Earthdata Webinar: A Clearer View of the Haze–Using NASA GES DISC Data Tools to Examine the June 2020 Sahara Dust Event

[GES DISC - jimacker]

Webinar announcement:

A Clearer View of the Haze – Using NASA GES DISC Data Tools to Examine the June 2020 Sahara Dust Event


Join us as we explore how GES DISC tools and data products can augment ongoing vital research on the dynamics of dust transport in Earth’s atmosphere. We will investigate the June 2020 Sahara Dust Event over Barbados as our use case.

Register at the link above!

Presenter: Dr. James Acker, NASA GES DISC
Event Date(s) and Time(s):
Sep 23, 2020 at 2:00 PM EDT - Sep 23, 2020 at 3:00 PM EDT
Location: Online
Hosted by: NASA EOSDIS
Organized by: NASA EOSDIS Communications Team

[GES DISC - jimacker]

On Friday, October 2, this Earthdata Forum thread will be hosting a Forum Active Discussion (FAD) about the Webinar which was presented last week. The Webinar can be viewed on YouTube at this link:

https://www.youtube.com/watch?v=CwMOF4FzULE

If you have questions about the tools described, or about Saharan dust outbreaks, or about remote sensing of dust in the atmosphere, just "Reply" in this thread with your question, and on Friday we'll be looking for these questions so we can reply rapidly. Even if you can't participate on Friday, questions on these topics can still be asked here.

[leonsimons]

Thank you for the clear Earthdata Webinar,

I am interested in past, present and future NASA GES DISC data and data from Barbados on sulfates over and from the Atlantic attributed to emissions from shipping.
New regulation from the International Maritime Organisation (IMO 2020) which came into effect on Januari 1st 2020, is expected to reduce SOx emissions from shipping by 77% (8.5 million metric Tons annually. Extensive research on the regional and global effects (aerosol and cloud formation, the energy balance, ocean stratification etc.) are needed. Early research showed that the aerosol forcing from shipping could be as high as -0.6W/m², which could be greatly reduced because of this new regulation and thus lead to rapid warming.

Do you have ongoing research on this matter and or available data that can help in the assessment of the impact of reduced SOx emissions from global shipping (notably in the Atlantic region)?

[GES DISC - jimacker]

Leon,

Thanks for asking. The GES DISC has a couple of SO2 data products that might be examined. For today we did not have our SMEs for these data on alert, but they could be contacted.

The OMI SO2 data product is more suited for large SO2 emissions, such as from volcanoes, but could be examined. TROPOMI also has SO2. This search link will provide access to both:

https://disc.gsfc.nasa.gov/datasets?key ... SO2&page=1

The MERRA-2 reanalysis data set also has SO2. We wrote about that data here:
https://disc.gsfc.nasa.gov/information/ ... ng%20Lanes

Our Level 3/4 Data Subsetter can assist with the use of these data in the MERRA-2 data files; use "Subset / Get Data" for variable and spatial subsetting:
https://disc.gsfc.nasa.gov/datasets?key ... A-2&page=1

[leonsimons]

Thank you for your detailed answer Jim,

The 'SO2 surface mass concentration 2010 average' is interesting, as it clearly shows the elevated concentration of SO2 across the shipping routes.

What will be the most user friendly software to make similar comparisons analyses for comparing periods (for example SO2 surface mass concentration average over the first quarter of the year, each year since the year 2000)? Would that be through GIOVANNI or do you advise downloading the data and then using NASA Panoply to plot the data?  
I started making a monthly comparison with NASA Worldview of 'MERRA2_SO2_Column_Mass_Density_Monthly' (see link below), but the resolution here is lower and values below 1.5-e6 kg/m² (which covers most of the area over the oceans) are not clearly distinguished, unlike in the example you shared.  

https://worldview.earthdata.nasa.gov/?v ... true&cv=31

[leonsimons]

I managed with Panoply to compare the SO2 Surface Mass Concentration ENSEMBLE data of 2010-08 with 2020-08, both Log10 and Scalar, see attached. These look almost identical, while SO2 emissions from shipping (should) have been reduced with 77%. What could cause this similar image?

[GES DISC - jimacker]

These are interesting images. Is the source of the 77% number a citation of a reduction in shipping traffic?

Note that MERRA-2 is a model, not actual observational data. Determining how the algorithm generates the values of the MERRA-2 variable would require more effort. I can ask our MERRA-2 experts for their insight.

Also, it would be interesting to create a difference map of the 2010 vs 2020 data. Here is the link to our How-To document demonstrating how to do this. https://disc.gsfc.nasa.gov/information/ ... nd%20Excel

Finally, just a thought -- even if shipping traffic is reduced, as long as there is still commercial shipping, most ships will still follow the same shipping routes. So even with a reduction in traffic, if there is a consistent supply of SO2 from the ships in the same region, the changes may be difficult to detect, which is why a difference map may be more effective.

[leonsimons]

Thank you.

The 77% reduction is cited from the International Maritime Organisation. See this link and attached highlights. All ships need to use low sulfur fuel (max 0.5% in stead of 3.5% sulfur fuel content) or scrubbers starting January 1st 2020.
The 77% reduction translates to approximately 8.5 million metric tons (=Tg) of anthropogenic SOx, which is about 10% of the global SOx emissions. At this scale the impact should be visible. I would be interesting to hear the insight of MERRA-2 experts on the generated values.

Another location where a reduction of SOx emissions should be visible is over China, which reduced emissions by 75%, while India should see an increase, because emissions rose by 50% in the same period according to satellite based research: https://www.nature.com/articles/s41598-017-14639-8
The global warming effect of the reduction in SOx emissions is estimated to be considerable: https://iopscience.iop.org/article/10.1 ... ab9e21/pdf

I will have a look and try to create a difference map of the 2010 vs 2020 data.

[leonsimons]

Find attached the comparison of 2019 and 2020 for the months of both March and August. It's difficult to determine the relevance, especially without more insight in the MERRA-2 model and its underlying data and assumptions.

Comparing the average of for example the first half year of each year would likely be more interesting, given other variables at play. How can I obtain this half year average for SO2 Surface mass effectively? I did't manage with Giovanni myself.

[GES DISC - jimacker]

Thank you. I will inquire to the MERRA-2 group to see if they can assist.

Using Giovanni, you can make a six-month average simply by making the Begin Date January and the End Date June, when using monthly data. This will average the data over the entire period.

Please do me a favor. Send your attachments to our Help Desk so I can see them full-scale. Our Help Desk email address is gsfc-help-disc@lists.nasa.gov We can continue to discuss here, but I can't view them at full resolution here.