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kandersolarkandersolar
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move calculate_deltat from pvlib.spa to pvlib.solarposition
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‎docs/sphinx/source/reference/solarposition.rst

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -29,7 +29,7 @@ Additional functions for quantities closely related to solar position.
2929
solarposition.calc_time
3030
solarposition.pyephem_earthsun_distance
3131
solarposition.nrel_earthsun_distance
32-
spa.calculate_deltat
32+
solarposition.calculate_deltat
3333

3434

3535
Functions for calculating sunrise, sunset and transit times.

‎pvlib/solarposition.py

Lines changed: 151 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -306,7 +306,7 @@ def spa_python(time, latitude, longitude,
306306
avg. yearly air temperature in degrees C.
307307
delta_t : float, optional, default 67.0
308308
Difference between terrestrial time and UT1.
309-
If delta_t is None, uses spa.calculate_deltat
309+
If delta_t is None, uses :py:func:`calculate_deltat`
310310
using time.year and time.month from pandas.DatetimeIndex.
311311
For most simulations the default delta_t is sufficient.
312312
*Note: delta_t = None will break code using nrel_numba,
@@ -370,7 +370,7 @@ def spa_python(time, latitude, longitude,
370370

371371
spa = _spa_python_import(how)
372372

373-
delta_t = delta_t or spa.calculate_deltat(time.year, time.month)
373+
delta_t = delta_t or calculate_deltat(time.year, time.month)
374374

375375
app_zenith, zenith, app_elevation, elevation, azimuth, eot = \
376376
spa.solar_position(unixtime, lat, lon, elev, pressure, temperature,
@@ -412,7 +412,7 @@ def sun_rise_set_transit_spa(times, latitude, longitude, how='numpy',
412412
to machine code and run them multithreaded.
413413
delta_t : float, optional, default 67.0
414414
Difference between terrestrial time and UT1.
415-
If delta_t is None, uses spa.calculate_deltat
415+
If delta_t is None, uses :py:func:`calculate_deltat`
416416
using times.year and times.month from pandas.DatetimeIndex.
417417
For most simulations the default delta_t is sufficient.
418418
*Note: delta_t = None will break code using nrel_numba,
@@ -449,7 +449,7 @@ def sun_rise_set_transit_spa(times, latitude, longitude, how='numpy',
449449

450450
spa = _spa_python_import(how)
451451

452-
delta_t = delta_t or spa.calculate_deltat(times.year, times.month)
452+
delta_t = delta_t or calculate_deltat(times.year, times.month)
453453

454454
transit, sunrise, sunset = spa.transit_sunrise_sunset(
455455
unixtime, lat, lon, delta_t, numthreads)
@@ -974,7 +974,7 @@ def nrel_earthsun_distance(time, how='numpy', delta_t=67.0, numthreads=4):
974974
975975
delta_t : float, optional, default 67.0
976976
Difference between terrestrial time and UT1.
977-
If delta_t is None, uses spa.calculate_deltat
977+
If delta_t is None, uses :py:func:`calculate_deltat`
978978
using time.year and time.month from pandas.DatetimeIndex.
979979
For most simulations the default delta_t is sufficient.
980980
*Note: delta_t = None will break code using nrel_numba,
@@ -1005,7 +1005,7 @@ def nrel_earthsun_distance(time, how='numpy', delta_t=67.0, numthreads=4):
10051005

10061006
spa = _spa_python_import(how)
10071007

1008-
delta_t = delta_t or spa.calculate_deltat(time.year, time.month)
1008+
delta_t = delta_t or calculate_deltat(time.year, time.month)
10091009

10101010
dist = spa.earthsun_distance(unixtime, delta_t, numthreads)
10111011

@@ -1476,3 +1476,148 @@ def sun_rise_set_transit_geometric(times, latitude, longitude, declination,
14761476
sunset = _local_times_from_hours_since_midnight(times, sunset_hour)
14771477
transit = _local_times_from_hours_since_midnight(times, transit_hour)
14781478
return sunrise, sunset, transit
1479+
1480+
1481+
def calculate_deltat(year, month):
1482+
"""Calculate the difference between Terrestrial Dynamical Time (TD)
1483+
and Universal Time (UT).
1484+
1485+
Note: This function is not yet compatible for calculations using
1486+
Numba.
1487+
1488+
Parameters
1489+
----------
1490+
year : numeric
1491+
Calendar year for which to calculate the time offset
1492+
month : numeric
1493+
Calendar month (1-12) for which to calculate the time offset
1494+
1495+
Returns
1496+
-------
1497+
deltat : numeric
1498+
1499+
References
1500+
----------
1501+
.. [1] `NASA GSFC: Polynomial Expressions for Delta T (ΔT)
1502+
<http://eclipse.gsfc.nasa.gov/SEcat5/deltatpoly.html>`_
1503+
"""
1504+
1505+
plw = 'Deltat is unknown for years before -1999 and after 3000. ' \
1506+
'Delta values will be calculated, but the calculations ' \
1507+
'are not intended to be used for these years.'
1508+
1509+
try:
1510+
if np.any((year > 3000) | (year < -1999)):
1511+
warnings.warn(plw)
1512+
except ValueError:
1513+
if (year > 3000) | (year < -1999):
1514+
warnings.warn(plw)
1515+
except TypeError:
1516+
return 0
1517+
1518+
y = year + (month - 0.5)/12
1519+
1520+
deltat = np.where(year < -500,
1521+
1522+
-20+32*((y-1820)/100)**2, 0)
1523+
1524+
deltat = np.where((-500 <= year) & (year < 500),
1525+
1526+
10583.6-1014.41*(y/100)
1527+
+ 33.78311*(y/100)**2
1528+
- 5.952053*(y/100)**3
1529+
- 0.1798452*(y/100)**4
1530+
+ 0.022174192*(y/100)**5
1531+
+ 0.0090316521*(y/100)**6, deltat)
1532+
1533+
deltat = np.where((500 <= year) & (year < 1600),
1534+
1535+
1574.2-556.01*((y-1000)/100)
1536+
+ 71.23472*((y-1000)/100)**2
1537+
+ 0.319781*((y-1000)/100)**3
1538+
- 0.8503463*((y-1000)/100)**4
1539+
- 0.005050998*((y-1000)/100)**5
1540+
+ 0.0083572073*((y-1000)/100)**6, deltat)
1541+
1542+
deltat = np.where((1600 <= year) & (year < 1700),
1543+
1544+
120-0.9808*(y-1600)
1545+
- 0.01532*(y-1600)**2
1546+
+ (y-1600)**3/7129, deltat)
1547+
1548+
deltat = np.where((1700 <= year) & (year < 1800),
1549+
1550+
8.83+0.1603*(y-1700)
1551+
- 0.0059285*(y-1700)**2
1552+
+ 0.00013336*(y-1700)**3
1553+
- (y-1700)**4/1174000, deltat)
1554+
1555+
deltat = np.where((1800 <= year) & (year < 1860),
1556+
1557+
13.72-0.332447*(y-1800)
1558+
+ 0.0068612*(y-1800)**2
1559+
+ 0.0041116*(y-1800)**3
1560+
- 0.00037436*(y-1800)**4
1561+
+ 0.0000121272*(y-1800)**5
1562+
- 0.0000001699*(y-1800)**6
1563+
+ 0.000000000875*(y-1800)**7, deltat)
1564+
1565+
deltat = np.where((1860 <= year) & (year < 1900),
1566+
1567+
7.62+0.5737*(y-1860)
1568+
- 0.251754*(y-1860)**2
1569+
+ 0.01680668*(y-1860)**3
1570+
- 0.0004473624*(y-1860)**4
1571+
+ (y-1860)**5/233174, deltat)
1572+
1573+
deltat = np.where((1900 <= year) & (year < 1920),
1574+
1575+
-2.79+1.494119*(y-1900)
1576+
- 0.0598939*(y-1900)**2
1577+
+ 0.0061966*(y-1900)**3
1578+
- 0.000197*(y-1900)**4, deltat)
1579+
1580+
deltat = np.where((1920 <= year) & (year < 1941),
1581+
1582+
21.20+0.84493*(y-1920)
1583+
- 0.076100*(y-1920)**2
1584+
+ 0.0020936*(y-1920)**3, deltat)
1585+
1586+
deltat = np.where((1941 <= year) & (year < 1961),
1587+
1588+
29.07+0.407*(y-1950)
1589+
- (y-1950)**2/233
1590+
+ (y-1950)**3/2547, deltat)
1591+
1592+
deltat = np.where((1961 <= year) & (year < 1986),
1593+
1594+
45.45+1.067*(y-1975)
1595+
- (y-1975)**2/260
1596+
- (y-1975)**3/718, deltat)
1597+
1598+
deltat = np.where((1986 <= year) & (year < 2005),
1599+
1600+
63.86+0.3345*(y-2000)
1601+
- 0.060374*(y-2000)**2
1602+
+ 0.0017275*(y-2000)**3
1603+
+ 0.000651814*(y-2000)**4
1604+
+ 0.00002373599*(y-2000)**5, deltat)
1605+
1606+
deltat = np.where((2005 <= year) & (year < 2050),
1607+
1608+
62.92+0.32217*(y-2000)
1609+
+ 0.005589*(y-2000)**2, deltat)
1610+
1611+
deltat = np.where((2050 <= year) & (year < 2150),
1612+
1613+
-20+32*((y-1820)/100)**2
1614+
- 0.5628*(2150-y), deltat)
1615+
1616+
deltat = np.where(year >= 2150,
1617+
1618+
-20+32*((y-1820)/100)**2, deltat)
1619+
1620+
deltat = deltat.item() if np.isscalar(year) & np.isscalar(month)\
1621+
else deltat
1622+
1623+
return deltat

‎pvlib/spa.py

Lines changed: 0 additions & 129 deletions
Original file line numberDiff line numberDiff line change
@@ -1246,132 +1246,3 @@ def earthsun_distance(unixtime, delta_t, numthreads):
12461246
return R
12471247

12481248

1249-
def calculate_deltat(year, month):
1250-
"""Calculate the difference between Terrestrial Dynamical Time (TD)
1251-
and Universal Time (UT).
1252-
1253-
Note: This function is not yet compatible for calculations using
1254-
Numba.
1255-
1256-
Equations taken from http://eclipse.gsfc.nasa.gov/SEcat5/deltatpoly.html
1257-
"""
1258-
1259-
plw = 'Deltat is unknown for years before -1999 and after 3000. ' \
1260-
'Delta values will be calculated, but the calculations ' \
1261-
'are not intended to be used for these years.'
1262-
1263-
try:
1264-
if np.any((year > 3000) | (year < -1999)):
1265-
warnings.warn(plw)
1266-
except ValueError:
1267-
if (year > 3000) | (year < -1999):
1268-
warnings.warn(plw)
1269-
except TypeError:
1270-
return 0
1271-
1272-
y = year + (month - 0.5)/12
1273-
1274-
deltat = np.where(year < -500,
1275-
1276-
-20+32*((y-1820)/100)**2, 0)
1277-
1278-
deltat = np.where((-500 <= year) & (year < 500),
1279-
1280-
10583.6-1014.41*(y/100)
1281-
+ 33.78311*(y/100)**2
1282-
- 5.952053*(y/100)**3
1283-
- 0.1798452*(y/100)**4
1284-
+ 0.022174192*(y/100)**5
1285-
+ 0.0090316521*(y/100)**6, deltat)
1286-
1287-
deltat = np.where((500 <= year) & (year < 1600),
1288-
1289-
1574.2-556.01*((y-1000)/100)
1290-
+ 71.23472*((y-1000)/100)**2
1291-
+ 0.319781*((y-1000)/100)**3
1292-
- 0.8503463*((y-1000)/100)**4
1293-
- 0.005050998*((y-1000)/100)**5
1294-
+ 0.0083572073*((y-1000)/100)**6, deltat)
1295-
1296-
deltat = np.where((1600 <= year) & (year < 1700),
1297-
1298-
120-0.9808*(y-1600)
1299-
- 0.01532*(y-1600)**2
1300-
+ (y-1600)**3/7129, deltat)
1301-
1302-
deltat = np.where((1700 <= year) & (year < 1800),
1303-
1304-
8.83+0.1603*(y-1700)
1305-
- 0.0059285*(y-1700)**2
1306-
+ 0.00013336*(y-1700)**3
1307-
- (y-1700)**4/1174000, deltat)
1308-
1309-
deltat = np.where((1800 <= year) & (year < 1860),
1310-
1311-
13.72-0.332447*(y-1800)
1312-
+ 0.0068612*(y-1800)**2
1313-
+ 0.0041116*(y-1800)**3
1314-
- 0.00037436*(y-1800)**4
1315-
+ 0.0000121272*(y-1800)**5
1316-
- 0.0000001699*(y-1800)**6
1317-
+ 0.000000000875*(y-1800)**7, deltat)
1318-
1319-
deltat = np.where((1860 <= year) & (year < 1900),
1320-
1321-
7.62+0.5737*(y-1860)
1322-
- 0.251754*(y-1860)**2
1323-
+ 0.01680668*(y-1860)**3
1324-
- 0.0004473624*(y-1860)**4
1325-
+ (y-1860)**5/233174, deltat)
1326-
1327-
deltat = np.where((1900 <= year) & (year < 1920),
1328-
1329-
-2.79+1.494119*(y-1900)
1330-
- 0.0598939*(y-1900)**2
1331-
+ 0.0061966*(y-1900)**3
1332-
- 0.000197*(y-1900)**4, deltat)
1333-
1334-
deltat = np.where((1920 <= year) & (year < 1941),
1335-
1336-
21.20+0.84493*(y-1920)
1337-
- 0.076100*(y-1920)**2
1338-
+ 0.0020936*(y-1920)**3, deltat)
1339-
1340-
deltat = np.where((1941 <= year) & (year < 1961),
1341-
1342-
29.07+0.407*(y-1950)
1343-
- (y-1950)**2/233
1344-
+ (y-1950)**3/2547, deltat)
1345-
1346-
deltat = np.where((1961 <= year) & (year < 1986),
1347-
1348-
45.45+1.067*(y-1975)
1349-
- (y-1975)**2/260
1350-
- (y-1975)**3/718, deltat)
1351-
1352-
deltat = np.where((1986 <= year) & (year < 2005),
1353-
1354-
63.86+0.3345*(y-2000)
1355-
- 0.060374*(y-2000)**2
1356-
+ 0.0017275*(y-2000)**3
1357-
+ 0.000651814*(y-2000)**4
1358-
+ 0.00002373599*(y-2000)**5, deltat)
1359-
1360-
deltat = np.where((2005 <= year) & (year < 2050),
1361-
1362-
62.92+0.32217*(y-2000)
1363-
+ 0.005589*(y-2000)**2, deltat)
1364-
1365-
deltat = np.where((2050 <= year) & (year < 2150),
1366-
1367-
-20+32*((y-1820)/100)**2
1368-
- 0.5628*(2150-y), deltat)
1369-
1370-
deltat = np.where(year >= 2150,
1371-
1372-
-20+32*((y-1820)/100)**2, deltat)
1373-
1374-
deltat = deltat.item() if np.isscalar(year) & np.isscalar(month)\
1375-
else deltat
1376-
1377-
return deltat

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