eprintid: 23004
rev_number: 15
eprint_status: archive
userid: 3147
dir: disk0/00/02/30/04
datestamp: 2017-06-13 08:23:24
lastmod: 2017-06-28 10:03:28
status_changed: 2017-06-13 08:23:24
type: doctoralThesis
metadata_visibility: show
creators_name: Scalone, Lisa
title: Retrieval of Cirrus Optical Properties in the near-IR
spectral range within the NASA ATTREX Project
subjects: ddc-530
divisions: i-130500
adv_faculty: af-13
cterms_swd: Cirrus Clouds in the Tropical Tropopause Layer
cterms_swd: Differential Optical Absorption Spectroscopy in the near-IR
cterms_swd: Cirrus ice particles optical properties
abstract: In this work we propose a new method based on a near-IR ([900-1700]nm) full spectral retrieval to infer the optical properties of ice particles forming cirrus clouds.
The quasi in situ near-IR spectroscopic measurements were collected by the mini-DOAS instrument (S/N~300) on board the NASA Global Hawk within a critical region for climate forcing, i.e. the tropical tropopause layer (TTL). The theoretical model is set up using a Monte Carlo radiative transfer model for spectral radiance simulations (1% relative error) and a Mie scattering code to calculate the optical properties (~0.0001-0.00001
relative errors). The ice particles are described as mass equivalent spheres and they are treated as a statistical ensemble by making use of two particle size distributions, both parameterized in terms of the ice water contents (IWCs). The novel method is applied to one flight segment where a cirrus cloud over the eastern Pacific TTL was probed during the convective season (NH winter). The cloud optical depths (ODs) are retrieved using the oxygen absorption band at 1270 nm, while the IWCs are inferred from the ice absorption band (1490 nm). The results are compared and discussed with the simultaneous observations of the Cloud Physics Lidar (CPL) and in situ measurements
of Hawkeye, NOAA Water, UCATS and DLH. Together, they provide relevant information concerning the microphysics of cirrus within the TTL. Tropical cirrus clouds are
extremely important for the global radiative net budget (greenhouse vs. albedo effects), since they exert a direct impact on the TTL and on the lower stratosphere in a changing climate. The new method proved to be a powerful tool for cirrus optical properties retrieval. The thresholds for the inferred results are 0.01 for ODs (3.2% relative error) and 0.001 [g/m^3] for the total IWCs (3.8% relative error).
date: 2017
id_scheme: DOI
id_number: 10.11588/heidok.00023004
ppn_swb: 1659230551
own_urn: urn:nbn:de:bsz:16-heidok-230042
date_accepted: 2017-05-17
advisor: HASH(0x55a9a6657610)
language: eng
bibsort: SCALONELISRETRIEVALO2017
full_text_status: public
citation:   Scalone, Lisa  (2017) Retrieval of Cirrus Optical Properties in the near-IR spectral range within the NASA ATTREX Project.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/23004/1/all.pdf