6B: Manage a postdoctoral program to coordinate and develop data-assimilation infrastructure that is common across applications

The NCAR data assimilation (DA) initiative, with ACOM representation, sponsored a postdoctoral program. The overall goals were to:

  • Bring promising young scientists to NCAR to augment expertise and accelerate progress in specific, priority areas of the NCAR DA Program
  • Train the next generation of DA researchers and foster later links with academic and operational communities
  • Encourage adoption of common tools and infrastructure throughout NCAR by allowing externally funded or laboratory-specific projects to leverage resources from the DA Program
  • Encourage development of tools and infrastructure within the DA Program that are flexible and effective across a variety of projects through early exposure of those tools to diverse applications.


At ACOM we provided co-sponsorship (from NASA funding) to hire Dr. Zhe Jiang, who is now an assistant professor at the Univ. of Science and Technology, China (USTC) in Hefei, China.

A primary focus of the postdoctoral work was a study that showed a slowdown in reductions in US pollution emissions in recent years, in contrast to what is expected from EPA emission inventories. These results were published in Jiang et al., PNAS, 2018 and are significant for understanding the effects of regulations on ozone-precursor emissions. The study used NOx emissions derived from assimilating O3, CO, and NO2 measured by NASA Aura satellite instruments (OMI, TES, and MLS) and CO emissions derived from assimilating MOPITT observations from the NASA Terra satellite to show emission reductions of up to 20% in urban regions between 2005-2009 but much smaller reductions in emissions and ozone after 2009, in contrast to expectations from bottom-up EPA inventories. A fuel based analysis of bottom-up inventories suggests that these NOx emissions trends are due to the increasing relative importance of emissions from off-road vehicles, industrial and residential sources factories and a lower than expected decline in diesel truck emissions. This paper received substantial press attention and has already been cited 5 times since the April 2018 publication date.

Change in anthropogenic NO2 emissions.
Figure 1. Change in anthropogenic NO2 emissions. Click for larger image.


Jiang, Z.,  B. C. McDonald, H. Worden, J. R. Worden, K. Miyazaki, Z. Qu, D. K. Henze, D. B. A. Jones, A. F. Arellano, E. V. Fischer, L. Zhu, K. F. Boersma, Unexpected slowdown of US pollutant emission reduction in the past decade, Proc. Nat. Acad. Sci., 2018 DOI: 10.1073/pnas.1801191115