Every breath we take, even in clear fresh air, contains millions of tiny particles and droplets. These microscopic bits are called aerosols. They have myriad sources in nature and human-activity such as sandstorms, ocean-spray, volcanoes, forest fires, transportation, power generation, cooking-stoves, industrial sources, and many more. They also are made and modified by chemistry in the air. They are lofted and blown by the winds around the entire hemisphere and cycled among the oceans, atmosphere, and lands.
They have major effects on Earth’s climate and weather. In fact, if there were no aerosols, there would be no clouds, since cloud droplets need these tiny "seeds" to help them form. In this way, aerosols influence the amount and location of rainfall and water. They also warm or cool the air by scattering and absorbing sunlight. Their presence affects the amount photosynthetic light and agricultural production. And when air pollution gets thick, these same particles reduce the quality of the air we breathe and the health of all living organisms.
In light of these important impacts on climate, weather, and air quality, scientists and policy-makers recognize the need to measure and monitor the distribution and evolution of aerosols. While there are a number of key aerosol properties to monitor, a report from the World Meteorological Organization (WMO) Global Atmospheric Watch (GAW) stated, “In view of these objectives the present observations of the vertical distribution of aerosols are far from adequate.” One motivation for more and better aerosol profiles is the impact of long-range (even intercontinental) transport of pollution, which primarily occurs at elevated layers in the atmosphere.
Aerosols are among the most important pollutants and understanding transport of pollutants in elevated layers followed by downward mixing into the surface layer is essential for air quality forecasts. High quality aerosol profiles can also reveal key atmospheric structures like boundary layer height and its evolution. Aerosols are excellent tracers for gas phase pollutants, and direct observation of plumes from major events such as forest fires, dust storms, and volcanic eruptions require vertically resolved measurements at altitude. Most effects of aerosols on climate, such as scattering and absorption of sunlight and their effects on clouds, require knowing their vertical distribution trends.
Based on the same principle as radar, but using optical rather than radio wavelengths, LIDAR provides a real-time visual display of the aerosols and clouds along any path. LIDAR is becoming a standard tool for measuring aerosol trends, and informing improved weather and air quality forecast.
Sigma Space Corporation builds advanced LIDAR systems for space, aircraft, and surface applications. Since 2004 under license from NASA, we have made the surface-based Micro Pulse LIDAR (MPL), a sophisticated yet easy-to-use laser remote-sensing system. It provides continuous, unattended monitoring of aerosol and cloud profiles helping to meet the WMO challenge. And recently, we have created the ultimate portable “plug and play” LIDAR, the MiniMPL, to keep us all looking up!