Cloud and Aerosol Research
Aerosols and clouds are being investigated using a variety of remote and in situ measurements combined with theory. This work is leading to a broader understanding of atmospheric particles from the troposphere through the mesosphere, and boasts some exciting new discoveries.
Particles under investigation include
Stratospheric Sulfate Aerosols: These particles consist of H2SO 4-H2O mixtures and are always present at stratospheric altitudes around the globe.
Cirrus: These clouds consist of ice particles and occur globally throughout the year within the upper troposphere.
Polar Stratospheric Clouds (PSCs): These clouds consist of either ice or nitric acid condensates and occur within the stratosphere during winter at polar latitudes in both hemispheres.
Polar Mesospheric Clouds (PMCs): These clouds consist of ice particles and occur near the mesopause (83 km) during polar summer in both hemispheres.
Tropical Nitric Acid Clouds (TNCs): These clouds consist of nitric acid condensates and occur at tropical latitudes throughout the year at altitudes from the upper troposphere to the lower stratosphere.
Cosmic Smoke and Dust: Meteoroids are constantly entering the Earth's atmosphere, and are vaporized in the lower thermosphere/upper mesosphere due to heating during atmospheric entry. The resulting cosmic "smoke" particles accumulate near 85 km altitude globally.
- HALOE observations have demonstrated for the first time, that nitric acid clouds exist near the tropical tropopause [Hervig and McHugh, Geophys. Res. Letters, 29(7) , 10.1029/2001GL014271, 2002]
- Analysis of stratospheric aerosol measurements from SAGE II, HALOE, and in situ optical particle counters [Hervig and Deshler, J. Geophys., Res., 107(D3), 10.1029/2001JD000703, 2002; abstract ]
- Infrared measurements from HALOE have provided the first physical evidence that water ice is the primary component of polar mesospheric clouds (PMCs) [Hervig et al., Geophys. Res. Letters, 28, 971-974, 2001]
- Measurements of polar stratospheric clouds (PSCs) from AVHRR [Hervig et al., J. Geophys. Res., 106, 10,363-10375, 2001]
- A climatology of stratospheric aerosol size distributions from HALOE measurements
- An unusual low latitude display of stratospheric clouds over England, observed by HALOE [Hervig, Geophys. Res. Letters, 26, 1137-1140, 1999].