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Wipneus
Netherlands
Recent Activity
PIOMAS update: Latest value: 2014-2-28 20.86 I have updated my graphics at ArctischePinguin for the latest data. Monthly Data Daily Anomalies Daily data
3. Is river water anything to do with this strange arrival of open water in ESAS? http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r04c05.2014065.terra idunno, it is Laptev Sea. West, with the Severnaya Zemlya islands on the lower left. See https://forum.arctic-sea-ice.net/index.php/topic,382.msg21111.html#msg21111 how the open water formed. It is wind, not river warmth. As it happens, there is a clear first Landsat 8 image of the area. I will post it in the Image-of-the-day thread on the forum.
I'm not sure whether the PIOMAS sea ice volume anomaly graph has also been upgraded to Version 2.1 (it says V2 in the file name), There are two files, named: BPIOMASIceVolumeAnomalyCurrentV2.1.png and: BPIOMASIceVolumeAnomalyCurrentV2.png but they appear identical in my eyes, and both say: "Version: IC-SST 2.1" Comparing with last months version, the downward spikes (I think you know what I mean) are a bit smaller now.
I have posted an animation of ASI AMSR2 ice concentration (from Uni Hamburg data) on the forum (registration required): https://forum.arctic-sea-ice.net/index.php/topic,382.msg18817/topicseen.html#msg18817
"no update for 2014 yet from Uni Hamburg." And that is still true today. Lots of my own scripts were not 2014-ready, so I guess something similar is the case there.
Toggle Commented Jan 5, 2014 on Merry christPIOMAS at Arctic Sea Ice
My PIOMAS graphics update announcement has, as usual, landed in the spam box. They are to be found in the usual place. [released now, thanks for the heads-up; N.]
Toggle Commented Dec 4, 2013 on In memoriam: Albert A. Bartlett at Arctic Sea Ice
Does anyone know why there is such a big difference between the daily ice extent from NSIDC : Look at the differences between Svalbard and Bering Strait... That grey between Svalbard and Bering Strait means it is unavailable, caused by the data problems with the DMSP F17 satellite. Discussed on the forum in the NSIDC tread.
Here is the today's ice cover compared with last year, seen by AMSR2 and processed by Jaxa. Blue is concentration now above 15% and below last year. Red is the reverse. I am placing such images with some regularity on the forum. It is more convenient for me, and Typepad seems to particularly dislike me which is not encouraging.
Toggle Commented Sep 9, 2013 on PIOMAS September 2013 at Arctic Sea Ice
Forcings are proportional to log(concentration), so a doubling of methane from 1->2 ppm, compared with CO2 concentration of 390->391 ppm gives a forcing ratio of: (log(2)*.8)/(log(391/390)*4.5) = 48.1 close enough to 54?
" So forcing for a doubling of CH4 is only 0.47 W/m^2. Did I do that right now ? " From a previous discussion: http://neven1.typepad.com/blog/2011/12/arctic-methane-russian-researchers-report/comments/page/2/#comments a link to RC: http://www.realclimate.org/index.php/archives/2010/12/losing-time-not-buying-time/ You are getting closer, Raypierre gives a value of 0.8 W/m2 per doubling.
Neven: The good news is that the SSMIS 12.5km data has started to come in again. Unless "ocean masks" are going to to be applied there as well, I can make regional graphs from the SSMIS data as well.
Toggle Commented Jul 6, 2013 on So, how slow was this start? at Arctic Sea Ice
Am I the only one that noticed the thickness graph did not update (ends in May) at all?
Toggle Commented Jul 6, 2013 on PIOMAS July 2013 at Arctic Sea Ice
Chris, it would indeed be nice to have it earlier. The July data would come too late to use it for the Sea Ice Outlook projections.
Toggle Commented Jun 5, 2013 on PIOMAS June 2013 at Arctic Sea Ice
Alexander Beitsch informed me that he has changed the plotting routines: Most of how it has been has internal or somewhat "historical" reasons internal to our institute. Changes include: 1) everything is PNGs now; 2) I reduced single file sizes by reducing the image depth; 3) I use a single contrasting color ("coral") for continents; Alexander and other team members intend to look into possibilities to reduce the graphic sizes even further in the coming weeks. Repeated message: these data are not officially released and work in-progress. Indeed the sizes are now 2MB, not much larger than the files I produce. I will continue produce mine for some time longer until things have stabilized on their FTP server: ftp://ftp-projects.zmaw.de/seaice/AMSR2/
Toggle Commented Jun 4, 2013 on New map on the block at Arctic Sea Ice
BTW, the well know regions map from the Cryosphere Today: This map uses the same mapping as the Uni Hamburg with pixel scaling of 25km (1:8). So you can do your regional calculations as well.
Toggle Commented Jun 3, 2013 on If this is real... at Arctic Sea Ice
Both NSIDC and Uni Hamburg document the area/extent calculation using the real grid cell area. But I just remembered the fact that Jaxa/IJIs values are all multiples of 12.5^2. That means they don't. It should be visible in the annual extent curves.
Toggle Commented Jun 1, 2013 on If this is real... at Arctic Sea Ice
SATire: NSIDC has grid cell area's on http://nsidc.org/data/polar_stereo/tools_geo_pixel.htm From psn06area_v3.dat a 6.25km grid: Horizontal is the 6.25^2 nominal area. Real cell area's can differ quite a bit and should be used.
Toggle Commented Jun 1, 2013 on If this is real... at Arctic Sea Ice
I forgot to mention: The ASMR2 maps from May 11-14 are both missing from JAXA/IJIS and the Bremen websites. However these (from Hamburg) are present, and from the file times where updated at the times. This is consistent with something happening with the processing at JAXA while low level data still being made available. This in contrast with speculations that the spacecraft was in some safe mode for incoming solar flares.
Toggle Commented May 30, 2013 on ASI 2013 update 1: a slow start at Arctic Sea Ice
A-Team: Do you know the url for the satellite image itself that they are using? Before they apply the sea ice concentration algorithm. I'm not seeing anything at this resolution at Jaxa AMSR. I don't know any other data. But I have just read the introduction of Spreen et al 2008, where they are calculating ice concentration data from swath data and thereafter interpolated into the desired geographical grid. Those results from swath data are compared with calculations on Level 3 gridded brighness temperatures from NSIDC. I short: what you are looking for may not exist.
Toggle Commented May 30, 2013 on ASI 2013 update 1: a slow start at Arctic Sea Ice
A-Team: To make sure you have the same information as I do, this is the header of the NetCDF file (the metadata part): netcdf Arc_20130201_res3.125_pyres { dimensions: x = 2432 ; y = 3584 ; time = UNLIMITED ; // (1 currently) variables: double x(x) ; x:standard_name = "grid_longitude" ; x:long_name = "x coordinate of projection (eastings)" ; x:units = "none (index variable)" ; x:axis = "X" ; double y(y) ; y:standard_name = "grid_latitude" ; y:long_name = "y coordinate of projection (northings)" ; y:units = "none (index variable)" ; y:axis = "Y" ; double time(time) ; time:standard_name = "time" ; time:units = "days since 1-01-01 00:00:00" ; time:calendar = "proleptic_gregorian" ; short sea_ice_concentration(time, y, x) ; sea_ice_concentration:standard_name = "sea_ice_area_fraction" ; sea_ice_concentration:long_name = "daily averaged total ice concentration" ; sea_ice_concentration:units = "%" ; sea_ice_concentration:scale_factor = 100. ; sea_ice_concentration:description = "Sea ice area fraction is area of the sea surface occupied by sea ice." ; sea_ice_concentration:source = "AMSR2 Sea Ice Concentration, Institute for Oceanography, University of Hamburg" ; sea_ice_concentration:range = "0-10000" ; sea_ice_concentration:scale_factor_comment = "divide by 100 to recieve 0-100%" ; sea_ice_concentration:date = "Daily averaged sea ice concentration for 2013-02-01" ; // global attributes: :CDI = "Climate Data Interface version 1.6.0 (http://code.zmaw.de/projects/cdi)" ; :Conventions = "CF-1.4" ; :history = "Wed Apr 24 20:12:09 2013: cdo setdate,2013-02-01 -settime,12:00:00 /scratch/local1/u241125/SEA_ICE_CONCENTRATION/AMSR2/3.125km/Arc_20130201_res3.125_pyres_temp.nc /scratch/local1/u241125/SEA_ICE_CONCENTRATION/AMSR2/3.125km/Arc_20130201_res3.125_pyres.nc\n", "Created Wed Apr 24 20:12:09 2013" ; :grid_resolution = "3.125 km" ; :description = "gridded ASI AMSR2 sea ice concentration" ; :algorithm = "ASI v5" ; :title = "Daily averaged Arctic sea ice concentration derived from AMSR2 L1R brightness temperature measurements" ; :landmask_value = "12500" ; :tiepoints = "P0=47 K, P1=11.7 K" ; :gridding_method = "Nearest Neighbor, with Python package pyresample" ; :Comment1 = "Scaled land mask value is 12500, NaN values are masked 11500" ; :Comment2 = "After downscaling (divide by 100): land mask value is 125, NaN values are masked 115" ; :hemisphere = "North" ; :contact = "xxxxxxxxxxxx" ; :netCDF_created_by = "Alexander Beitsch, xxxxxxxxxxx" ; :datasource = "JAXA" ; :offset = "0" ; :grid = "NSIDC polar stereographic with tangential plane at 70degN , see http://nsidc.org/data/polar_stereo/ps_grids.html" ; :missing_value = "11500" ; :sensor = "AMSR2" ; :cite = "Spreen, G., L. Kaleschke, G. Heygster, Sea Ice Remote Sensing Using AMSR-E 89 GHz Channels, J. Geophys. Res., 113, C02S03, doi:10.1029/2005JC003384, 2008." ; :geocorrection = "none" ; :CDO = "Climate Data Operators version 1.6.0 (http://code.zmaw.de/projects/cdo)" ; data:
Toggle Commented May 30, 2013 on ASI 2013 update 1: a slow start at Arctic Sea Ice
The Ice and Snow data page from the KlimaCampus of the University of Hamburg marks as "New New New..." some AMSR2 ice concentration images and data. Sample image: ftp://ftp-projects.zmaw.de/seaice/AMSR2/Arc_latest_yesterday_AMSR2_color_3.125km.jpg (AMSR2 Arctic sea ice concentration on a 3.125 km grid, highest resolution anywhere AFAIK)
Toggle Commented May 27, 2013 on ASI 2013 update 1: a slow start at Arctic Sea Ice
For the arctic, I would suspect that the cold bias exhibited in many models may be a problem.. dunno. You could start first looking how well the volume of ice is modeled. As seen in: volume of CMIP5 models vary from something like 2.5 too much to 6 (!) times too little in 1980. So the first question is, are the models that have too much (little) sea ice volume the same that have absolute temps too low (high) ? My CMIP5 page in development : https://sites.google.com/site/arctischepinguin/home/cmip5
Toggle Commented May 6, 2013 on PIOMAS May 2013 at Arctic Sea Ice
I have updated my graphics, announcement in the spam box :-( [Released. Thanks, Wipneus. N.] It seems that now even posts without any links can be considered as s p a m. Or is using that word considered suspect?
Toggle Commented May 4, 2013 on PIOMAS May 2013 at Arctic Sea Ice
Wayne, now that you are mentioning ice crystals: This morning spaceweather.com showed an unusual elliptical moon halo: Bigger pic at http://spaceweather.com/gallery/indiv_upload.php?upload_id=80972 In the comment: Atmospheric optics expert Les Cowley comments on the apparition: "There have been quite a few ellipticals seen in the last few weeks both in Europe and the US. Something strange [is happening] in all our skies!" "These unusual ice halos are much smaller than the ordinary 22 degree halo encircling the sun or moon," Cowley continues. "In the 22 degree halo the ring is effectively made by light refracting through a 60 degree ice prism. The smaller elliptical halos need much narrower prisms and we think that six sided plate shaped crystals with very shallow pyramidal ends might do the work. The problem is that such crystals are unphysical and computer simulations using them do not predict the halo very well. An alternative is the wedge shaped sections of small snowflake-like crystals. Whatever their cause, they are rare and mysterious!" Myself I wonder if any form of regular crystal shape can produce such a continuous aberration. But I also wonder if it is something you have any knowledge of?
Toggle Commented Apr 25, 2013 on Perception of the Arctic at Arctic Sea Ice
A-Team: PIOMAS gridded data comes as rectangle arrays, sized 360x120, when appropriate with added dimensions for month (12) and year (35). One array is the average thickness, another the concentration per grid cell. The plot is simply a scatter plot with x the thickness and y the concentration. I chose for one month, as I suspect any relation between thickness and concentration may depend on the melt/freezing state of the ice. I choose for 5 years to make those boundaries nicely visible. Those lines, sharp edge as you call the one on the left, are in the data. Some of them must be modeling artifacts. Blue line is a smooth curve. Normally I use the default from the plotting library that I use (ggplot2) which is a Loess, smooth. This time I got a warning, that because of the large number of data points, a "gam" smooth was used. I have no experience with "gam" smooths, but forcing the method to "Loess" did give after twenty minutes of calculation a very similar plot. So I left it at that. BTW, the dots are plotted with transparent color (so the ink won't blot the image) enabled. I do not know how the alpha channel survives until you have come to dissect the image.
Toggle Commented Apr 17, 2013 on PIOMAS April 2013 - extra update at Arctic Sea Ice