4th General Assembly, University of Bern, 12-13 December 2017

The 4th and last General Assembly of the ERA-CLIM2 project (GA4), held at the University of Bern on 12-13 December 2017, was attended by about 30 people. GA4 followed GA1 held in November 2014 at ECMWF, GA2 held in December 2015 at EUMETSAT and GA3 held in January 2017 at the University of Vienna. During the meeting, the project's work was revised, and key results were discussed.

ERA-CLIM2 started in January 2014 with the aim to improve capacity for producing state-of-the-art climate reanalyses that extend back to the early 20th century. In particular, it aimed to provide a substantial contribution to rescue and prepare the observations and to advance the data-assimilation systems required to generate operational reanalysis, such as the ones planned by the Copernicus Climate Change Service (C3S).

The ERA-CLIM2 activities have been grouped into four main themes:
- Observation data rescue and post-processing (mainly WP3)
- Data assimilation methods (mainly WP2)
- Reanalysis production (mainly WP1 and WP5)
- Evaluation and uncertainty estimation (mainly WP4)

At GA4, all aspects of the project were reviewed (the GA4 presentations can be accessed following the links below).

The last 12 months of the project have seen the production of CERA-SAT, which covers 9 years of the satellite era (2008-2016), and the completion of the land and carbon climate reanalyses, CERA-20C/Land and CERA-20C/Carbon. These reanalyses were driven by the coupled ocean, sea-ice, land and atmosphere climate reanalysis of the 20th century, CERA-20C. Furthermore, more data have being rescued and post-processed, and have been delivered and copied to relevant data bases so that they can be used in future reanalysis (e.g. in the C3S ERA5 reanalysis under production, and in the future C3S ERA6 reanalysis). Advances in the assimilation methods developed within the project have also been integrated in the software depositories, and are ready to be tested in future reanalyses' productions. All the project's deliverables are expected to be completed on-time and with the required high-level quality by the end of the project.


Welcome and Introduction
R Buizza


Overview WP1/WP5
P Laloyaux

Biogeochemical reanalysis
C Perruche

D Schepers

Land Carbon analysis
P Peylin/N Vuichard

CERA-SAT ocean component and further developments
E de Boisseson

Tropical cyclone representation
Y Kosaka

Improving the use of historical surface and upper-air observations
P Dahlgren

Overview of WP2
M Martin

SST assimilation developments
D Lea and J While

Sea-ice assimilation developments
C-E Testut

Ensemble B in NEMOVAR
A Weaver

Ensemble covariances in coupled DA
A Storto

Impact of 4DVar and research into fully coupled
A  Vidard

Land carbon optimisations
P Peylin

Strengths/weaknesses in existing coupled DA, coupled error covariances and model drift/bias correction
K Haines/X Feng

Variational bias correction of sea surface temperature observations
J While/M Martin

WP3 Overview and accomplishments
S Brönnimann

RIHMI Input for WP3 within ERA CLIM2 Project
A Sterin

Data Rescue, QC and a metadatabase: FCiências.ID's contribution to WP3
M A Valente

Upper air data rescue Météo-France's contribution to WP3
S Jourdain

Snow in situ and satellite data
J Pulliainen

Satellite data records for reanalysis
J Schulz

Met Office contribution to WP3 in 2017
N Rayner

Overview of WP4
L Haimberger

Uncertainties and bias corrections for radiosonde temperatures
L Haimberger

Bias corrections for radiosonde humidity
M Blaschek

Quality control for observations
M A Valente

ERA20C and Cera-20C precipitation in comparison to GPCC daily and monthly analyses
M Ziese

Uncertainties associated to the land carbon balance; comparison between ORCHIDEE and CTESSEL
P Peylin

Comparison with other reanalyses, Trends and low frequency variability
L Haimberger

Comparisons of ERA reanalyses with the station Upper Air data
A Sterin

Uncertainties in energy budgets
L Haimberger & M Mayer