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This appendix provides short descriptions, and supporting links (when available) for data parameters in Giovanni-3 instances. The supporting links may be external sources not specifically related to, or endorsed by, NASA earth science research.
Absorption coefficient
The absorption and backscattering coefficients are inherent optical properties (IOP) of a medium. Absorption refers to the amount of light energy absorbed over a unit distance by the particulates of the medium. The SeaWifs provides absorption coefficient for seawater, phytoplankton, and the combined coefficient for dissolved and detrital particulate matter (acdm) at 443 nm .
Aerosol Index (or UV Aerosol Index)
The UV aerosol index also called Absorbing Aerosol index is a qualitative indicator of near-UV absorbing aerosol particles such as smoke or mineral dust (no indication of sulfate Aerosols). OMI provides UV aerosol index. See also Aerosol Absorption Optical Depth(a quantitative measure of near UV absorbing aerosol particles)
Aerosol Optical Depth or Thickness or Aerosol Extinction
A measure of radiation extinction at the encounter of aerosol particles in the atmosphere.
The extinction or total aerosol optical depth is measure of radiation extinction due to aerosol scattering and absorption. It is volume extinction coefficient times the layer thickness. Aerosol Total Optical Thickness are available through Giovanni at 550 nm from the MODIS; at 865 and 869 nm from the SeaWiFs; and at number of wavelengths between 342 and 500 nm from Aura/OMI. OMI also provides Aerosol Absorption Optical Depth for Near-UV wavelengths.
Aerosol Absorption Optical Depth (near-UV)
The aerosol absorption optical depth is measure of concentration of near-UV absorbing aerosol particles such as smoke and mineral dust. OMI products provide Near-UV Aerosol Absorption Optical Depth at at number of wavelengths between 342 and 500 nm .
Aerosol Single Scattering Albedo
single scattering albedo is the ratio of scattering optical depth to the total optical depth (scattering + extinction) of the atmosphere.
Aerosol Small Mode Fraction
Also known as aerosol fine mode fraction, it is the ratio of small mode optical depth (thickness) to the total AOD. MODIS provides Aerosol fine mode fraction at 550 nm. In Giovanni the averaged area plots and time-series utilize optical depth based weighting.
Aerosol Mass Concentration (QA-weighted)
MODIS provides columnar aerosol mass concentration over land, and over ocean
Aerosol Angstrom Exponent or Angstrom Coefficient
It is a mesure of spectral dpendence of Aerosol optical depth. MODIS atmospheric science team provides Angstrom exponent for the aerosols over Land based on 470 and 660 nm optical depths(QA-weighted)
Ocean team (as part of atmospheric correction algorithm) provides Angstrom coefficient based on aerosol optical depth values between 510-865 nm for SeaWiFS, and bbetween 531-869 nm for MODIS-Aqua(QA-weighted).
Aerosol Fine Particulate Matter - PM2.5
PM2.5 is the concentration (in micrograms per cubic meter) of aerosol particles suspended in the atmosphere with a diameter of 2.5 micrometers (µm) or less. The data are from the U.S Environmental Protection Agency (EPA) AIRNow (http://airnow.gov) real time concentrations over the continental U.S. The values shown are the average of the hourly concentrations between 15 Z and 22 Z in order to maximize collocation with the MODIS Terra and Aqua Aerosol Optical Depth (AOD) overpass times over the U.S. Giovanni gridded PM2.5 concentrations are currently only available over the continental U.S.
Aerosol Effective Radius
Aerosol radiative effect are strongly dependent on aerosol particle radius and particle optical characteristics. MODIS provides effective radius (QA-weighted) of aerosols over the ocean for 0.55 microns light scattering.
Aerosol Scattering Angle
The angle between the initial and final paths traveled by a scattered particle or photon.
Fire Pixel Count
This product presents the total number of fire pixels observed in each grid cell. “Overpass Corrected Fire Pixel Count” presents the total number of pixels corrected for multiple satellite overpasses and missing observations. “Cloud and Overpass Corrected Fire Pixel Count” presents number of pixels corrected for multiple satellite overpasses, missing observations, and variable cloud cover.
Fire Radiative Power
The fire radiative power, measured in MW, is the brightness temperature of fire pixels at 4 µm. See page 12 in MODIS Fire Products for the method of calculation.
Epsilon of aerosol correction (Eps_78)
The epsilon is an index describing the two candidate models selected by the atmospheric correction algorithm for ocean color data Level 2 algorithms
Normalized water-leaving radiance (nLw)
Normalized water-leaving radiance is the water-leaving radiance determined at the satellite divided by the cosine of the sun angle and the atmospheric diffuse transmittance. Normalized water-leaving radiance is the fundamental variable that allows determination of oceanic geophysical parameters using remotely-sensed radiances.
Clear-Sky Outgoing Longwave Radiation Flux
The outgoing longwave (IR) radiation intensity under clear sky conditions. Units are Watts per square meter. This is the amount of energy being radiated from the Earth at IR wavelength
Erythemally Weighted Daily Dose
Daily dose is the diurnally integrated amount of harmful UV radiation on the Earth's surface. The daily dose of the UV Record service, that is given in kJ per squre meter units, is an estimate of the erythemally weighted daily dose taking into account the attenuating effect of clouds. Additionally, the estimate is corrected for strongly absorbing aerosols in the clear-sky case
Local Noon Erythemal UV Irradiance
This quantity is a a measure of the potential for biological damage due to solar UV radiation. Erythemal exposure is calculated using UV irradiance reaching the surface of earth and weighted by model values of the susceptibilty of Caucasian skin to sunburn(erythema). As indicated by the name, this quantity is determined for local noon solar angles.
Surface Reflectivity
Surface reflectivity (also known as reflectance) is the ratio of the amount of radiation reflected from a surface to the amount of incident radiation on the surface. When expressed in terms of the total amount of radiation incident on a surface (not the amount of radiation at a specific wavelength or wavelength band) this quantity can also be called albedo.
Cloud Reflectivity
Reflectivity, also known as reflectance, is (the ratio of the radiant energy reflected by a body to the energy incident on it. Cloud reflectivity is a measure of the energy reflected by atmospheric clouds.
Cirrus Cloud Reflectance (QA-weighted)
Reflectance (the ratio of the radiant energy reflected by a body to the energy incident on it) of cirrus clouds in the atmosphere. Cirrus clouds are thin filamentous
clouds (usually composed of fine ice crystals) which occur at high altitude
Cloud Condensation Nuclei over Ocean (QA-weighted)
Number of cloud condensation nuclei (CCN) in the column at 0.55 microns for best solution. Cloud condensatiion nuclei are
are small aerosol particles (approximately 0.0002 mm) which provide surface area enhancing formation of cloud droplets
Cloud Effective Radius Combined (QA-weighted)
Combined Effective particle radius
Cloud Effective Radius Ice Phase (QA-weighted)
Effective particle radius for ice clouds
Cloud Effective Radius Liquid Phase (QA-weighted)
Effective particle radius for liquid water clouds
Cloud Fraction (Radiative)
The radiative cloud fraction is an effective cloud fraction. It characterizes the fraction of the incoming radiation that is scattered by clouds.
Cloud Fraction (Day and Night)
MODIS: Cloud Fraction from Cloud Mask (count of cloudy and probably cloudy / total count). AIRS additionally provides a coarse and fine resolution cloud fraction data product as well.
Cloud Fraction (Day only)
MODIS: Cloud Fraction from Cloud Mask (count of cloudy and probably cloudy / total count): Day
Cloud Fraction (Night only)
MODIS. Cloud Fraction from Cloud Mask (count of cloudy and probably cloudy / total count): Night
Cloud Liquid Water (or Total Cloud Liquid Water)
Cloud Liquid Water is the amount of liquid water (not vapor) per unit volume of air. It can be expressed either as grams per cubic meter of air or grams per kilogram of air.
Cloud Optical Thickness Combined (QA-weighted)
Combined Cloud Optical Thickness
Cloud Optical Thickness Ice Phase (QA-weighted)
Ice Cloud Optical Thickness
Cloud Optical Thickness Liquid Phase (QA-weighted)
Liquid Water Cloud Optical Thickness
Cloud Layer Pressure
The pressure for cloud layers at coarse resolution (low, middle, high).
Cloud Top Pressure (Day and Night)
Cloud Top Pressure (Day only)
Cloud Top Pressure (Night only)
Cloud Top Pressure at night
Cloud Top Temperature (Day and Night)
Cloud Top Temperature. The "Day and Night" designation is for a MODIS data product; AIRS additionally provides a coarse cloud top temperature data product for 3 layers (low, middle, and high).
Cloud Top Temperature (Day only)
Cloud Top Temperature during the day
Cloud Top Temperature (Night only)
Cloud Top Temperature at night
Atmospheric Temperature
Atmospheric temperature is, in literal terms, a measure of the average kinetic energy of air molecules in the atmosphere. It is expressed in units of degrees Kelvin or degree Celsius. The atmospheric temperature profiles are either made available as mean values for different atmospheric layers or at a number of fixed pressure levels or altitude.
Temperature Profile
The temperature of the atmosphere over a given location from the surface to the top of the stratosphere. AIRS provides an additional temperature profile data product estimated with microwave wavelength measurements only.
Tropopause Height
The tropopause is the boundary between the troposphere and the stratosphere. Tropopause height is the altitude of the tropopause over a given location.
Tropopause Pressure
The tropopause is the boundary between the troposphere and the stratosphere. Tropopause pressure is the atmosheric pressure of the tropopause over a given location.
Tropopause Temperature
The tropopause is the boundary between the troposphere and the stratosphere. Tropopause temperature is the atmosheric temperature over a given location.
Surface Air Temperature
Surface temperature measured by air thermometers - the temperature at a height of approximately 1 meter above ground level.
Surface Skin Temperature
Skin temperature refers to the temperature of the surface layer of the earth, in contrast to the meteorological definition of surface temperature measured by air thermometers--the temperature at a height of approximately 1 meter above ground level
Land Surface Temperature
The ambient temperature measured directly above the land surface. All MODIS Land Surface Temperature Products are described in the MODIS Land Surface Temperature Products User's Guide.
Sea Surface Temperature (SST)
Sea surface temperature is the temperature of the water at the ocean surface. This parameter generally indicates the temperature of the topmost meter of the ocean water column. Remote sensing measurements of SST actually measure the "skin temperature", the temperature at the top 0.1 mm of the water column, which is more strongly influenced by solar irradiance, and which may therefore differ somewhat from sea surface temperature.
Atmospheric Dew Point Temperature
The dew point (or dewpoint) of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for water vapor to condense into water. Dew point temperature can be visualized as an atmospheric profile, and is a different parameter to measure atmospheric water vapor content (humidity).
Total Column Liquid Water
The mean total integrated cloud column liquid water content, in units of kilograms per square meter. This is the mass of liquid water contained in clouds in an atmospheric column from surface to the top of the stratosphere above a square meter of the Earth's surface.
Total Column Water Vapor (microwave)
The total integrated column water vapor burden, with units of kilograms per square meter, estimated with microwave wavelengthe measurements only
Total Column Water Vapor
The total integrated column water vapor burden, with units of kilograms per square meter.
Atmospheric Water Vapor (QA-weighted)
MODIS provides Precipitable Water Vapor (IR Retrieval) Total Column
Atmospheric Water Vapor High (QA-weighted)
MODIS provides Precipitable Water Vapor (IR Retrieval) 700 to 300mb
Atmospheric Water Vapor Low (QA-weighted)
MODIS provides Precipitable Water Vapor (IR Retrieval) Surface to 920mb
Atmospheric Water Vapor (MLS)
Atmospheric water vapor concentration measured by the Microwave Limb Sounder
(Water) Vapor Mass Mixing Ratio (H2O Mass Mixing Ratio)
The water vapor mass mixing ratio is the ratio of the mass of water vapor to the mass of only the dry air in the air sample. Units are usually expressed as grams water per kilogram dry air.
Water Vapor above Cloud NIR Method (QA-weighted)
Water vapor concentration calculated from absorption in near infrared instrument bands, for cloudy atmospheric column conditions.
Water Vapor Clear Sky NIR Method (QA-weighted)
Water vapor concentration calculated from absorption in near infrared instrument bandsm for clear atmospheric column conditions.
Relative Humidity
The ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperatur
Relative Humidity with respect to Ice
An atmospheric variable expressing water vapor content, Relative Humidity with respect to Ice (RHI).
Relative Humidity over Liquid
Relative humidity over liquid or ice (see above) expresses which phase is thermodynamically stable at a given temperature and pressure.
Saturation Mass Mixing Ratio
The saturation mixing ratio is defined as the maximum mass of water vapor (grams) which can exist in amass of dry air (kilograms). The saturation mixing ratio has units of grams per kilogra
Geopotential Height
Geopotential Height (GPH), a meteorological variable used as a vertical scale in the atmosphere. AIRS provides an additional GPH data product estimated with microwave wavelength measurements only.
Atmospheric Ozone
Total Column Ozone is atmospheric concentration of ozone (O 3) in a vertical column of air. The Dobson unit (DU) is a measure of total ozone and is used for OMI and TOMS data in Giovanni. The MLS Ozone Profile is expressed in ppmv.
Carbon Monoxide (Total Column)
Total column concentration of carbon monoxide (CO) is the number of molecules of CO in an atmospheric column from the Earth's surface to the top of the stratosphere above a square centimeter of the surface.
Carbon Monoxide Volume Mixing Ratio
Aura MLS and Aqua-AIRS provide CO Vertical Profile. AIRS Giovanni provides volume mixing ratio of carbon monoxide in the atmosphere. The volume mixing ratio is the ratio of the number density of the gas to the total number density of the atmosphere (density is the number of molecules per unit volume)
Carbon Monoxide Effective Pressure (CO Effective Pressure)
The atmospheric pressure attributable to carbon monoxide at a given altitude in the atmosphere.
AIRS Giovanni provides CO Effective Pressure.
Carbon Monoxide Degrees of Freedom (CO Degrees of Freedom)
Degrees of freedom (DOF) indicate the amount of information in the retrieval of a particular constituent(determined by summing the diagonal elements of the averaging kernel).
Carbon Monoxide Verticality (CO Verticality)
AIRS Giovanni provides CO Verticality which is Sum of CO averaging kernels.
Bromine Monoxide
Atmospheric concentration of bromine monoxide (BrO). MLS provides BrO Vertical Profile.
Chlorine Monoxide
MLS Giovanni provides Profiles of Atmospheric concentration of chlorine monoxide (ClO)
Hydrochloric Acid
The atmospheric concentration of hydrochloric acid (HCl), also called hydrogen chloride.
Hydrogen Cyanide
The atmospheric concentration of hydrogen cyanide (HCN)
Hydroperoxyl radical
Atmospheric concentration of hydroperoxyl radical (HO2)
Hydroxyl Radical
Atmospheric concentration of hydroxyl radical (OH)
Hypochlorous Acid
Atmospheric concentration of hypochlorous acid (HOCl)
Methane Volume Mixing Ratio (CH4 Volume Mixing Ratio)
The volume mixing ratio of methane in the atmosphere. The volume mixing ratio is the ratio of the number density of the gas to the total number density of the atmosphere (density is the number of molecules per unit volume
Methane Effective Pressure (CH4 Effective Pressure)
The atmospheric pressure attributable to methane at a given altitude in the atmosphere.
Methane Degrees of Freedom (CH4 Degree of Freedom)
Degrees of freedom (DOF) indicate the amount of information in the retrieval of a particular constituent (determined by summing the diagonal elements of the averaging kernel).
Nitric Acid
Atmospheric concentration of nitric acid (HNO3)
Nitrogen Dioxide, Total Vertical Column Density
The number of molecules of NO2 in an atmospheric column (from the Earth's surface to the top of the atmosphere) above a square centimeter of the surface. In L2G Giovanni, NO2 data is provided only for near clear sky conditions (i.e only those NO2 retrievals are used in the analysis for which Cloud radiance fraction is less than 30%).
Nitrogen Dioxide, Tropospheric Vertical Column Density, 30% Cloud Screened
The number of molecules of NO2 in an atmospheric column from the Earth's surface to the top of the troposphere. In L2G Giovanni NO2 data is provided only for near clear sky conditions (i.e only those NO2 retrievals are used for which Cloud radiance fraction is less than 30%).
Nitrous Oxide
Atmospheric concentration of nitrous oxide (N 2O), also known as "laughing gas".
Nitrate
Nitrate is a dissolved form of nitrogen found in natural waters. Nitrate is a vital nutrient required for phytoplankton growth.
Backscattering coefficient, particulate matter (bbp) at 443 nm
The absorption and backscattering coefficients are inherent optical properties (IOP) with spectra which can be partitioned into subcomponents. The backscattering coefficient is partitioned into terms due to seawater, and suspended particulates.
Chlorophyll a concentration (Chl a)
Chlorophyll a concentration is expressed in units of mg/m-3, indicating the concentration of the photosynthetic pigment chlorophyll a (the most common "green" chlorophyll) in ocean, estuary, and lake waters. Total Chlorophyll is a data product generated by the NASA Ocean Biogeochemical Model (NOBM) based on data assimilation of remotely-sensed Chl a; it is not a data product produced by direct remote-sensing observations.
Chlorophytes
Chlorophytes are a variety of phytoplankton. Chlorophyte concentration is generated by the NASA Ocean Biogeochemical Model (NOBM); it is a model output product and is based on direct remote-sensing observations.
Coccolithophores
Coccolithophores are a variety of microscopic phytoplankton that create hard plates (coccoliths) which are cemented into a roughly spherical object called a coccosphere. Coccolithophore blooms are highly reflective and can cause erroneous results in ocean color radiometry algorithms. The NASA Ocean Biogeochemical Model (NOBM) provides coccolithophore concentration as a model output product; it is not based directly on remote-sensing observations. Emiliiania huxleyi is the most common coccolithophore observed with remote-sensin
Cyanobacteria
Cyanobacteria, also called blue-green algae, are a variety of phytoplankton. Cyanobacteria concentration is generated by the NASA Ocean Biogeochemical Model (NOBM) and is a model output product not directly based on remote-sensing observations.
Diatoms
Diatoms are a very common form of phytoplankton containing chlorophyll, and they usually create shells (frustules) made of silica. Diatoms are important primary producers of carbon in the oceans.
Diffuse attenuation coefficient at 490 nm (K490)
The diffuse attenuation coefficient at 490 nm (K490) is an indicator of water clarity. K490 expresses how deeply visible light in the blue to green region of the spectrum penetrates in the water column. The value of K490 represents the rate at which light intensity at 490 nm is attenuated with depth.
Mixed-layer depth
The mixed-layer depth is the depth of the bottom of the oceanic mixed layer. The mixed layer is an area at the ocean surface where temperature and salinity are somewhat uniform, making the seawater density uniform over depth. The uniformity of the mixed-layer is due to primarily to mixing processes caused by winds, salinity variation, and heat transfer.
Mixed-layer
Precipitation
Precipitation is liquid or frozen water (rain, snow) produced by weather systems. Precipitation is expressed in units of depth, or height of accumulation (mm, inches) of water that would fall on a area or "fill" a collector (rain gauge) to a measured depth.. Precipitation may also be expressed as the amount of water that falls in a given time period, i.e. mm/hour or mm/day.
Received Echo Powers
The CloudSat Cloud Profiling Radar (CPR) measures the backscattered power as a function of distance from the radar. The backscattered power is sampled every 240 m; there are 125 range bins, for a total vertical window of 30 km
Mean Surface Pressure
The average surface pressure calculated over a given time interval (commonly annual or monthly) for a location on the Earth's surface, expresed in millibars
Soil Moisture
Surface soil moisture (g cm-3): soil moisture (water content) in the top ~1 cm of soil, averaged over the retrieval footprint
Occurrence Frequency, Snow and Ice
The monthly snow, ice, and snow & ice frequency of occurrence for 1 degree grid cells is calculated as an average of all daily fractions of snow and ice for a given month.
Normalized Difference Vegetation Index (NDVI)
The mathematical formula for the Normalized Difference Vegetation Index (NDVI) is: NDVI = (NIR - VIS)/(NIR + VIS), where NIR is near-infrared radiation and VIS is visible wavelength radiation.
Vegetation Index (Enhanced)
A vegetation index is a measurement of the "greenness" of the Earth's land surface, with increasing greenness indicating increase ground coverage by growing vegetation. The enhanced vegetation index (EVI) was developed to optimize the vegetation signal with improved sensitivity in high biomass regions and improved vegetation monitoring through a de-coupling of the canopy background signal and a reduction in atmosphere influences
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Atmos Composition
