{
 "schema": "nephos.method.v1",
 "slug": "van-breen-frozen-amstel-1611",
 "title": "Adam van Breen, Skating on the Frozen Amstel River (1611), NGA 2010.20.1",
 "urls": [
  "/studies/van-breen-frozen-amstel-1611"
 ],
 "written": {
  "summary": "Dated “16011” on the gable of the house, read by NGA as 1611. The catalogue identifies the Amstel just south of Amsterdam and links skating scenes to severe winters; an NGA article places the panel amid chilly winters. The date fixes the making, not the winter shown.",
  "items": [
   {
    "quote": "on gable of manor house: 16011",
    "source": "NGA object record, Inscriptions.",
    "url": "https://www.nga.gov/artworks/150754-skating-frozen-amstel-river"
   },
   {
    "quote": "likely in part due to a series of severe winters in the Low Countries",
    "source": "Libby (2017), on why skating scenes were popular in the first half of the century.",
    "url": "https://www.nga.gov/research/publications/online-editions/dutch-paintings-seventeenth-century-skating-frozen-amstel"
   },
   {
    "quote": "amid a sequence of chilly winters in the Low Countries",
    "source": "Degroot, NGA (2023), on Van Breen’s painting.",
    "url": "https://www.nga.gov/stories/articles/painting-climate-change-17th-century"
   },
   {
    "quote": "winter was even colder",
    "source": "Degroot, NGA (2023), on 1646, the year of Van Goyen’s NGA ice scene.",
    "url": "https://www.nga.gov/stories/articles/painting-climate-change-17th-century"
   }
  ]
 },
 "records": [
  {
   "name": "KNMI winter categories, Low Countries (van Engelen, Buisman and IJnsen)",
   "detail": "A documentary reconstruction compiled by historians for the November–March season, one category per winter. Regional, not an observation on the Amstel.",
   "url": "https://cdn.knmi.nl/knmi/map/page/klimatologie/gegevens/daggegevens/antieke_wrn/nederland_wi_zo.zip"
  },
  {
   "name": "David Fabricius’s diary at Osteel, counted by Lenke (1968)",
   "detail": "Frost days by month from a written diary about 205 km north-east of Amsterdam. It also fed the KNMI estimates for these years.",
   "url": "https://dwdbib.dwd.de/retrosammlung/download/pdf/38758#page=34"
  }
 ],
 "gaps": [
  "No thermometer or daily register for Amsterdam in 1610–11 has been found; KNMI’s inventory of Dutch instrumental series starts at the end of the 17th century.",
  "No source consulted records ice on the Amstel in a particular week of 1610–11, or dates any session on the panel.",
  "Buisman’s descriptive volume for 1575–1700 and the Landsman articles were not consulted; the NGA systematic catalogue entry was."
 ],
 "tests": [
  {
   "claim": "Were the winters on either side of the date severe?",
   "result": "No. KNMI classes 1610–11 and 1611–12 as 6, “Cold”, one step below “Severe”. The last “Very severe” winter before the date was 1607–08."
  },
  {
   "claim": "Was the panel made amid a sequence of chilly winters?",
   "result": "Yes in this classification: 3 consecutive winters, 1609–10 to 1611–12, are category 6 or colder."
  },
  {
   "claim": "Was 1646 colder still?",
   "result": "The winter ending in 1646 is 7, “Severe”, one step above 1610–11. The winter that began late in 1646 returns to 6."
  },
  {
   "claim": "Did severe winters recur in the first half of the century?",
   "result": "9 of 50 winters in 1601–1650 are “Severe” or harsher, against 16 of 50 in 1651–1700. None in 1601–1650 is milder than “Fairly mild”."
  },
  {
   "claim": "What did one observer count?",
   "result": "Fabricius’s diary gives 58 frost days for 1610–11, rank 12 of 19 winters, most first; January 1611 alone had 22."
  }
 ],
 "finding": "The reconstruction supports a run of chilly winters around the date, as the NGA article says, and a frost spell from late December 1610 into January 1611 in East Frisia. It does not show a severe winter in 1611, and nothing dates the ice in the picture.",
 "verdicts": [
  {
   "claim": "A sequence of chilly winters around 1611",
   "verdict": "Partially agrees",
   "reason": "Three consecutive “Cold” winters in a regional documentary reconstruction; not an observation at Amsterdam."
  },
  {
   "claim": "A series of severe winters behind skating scenes",
   "verdict": "Partially agrees",
   "reason": "Severe winters recur in 1601–1650, but more fall in 1651–1700; weather records cannot test why the scenes sold."
  },
  {
   "claim": "The painted day and the Amstel’s ice",
   "verdict": "Unknown",
   "reason": "The date fixes the making of the panel. No record links the scene to a particular winter or week."
  }
 ],
 "limits": [
  "KNMI C_win: a nine-step documentary classification of the November–March season for the Low Countries, from 1 (extremely mild) to 9 (extremely severe). It is compiled evidence, not an observation at Amsterdam.",
  "The classification divides the 284 instrumental winters of 1707–1990 symmetrically around 5; its printed frequencies are reproduced by the file’s own 1707–1990 rows. The reference period itself lies largely within the Little Ice Age.",
  "Fabricius frost days are Lenke’s counts from a written diary, including days inferred within frost spells; they are not thermometer readings.",
  "The Lenke pages consulted do not state whether diary dates were converted between calendars. A ten-day Julian offset would move the 23 December–26 January spell to about 2 January–5 February.",
  "Lenke counts are from Osteel, East Frisia, about 205 km from Amsterdam, and they contributed to the KNMI estimates for 1591–1613.",
  "The NGA entry suggests the Zuiderkerk tower may have been revised after its spire was added in 1614, so work on the panel may not be confined to 1611."
 ]
}