Difference between revisions of "Scale factors for anthropogenic emissions"

Revision as of 15:33, 23 February 2010

This page describes the methodology of the interannual scaling factors used for anthropogenic emissions in GEOS-Chem. In general, the various emissions inventories are for a particular year (or in some cases, for multi-years). A set of scale factors is required to adjust the emissions totals to what the

Overview

From van Donkelaar et al., [2008]:

We scale all regional and global inventories from their respective base year to 2003, the last year of available statistics, unless its base year is after 2003. Our approach follows Bey et al. (2001) and Park et al. (2004). Emissions are scaled according to estimates provided by individual countries, where available. These countries/regions include the United States, Canada, Japan and Europe. NOx emissions of remaining countries are scaled proportional to changes in total CO2 emissions. SOx emissions are similarly scaled to solid fuel CO2 emissions and CO emissions to liquid fuel CO2 emissions. CO2 emission data are obtained from the Carbon Dioxide Information Analysis Center (CDIAC).

Philippe Le Sager wrote:

Note that the scale factor have been updated since van Donkelaar et al [2008] to go up to 2005, and are based on REAS data now for South East Asia: Relative changes in the REAS inventory (Ohara et al., ACP, [2007]) over East Asia have been used.

This should be a good improvement as REAS emissions are gridded, rather than national scale emissions, giving us much better spatial detail. Also, these scalars are now based on actual NOx, SOx and CO emission estimates, not strictly an assumed proportionality between total, solid and liquid CO2 emissions.

Validation

See van Donkelaar et al., [2008].

References

1. Anthropogenic emissions inventories in GEOS-Chem v8-02-03 (and higher versions)
2. Anthropogenic emissions inventories used in GEOS-Chem v8-01-04 thru v8-02-02
3. Anthropogenic emissions inventories prior to GEOS-Chem v8-01-01
4. Ohara, T., H. Akimoto, J. Kurokawa, N. Horii, K. Yamaji, X. Yan, and T. Hayasaka, An Asian emission inventory of anthropogenic emission sources for the period 1980–2020, Atmos. Chem. Phys.,, 7, 4419-4444, 2007. ACP site
5. van Donkelaar, A., R. V. Martin, W. R. Leaitch, A.M. Macdonald, T. W. Walker, D. G. Streets, Q. Zhang, E. J. Dunlea, J. L. Jimenez, J. E. Dibb, L. G. Huey, R. Weber, and M. O. Andreae, Analysis of Aircraft and Satellite Measurements from the Intercontinental Chemical Transport Experiment (INTEX-B) to Quantify Long-Range Transport of East Asian Sulfur to Canada, Atmos. Chem. Phys., 8, 2999-3014, 2008. PDF

--Bob Y. 09:41, 23 February 2010 (EST)

Known issues

Large jump in emissions in Asia from 2005 to 2006

Jennifer Logan wrote:

I've inadvertently discovered what seems to be a problem with the time dependent emissions, that likely relates to when it switches from one base inventory to another. For CO, there is a huge difference between emissions in Asia for 2005 and 2006 - see Junhua's plots below:

1. 2005 vs 2006 emissions: SE Asia only
2. 2005 vs 2006 emissions: Larger region

I am guessing that this is because 2005 is scaled forward from the Streets inventory for 2000 (his latest for China I hope, not the original TRACE-P one), while 2006 is taken from the new Streets inventory for INTEX-B.

Jennifer Logan wrote:

You are right for Streets. There is no backward scaling. So for 2006 and after, we use Streets 2006 and for 2005 and before we use Streets 2000.

I guess you would prefer to take the data from the closest inventory instead. This looks like relatively easy to implement in the code but there is still the question of the scaling factors.

Aaron van Donkelaar wrote:

Lok Lamsal (cc'd) also found a jump with the NOx emissions. We indeed traced to back to the REAS inventory, which is based upon projections past 2003 that significantly underestimates regional growth.

I have already provided updated code to Bob (amongst the modifications for the nested NA and nested EU simulations that will go into GEOS-Chem v8-02-05) which include 2006 scalars and backscale from the 2006 Streets inventory. This, of course, really only addresses the problem for simulations of recent time periods, as there will now be a jump at 2000, but is probably sufficient for most users. Lok has written to the Streets group requesting their estimates of annual changes, but I don't know if he has heard anything back.

Jennifer Logan wrote:

One more thing. I looked at the Zhang et al. (2009) paper on the INTEX-B inventory. They have also redone their 2001 inventory using the improved methodology of the INTEX work, so we shouldn't even be using the old TRACE-P inventory for 2000, but their revised inventory for 2001. They are different by 27% for NOx according to Table 5 in Zhang et al., 2009.

How do you backscale from 2006? Which scaling factors do you use? If the REAS ones are not good going forward, they will be no good going backwards.

Also, we should definitely backscale from 2006 for Asian VOC emissions.

For pre-2000, it might be best to backscale from the improved 2001 Streets inventory, as least for Asia in the 1990s.

Aaron van Donkelaar wrote:

I think Yuxuan Wang implemented the Streets inventory, so she may know differently, but I don't think the Streets inventory has been updated to the INTEX-B methodology from the 2009 paper. CO emissions, however, were updated at some point to 2001 to include improved estimates.

The scalars are the same as before, just extended by a year....The scalars are generally in the right direction, just underestimated, so they should be more accurate than using the original inventory if we are relatively near the base inventory year.

There are no scalars for VOC emissions...

If the Street inventory is active, emissions over Asia are presently backscaled from the 2000/2001 emissions for pre-2000.

Lok Lamsal wrote:

My concern was that emissions trend (for NOx) in Asia is very small (~5% from 2003 to 2006 in China) mainly because of the use of REAS projections. Recently I have obtained the emissions for 2005 from Ohara which indicates a trend of about 9%/year. This suggests that we need to update our implementation in GEOS-Chem. I am going to obtain Streets inventory for 2003 (that uses the INTEX-B methodology) from Qiang Zhang in early March. These are the data we will have to implement in GEOS-Chem.

--Bob Y. 10:17, 23 February 2010 (EST)