**[February 13 2008 Attribution Conf. Call Summary:]{.underline}**

***Items for Next cc, and Research Opportunities***

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Participants:

T. Mitchell JJ. OBrien

A. Kumar J. Kemple

J. Schaefer C. Miller

R. Heim H. Jain

M. L'Heureux D.LaComte

M. McPhaden T. Knutson

M. Hoerling K. Weickman

M. Halpert J. Perlwitz

T. Xu T. Zhang

Q. Xiaowei D. Sun

J. Eischeid G. Lau

D. Easterling H. Brooks

R. Webb K. Wolter

The CSI Team focused on the following issues of current attribution:

1.  ***Rapid Response to CPO Request for Cause(s) of '08 US Tornado
    Outbreak***

2.  ***Explaining the 2007 US Annual Precipitation Extremes***

3.  ***Diagnosing North American Impacts of La Niña: OND 2007***

4.  ***Attributable Causes for the 2007 Record Global Land
    Temperatures.***

A powerpoint contained some current analyses being conducted by the CSI
team. Briefly, this included dedictated atmospheric GCM simulations
relevant to current conditions as a primary tool for addressing items 2)
-- 4), coupled GCM simulations from CMIP3 archive to address 4), and
historical observations of ocean and atmosphere conditions during La
Niña regarding all items.

**[Main points on attribution:]{.underline}**

1.  Expert assessment of the climate conditions relevant to tornado
    environment performed. In addition to the CSI Team contributors,
    enlisted the expertise of scientists from NSSL.

> **\-\-\-\-- Fact Sheet of Q&A on 2008 Tornado Season**
>
> *complete in timely fashion for NOAA CPO to include in 24 February*
>
> *Congressional Briefing material for NOAA Administrator and Deputy.*

2.  Attribution for the 2007 extreme annual US pcpn departures.

> \-\-\--**Attribution Report Submitted to BAMS "2007: State of Climate
> Report"**
>
> *the report is under review, and a draft copy is posted on the CSI web
> portal*

3.  The observed *pattern* of Oct-Nov 2007 US seasonal anomalies in pcpn
    were shown to be only modestly consistent, at best, with the
    historical La Niña composite pattern of 8 events (yr-0) post 1950.
    For sfcT, observed warmth in many states (especially the East) was
    inconsistent with historical La Niña composites for which no
    significant sfcT signal exists during OND east of the Mississippi.

> As during prior seasons of 2007, strong positive height anomalies over
> the US in OND were shown to be linked with a zonal band of high
> pressure throughout the midlatitudes. This appeared to be a major
> contributor to the elevated US warmth, though not a feature seen in
> the historical composite based on Reanalysis data.
>
> AGCM simulations indicate that the midlatitude belt of
>
> anomalously high pressure is consistent with the global SST
>
> conditions of OND 2007. The support for such an attribution came
>
> from multi-model AGCM runs forced with global SSTs...a 150-member
>
> ensemble, whose mean response consisted of such midlatitude
> anticyclones
>
> (though the ensemble mean signal was ½ amplitude the observed
> anomalies)
>
> Additional runs forced only with the East Pacific cold SSTs of '07
> failed to
>
> generate such a pattern, and likewise yielded a much weaker US warmth.
> This
>
> supported a view that non-ENSO region SSTs were an important factor in
> the
>
> SST- forced signal of SON 2007.
>
> \-\-\-- **realtime attribution item to pursue for next CSI meeting**
>
> *[Carry-over from prior meeting]{.underline}: diagnose the
> time-evolution of the zonal*
>
> *mean tropospheric circulation pattern during the prior 12 months in
> order*
>
> *to better understand its origins and the prospects for its
> persistence.*
>
> *Update AGCM 150-member ensemble thru calendar 2007.*
>
> \-\-\-- **research opportunity**
>
> *diagnose the role of the unusally warm extratropical SSTs (an index
> of the*
>
> *Natl SST is the highest in atleast 60 years) in forcing recent
> climate*
>
> *conditions. What has been the role of the record (since 1948) warm
> Natl*
>
> *SSTs?*

4.  Global land surface temperatures for 2007 were the warmest on record
    (since 1880). A model-based assessment to diagnose contributing
    factors reveals that global SST conditions in 2007 alone could not
    explain the record warmth.....no single member of a 150-member AGCM
    ensemble for 2007 yielded warmth as large as oberved. Analysis of
    greenhouse gas forced CMIP runs indicates that anthropogenic forcing
    was likely a principal factor raising land temperatures in
    2007.....several runs of a 48-member ensemble yielded 2007 warmth
    greater than observed.

> \-\-\-\-- **Attribution Report to be completed and submitted to BAMS
> "2007:**
>
> **State of Climate Report"**
>
> *the report is to be posted on the CSI web portal*
>
> \-\-\-- **research opportuity**
>
> *Global ocean GHG-forced SST anomalies of 2007 appreciably warmer*
>
> *than observed. What consequence for global land surface warmth?*
>
> *Consider performing additional AGCM simulatons forced with the CMIP-*
>
> *ensemble mean 2007 SST anomalies.*
>
> *Assess the role of observed SSTs and GHG forcing of global land
> surface*
>
> *Temperatures for each year during 2001-2007.*

**[Progress in dissemination of attribution information to
date:]{.underline}**

The CSI Team has taken advantage of several opportunities for timely
distribution of attribution information.

1.  The Annual State of the Climate Report.

> \-\-\-\-- ***regarding*** ***contribution for 2008 report***
>
> Richard Heim of NCDC is now reviewing the NOAA CSI Teams submitted
> report on 2007 US extreme precipitation departures.
>
> The NOAA CSI team is in the process of submitting a second report on
> the record 2007 global land surface temperatures.
>
> ***\-\-\-- routine (seasonal) attribution discussion***
>
> A major focus of the current intense attribution project is US
> conditions during winter/spring 2007/08, especially regarding the role
> of La Niña. We expect to provide a synthesis of understanding of the
> seasonal observed and CPC predicted conditions in '08.