pvlib.iotools.read_tmy2#

pvlib.iotools.read_tmy2(filename)[source]#

Read a TMY2 file into a DataFrame.

Note that values contained in the DataFrame are unchanged from the TMY2 file (i.e. units are retained). Time/Date and location data imported from the TMY2 file have been modified to a “friendlier” form conforming to modern conventions (e.g. N latitude is postive, E longitude is positive, the “24th” hour of any day is technically the “0th” hour of the next day). In the case of any discrepencies between this documentation and the TMY2 User’s Manual 1, the TMY2 User’s Manual takes precedence.

Parameters

filename (str) – A relative or absolute file path.

Returns

  • Tuple of the form (data, metadata).

  • data (DataFrame) – A dataframe with the columns described in the table below. For a more detailed descriptions of each component, please consult the TMY2 User’s Manual 1, especially tables 3-1 through 3-6, and Appendix B.

  • metadata (dict) – The site metadata available in the file.

Notes

The returned structures have the following fields.

key

description

WBAN

Site identifier code (WBAN number)

City

Station name

State

Station state 2 letter designator

TZ

Hours from Greenwich

latitude

Latitude in decimal degrees

longitude

Longitude in decimal degrees

altitude

Site elevation in meters

field

description

index

Pandas timeseries object containing timestamps

year

month

day

hour

ETR

Extraterrestrial horizontal radiation recv’d during 60 minutes prior to timestamp, Wh/m^2

ETRN

Extraterrestrial normal radiation recv’d during 60 minutes prior to timestamp, Wh/m^2

GHI

Direct and diffuse horizontal radiation recv’d during 60 minutes prior to timestamp, Wh/m^2

GHISource

See 1, Table 3-3

GHIUncertainty

See 1, Table 3-4

DNI

Amount of direct normal radiation (modeled) recv’d during 60 mintues prior to timestamp, Wh/m^2

DNISource

See 1, Table 3-3

DNIUncertainty

See 1, Table 3-4

DHI

Amount of diffuse horizontal radiation recv’d during 60 minutes prior to timestamp, Wh/m^2

DHISource

See 1, Table 3-3

DHIUncertainty

See 1, Table 3-4

GHillum

Avg. total horizontal illuminance recv’d during the 60 minutes prior to timestamp, units of 100 lux (e.g. value of 50 = 5000 lux)

GHillumSource

See 1, Table 3-3

GHillumUncertainty

See 1, Table 3-4

DNillum

Avg. direct normal illuminance recv’d during the 60 minutes prior to timestamp, units of 100 lux

DNillumSource

See 1, Table 3-3

DNillumUncertainty

See 1, Table 3-4

DHillum

Avg. horizontal diffuse illuminance recv’d during the 60 minutes prior to timestamp, units of 100 lux

DHillumSource

See 1, Table 3-3

DHillumUncertainty

See 1, Table 3-4

Zenithlum

Avg. luminance at the sky’s zenith during the 60 minutes prior to timestamp, units of 10 Cd/m^2 (e.g. value of 700 = 7,000 Cd/m^2)

ZenithlumSource

See 1, Table 3-3

ZenithlumUncertainty

See 1, Table 3-4

TotCld

Amount of sky dome covered by clouds or obscuring phenonema at time stamp, tenths of sky

TotCldSource

See 1, Table 3-5

TotCldUncertainty

See 1, Table 3-6

OpqCld

Amount of sky dome covered by clouds or obscuring phenonema that prevent observing the sky at time stamp, tenths of sky

OpqCldSource

See 1, Table 3-5

OpqCldUncertainty

See 1, Table 3-6

DryBulb

Dry bulb temperature at the time indicated, in tenths of degree C (e.g. 352 = 35.2 C).

DryBulbSource

See 1, Table 3-5

DryBulbUncertainty

See 1, Table 3-6

DewPoint

Dew-point temperature at the time indicated, in tenths of degree C (e.g. 76 = 7.6 C).

DewPointSource

See 1, Table 3-5

DewPointUncertainty

See 1, Table 3-6

RHum

Relative humidity at the time indicated, percent

RHumSource

See 1, Table 3-5

RHumUncertainty

See 1, Table 3-6

Pressure

Station pressure at the time indicated, 1 mbar

PressureSource

See 1, Table 3-5

PressureUncertainty

See 1, Table 3-6

Wdir

Wind direction at time indicated, degrees from east of north (360 = 0 = north; 90 = East; 0 = undefined,calm)

WdirSource

See 1, Table 3-5

WdirUncertainty

See 1, Table 3-6

Wspd

Wind speed at the time indicated, in tenths of meters/second (e.g. 212 = 21.2 m/s)

WspdSource

See 1, Table 3-5

WspdUncertainty

See 1, Table 3-6

Hvis

Distance to discernable remote objects at time indicated (7777=unlimited, 9999=missing data), in tenths of kilometers (e.g. 341 = 34.1 km).

HvisSource

See 1, Table 3-5

HvisUncertainty

See 1, Table 3-6

CeilHgt

Height of cloud base above local terrain (7777=unlimited, 88888=cirroform, 99999=missing data), in meters

CeilHgtSource

See 1, Table 3-5

CeilHgtUncertainty

See 1, Table 3-6

Pwat

Total precipitable water contained in a column of unit cross section from Earth to top of atmosphere, in millimeters

PwatSource

See 1, Table 3-5

PwatUncertainty

See 1, Table 3-6

AOD

The broadband aerosol optical depth (broadband turbidity) in thousandths on the day indicated (e.g. 114 = 0.114)

AODSource

See 1, Table 3-5

AODUncertainty

See 1, Table 3-6

SnowDepth

Snow depth in centimeters on the day indicated, (999 = missing data).

SnowDepthSource

See 1, Table 3-5

SnowDepthUncertainty

See 1, Table 3-6

LastSnowfall

Number of days since last snowfall (maximum value of 88, where 88 = 88 or greater days; 99 = missing data)

LastSnowfallSource

See 1, Table 3-5

LastSnowfallUncertainty

See 1, Table 3-6

PresentWeather

See 1, Appendix B. Each string contains 10 numeric values. The string can be parsed to determine each of 10 observed weather metrics.

References

1(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45)

Marion, W and Urban, K. “Wilcox, S and Marion, W. “User’s Manual for TMY2s”. NREL 1995. DOI: 10.2172/87130