{"id":375,"date":"2023-08-02T15:39:19","date_gmt":"2023-08-02T15:39:19","guid":{"rendered":"https:\/\/itwg.ssec.wisc.edu\/rtsp\/?page_id=375"},"modified":"2023-08-03T17:54:32","modified_gmt":"2023-08-03T17:54:32","slug":"profile-utility-introduction","status":"publish","type":"page","link":"https:\/\/itwg.ssec.wisc.edu\/rtsp\/profile-utility-introduction\/","title":{"rendered":"Profile Utility Introduction"},"content":{"rendered":"\n

Units Conversion Module<\/h2>\n\n\n\n

The\u00a0Units_Conversion\u00a0module contains a number of functions for converting the units of atmospheric absorber concentrations. This type of conversion information is usually hard to dig up so this module is an attempt to gather as many of the conversions as possible in one place. All of the available conversion routines are shown in the table below. For more details on the available routines, click on the links below or see the\u00a0Units_Conversion<\/a>\u00a0module documentation.<\/p>\n\n\n\n

Specific amount <-> mixing ratio<\/th><\/tr>
SA_to_MR<\/td>Function to convert gas concentrations from specific amount to mixing ratio.<\/td><\/tr>
MR_to_SA<\/td>Function to convert gas concentrations from mixing ratio to specific amount<\/td><\/tr>
Relative humidity <-> mixing ratio<\/th><\/tr>
RH_to_MR<\/td>Function to convert water vapor amounts from relative humidity to mixing ratio.<\/td><\/tr>
MR_to_RH<\/td>Function to convert water vapor amounts from mixing ratio to relative humidity.<\/td><\/tr>
Mixing ratio <-> ppmv<\/th><\/tr>
MR_to_PPMV<\/td>Function to convert gas concentrations from mixing ratio to parts-per-million by volume.<\/td><\/tr>
PPMV_to_MR<\/td>Function to convert gas concentrations from parts-per-million by volume to mixing ratio.<\/td><\/tr>
Partial pressure <-> ppmv<\/th><\/tr>
PPMV_to_PP<\/td>Function to convert gas concentrations from parts-per-million by volume to partial pressure.<\/td><\/tr>
PP_to_PPMV<\/td>Function to convert gas concentrations from partial pressure to parts-per-million by volume.<\/td><\/tr>
Partial pressure <-> mixing ratio<\/th><\/tr>
MR_to_PP<\/td>Function to convert gas concentrations from mixing ratio to partial pressure in hectoPascals<\/td><\/tr>
PP_to_MR<\/td>Function to convert gas concentrations from partial pressure in hectoPascals to mixing ratio in g\/kg.<\/td><\/tr>
Partial pressure <-> mass density<\/th><\/tr>
PP_to_MD<\/td>Function to convert gas concentrations in pressure units to mass density.<\/td><\/tr>
MD_to_PP<\/td>Function to convert gas concentration mass density to partial pressure.<\/td><\/tr>
Partial pressure <-> number density<\/th><\/tr>
PP_to_ND<\/td>Function to convert gas concentrations from (partial) pressures in hectoPascals to molecules\/m^3.<\/td><\/tr>
ND_to_PP<\/td>Function to convert gas concentrations from number densities in molecules\/m^3 to (partial) pressures in hectoPascals.<\/td><\/tr>
Number density <-> ppmv<\/th><\/tr>
PPMV_to_ND<\/td>Function to convert gas concentrations from parts-per-million by volume to molecules\/m^3.<\/td><\/tr>
ND_to_PPMV<\/td>Function to convert gas concentrations from number densities in molecules\/m^3 to parts-per-million by volume.<\/td><\/tr>
Column density <-> ppmv<\/th><\/tr>
PPMV_to_KMOL<\/td>Function to convert gas concentrations from parts-per- million by volume to kilomoles per cm^2.<\/td><\/tr>
KMOL_to_PPMV<\/td>Function to convert gas concentrations from kilomoles per cm^2 to parts-per-million by volume.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Atmospheric Properties Module<\/h2>\n\n\n\n

This module contains a number of routines to compute various properties of the atmosphere.<\/p>\n\n\n\n

Molecular weight of air,\u00a0MW_Air<\/h3>\n\n\n\n

This function calculates the effective molecular weight of air. To calculate the air density accurately the profile of the effective molecular weight of air (MWair<\/sub><\/em>) is required. Although MWair<\/sub><\/em> does not change a great deal with altitude, the variation is significant as the ratios of concentrations of various absorbers change.<\/p>\n\n\n\n

The most significant contributor to the change in MWair<\/sub><\/em> is water vapor, mostly in the lower troposphere. The effect of the other absorbers (O3<\/sub>, CO2<\/sub>, etc.) can be considered negligible. To offset the displacement of “air molecules” by water vapor, the molecular weight of air is given by,<\/p>\n\n\n\n

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where<\/p>\n\n\n\n