On 29 March, 6:37 a.m., "yongguang zhang" <[EMAIL PROTECTED]> wrote:
>I have download the GCM(HadleyCM3) projections data >from IPCC TAR and AR4. >The file format is netCDF or GRIB. >I really do not >know how to read these files. Basic documents and software of netCDF is available at the web page of Unidata Program Center http://www.unidata.ucar.edu/software/netcdf/ . GRIB is a format defined by WMO, so its authoritative document is somewhere in its web site (linked from the NCAR's page mentioned below). NCAR Data Support Section has a user's guide at http://dss.ucar.edu/docs/formats/ , and some software (source codes) is at http://dss.ucar.edu/libraries/grib/ . If the data you use are from CMIP3 (Coupled Model Intercomparison Project, phase 3), they are documented at PCMDI http://www-pcmdi.llnl.gov/ , and that web site also has some software tools (though I have not used them myself). >Plus, the units of precipitation projected by the GCM in AR4 >is kg/m^2 s^1, different from that in TAR, mm/day. >Anyone knows how to interpret the units >kg/m^2 s^1 to mm/day? As a physical quantity, precipiation rate should be defined as mass flux density, that is, mass of water running across a unit area (of ground surface) in a unit time. Its SI unit is kg/(m^2 s). We can approximate that the density of liquid water is constant and it has a round number 1 g/cm^3. Thus, 1 mm of height (i.e. volume per unit area) corresponds to 1 kg/m^2 of mass per unit area. The rest is conversion of units of time, which is how many seconds are there in a day, in this case. Ko-1 M. (Kooiti Masuda) --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/globalchange -~----------~----~----~----~------~----~------~--~---
