RASM-ESRL Experimental Sea Ice Forecasts

[Michael]

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/.

url : https://www.esrl.noaa.gov/psd/forecasts/seaice/index.html

[Michael]

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...

[Michael]

...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...

[Michael]

...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

[Michael]

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.

[Michael]

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

[A-Team]

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/

[Michael]

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.

[Michael]

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*

[Michael]

@ Neven :  I had the same problem previously reported with .PNG images with the above animated .GIF.

[Neven]

We're looking into it, Michael. I'll report there that you experience the same problem with an animated GIF.

[DungeonMaster]

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!

[Michael]

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

[echoughton]

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,

[Michael]

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.