Preprints
https://doi.org/10.5194/egusphere-2023-1023
https://doi.org/10.5194/egusphere-2023-1023
12 Jun 2023
 | 12 Jun 2023

Measurement Report: The Palau Atmospheric Observatory and its Ozonesonde Record - Continuous Monitoring of Tropospheric Composition and Dynamics in the Tropical West Pacific

Katrin Müller, Jordis S. Tradowsky, Peter von der Gathen, Christoph Ritter, Sharon Patris, Justus Notholt, and Markus Rex

Abstract. The Tropical West Pacific is recognized as an important region for stratosphere-troposphere exchange, but has been a measurement gap in the global ozone sounding network. The Palau Atmospheric Observatory (PAO) was established to study the atmospheric composition above the remote Tropical West Pacific with a comprehensive instrumental setup. Since 2016, two laboratory containers in Palau host an Fourier-transform infrared spectrometer, a lidar (micro lidar until 2016, cloud and aerosol lidar from 2018), a Pandora 2S photometer and laboratory space for weather balloon soundings with ozone-, water-vapor-, aerosol- and radiosondes. In this analysis, we focus on the continuous, fortnightly ozone sounding program with Electrochemical Concentration Cell (ECC) ozone sondes.

The aim of this study is to introduce the PAO and its research potential, present the first observation of the typical seasonal cycle of tropospheric ozone in the Tropical West Pacific based on a multiannual record of in situ observations, and investigate major drivers of variability and seasonal variation from 01/2016 until 12/2021 related to the large scale atmospheric circulation. We present the PAO ozone (O3) volume mixing ratios (VMR) and relative humidity (RH) time series complemented by other observations.

The site is exposed to year-round high convective activity reflected in dominating low O3 VMR and high RH. In 2016, the impact of the strong El Niño is evident as a particularly dry, ozone-rich episode. The main modulator of annual tropospheric O3 variability is identified as the movement of the Intertropical Convergence Zone (ITCZ), with lowest O3 VMR in the free troposphere during the ITCZ position north of Palau. An analysis of the relation of O3 and RH for the PAO and selected sites from the Southern Hemispheric ADditional OZonesondes (SHADOZ) network reveals three different regimes. Palau’s O3/RH distribution resembles the one in Fiji, Java and American Samoa, but is unique in its seasonality and its comparably narrow Gaussian distribution around low O3 VMR and the evenly distributed RH. A previously found bimodal distribution of O3 VMR and RH could not be seen in the Palau record.

Due to its unique remote location, Palau is an ideal atmospheric background site to detect changes in air dynamics imprinted on the chemical composition of the tropospheric column. The efforts to establish, run and maintain the PAO have succeeded to fill an observational gap in the remote Tropical West Pacific and give good prospects for ongoing operations. The ECC sonde record will be integrated into the SHADOZ database in the near future.

Journal article(s) based on this preprint

21 Feb 2024
Measurement report: The Palau Atmospheric Observatory and its ozonesonde record – continuous monitoring of tropospheric composition and dynamics in the tropical western Pacific
Katrin Müller, Jordis S. Tradowsky, Peter von der Gathen, Christoph Ritter, Sharon Patris, Justus Notholt, and Markus Rex
Atmos. Chem. Phys., 24, 2169–2193, https://doi.org/10.5194/acp-24-2169-2024,https://doi.org/10.5194/acp-24-2169-2024, 2024
Short summary
Katrin Müller, Jordis S. Tradowsky, Peter von der Gathen, Christoph Ritter, Sharon Patris, Justus Notholt, and Markus Rex

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1023', Anonymous Referee #1, 10 Jul 2023
  • RC2: 'Comment on egusphere-2023-1023', Anonymous Referee #2, 14 Jul 2023
  • AC1: 'AC- Comment on egusphere-2023-1023', Katrin Müller, 25 Oct 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1023', Anonymous Referee #1, 10 Jul 2023
  • RC2: 'Comment on egusphere-2023-1023', Anonymous Referee #2, 14 Jul 2023
  • AC1: 'AC- Comment on egusphere-2023-1023', Katrin Müller, 25 Oct 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Katrin Müller on behalf of the Authors (25 Oct 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (01 Nov 2023) by Jerome Brioude
AR by Katrin Müller on behalf of the Authors (21 Nov 2023)  Manuscript 

Journal article(s) based on this preprint

21 Feb 2024
Measurement report: The Palau Atmospheric Observatory and its ozonesonde record – continuous monitoring of tropospheric composition and dynamics in the tropical western Pacific
Katrin Müller, Jordis S. Tradowsky, Peter von der Gathen, Christoph Ritter, Sharon Patris, Justus Notholt, and Markus Rex
Atmos. Chem. Phys., 24, 2169–2193, https://doi.org/10.5194/acp-24-2169-2024,https://doi.org/10.5194/acp-24-2169-2024, 2024
Short summary
Katrin Müller, Jordis S. Tradowsky, Peter von der Gathen, Christoph Ritter, Sharon Patris, Justus Notholt, and Markus Rex

Data sets

Ozone sonde and radio sonde data record Palau Atmospheric Observatory 2016-2021 (V1.0) Katrin Müller, Jürgen Graeser, Sharon Patris, Ingo Beninga, Wilfried Ruhe, Gerda Ucharm, and Jordis Tradowsky https://doi.org/10.5281/zenodo.6920648

Katrin Müller, Jordis S. Tradowsky, Peter von der Gathen, Christoph Ritter, Sharon Patris, Justus Notholt, and Markus Rex

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Latest update: 21 Feb 2024
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Short summary
The Palau Atmospheric Observatory is introduced as an ideal site to detect changes in atmospheric composition and dynamics above the remote Tropical West Pacific. We focus on the ozone sounding program from 2016–2021, including El Nino 2016. The year-round high convective activity is reflected in dominant low tropospheric ozone and high relative humidity. The seasonal distribution of both constituents is unique compared to other tropical sites and modulated by the Intertropical Convergence Zone.