AO2 and Medusa on ATom Jonathan Bent, NCAR Earth Observing Laboratory Instrument Team: Britton Stephens (NCAR), Jonathan Bent (NCAR), Ralph Keeling (Scripps), Andrew Watt (NCAR), Steve Shertz (NCAR) Additional contributions from: HIPPO Science Team, NCAR RAF Staff, Elliot Atlas (RSMAS), Sara Mikaloff-Fletcher (NIWA), Prabir Patra (JAMSTEC), Ivan Lima, Scott Doney (WHOI), Matt Long (NCAR), Olivier Aumont (IPSL), Keith Rodgers (Princeton), John Dunne, Anand Gnanadesikan (GFDL),

Structure -Instrument description -General, ATom-relevant Scientific Goals -HIPPO data, New Science -How ATom can improve our goals

NCAR Airborne Oxygen Instrument (AO2) in situ measurement of O 2 /N 2 by vacuum ultraviolet absorption CO 2 by NDIR for dilution correction active P, T, flow control Precision to sec switching; 40 min Cal frequency Wyoming King Air ACME-07, and the NSF/NCAR GV during START-08, and HIPPO 1-5, planned for ARISTO and ORCAS Measurements at 5-sec frequency have precisions of ± 2 per meg O 2 /N 2 and 0.5 ppm CO 2 Degraded comparability during HIPPO addressed by adjusting to match Medusa HFE-7500 Fluorinert cryotrap with dry ice

NCAR/Scripps Medusa Flask Sampler 32 whole air samples per flight 1.5 L, 1 atm, cryogenically dried, glass flasks Laboratory analysis of CO 2, O 2 /N 2, Ar/N 2, CO 2 isotopologues ( 13 C, 18 O, and 14 C) Precision and comparability (to WMO scale) for CO 2 are ± 0.1 ppm 1-sigma Precision and comparability (to Scripps O 2 Scale) for O 2 /N 2 are ± 2 per meg NSF/NCAR GV during START-08 and HIPPO1-5, planned for ARISTO and ORCAS

Support of Tier I and II objectives fingerprinting of airmasses (O 2 :CO 2, 14 C) marine boundary layer processes CO 2 intercomparisons Independent objectives: Interhemispheric transport of heat and carbon by the oceans Meridional distribution of terrestrial carbon sinks Seasonal exchange of CO 2 with the extratropical oceans Building on HIPPO: Interannual variability Improving seasonal cycle estimates (2 nd harmonics) Characterizing differences between Atlantic and Pacific

“per meg” Reported atmospheric quantity: Combine to make…

Atmospheric Potential Oxygen APO = O *CO 2 Until HIPPO, limited to surface measurements, limiting utility as a tracer of air-sea exchange in models

Outgassing of APO in summer due to warming and productivity Ingassing in winter in response to ventilation of deep waters; strong blooms in NH summer

Annual APO MeansSeasonal APO Amplitudes Annual mean value Higher in SH ~15 per meg Mid Lats. Motivated 1) Resplandy Paper Seasonal Amps Greater at Higher Lats, motivated 2) curtain average approach

B. Stephens, manuscript in prep, 2015 L. Replandy, submitted to GBC, PW Asymmetry 1) Models underestimate Northward heat transport

2) Southern Ocean Curtain Averages J. Bent, Dissertation, 2014 manuscript in prep, S, up to 300 mb

Anchorage (HIPPO1 RF03) Chukchi Sea Bloom (HIPPO4 RF02) (AWAS data) ATom- relevant Products

Atmospheric O 2, CO 2, and Ar Measurement Challenges Fractionation Permeation effects Surface effects CO 2 and H 2 O dilution Cylinder stability Cabin air Plans before ATom I Laboratory work to improve upon AO2 noise, humidity effects, and biases AO2 and Medusa will fly on the NSF/NCAR C130 during the ARISTO instrument test campaign (Sep 2015) AO2 and Medusa will fly on the NSF/NCAR GV during the ORCAS campaign (Jan/Feb 2016). Possibly running a Picarro instead of LiCor

ATom Discussion Points Inlet contamination (venting, leaks, conduits for BL air) Who’s using HIMIL? Dry ice (5 kg / instrument / flight) Shipping/receiving support at Kona and Azores Flask analysis schedule / data delivery Isotopes and ATom 2-4 not yet funded Fluorinert HFE-7500 in cabin MW: 414

to be submitted to GBC, 2015 HIPPO Constraint Northward heat transport necessary to explain the observed APO deficit = PW

January, 2009 per meg – MLO trend

August, 2011 per meg – MLO trend

from single harmonic fits to binned and detrended observations

Mid-latitude uptake

per meg from single harmonic fits to binned and detrended observations Seasonal APO cycles can constrain net marine productivity (seasonal net outgassing or SNO) and air-sea gas exchange rates

Jan-Apr Jun-Aug Sep-Nov

Tohjima et al., GBC, 2012

O 2 in urban pollution studies and emission verification 0.0Cement Production ± 0.07Gas Flaring ± 0.04Natural Gas ± 0.03Liquid Fuel ± 0.03Coal Oxidative Ratios for CO 2 Sources [R. Keeling, 1995] Mexico Expected ratio = mol O 2 :mol CO 2 Expected ratio = mol O 2 :mol CO 2 People’s Republic of China Expected ratio = mol O 2 :mol CO 2 United States of America [from Marland, Boden, and Andres,

NCAR Airborne Oxygen Instrument (AO2) Vacuum ultraviolet absorption technique Xe lamp (147 nm) and CsI detector Adapted from shipboard design (Stephens et al., 2003) Active pressure and flow control to Switches every 2.5 seconds between sample and WT gas 5-second 1-sigma precision of ± 2 per meg Factor of 2-5 motion degradation is correctable O 2 sensor Flow control:

Pollution plume over San Juan Generating Station, NM

Ratio fit to just plume (-1.18) consistent with coal burning (residual noise from motion effects and timing issues, work ongoing)