This advanced lidar has successfully captured intricate 20 km-high vertical profiles of atmospheric aerosols-tiny particles and droplets originating from both natural events like wildfires, dust storms, and sea spray, as well as human activities such as industrial emissions and wood burning-and clouds across different global regions.
The lidar operates by emitting pulses of ultraviolet light and analyzing the reflected signals to measure the distribution and characteristics of aerosols and clouds, including their altitude, thickness, optical properties, and physical structure.
Collaborating with EarthCARE's other three instruments, the atmospheric lidar plays a key role in advancing our understanding of aerosols and clouds' contributions to Earth's energy balance. Additionally, this data is expected to be valuable for enhancing air quality forecasts.
The first image, captured by the atmospheric lidar on August 2, showcases a profile of polar stratospheric clouds over Antarctica. The accompanying grey strip represents the corresponding area captured in the infrared spectrum by EarthCARE's multispectral imager, providing a natural visual context for the collected data.
Polar stratospheric clouds are significant in the depletion of stratospheric ozone during the winter and spring months. These clouds facilitate chemical reactions that release chlorine free radicals, which actively destroy ozone molecules, contributing to the formation of the ozone hole over Antarctica.
The jagged appearance of clouds in the center-right of the image is likely due to gravity waves. These waves occur when air is pushed upwards into a stable atmospheric layer, after which gravity pulls it back down, creating a ripple effect similar to ocean waves.
These gravity waves transport energy and momentum from the lower atmosphere to higher altitudes, influencing weather patterns and atmospheric circulation, which in turn affects the formation of polar stratospheric clouds.
The second image, captured on August 4, shows a strip over North America, where Tropical Storm Debby is visible over the Gulf of Mexico, along with large convective clouds further north. Due to the optical thickness of these clouds, the lidar captures details of their tops but cannot penetrate to see below.
Additionally, a prominent red layer of aerosols is visible in the central part of the profile, indicating smoke carried by the wind from prolonged forest fires in several regions of Canada.
Smoke from wildfires has complex effects on climate change, influencing weather patterns and accelerating global warming, while also impacting air quality when it lingers close to the ground.
Below this dense smoke layer lies a more diffuse concentration of aerosols from various sources.
The third image, taken on August 3 over the mid-Atlantic, is particularly rich in detail. It reveals high-altitude cirrus clouds, deep convective clouds, and low, thin clouds. The profile also includes two distinct types of aerosols: marine aerosols, such as salt spray from the ocean, and a thick dust layer originating from the African Sahara desert.
Understanding the complex interactions between these clouds and aerosols in tropical regions is crucial for predicting changes in Earth's climate.
The final image, captured on August 2 over Africa, features high convection clouds and a dense layer of aerosols from biomass burning, a common occurrence during this time of year across large parts of the continent. These fires are mostly set to clear forests or old crops to make way for agricultural land.
ESA's Director of Earth Observation Programmes, Simonetta Cheli, commented, "Following on from the first images from EarthCARE's other three instruments, we can now also see how well the atmospheric lidar is working. These profiles from the atmospheric lidar come exactly as we had anticipated, after the instrument has been through its routine decontamination and calibration processes."
"The atmospheric lidar brings us completely new insight into the vertical distribution of clouds and aerosols and, together with the other instruments, puts us on course to gaining new scientific understanding into Earth's energy balance."
As part of ongoing efforts to validate EarthCARE's instruments, a comprehensive field campaign, ORCESTRA, is now in progress. This international initiative combines eight sub-campaigns involving measurements from aircraft, ships, and ground-based instruments, which are compared with EarthCARE's data. Some measurements are carefully timed to coincide with EarthCARE's overhead passes. Additionally, NASA's ARCSIX campaign also under-flew EarthCARE with their lidar and multispectral imager.
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