Forma&on and contribu&on of highly oxygenated organic molecules (HOM) to the growth of new par&cles over the boreal forest

Transcription

1 Forma&on and contribu&on of highly oxygenated organic molecules (HOM) to the growth of new par&cles over the boreal forest Pontus Roldin Nuclear Physics Lund University, Lund Sweden

2 Model & measurement framework ADCHEM Field measurements (Hyytiälä, Pallas) ADCHAM Chamber exp. (JPAC) ADCHEM; Roldin et al., Atmos. Chem. Phys., 11, , 2011 ADCHAM; Roldin et al., Atmos. Chem. Phys., 14, 14, , 2014

3 Model & measurement framework ADCHEM Field measurements (Hyytiälä, Pallas) Part 1 ADCHAM Chamber exp. (JPAC) ADCHEM; Roldin et al., Atmos. Chem. Phys., 11, , 2011 ADCHAM; Roldin et al., Atmos. Chem. Phys., 14, 14, , 2014

4 Model & measurement framework Part 2 ADCHEM Field measurements (Hyytiälä, Pallas) Part 1 ADCHAM Chamber exp. (JPAC) ADCHEM; Roldin et al., Atmos. Chem. Phys., 11, , 2011 ADCHAM; Roldin et al., Atmos. Chem. Phys., 14, 14, , 2014

5 Formation of Highly Oxygenated Molecules (HOM; O:C 0.7) by autoxidation of monoterpenes (MT) MT C10 H16 + O3!C10 H15 O2 -OO C10 H15 O2 -OO C10 H15 O4 -OO C10 H15 O6 -OO C10 H15 O8 -OO H-shift+O2 H-shift+O2 H-shift+O2 H-shift+O2 (! = 9 % for α-pinene) st C10 H15 O4 -OO (1 H-shift + O2) C10 H15 O6 -OO (2 H-shift + O2) C10 H15 O8 -OO (3 H-shift + O2) C10 H15 O10 -OO (4 H-shift + O2) nd rd th Reactions terminating the autoxidation, leading to formation of stable HOMs: C10 H15 Ox -OO + HO2 C10 H15 Ox -OH C10 H15 Ox -OO +RO2 α C10 H15 Ox -OH + β C10 H14 Ox =O + γ C10 H15 Ox -O + (1-α-β-γ) C20 H30 Ox+4 C10 H15 Ox -OO + NO α C10 H15 Ox -ONO2 + β C10 H14 Ox =O + γ C10 H15 Ox O + (1-α) NO2 + fragmentation prod. C10 H15 Ox OO C10 H15 Ox OH The HOM mechanism comprise 822 reactions and 80 compounds. It keeps the carbon number and mass balance The mechanism is fully coupled to the Master Chemical Mechanism v 3.3.1

6 Highly Oxygenated Molecules contribu6on to SOA forma6on Are HOM Extremely low-vola&lity organic compounds (ELVOC)? Results from Kurtén et al., (J. Phys. Chem A 2016)

7 Highly Oxygenated Molecules contribu6on to SOA forma6on Are HOM Extremely low-vola&lity organic compounds (ELVOC)? ELVOC: p sat <10-9 Pa Results from Kurtén et al., (J. Phys. Chem A 2016)

8 10-50 km Part 2: Implemen&ng the knowledge from the smog chamber experiments into the process-based atmospheric chemistry transport model ADCHEM 2-3 km Wind direction 10 s ADCHEM; Roldin et al., Atmos. Chem. Phys., 11, , 2011

9 10-50 km Part 2: Implemen&ng the knowledge from the smog chamber experiments into the process-based atmospheric chemistry transport model ADCHEM Typically 40 ver&cal layers of which 4 are inside the forest canopy. BVOC emissions from MEGAN or LPJ- Guess. 2-3 km Wind direction 10 s ADCHEM; Roldin et al., Atmos. Chem. Phys., 11, , 2011

10 10-50 km Part 2: Implemen&ng the knowledge from the smog chamber experiments into the process-based atmospheric chemistry transport model ADCHEM Typically 40 ver&cal layers of which 4 are inside the forest canopy. BVOC emissions from MEGAN or LPJ- Guess. 2-3 km The Atmospheric Cluster Dynamics Code (ACDC) is explicitly simula&ng the growth and losses of molecule clusters which lead to new par&cles in the atmosphere. Currently we only consider clusters consis&ng of ammonium and sulfuric acid. Wind direction 10 s ADCHEM; Roldin et al., Atmos. Chem. Phys., 11, , 2011

11 Contribution of HOMs to new particle activation and growth in the atmosphere (Pallas NPF events ) Öström et al., ACP 2017

12 Contribution of HOMs to new particle activation and growth in the atmosphere (Pallas NPF events ): Öström et al., ACP 2017

13 Contribution of HOMs to new particle activation and growth in the atmosphere (Pallas NPF events ): Median particle number size distributions from 10 NPF events at Pallas in northern Finland Öström et al. ACP 2017

14 ADCHEM model simula6ons of NPF and growth at Pallas: Median PN(D p > 50 nm) from 10 NPF events at Pallas in northern Finland Öström et al. ACP 2017

15 Summary and conclusions We have developed a unique HOM gas-phase mechanism and coupled it to Master Chemical Mechanism v3.3.1 The HOM mechanism has been implemented into the process-based chemistry transport model ADCHEM. According to our model simula&ons HOM are crucial for the growth of new par&cles into the cloud condensa&on nuclei (CCN) size range over the sub-arc&c forest region. Over the Boreal forest in Southern Finland the contribu&on of HOM to the number of CCN during a new par&cle forma&on intensive period in Spring 2014 was approximately 15 %.