To: Phil Jones <p.jones@uea.ac.uk>

Subject: Re: Coverage

Date: Thu, 21 Feb 2008 17:12:22 -0800

Reply-to: santer1@llnl.gov

<x-flowed>

Dear Phil,

A quick question: Do you happen to have a "percentage land coverage

mask" for the HadCRUT3v data? And if so, does this exist as a netCDF file?

With best regards,

Ben

Phil Jones wrote:

>

> Ben,

> Email to Dick reminded me ! Had another phone call and I'd forgotten.

> First file is the coverage.

>

> Second is a program that reads this file - Channel 1.

>

> File is 36 by 72. 5 by 5 degs.

>

> It will start at 85-90N for the 36 subscript.

>

> for 72 it is either dateline or Greenwich.

>

> Cheers

> Phil

>

>

> At 16:53 15/02/2008, you wrote:

>> Dear Dick,

>>

>> I'm forwarding an email that I sent out several days ago. For the last

>> month, I've been working hard to respond to a recent paper by David

>> Douglass, John Christy, Benjamin Pearson, and Fred Singer. The paper

>> claims that the conclusions of our CCSP Report were incorrect, and

>> that there is a fundamental discrepancy between simulated and observed

>> temperature changes in the tropical troposphere. Douglass et al. also

>> assert that models cannot represent the "observed" differential

>> warming of the surface and troposphere. To address these claims, I've

>> been updating some of the comparisons of models and observations that

>> we did for the CCSP Report, now using newer observational datasets

>> (among them NOAA ERSST-v2 and v3). As you can see from the forwarded

>> email, the warming rates of tropical SSTs are somewhat different for

>> ERSST-v2 and v3 - ERSST-v3 warms by less than v2. Do you understand

>> why this is?

>>

>> With best regards, and hope you are well!

>>

>> Ben

>> ----------------------------------------------------------------------------

>>

>> Benjamin D. Santer

>> Program for Climate Model Diagnosis and Intercomparison

>> Lawrence Livermore National Laboratory

>> P.O. Box 808, Mail Stop L-103

>> Livermore, CA 94550, U.S.A.

>> Tel: (925) 422-2486

>> FAX: (925) 422-7675

>> email: santer1@llnl.gov

>> ----------------------------------------------------------------------------

>>

>>

>>

>> X-Account-Key: account1

>> Return-Path: <santer1@llnl.gov>

>> Received: from mail-2.llnl.gov ([unix socket])

>> by mail-2.llnl.gov (Cyrus v2.2.12) with LMTPA;

>> Wed, 13 Feb 2008 18:34:52 -0800

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>> ESMTP id m1E2YMTv008791;

>> Wed, 13 Feb 2008 18:34:52 -0800

>> X-Attachments: LAST_IJC_figure04.pdf

>> X-IronPort-AV: E=McAfee;i="5200,2160,5229"; a="26979778"

>> X-IronPort-AV: E=Sophos;i="4.25,349,1199692800";

>> d="pdf'?scan'208";a="26979778"

>> Received: from dione.llnl.gov (HELO [128.115.57.29]) ([128.115.57.29])

>> by smtp.llnl.gov with ESMTP; 13 Feb 2008 18:34:51 -0800

>> Message-ID: <47B3A8CB.90605@llnl.gov>

>> Date: Wed, 13 Feb 2008 18:34:51 -0800

>> From: Ben Santer <santer1@llnl.gov>

>> Reply-To: santer1@llnl.gov

>> Organization: LLNL

>> User-Agent: Thunderbird 1.5.0.12 (X11/20070529)

>> MIME-Version: 1.0

>> To: santer1@llnl.gov, Peter Thorne <peter.thorne@metoffice.gov.uk>,

>> Stephen Klein <klein21@llnl.gov>,

>> Susan Solomon <Susan.Solomon@noaa.gov>,

>> John Lanzante <John.Lanzante@noaa.gov>,

>> Melissa Free <melissa.free@noaa.gov>,

>> Dian Seidel <dian.seidel@noaa.gov>, Tom Wigley

>> <wigley@cgd.ucar.edu>,

>> Karl Taylor <taylor13@llnl.gov>,

>> Thomas R Karl <Thomas.R.Karl@noaa.gov>, Carl Mears

>> <mears@remss.com>,

>> "David C. Bader" <bader2@llnl.gov>,

>> "'Francis W. Zwiers'" <francis.zwiers@ec.gc.ca>,

>> Frank Wentz <frank.wentz@remss.com>,

>> Leopold Haimberger <leopold.haimberger@univie.ac.at>,

>> "Michael C. MacCracken" <mmaccrac@comcast.net>,

>> Phil Jones <p.jones@uea.ac.uk>,

>> Steve Sherwood <Steven.Sherwood@yale.edu>,

>> Tim Osborn <t.osborn@uea.ac.uk>,

>> Gavin Schmidt <gschmidt@giss.nasa.gov>,

>> "Hack, James J." <jhack@ornl.gov>, peter gleckler

>> <gleckler1@llnl.gov>

>> Subject: Additional calculations

>> References: <200801121320.26705.John.Lanzante@noaa.gov>

>> <478C528C.8010606@llnl.gov> <p06230904c3b2e6b2c92f@[172.17.135.52]>

>> <478EC287.8030008@llnl.gov>

>> <1200567390.8038.35.camel@eld443.desktop.frd.metoffice.com>

>> <7.0.1.0.2.20080117140720.022259c0@llnl.gov>

>> <1200995209.23799.95.camel@eld443.desktop.frd.metoffice.com>

>> <47962FD1.1020303@llnl.gov>

>> In-Reply-To: <47962FD1.1020303@llnl.gov>

>> Content-Type: multipart/mixed;

>> boundary="------------060600010907080200090109"

>>

>> Dear folks,

>>

>> Sorry about the delay in sending you the next version of our

>> manuscript. I decided that I needed to perform some additional

>> calculations. I was concerned that we had not addressed the issue of

>> "differential warming" of the surface and troposphere - an issue which

>> Douglass et al. HAD considered.

>>

>> Our work thus far shows that there are no fundamental inconsistencies

>> between simulated and observed temperature trends in individual

>> tropospheric layers (T2 and T2LT). But we had not performed our

>> "paired trends" test for trends in the surface-minus-T2LT difference

>> time series. This is a much tougher test to pass: differencing

>> strongly damps the correlated variability in each "pair" of surface

>> and T2LT time series. Because of this noise reduction, the standard

>> error of the linear trend in the difference series is typically

>> substantially smaller than the size of the standard error in an

>> individual surface or T2LT time series. This makes it easier to reject

>> the null hypothesis of "no significant difference between simulated

>> and observed trends".

>>

>> In the CCSP Report, the behavior of the trends in the

>> surface-minus-T2LT difference series led us to note that:

>>

>> "Comparing trend differences between the surface and the troposphere

>> exposes potential discrepancies between models and observations in the

>> tropics".

>>

>> So it seemed wise to re-examine this "differential warming" issue. I

>> felt that if we ignored it, Douglass et al. would have grounds for

>> criticizing our response.

>>

>> I've now done the "paired trends" test with the trends in the

>> surface-minus-T2LT difference series. The results are quite

>> interesting. They are at variance with the above-quoted finding of the

>> CCSP Report. The new results I will describe show that the "potential

>> discrepancies" in the tropics have largely been resolved.

>>

>> Here's what I did. I used three different observational estimates of

>> tropical SST changes. These were from NOAA-ERSST-v2, NOAA-ERSST-v3,

>> and HadISST1. It's my understanding that NOAA-ERSST-v3 and HadISST1

>> are the most recent SST products of NCDC and the Hadley Centre. I'm

>> also using T2LT data from RSS v3.0 and UAH v5.2. Here are the tropical

>> (20N-20S) trends in these five datasets over the 252-month period from

>> January 1979 to December 1999, together with their 1-sigma adjusted

>> standard errors (in brackets):

>>

>> UAH v5.2 0.060 (+/-0.137)

>> RSS v3.0 0.166 (+/-0.130)

>> HADISST1 0.108 (+/-0.133)

>> NOAA-ERSST-v2 0.100 (+/-0.131)

>> NOAA-ERSST-v3 0.077 (+/-0.121)

>>

>> (all trends in degrees C/decade).

>>

>> The trends in the three SST datasets are (by definition) calculated

>> from anomaly data that have been spatially-averaged over tropical

>> oceans. The trends in T2LT are calculated from anomaly data that have

>> been spatially averaged over land and ocean. It is physically

>> reasonable to do the differencing over different domains, since the

>> temperature field throughout the tropical troposphere is more or less

>> on the moist adiabatic lapse rate set by convection over the warmest

>> waters.

>>

>> These observational trend estimates are somewhat different from those

>> available to us at the time of the CCSP Report. This holds for both

>> T2LT and SST. For T2LT, the RSS trend used in the CCSP Report and in

>> the Santer et al. (2005) Science paper was roughly 0.13 degrees

>> C/decade. As you can see from the Table given above, it is now ca.

>> 0.17 degrees C/decade. Carl tells me that this change is largely due

>> to a change in how he and Frank adjust for inter-satellite biases.

>> This adjustment now has a latitudinal dependence, which it did not

>> have previously.

>>

>> The tropical SST trends used in the CCSP Report were estimated from

>> earlier versions of the Hadley Centre and NOAA SST data, and were of

>> order 0.12 degrees C/decade. The values estimated from more recent

>> datasets are lower - and markedly lower in the case of NOAA-ERSST-v3

>> (0.077 degrees C/decade). The reasons for this downward shift in the

>> estimated warming of tropical SSTs are unclear. As Carl pointed out in

>> an email that he sent me earlier today:

>>

>> "One important difference is that post 1985, NOAA-ERSST-v3 directly

>> ingests "bias adjusted" SST data from AVHRR, a big change from v2,

>> which didn't use any satellite data (directly). AVHRR is strongly

>> affected in the tropics by the Pinatubo eruption in 1991. If the

>> "bias adjustment" doesn't completely account for this, the trends

>> could be changed".

>>

>> Another possibility is treatment of biases in the buoy data. It would

>> be nice if Dick Reynolds could advise us as to the most likely

>> explanation for the different warming rates inferred from

>> NOAA-ERSST-v2 and v3.

>>

>> Bottom line: The most recent estimates of tropical SST changes over

>> 1979 to 1999 are smaller than we reported in the CCSP Report, while

>> the T2LT trend (at least in RSS) is larger. The trend in the observed

>> difference series, NOAA-ERSST-v3 Ts minus RSS T2LT, is now -0.089

>> degrees C/decade, which is very good agreement with the multi-model

>> ensemble trend in the Ts minus T2LT difference series (-0.085 degrees

>> C/decade). Ironically, if Douglass et al. had applied their flawed

>> "consistency test" to the multi-model ensemble mean trend and the

>> trend in the NOAA-ERSST-v3 Ts minus RSS T2LT difference series, they

>> would not have been able to conclude that models and observations are

>> inconsistent!

>>

>> Here are the observed trends in the tropical Ts minus T2LT difference

>> series in the six different pairs of Ts and T2LT datasets, together

>> with the number of "Hits" (rejections of the null hypothesis of no

>> significant difference in trends) and the percentage rejection rate

>> (based on 49 tests in each case)

>>

>> "Pair" Trend 1-sigma C.I. Hits Rej.Rate

>> HadISST1 Ts minus RSS T2LT -0.0577 (+/-0.0347) 1 (2.04%)

>> NOAA-ERSST-v2 Ts minus RSS T2LT -0.0660 (+/-0.0382) 1 (2.04%)

>> NOAA-ERSST-v3 Ts minus RSS T2LT -0.0890 (+/-0.0350) 0 (0.00%)

>> HadISST1 Ts minus UAH T2LT +0.0488 (+/-0.0371) 28 (57.14%)

>> NOAA-ERSST-v2 Ts minus UAH T2LT +0.0405 (+/-0.0403) 25 (51.02%)

>> NOAA-ERSST-v3 Ts minus UAH T2LT +0.0175 (+/-0.0370) 15 (30.60%)

>> Multi-model ensemble mean -0.0846

>>

>> Things to note:

>>

>> 1) For all "pairs" involving RSS T2LT data, the multi-model ensemble

>> mean trend is well within even the 1-sigma statistical uncertainty of

>> the observed trend.

>>

>> 2) For all "pairs" involving RSS T2LT data, there are very few

>> statistically-significant differences between the observed and

>> model-simulated "differential warming" of the tropical surface and

>> lower troposphere.

>>

>> 3) For all "pairs" involving UAH T2LT data, there are

>> statistically-significant differences between the observed and

>> model-simulated "differential warming" of the tropical surface and

>> lower troposphere. Even in these cases, however, rejection of the null

>> hypothesis is not universal: rejection rates range from 30% to 57%.

>> Clearly, not all models are inconsistent with the observational

>> estimate of "differential warming" inferred from UAH data.

>>

>> These results contradict the "model inconsistent with data" claims of

>> Douglass et al.

>>

>> The attached Figure is analogous to the Figure we currently show in

>> the paper for T2LT trends. Now, however, results are for trends in the

>> surface-minus-T2LT difference series. Rather than showing all six

>> "pairs" of observational results in the top panel, I've chosen to show

>> two pairs only in order to avoid unnecessarily complicating the

>> Figure. I propose, however, that we provide results from all six pairs

>> in a Table.

>>

>> As is visually obvious from the Figure, trends in 46 of the 49

>> simulated surface-minus-T2LT difference series pairs are within the

>> 2-sigma confidence intervals of the NOAA-ERSST-v3 Ts minus RSS T2LT

>> trend (the light grey bar). And as is obvious from Panel B, even the

>> Douglass et al. "sigma{SE}" encompasses the difference series trend

>> from the NOAA-ERSST-v3 Ts/RSS T2LT pair.

>>

>> I think we should show these results in our paper.

>>

>> The bottom line: Use of newer T2LT datasets (RSS) and Ts datasets

>> (NOAA-ERSST-v3, HADISST1) largely removes the discrepancy between

>> tropical surface and tropospheric warming rates. We need to explain

>> why the observational estimates of tropical SST changes are now

>> smaller than they were at the time of the CCSP Report. We will need

>> some help from Dick Reynolds with this.

>>

>> With best regards,

>>

>> Ben

>> ----------------------------------------------------------------------------

>>

>> Benjamin D. Santer

>> Program for Climate Model Diagnosis and Intercomparison

>> Lawrence Livermore National Laboratory

>> P.O. Box 808, Mail Stop L-103

>> Livermore, CA 94550, U.S.A.

>> Tel: (925) 422-2486

>> FAX: (925) 422-7675

>> email: santer1@llnl.gov

>> ----------------------------------------------------------------------------

>>

>>

>>

>

> Prof. Phil Jones

> Climatic Research Unit Telephone +44 (0) 1603 592090

> School of Environmental Sciences Fax +44 (0) 1603 507784

> University of East Anglia

> Norwich Email p.jones@uea.ac.uk

> NR4 7TJ

> UK

> ----------------------------------------------------------------------------

>

>

>

> ------------------------------------------------------------------------

>

> program growlandmergeetc

> dimension lnd(72,36),nlnd(72,36),ivsst(72,36),jcov(72,36)

> dimension icmb(72,36),alcov(72,36),ascov(72,36),iysst(72,36)

> dimension isdvar(72,36,12),neigsd(72,36,12)

> dimension iorigt(72,36),icount(72,36)

> dimension ash(12),anh(12),ashp(12),anhp(12)

> dimension np(12),npch(12),npinf(12),npchan(12),npsst(12)

> rad=57.2958

> ir=13

> c calculate maximum % coverage of hemisphere in cos units

> xnh=0.0

> do 20 j=1,18

> w=cos((92.5-j*5)/rad)

> do 19 i=1,72

> 19 xnh=xnh+w

> 20 continue

> c read in land fraction in %

> read(1,21)i1,i2

> 21 format(2i6)

> do 22 j=1,36

> 22 read(1,23)(jcov(i,j),i=1,72)

> 23 format(72i6)

> c set coverage of land to % of at least 25% and less than 75%

> c ocean percent is then simply the rest

> do 24 j=1,36

> do 24 i=1,72

> alcov(i,j)=0.01*jcov(i,j)

> if(alcov(i,j).le.24.9)alcov(i,j)=25.0

> if(alcov(i,j).ge.75.1)alcov(i,j)=75.0

> ascov(i,j)=100.0 - alcov(i,j)

> 24 continue

> c read in the sd of the land only datset (var corected) to assess

> c whether the neighbour check can legitimately correct values

> do 901 k=1,12

> read(4,27)ii

> do 902 j=1,36

> 902 read(4,29)(isdvar(i,j,k),i=37,72),(isdvar(ii,j,k),ii=1,36)

> 901 continue

> c read in neighbouring sd calculated from at least 4 of the

> c neigbouring 8 5 degree squares around each grid box

> do 903 k=1,12

> read(18,27)ii

> do 904 j=1,36

> 904 read(18,29)(neigsd(i,j,k),i=37,72),(neigsd(ii,j,k),ii=1,36)

> 903 continue

> c skip the first 19 years of the variance corrected land data

> c as the variance corrected SST data only starts in

> c also skip the first 19 years of the original gridded temps

> c so later can check the number of stations available per gridbox

> c per month

> do 25 k=1851,1869

> do 26 kk=1,12

> read(2,27)i1,i2

> 27 format(2i5)

> read(ir,27)i1,i2

> do 28 j=1,36

> 28 read(2,29)(lnd(i,j),i=37,72),(lnd(ii,j),ii=1,36)

> 29 format(12i5)

> do 128 j=1,36

> 128 read(ir,29)(iorigt(i,j),i=37,72),(iorigt(ii,j),ii=1,36)

> do 129 j=1,36

> 129 read(ir,29)(icount(i,j),i=37,72),(icount(ii,j),ii=1,36)

> 26 continue

> 25 continue

> c read in the land and sst data (both variance corrected)

> c reading in the land allow for the greenwich start of the land

> c and the dateline start for the SST. Output is from the dateline

> do 31 k=1870,1999

> ashy=0.0

> anhy=0.0

> if(k.ge.1901)ir=14

> if(k.ge.1951)ir=15

> if(k.ge.1991)ir=16

> if(k.ge.1994)ir=17

> do 32 kk=1,12

> npch(kk)=0

> npchan(kk)=0

> np(kk)=0

> npinf(kk)=0

> npsst(kk)=0

> c read in the original gridded land to get the station count

> c per grid box

> read(ir,27)i1,i2

> do 131 j=1,36

> 131 read(ir,29)(iorigt(i,j),i=37,72),(iorigt(ii,j),ii=1,36)

> do 132 j=1,36

> 132 read(ir,29)(icount(i,j),i=37,72),(icount(ii,j),ii=1,36)

> c read in the variance corrected land

> read(2,27)i1,i2

> write(7,27)kk,k

> do 33 j=1,36

> 33 read(2,29)(lnd(i,j),i=37,72),(lnd(ii,j),ii=1,36)

> c copy lnd array to nlnd so that the growing doesn't use already

> c infilled values

> do 34 j=1,36

> do 34 i=1,72

> 34 nlnd(i,j)=lnd(i,j)

> c read in sst data

> read(3,21)i1,i2

> do 35 j=1,36

> 35 read(3,23)(ivsst(i,j),i=1,72)

> c check land for extremes and fill in gaps (only one grid box away

> c provided there are at least 4 of the 8 surrounding boxes)

> do 41 j=1,36

> j1=j-1

> j2=j+1

> if(j1.eq.0)j1=1

> if(j2.eq.37)j2=36

> do 42 i=1,72

> sum=0.0

> nsum=0

> i1=i-1

> i2=i+1

> do 43 jj=j1,j2

> do 44 ii=i1,i2

> iii=ii

> if(iii.eq.73)iii=1

> if(iii.eq.0)iii=72

> if(jj.eq.j.and.iii.eq.i)go to 44

> if(lnd(iii,jj).eq.-9999)go to 44

> sum=sum+lnd(iii,jj)

> nsum=nsum+1

> 44 continue

> 43 continue

> if(lnd(i,j).ne.-9999)np(kk)=np(kk)+1

> if(nsum.le.3)go to 47

> sum=sum/nsum

> ndep=sum+0.5

> if(sum.lt.0.0)ndep=ndep-1

> nval=ndep

> if(lnd(i,j).eq.-9999)go to 46

> npch(kk)=npch(kk)+1

> ndep=lnd(i,j)-nval

> if(neigsd(i,j,kk).eq.-9999)go to 47

> if(iabs(ndep).le.225)go to 47

> if(iabs(ndep).lt.neigsd(i,j,kk)*2.0)go to 47

> if(icount(i,j).ge.2)go to 47

> nlnd(i,j)=nval

> npchan(kk)=npchan(kk)+1

> 48 write(6,202)k,kk,j,i,nval,lnd(i,j),ndep,isdvar(i,j,kk),

> >neigsd(i,j,kk),nlnd(i,j),nsum,icount(i,j),iorigt(i,j)

> 202 format(4i4,9i6)

> go to 47

> 46 nlnd(i,j)=nval

> npinf(kk)=npinf(kk)+1

> 47 continue

> 42 continue

> 41 continue

> c merge with marine using the weighting factors

> do 51 j=1,36

> do 52 i=1,72

> wx=0.0

> xx=0.0

> if(nlnd(i,j).eq.-9999)go to 55

> wx=wx+alcov(i,j)

> xx=xx+alcov(i,j)*nlnd(i,j)

> 55 if(ivsst(i,j).eq.-32768)go to 56

> wx=wx+ascov(i,j)

> xx=xx+ascov(i,j)*ivsst(i,j)

> 56 if(wx.ge.0.001)go to 59

> icmb(i,j)=-9999

> go to 57

> 59 aa=xx/wx

> ia=aa+0.5

> if(xx.lt.0.0)ia=ia-1

> icmb(i,j)=ia

> c writing out the land/sst merging checking when both are present

> c if(wx.ge.99.9)write(6,203)kk,j,i,ia,nlnd(i,j),ivsst(i,j),

> c >wx,alcov(i,j),ascov(i,j)

> c 203 format(6i6,3f7.1)

> 57 continue

> 52 continue

> 51 continue

> c write out the new merged file

> do 53 j=1,36

> 53 write(7,54)(icmb(i,j),i=1,72)

> 54 format(12i5)

> c calculate the hemispheric averages

> anh(kk)=0.0

> ash(kk)=0.0

> ashp(kk)=0.0

> anhp(kk)=0.0

> wx=0.0

> xx=0.0

> do 61 j=1,18

> w=cos((92.5-j*5.0)/rad)

> do 62 i=1,72

> if(icmb(i,j).eq.-9999)go to 62

> wx=wx+w

> xx=xx+w*icmb(i,j)

> 62 continue

> 61 continue

> anh(kk)=xx*0.01/wx

> anhp(kk)=wx*100.0/xnh

> wx=0.0

> xx=0.0

> do 63 j=19,36

> w=cos((j*5.0-92.5)/rad)

> do 64 i=1,72

> if(icmb(i,j).eq.-9999)go to 64

> wx=wx+w

> xx=xx+w*icmb(i,j)

> 64 continue

> 63 continue

> ash(kk)=xx*0.01/wx

> ashp(kk)=wx*100.0/xnh

> anhy=anhy+anh(kk)

> ashy=ashy+ash(kk)

> 32 continue

> anhy=anhy/12.0

> ashy=ashy/12.0

> write(8,89)k,anh,anhy

> 89 format(i4,12f6.2,f7.2)

> write(8,90)k,anhp

> 90 format(i4,12f6.0)

> write(9,89)k,ash,ashy

> write(9,90)k,ashp

> write(10,91)k,np

> write(10,91)k,npch

> write(10,91)k,npchan

> write(10,91)k,npinf

> write(10,92)

> 92 format(/)

> 91 format(i4,12i6)

> 31 continue

> stop

> end

>

>

--

----------------------------------------------------------------------------

Benjamin D. Santer

Program for Climate Model Diagnosis and Intercomparison

Lawrence Livermore National Laboratory

P.O. Box 808, Mail Stop L-103

Livermore, CA 94550, U.S.A.

Tel: (925) 422-2486

FAX: (925) 422-7675

email: santer1@llnl.gov

----------------------------------------------------------------------------

</x-flowed>

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