This is Wipneus's Typepad Profile.
Join Typepad and start following Wipneus's activity
Join Now!
Already a member? Sign In
Wipneus
Netherlands
Recent Activity
Landsat 8 orbits are repeated exactly every 16 days. So if you have a successful image look for image 16 (32,...) days later. Places in the polar regions appear in multiple paths, also the ascending (night) half of each orbit can be used in summer. So there may be more image series to be found. Because the position of the satellite differs, there will be distortions with the elevation of the surface. I don't know if you have already found this. The acquisition schedule (for June) is here: http://landsat.usgs.gov/tools_pend_acq_l8.php?path=/L8_Pend_Acq/y2014/Jun Last time I looked the usefulness was very limited: many images on the list are don't become available but also the reveres is true.
Data - the one problem I have is with netcdf format. Panoply handles it, but doing math on the data can't be done in Panoply. Flat binary and csv are fine in Excel (flat binary can be handled easily in Excel VBA - I'm a programming dunce and I manage it). ncdump gives a csv representation of the contents of netcdf files. https://www.unidata.ucar.edu/software/netcdf/docs/netcdf/ncdump.html
Toggle Commented May 15, 2014 on SIPN presentation at Arctic Sea Ice
Lodger: yes Neven notified me of dr Schweigers post. I am glad we are able do something useful in return for (and with) all the data we get every month.
Toggle Commented May 14, 2014 on PIOMAS May 2014 at Arctic Sea Ice
Hi everybody, I have been absent due to a broken telephone cable. Coming back I noticed that after I wrote this about the PSC thickness graph: The PSC graph shows average grid cell thickness. That is they add up all grid cell thickness measures and divide that by the number of grid cells. So it is not a true area-averaged number: the smaller grid cells have a relative overweight. The next day PSC changed the graph! I haven't looked at it in detail, but would not be surprised if the average is now more area-weighted and perhaps more in line with Neven's graph.
Toggle Commented May 13, 2014 on PIOMAS May 2014 at Arctic Sea Ice
The Polar Science Center thickness graph looks a lot different this month, with 2014 jutting out a lot more above the other post-2010 years. It has something to do with how they calculate average thickness, but I forgot the details: The PSC graph shows average grid cell thickness. That is they add up all grid cell thickness measures and divide that by the number of grid cells. So it is not a true area-averaged number: the smaller grid cells have a relative overweight. Those small grid cells are near the grid pole: in the northern half of Greenland. This fits nicely with observations that more thick ice near Greenland and Canadian Archipelago is found this year. We will be able to check this when/if the gridded daily data from April will become available as well.
Toggle Commented May 8, 2014 on PIOMAS May 2014 at Arctic Sea Ice
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