[cam-users] CGD Forums

Sat Jan 15 09:00:00 MST 2005

Dear cam-users, 

As you requested, here is the latest digest of messages posted on CGD Forums forums. Please come and join the discussion!

<<  New Job Opening at NCAR for atmospheric scientist, http://bb.cgd.ucar.edu//viewtopic.php?t=94 >>

PosterpjrPostedFri Jan 14, 2005 7:27 pm MST, http://bb.cgd.ucar.edu//viewtopic.php?p=274#274
Message: Dear AMWG.
 
 I am appending an announcement for a job opportunity at NCAR highly
 relevant to CAM and the AMWG. This opening is for the AMWG liason
 position that Jim McCaa formerly held.
 
 Please advertise it as widely as possible within the community, and
 let me know if you are aware of promising candidates.
 
 We have changed the position from an Associate Scientist category to
 a Project Scientist category, and increased the emphasis on the
 scientific aspects of the position. The previous position included
 more support for infrastructure.
 
 Feel free to contact me with questions.
 
 Regards
 
 Phil Rasch
 
 --
 Phil Rasch, Climate Modeling Section, National Center for Atmospheric Research
 Mail --&gt; P.O. Box 3000, Boulder CO 80307
 Shipping --&gt; 1850 Table Mesa Dr, Boulder, CO 80305
 email: pjr at ucar.edu, Web: http://www.cgd.ucar.e!
 du/cms/pjr Phone: 303-497-1368, FAX: 303-497-1324
 
 --------------------------------------------------------------------------
 
 See:
 http://www.fin.ucar.edu/hr/careers/uco.cfm?do=jobDetailExt&amp;job_ID=415
 
 Project Scientist I
 Job Category: Scientific
 Division/Program: CGD
 [Job #5001, at Mesa Lab]
 
 
 Please Note:
 
 This is a full-time replacement position. Initial consideration will
 be given to applications received prior to Friday, February 4,
 2005. Thereafter, applications will be reviewed on an as-needed basis.
 
 NCAR - Climate and Global Dynamics Division (CGD)
 
 Basic Job Function:
 
 As a member of the CCSM Atmospheric Model Working Group (AMWG), this position will combine scientific research with the day-to-day
 coordination and support of the Community Climate System Model (CCSM) atmospheric model development activities. A major !
 responsibility of the position will be the coordination of mod!
 el devel
opment activities conducted under the auspices of the AMWG, a 100+ person activity.
 
 Approximately half of the time for the position will be devoted to
 scientific research directed towards improving some aspect of the
 Community Atmospheric Model (CAM). Preferred areas of focus are
 clouds, boundary layer processes, aerosols, or formulations of
 atmospheric dynamics and transport relevant to CAM.
 
 The other half of the position will facilitate the goal of a
 community-developed atmospheric model. This position will serve the
 role of principal contact and coordinator for scientific investigators
 pursuing improvements to the representation of physical and dynamical
 processes in the NCAR CCSM atmospheric component. The position will
 provide general oversight and support for the scientific development,
 use, analysis, and modification of the CCSM atmospheric component.
 
 Priorities will be !
 determined in consultation with the Head of the
 NCAR Climate System Model, and co-chairs of the CCSM Atmospheric Model Working Group. This position will report to the local co-chair. The
 incumbent is expected to operate with a significant degree of
 independence.
 
 Duties Include:
 
 Under general guidance, conducts independent and collaborative
 research in areas related to the role of the atmosphere in the climate
 system. Analyzes observational datasets to improve understanding of a
 particular set of processes in the atmosphere. Analyzes model output
 to assess the degree of fidelity of those processes in the
 model. Develops new diagnostic procedures for understanding model and
 atmospheric processes. Revises or replaces process representations in
 model with improved formulations.
 
 Participates in the design and implementation of enhancements to
 atmospheric modeling and analysis!
 tools. Works with moderate
 supervision to modify the CC!
 SM atmos
pheric model for specific
 scientific applications. This work may include the incorporation of
 new numerical methods, parameterizations of physical processes, or the
 creation of model configurations designed to address specific
 scientific questions. Runs numerical experiments including the
 preparation and manipulation of input and output datasets.
 
 Consults with the CCSM SSC Chair and CCSM AMWG Co-chairs regarding
 modification priorities for the CCSM atmospheric component. Helps
 oversee the orderly incorporation and testing of proposed changes to
 the CCSM atmospheric model formulation. Helps coordinate the extension
 of diagnostic and testing procedures as needed to ensure a thorough
 evaluation of proposed changes. Consults with the CCSM software
 engineering group on general directions for model development.
 
 Provides advice and direction about CCSM AMWG activities in response
 to qu!
 estions and concerns raised by members of the CCSM community. The incumbent must be able to communicate complex scientific and
 computational ideas to all levels of participants in the CCSM
 community.. Participates in the writing of formal reports on working
 group progress, and in the writing of requests for computational
 resources.
 
 Documents experimental and diagnostic procedures. Organizes and
 maintains a comprehensive database of simulation output and
 analyses. Makes this information available to the broader community
 via the World Wide Web. Helps develop, implement, and maintain a CCSM AMWG outreach to the scientific and non-scientific communities through comprehensive Web tools.
 
 Helps manage the CCSM AMWG computer allocation, adding users, and
 making appropriate adjustments based on evolving scientific and
 computational needs, such as optimal use of the AMWG allocation during
 specific !
 periods of time.
 
 
 Requirements Include:
<br!
 />
 
 Education and Experience:
 
 Ph.D. or equivalent in atmospheric, ocean or related Earth sciences;
 plus two years' of relevant experience in at least one of these areas:
 Demonstrated experience in working with large scientific computer
 programs. Demonstrated experience in developing complex simulation
 models. Demonstrated experience in writing appropriate for scientific
 peer reviewed journals and documentation for simulation models and
 experiments.
 
 
 Knowledge, Skills and Abilities:
 
 Demonstrated understanding, through published or academic work, of
 modeling complex, geophysical processes. Demonstrated knowledge of
 the physical and mathematical basis of atmospheric general circulation
 models. Demonstrated experience in designing and implementing
 reliable, portable, and efficient Fortran modules for complex
 geophysical systems. Demonstrated knowledge of the U!
 NIX operating
 system and its variants, including skill in writing shell scripts.
 Knowledge of graphical analysis tools (e.g., NCL, ferret, IDL)
 Knowledge of data analysis methodologies for global atmospheric and
 climate phenomena. Effective oral and written communication skills.
 Ability to assess priorities and manage tight deadlines. Knowledge of
 web-based communication.
 
 
 Options for applying for this position:
 
 Online:
 Apply through WebHire
 http://www.fin.ucar.edu/hr/careers
 
 Standard Mail:
 
 Send your paper resume to:
 UCAR Human Resources
 3065 Center Green Drive
 Boulder, Colorado 80301

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

<<  Spring AMWG meeting announcement, http://bb.cgd.ucar.edu//viewtopic.php?t=93 >>

PosterpjrPostedFri Jan 14, 2005 5:11 pm MST, http://bb.cgd.ucar.edu//viewtopic.php?p=273#273
Message: Greetings to the AMWG,
<br />
<br />We would like to announce the spring AMWG workshop. The meeting will take place on March 1-3, at the NCAR ML in Boulder Colorado. Details
<br />on hotel accommodation etc. will be forthcoming.
<br />
<br />Many of the remaining biases in CAM manifest themselves when coupled
<br />to the other model components. We believe the time is right to begin a
<br />discussion with the Ocean Model Working Group (OMWG) on topics of
<br />mutual interest to both groups and therefore have planned two "joint
<br />sessions" with a focus on the role of ocean-atmosphere interactions in
<br />influencing phenomena of interest to both groups. We are thinking in
<br />particular of:
<br />
<br />
<br />1) ENSO phenomena
<br />2) the influence of ocean atmosphere interactions on boundary layer,
<br />   and convective processes on time scales from the diurnal through
<br />   the MJO
<br />3) double ITCZ
<br />
<br />
<br />As noted below, we are also!
  trying to maintain adequate room for
<br />discussion of non-ocean related science at the meeting.
<br />
<br />To accommodate the extra sessions, and still allow an opportunity for
<br />the introspective discussion, and presentations that normally take
<br />place, we are allocating a much as 3 days for the meeting. The agenda
<br />will be refined as we see the level of interest in the topics.
<br />
<br />Here is our current plan:
<br />
<br />day 1: 
<br />
<br />AM: Joint meeting with Ocean WG. Presentation of current
<br />                model strengths and weaknesses. Discussion of how to
<br />                make progress on the improvements. Identification of
<br />                points each WG should consider separately over the
<br />                next 2 days.
<br />
<br />       PM:   AMWG and OMWG meet separately.  AMWG will do  
<br />                something like:
<br />                1) start internal discussion about how progress can be
<br />     !
               made 
<br />                2) form breakout gro!
 ups focu
sing on Ocean/Atm problems
<br />
<br />
<br />day 2:
<br />
<br /> AM: AMWG meets in breakout of groups focusing on
<br />                 atmospheric problems. These groups (convection,
<br />                 cloud physics,  data assimilation, dynamics,
<br />                 aerosols/chemistry, large-scale clouds,
<br />                 and variability) were set up as last summer's AMWG. We
<br />                 will review the strategies they established then
<br />                 and begin to implement them at this meeting.
<br />     
<br />   PM:  AMWG meets as a whole for presentations on current
<br />                work. Please submit an abstract if you would like
<br />                to present a report. Oral and/or poster sessions
<br />                are planned.
<br />
<br />
<br />day 3: 
<br />AM: AMWG and OMWG meet as a whole, to provide feedback to
<br />                each other and agree on tactics for the future.
<br />
<br />          PM: AMWG mee!
 ts as a whole for more presentations, a
<br />                review of day-1 breakouts, and brief discussion about
<br />                how to respond to OMWG and strategy for the future.
<br />
<br />
<br />Please respond by 7 February (the sooner the better!) as to your plans
<br />on attending the meeting and provide us with an abstract if you would
<br />like to make a presentation. Please let us know also if there are any
<br />topics or issues within the general framework planned for the meeting
<br />that you would like to be discussed.
<br />
<br />Please send all communications to pjr at ucar.edu and lydia at ucar.edu.
<br />
<br />Please use a subject line that includes the words "SPRING 2005 AMWG MEETING"
<br />
<br />Regards,
<br />
<br />Phil and Leo

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

<<  Why is CAM slower in CCSM3.0 than in CCSM2.0.1?, http://bb.cgd.ucar.edu//viewtopic.php?t=92 >>

PosterguscorreaPostedFri Jan 14, 2005 3:59 pm MST, http://bb.cgd.ucar.edu//viewtopic.php?p=272#272
Message: Hello CAM maintainers and user list
 
 I posted this on the CCSM list, but maybe it is appropriate to post it here also,
 since the questions are related to CAM's performance.
 
 I installed CCSM2.0.1 and CCSM3.0 on our beowulf cluster at LDEO.
 Somehow the new version runs about 47% slower than the old one.
 A 1-year t42_gx1v3 full dynamic run, using 32 cpus,
 takes about 21h 13min on CCSM2.0.1, but lingers for 31h 15min on CCSM3.0,
 using the same cpu/component distribution.
 
 FYI, our cluster nodes are Dual 1.2GHz Athlon, 1GB ram, with Myrinet 2000,
 Linux kernel 2.4.18, MPICH 1.2, Gnu and PGI 5.2-4 compilers, and PBS.
 
 The timing data provided by the coupler suggest that the atmosphere component 
 "cam" is much slower in CCSM3.0 than it was in CCSM2.0.1.
 Here is a comparison of timers "t25" on CCSM3.0 and "t26" on CCSM2.0.1, 
 which correspond to the atm -&gt; cpl commu!
 nication:
 
 CCSM3.0 cpl log file : (shr_timer_print) timer 27: 8760 calls, 70403.943s, id: t25
 CCSM2.0.1 cpl log file: (shr_timer_print) timer 27: 8760 calls, 47996.592s, id: t26
 
 Cam's MPI communication was significantly modified in CCSM3.0.
 Would this be the reason for the drop in speed?
 
 Cam's timing files suggest that this is the case.
 They show that, compared to CCSM2.0.1:
 
 1. The total time "cam" takes between send/recv to/from the coupler increased by about 67%;
 
 ---MODEL (cam component) ----- cam timer ----- No. of calls - wall time (s)
 from CCSM3.0 cam's timing.0: ccsm_rcvtosnd --- 8761 ------ 69598.148
 from CCSM3.0 cam's timing.0: ccsm_sndtorcv --- 8760 ------ 28763.375
 --------------- CCSM3.0 cam total communication time w/ cpl: 98361.523
 
 --MODEL (cam component) ----- cam timer ----- No. of calls - wall time (s)
 from CCSM2.0.1 cam's!
 timing.0: ccsm_rcvtosnd --- 8761 ------ 46653.520
 from !
 CCSM2.0.
1 cam's timing.0: ccsm_sndtorcv --- 8760 ------ 12143.051
 -------------- CCSM2.0.1 cam total communication time w/ cpl: 58769.571
 
 2. The total time spent on all MPI routines (i.e. communication time)
 increased by about 33%. 
 MODEL ---- Total wall time spent on MPI calls
 CCSM3.0 : 18500 s
 CCSM2.0.1: 13894 s
 
 Most of the difference appears to be
 due to the replacement of "mpi_sendrecv" by "mpi_alltoallv":
 
 
 ---MODEL (cam component) ---- MPI function -- No. of calls -- wall time (s)
 from CCSM3.0 cam's timing.0: mpi_alltoallv -- 52562 ------- 16671.400
 from CCSM2.0.1 cam's timing.0: mpi_sendrecv --762120 ------- 4625.800
 
 3. Overall some of cam's most computationally intensive routines became significatnly slower:
 
 (Wall time in seconds)
 MODEL/ROUTINE phys_driver --- radctl --- dynpkg --- realloc4(a) 
 CCSM3.0 ----------------- 72292 ------ !
 35701 --- 38137 ----- 16870
 CSSM2.0.1 --------------- 54795 ------ 19286 --- 20077 ----- 1827
 
 ___________________
 
 Questions:
 
 A) Is there a simple way in to improve the performance of cam in CCSM3.0?
 
 B) Was there a significant increase in the calculations performed by cam's physics/dynamics algorithms,
 which might justify the 47% increase in wall time?
 Or is the MPI framework of the new "cam" in CCSM3.0 tuned to NCAR's shared memory machines,
 but not optimized to distributed memory beowulf clusters?
 
 ( I tried increasing cam's cpus from 6 to 8, while decreasing the land (clm) cpus from 4 to 2.
 However, CCSM3.0 (walltime 26h30min) is still 32% slower than CCSM2.0.1 (walltime 20h07min). 
 I guess the problem is beyond load balance, and CCSM3 is in fact slower than its predecessor. )
 
 C) Is there a simple option (namelist option, macro definition for compilation, or !
 other)
 that would restore the style of cam's MPI communi!
 cation t
o what it was in CCSM2.0.1,
 which seems to be more efficient on beowulf clusters?
 
 Thank you very much.
 
 Gus Correa

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

<<  What CAM simulations are available?, http://bb.cgd.ucar.edu//viewtopic.php?t=90 >>

PosterAdam PhillipsPostedFri Jan 14, 2005 11:21 pm MST, http://bb.cgd.ucar.edu//viewtopic.php?p=277#277
Message: Hi Dan,
 
 I ran two climatological SST runs using CAM3 on behalf of the Climate Variability Working Group. The T42 run is 200 years long, and the T85 run is 100 years long. They both are on our Mass Store:
 /ASPHILLI/csm/sstclimt42_run01/atm/hist
 /ASPHILLI/csm/sstclimt85_run01/atm/hist
 
 Various monthly, daily, and 4X daily fields were saved for both runs, as well as 2X daily multi-level fields for the T42 run. 
 
 Let me know if you have any questions about what variables where saved, or the runs in general.. I hope in the near future to create a web page that describes these runs, along with other runs that might be of interest to CVWG members in general...
 Adam

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