table,column,type,unit,description
gate_daily,gate_id,string,,Gate identifier
gate_daily,date,date,,Day (UTC)
gate_daily,sic_mean,number,fraction,Mean sea-ice concentration over the gate cells that hold a value (0.15 = 15% ice cover). Empty when the day is missing
gate_daily,open_15,boolean,,True when sic_mean is below 0.15. Empty when the day is missing
gate_daily,open_30,boolean,,True when sic_mean is below 0.30. Empty when the day is missing
gate_daily,open_50,boolean,,True when sic_mean is below 0.50. Empty when the day is missing
gate_daily,valid_fraction,number,fraction,Share of the gate's cells that hold a value on this day (n_valid_cells divided by n_cells). A day below 0.5 is missing
gate_daily,provisional,boolean,,True when source is G10016v4
gate_daily,source,string,,NSIDC product for the day: G02202v6 (final) or G10016v4 (near-real-time)
gate_daily,interpolated,boolean,,True when the source marks at least half of the gate cells as filled by interpolation in time. Empty when the day is missing
gate_daily,sic_min,number,fraction,Lowest cell concentration in the gate
gate_daily,sic_max,number,fraction,Highest cell concentration in the gate
gate_daily,sic_std,number,fraction,Standard deviation of cell concentration in the gate (population form)
gate_daily,n_cells,integer,cells,"Ocean cells of the 25 km grid with centers inside the gate, counted on 2020-08-15"
gate_daily,n_valid_cells,integer,cells,Cells inside the gate that hold a concentration value on this day
gate_daily,open_cell_fraction,number,fraction,Share of valid cells with concentration below 0.15
gate_daily,cdr_stdev_mean,number,fraction,Mean over gate cells of the source field cdr_seaice_conc_stdev. Empty when the source has no value
gate_daily,day_of_year,integer,,"Day of year, 1 to 366"
gate_daily,qc_flag,string,,"ok, provisional, low_coverage (valid_fraction below 0.5, day treated as missing) or no_data (the source file holds no value for the gate)"
gate_daily,narrow_gate,boolean,,"True when the channel is narrower than 50 km or the gate has 3 cells or fewer, or by review"
gate_seasons,gate_id,string,,Gate identifier
gate_seasons,year,integer,,Calendar year
gate_seasons,open_days_15,integer,days,Days in the calendar year with open_15 true. Empty when missing_days is above 30 or missing_possibly_open_15 is above 0
gate_seasons,open_days_30,integer,days,Days in the calendar year with open_30 true. Empty when missing_days is above 30 or missing_possibly_open_30 is above 0
gate_seasons,open_days_50,integer,days,Days in the calendar year with open_50 true. Empty when missing_days is above 30 or missing_possibly_open_50 is above 0
gate_seasons,first_open_15,date,,First day of the calendar year with open_15 true. Empty when there is none or open_days_15 is empty
gate_seasons,last_open_15,date,,Last day of the calendar year with open_15 true. Empty when there is none or open_days_15 is empty
gate_seasons,missing_days,integer,days,Days in the calendar year with no sic_mean
gate_seasons,partial,boolean,,True for 1978 (record starts 26 October) and for the year still in progress
gate_seasons,first_open_30,date,,"As first_open_15, at the 30% threshold"
gate_seasons,last_open_30,date,,"As last_open_15, at the 30% threshold"
gate_seasons,first_open_50,date,,"As first_open_15, at the 50% threshold"
gate_seasons,last_open_50,date,,"As last_open_15, at the 50% threshold"
gate_seasons,longest_open_run_15,integer,days,Longest run of consecutive days with open_15 true. A missing day ends a run. Empty when open_days_15 is empty
gate_seasons,longest_run_start_15,date,,First day of that run (the earliest run when several tie)
gate_seasons,longest_run_end_15,date,,Last day of that run
gate_seasons,valid_days,integer,days,Days in the calendar year with a sic_mean
gate_seasons,missing_possibly_open_15,integer,days,"Missing days of the year that could have been open at 15%: the gap lies within 10 days of an open day, or it is longer than 30 days and the gate was open on that calendar day in a year at most 10 years away"
gate_seasons,missing_possibly_open_30,integer,days,"As missing_possibly_open_15, at the 30% threshold"
gate_seasons,missing_possibly_open_50,integer,days,"As missing_possibly_open_15, at the 50% threshold"
gate_seasons,comparable,boolean,,True when the season is not partial and open_days_15 is not empty
gate_seasons,open_days_15_anomaly,number,days,open_days_15 minus the gate mean over comparable seasons 1991 to 2020. Empty when the season is not comparable
gate_seasons,open_days_15_rank,integer,,"Rank of open_days_15 among the gate's comparable seasons, 1 = most open days, ties share the better rank"
gate_climatology,gate_id,string,,Gate identifier
gate_climatology,month,integer,,Calendar month
gate_climatology,day,integer,,Day of month
gate_climatology,n_years,integer,years,Years from 1991 to 2020 with a sic_mean on this calendar day. Missing days are left out of every figure in the row
gate_climatology,sic_mean,number,fraction,Mean of the daily sic_mean over those years
gate_climatology,sic_p10,number,fraction,10th percentile over those years
gate_climatology,sic_median,number,fraction,Median over those years
gate_climatology,sic_p90,number,fraction,90th percentile over those years
gate_climatology,open_15_share,number,fraction,Share of those years with open_15 true on this calendar day
gate_climatology,open_30_share,number,fraction,Share of those years with open_30 true on this calendar day
gate_climatology,open_50_share,number,fraction,Share of those years with open_50 true on this calendar day
gate_trends,gate_id,string,,Gate identifier
gate_trends,threshold,integer,percent,"Concentration threshold: 15, 30 or 50"
gate_trends,start_year,integer,,First season used
gate_trends,end_year,integer,,Last season used
gate_trends,n_seasons,integer,seasons,Full seasons with a count at this threshold
gate_trends,n_excluded,integer,seasons,Full seasons in the period with no count at this threshold
gate_trends,n_zero_seasons,integer,seasons,Seasons used that have zero open days
gate_trends,median_open_days,number,days,Median open days over the seasons used
gate_trends,mean_open_days,number,days,Mean open days over the seasons used
gate_trends,min_open_days,integer,days,Fewest open days in a season used
gate_trends,max_open_days,integer,days,Most open days in a season used
gate_trends,seasons_first_half,integer,seasons,Seasons used before the middle year of the period
gate_trends,open_seasons_first_half,integer,seasons,"Of those, seasons with at least one open day"
gate_trends,seasons_second_half,integer,seasons,Seasons used from the middle year on
gate_trends,open_seasons_second_half,integer,seasons,"Of those, seasons with at least one open day"
gate_trends,ols_days_per_decade,number,days per decade,"Least-squares slope of open days on year, times 10. Empty, with every other slope column, when more than half of the seasons have zero open days: compare the two open_seasons columns instead"
gate_trends,ols_ci95_low,number,days per decade,"Lower end of the 95% interval (Student t, n minus 2 degrees of freedom), assuming independent years"
gate_trends,ols_ci95_high,number,days per decade,Upper end of that interval
gate_trends,ols_p_value,number,,"Two-sided p-value for a zero slope, assuming independent years"
gate_trends,ols_lag1_autocorrelation,number,,"Lag-1 autocorrelation of the residuals, taken in year order"
gate_trends,ols_ci95_low_adjusted,number,days per decade,Lower end of the 95% interval with the sample size reduced to n(1-r)/(1+r) for lag-1 autocorrelation r (equal to ols_ci95_low when r is 0 or negative)
gate_trends,ols_ci95_high_adjusted,number,days per decade,Upper end of that interval
gate_trends,theil_sen_days_per_decade,number,days per decade,"Theil-Sen slope (median of pairwise slopes), times 10"
gate_trends,theil_sen_ci95_low,number,days per decade,Lower end of the 95% interval for the Theil-Sen slope
gate_trends,theil_sen_ci95_high,number,days per decade,Upper end of the 95% interval for the Theil-Sen slope