SE.ACMF Meteorological observations - Minimum cloud base, hourly values
Description
Purpose: Describes the current weather and, over time, the climate. Basis for forecast verification
Unit: Eighths for cloud amount and meters for cloud base.
Characteristics:
In the official network of observations in Sweden there are several stations that report cloud quantity and cloud base at an hourly interval. These stations are equipped with cloud altimeters that measure the height to the underside of the clouds. The amount of cloud is determined by an advanced algorithm in the measuring instrument.
Most of the measuring stations send fully automatic reports and in the case of clouds, all cloud layers detected by the instrument are reported. Up to 4 cloud layers can be reported.
For manual stations, which are then mainly historical observations, the following applies:
- Lowest cloud layer regardless of its cloud quantity, to be reported at least 1/8.
- Next, higher layers of cloud covering a total of 3/8 or more of the sky.
- Next, higher layers of cloud covering a total of 5/8 or more of the sky.
Cumulonimbus clouds not reported in accordance with points 1, 2 or 3 are always reported in a separate group regardless of the amount of cloud. This is especially true of historical manual observations. Today's measuring instruments cannot distinguish such clouds.
The cloud base to the above cloud layer is also reported.For example, a station can report 1/8 with cloud base 300 m, 3/8 with cloud base 500 m and 5/8 with cloud base 1000 m.
- Not all layers of cloud are always reported as the above regulatory framework must be met.
- The unit of cloud quantity is eighths where 0/8 is cloudless, 8/8 is cloudless. 9/8 means that the cloudy sky cannot be observed due to fog or high snow drift. At 9/8, the term vertical visibility is instead used, which indicates how far vertically it is possible to see.
Unit for cloud base and vertical visibility is meters.
Cloud quantity
- Data is available with values 0 to 9.
- Values 10 to 15 are for data received in the form of aerodrome observations (METAR), such data are not included in this dataset. These values will be empty and therefore cannot be used.
- Value 0 to 8 means 0 to 8 eighths.
- Value 9 means that the cloudy sky cannot be observed due to fog or high snow drift. Instead of cloud base is then indicated vertical visibility.
Cloud base
Cloud base refers to the vertical distance from the ground to the underside of the clouds. Unit of meter.
Parameter 36
Last measured cloud base at every full hour.
Network information:
- SMHI's station network: Data is collected and stored in SMHI's databases. Data quality is checked, which means that incorrect data is corrected and that data loss is supplemented based on expert judgement where possible. Most of the stations are continuously monitored, inspected and maintained by SMHI.
- Other stations: Data is collected and stored in SMHI's databases. The data quality is unknown to SMHI as SMHI does not perform quality control on data or inspections at the stations.
Quality codes: Green values (G) mean approved quality. Yellow values (Y) mean data that may be suspiciously inaccurate. It can also be an aggregated value based on other metrics.
Boundaries: 0 to 7500 m (cloud base)
For more info see: https://www.smhi.se/Knowledge Bank/Cloud and Cloud Management-1.1514
Resources
| Name |
Format |
Description |
Link |
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0 |
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https://www.smhi.se/data/hitta-data-for-en-plats/ladda-ner-vaderobservationer/lowestCloudBaseInstant |
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0 |
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https://opendata-view.smhi.se/met-obs/ACMF.lagsta_molnbas_timme_view/wms?service=wms&request=getcapabilities |
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0 |
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https://opendata-download-metobs.smhi.se/api/version/latest/parameter/36.json, https://opendata-download-metobs.smhi.se/api/inspire/metobs-36.atom |