Units
==================================

OpenWQ's internal units generally follow the `IS <https://en.wikipedia.org/wiki/International_System_of_Units>`_ convention, except for mass. Instead of length (:math:`L`) we specify volume (:math:`L^3`) because it makes more sense when dealing with dissolved solutes in water.

* ``Mass`` (:math:`M`): gram (not IS unit to avoid very small numbers generally associated with concentrations in the environment)
* ``Volume`` (:math:`L^3`): cubic meter (using basic IS unit for length (meter))
* ``Time`` (:math:`T`): second (IS unit)

Different units may be used in the input and output files. They just need to specified in the respective json keys or values.
Below is a list of all the units permitted in OpenWQ together with the respective flags.

Mass (:math:`L`)
~~~~~~~~~~~~~~~~~~~~~~
* gigatonne (flag: ``GT``)
* negatonne (flag: ``MT``)
* tonne (flag: ``T``)
* tonne US (flag: ``TON_US``)
* tonne UK (flag: ``TON_UK``)
* kilogram (flag: ``KG``)
* gram (flag: ``G``)
* miligram (flag: ``MG``)
* micro gram  (flag: ``UG``)
* nano gram (flag: ``NG``)
* pico gram (flag: ``PG``)
* pound (flag: ``LB``)
* ounce (flag: ``OZ``)

Volume (:math:`L^3`)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* cubic kilometer (flag: ``KM3``)
* cubic meter (flag: ``M3``)
* cubic centimeter (flag: ``CM3``)
* cubic millimeter (flag: ``MM3``)
* liter (flag: ``L``)
* milliliter (flag: ``ML``)
* gallon (US) (flag: ``GAL_US``)
* quart (US) (flag: ``QT_US``)
* cubic mile (flag: ``MI3``)
* gigatonne (flag: ``GT``)
* cubic yard (flag: ``YD3``)
* cubic foot (flag: ``FT3``)
* cubic inch (flag: ``IN3``)
* cubic decimeter (flag: ``DM3``)
* exaliter (flag: ``EL``)
* petaliter (flag: ``PL``)
* teraliter (flag: ``TL``)
* gigaliter (flag: ``GL``)
* megaliter (flag: ``MEGL``)
* kiloliter (flag: ``KL``)
* hectoliter (flag: ``HL``)
* dekaliter (flag: ``AL``)
* deciliter (flag: ``DL``)
* centiliter (flag: ``CL``)
* microliter (flag: ``UL``)
* nanoliter (flag: ``NL``)
* picoliter (flag: ``PL``)
* barrel (US) (flag: ``BBL_US``)
* barrel (UK) (flag: ``BBL``)
* gallon (UK) (flag: ``GAL_UK``)
* quart (UK) (flag: ``QT_UK``)
* pint (UK) (flag: ``PT_UK``)
* fluid ounce (US) (flag: ``FL_OZ_US``)
* fluid ounce (UK) (flag: ``FL_OZ_UK``)
* acre-foot [ac*ft] (flag: ``AC_FT``)
* acre-foot (US survey) (flag: ``AC_FT_US``)
* acre-inch [ac*in] (flag: ``AC_IN``)

Time (:math:`T`)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* second (flag: ``SEC``)
* minute (flag: ``MIN``)
* hour (flag: ``HOUR``)
* day (flag: ``DAY``)
* week (flag: ``WEEK``)
* month (flag: ``MONTH``)
* year (flag: ``YEAR``)