First characterization and validation of FORLI-HNO 3 vertical profiles retrieved from IASI/Metop

• Published in: Atmospheric Measurement Techniques
• Main Authors: Ronsmans, Gaétane, Langerock, Bavo, Wespes, Catherine, Hannigan, James, Hase, Frank, Kerzenmacher, Tobias, Mahieu, Emmanuel, Schneider, Matthias, Smale, Dan, Hurtmans, Daniel, de Mazière, Martine, Clerbaux, Cathy, Coheur, Pierre-François
• Other Authors: Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Atmospheric Chemistry Observations and Modeling Laboratory (ACOML), National Center for Atmospheric Research Boulder (NCAR), Institute for Meteorology and Climate Research (IMK), Karlsruhe Institute of Technology (KIT), Institut d'Astrophysique et de Géophysique Liège, Université de Liège, National Institute of Water and Atmospheric Research Lauder (NIWA), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; Kiruna; Arrival Heights
• Online Access: https://insu.hal.science/insu-01384959; https://insu.hal.science/insu-01384959/document; https://insu.hal.science/insu-01384959/file/amt-9-4783-2016.pdf; https://doi.org/10.5194/amt-9-4783-2016

International audience Knowing the spatial and seasonal distributions of nitric acid (HNO 3 ) around the globe is of great interest and allows us to comprehend the processes regulating stratospheric ozone, especially in the polar regions. Due to its unprecedented spatial and temporal sampling, the nadir-viewing Infrared Atmospheric Sounding Interferome-ter (IASI) is capable of sounding the atmosphere twice a day globally, with good spectral resolution and low noise. With the Fast Optimal Retrievals on Layers for IASI (FORLI) algorithm , we are retrieving, in near real time, columns as well as vertical profiles of several atmospheric species, among which is HNO 3 . We present in this paper the first characterization of the FORLI-HNO 3 profile products, in terms of vertical sensitivity and error budgets. We show that the sensitivity of IASI to HNO 3 is highest in the lower stratosphere (10–20 km), where the largest amounts of HNO 3 are found, but that the vertical sensitivity of IASI only allows one level of information on the profile (degrees of freedom for signal, DOFS; ∼ 1). The sensitivity near the surface is negligible in most cases, and for this reason, a partial column (5–35 km) is used for the analyses. Both vertical profiles and partial columns are compared to FTIR ground-based measurements from the Network for the Detection of Atmospheric Composition Change (NDACC) to characterize the accuracy and precision of the FORLI-HNO 3 product. The profile validation is conducted through the smoothing of the raw FTIR profiles by the IASI averaging kernels and gives good results , with a slight overestimation of IASI measurements in the upper troposphere/lower stratosphere (UTLS) at the six chosen stations (Thule, Kiruna, Jungfraujoch, Izaña, Lauder and Arrival Heights). The validation of the partial columns (5–35 km) is also conclusive with a mean correlation of 0.93 between IASI and the FTIR measurements. An initial survey of the HNO 3 spatial and seasonal variabilities obtained from IASI measurements for a ...