Units Reference: for AC1
=============================
This document summarizes unit definitions relevant to the `amocarray` project, based on `udunits2-base.xml`.
Check out `udunits `_.
SI base units (XML) are `here `_.
Derived units (XML) are `here `_.
Non-SI units including sverdrup, **where apparently we cannot use Sv because it also means "sievert" in the SI unit-system**.
Variables
---------
Mass/Volume Units
~~~~~~~~~~~~~~~~~
+--------------------------+---------------+------------------+
| Name | Symbol | Definition |
+==========================+===============+==================+
| gram_per_cubic_meter | g/m³, | 0.001 kg/m³ |
| | g m-3 | |
+--------------------------+---------------+------------------+
| kilogram_per_cubic_meter | kg/m³, | base SI unit |
| | **kg m-3** | |
+--------------------------+---------------+------------------+
Length Units
~~~~~~~~~~~~~~~~~
+-----------+------------+----------------+
| Name | Symbol | Definition |
+===========+============+================+
| meter | **m** | base SI unit |
+-----------+------------+----------------+
| centimeter| cm | 0.01 m |
+-----------+------------+----------------+
| kilometer | km | 1000 m |
+-----------+------------+----------------+
Temperature Units
~~~~~~~~~~~~~~~~~
+------------------+---------------+-----------------------------+
| Name | Symbol | Definition |
+==================+===============+=============================+
| degree_Celsius | °C, | 1 K offset by -273.15 |
| | **Celsius** | |
+------------------+---------------+-----------------------------+
| kelvin | K | base SI unit |
+------------------+---------------+-----------------------------+
Conductivity Units
~~~~~~~~~~~~~~~~~
+-----------------------------+-----------+-------------------+
| Name | Symbol | Definition |
+=============================+===========+===================+
| siemens_per_meter | S/m, | base SI unit |
| | **S m-1** | |
+-----------------------------+-----------+-------------------+
| millisiemens_per_centimeter | mS/cm | 0.1 S/m |
+-----------------------------+-----------+-------------------+
Pressure Units
~~~~~~~~~~~~~~~~~
+------------+------------+----------------------+
| Name | Symbol | Definition |
+============+============+======================+
| decibar | **dbar** | 10,000 Pa |
+------------+------------+----------------------+
| kilopascal | kPa | 1,000 Pa |
+------------+------------+----------------------+
| pascal | Pa | base SI pressure |
+------------+------------+----------------------+
| bar | bar | 100,000 Pa |
+------------+------------+----------------------+
Velocity Units
~~~~~~~~~~~~~~~~~
+------------------------+-----------+----------------+
| Name | Symbol | Definition |
+========================+===========+================+
| centimeter_per_second | cm/s, | 0.01 m/s |
| | cm s-1 | |
+------------------------+-----------+----------------+
| meter_per_second | m/s, | base SI unit |
| | **m s-1** | |
+------------------------+-----------+----------------+
Angle Units (Accepted Non-SI)
~~~~~~~~~~~~~~~~~
These units are accepted for use with SI and commonly used in geophysical data.
+-------------+-------------+--------------------------+
| Name | Symbol | Conversion to radians |
+=============+=============+==========================+
| degree | °, | π / 180 |
| | **degrees** | |
+-------------+-------------+--------------------------+
| arcminute | ′ | (1/60) degree |
+-------------+-------------+--------------------------+
| arcsecond | ″ | (1/60) arcminute |
+-------------+-------------+--------------------------+
Notes:
- Degrees are commonly used for geographic coordinates (latitude and longitude).
- These are dimensionless units in the SI sense but critical for interpreting spatial data.
Transport Units
~~~~~~~~~~~~~~~~~
+-------------------------+------------+-----------------------------+
| Name | Symbol | Definition |
+=========================+============+=============================+
| sverdrup, | Sv* | 1e6 m³/s |
| **Sverdrup** | | alias for Sv |
+-------------------------+------------+-----------------------------+
| cubic_meter_per_second | m³/s, | Ocean volume transport |
| | **m3 s-1** | |
+-------------------------+------------+-----------------------------+
***Not** recommended since it conflicts with SI "sievert".
Energy and Power Units
~~~~~~~~~~~~~~~~~
+-----------+--------+--------------------------+
| Name | Symbol | Definition |
+===========+========+==========================+
| watt | W | J/s = kg·m²/s³ |
+-----------+--------+--------------------------+
| kilowatt | kW | 1000 W |
+-----------+--------+--------------------------+
| megawatt | MW | 1e6 W |
+-----------+--------+--------------------------+
| petawatt | **PW** | 1e15 W |
+-----------+--------+--------------------------+
| joule | J | N·m = kg·m²/s² |
+-----------+--------+--------------------------+
+--------------+--------+-------------------------+
| Name | Symbol | Definition |
+==============+========+=========================+
| kilojoule | kJ | 1000 J |
+--------------+--------+-------------------------+
| gigajoule | GJ | 1e9 J |
+--------------+--------+-------------------------+
Surface Heat Flux Units
~~~~~~~~~~~~~~~~~
+--------------------------+------------+------------------------------+
| Name | Symbol | Definition |
+==========================+============+==============================+
| watt_per_square_meter | W/m², | Heat flux density |
| | **W m-2** | |
+--------------------------+------------+------------------------------+
Mapping of Custom Conversions
-----------------------------
+------------------+------------------+------------------+--------------------------+
| Original Unit | Canonical Unit | Factor | Notes |
+==================+==================+==================+==========================+
| cm/s, cm s-1 | m s-1 | 0.01 | Velocity |
+------------------+------------------+------------------+--------------------------+
| S/m | mS cm-1 | 0.1 | Conductivity |
+------------------+------------------+------------------+--------------------------+
| dbar | Pa, kPa | 10000, 10 | Pressure |
+------------------+------------------+------------------+--------------------------+
| degrees_Celsius | Celsius | 1 | Temperature |
+------------------+------------------+------------------+--------------------------+
| m | cm, km | 100, 0.001 | Length |
+------------------+------------------+------------------+--------------------------+
| g m-3 | kg m-3 | 0.001 | Density |
+------------------+------------------+------------------+--------------------------+
| Sverdrup | Sv* | 1 | Transport |
+------------------+------------------+------------------+--------------------------+
| W, J | watt, joule | base units | Energy and Power |
+------------------+------------------+------------------+--------------------------+
***Not** recommended since it conflicts with SI "sievert".
SI Unit Prefixes
------------------
Standard prefixes supported by UDUNITS-2 for scaling base and derived units.
+-----------+---------+--------------+
| Prefix | Symbol | Factor |
+===========+=========+==============+
| yotta | Y | 1e24 |
| zetta | Z | 1e21 |
| exa | E | 1e18 |
| peta | P | 1e15 |
| tera | T | 1e12 |
| giga | G | 1e9 |
| mega | M | 1e6 |
| kilo | k | 1e3 |
| hecto | h | 1e2 |
| deca | da | 1e1 |
| deci | d | 1e-1 |
| centi | c | 1e-2 |
| milli | m | 1e-3 |
| micro | µ (u) | 1e-6 |
| nano | n | 1e-9 |
| pico | p | 1e-12 |
| femto | f | 1e-15 |
| atto | a | 1e-18 |
| zepto | z | 1e-21 |
| yocto | y | 1e-24 |
+-----------+---------+--------------+
Notes:
- Prefixes can be applied to compatible base/derived units (e.g., kW, cm, µS/cm).
- `µ` is often typed as `u` in ASCII-only environments.