2017, Aqua - Project Science
- NASA, 2017, Terra - The EOS Flagship
- NASA Earth Observatory, 2005, Phytoplankton in the Arabian Sea
- NASA Goddard Space Flight Center, 2017, Clouds and the Earth's Radiant Energy System (CERES)
- NASA Goddard Space Flight Center, 2017, Suomi-NPP (National Polar-orbiting Partnership) Mission
- NASA Goddard Space Flight Center, 2017, Visible Infrared Imaging Radiometer Suite (VIIRS)
- NASA Jet Propulsion Laboratory / California Institute of Technology, 2013, NASA Study Eyes Soot's Role in 1800s Glacier Retreat
- NASA Scientific Visualization Studio, 2005, NASA's Orbiting Earth Observing Fleet
- NASA Scientific Visualization Studio, 2009, Aerosols Impact Cloud Formation
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- NASA Scientific Visualization Studio, 2017, NASA's Earth Observing Fleet
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- Voiland, A., 2010, Aerosols: Tiny Particles, Big Impact