SLP drops in 20CR not present in ERA-interim reanalysis

Submitted by alba.cid on Wed, 05/06/2015 - 02:48


I detected strong drops in the SLP from 20CRv2 not present in the SLP from ERA-interim reanalysis. This happens at some areas, mainly tropical but not exclusively; an example can be seen below for

lon = 134ºW and lat = 14ºN (lower panel is just a zoom of the upper panel).  As you can see, differences between both databases can reach 20 mb.

I am using 6-hourly values from both datasets. ERA-interim was downloaded from

and 20CRv2 was downloaded from…


Does anybody know if there is a phisical explanation for those drops or if they are outliers?.





Alba Cid (not verified)

Mon, 05/11/2015 - 06:38

We didn't check the tropical cyclones because we assumed that non of the global reanalysis was good at gathering information of TC... But you are right and those drops agree with known TC. Does this mean that despite the coarser resolution of 20CR, it is better than ERA-interim in reproducing TC? What is the reason for this? Thank you very much for your answer

Dear Dr. Cid, As noted in the paper Compo et al. (2011, , 20CR version 2 assimilates pressure reports from the International Best Track Archive for Climate Stewardship (IBTrACS, versions denoted in paper). Whether 20CR is "better" is a scientific question that would need further research for you to draw your own conclusions. Please let me know if I can be of more help. best wishes, gil compo