viewof source = dahlem_climate
.derive({ year: d => +op.substring(d.MESS_DATUM_BEGINN, 0, 4) })
.select({ year: 'year', JA_RR: 'precipitation', JA_TT: 'temperature' })
.filter(d => d.precipitation >= 0 && d.temperature >= 0)
.derive({ temperature_mean: d => op.mean(d.temperature) })
.derive({ precipitation_mean: d => op.mean(d.temperature) })
.view()