NOAA Single Particle Soot Photometer (SP2) in ATom Joseph Katich and Joshua Schwarz Humidified-Dual SP2 in DC-8 Rack (anticipated configuration for ATom) Black Carbon (BC) science background and goals in ATom SP2 Status ATom Science Meeting July 2015

BC affects climate Directly: light absorption heats the air or snow/ice on the ground; cools the surface below Indirectly: nucleus for condensation and ice formation “Semi-directly” warming the air and evaporating clouds, changing the thermal structure of the atmosphere So BC affects climate in many ways, but how important are its influences? Bond et al., 2013

How important are Black Carbon Climate impacts? BC alone makes ~ 2/3 of forcing of CO2. BC with co-emitted species produces a very small forcing Large uncertainties. BC is short lived – i.e. largely removed from the atmosphere in just days. Potential to provide “immediate relief” on climate is very intriguing. Bond et al., 2013 What do we need to know more about to reduce the uncertainties? Large Uncertainties!

The Basics Questions How much BC is out there? Where is it? Where does it come from? What are the different microphyscial properties of BC difference sources? How is it removed from the air? Does this depend strongly on internal mixtures? What are its optical properties? How important are coatings to these properties? What are its ice-nucleating properties? ….

HIPPO results tested AeroCom In fact, the work that I’m doing here is focused on extending these results to source regions. 12 AeroCom models are the basis for much of the IPCC estimate of BC forcing. These results point to removal of BC as a major factor in model bias in the remote and at altitude.

J. Schwarz, B. Weinzierl (LMU/DLR) and B. Samset (CICERO) Trans-Atlantic Model/Measurement of BC Analysis (TAMMBA) – Preview of ATom J. Schwarz, B. Weinzierl (LMU/DLR) and B. Samset (CICERO) All of this supports the notion that improving understanding of BC removal will help address some of the large uncertainties associated with BC’s climate forcing. Great. Bt now, what do we need to know to better understand removal? Focused on extending/strengthening previous comparisons into North America, Europe, Africa, and the Arctic. More source regions

Zonal Mixing of BC Average BC MMR from ~8 - 11 km Observations over two-month periods don’t show changes in background BC loads in the UT. Variability from one year to another can be a factor of 10. BC is zonally mixed very well in the UT: can expect similar loads over Pacific and Atlantic Trends between Pacific and Atlantic UT loads likely represent timescales for BC injection/removal. All of this supports the notion that improving understanding of BC removal will help address some of the large uncertainties associated with BC’s climate forcing. Great. Bt now, what do we need to know to better understand removal?

ATom SP2 Goals ATom features relevant to previous SP2 work: Pacific/Atlantic Consistent profiles to 12 km (HIPPO was usually 8 km, rarely 14 km. Higher is better closer to stratosphere boundary conditions) Analysis foci (a priori): Removal from different types of sources that produce BC with different microphysical properties (i.e. Asia vs Africa). Longitudinal variability in each hemisphere – evaluate speculation about global nature of HIPPO results and inferred climate relevance. Resolve timescale for BC removal in upper troposphere. All of this supports the notion that improving understanding of BC removal will help address some of the large uncertainties associated with BC’s climate forcing. Great. Bt now, what do we need to know to better understand removal?

Single Particle Soot Photometer (SP2) Schematic Single Particle Soot Photometer (SP2) Principle of the SP2 Optical Head IR Laser Now I’ll show you how this works on a sample particle detection Provides single particle: BC mass: 0.15 – 0.6 µm. Sampling at ¼ lpm.  Sufficient sensitivity to quantify BC MMR throughout vertical profiles

Schematic SP2 Status Principle of the SP2 Optical Head Humidified-Dual SP2 proposed for KORUS-AQ, just before ATom. This configuration includes two SP2s, one that can be humidified. For Atom we would fly one SP2 cold as a spare. The HD-SP2 has flown on the DC8 previously. For ATom-1; Joseph Katich will fly CA - > NZ, Joshua Schwarz will fly NZ -> CA Quicklook programs already set up from HIPPO. RTTM/REVEAL communications needs attention to ensure full functionality. This can be done, in part, during the KORUS integration and deployment.