The Provenance of Sulfur that Becomes Non-Seasalt Sulfate (NSS) Barry J Huebert, Rebecca M Simpson, Steven G Howell, and Byron W Blomquist Univ Hawaii-Dept Oceanography, Honolulu, HI Abstract: As a part of the Pacific Atmospheric Sulfur Experiment (PASE), we measured sulfur gases and aerosol chemistry (vs size) from the NCAR C-130 near Christmas Island (within an area roughly covering ° W, 0-2.5° N). Monthly (project) average concentrations in the Mixed Layer (ML, the lowest layer) and Buffer Layer (BuL, a more stable layer atop the ML, with clouds) are used to evaluate the formation, loss, and exchange rates for DMS, SO 2, and NSS in each layer and the entire MBL (= ML + BuL). We evaluate entrainment, divergence, vertical mixing, chemical formation and loss for each to make a self-consistent budget of oxidized sulfur in the remote marine atmosphere. We find that long-range transport of sulfur from continental sources can be larger than the sulfur source from biogenic dimethyl sulfide, DMS. DMS does not appear to control either the number of NSS particles (Quinn & Bates, 2011) or NSS mass. Conclusions In the Remote Equatorial Pacific, 10,000 km from the nearest non-marine sulfur source, LRT (Long Range Transport) and Entrainment of SO 2 is an SO 2 source comparable to DMS oxidation. SO 2 is consumed and NSS is produced in the BuL, presumably in cloud. Entrainment brings SO 2 and NSS from LRT into the MBL. Simpson et al. show that these distant sources can supply as much NSS as DMS does. DMS and SO 2 vs Altitude during the Pacific Atmospheric Sulfur Experiment (PASE) Points are 10 sec averages of APIMS-ILS data Lines are 200 m altitude bin averages over the entire program From fourteen C-130 flights; 8 August – 7 Sept 2007 [CO] > 63 ppbv (red) or [CO] < 63 ppbv (blue) FT, Free Trop ML, Mixed Layer BuL, Buffer Layer Sulfur DioxideDimethyl Sulfide Eyeballed Insights about DMS [DMS] ML is large (~75 pptv) and relatively constant with altitude Clearly the only source of DMS is, in the ML (surface emission) [DMS] FT ~ 0, so the FT is not a source. Small concentrations at the bottom of the FT are the result of averaging over many different inversion heights. [DMS] BuL mixes more or less linearly from [DMS] ML to [DMS] FT Sensible This ideal profile is evident in the monthly data, but not daily. On the scale of a month, the ML really is well-mixed. Vertical and km-scale horizontal heterogeneity average out. The range of [DMS] on any one flight leg is almost as large as its variability for the entire month Individual points were during soundings (altitude changes) Pancake-smears show the variation during constant-altitude legs. Each km flight leg encountered a wide range of conditions (clouds, sloping inversions, productive patches, etc.) Eyeballed Insights about SO 2 [SO 2 ] ML is ~50 pptv and relatively constant with altitude Clearly there must be a source of SO 2 in the ML. (DMS + OH) [SO 2 ] FT ≠ 0, so the FT is also a significant SO 2 source. Entrainment of FT air must bring FT SO 2 into the BuL. [SO 2 ] BuL is smaller than [SO 2 ] ML and less than or equal to [SO 2 ] FT The BuL must contain a sink for SO 2 (clouds) On this time scale, the ML really is well-mixed. The range of [SO 2 ] on any one flight leg is almost as large as its variability for the entire month Pancake-smears show the variation during constant-altitude legs. Each km flight leg encountered a wide range of conditions (clouds, sloping inversions, productive patches, etc.) A Personal Note I can no longer hear worth a damn; too many jet engines and table saws I am most likely to pick your voice out of all the others in the room if you turn your face to me while talking. Thanks, Barry This is dedicated to the memory of Alan Bandy, who spent four decades developing the analytical methods that made this work possible. Eyeballed Insights about NSS Unlike the gases, there is no 10 sec NSS data MBL NSS data was derived from 30 min Micro-Orifice Impactor samples and IC analysis [NSS] ML is large (~150 pptx) and relatively constant with altitude … throughout the entire MBL [NSS] BuL is virtually identical to[NSS] ML Much of the NSS production must occur in the BuL (in clouds) [NSS] FT ~ 0.3 [NSS] BuL Entrainment would have reduced [NSS] BuL if there had been no BuL NSS production. NSS Production and Dilution must roughly balance in the BuL. Entrainment of FT NSS is a significant NSS source to the MBL Subsidence pushes even dilute FT substances into the MBL. Don’t trust your eyeballs that much? Be on the lookout for “R. M. Simpson et al., Sources of tropical non- sea salt sulfate derived from a month-scale sulfur budget and PASE observations of DMS, SO 2, and NSS” … in which all the relevant process rates are evaluated and quantified. Coming soon to a journal near you. Rebecca Simpson A Personal Note I can no longer hear worth a damn; too many jet engines and table saws I am most likely to pick your voice out of all the others in the room if you turn your face to me while talking. Thanks, Barry A Personal Note I can no longer hear worth a damn; too many jets and table saws I am most likely to pick your voice out of all the others in the room if you turn your face to me while talking. Thanks, Barry Non-Seasalt Sulfate, NSS Project-average NSS from PASE MOI, PASE particle volume, ACE-1 impactor, and PEM- Tropics filters vs Altitude