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ReanalysisCoupled Data Assimilation at NCEP

Presented By Suru Saha (EMC/NCEP)

Contributors: Jack Woollen, Daryl Kleist, Dave Behringer, Steve Penny, Xingren Wu, Bob Grumbine, Mike Ek, Jiarui Dong,

Shrinivas Moorthi, Xu Li, Sarah Lu, Yu-Tai Hou, Arun Chawla, Henrique Alves (all EMC)

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Operational System Attribute(s)

System Name Acronym Areal Coverage

Horz Res Cycle Freq

Fcst Length (hr)

Climate Forecast System Reanalysis(operational, coupled atmosphere-ocean-sea-ice-land)

CFSR Global 27km(T574)

6hrs 9-hr coupled guess forecast

NCEP maintains and updates in real time a variety of older Reanalyses, such as R1, R2, plus smaller stand alone (re)analyses (GODAS, LDAS etc).

To discontinue them is next to impossible, which speaks to the need for Reanalyses amongst users.

When talking about “reanalysis” in general, this legacy aspect is included.

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Why System(s) are Operational

Primary stakeholders and requirement driversThe need for Reanalysis is enormous and diverse, such as:

• Provide initial conditions for NCEP models especially hindcasts • Model verification and in-depth process studies• Atmospheric & Oceanic Diagnostic studies, as well as Climate Change Studies• Provide initial conditions for other models (GFDL, CCSM4)• Reanalysis is one vital component of the calibration of forecasts • Basic material for countless empirical studies, including empirical forecasts.

What products are the models contributing to? At NCEP: the CFSv2 forecasts. At CPC: Pretty much 90% of all monitoring that goes on in CPC. Outside NCEP: A variety of outlets (NEI/NCAR) display and distribute our Reanalysis fields

What product aspects are you trying to improve with your development plans? More resolution, higher accuracy, fewer artificial trends Increased availability and greater variety of products.

Top 3 System Performance Strengths• Strength 1: The whole world is using the NCEP Reanalyses• Strength 2: Using satellite radiances directly for the first time in an NCEP Reanalysis• Strength 3: Coupling to the ocean in CFSR (2010) was a unique first step

Top 3 System Performance Challenges • Challenge 1 : Keeping up with constant changes in the observing system.• Challenge 2 : Keeping up with changing CO2 concentrations in the system• Challenge 3 : Maintaining the system in real time going forward

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System Evolution Over the Next 5 Years

Major forcing factors• We need a unified approach to global modeling for all spatial and temporal resolutions for better

management of modeling activities at NCEP. This includes a unified strategy for hindcasts for calibration (which requires initial states in a modern shape for old times, i.e Reanalysis)

Science and development priorities• UGCS Unified Global Coupled System• Atmosphere-Land-Ocean-Seaice-Waves-Aerosol-Ionosphere interactions• Timely new Reanalysis and Reforecast for each implementation

What are you top challenges to evolving the system(s) to meet stakeholder requirements?• Challenge 1 : Using a unified hybrid ensemble approach to DA of the coupled system. Hopefully, this

approach can deal with inhomogeneous data input with strong coupling.• Challenge 2 : Testing the following models within the NEMS framework, to produce the 6-hour guess

forecast: MOM5.1/MOM6 and/or HYCOM for the oceanSIS2/CICE/KISS for sea-ice WAVEWATCH III for wavesNoah-MP for land GOCART for aerosol WAM for ionosphere

• Challenge 3 : Data mining and formatting new datasets for inclusion in the Reanalysis Potential opportunities for simplification going forward

• Unified global DA allows for better use of resources with respect to core / physics / coupling development, but is can we unified on the different scales involved.

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Top 3 Things You Need From the UMAC

1. Help with finding the required resources for:ComputingArchivalDissemination

2. Help with the requirements for sufficient and sustained resources to allow EMC/NCEP to properly complete this huge undertaking

3. Help with shielding the scientists and collaborators from spending valuable timetrying to get the resources, to allow them to do their scientific jobs