Planning, implementation, and first results of the Tropical Composition, Cloud and Climate Coupling Experiment (TC4)

Abstract

The Tropical Composition, Cloud and Climate Coupling Experiment (TC4), was based in Costa Rica and Panama during July and August 2007. The NASA ER‐2, DC‐8, and WB‐57F aircraft flew 26 science flights during TC4. The ER‐2 employed 11 instruments as a remote sampling platform and satellite surrogate. The WB‐57F used 25 instruments for in situ chemical and microphysical sampling in the tropical tropopause layer (TTL). The DC‐8 used 25 instruments to sample boundary layer properties, as well as the radiation, chemistry, and microphysics of the TTL. TC4 also had numerous sonde launches, two ground‐based radars, and a ground‐based chemical and microphysical sampling site. The major goal of TC4 was to better understand the role that the TTL plays in the Earth's climate and atmospheric chemistry by combining in situ and remotely sensed data from the ground, balloons, and aircraft with data from NASA satellites. Significant progress was made in understanding the microphysical and radiative properties of anvils and thin cirrus. Numerous measurements were made of the humidity and chemistry of the tropical atmosphere from the boundary layer to the lower stratosphere. Insight was also gained into convective transport between the ground and the TTL, and into transport mechanisms across the TTL. New methods were refined and extended to all the NASA aircraft for real‐time location relative to meteorological features. The ability to change flight patterns in response to aircraft observations relayed to the ground allowed the three aircraft to target phenomena of interest in an efficient, well‐coordinated manner.

Improved rain rate and drop size retrievals from airborne Doppler radar

“…The observations are from NASA's high-altitude ER-2 aircraft during the TC4 experiment conducted over the tropical eastern Pacific in July and August 2007 (Toon et al, 2010). ER-2 flies above the tropopause at an altitude of 20 km with a cruise speed of around 200 m s −1 .…”

“…Three visible channels are combined to create composite images of the case studies. Due to a failure in the MAS instrument, the MASTER instrument flew aboard ER-2 as a replacement after 29 July 2007 (Toon et al, 2010); the channels used in this study are common to both instruments.…”

“…In this study we use a variational retrieval methodology developed for EarthCARE to investigate improved estimates of rain rate by exploiting mean Doppler velocity measurements to retrieve drop size and drop number concentration parameters of the DSD. NASA's high-altitude ER-2 aircraft provides an ideal platform for testing satellite instruments and retrievals; we use ER-2 measurements taken during the Tropical Composition, Clouds and Climate Coupling field campaign (TC4) off Costa Rica and Panama in 2007 (Toon et al, 2010). A second 9.6 GHz Doppler radar aboard ER-2 provides independent measurements at a less attenuated wavelength, against which the retrievals are evaluated.…”

Ice hydrometeor profile retrieval algorithm for high-frequency microwave radiometers: application to the CoSSIR instrument during TC4

“…The retrieval algorithm is tested with data from the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR, Evans et al, 2005) flown on the NASA ER-2 aircraft in July and August 2007 during the Tropical Composition, Cloud and Climate Coupling (TC4) experiment (Toon et al, 2010). CoSSIR measured brightness temperatures in 11 double sideband channels around 183.3, 220.0, 380.2, 640.0 and 873.6 GHz.…”

Potential of remote sensing of cirrus optical thickness by airborne spectral radiance measurements at different sideward viewing angles

“…Airborne campaigns dedicated to visible cirrus, e.g., the Contrail, volcano and Cirrus Experiment (CONCERT, Voigt et al, 2010), Mid-Latitude Cirrus (ML-CIRRUS, Voigt et al (2016)) and tropical cirrus sampled during the Airborne Tropical TRopopause EXperiment (ATTREX) are more frequent (Delanoe et al, 2013;Ehret et al, 2014;Gross et al, 2015;Jensen et al, 2015) and occasionally include observations of SVC. Further international airborne missions like the Tropical Composition, Cloud and Climate Coupling (TC4) (Toon et al, 2010) and the Cirrus Regional Study of Tropical Anvils and Cirrus Layers -Florida Area Cirrus Experiment (CRYSTAL-FACE) mission were conducted, trying to fill the knowledge gap about the formation process and physical properties of tropical cirrus (Jensen et al, 2015).…”