artic = aq.from(await FileAttachment("artic-sea-ice.csv").csv())
.derive({year: d => +d.year,
month: d => +d.month,
day: d => +d.date,
sea_ice_extent_km2: d => +d['SeaIceExtent[km2]']})
.derive({ day_of_year: d => aq.op.dayofyear(aq.op.datetime(d.year, d.month-1, d.day))})
.select(aq.not('time[second]', 'SeaIceExtent[km2]', 'date', '#num'))
.filter(d => d.year > 1988).reify()
.orderby(["year", "month", "day"])