{"id":808,"date":"2020-02-07T17:32:56","date_gmt":"2020-02-07T21:32:56","guid":{"rendered":"https:\/\/www2.whoi.edu\/site\/aomip\/?page_id=808"},"modified":"2021-06-18T09:28:44","modified_gmt":"2021-06-18T13:28:44","slug":"background","status":"publish","type":"page","link":"https:\/\/www2.whoi.edu\/site\/aomip\/data\/atmospheric-forcing-data\/background\/","title":{"rendered":"Background"},"content":{"rendered":"\n\n\t<h1>Background<\/h1>\n<p>In response to urging from the climate modeling community, atmospheric research centers are now regularly producing consistent, global analysis of atmospheric fields spanning back in time over several decades. This technological feat is achieved by employing a frozen, state-of-the-art global data assimilation system and an atmospheric general circulation model to produce as consistent as possible a set of atmospheric fields. The resulting &#8220;reanalysis products&#8221; are highly suitable for use in a variety of climate modeling applications and in particular those directed towards understanding interannual and decadal climate variability, such as AOMIP.<\/p>\n<h2>NCEP\/NCAR Reanalysis<\/h2>\n<p>The National Centers for Environmental Protection (<a href=\"http:\/\/www.ncep.noaa.gov\/\">NCEP<\/a>) and the National Center for Atmospheric Research (<a href=\"https:\/\/www.ucar.edu\/\">NCAR<\/a>) carry out atmospheric\u00a0reanalysis projects.<\/p>\n<p>Their first notable product, NCEP\/NCAR-40, produced a 40 year record (1957-1996) of global analyses of atmospheric fields (<a href=\"https:\/\/www2.whoi.edu\/site\/aomip\/references\/\">Kalnay et al.<\/a>, 1996). Recently, that reanalysis product has been extended, NCEP\/NCAR-50, resulting in a record that now spans more than 50 years (1948-Present) (<a href=\"https:\/\/www2.whoi.edu\/site\/aomip\/references\/#Kistler_2001\">Kistler et al.<\/a>, 2001).<\/p>\n<p>The NCEP\/NCAR-50 reanalysis product is available in\u00a0<a href=\"https:\/\/www.esrl.noaa.gov\/psd\/arctic\/data\/\">NetCDF<\/a>\u00a0format from a\u00a0<a href=\"https:\/\/www.esrl.noaa.gov\/psd\/data\/gridded\/data.ncep.reanalysis.html\">data server<\/a>\u00a0at the Climate Diagnostics Center (<a href=\"http:\/\/www.cdc.noaa.gov\/index.html\">CDC<\/a>), an affiliate laboratory of the National Oceanographic and Atmospheric Administration (<a href=\"http:\/\/www.noaa.gov\/\">NOAA<\/a>). Modeling groups participating in the AOMIP 50-Year Experiment will use only the NetCDF data originating the AOMIP web site that has been copied from the CDC archive. This is to ensure that each AOMIP modeling group is using identical atmospheric forcing. The NCEP\/NCAR-50 data is available from other data centers and in other formats, (e.g., the more cumbersome GRIB format from a\u00a0data archive\u00a0at NCAR) but, again for consistency of intercomparison in AOMIP, only the NetCDF data set on the AOMIP website will be employed.<\/p>\n<h2>ECMWF Reanalysis<\/h2>\n<p>The European Center for Medium-Range Weather Forecasting (<a href=\"http:\/\/www.ecmwf.int\/\">ECMWF<\/a>) also carries out atmospheric\u00a0<a href=\"https:\/\/www.ecmwf.int\/en\/research\">reanalysis projects<\/a>.<\/p>\n<p>The first major project was\u00a0ERA-15\u00a0and covered a 15 year period (1979-1993). The reanalysis product from the ERA-15 project is available to UCAR affiliate institutions through a\u00a0data server\u00a0at the National Center for Atmospheric Research (NCAR).<\/p>\n<p>Currently a 40 year reanalysis project,\u00a0ERA-40, covering the period 1957-2001 is occurring. The completed reanalysis product will likely be available in Fall, 2002.<\/p>\n<p>The ECMWF reanalysis products will not be used in the AOMIP 50-Year experiment. As noted above, the AOMIP 50-Year Experiment will utilize the NCEP\/NCAR-50 reanalysis product to simulate the Arctic Ocean during the period 1948-Present. However, later stages of the AOMIP project may involve use of the ECMWF data.<\/p>\n<h2>OMIP Forcing<\/h2>\n<p>As a forcing data set for OMIP, the Max Plank Institute for Meteorology (MPI) has created an annual atmospheric climatology from the ERA-15 reanalysis product. The climatology has typical daily fluctuations imposed upon it using Gaussian filtering. There are 13 forcing fields in the OMIP Forcing data:<\/p>\n\n<table id=\"tablepress-25\" class=\"tablepress tablepress-id-25 tablepress-responsive\">\n<thead>\n<tr class=\"row-1 odd\">\n\t<th class=\"column-1\"><strong>Forcing Fields<\/strong><\/th>\n<\/tr>\n<\/thead>\n<tbody class=\"row-hover\">\n<tr class=\"row-2 even\">\n\t<td class=\"column-1\">Zonal Wind Stress (east\/west)<\/td>\n<\/tr>\n<tr class=\"row-3 odd\">\n\t<td class=\"column-1\">Meridional Wind Stress (north\/south)<\/td>\n<\/tr>\n<tr class=\"row-4 even\">\n\t<td class=\"column-1\">Scalar Wind<\/td>\n<\/tr>\n<tr class=\"row-5 odd\">\n\t<td class=\"column-1\">Daily Std. Dev. Scalar Wind<\/td>\n<\/tr>\n<tr class=\"row-6 even\">\n\t<td class=\"column-1\">Air Temperature (2 m)<\/td>\n<\/tr>\n<tr class=\"row-7 odd\">\n\t<td class=\"column-1\">Dewpoint Temperature (2 m)<\/td>\n<\/tr>\n<tr class=\"row-8 even\">\n\t<td class=\"column-1\">Sea-Surface Temperature<\/td>\n<\/tr>\n<tr class=\"row-9 odd\">\n\t<td class=\"column-1\">Total Shortwave Radiation<\/td>\n<\/tr>\n<tr class=\"row-10 even\">\n\t<td class=\"column-1\">Net Shortwave Radiation<\/td>\n<\/tr>\n<tr class=\"row-11 odd\">\n\t<td class=\"column-1\">Total Cloud Cover<\/td>\n<\/tr>\n<tr class=\"row-12 even\">\n\t<td class=\"column-1\">Precipitation<\/td>\n<\/tr>\n<tr class=\"row-13 odd\">\n\t<td class=\"column-1\">Evaporation<\/td>\n<\/tr>\n<tr class=\"row-14 even\">\n\t<td class=\"column-1\">River Runoff<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<!-- #tablepress-25 from cache -->\n<p>he data is available in this electronic format:<\/p>\n<ul>\n<li>ASCII \u00a0 (as separate ~ 0.1 GB files for each forcing field) from the\u00a0OMIP website<\/li>\n<\/ul>\n<p>Basic details about the ASCII data are found in descriptive text at the OMIP website, and are useful for understanding general aspects of the OMIP Forcing. There are currently no plans for use of the OMIP forcing in the AOMIP project. However, later stages of the AOMIP project may involve use of the OMIP data.<\/p>\n<h2>OMIP ASCII data descriptive text<\/h2>\nThe tar-files contain 12 files each: one file for one month.<br \/>\nEach of these files contains 30 days of data.<br \/>\nThe filenames are composed of the parameter name (see the list below)<br \/>\nand the month (01 for January, &#8230;, 12 for December).<br \/>\nThere are no missing values in the data.\nReading routine for one file containing data for one month:<br \/>\n===========================================================\nC<br \/>\nC\u00a0\u00a0\u00a0\u00a0 320 longitudes<br \/>\nC\u00a0\u00a0\u00a0\u00a0 160 latitudes<br \/>\nC\u00a0\u00a0\u00a0\u00a0 30 days per month<br \/>\nC<br \/>\nparameter(nxatm=320,nyatm=160,ndays=30)<br \/>\ndimension field(nxatm,nyatm),ifield(nxatm)\niunit=20<br \/>\nopen(iunit,file=filename,<br \/>\n2\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 form=&#8217;formatted&#8217;,access=&#8217;sequential&#8217;)\nC<br \/>\nC&#8212;&gt; signif is dependent on the format<br \/>\nC<br \/>\nsignif=10**4\u00a0\u00a0 [ or 10**5 or 10**6 ]\n999\u00a0\u00a0\u00a0 format(20I4)\u00a0\u00a0 [ or 16I5\u00a0 or 12I6,\u00a0 see list below]\ndo nd=1,ndays<br \/>\ndo j=1,nyatm<br \/>\nread(iunit,999) (ifield(i),i=1,nxatm)<br \/>\ndo i=1,nxatm<br \/>\nfield(i,j) = fac*float(ifield(i))\/signif + add<br \/>\nenddo<br \/>\nenddo<br \/>\nenddo\ndata<br \/>\n====\nparameter\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 add\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 fac\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 format\u00a0\u00a0 unit<br \/>\n&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n2m dewpoint temperature\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 190.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 120.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 20I4\u00a0\u00a0\u00a0\u00a0 K<br \/>\n2m temperature\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 190.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 130.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 20I4\u00a0\u00a0\u00a0\u00a0 K<br \/>\nzonal stress (east\/west)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 -4.3\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 8.6\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 12I6\u00a0\u00a0\u00a0\u00a0 Pa<br \/>\nevaporation\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 -2.8E-7\u00a0\u00a0\u00a0\u00a0\u00a0 3.2E-7\u00a0\u00a0\u00a0 16I5\u00a0\u00a0\u00a0\u00a0 m\/s<br \/>\nnet short wave solar radiation\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 410.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 16I5\u00a0\u00a0\u00a0\u00a0 W\/m^2<br \/>\nmeridional stress (north\/south)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 -3.3\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 6.0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 12I6\u00a0\u00a0\u00a0\u00a0 Pa<br \/>\nrunoff\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1.7E-5\u00a0\u00a0\u00a0 12I6\u00a0\u00a0\u00a0\u00a0 m\/s<br \/>\nscalar wind\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 27.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 16I5\u00a0\u00a0\u00a0\u00a0 m\/s<br \/>\nsea surface temperature\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 180.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 165.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 20I4\u00a0\u00a0\u00a0\u00a0 K<br \/>\ndaily std.dev. scalar wind\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (1)\u00a0\u00a0\u00a0 0.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 20.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 16I5\u00a0\u00a0\u00a0\u00a0 m\/s<br \/>\ntotal cloud cover\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1.1\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 20I4\u00a0\u00a0\u00a0\u00a0 (0-1)<br \/>\ntotal precipitation\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (2)\u00a0\u00a0 -4.1E-7\u00a0\u00a0\u00a0\u00a0\u00a0 2.8E-6\u00a0\u00a0\u00a0 12I6\u00a0\u00a0\u00a0\u00a0 m\/s<br \/>\ntotal short wave solar radiation\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 910.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 16I5\u00a0\u00a0\u00a0\u00a0 W\/m^2\n<p>land sea mask\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 0.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 80I1\u00a0\u00a0\u00a0\u00a0 1:sea\/0:land<\/p>\n(1) Daily standard deviation of scalar wind (two values per day).<br \/>\n(2) Negative precipitation due to inconsistencies in the use of GRIB.\nThe horizontal grid is described using the syntax of a GrADS control file:<br \/>\n==========================================================================<br \/>\n*<br \/>\n* Longitudes are specified by a linear relationship:<br \/>\n*<br \/>\n*\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 starting\u00a0\u00a0\u00a0 increment(=360\/320)<br \/>\n*\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 longitude<br \/>\n*\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 &#8212;&#8212;&#8212;\u00a0\u00a0 &#8212;&#8212;&#8212;&#8212;&#8212;&#8212;-<br \/>\nXDEF 320 LINEAR\u00a0\u00a0\u00a0\u00a0\u00a0 0.0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1.125000<br \/>\n*<br \/>\n*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;-<br \/>\n*<br \/>\n* All latitudes are specified starting at the South Pole:<br \/>\n*<br \/>\nYDEF 160 LEVELS<br \/>\n-89.1415 -88.0294 -86.9108 -85.7906 -84.6699 -83.5489 -82.4278 -81.3066<br \/>\n-80.1853 -79.0640 -77.9426 -76.8212 -75.6998 -74.5784 -73.4570 -72.3356<br \/>\n-71.2141 -70.0927 -68.9712 -67.8498 -66.7283 -65.6069 -64.4854 -63.3639<br \/>\n-62.2425 -61.1210 -59.9995 -58.8780 -57.7566 -56.6351 -55.5136 -54.3921<br \/>\n-53.2707 -52.1492 -51.0277 -49.9062 -48.7847 -47.6632 -46.5418 -45.4203<br \/>\n-44.2988 -43.1773 -42.0558 -40.9343 -39.8129 -38.6914 -37.5699 -36.4484<br \/>\n-35.3269 -34.2054 -33.0839 -31.9624 -30.8410 -29.7195 -28.5980 -27.4765<br \/>\n-26.3550 -25.2335 -24.1120 -22.9905 -21.8690 -20.7476 -19.6261 -18.5046<br \/>\n-17.3831 -16.2616 -15.1401 -14.0186 -12.8971 -11.7756 -10.6542\u00a0 -9.5327<br \/>\n-8.4112\u00a0 -7.2897\u00a0 -6.1682\u00a0 -5.0467\u00a0 -3.9252\u00a0 -2.8037\u00a0 -1.6822\u00a0 -0.5607<br \/>\n0.5607\u00a0\u00a0 1.6822\u00a0\u00a0 2.8037\u00a0\u00a0 3.9252\u00a0\u00a0 5.0467\u00a0\u00a0 6.1682\u00a0\u00a0 7.2897\u00a0\u00a0 8.4112<br \/>\n9.5327\u00a0 10.6542\u00a0 11.7756\u00a0 12.8971\u00a0 14.0186\u00a0 15.1401\u00a0 16.2616\u00a0 17.3831<br \/>\n18.5046\u00a0 19.6261\u00a0 20.7476\u00a0 21.8690\u00a0 22.9905\u00a0 24.1120\u00a0 25.2335\u00a0 26.3550<br \/>\n27.4765\u00a0 28.5980\u00a0 29.7195\u00a0 30.8410\u00a0 31.9624\u00a0 33.0839\u00a0 34.2054\u00a0 35.3269<br \/>\n36.4484\u00a0 37.5699\u00a0 38.6914\u00a0 39.8129\u00a0 40.9343\u00a0 42.0558\u00a0 43.1773\u00a0 44.2988<br \/>\n45.4203\u00a0 46.5418\u00a0 47.6632\u00a0 48.7847\u00a0 49.9062\u00a0 51.0277\u00a0 52.1492\u00a0 53.2707<br \/>\n54.3921\u00a0 55.5136\u00a0 56.6351\u00a0 57.7566\u00a0 58.8780\u00a0 59.9995\u00a0 61.1210\u00a0 62.2425<br \/>\n63.3639\u00a0 64.4854\u00a0 65.6069\u00a0 66.7283\u00a0 67.8498\u00a0 68.9712\u00a0 70.0927\u00a0 71.2141<br \/>\n72.3356\u00a0 73.4570\u00a0 74.5784\u00a0 75.6998\u00a0 76.8212\u00a0 77.9426\u00a0 79.0640\u00a0 80.1853<br \/>\n81.3066\u00a0 82.4278\u00a0 83.5489\u00a0 84.6699\u00a0 85.7906\u00a0 86.9108\u00a0 88.0294\u00a0 89.1415\n\n","protected":false},"excerpt":{"rendered":"<p>Background In response to urging from the climate modeling community, atmospheric research centers are now regularly producing consistent, global analysis of atmospheric fields spanning back in time over several decades. This technological feat is achieved by employing a frozen, state-of-the-art global data assimilation system and an atmospheric general circulation model to produce as consistent as&hellip;<\/p>\n","protected":false},"author":83,"featured_media":0,"parent":805,"menu_order":1,"comment_status":"closed","ping_status":"closed","template":"tpl-sidebar.php","meta":{"advanced-sidebar-menu\/link-title":"","advanced-sidebar-menu\/exclude-page":false},"_links":{"self":[{"href":"https:\/\/www2.whoi.edu\/site\/aomip\/wp-json\/wp\/v2\/pages\/808"}],"collection":[{"href":"https:\/\/www2.whoi.edu\/site\/aomip\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www2.whoi.edu\/site\/aomip\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/site\/aomip\/wp-json\/wp\/v2\/users\/83"}],"replies":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/site\/aomip\/wp-json\/wp\/v2\/comments?post=808"}],"version-history":[{"count":3,"href":"https:\/\/www2.whoi.edu\/site\/aomip\/wp-json\/wp\/v2\/pages\/808\/revisions"}],"predecessor-version":[{"id":1691,"href":"https:\/\/www2.whoi.edu\/site\/aomip\/wp-json\/wp\/v2\/pages\/808\/revisions\/1691"}],"up":[{"embeddable":true,"href":"https:\/\/www2.whoi.edu\/site\/aomip\/wp-json\/wp\/v2\/pages\/805"}],"wp:attachment":[{"href":"https:\/\/www2.whoi.edu\/site\/aomip\/wp-json\/wp\/v2\/media?parent=808"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}