4 •
••
• Document code: SS1-UM-1.05
Menus and Screens ..................................................................................30
More Psion and file handling notes.........................................................33
Navigating Psion directories and screens...............................................33
The Workabout User Guide........................................................................33
Navigating the Psion directories and screens.............................................33
Psion subdirectory usage in file select dialogs ...........................................34
Re-installing the SunData application icon..................................................35
Deleting unwanted Workabout files ............................................................35
Flashcards - reformatting............................................................................35
Data memory management.......................................................................36
Configuration and data file handling........................................................36
SunData Configuration files ........................................................................36
Data files.....................................................................................................37
Displaying data files on your PC..............................................................38
The .PRN file...............................................................................................38
The .CSV file...............................................................................................38
Data file layouts and data groups ...............................................................39
Measurement options...............................................................................41
Experiment design.....................................................................................41
Above-canopy reference requirements.......................................................41
Canopy type and BFS practicalities............................................................42
Canopy type and LAI estimates..................................................................42
Canopy Sampling volume...........................................................................42
Preferred light and weather conditions .......................................................43
Planning for the sun’s position....................................................................43
Advice on Absorption and ELADP values ...............................................44
Absorption...................................................................................................44
ELADP ........................................................................................................44
Relationship between Mean Leaf Angle and ELADP..................................45
SunScan System Measurement modes....................................................46
Workabout setup.........................................................................................46
The Autolog function...................................................................................47
Measurement procedures in the field.......................................................48
Probe handling in the field...........................................................................48
BFS handling in the field.............................................................................49
PAR calibrations .........................................................................................51
Environmental and moisture protection ......................................................53
LAI theory...................................................................................................54
Ingredients of the LAI computation method............................................54
Derivation of Wood’s SunScan canopy analysis equations...................55
The major assumptions...............................................................................55
Beer's law for canopy absorption................................................................56
Campbell's Ellipsoidal LAD equations.........................................................56
Transmission of Diffuse Light......................................................................56
Modelling the canopy transmission.............................................................58
Accuracy of LAI calculations.......................................................................60
Functions used to model canopy transmission......................................60
Diffuse light - cosine response sensor........................................................60
Diffuse light - hemispherical response sensor............................................60
Modelling incomplete PAR absorption and scattering.................................61
Calculating zenith angles............................................................................62
Summary.....................................................................................................62
Scientific references..................................................................................62
Technical Reference section....................................................................64