Mechoso. Tuesday, June 18, 2013

Transcription

1 June 19 ETOS telecon Mechoso

2 progress limited to website we should at least suggest metrics progress ultimately, a white paper and journal submission some progress good awareness of european campaigns thanks to Peter Brandt

3 june 19, larger etos telecon agenda 1. update since last telecon/meeting in Dec a refined understanding of the SST biases - new european oceanographic field campaigns - focus on the Atlantic 2. identify opportunities for contribution by larger group using ppt as a template for a white paper

4 view developed through smaller telecons 1) sst biases in the Atlantic have a critical oceanographic contribution significantly improved models show less of an improvement in Atlantic sst biases than Pacific (notwithstanding that cmip5 sst biases have improved relative to cmip3 in both Pacific&Atlantic, and cloud-sst feedbacks are evident, but not enough to explain/remove biases)

5 this can be seen within the ncar model, which improved its deep convection depiction significantly from CCSM3->CCMS4, with little change in SST biass we need a similar plot for CESM/ CAM5, which also improved its shallow clouds/boundary layer depiction Gent et al., 2011

6 cmip5 Q: do corresponding, multi-model-mean plots of cmip3 and cmip5 biases also show this? I think so but would be good to get a similar plot for both cmip3/ cmip5. Ingo?Tomas? T. Toniazzo

7 figures on google site do not yet appear on the us clivar site

8 and because cloud distribution in cmip5 and amip5 ncar model is similar (so cloud-sst feedback, apparent as cmip CA<amip CA, is a secondary explanation for the SST bias) medeiros (is CESM1/CAM5=CMIP5?) B. Medeiros turned around, this also means the SST-cloud feedback cannot be the prime explanation for the too-low offshore cloud, or, as BM puts it, a too-coastal transition region

9 2) the Atlantic sst bias is most pronounced in the southeast Atlantic (same plot as Gent fig. 1 but better color scale)

10 note that in coastal region where main SST bias occurs, model clouds do better (supporting an oceanographic explanation for the sst bias), but, cloud-sst feedback also apparent (as also ucla) B. Medeiros

11 orography: Doi helps with Pacific, not so much S. Atlantic impact of improved resolution: ocean little improvement temporal: Schneider reduces precip bias, worsens SST bias ee also williamson paper: convnc oes less work if delta t shortens discuss w/ Justin Small

12 3) the connection between the equatorial and southeast Atlantic sst biases is unclear - coastal sst biases most pronounced south of ABF -equatorial biases have link to amazonian convection also a link to the west african monsoon

13 - south of the angola-benguela front, the coastal wind stress is too weak, and the ABF too far south. one hypothesis: angola current advects south underneath ABF, then upwells as warm water. hypothesized by whom? P. Chang? T. Tomiazzo? both? others? coastal Kelvin wave? cmip5, P. Chang

14 notorious atlantic sst gradient remains

15 so presumably the same mechanism is at play Richter&Xie 2008 Chang et al cmip3; Ingo have you redone this w/ cmip5? Amazon too little rain -> easterly winds either too weak or westerly -> not enough upwelling along eastern equator, thermocline too diffuse (ccsm4 shows some improvement)

16 3) the connection between the equatorial and southeast Atlantic sst biases is unclear but hypothesized to exist: is a connection necessary for the SEA sst biases to be climatically relevant? (are both the equatorial and SEA sst biases most apparent in JJA?)

17 4) better clouds will still contribute to lessened SST biases cloud-sst feedback obvious in cmip-amip comparisons especially near coast an issue remains the too-low cloud cover, too-near coastal transition in cam5: perhaps too much daytime decoupling still (Medeiros et al. 2012) (not true in cam4 which had worse BL clouds)

18 new funded field campaigns - Southwest African Coastal Upwelling Study (SACUS; PI Peter Brandt; Germany-funded; ) - Enhancing PREdiction of Tropical Atlantic ClimatE and its impact (PREFACE; Coordinator Noel Keenlyside; EUfunded; (?)) -Ecosystem Approach to the management of fisheries and the marine environment in west-african waters (AWA; France-Germany-West Africa) - remove this is north of the eq. -Dynamics-aerosol-chemistry-cloud interactions in West Africa (DACCIWA; Peter Knippertz Coordinator) -GOAmazon (DOE; PI Scot Martin). (NSF complement not funded)

19 '"#+ ("#+ D:, R.9 D0676:102E6.6:5, 90/5=0901 F4.,,01 10F45G01 H4:109E ),-.,/ ),-.,/01 789:;6092<5=09.>0 90/5= :;609 *IJEI9;./0 <5=09.>0 D559:,>E 10F45G01 F4.,,01 H4:109E 90/5=0901 D0676:102E6.6:5, MJ:1Q., <565,5I N.>5E 85I.4. "# *.52C5P0 ("#* T. PIRATA/PREFACE NI.,1. *.4=.159 '"#* SACUS L:52102S.,0:95 $.4=:E2B.G &"#*!"#$ %"#$ &"#$ '"#$ ("#$ "# ("#) '"#) P. Brandt

20 several Atlantic atmospheric campaigns at proposal development stage; all due late 2013/early 2014 ORACLES (NASA, Jens Redemann-PI) CLARIFY (UK, Jim Haywood) ONFIRE (NSF, Zuidema) share objectives to document & understand smoke-stratus interactions. these are likely of secondary relevance to equatorial SST biases, with surface aerosol forcing most pronounced near coast. documenting cloud structure and surface radiation budget is a common interest w/ oceanographic campaigns

21 we need to come up with metrics, identify further useful US contributions progress limited to website progress ultimately, a white paper leading to a peer-reviewed pub Europeans taking lead w/ oceanographic campaigns

22 (doable by us) metrics atlantic sst biases 1. equatorial SST gradient vs u Richter 2. ABF location vs sst Chang 3. seasonal cycle in cold tongue sst & meridional wind stress (mitchell&wallace, 1992) is anyone looking at this? De Szoeke&Xie, 2008

23 clouds de Szoeke et al. 2012, cmip3, S, W 3. surface shortwave cloud forcing vs. ca/lwp/lts, KH box, sep&sea UCLA-Miami-Medieros 4. seasonal cycle Zuidema Bellomo&Zuidema (can seasonal cycle be displayed as a taylor diagram? std. dev. of amplitude of each year s seasonal cycle vs temporal corr? std. dev. about annual mean vs temporal corr?) many cmip5 models have isccp&calipso simulators but not modis. see pincus, kay papers

24 other suggested metrics - annual cycle in thermocline - atlantic warm pool after all this we can opine as a group: do the same models perform well/poorly?

25 request to group: if you see something you think important missing, send me a slide+couple sentence writeup on it if you would like to see another metric included, identify the metric & try to contribute the plot

26 a question we should have an answer to for the US CLIVAR Summit: how can US best contribute? observation that augment european field campaigns: interrogate atmospheric vertical structure: 6 or 8x/daily soundings of atlantic stratus spectral irradiance measurements on new pirata buoy support modeling activities of main SEA SST bias region + connection to equator