Twenty Years of Global Stratospheric Fluorine Inventories From Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) Measurements

Abstract

We present fluorine inventories calculated for twenty years (2004–2023) and five latitude bands (82°–60°N, 60°–30°N, 30°N–30°S, 30°–60°S, and 60°–82°S) at altitudes from the surface up to 55 km. The inventories were calculated using the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) version 5.2 retrievals of the volume mixing ratios (VMRs) of 15 fluorine-containing species. Of these 15 species, 3 are product gases: (Formula presented.), (Formula presented.), (Formula presented.), and 12 are source gases: (Formula presented.), PFC-14 ((Formula presented.)), CFC-11 ((Formula presented.)), CFC-12 ((Formula presented.)), CFC-113 ((Formula presented.)), HCFC-22 ((Formula presented.)), HCFC-141b ((Formula presented.)), HCFC-142b ((Formula presented.)), HFC-23 ((Formula presented.)), HFC-32 ((Formula presented.)), HFC-125 ((Formula presented.)), and HFC-134a ((Formula presented.)). As necessary, ACE-FTS data were supplemented with data from the TOMCAT 3-D chemical transport model and ground-based measurements from the National Oceanic and Atmospheric Administration (NOAA) and the Advanced Global Atmospheric Gases Experiment (AGAGE). The total fluorine ((Formula presented.)) profiles are dominated by source gas contributions in the troposphere and lower stratosphere up to 35 km in the tropics (30°N–30°S), 30 km in midlatitudes (60°–30°N/30°–60°S) and 24 km near the poles (82°–60°N/60°–82°S). In this atmospheric region, the primary contributions come from CFCs, HCFCs, carbon tetrafluoride ((Formula presented.)), and increasingly in recent years HFCs. Above these altitudes (Formula presented.) increasingly dominates the (Formula presented.) profile reaching as much as 79% of (Formula presented.) at 55 km. The 2004–2023 time series of the mean (Formula presented.) inventories shows a global increase of 48.9 (Formula presented.) 0.7 ppt/year or 1.68 (Formula presented.) 0.02%/year resulting in a mean (Formula presented.) approaching 3.5 ppb in 2023.