Difference between revisions of "Minutes of the aerosol working group meeting 12/12/2013"

Revision as of 14:28, 13 December 2013

Next UKCA aerosol teleconference to be held Thursday 22nd November between Leeds & MO

Present: to appear.

Relevant Files for Discussion

Latest GA4 sensitivity results:

Scavenging coefficient sensitivity. The scavenging coefficients for accumulation and coarse modes in convective regimes was reduced from 1.0 --> 0.5

 *   Impact on AOD 
 *   Impact on Burdens 
 *   Budgets Expt   *   Budgets Control

GA6 Performance:

Latest GA6 AODs Earlier GA6 AODs with GA4 for comparison

Doubling BB emissions
In this experiment BB emissions and SOA yield from monoterpene were both doubled, as an attempt to increase AOD in the tropics.

Mass loading of BC and OC has increased by almost a factor of 2.
The aitken insoluble mass pretty much doubles
The accumulation soluble mode is pumped up a little, particularly over tropical continents.
AOD has moved in the right direction -now ~ 0.05 higher over tropical continents. I think we still need a further 0.05 - 0.1 increase to match observations.
The AOD also increases by a similar amount (~0.05) in some N. hemisphere mid-latitude regions where there are monoterpene and BB emissions.
This is a little suprising as the emissions of BB and monoterpene are much smaller in these mid-latitude regions
AOD increase in the tropics is quite limited to the continental source regions - indicating that the lifetime of the aerosol in the tropics is still quite low.

burden_ajkzi_anmad.pdf aod_maps_ajkzi_anmad.pdf

Decreasing ageing rates
Attached are the annual-mean results from the test to decrease the ageing rate of carbonaceous aerosols. The Control is amtj-u, the Experiment is amtj-w.

Bottom line: carbonaceous burdens are

decreased slightly in the nucleation mode (OC -11%)
increased in both Aitken modes (BC[sol] +28%; OC[sol] +23%; BC[ins] & OC[ins] both more than +200%)
increased in the coarse mode (BC +60%; OC +18%)

....but sadly, the accumulation mode burdens for both BC and OC are decreased (both c. -4%), so there's little impact on AOD, and such changes as there are could easily be due to interannual variability. AODs_amtjw_cf_amtju.pdf burdens_etc_amtjw_cf_amtju.pdf

Summary of discussion:

Things will be discussed.

@@ Line 3: / Line 3: @@
 Present: to appear.
-Relevant Files for Discussion:
+===Relevant Files for Discussion===
-Latest GA4 sensitivity results:
+'''Latest GA4 sensitivity results:'''
 * Scavenging coefficient sensitivity. The scavenging coefficients for accumulation and coarse modes in convective regimes was reduced from 1.0 --> 0.5
   * {{pdf|Acc_cor_scavC_aods.pdf | Impact on AOD}}
@@ Line 11: / Line 11: @@
   * {{pdf|Budgets_annvl.pdf | Budgets Expt}}  * {{pdf|Budgets_annvi.pdf | Budgets Control}}
-GA6 Performance:
+'''GA6 Performance:'''
 {{pdf|GA6_AOD_evaluation_ansff.pdf | Latest GA6 AODs}}
 {{pdf|AOD_GA4_GA6_eval.pdf | Earlier GA6 AODs with GA4 for comparison}}
+<br>
+'''Doubling BB emissions'''<br>
+In this experiment BB emissions and SOA yield from monoterpene were both doubled, as an attempt to increase AOD in the tropics.
+* Mass loading of BC and OC has increased by almost a factor of 2.
+* The aitken insoluble mass pretty much doubles
+* The accumulation soluble mode is pumped up a little, particularly over tropical continents.
+* AOD has moved in the right direction -now ~ 0.05 higher over tropical continents. I think we still need a further 0.05 - 0.1 increase to match observations.
+* The AOD also increases by a similar amount (~0.05) in some N. hemisphere mid-latitude regions where there are monoterpene and BB emissions.
+* This is a little suprising as the emissions of BB and monoterpene are much smaller in these mid-latitude regions
+* AOD increase in the tropics is quite limited to the continental source regions - indicating that the lifetime of the aerosol in the tropics is still quite low.
+{{pdf|burden_ajkzi_anmad.pdf |burden_ajkzi_anmad.pdf}} {{pdf|aod_maps_ajkzi_anmad.pdf |aod_maps_ajkzi_anmad.pdf}}
+'''Decreasing ageing rates'''<br>
+Attached are the annual-mean results from the test to decrease the ageing rate of carbonaceous aerosols. The Control is ''amtj-u'', the Experiment is ''amtj-w''.
+Bottom line: carbonaceous burdens are
+* decreased slightly in the nucleation mode (OC -11%)
+* increased in both Aitken modes (BC[sol] +28%; OC[sol] +23%; BC[ins] & OC[ins] both more than +200%)
+* increased in the coarse mode (BC +60%; OC +18%)
+....but sadly, the accumulation mode burdens for both BC and OC are decreased (both c. -4%), so there's little impact on AOD, and such changes as there are could easily be due to interannual variability.
+{{pdf|AODs_amtjw_cf_amtju.pdf |AODs_amtjw_cf_amtju.pdf}} {{pdf|burdens_etc_amtjw_cf_amtju.pdf |burdens_etc_amtjw_cf_amtju.pdf}}