English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  Calibration of an airborne HOx instrument using the All Pressure Altitude-based Calibrator for HOx Experimentation (APACHE)

Marno, D., Ernest, C., Hens, K., Javed, U., Klimach, T., Martinez, M., et al. (2020). Calibration of an airborne HOx instrument using the All Pressure Altitude-based Calibrator for HOx Experimentation (APACHE). Atmospheric Measurement Techniques, 13(5), 2711-2731. doi:10.5194/amt-13-2711-2020.

Item is

Basic

show hide
Genre: Journal Article

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Marno, Daniel1, Author              
Ernest, Cheryl2, Author
Hens, Korbinian2, Author              
Javed, Umar1, Author              
Klimach, Thomas3, Author              
Martinez, Monica1, Author              
Rudolf, Markus1, Author              
Lelieveld, Jos1, Author              
Harder, Hartwig1, Author              
Affiliations:
1Atmospheric Chemistry, Max Planck Institute for Chemistry, Max Planck Society, ou_1826285              
2external, ou_persistent22              
3Multiphase Chemistry, Max Planck Institute for Chemistry, Max Planck Society, ou_1826291              

Content

show
hide
Free keywords: -
 Abstract: Laser-induced fluorescence (LIF) is a widely used technique for both laboratory-based and ambient atmospheric chemistry measurements. However, LIF instruments require calibrations in order to translate instrument response into concentrations of chemical species. Calibration of LIF instruments measuring OH and HO2 (HOx) typically involves the photolysis of water vapor by 184.9 nm light, thereby producing quantitative amounts of OH and HO2. For ground-based HOxinstruments, this method of calibration is done at one pressure (typically ambient pressure) at the instrument inlet. However, airborne HOx instruments can experience varying cell pressures, internal residence times, temperatures, and humidity during flight. Therefore, replication of such variances when calibrating in the lab is essential to acquire the appropriate sensitivities. This requirement resulted in the development of the APACHE (All Pressure Altitude-based Calibrator for HOx Experimentation) chamber to characterize the sensitivity of the airborne LIF-FAGE (fluorescence assay by gas expansion) HOx instrument, HORUS, which took part in an intensive airborne campaign, OMO-Asia 2015. It utilizes photolysis of water vapor but has the additional ability to alter the pressure at the nozzle of the HORUS instrument. With APACHE, the HORUS instrument sensitivity towards OH (26.1-7.8 cts s-1 pptv-1 mW-1, ±22.6% 1 σ; cts stands for counts by the detector) and HOx (21.2-8.1 cts s-1 pptv-1 mW(-1), ±22.1% 1 σ) was characterized to the external pressure range at the instrument nozzle of 227-900 mbar. Measurements supported by a computational fluid dynamics model, COMSOL Multiphysics, revealed that, for all pressures explored in this study, APACHE is capable of initializing a homogenous flow and maintaining near-uniform flow speeds across the internal cross section of the chamber. This reduces the uncertainty regarding average exposure times across the mercury (Hg) UV ring lamp. Two different actinometrical approaches characterized the APACHE UV ring lamp flux as 6.37 x 1014(± 1.3 x 1014) photons cm -2 s -1. One approach used the HORUS instrument as a transfer standard in conjunction with a calibrated on-ground calibration system traceable to NIST standards, which characterized the UV ring lamp flux to be 6.9(±1.1) x 10-14 photons cm-2 s-1. The second approach involved measuring ozone production by the UV ring lamp using an ANSYCO O3 41M ozone monitor, which characterized the UV ring lamp flux to be 6.11(±0.8) x 1014 photons cm-2 s-1. Data presented in this study are the first direct calibrations of an airborne HOx instrument, performed in a controlled environment in the lab using APACHE.

Details

show
hide
Language(s):
 Dates: 2020
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: ISI: 000537699800002
DOI: 10.5194/amt-13-2711-2020
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: Atmospheric Measurement Techniques
  Abbreviation : AMT
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Göttingen : European Geosciences Union, Copernicus
Pages: - Volume / Issue: 13 (5) Sequence Number: - Start / End Page: 2711 - 2731 Identifier: ISSN: 1867-1381
CoNE: https://pure.mpg.de/cone/journals/resource/1867-1381