Details:

Journal Title:
Geoscientific Model Development
Personal Author:
Chai, Tianfeng ; Stein, Ariel ; Ngan, Fong
Chai, Tianfeng ; Stein, Ariel ; Ngan, Fong Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; ARL (Air Resources Laboratory) ; NESDIS (National Environmental Satellite, Data, and Information Service) ; CICS (Cooperative Institute for Climate and Satellites)
OAR (Oceanic and Atmospheric Research) ; ARL (Air Resources Laboratory) ; NESDIS (National Environmental Satellite, Data, and Information Service) ; CICS (Cooperative Institute for Climate and Satellites) Less -
Description:
A Hybrid Single-Particle Lagrangian Integrated Trajectory version 4 (HYSPLIT-4) inverse system that is based on variational data assimilation and a Lagrangian dispersion transfer coefficient matrix (TCM) is evaluated using the Cross-Appalachian Tracer Experiment (CAPTEX) data collected from six controlled releases. For simplicity, the initial tests are applied to release 2, for which the HYS-PLIT has the best performance. Before introducing model uncertainty terms that will change with source estimates, the tests using concentration differences in the cost function result in severe underestimation, while those using logarithm concentration differences result in overestimation of the release rate. Adding model uncertainty terms improves results for both choices of the metric variables in the cost function. A cost function normalization scheme is later introduced to avoid spurious minimal source term solutions when using logarithm concentration differences. The scheme is effective in eliminating the spurious solutions and it also helps to improve the release estimates for both choices of the metric variables. The tests also show that calculating logarithm concentration differences generally yields better results than calculating concentration differences, and the estimates are more robust for a reasonable range of model uncertainty parameters. This is further confirmed with nine ensemble HYS-PLIT runs in which meteorological fields were generated with varying planetary boundary layer (PBL) schemes. In addition, it is found that the emission estimate using a combined TCM by taking the average or median values of the nine TCMs is similar to the median of the nine estimates using each of the TCMs individually. The inverse system is then applied to the other CAPTEX releases with a fixed set of observational and model uncertainty parameters, and the largest relative error among the six releases is 53.3 %. At last, the system is tested for its capability to find a single source location as well as its source strength. In these tests, the location and strength that yield the best match between the predicted and the observed concentrations are considered as the inverse modeling results. The estimated release rates are mostly not as good as the cases in which the exact release locations are assumed known, but they are all within a factor of 3 for all six releases. However, the estimated location may have large errors.
Source:
Geoscientific Model Development, 11(12), 5135-5148.
DOI:
https://doi.org/10.5194/gmd-11-5135-2018
Document Type:
Journal Article
Funding:
Grant no. NA09nes4400006
Rights Information:
CC BY
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:5bbe03718eefb169b5e77cb7173aa24f779bbfff1cccc5a42817c4eb7b636e5f
Download URL:
https://repository.library.noaa.gov/view/noaa/20934/noaa_20934_DS1.pdf
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