On "Observation Minus Reanalysis" Method: A View from Multidecadal Variability

TitleOn "Observation Minus Reanalysis" Method: A View from Multidecadal Variability
Publication TypeJournal Article
Year of Publication2013
JournalJournal of Geophysical Research - Atmospheres
Number14
Pages7450–7458
Date Published07/2013
Abstract / Summary

The observation minus reanalysis (OMR) method is widely used to investigate the impact of urbanization and land use change on climate. Here we present the OMR trends for the periods of 1979–1998 and 1989–2008 in eastern China, which appear inconsistent for the regions experiencing rapid urbanization during recent decades. Using Ensemble Empirical Mode Decomposition, we extract the secular trend and multidecadal variability (MDV) from the temperature observations at stations and the corresponding reanalysis data for the last century and find that, in general, MDV in the reanalysis data is weaker than that in the station observations. This systematic difference considerably modulates the magnitude of the OMR trends during different periods, leading to inconsistent estimates of the impact of urbanization. After MDV adjustment, the OMR trends for Beijing and Shanghai are consistent for the different periods, about 0.04°C–0.1°C/decade, much smaller than some previous estimates. We caution those using OMR methods to estimate the effect of urbanization and also for those using reanalysis data for a limited period in studies of this kind.

DOI10.1002/jgrd.50574
Journal: Journal of Geophysical Research - Atmospheres
Year of Publication: 2013
Number: 14
Pages: 7450–7458
Date Published: 07/2013

The observation minus reanalysis (OMR) method is widely used to investigate the impact of urbanization and land use change on climate. Here we present the OMR trends for the periods of 1979–1998 and 1989–2008 in eastern China, which appear inconsistent for the regions experiencing rapid urbanization during recent decades. Using Ensemble Empirical Mode Decomposition, we extract the secular trend and multidecadal variability (MDV) from the temperature observations at stations and the corresponding reanalysis data for the last century and find that, in general, MDV in the reanalysis data is weaker than that in the station observations. This systematic difference considerably modulates the magnitude of the OMR trends during different periods, leading to inconsistent estimates of the impact of urbanization. After MDV adjustment, the OMR trends for Beijing and Shanghai are consistent for the different periods, about 0.04°C–0.1°C/decade, much smaller than some previous estimates. We caution those using OMR methods to estimate the effect of urbanization and also for those using reanalysis data for a limited period in studies of this kind.

DOI: 10.1002/jgrd.50574
Citation:
Wang, J, Z Yan, PD Jones, and J Xia.  2013.  "On "Observation Minus Reanalysis" Method: A View from Multidecadal Variability."  Journal of Geophysical Research - Atmospheres 7450–7458.  https://doi.org/10.1002/jgrd.50574.