Determining stages of cirrus evolution: a cloud classification scheme

Abstract

Abstract. Cirrus clouds impose high uncertainties on climate prediction, as knowledge on important processes is still incomplete. For instance it remains unclear how cloud microphysical and radiative properties change as the cirrus evolves. Recent studies classify cirrus clouds into categories including in situ, orographic, convective and liquid origin clouds and investigate their specific impact. Following this line, we present a novel scheme for the classification of cirrus clouds that addresses the need to determine specific stages of cirrus evolution. Our classification scheme is based on airborne Differential Absorption and High Spectral Resolution Lidar measurements of atmospheric water vapor, aerosol depolarization, and backscatter, together with model temperature fields and simplified parameterizations of freezing onset conditions. It identifies regions of supersaturation with respect to ice (ice-supersaturated regions, ISSRs), heterogeneous and homogeneous nucleation, depositional growth, and ice sublimation and sedimentation with high spatial resolution. Thus, all relevant stages of cirrus evolution can be classified and characterized. In a case study of a gravity leewave-influenced cirrus cloud, encountered during the ML-CIRRUS flight campaign, the applicability of our classification is demonstrated. Revealing the structure of cirrus clouds, this valuable tool might help to examine the influence of evolution stages on the cloud's net radiative effect and to investigate the specific variability of optical and microphysical cloud properties in upcoming research.

Mixing at the extratropical tropopause as characterized by collocated airborne H2O and O3 lidar observations

“…(e.g., Schäfler et al, 2010;Kiemle et al, 2011), cloud-microphysics (Urbanek et al, 2017) to UTLS investigations (Trickl et al, 2016). In 2012, the system was extended by an optional O3-DIAL capability (Fix et al, 2019) to be able to measure collocated profiles of O3 and H2O.…”

Intercomparison of midlatitude tropospheric and lower-stratospheric water vapor measurements and comparison to ECMWF humidity data

“…Since this paper focusses on the intercomparison of the in situ water vapor measurements during ML-CIRRUS, only those instruments will be described here in detail. A full list of instruments, their descriptions and references can be found in Voigt et al (2017).…”

“…3.3) is also part of BAHAMAS. Cloud detection was done using data from the Cloud and Aerosol Spectrometer with Detection of Polarization (CAS-DPOL), which was mounted under the wing of HALO (Baumgardner et al, 2001;Voigt et al, 2017). The cloud probe measures particles in a size range between 0.5 and 50 µm and is thus sensitive to natural cirrus as well as contrail ice particles.…”

Measurement Characteristics of an airborne Microwave Temperature Profiler (MTP)

“…Gamblin et al, 2006;Popp et al, 2006;Schwarz et al, 2008), and assist the study of cloud physics (e.g. Corti et al, 2008;Jensen et al, 2010;Schumann et al, 2017;Urbanek et al, 2017), and dynamics in the atmosphere (e.g. Tuck et al, 1997Tuck et al, , 2003Dörnbrack et al, 2002;Sitnikova et al, 2009).…”