Data used in the assimilation

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Cristina Russo

Jul 14, 2021, 9:56:12 AM7/14/21
Good morning,

My name is Cristina Russo and I work for the South African Environmental Observation Network (SAEON). We are currently performing a model evaluation on the three mainly used global models (GLORYS, BRAN and HYCOM) in and around South Africa's oceans. 

As part of this investigation we are looking to detail the data assimilated in each product, e.g. GLORYS assimilates the CORA 5.2 dataset. So I was wondering if you would be able to provide me with a list of the assimilated datasets. This would be really helpful towards executing a comprehensive evaluation of these models. 

Thank you in advance.

Kind regards,
Cristina Russo

Alan Wallcraft

Jul 14, 2021, 11:19:26 AM7/14/21
to Forum, Cristina Russo
The general description is:

The system uses the Navy Coupled Ocean Data Assimilation (NCODA) system (Cummings, 2005; Cummings and Smedstad, 2013) for data assimilation. NCODA uses the 24-hour model forecast as a first guess in a 3D variational scheme and assimilates available satellite altimeter observations, satellite, and in-situ sea surface temperature as well as in-situ vertical temperature and salinity profiles from XBTs, Argo floats and moored buoys. Surface information is projected downward into the water column using Improved Synthetic Ocean Profiles (Helber et al., 2013).

E.J. Metzger, R.W. Helber, P.J. Hogan, P.G.Posey, P.G. Thoppil, T.L. Townsend, A.J. Wallcraft, O.M. Smedstad, and D.S. Franklin, 2017:
Global Ocean Forecast System 3.1 Validation Testing
NRL Report NRL/MR/7320--17-9722

J. A. Cummings and O. M. Smedstad, 2014:
Ocean Data Impacts in Global HYCOM
Journal of Atmospheric and Oceanic Technology vol 31 doi:10.1175/JTECH-D-14-00011.1

J. A. Cummings and O. M. Smedstad, 2013:
Variational Data Assimilation for the Global Ocean
Data Assimiltion for Atmospheric, Oceanic and Hydrologic Applications vol II, chapter 13

T.L. Townsend, C.N. Barron and R.W. Helber, 2015:
Ocean Prediction with Improved Synthetic Ocean Profiles (ISOP)
NRL Review 105-112

There are tables of observation sources in the Cummings papers, and the same kinds of observations are assimilated now but the details depends on what is available in near real time and may change over time.


Alma Carolina Castillo Trujillo

May 10, 2022, 1:30:13 PM5/10/22
to Alan Wallcraft, Forum
Hi HYCOM forum,

I am following up on an old email regarding the sources of data assimilated by HYCOM.
The tables of observation sources from the Cunnings papers clearly show that T/S profiles are obtained from XBTs, CTDs, buoys and other instruments. But, I can not find where, specifically, they get the T/S datasets from. It is a specific dataset such as WOD, WOA or CORA?

Thank you very much. We are trying to compare several reanalyses with observations and it is important that we know if our XBTs and buoys are assimilated by HYCOM.


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Alma Carolina Castillo-Trujillo, PhD
Postdoctoral Researcher
Scripps Institution of Oceanography, UCSD
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