From: Ben Santer To: Phil Jones Subject: Re: Coverage Date: Thu, 21 Feb 2008 17:12:22 -0800 Reply-to: santer1@llnl.gov 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: >> 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 >> Received: from smtp.llnl.gov (nspiron-3.llnl.gov [128.115.41.83]) >> by mail-2.llnl.gov (8.13.1/8.12.3/LLNL evision: 1.6 $) with >> 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 >> 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 , >> Stephen Klein , >> Susan Solomon , >> John Lanzante , >> Melissa Free , >> Dian Seidel , Tom Wigley >> , >> Karl Taylor , >> Thomas R Karl , Carl Mears >> , >> "David C. Bader" , >> "'Francis W. Zwiers'" , >> Frank Wentz , >> Leopold Haimberger , >> "Michael C. MacCracken" , >> Phil Jones , >> Steve Sherwood , >> Tim Osborn , >> Gavin Schmidt , >> "Hack, James J." , peter gleckler >> >> Subject: Additional calculations >> References: <200801121320.26705.John.Lanzante@noaa.gov> >> <478C528C.8010606@llnl.gov> >> <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 ----------------------------------------------------------------------------