Emission estimates of HCFCs and HFCs in California from the 2010 CalNex study

Abstract

The CalNex 2010 (California Research at the Nexus of Air Quality and Climate Change) study was designed to evaluate the chemical composition of air masses over key source regions in California. During May to June 2010, air samples were collected on board a National Oceanic and Atmospheric Administration (NOAA) WP‐3D aircraft over the South Coast Air Basin of California (SoCAB) and the Central Valley (CV). This paper analyzes six effective greenhouse gases—chlorodifluoromethane (HCFC‐22), 1,1‐dichloro‐1‐fluoroethane (HCFC‐141b), 1‐chloro‐1,1‐difluoroethane (HCFC‐142b), 2‐chloro‐1,1,1,2‐tetrafluoroethane (HCFC‐124), 1,1,1,2‐tetrafluoroethane (HFC‐134a), and 1,1‐difluoroethane (HFC‐152a)—providing the most comprehensive characterization of chlorofluorocarbon (CFC) replacement compound emissions in California. Concentrations of measured HCFCs and HFCs are enhanced greatly throughout the SoCAB and CV, with highest levels observed in the SoCAB: 310 ± 92 pptv for HCFC‐22, 30.7 ± 18.6 pptv for HCFC‐141b, 22.9 ± 2.0 pptv for HCFC‐142b, 4.86 ± 2.56 pptv for HCFC‐124, 109 ± 46.4 pptv for HFC‐134a, and 91.2 ± 63.9 pptv for HFC‐152a. Annual emission rates are estimated for all six compounds in the SoCAB using the measured halocarbon to carbon monoxide (CO) mixing ratios and CO emissions inventories. Emission rates of 3.05 ± 0.70 Gg for HCFC‐22, 0.27 ± 0.07 Gg for HCFC‐141b, 0.06 ± 0.01 Gg for HCFC‐142b, 0.11 ± 0.03 Gg for HCFC‐124, 1.89 ± 0.43 Gg for HFC‐134a, and 1.94 ± 0.45 Gg for HFC‐152b for the year 2010 are calculated for the SoCAB. These emissions are extrapolated from the SoCAB region to the state of California using population data. Results from this study provide a baseline emission rate that will help future studies determine if HCFC and HFC mitigation strategies are successful.

Deposition and rainwater concentrations of trifluoroacetic acid in the United States from the use of HFO‐1234yf

“…in our scenario, in agreement with the observational estimate for California HFC-134a emissions of 1.18 ± 0.40 × 10 5 mol d −1 in 2010 [Barletta et al, 2013].…”

“…Barletta et al [2011] [Barletta et al, 2013]. The noted differences reflect the uncertainties in the estimation of emission ratios and emissions of HFC-134a and CO.…”

Increase in HFC‐134a emissions in response to the success of the Montreal Protocol

“…To evaluate our posterior HFC‐134a U.S. emissions, we compared model simulations with the independent (i.e., not used as constraints in the inversion) HFC‐134a measurements from two campaigns: ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites, NASA project, [ Barletta et al , ]) and CalNex (California Research at the Nexus of Air Quality and Climate Change, [ Barletta et al , ]). The ARCTAS air samples were obtained on board research flights (DC‐8) that flew over California during June 2008.…”

High-Global Warming Potential F-gas Emissions in California: Comparison of Ambient-Based versus Inventory-Based Emission Estimates, and Implications of Refined Estimates

“…In the SoCAB [Southern California Air Basin], transportation dominates CO emissions (light-duty trucks and passenger vehicles emit about 43% of CO in the SoCAB) ... as a result, CO and halocarbon emissions are relatively well collocated as indicated by the regression analysis. "30 …”

“…−30 For example,Barletta et al, 2013, notes, "Considering that most HCFC and HFC emissions are released from refrigeration and stationary and mobile air conditioning systems, HCFC and HFC emissions will be collocated with CO emissions related to residential and commercial activities and to transportation. In the SoCAB [Southern California Air Basin], transportation dominates CO emissions (light-duty trucks and passenger vehicles emit about 43% of CO in the SoCAB) ... as a result, CO and halocarbon emissions are relatively well collocated as indicated by the regression analysis.…”