Field Dictionary

The data file contains 19 fields, described below in five groups: site identifiers, wind, surface elements, cloud cover, and solar radiation. Field names are case-sensitive.

Site Identifier & Location

#	Field	Type	Unit	Description
1	farm_id	string	—	Unique site ID (sample: HuaR_093)
2	date_time	string	—	Forecast valid time, Beijing time, 15-minute steps
3	lat	decimal	°	Latitude, north positive, sample 36.35208
4	lon	decimal	°	Longitude, east positive, sample 102.95839

Wind

#	Field	Type	Unit	Description
5	spd10	decimal	m/s	10 m wind speed (sample range 0.1 – 3.4)
6	dir10	decimal	°	10 m wind direction, meteorological (direction from), north = 0°, clockwise, 0 – 360
7	spd100	decimal	m/s	100 m wind speed (near turbine hub height; sample range 0.02 – 5.4)
8	dir100	decimal	°	100 m wind direction, defined as dir10

Surface Elements

#	Field	Type	Unit	Description
9	sp	decimal	Pa	Surface pressure. Sample 79658 – 80630 Pa (≈ 797 – 806 hPa), ≈ 2000 m elevation; divide by 100 for hPa
10	t2m	decimal	K	2 m temperature, Kelvin; Celsius = K − 273.15. Sample 282.2 – 298.6 K, i.e. 9.1 – 25.5 ℃
11	rh2	decimal	%	2 m relative humidity, 0 – 100 (sample can saturate to 100)

Cloud Cover

#	Field	Type	Unit	Description
12	lcc	decimal	0-1	Low cloud fraction
13	mcc	decimal	0-1	Mid cloud fraction
14	hcc	decimal	0-1	High cloud fraction
15	tcc	decimal	0-1	Total cloud fraction

Cloud fractions are 0-1 and may slightly exceed bounds

Cloud values are fractions between 0 and 1, not percentages. Due to grid interpolation they may slightly exceed the range (sample observed −0.18 to 1.13); downstream users are advised to clip to [0, 1].

Solar Radiation (accumulated from the issue time)

#	Field	Type	Unit	Description
16	dr	decimal	J/m²	Direct radiation (inferred DNI — direct normal irradiance)
17	sr	decimal	J/m²	Diffuse radiation (DHI)
18	rr	decimal	J/m²	Reflected radiation (surface-reflected shortwave; not precipitation)
19	tr	decimal	J/m²	Global radiation (GHI on the horizontal plane)

Accumulated values — must be differenced before use

All four radiation fields are energy density monotonically accumulated from the issue time (+0h) (J/m²); the 1441-row sample shows zero decreases. Rules of use:

1. Mean irradiance (W/m²) over an interval requires differencing: W/m² = (accumulated end − accumulated start) ÷ interval seconds — ÷ 900 for 15-minute steps. E.g. tr rising from 4598361 to 4598457 gives ≈ 0.1 W/m² mean over that 15 minutes.
2. Nighttime values plateau (unchanged) and can directly indicate sunrise / sunset periods.
3. Inter-field observational relations (for data checking): rr ≈ 0.216 × tr (surface albedo ≈ 0.216); dr + sr ≈ 1.21 × tr.
4. The exact radiation geometry (normal vs. horizontal projection) and units should be confirmed in writing with the data provider and fixed in your integration config.