Common Unit Conversions
For many transformations, particularly when automated, please use the udunits2 software where possible. For example, in R, you can use
library(udunits2)
## transform meters to mm
ud.convert(10, "m", "mm")
## equivalently, via the udunits synonym database
ud.convert(10, "meters", "millimeters")
## it can also handle more complex units
ud.convert(10, "m/s", "mm/d")
NB: Many of these conversions have been automated within PEcAn.
Useful conversions for entering site, management, yield, and trait data \label{tab:conversions}
From ((X))
to ((Y))
Conversion
Notes
(X_2=)root production
(X_1=)root biomass & root turnover rate
(Y = X_2/X_1)
Gill [2000]
DD(^{\circ}) MM'SS
XX.ZZZZ
(\textrm{XX.ZZZZ} = \textrm{XX} + \textrm{MM}/60+\textrm{SS}/60)
to convert latitude or longitude from degrees, minutes, seconds to decimal degrees
lb
kg
(Y=X\times 2.2)
mm/s
(\mu) mol CO(_2) m(^{2}) s(^{-1})
(Y=X\times 0.04)
m(^2)
ha
(Y = X/10^6)
g/m(^2)
kg/ha
(Y=X\times 10)
US ton/acre
Mg/ha
(Y = X\times 2.24)
m(^3)/ha
cm
(Y=X/100)
units used for irrigation and rainfall
% roots
root:shoot (q)
(Y=\frac{X}{1-X})
(\% \text{roots} = \frac{\text{root biomass}}{\text{total biomass}})
(\mu) mol cm(^{-2}) s(^{-1})
mmol m(^{-2}) s(^{-1})
(Y = X/10)
mol m(^{-2}) s(^{-1})
mmol m(^{-2}) s(^{-1})
(Y = X/10^6)
mol m(^{-2}) s(^{-1})
(\mu) mol cm(^{-2}) s(^{-1})
(Y = X/ 10^5)
mm s(^{-2})
mmol m(^{-3}) s(^{-1})
(Y=X/41)
Korner et al. [1988]
mg CO(_2) g(^{-1}) h(^{-1})
(\mu) mol kg(^{-1}) s(^{-1})
(Y = X\times 6.31)
used for root_respiration_rate
(\mu) mol
mol
(Y= X\times 10^6)
julian day (1--365)
date
see ref: http://disc.gsfc.nasa.gov/julian_calendar.shtml (NASA Julian Calendar)
spacing (m)
density (plants m(^{2}))
(Y=\frac{1}{\textrm{row spacing}\times\textrm{plant spacing}})
kg ha(^{-1}) y(^{-1})
Mg ha(^{-1}) y(^{-1})
(Y= X/1000)
g m(^{-2}) y(^{-1})
Mg ha(^{-1}) y(^{-1})
(Y= X/100)
kg
mg
(Y=X\times 10^6)
cm(^2)
m(^2)
(Y=X\times 10^4)
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