Jason L. Tackett

Unusually Deep Wintertime Cirrus Clouds Observed over the Alaskan Subarctic

AbstractUnusually deep wintertime cirrus clouds at altitudes exceeding 13.0 km above mean sea level (AMSL) were observed at Fairbanks, Alaska (64.86° N, 147.85° W, 0.300 km AMSL) over a twelve hour period, beginning near 1200 UTC on 1 January 2017. Such elevated cirrus cloud heights are far more typical of warmer latitudes, and in many instances associated with convective outflow, as opposed to early winter over the sub-Arctic on a day featuring barely four hours of local sunlight. In any other context, they could have been confused for polar stratospheric clouds, which are a more common regional/seasonal occurrence approaching such elevated heights. The mechanics of this unique event are documented, including the thermodynamic and synoptic environments that nurtured and sustained cloud formation. The impact of an unusually deep and broad anticyclone over the wintertime Alaskan sub-Arctic is described. Comparisons with climatological datasets illustrate how unusual these events are regionally and seasonal...

The CALIPSO Mission: results and progress

Aerosols and clouds play important roles in Earths climate system but uncertainties over their interactions and their effects on the Earth energy budget limit our understanding of the climate system and our ability to model it. The CALIPSO satellite was developed to provide new capabilities to observe aerosol and cloud from space and to reduce these uncertainties. CALIPSO carries the first polarization-sensitive lidar to fly in space, which has now provided a four-year record of global aerosol and cloud profiles. This paper briefly summarizes the status of the CALIPSO mission, describes some of the results from CALIPSO, and presents highlights of recent improvements in data products.

CALIPSO lidar level 3 aerosol profile product: version 3 algorithmdesign

This paper outlines the methodology behind the CALIPSO Level 3 data product. A simple average is used to aggregate Level 2 profiles, with clear skies assigned zero extinction (rather than being omitted from the average). The quality control system is described at some length, identifying unreliable data by geometrical, statistical, and algorithmic means (e.g. aerosols found in unexpected locations, a maximal uncertainty on extinction, and QC flags, respectively). The spatial and temporal impacts of each filter are presented, demonstrating that these choices alter the final result but in a manner that is expected to be more representative of reality.

Cloud-Aerosol Interactions: Retrieving Aerosol Angstrom Exponents from CALIPSO Measurements of Opaque Water Clouds

Backscatter and extinction from water clouds are well-understood, both theoretically and experimentally, and thus changes to the expected measurement of layer-integrated attenuated backscatter can be used to infer the optical properties of overlying layers. In this paper we offer a first look at a new retrieval technique that uses CALIPSO measurements of opaque water clouds to derive optical depths and Angstrom exponents for overlying aerosol layers.