The influence of typhoons on atmospheric composition deduced from IAGOS measurements over Taipei

Abstract

Abstract. The research infrastructure IAGOS (In-Service Aircraft for a Global Observing System) equips commercial aircraft with instruments to monitor the composition of the atmosphere during flights around the world. In this article, we use data from two China Airlines aircraft based in Taipei (Taiwan) which provided daily measurements of ozone, carbon monoxide and water vapour throughout the summer of 2016. We present time series, from the surface to the upper troposphere, of ozone, carbon monoxide and relative humidity near Taipei, focusing on periods influenced by the passage of typhoons. We examine landing and take-off profiles in the vicinity of tropical cyclones using ERA-5 reanalyses to elucidate the origin of the anomalies in the vertical distribution of these chemical species. Results indicate a high ozone content in the upper- to middle-troposphere track of the storms. The high ozone mixing ratios are generally correlated with potential vorticity and anti-correlated with relative humidity, suggesting stratospheric origin. These results suggest that tropical cyclones participate in transporting air from the stratosphere to troposphere and that such transport could be a regular feature of typhoons. After the typhoons passed Taiwan, the tropospheric column was filled with substantially lower ozone mixing ratios due to the rapid uplift of marine boundary layer air. At the same time, the relative humidity increased, and carbon monoxide mixing ratios fell. Locally, therefore, the passage of typhoons has a positive effect on air quality at the surface, cleansing the atmosphere and reducing the mixing ratios of pollutants such as CO and O3.

A Comparative Study to Reveal the Influence of Typhoons on the Transport, Production and Accumulation of O<sub>3</sub> in the Pearl River Delta, China

“…Moreover, these areas at 850 and 700 hPa generally featured higher O3 mixing ratios as well as lower RH (Fig. S6) than others, which is a sign of possible direct downward O3 transport (Roux et al, 2020;Wang et al, 2020). This part of O3 can notably aggravate near-ground O3 pollution in the PRD.…”

Measurement report: In situ observations of deep convection without lightning during the tropical cyclone Florence 2018

“…They additionally detected enhanced NO concentrations in the eye wall area and suggested lightning as a source based on observations reported by Davis et al (1996). Roux et al (2020) found the convective uplift of boundary layer air as well as the inflow of lower stratospheric air to the upper troposphere based on measurements of CO, O 3 and H 2 O during aircraft typhoon observations over Taipei in 2016. In contrast, studies of lightning activity within convective systems over the ocean and in tropical cyclones are predominantly based on satellite data and ground-based observations from the WWLLN (University of Washington, 2020; Abreu et al, 2010;Bürgesser, 2017;Hutchins et al, 2012b;Bucsela et al, 2019) Generally, data from in situ chemical measurements in the upper troposphere are sparse, and to our knowledge, the in situ aircraft observation of deep convection in tropical cyclones accompanied by and in the absence of lightning depending on the stage of development has not been reported before.…”

“…O 3 mixing ratios were analyzed by UV absorption and chemiluminescence with the FAIRO instrument (chemiluminescence data with a total uncertainty of 2.5 %; Zahn et al, 2012). CO was measured via quantum cascade laser absorption spectroscopy with an uncertainty of 4.3 % (Schiller et al, 2008). H 2 O 2 mixing ratios were measured via dualenzyme detection (modified Aero-Laser AL2021, Garmisch-Partenkirchen, Germany) with a total measurement uncertainty of 9 % and a detection limit of 15 ppt v (Hottmann et al, 2020).…”

Positive and negative influences of landfalling typhoons on tropospheric ozone over southern China

“…Therefore, they can potentially perturbate the structure and chemical compositions in the tropopause region, and promote stratospheretroposphere exchanges (STEs). For example, several studies show that typhoons can induce the downward intrusions of ozonerich air (Jiang et al, 2015;Das et al, 2016;Li et al, 2018;Roux et al, 2020). Such intrusions can even reach the ABL and deteriorate air quality there, as in the case of Typhoon Hagibis over southeastern coast of China reported by Jiang et al (2015).…”

“…Concerning the occurrences of ozone episodes and the spatiotemporal distribution and property of typhoons, Huang et al (2006) found that when a typhoon is about 700-1000 km from the PRD, the region is already controlled by large-scale subsidence of typhoon and suffers high ozone. Roux et al (2020) stated that typhoons at distances of 500-1000 km offshore provide a favourable environment for active photochemical reactions and hence high ozone episodes. It is also documented that surface ozone concentrations increase over southwestern Taiwan 2 to 4 days before the passage of typhoons (Hung and Lo, 2015).…”