To get the data from NSIDC I use, I go to
https://nsidc.org/arcticseaicenews/sea-ice-tools/ where the files listed below can be downloaded. They are in .csv format, i.e. immediately usable in my excel (and excel compatible) files. Daily I use file 1. and file 6.
File 1. has daily extent. The documentation in the file (also see below) confirms it includes a
daily extent sheet
NH-Daily-Extent. The daily data is consistently less than the 5-day extent, which is logical while extent is declining.
But there is no sign of a double-century daily loss. (see attached)
I am confused - so will rely on using one data stream for overall extent - JAXA Extent data (2 day), and NSIDC Area data for what is happening in individual seas.
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NSIDC worksheet Documentation
The Excel workbook contains daily sea ice extent from 1979 to present, in
millions of square kilometers. The eight spreadsheets present single-day extent
values and calculated 5-day trailing average extent values, 5-day trailing
average anomaly, and 5-day trailing average daily change in extent for the
Northern (NH) and Southern (SH) Hemispheres. Blank cells indicate missing
data. Anomalies are compared with the 1981 to 2010 average for that date.
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1. All daily (single day and five-day trailing average) extent values in one file, updated daily (Sea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx)
2. Monthly sea ice average extent and area, and rankings (Sea_Ice_Index_Monthly_Data_with_Statistics_G02135_v3.0.xlsx)
3. Sea ice extent and area organized by year (Sea_Ice_Index_Monthly_Data_by_Year_G02135_v3.0.xlsx)
4. Minimum and maximum extent values and dates for each month and year, with rankings (Sea_Ice_Index_Min_Max_Rankings_G02135_v3.0.xlsx)
5. Sea ice extent rates of change (Sea_Ice_Index_Rates_of_Change_G02135_v3.0.xlsx)
6. Daily sea ice extent, by region (Sea_Ice_Index_Regional_Daily_Data_G02135_v3.0.xlsx)
7. Monthly sea ice extent, by region (Sea_Ice_Index_Regional_Monthly_Data_G02135_v3.0.xlsx)
8. Daily sea ice extent 1981-2010 climatology (N_seaice_extent_climatology_1981-2010_v3.0.csv and S_seaice_extent_climatology_1981-2010_v3.0.csv)