# et0: FAO Penman-Monteith evapotranspiration equation In sirad: Functions for Calculating Daily Solar Radiation and Evapotranspiration

## Description

'et0' estimates evapotranspiration based on FAO Penman-Monteith equation

## Usage

 `1` ```et0(Tmax,Tmin, vap_pres,sol_rad,tal,z,uz,meah=10,extraT=NA,days=NA,lat=NA) ```

## Arguments

 `Tmax` Vector of length n containing daily maximum temperature [C]. `Tmin` Vector of length n containing daily minumum temperature [C]. `vap_pres` Vector of length n of mean daily vapour pressure [kPa]. `sol_rad` Vector of length n of daily solar radiation [MJm-2d-1]. `tal` Clear sky transmissivity [0-1]. `z` Altitude above the sea level [m]. `uz` Wind speed measured at heith 'meah' [ms-1]. `meah` The height (above the ground level) of the wind speed measurement [m]. `extraT` Optional. Vector of length n of extraterrestrial solar radiation [MJm-2d-1]. If 'NA' then it is calculated by the function. Providing extraterrestrial solar radiation speeds up the computation. `days` Required only if extraT=NA. Vector of class 'Date' of length n. `lat` Required only if extraT=NA. Latitude in decimal degrees.

## Value

Vector of length n of daily reference evapotranspiration. [mmd-1]

## Author(s)

Jedrzej S. Bojanowski

## References

Allen, R.G., L.S. Pereira, D. Raes, and M. Smith. 1998. Crop Evapotranspiration: Guidelines for computing crop water requirements. Irrigation and Drainage Paper 56, Food and Agriculture Organization of the United Nations, Rome, pp. 300.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14``` ```data(Metdata) tmax <- Metdata\$meteo\$TEMP_MAX tmin <- Metdata\$meteo\$TEMP_MIN vpres <- Metdata\$meteo\$VAP_PRES days <- Metdata\$meteo\$DAY lat <- Metdata\$LATITUDE rad_mea <- Metdata\$meteo\$RAD_MEA z <- Metdata\$ALTITUDE wind <- Metdata\$meteo\$WIND_10 tal <- cst(rad_mea,dayOfYear(Metdata\$meteo\$DAY),radians(Metdata\$LATITUDE)) et0(Tmax=tmax,Tmin=tmin, vap_pres=vpres,sol_rad=rad_mea,tal=tal,z=Metdata\$ALTITUDE, uz=wind,meah=10,extraT=NA,days=days,lat=lat) ```

### Example output

```  [1]  0.093584039  0.758724065  0.229489021  0.715499137  0.436485588
[6]  0.501881088  0.473089093  1.986900344  0.678340399  0.448545382
[11]  0.775637393  0.610724177  0.383732183  0.216833092  0.589215891
[16]  0.290104558  0.591256703  1.048488041  0.419515871  0.577133431
[21]  0.522369529  0.439285964  0.150448016  0.151788839  0.246063991
[26]  0.067712395  0.015629297  0.868592500  0.301138152  0.108985026
[31]  0.332742357  0.840260817  0.522328819  0.544833600  0.481216268
[36]  0.091929333  0.253870412  0.685132317  0.696798876  0.822293238
[41]  0.626430168  0.585493399  0.551899451  0.206876773  0.467978587
[46]  0.270109979  0.642829208  0.682936429  0.232472110  0.347355365
[51]  0.421662627  1.503364222  0.930380400  0.666931133  0.218138784
[56]  0.472132588  0.815660774  0.567932176  0.968717509  0.626201341
[61]  0.616629142  0.913666139  0.950749355  0.834068994  0.806999982
[66]  0.764443088  0.696984636  1.007618925  0.572023082  0.745579807
[71]  0.657118176  1.337831775  1.373693680  1.588169572  2.562157476
[76]  1.190605027  1.589288090  0.607843983  0.681294816  0.539630040
[81]  1.354347621  1.562026435  1.853841901  1.793226952  2.328568673
[86]  2.760060753  3.376586887  3.592716883  1.887869754  2.098346647
[91]  1.771112920  1.551804988  2.007074178  0.971508695  2.695743709
[96]  2.546834152  0.870704685  1.122458730  2.980806238  2.795634222
[101]  2.919977787  1.960957952  3.074582851  2.872287650  2.680360202
[106]  1.696869735  2.727906793  3.018337159  3.014521756  2.971302093
[111]  0.922057260  3.288793400  1.837087655  2.287902545  1.994198904
[116]  3.047065756  2.290312886  2.149575516  2.850705395  2.584083880
[121]  1.727693345  2.021708643  2.036614313  2.120536881  2.332231049
[126]  2.729046530  2.888046543  3.035099163  2.238869767  2.880484348
[131]  3.192457561  3.571302789  2.276134883  2.924667114  4.055366056
[136]  3.305900157  3.358626970  2.857027413  5.387403221  4.865213793
[141]  6.923361875  4.540243650  2.639800087  2.310955117  2.304916297
[146]  0.929946206  3.307931356  1.738528491  2.386523517  3.327830727
[151]  4.292008341  4.100575150  3.599175941  3.527269058  2.647723210
[156]  2.964914332  2.642478850  4.473506545  4.924348977  3.310754068
[161]  2.380631596  4.853378569  5.066804112  5.561126809  5.606425217
[166]  4.874597803  5.325160789  4.381830488  3.281906869  4.300739193
[171]  4.487123021  4.728635116  5.083305198  3.136831707  4.138826531
[176]  2.696871910  6.346840712  2.065768074  3.340815362  3.875749517
[181]  5.267626552  5.837396111  5.642411972  6.117259405  4.358454237
[186]  3.327351517  4.259418481  3.334235046  2.352252009  2.518281817
[191]  2.973052166  3.128968558  0.593265906  3.558592046  2.177514142
[196]  3.115322810  3.373963110  3.142418342  2.608458309  3.931798165
[201]  2.938560812  2.253376680  2.861164359  1.945830318  2.924322984
[206]  3.407297268  1.455075370  2.725298667  2.844440795  2.051177835
[211]  2.436476078  1.573182211  1.302928112  2.319168938  2.658963939
[216]  1.786901348  3.361615146  2.190419025  2.154321003  3.936806310
[221]  4.521852252  2.717138262  3.299380632  4.056995482  2.053931899
[226]  3.164223889  2.019579358  2.468236341  2.084842989  3.630671691
[231]  3.359470292  4.284266571  2.561223587  2.820394538  3.535147354
[236]  3.598458418  3.281973494  3.468099251  1.452761713  2.986050652
[241]  1.379667475  2.460559201  2.436091318  1.879307151  1.901321597
[246]  2.091058537  0.919975287  1.239627692  2.328969442  2.008568227
[251]  1.924313612  2.299342260  1.768986560  1.849420847  1.412248432
[256]  1.120373689  1.466694128  1.086667647  1.629568919  1.126638632
[261]  1.478789780  1.179110343  1.381859735  1.280771235  1.459735075
[266]  1.512651126  1.476317456  1.037047381  1.255992542  1.752329646
[271]  1.781016024  1.576142433  0.788781926  1.230232335  1.121014836
[276]  0.819279061  0.870721412  1.419774259  0.925268422  0.569534987
[281]  0.867752738  0.347255059 -0.086186362  0.909009010  0.948955829
[286]  1.185563654  1.017926691  1.031621974  1.146288307  0.904685823
[291]  0.398288502  0.782549829  0.966997292  0.807994680  0.821354221
[296]  0.672500813  0.542417600  0.637502439  0.302962847  0.877445762
[301]  0.408580372  0.557694593  1.101047237  0.484145139  0.175341494
[306]  0.264890506  0.220685809  0.493222677  0.119589770  0.204378460
[311]  0.195645344  0.461623795  0.148263861  0.383023393  0.412017123
[316]  0.193063133  0.095392850  0.127747432  0.258839273  0.347215553
[321]  0.146629393  0.119126179  0.210544098  0.137679994  0.143221447
[326]  0.129107006 -0.019552915 -0.321432030  0.512647807  0.098906654
[331]  0.657461241  0.698212638  0.034616555  0.095414650  0.113145304
[336]  0.444247045 -0.134498825  0.210929268  0.070852524  0.641654700
[341]  0.149847152  0.108269926  0.256770409  0.322341260  0.141198338
[346]  0.311821113  0.208732953  0.234446767  0.056130925  0.127286552
[351]  0.327580596  0.356294801  0.358836668  0.262268918  0.104593661
[356]  0.165991896  0.426356957  0.017580170  0.103732132  0.214853797
[361]  0.195636834  0.174086208  0.290729617  0.224628819  0.141278397
[366]  0.220999032  0.586122055  0.389288034  0.398770017  0.423933804
[371]  0.164457712  0.484822357  0.186808335 -0.007793673  0.161623498
[376]  0.289107358  0.367866442  0.482119291  0.351831537  0.456428507
[381]  0.305504291  0.471786169  0.532608193  0.488212530  0.752991016
[386]  0.561266485  0.483639834  0.275365626  0.299190417  0.459175613
[391]  0.498901884  0.299992981  0.415728918  0.551424615  0.785786942
[396]  0.315088117  0.785243797  0.578746948  0.957742624  0.782692966
[401]  0.457532714  0.296580833  0.243464551  0.393059738  0.268129388
[406]  0.558127035  0.427928916  0.749879590  0.880630004  0.858973597
[411]  0.673352408  0.889328790  0.873310100  0.786337002  0.762982730
[416]  0.480267045  0.723939640  0.715375909  0.966284881  0.870262876
[421]  1.461030720  1.243173702  1.253750141  1.079226462  1.677948599
[426]  0.753740097  0.451317047  1.107469519  1.957310968  1.186543825
[431]  0.446773727  1.220426272  0.839487708  0.754693723  1.455459384
[436]  1.419173833  1.621301299  1.082690982  2.129972512  1.465425544
[441]  1.168547200  1.754915714  1.512319883  0.953178327  1.480451023
[446]  1.899572904  2.419028689  2.494665136  2.297644219  2.148133639
[451]  2.152292331  1.873700852  1.726491488  1.585747043  1.250050448
[456]  2.405014291  2.253926949  1.719557113  1.587016762  2.999879265
[461]  3.129681694  4.679501262  4.168011755  4.499744189  3.782518731
[466]  4.025624922  4.738630127  4.834974557  5.024335897  5.190967373
[471]  4.304244089  3.254696639  3.180379872  2.690573916  1.291072208
[476]  2.102472392  2.162041445  1.578977517  1.461988173  2.167195238
[481]  2.486500103  2.397295841  2.211484264  3.294247029  2.926456370
[486]  1.636577964  2.036559502  3.244923630  2.861763334  3.679926206
[491]  3.110829237  3.771233715  3.670416668  4.683669121  4.701231139
[496]  4.753789738  6.109876437  6.403610652  6.294159792  3.869625015
[501]  3.200336523  2.370947574  2.493361654  4.218022121  4.342628766
[506]  1.913344232  4.257112718  3.623619596  4.499772753  2.647186265
[511]  2.186561668  3.531241268  3.852696645  4.781125863  4.803302225
[516]  6.093254008  5.993257816  6.284922603  6.152015115  5.445217197
[521]  5.561214311  3.214984280  3.327856659  4.393885564  3.397764929
[526]  4.594771945  5.604271688  5.000517454  5.420483496  5.384553050
[531]  5.856362572  6.051525646  5.584195848  4.325358155  5.533557818
[536]  5.125184465  4.197372637  5.272206801  5.583257972  5.644110380
[541]  5.206283622  3.492422077  3.220819201  3.523865423  3.909498258
[546]  4.360889890  3.411375900  2.918578402  4.235680559  4.749313033
[551]  5.335510550  4.461978458  3.958722932  3.003028258  2.758719948
[556]  2.974551332  2.246579336  1.737705670  1.191199506  1.908330652
[561]  3.325526986  2.857923349  2.053304133  3.510957218  2.783223886
[566]  2.605567598  2.561853992  2.988615262  2.248587421  2.628418423
[571]  2.640963205  2.125477313  1.816063938  2.771078371  2.594208597
[576]  1.295549742  2.901027939  1.719512918  2.987102255  3.024419376
[581]  2.760845832  3.079608103  1.876301214  1.817802173  3.238718500
[586]  3.225975504  3.048040023  3.154577041  3.158654466  2.568703133
[591]  2.473643278  1.748162537  1.749344817  2.369537888  2.863519247
[596]  3.236190670  2.780212746  2.614072599  2.330686510  1.247898237
[601]  1.682857884  1.554396757  1.709361055  1.825401685  1.218430203
[606]  1.427044671  1.259833467  1.704786459  1.203111584  0.927190743
[611]  1.171198378  0.977695580  1.329620385  0.888698629  0.696626402
[616]  0.924609756  0.963774880  0.943207001  1.205679669  0.686791176
[621]  0.826253997  0.555324483  1.101847344  1.139006191  0.683820823
[626]  0.810196871  1.234695681  2.143271405  0.474236507  1.100856683
[631]  0.353974373  1.158524707  1.275727310  0.752147002  0.583999267
[636]  0.385120567  0.673757503  0.820983988  1.066351287  0.411158890
[641]  0.881307211  0.735386239  0.923557183  0.722666431  0.772133698
[646]  0.624334066  0.420663237  0.793811552  0.742336537  0.775134428
[651]  0.366297266  0.263020890  0.570961552  0.412774273  0.520984917
[656]  1.092365985  0.921833900  0.389397298  0.231335064  0.623767805
[661]  0.370783718  0.420770785  0.684663186  0.472492067  0.833074890
[666]  0.697590631  1.198346623  0.722263780  0.751862632  0.592842197
[671]  0.452567747  0.369457215  0.471451218  0.966643789  1.219609922
[676]  0.432809559  0.272726439  0.229512797  0.595417073  0.572714662
[681]  0.485972506  0.218094822  0.450629720  0.375838758  0.542408784
[686]  0.262467977  0.176265245  0.884987766  0.569199415
```

sirad documentation built on May 1, 2019, 7:42 p.m.