Arctic Sea Ice : Forum
Cryosphere => Arctic sea ice => Topic started by: Michael on October 06, 2017, 10:20:03 AM
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These 0-10 day, experimental, sea ice forecasts are produced by the NOAA Physical Sciences Division from a fully coupled ice-ocean-atmosphere model called RASM-ESRL. RASM-ESRL is run daily and posted online at 2 UTC. The model is initialized with the NOAA Global Forecast System (GFS) analyses and the Advanced Microwave Scanning Radiometer 2 (AMSR2) sea ice concentrations. The model is forced at the lateral boundaries by 3-hourly GFS forecasts of winds, temperature, and water vapor.
Citation
Plot provided by the NOAA/ESRL Physical Sciences Division, Boulder, CO from their Web site at http://www.esrl.noaa.gov/psd/. (http://www.esrl.noaa.gov/psd/.)
url : https://www.esrl.noaa.gov/psd/forecasts/seaice/index.html (https://www.esrl.noaa.gov/psd/forecasts/seaice/index.html)
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The September minimum provides the idea opportunity to test the RASM_ESRL forecast in terms of sea ice extent, area and volume.
The REB.2017-09-dd.nc files provide a ten day forecast at 6 hourly steps. The first time step covers the time period 00:00 to 06:00, although it is not clear if this reflects the initial conditions or is a forecast for this period. It is this time period that is tracked from when it first appears at time step 36 until it finally appears as time step 0.
Below is tabulated the RASM_ESRL forecast for September Sea Ice Extent, for sea ice with a concentration greater than 15%.
The final column is the difference between the first forecast and the final value for that day.
| Date | _ | model time | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | __ | Time step |
| | | | 36 | | 32 | | 28 | | 24 | | 20 | | 16 | | 12 | | 8 | | 4 | | 0 | | 36 - 0 |
| 2017-09-01 | | 736448.25 | | 4.6 | | 4.5755 | | 4.5688 | | 4.6013 | | 4.6144 | | 4.6096 | | 4.6134 | | 4.4533 | | 4.4524 | | 4.4531 | | 0.1469 |
| 2017-09-02 | | 736449.25 | | 4.5741 | | 4.5763 | | 4.6182 | | 4.6149 | | 4.6004 | | 4.606 | | 4.4438 | | 4.4422 | | 4.4428 | | 4.4422 | | 0.1319 |
| 2017-09-03 | | 736450.25 | | 4.5789 | | 4.6262 | | 4.614 | | 4.5867 | | 4.5933 | | 4.4263 | | 4.4292 | | 4.4366 | | 4.4333 | | 4.4364 | | 0.1425 |
| 2017-09-04 | | 736451.25 | | 4.628 | | 4.6169 | | 4.5671 | | 4.5847 | | 4.4148 | | 4.4179 | | 4.4315 | | 4.4246 | | 4.4257 | | 4.4259 | | 0.2021 |
| 2017-09-05 | | 736452.25 | | 4.603 | | 4.5463 | | 4.5759 | | 4.3877 | | 4.4112 | | 4.422 | | 4.4181 | | 4.4255 | | 4.428 | | 4.4279 | | 0.1751 |
| 2017-09-06 | | 736453.25 | | 4.5368 | | 4.572 | | 4.3745 | | 4.4079 | | 4.4142 | | 4.4094 | | 4.4204 | | 4.4206 | | 4.4243 | | 4.3225 | | 0.2143 |
| 2017-09-07 | | 736454.25 | | 4.5809 | | 4.3663 | | 4.4037 | | 4.4077 | | 4.4002 | | 4.4199 | | 4.4168 | | 4.4183 | | 4.3393 | | 4.3391 | | 0.2418 |
| 2017-09-08 | | 736455.25 | | 4.3664 | | 4.4067 | | 4.3849 | | 4.4 | | 4.4193 | | 4.4042 | | 4.414 | | 4.3361 | | 4.341 | | 4.3416 | | 0.0248 |
| 2017-09-09 | | 736456.25 | | 4.42 | | 4.3641 | | 4.3963 | | 4.421 | | 4.4081 | | 4.4092 | | 4.3397 | | 4.3419 | | 4.3437 | | 4.3435 | | 0.0765 |
| 2017-09-10 | | 736457.25 | | 4.3515 | | 4.3971 | | 4.4292 | | 4.4224 | | 4.42 | | 4.3516 | | 4.3578 | | 4.353 | | 4.3534 | | 4.354 | | -0.0025 |
| 2017-09-11 | | 736458.25 | | 4.4088 | | 4.44 | | 4.44 | | 4.4298 | | 4.3611 | | 4.3635 | | 4.3646 | | 4.3685 | | 4.3678 | | 4.3673 | | 0.0415 |
| 2017-09-12 | | 736459.25 | | 4.4555 | | 4.4402 | | 4.4307 | | 4.3644 | | 4.3717 | | 4.3651 | | 4.3738 | | 4.3735 | | 4.3765 | | | | |
| 2017-09-13 | | 736460.25 | | 4.4492 | | 4.4359 | | 4.3652 | | 4.3712 | | 4.3581 | | 4.3724 | | 4.3735 | | 4.3756 | | | | 4.224 | | 0.2252 |
| 2017-09-14 | | 736461.25 | | 4.4473 | | 4.3697 | | 4.3716 | | 4.3657 | | 4.3778 | | 4.3851 | | 4.3817 | | | | 4.2398 | | 4.239 | | 0.2083 |
| 2017-09-15 | | 736462.25 | | 4.3841 | | 4.3627 | | 4.3769 | | 4.3817 | | 4.3938 | | 4.402 | | | | 4.2616 | | 4.2608 | | 4.2604 | | 0.1237 |
| 2017-09-16 | | 736463.25 | | 4.352 | | 4.3801 | | 4.3835 | | 4.4025 | | 4.4125 | | | | 4.2833 | | 4.2852 | | 4.277 | | 4.2263 | | 0.1257 |
| 2017-09-17 | | 736464.25 | | 4.3705 | | 4.3873 | | 4.4014 | | 4.4258 | | | | 4.2945 | | 4.297 | | 4.2977 | | 4.2546 | | 4.2548 | | 0.1157 |
| 2017-09-18 | | 736465.25 | | 4.4034 | | 4.4085 | | 4.4358 | | | | 4.3028 | | 4.309 | | 4.3207 | | 4.2734 | | 4.2815 | | 4.2811 | | 0.1223 |
| 2017-09-19 | | 736466.25 | | 4.4175 | | 4.4385 | | | | 4.3327 | | 4.3189 | | 4.337 | | 4.2907 | | 4.3019 | | 4.3069 | | 4.3821 | | 0.0354 |
| 2017-09-20 | | 736467.25 | | 4.4398 | | | | 4.3494 | | 4.3523 | | 4.3733 | | 4.3506 | | 4.3828 | | 4.3873 | | 4.4454 | | 4.526 | | -0.0862 |
| 2017-09-21 | | 736468.25 | | | | 4.3539 | | 4.3968 | | 4.4337 | | 4.4231 | | 4.4425 | | 4.4435 | | 4.4961 | | 4.5529 | | 4.554 | | |
| 2017-09-22 | | 736469.25 | | 4.3628 | | 4.4207 | | 4.4773 | | 4.4598 | | 4.4675 | | 4.4679 | | 4.524 | | 4.5766 | | 4.5779 | | 4.5783 | | -0.2155 |
| 2017-09-23 | | 736470.25 | | 4.438 | | 4.4897 | | 4.4688 | | 4.4747 | | 4.4819 | | 4.5391 | | 4.5855 | | 4.5922 | | 4.5911 | | 4.592 | | -0.154 |
| 2017-09-24 | | 736471.25 | | 4.501 | | 4.4669 | | 4.4746 | | 4.4978 | | 4.5571 | | 4.5957 | | 4.6087 | | 4.6055 | | 4.6117 | | 4.6121 | | -0.1111 |
| 2017-09-25 | | 736472.25 | | 4.4729 | | 4.4815 | | 4.5136 | | 4.5794 | | 4.6294 | | 4.6335 | | 4.6394 | | 4.6513 | | 4.6577 | | 4.6558 | | -0.1829 |
| 2017-09-26 | | 736473.25 | | 4.4968 | | 4.5385 | | 4.6263 | | 4.6734 | | 4.6822 | | 4.6963 | | 4.7021 | | 4.7104 | | 4.7109 | | 4.711 | | -0.2142 |
| 2017-09-27 | | 736474.25 | | 4.5671 | | 4.6743 | | 4.7119 | | 4.7203 | | 4.7408 | | 4.7524 | | 4.7644 | | 4.7647 | | 4.7614 | | 4.7221 | | -0.155 |
| 2017-09-28 | | 736475.25 | | 4.7013 | | 4.7532 | | 4.7581 | | 4.7927 | | 4.8219 | | 4.831 | | 4.819 | | 4.8184 | | 4.8304 | | 4.8312 | | -0.1299 |
| 2017-09-29 | | 736476.25 | | 4.789 | | 4.7962 | | 4.8236 | | 4.8761 | | 4.884 | | 4.8589 | | 4.8602 | | 4.8687 | | 4.8746 | | 4.8747 | | -0.0857 |
| 2017-09-30 | | 736477.25 | | 4.8491 | | 4.8616 | | 4.9178 | | 4.9364 | | 4.8856 | | 4.8976 | | 4.9033 | | 4.9076 | | 4.906 | | 4.9042 | | -0.0551 |
For convenience I am splitting this post into three. Sea Ice Area follows...
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...Below is tabulated the RASM_ESRL forecast for September Sea Ice Area, for sea ice with a concentration greater than 15%.
The final column is the difference between the first forecast and the final value for that day.
| Date | _ | model time | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | __ | Time step |
| | | | 36 | | 32 | | 28 | | 24 | | 20 | | 16 | | 12 | | 8 | | 4 | | 0 | | 36 - 0 |
| 2017-09-01 | | 736448.25 | | 3.7724 | | 3.7491 | | 3.7539 | | 3.7622 | | 3.7755 | | 3.7742 | | 3.7782 | | 3.653 | | 3.6552 | | 3.6556 | | 0.1168 |
| 2017-09-02 | | 736449.25 | | 3.7395 | | 3.7458 | | 3.7541 | | 3.7674 | | 3.7658 | | 3.7705 | | 3.6417 | | 3.6447 | | 3.6462 | | 3.6464 | | 0.0931 |
| 2017-09-03 | | 736450.25 | | 3.7402 | | 3.7472 | | 3.7604 | | 3.7592 | | 3.7639 | | 3.6317 | | 3.6352 | | 3.6375 | | 3.6386 | | 3.6378 | | 0.1024 |
| 2017-09-04 | | 736451.25 | | 3.7412 | | 3.7544 | | 3.753 | | 3.7559 | | 3.6225 | | 3.6234 | | 3.6273 | | 3.6279 | | 3.6286 | | 3.6291 | | 0.1121 |
| 2017-09-05 | | 736452.25 | | 3.7446 | | 3.7442 | | 3.7434 | | 3.6063 | | 3.614 | | 3.6194 | | 3.619 | | 3.6212 | | 3.6238 | | 3.6239 | | 0.1207 |
| 2017-09-06 | | 736453.25 | | 3.7358 | | 3.7299 | | 3.5899 | | 3.6059 | | 3.6147 | | 3.6135 | | 3.616 | | 3.619 | | 3.6213 | | 3.7573 | | -0.0215 |
| 2017-09-07 | | 736454.25 | | 3.7219 | | 3.579 | | 3.5963 | | 3.6099 | | 3.6097 | | 3.6107 | | 3.6149 | | 3.6186 | | 3.7388 | | 3.7394 | | -0.0175 |
| 2017-09-08 | | 736455.25 | | 3.5693 | | 3.5867 | | 3.6012 | | 3.6073 | | 3.6051 | | 3.6095 | | 3.6162 | | 3.7309 | | 3.7357 | | 3.7362 | | -0.1669 |
| 2017-09-09 | | 736456.25 | | 3.5797 | | 3.5929 | | 3.6038 | | 3.602 | | 3.6093 | | 3.6151 | | 3.728 | | 3.7343 | | 3.7383 | | 3.7386 | | -0.1589 |
| 2017-09-10 | | 736457.25 | | 3.5875 | | 3.6013 | | 3.5997 | | 3.6102 | | 3.615 | | 3.7243 | | 3.7312 | | 3.7367 | | 3.7399 | | 3.7404 | | -0.1529 |
| 2017-09-11 | | 736458.25 | | 3.603 | | 3.5972 | | 3.6134 | | 3.6147 | | 3.7207 | | 3.727 | | 3.7324 | | 3.7353 | | 3.7377 | | 3.738 | | -0.135 |
| 2017-09-12 | | 736459.25 | | 3.5971 | | 3.6226 | | 3.6182 | | 3.7172 | | 3.7263 | | 3.726 | | 3.7296 | | 3.7337 | | 3.7374 | | | | |
| 2017-09-13 | | 736460.25 | | 3.639 | | 3.6248 | | 3.7162 | | 3.726 | | 3.7277 | | 3.7305 | | 3.7356 | | 3.7388 | | | | 3.7638 | | -0.1248 |
| 2017-09-14 | | 736461.25 | | 3.6359 | | 3.7175 | | 3.7265 | | 3.7375 | | 3.7325 | | 3.7327 | | 3.7462 | | | | 3.7502 | | 3.751 | | -0.1151 |
| 2017-09-15 | | 736462.25 | | 3.7202 | | 3.7226 | | 3.7467 | | 3.7327 | | 3.7362 | | 3.7579 | | | | 3.7459 | | 3.7545 | | 3.7546 | | -0.0344 |
| 2017-09-16 | | 736463.25 | | 3.7195 | | 3.7472 | | 3.7375 | | 3.743 | | 3.77 | | | | 3.7546 | | 3.7656 | | 3.7634 | | 3.596 | | 0.1235 |
| 2017-09-17 | | 736464.25 | | 3.7377 | | 3.7494 | | 3.744 | | 3.7706 | | | | 3.7721 | | 3.7785 | | 3.7794 | | 3.6371 | | 3.6372 | | 0.1005 |
| 2017-09-18 | | 736465.25 | | 3.7618 | | 3.7494 | | 3.7749 | | | | 3.7842 | | 3.795 | | 3.8072 | | 3.6893 | | 3.6999 | | 3.7002 | | 0.0616 |
| 2017-09-19 | | 736466.25 | | 3.7582 | | 3.7891 | | | | 3.8014 | | 3.8132 | | 3.8217 | | 3.7273 | | 3.7406 | | 3.7501 | | 3.7975 | | -0.0393 |
| 2017-09-20 | | 736467.25 | | 3.8008 | | | | 3.8216 | | 3.8552 | | 3.8338 | | 3.7667 | | 3.7865 | | 3.7989 | | 3.8697 | | 4.0958 | | -0.295 |
| 2017-09-21 | | 736468.25 | | | | 3.8312 | | 3.9097 | | 3.869 | | 3.8208 | | 3.8399 | | 3.8571 | | 3.9176 | | 4.1293 | | 4.1302 | | |
| 2017-09-22 | | 736469.25 | | 3.8305 | | 3.9316 | | 3.9096 | | 3.8527 | | 3.8644 | | 3.884 | | 3.941 | | 4.1368 | | 4.1432 | | 4.144 | | -0.3135 |
| 2017-09-23 | | 736470.25 | | 3.9472 | | 3.9269 | | 3.863 | | 3.8708 | | 3.8943 | | 3.9477 | | 4.1308 | | 4.1397 | | 4.1475 | | 4.1487 | | -0.2015 |
| 2017-09-24 | | 736471.25 | | 3.9392 | | 3.8667 | | 3.8718 | | 3.9051 | | 3.9589 | | 4.1248 | | 4.1395 | | 4.1545 | | 4.1627 | | 4.1637 | | -0.2245 |
| 2017-09-25 | | 736472.25 | | 3.8733 | | 3.8809 | | 3.9227 | | 3.9826 | | 4.1308 | | 4.1508 | | 4.174 | | 4.1829 | | 4.2004 | | 4.2007 | | -0.3274 |
| 2017-09-26 | | 736473.25 | | 3.9072 | | 3.9475 | | 4.0167 | | 4.1543 | | 4.1694 | | 4.2081 | | 4.2198 | | 4.2438 | | 4.2556 | | 4.2554 | | -0.3482 |
| 2017-09-27 | | 736474.25 | | 3.9933 | | 4.0646 | | 4.1808 | | 4.1947 | | 4.2401 | | 4.2639 | | 4.2985 | | 4.3067 | | 4.3162 | | 4.3572 | | -0.3639 |
| 2017-09-28 | | 736475.25 | | 4.1137 | | 4.2161 | | 4.2371 | | 4.2963 | | 4.3364 | | 4.3674 | | 4.3727 | | 4.3824 | | 4.4174 | | 4.4172 | | -0.3035 |
| 2017-09-29 | | 736476.25 | | 4.2621 | | 4.2875 | | 4.3485 | | 4.4163 | | 4.4356 | | 4.4247 | | 4.444 | | 4.464 | | 4.4882 | | 4.4884 | | -0.2263 |
| 2017-09-30 | | 736477.25 | | 4.3395 | | 4.3922 | | 4.4611 | | 4.5162 | | 4.4669 | | 4.4929 | | 4.5002 | | 4.5255 | | 4.5295 | | 4.5294 | | -0.1899 |
Sea Ice Volume follows...
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...Below is tabulated the RASM_ESRL forecast for September Sea Ice Volume.
The final column is the difference between the first forecast and the final value for that day.
| Date | _ | model time | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | _ | Time step | __ | Time step |
| | | | 36 | | 32 | | 28 | | 24 | | 20 | | 16 | | 12 | | 8 | | 4 | | 0 | | 36 - 0 |
| 20170901 | | 736448.25 | | 7.2921 | | 7.2719 | | 7.2809 | | 7.2653 | | 7.2506 | | 7.2517 | | 7.2588 | | 6.9928 | | 6.9672 | | 6.95 | | 0.3421 |
| 20170902 | | 736449.25 | | 7.2629 | | 7.2645 | | 7.242 | | 7.2321 | | 7.2366 | | 7.2479 | | 6.9849 | | 6.964 | | 6.9544 | | 6.9458 | | 0.3171 |
| 20170903 | | 736450.25 | | 7.2487 | | 7.2228 | | 7.2197 | | 7.2322 | | 7.2414 | | 6.9784 | | 6.9597 | | 6.9512 | | 6.9493 | | 6.938 | | 0.3107 |
| 20170904 | | 736451.25 | | 7.2086 | | 7.2036 | | 7.2346 | | 7.2341 | | 6.9719 | | 6.949 | | 6.9457 | | 6.9461 | | 6.9426 | | 6.9381 | | 0.2705 |
| 20170905 | | 736452.25 | | 7.1855 | | 7.2346 | | 7.2171 | | 6.9627 | | 6.9366 | | 6.9468 | | 6.9454 | | 6.9439 | | 6.9482 | | 6.9283 | | 0.2572 |
| 20170906 | | 736453.25 | | 7.2328 | | 7.1945 | | 6.9443 | | 6.9267 | | 6.9426 | | 6.9454 | | 6.9435 | | 6.9543 | | 6.9391 | | 7.1092 | | 0.1236 |
| 20170907 | | 736454.25 | | 7.1709 | | 6.9378 | | 6.9163 | | 6.9358 | | 6.9379 | | 6.9312 | | 6.9506 | | 6.9401 | | 7.1099 | | 7.0986 | | 0.0723 |
| 20170908 | | 736455.25 | | 6.9331 | | 6.9004 | | 6.9268 | | 6.9279 | | 6.9158 | | 6.9403 | | 6.9335 | | 7.106 | | 7.1093 | | 7.1096 | | -0.1765 |
| 20170909 | | 736456.25 | | 6.8821 | | 6.9178 | | 6.9184 | | 6.8959 | | 6.9266 | | 6.9243 | | 7.0994 | | 7.1085 | | 7.1229 | | 7.1165 | | -0.2344 |
| 20170910 | | 736457.25 | | 6.9122 | | 6.9 | | 6.8656 | | 6.9094 | | 6.9042 | | 7.0755 | | 7.0869 | | 7.1057 | | 7.1074 | | 7.0965 | | -0.1843 |
| 20170911 | | 736458.25 | | 6.9017 | | 6.8462 | | 6.9036 | | 6.8863 | | 7.0514 | | 7.0649 | | 7.0832 | | 7.0837 | | 7.0837 | | 7.0703 | | -0.1686 |
| 20170912 | | 736459.25 | | 6.8306 | | 6.9113 | | 6.8817 | | 7.0292 | | 7.0528 | | 7.0651 | | 7.0676 | | 7.0722 | | 7.0689 | | | | |
| 20170913 | | 736460.25 | | 6.9263 | | 6.89 | | 7.0177 | | 7.0502 | | 7.0707 | | 7.0706 | | 7.0732 | | 7.0717 | | | | 7.0347 | | -0.1084 |
| 20170914 | | 736461.25 | | 6.9066 | | 7.0054 | | 7.0488 | | 7.0786 | | 7.0605 | | 7.0516 | | 7.0781 | | | | 7.0365 | | 7.0241 | | -0.1175 |
| 20170915 | | 736462.25 | | 7.0011 | | 7.0418 | | 7.0787 | | 7.0512 | | 7.0444 | | 7.0799 | | | | 7.0233 | | 7.0321 | | 7.0285 | | -0.0274 |
| 20170916 | | 736463.25 | | 7.032 | | 7.0677 | | 7.0571 | | 7.0383 | | 7.0841 | | | | 7.0298 | | 7.0474 | | 7.0475 | | 5.9651 | | 1.0669 |
| 20170917 | | 736464.25 | | 7.0497 | | 7.0682 | | 7.0366 | | 7.074 | | | | 7.0458 | | 7.0611 | | 7.0668 | | 5.9917 | | 5.991 | | 1.0587 |
| 20170918 | | 736465.25 | | 7.0667 | | 7.0487 | | 7.079 | | | | 7.0507 | | 7.0769 | | 7.0959 | | 6.0365 | | 6.0541 | | 6.0564 | | 1.0103 |
| 20170919 | | 736466.25 | | 7.0606 | | 7.1023 | | | | 7.075 | | 7.1091 | | 7.1004 | | 6.0647 | | 6.0868 | | 6.1044 | | 6.1175 | | 0.9431 |
| 20170920 | | 736467.25 | | 7.1316 | | | | 7.1055 | | 7.1895 | | 7.0937 | | 6.0712 | | 6.0837 | | 6.1052 | | 6.1394 | | 6.2905 | | 0.8411 |
| 20170921 | | 736468.25 | | | | 7.1166 | | 7.245 | | 7.1212 | | 6.0667 | | 6.0712 | | 6.0962 | | 6.1243 | | 6.2588 | | 6.269 | | | | |
| 20170922 | | 736469.25 | | 7.0983 | | 7.2508 | | 7.1479 | | 6.0537 | | 6.0604 | | 6.0821 | | 6.1046 | | 6.22 | | 6.24 | | 6.2449 | | 0.8534 |
| 20170923 | | 736470.25 | | 7.2541 | | 7.1497 | | 6.0501 | | 6.054 | | 6.0643 | | 6.081 | | 6.1927 | | 6.218 | | 6.2316 | | 6.2364 | | 1.0177 |
| 20170924 | | 736471.25 | | 7.1574 | | 6.0518 | | 6.052 | | 6.0549 | | 6.0636 | | 6.1664 | | 6.1955 | | 6.2201 | | 6.2316 | | 6.2385 | | 0.9189 |
| 20170925 | | 736472.25 | | 6.0524 | | 6.0564 | | 6.0596 | | 6.0667 | | 6.146 | | 6.1832 | | 6.2138 | | 6.2236 | | 6.2437 | | 6.2511 | | -0.1987 |
| 20170926 | | 736473.25 | | 6.0761 | | 6.0658 | | 6.0836 | | 6.1418 | | 6.1742 | | 6.2074 | | 6.2204 | | 6.2469 | | 6.2729 | | 6.2807 | | -0.2046 |
| 20170927 | | 736474.25 | | 6.0971 | | 6.1149 | | 6.1376 | | 6.1675 | | 6.1944 | | 6.2149 | | 6.2462 | | 6.2745 | | 6.2973 | | 6.4698 | | -0.3727 |
| 20170928 | | 736475.25 | | 6.1609 | | 6.1453 | | 6.1819 | | 6.208 | | 6.2283 | | 6.2585 | | 6.2896 | | 6.3083 | | 6.4697 | | 6.4812 | | -0.3203 |
| 20170929 | | 736476.25 | | 6.1598 | | 6.1928 | | 6.2333 | | 6.2624 | | 6.2816 | | 6.31 | | 6.3352 | | 6.4699 | | 6.4985 | | 6.5145 | | -0.3547 |
| 20170930 | | 736477.25 | | 6.2068 | | 6.2604 | | 6.2787 | | 6.3148 | | 6.3202 | | 6.3539 | | 6.4668 | | 6.497 | | 6.5156 | | 6.5297 | | -0.3229 |
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The RASM_ESRL model uses a 10 km polar stereoscopic grid with a Standard Latitude of 84.5N, on a spherical Earth with a radius of 6370 km.
The RASM_ESRL grid is reported as an Arakawa B-grid (scalars at centre, vectors at NE corner), but what relationship this has with the POP/CICE Arakawa B-grid is unclear. Certainly they are not coincident, the RASM_ESRL grid varies in grid cell size from 9.364 to 10.023 km while the maximum size of the POP/CICE grid is 9.264 km. Also the 1/12 degree mesh used by POP/CICE appears to have an "equator" around the 157/337 degree meridian. As the RASM_ESRL model is a synthesis of several models, each with different properties, it would seem more sensible to use an Arakawa A-grid with scalars and vectors at the centre of the grid cells for the RASM_ESRL model.
The choice of a spherical earth grid is also curious. If the model is to have a real world use it would seem more logical to use a grid based on the WGS84 ellipsoid.
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Below is a summary of RASM_ESRL Sea Ice for September 2017.
As there is no official "nowcast" the first time step in the REB.2017-09-dd.nc files is assumed to be representative of that day.
Extent and Area are calculated for sea ice with a concentration greater than 15%.
The Effective Thickness in the final column is the average effective thickness for sea ice thicker than 0.15 m. This figure is directly comparable with the PIOMAS Average Thickness chart.
There is no data file for 12 September 2017.
Units : Extent and Area - 106 km2, Volume - 103 km3, Thickness - m
| Date | _ | model time | _ | Extent | _ | Area | _ | Volume | _ | Average | __ | *Effective |
| | | | | | | | | | thickness | | thickness* |
| 2017-09-01 | | 736448.25 | | 4.4531 | | 3.6556 | | 6.95 | | 1.8896 | | 1.5048 |
| 2017-09-02 | | 736449.25 | | 4.4422 | | 3.6464 | | 6.9458 | | 1.8933 | | 1.5047 |
| 2017-09-03 | | 736450.25 | | 4.4364 | | 3.6378 | | 6.938 | | 1.8957 | | 1.5032 |
| 2017-09-04 | | 736451.25 | | 4.4259 | | 3.6291 | | 6.9381 | | 1.8999 | | 1.5038 |
| 2017-09-05 | | 736452.25 | | 4.4279 | | 3.6239 | | 6.9283 | | 1.8999 | | 1.4998 |
| 2017-09-06 | | 736453.25 | | 4.3225 | | 3.7573 | | 7.1092 | | 1.8835 | | 1.6298 |
| 2017-09-07 | | 736454.25 | | 4.3391 | | 3.7394 | | 7.0986 | | 1.8895 | | 1.6143 |
| 2017-09-08 | | 736455.25 | | 4.3416 | | 3.7362 | | 7.1096 | | 1.8942 | | 1.614 |
| 2017-09-09 | | 736456.25 | | 4.3435 | | 3.7386 | | 7.1165 | | 1.8946 | | 1.6123 |
| 2017-09-10 | | 736457.25 | | 4.354 | | 3.7404 | | 7.0965 | | 1.8884 | | 1.6016 |
| 2017-09-11 | | 736458.25 | | 4.3673 | | 3.738 | | 7.0703 | | 1.8827 | | 1.5888 |
| 2017-09-12 | | 736459.25 | | | | | | | | | |
| 2017-09-13 | | 736460.25 | | 4.224 | | 3.7638 | | 7.0347 | | 1.861 | | 1.6587 |
| 2017-09-14 | | 736461.25 | | 4.239 | | 3.751 | | 7.0241 | | 1.8639 | | 1.6394 |
| 2017-09-15 | | 736462.25 | | 4.2604 | | 3.7546 | | 7.0285 | | 1.8638 | | 1.6336 |
| 2017-09-16 | | 736463.25 | | 4.2263 | | 3.596 | | 5.9651 | | 1.651 | | 1.4457 |
| 2017-09-17 | | 736464.25 | | 4.2548 | | 3.6372 | | 5.991 | | 1.6397 | | 1.4464 |
| 2017-09-18 | | 736465.25 | | 4.2811 | | 3.7002 | | 6.0564 | | 1.6295 | | 1.4581 |
| 2017-09-19 | | 736466.25 | | 4.3821 | | 3.7975 | | 6.1175 | | 1.6047 | | 1.4571 |
| 2017-09-20 | | 736467.25 | | 4.526 | | 4.0958 | | 6.2905 | | 1.5298 | | 1.5211 |
| 2017-09-21 | | 736468.25 | | 4.554 | | 4.1302 | | 6.269 | | 1.5121 | | 1.5033 |
| 2017-09-22 | | 736469.25 | | 4.5783 | | 4.144 | | 6.2449 | | 1.5014 | | 1.4869 |
| 2017-09-23 | | 736470.25 | | 4.592 | | 4.1487 | | 6.2364 | | 1.4976 | | 1.4781 |
| 2017-09-24 | | 736471.25 | | 4.6121 | | 4.1637 | | 6.2385 | | 1.4924 | | 1.4701 |
| 2017-09-25 | | 736472.25 | | 4.6558 | | 4.2007 | | 6.2511 | | 1.4826 | | 1.463 |
| 2017-09-26 | | 736473.25 | | 4.711 | | 4.2554 | | 6.2807 | | 1.471 | | 1.4606 |
| 2017-09-27 | | 736474.25 | | 4.7221 | | 4.3572 | | 6.4698 | | 1.4799 | | 1.4956 |
| 2017-09-28 | | 736475.25 | | 4.8312 | | 4.4172 | | 6.4812 | | 1.4618 | | 1.4857 |
| 2017-09-29 | | 736476.25 | | 4.8747 | | 4.4884 | | 6.5145 | | 1.4459 | | 1.4828 |
| 2017-09-30 | | 736477.25 | | 4.9042 | | 4.5294 | | 6.5297 | | 1.4364 | | 1.4779 |
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no official "nowcast" the first time step in the REB.2017-09-dd.nc files is assumed ...seem more sensible to use an Arakawa A-grid with scalars and vectors at the centre of the grid cells for the RASM_ESRL model.... seem more logical to use a grid based on the WGS84 ellipsoid.... hat relationship this has with the POP/CICE Arakawa B-grid
So what did they say when you wrote them with these questions/suggestions?
They solicit feedback, emails are shown. There are other issues, like going on with the 'Alaska-centric' view on some of their daily offerings, rather than whole Arctic Ocean plus Barents view that they announced back in mid-August. Some of the static graphic pairs are mis-sized. Contouring is over-writing binned visualizations, unnecessary. No data files provided for some graphics, not easy to duplicate.
Panoply updated this morning to 4.8.4 (windows, mac, linux) for those wishing to make maps from REB.2017-09-05 or RASM-ESRL_2017-10-05.
https://www.giss.nasa.gov/tools/panoply/ (https://www.giss.nasa.gov/tools/panoply/)
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So what did they say when you wrote them with these questions/suggestions?
They were very helpful, but reticent.
Helpful in providing the details of their grid so that I could generate the figures for extent etc.
They are very reticent when it comes to the CICE model. The team running RASM is based at the Naval Postgraduate School, and their website is an official Navy website. So there are possible security issues involved. The RASM team are currently working on implementing a 1/48 degree mesh for CICE, which will give it a finer resolution than the 3.125 km that HYCOM-CICE achieves with a tripole grid.
The RASM-ESRL team appear to be open to suggestions, but as the project seems to be under development there will probably be changes as things settle down.
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Sea ice concentration is fundamental to the operation of the CICE element of the RASM-RSRL model, and as it is initialized with ASMR2 a comparison with Uni Hamburg sea ice concentration seems justified.
RASM-ESRL data for the period 00:00 to 06:00 7 Oct 2017 is used for the comparison. The Uni Hamburg 3.125 km data have been regridded onto the RASM-ESRL 10 km grid.
I have used the HYCOM CICE colour scales and have included daily RASM-ESRL sea ice concentration and thickness.
* Click to animate GIF*
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@ Neven : I had the same problem previously reported with .PNG images with the above animated .GIF.
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We're looking into it (https://forum.arctic-sea-ice.net/index.php/topic,254.msg132573.html#msg132573), Michael. I'll report there that you experience the same problem with an animated GIF.
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This problem with images should be fixed now (probably until next version, I'll reapply it when necessary). Sorry for the delay.
And thanks for your posts!
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Rather belatedly, here is a summary of RASM_ESRL Sea Ice for October 2017.
I have used the REB.2017-10-dd.nc files, and taken time step 0 as being the "nowcast" and time step 39 as being the day 10 forecast.
Extent and Area are calculated for sea ice with a concentration greater than 15%.
The Effective Thickness in the final column is the average effective thickness for sea ice thicker than 0.15 m. This figure is directly comparable with the PIOMAS Average Thickness chart.
Units : Extent and Area - 10^6 km^2, Volume - 10^3 km3, Thickness - m
| Date | _ | model time | _ | Extent | _ | Area | _ | Volume | _ | Average | __ | Maximum | __ | *Effective |
| | | | | | | | | | thickness | | thickness | | thickness* |
| 20171001 | | 736478.25 | | 4.9413 | | 4.5659 | | 6.5435 | | 1.428 | | 3.6076 | | 1.4714 |
| 20171002 | | 736479.25 | | 4.9737 | | 4.6028 | | 6.5618 | | 1.4206 | | 3.5998 | | 1.4666 |
| 20171003 | | 736480.25 | | 5.0048 | | 4.635 | | 6.5703 | | 1.4126 | | 3.5944 | | 1.4591 |
| 20171004 | | 736481.25 | | 5.1015 | | 4.7681 | | 6.7145 | | 1.4041 | | 3.6102 | | 1.4567 |
| 20171005 | | 736482.25 | | 5.1815 | | 4.8086 | | 6.7243 | | 1.3934 | | 3.6073 | | 1.4506 |
| 20171006 | | 736483.25 | | 5.2753 | | 4.8832 | | 6.744 | | 1.3753 | | 3.605 | | 1.4442 |
| 20171007 | | 736484.25 | | 5.3912 | | 4.9675 | | 6.7579 | | 1.3553 | | 3.6033 | | 1.431 |
| 20171008 | | 736485.25 | | 5.4651 | | 5.0476 | | 6.7767 | | 1.3382 | | 3.6017 | | 1.4193 |
| 20171009 | | 736486.25 | | 5.5182 | | 5.1169 | | 6.7988 | | 1.3245 | | 3.5981 | | 1.4077 |
| 20171010 | | 736487.25 | | 5.5751 | | 5.1802 | | 6.8322 | | 1.3148 | | 3.5932 | | 1.3962 |
| 20171011 | | 736488.25 | | 5.6437 | | 5.2382 | | 6.5741 | | 1.2505 | | 3.5895 | | 1.3446 |
| 20171012 | | 736489.25 | | 5.8243 | | 5.3877 | | 6.6087 | | 1.2222 | | 3.584 | | 1.3362 |
| 20171013 | | 736490.25 | | 5.9332 | | 5.4971 | | 6.6438 | | 1.2048 | | 3.5756 | | 1.3263 |
| 20171014 | | 736491.25 | | 6.0014 | | 5.5797 | | 6.6784 | | 1.1933 | | 3.571 | | 1.3077 |
| 20171015 | | 736492.25 | | 6.0732 | | 5.6625 | | 6.7134 | | 1.182 | | 3.5685 | | 1.289 |
| 20171016 | | 736493.25 | | 6.1664 | | 5.7515 | | 6.7429 | | 1.1689 | | 3.5661 | | 1.2683 |
| 20171017 | | 736494.25 | | 6.2969 | | 5.858 | | 6.775 | | 1.1534 | | 3.5635 | | 1.2484 |
| 20171018 | | 736495.25 | | 6.2728 | | 5.8816 | | 6.8526 | | 1.1602 | | 3.5626 | | 1.2564 |
| 20171019 | | 736496.25 | | 6.6861 | | 6.1925 | | 6.9144 | | 1.1142 | | 3.5605 | | 1.2369 |
| 20171020 | | 736497.25 | | 6.7947 | | 6.428 | | 6.99 | | 1.0852 | | 3.5594 | | 1.2229 |
| 20171021 | | 736498.25 | | 6.8867 | | 6.5625 | | 7.0504 | | 1.0723 | | 3.5581 | | 1.2114 |
| 20171022 | | 736499.25 | | 6.9822 | | 6.5764 | | 7.0826 | | 1.0749 | | 3.5545 | | 1.1706 |
| 20171023 | | 736500.25 | | 7.0649 | | 6.6531 | | 7.1374 | | 1.0708 | | 3.5522 | | 1.1454 |
| 20171024 | | 736501.25 | | 7.1329 | | 6.7285 | | 7.1988 | | 1.0679 | | 3.5507 | | 1.1286 |
| 20171025 | | 736502.25 | | 7.0576 | | 6.6649 | | 7.2726 | | 1.0885 | | 3.5503 | | 1.1394 |
| 20171026 | | 736503.25 | | 7.3263 | | 6.8983 | | 7.3667 | | 1.0662 | | 3.5465 | | 1.1312 |
| 20171027 | | 736504.25 | | 7.4048 | | 7.0494 | | 7.4528 | | 1.0556 | | 3.5441 | | 1.1197 |
| 20171028 | | 736505.25 | | 7.4716 | | 7.116 | | 7.5245 | | 1.0557 | | 3.5438 | | 1.1094 |
| 20171029 | | 736506.25 | | 7.5305 | | 7.1638 | | 7.5925 | | 1.058 | | 3.5435 | | 1.1007 |
| 20171030 | | 736507.25 | | 7.5658 | | 7.1935 | | 7.6361 | | 1.0597 | | 3.5383 | | 1.0964 |
| 20171031 | | 736508.25 | | 7.6067 | | 7.2332 | | 7.7033 | | 1.0632 | | 3.5381 | | 1.0957 |
It is notable that thickness decreases during the month. This is possibly because the RASM-ESRL model is not manufacturing enough sea ice to keep pace with the increase in extent.
Below are animations showing the progress of the sea ice thickness and concentration "nowcasts", and a comparison of RASM-ESRL sea ice concentration with the University of Hamburg ASI AMSR2 sea ice concentration.
Click to animate
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Isn't the decrease in thickness for the month a consequence of all the thin extent growth for early in the season? If we have new widespread extent, it certainly will be thin to start, lowering the the overall thickness average,
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Isn't the decrease in thickness for the month a consequence of all the thin extent growth for early in the season? If we have new widespread extent, it certainly will be thin to start, lowering the the overall thickness average,
You are probably correct, I was misled by the reduction in the maximum reported thickness.
The CPOM CryoSat-2 sea ice thickness data have been available since 8 October, so here is a comparison between RASM-ESRL and the CPOM 2-day, 1-km product. The difference is calculated as RASM-ESRL minus CPOM thickness.