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You are here: GES DISC Home Giovanni - Interactive Visualization and Analysis Additional Features Users Manual Giovanni-3 Online Users Manual: Data Parameter Appendix

Giovanni-3 Online Users Manual: Data Parameter Appendix

Contributors: rchowdhury

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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. Click "Read More" or "more info" to access this additional information. We are currently transitioning to a new data parameter information system that will provide more detailed information about the parameters in Giovanni.



ATMOSPHERIC AEROSOLS



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) 
Read more


Aerosol Optical Depth

Aerosol Optical Thickness or Aerosol Extinction Coefficient

A measure of radiation extinction at the encounter of aerosol particles in the atmosphere.

The extinction or total aerosol optical depth is a measure of radiation extinction due to aerosol scattering and absorption. Aerosol Total Optical Thickness is available through Giovanni at 550 nm from MODIS; at 865 and 869 nm from SeaWiFs;  at 443, 555, 670, and 865 nm from MISR; and at a number of wavelengths between 342 and 500 nm from Aura/OMI. OMI also provides Aerosol Absorption Optical Depth for near-UV wavelengths.   The MISR AOD is described in the MISR: Level 2 Aerosol Retrieval ATBD.
Read more Red Dice Information for Educators (DICCE Project)


Deep Blue Aerosol Optical Depth (Land Only)

Aerosol optical depth is a measure of radiation extinction due to scattering and absorption by aerosol particles in the atmosphere. Deep Blue AOD at 550 nm for MODIS calculates AOD over bright areas such as deserts where the standard MODIS AOD algorithm does not work.

Red Dice Information for Educators (DICCE Project)


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 a number of wavelengths between 342 and 500 nm . 
Read more


Aerosol Single Scattering Albedo

Single scattering albedo is the ratio of scattering optical depth to the total optical depth (scattering + extinction) of the atmosphere.  


Read more

 


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.  
Read more

Read more about "parameter weighting" and "time-averaging", operations used for the Aerosol Small Mode Fraction calculation (optical depth based weighting).


Aerosol Mass Concentration(QA-weighted) - Land

Aerosol Mass Concentration (QA-weighted) - Ocean

MODIS provides columnar aerosol mass concentration over land, and over ocean.
Read more Red Dice   Information for Educators (DICCE Project):  Mass Concentration (Land)Mass Concentration (Ocean)


Aerosol Angstrom Exponent or Angstrom Coefficient

A measure of the spectral dependence 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 color data processing (as part of atmospheric correction algorithm) provides Angstrom coefficient based on aerosol optical depth values between 510-865 nm for SeaWiFS, and between 531-869 nm for MODIS-Aqua(QA-weighted). 
Read more


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 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.
more info


Aerosol Effective Radius
Aerosol radiative effects 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 micron light scattering.
Read more


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.


RADIATION & FLUX


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.


Longwave flux
The outgoing longwave flux is the upwelling thermal radiative flux, often called the "outgoing longwave radiation" or "OLR". In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics. (NOAA)  Longwave radiation has a spectral wavelength greater than 4 µm. 
Red Dice Information for Educators (DICCE Project)


Net flux
The net flux is the incoming solar flux minus the outgoing reflected (shortwave) and thermal (longwave) radiation. If the flux in a region is positive, the Earth is being warmed by the sun in that region, while cooling regions have a negative flux. (Visible Earth)


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.


Remote sensing reflectance
The ratio of radiance leaving the water (upwelling) to irradiance incident on the water (downwelling).  So-named because it indicates the effective reflectance of a body of water when viewed by a remote sensor such as an airborne or satellite radiometer. (Definition courtesy of HobiLabs.)


Photosynthetically Available Radiation (PAR)
Photon flux density (photons per second per square meter) within the visible wavelength range (usually 400 to 700 nm). This parameter indicates the total energy available to plants for photosynthesis, and is thus a key parameter for biological and ecological studies. Sometimes called Photosynthetically Active Radiation. (Definition courtesy of Hobilabs)
Red Dice Information for Educators (DICCE Project)

 


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 wavelengths.


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 units of kiloJoules (kJ) per square 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.
Read more


Local Noon Erythemal UV Irradiance
This quantity is 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 susceptibility of Caucasian skin to sunburn(erythema). As indicated by the name, this quantity is determined for local noon solar angles.
Read more


Latent Heating

Latent Heating is the monthly mean of the latent heating release in 0.5° x 0.5° boxes from 40°N x 40°S at each vertical level.  (3A12)


Shortwave flux
Shortwave radiation (SW) is a term used to describe the radiant energy in the visible (VIS), near-ultraviolet (UV), and near-infrared (NIR) wavelengths. The wavelength range is not always exactly defined, as there is no standard cut-off for the NIR. Shortwave radiation may be as broadly defined as between 0.1 and 5.0 µm) or as narrow as 0.2 to 3.0 µm, as there is little radiation flux (in terms of W/m2) to the Earth's surface below 0.2 µm or above 3.0 µm. (Wikipedia) In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics.
  Red Dice Information for Educators (DICCE Project)

 


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.

Read more



CLOUDS



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 filamentousc 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 condensation nuclei 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
- Read more

Cloud Effective Radius Ice Phase (QA-weighted)
Effective particle radius for ice clouds-
- Read more

Cloud Effective Radius Liquid Phase (QA-weighted)
Effective particle radius for liquid water clouds
- Read more


Radiative Cloud Fraction (UV based)

The radiative cloud fraction is an effective cloud fraction. It characterizes the fraction of the incoming radiation that is scattered by clouds. It is provided in OMI products. 
Read more


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.
Read more 

Red Dice  Information for Educators (DICCE Project)

Cloud Fraction (Day only)
MODIS: Cloud Fraction from Cloud Mask (count of cloudy and probably cloudy / total count): Day
Read more

Cloud Fraction (Night only)
MODIS. Cloud Fraction from Cloud Mask (count of cloudy and probably cloudy / total count): Night 
Read more


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.
Read more

Cloud Liquid Water (TRMM Monthly)

Cloud Liquid Water is the monthly mean of the cloud liquid water content in 0.5° x 0.5° boxes from 40°N x 40°S at each vertical layer.


Cloud Optical Thickness Combined (QA-weighted)
Combined Cloud Optical Thickness
Read more

Cloud Optical Thickness Ice Phase (QA-weighted)
Ice Cloud Optical Thickness.
Read more

Cloud Optical Thickness Liquid Phase (QA-weighted)
Liquid Water Cloud Optical Thickness.
Read more


Cloud Ice

Cloud Ice is the monthly mean of the cloud ice water content in 0.5° x 0.5° boxes from 40°N x 40°S at each vertical layer.


Cloud Layer Pressure
The pressure for cloud layers at coarse resolution (low, middle, high).


Cloud Top Pressure (Day and Night)
Read more

Cloud Top Pressure (Day only)
Read more

Cloud Top Pressure (Night only)
Cloud Top Pressure at night.
Read more


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).
Read more

Cloud Top Temperature (Day only)
Cloud Top Temperature during the day.
Read more

Cloud Top Temperature (Night only)
Cloud Top Temperature at night .
Read more



ATMOSPHERIC TEMPERATURE, PRESSURE, & WINDS



Average Surface Temperature
Average surface temperature of the Earth is the combined temperature of the near-surface air temperature and the sea surface temperature.

Red DiceInformation for Educators (DICCE Project)  

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.
Read more

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.

Red Dice  Information for Educators (DICCE Project)


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 atmospheric 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. 
Read more

Red DiceInformation for Educators (DICCE Project)  


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

Red DiceInformation for Educators (DICCE Project)


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.
Red DiceInformation for Educators (DICCE Project)


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.  Red DiceInformation for Educators (DICCE Project)


Near surface wind magnitude

Near surface wind magnitude is a measure of the speed of air movement relative to a fixed point on the Earth. It expresses the strength of the horizontal movement of the air near the Earth’s surface.   Red DiceInformation for Educators (DICCE Project)

 



ATMOSPHERIC HUMIDITY & WATER VAPOR



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).
Read more


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.
Read more


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.
Read more


Total Column Water Vapor
The total integrated column water vapor burden, with units of kilograms per square meter.
Read more


Atmospheric Water Vapor (QA-weighted)
MODIS provides Precipitable Water Vapor (IR Retrieval) Total Column 
Read more


Atmospheric Water Vapor High (QA-weighted)
MODIS provides Precipitable Water Vapor (IR Retrieval) 700 to 300mb.
Read more

Atmospheric Water Vapor Low (QA-weighted)
MODIS provides Precipitable Water Vapor (IR Retrieval) Surface to 920mb.
Read more


Atmospheric Water Vapor (MLS)
Atmospheric water vapor concentration measured by the Microwave Limb Sounder.
Read more


(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 Volume Mixing Ratio

The volume mixing ratio is the ratio of the number density of the gas (water vapor) to the total number density of the atmosphere (density is the number of molecules per unit volume).

 


Water Vapor above Cloud NIR Method (QA-weighted)
Water vapor concentration calculated from absorption in near infrared instrument bands, for cloudy atmospheric column conditions. 
Read more


Water Vapor Clear Sky NIR Method (QA-weighted)
Water vapor concentration calculated from absorption in near infrared instrument bandsm for clear atmospheric column conditions.
Read more


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 temperature.
Read more   Red DiceInformation for Educators (DICCE Project)


Relative Humidity with respect to Ice
An atmospheric variable expressing water vapor content, Relative Humidity with respect to Ice (RHI).
Read more


Relative Humidity over Liquid
Relative humidity over liquid or ice (see above) expresses which phase is thermodynamically stable at a given temperature and pressure.
Read more


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 kilogram.
Read more


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.
Read more



TRACE GASES



 

Atmospheric Ozone

Column Amount Ozone

 

Total Column Ozone, or Column Amount Ozone, is the atmospheric density of ozone (O3) 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.

Read more

Red DiceInformation for Educators (DICCE Project)


Bromine Monoxide
Atmospheric concentration of bromine monoxide (BrO). MLS provides BrO Vertical Profile.
Read more


Carbon Dioxide
The carbon dioxide parameter is the CO2 mole fraction  This is a total tropospheric column property, and is in mole fraction units (data x 106 = ppm by volume).

Red DiceInformation for Educators (DICCE Project)


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.

Red DiceInformation for Educators (DICCE Project)
Read more


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).
Red DiceInformation for Educators (DICCE Project)

Read more


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.

Red DiceInformation for Educators (DICCE Project)

 


Chlorine Monoxide
MLS Giovanni provides profiles of atmospheric concentration of chlorine monoxide (ClO).
Read More

 


Formaldehyde (HCHO)

The atmospheric concentration of formaldehyde, chemical formula HCHO.

Read More

 


Hydrochloric Acid
The atmospheric concentration of hydrochloric acid (HCl), also called hydrogen chloride.
Read more


Hydrogen Cyanide
The atmospheric concentration of hydrogen cyanide (HCN) 
Read more


Hydrogen deuterium oxide (HDO) Volume Mixing Ratio

The volume mixing ratio of HDO 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).

 


Hydroperoxyl radical
Atmospheric concentration of hydroperoxyl radical (HO2)
Read more


Hydroxyl Radical
Atmospheric concentration of hydroxyl radical (OH)
Read more


Hypochlorous Acid
Atmospheric concentration of hypochlorous acid (HOCl).
Read more


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.

Red DiceInformation for Educators (DICCE Project)


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).


Methane, Total Column

Total Column Methane is the atmospheric density of methane (CH4) in a vertical column of air. 


Nitric Acid
Atmospheric concentration of nitric acid (HNO3)

Red DiceInformation for Educators (DICCE Project)

Read more


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%).
Red DiceInformation for Educators (DICCE Project)

Read more


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%).

Red DiceInformation for Educators (DICCE Project)


Nitrous Oxide
Atmospheric concentration of nitrous oxide (N 2O), also known as "laughing gas".
Read more

 


Sulfur Dioxide

The atmospheric concentration of sulfur dioxide (SO2).

Red DiceInformation for Educators (DICCE Project)

Read more

 



OCEAN COLOR RADIOMETRY



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. SeaWiFS and MODIS provide absorption coefficient for seawater, phytoplankton, and the combined coefficient for dissolved and detrital particulate matter (acdm) at 443 nm .
   Models are described in Chapter 10 (QAA) and Chapter 11 (GSM) of IOCCG Report #5 (PDF).


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.
Models are described in Chapter 10 (QAA) and Chapter 11 (GSM) of IOCCG Report #5 (PDF). 


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.

Red DiceInformation for Educators (DICCE Project)


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-sensing.


Colored dissolved organic matter (CDOM)
Dissolved organic matter and particulate organic matter (or particulate organic carbon, POC, defined below) are distinguished as the fractions of organic matter in water samples that are either passed through or retained by a filter (nominally a glass fiber filter with 0.7 µm pore size), respectively.   Colored (also called chromophoric) dissolved organic matter (CDOM) is optically detectable, i.e., it absorbs light, most strongly in the blue to UV range.  In sufficient concentrations, CDOM will thus provide color to the water in which it is dissolved.  High concentrations of CDOM in ocean waters interfere with accurate estimation of chlorophyll a concentration in remotely-sensed data.


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.


Euphotic depth

The euphotic depth is the depth at which light intensity falls to 1% of the value at the surface of a body of water. It refers to the "lighted zone" of the water column in which photosynthesis can take place. Euphotic depth is influenced by phytoplankton, colored dissolved organic matter, and suspended particulate matter.    Red Dice Information for Educators (DICCE Project)


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. 

 


Normalized fluorescence line height (NFLH)

Normalized Fluorescence Line Height (in mW cm-2 µm-1 sr-1) is a measure of the solar stimulated chlorophyll-a fluorescence, measured with the 678nm MODIS band.

 


Particulate Inorganic Carbon (PIC)

Particulate inorganic carbon represents biogenic particles composed of calcium carbonate (CaCO3).   CaCO3 is produced by several varieties of phytoplankton, notably coccolithophorids and foraminifera.   It is also produced by zooplankton (pteropods and heteropods), but these organisms are too large to be detected by remote sensing.

 


Particulate Organic Carbon (POC)

Particulate organic carbon (POC) refers to a size class of organic carbon in the oceans, differentiated from dissolved organic carbon (DOC) by the size of a filter, nominally a glass fiber filter with pore size 0.7 µm.  Organic carbon retained by the filter is considered particulate.  POC generally represents living phytoplankton biomass and organic detritus, but some living organic matter (bacteria and viruses) will pass through the filter and thus be considered as DOC.

 

 



HYDROLOGY



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.
Read more

Red DiceInformation for Educators (DICCE Project)

Precipitation Ice
Precipitation Ice is the monthly mean of the precipitation ice content in 0.5° x 0.5° boxes from 40°N x 40°S at each vertical layer.

Precipitation water
Precipitation Water is the monthly mean of the precipitation water content in 0.5° x 0.5° boxes from 40°N x 40°S at each vertical layer.

Precipitable Water

Precipitable water (measured in millimeters or inches) is the amount of water in a column of the atmosphere. The precipitable water value is the depth that would be achieved if all the water in that column were precipitated as rain. (Wikipedia)


Rain rate (3A12)
Rain Rate is the monthly mean of the instantaneous rain rate at the surface in 0.5° x 0.5° boxes from 40°N x 40°S. (3A12)

Stratiform Rain Rate (3A12)
Stratiform Rain Rate is the monthly mean of the instantaneous stratiform rain rate at the surface in 0.5° x 0.5° boxes from 40°N x 40°S.

Rain Rate (3B43)
Monthly mean of satellite/gauge precipitation estimate.(3B43)

Conditional Mean Rain Rate (3A25)
Mean of non-zero estimated surface rain below clutter (See 2A25 algorithm user guide) at a horizontal resolution of 0.5° x 0.5°.

Convective Mean Rain Rate (3A25) or Convective Rain Rate (3A12)
Mean of non-zero estimated surface rain conditioned on convective rain at a horizontal resolution of 5° x 5° or 0.5° x 0.5°.  The 3A12 Convective Rain Rate is the same quantity calculated with a different algorithm, and only available at 0.5° x 0.5° resolution.

Stratiform Mean Rain Rate (3A25)
Mean of non-zero estimated surface rain conditioned on stratiform rain at a horizontal resolution of 5° x 5° or 0.5° x 0.5°.

Unconditional Mean Rain (3A25)
Mean of zero and non-zero estimated surface rain at a horizontal resolution of 5° x 5° or 0.5° x 0.5°.

Unconditional Convective Mean Rain Rate (3A25)
Mean of zero and non-zero estimated surface rain conditioned on convective rain at a horizontal resolution of 5° x 5° or 0.5° x 0.5°.

Unconditional Stratiform Mean Rain Rate (3A25)
Mean of zero and non-zero estimated surface rain conditioned on stratiform rain at a horizontal resolution of 5° x 5° or 0.5° x 0.5°.

Rain Rate (3B42)
Adjusted GPCP (Global Precipitation Climatology Project) precipitation estimate.


Convective Rain Pixel Count (3A25)
The number of non-zero estimated surface rain pixel counts conditioned on convective rain, at a horizontal resolution of 5° x 5° or0.5° x 0.5°.

Stratiform Rain Pixel Count (3A25)
The number of non-zero estimated surface rain pixel counts conditioned on stratiform rain, at a horizontal resolution of 5° x 5° or0.5° x 0.5°.

Rain Pixel Count (3A25)
The number of non-zero estimated surface rain pixel counts at a horizontal resolution of 5° x 5° or 0.5° x 0.5° for one month.

Total Pixel Count (3A25)
The angle between the initial and final paths traveled by a scattered particle or photon.


Relative error (3B43)
Monthly mean of satellite/gauge relative error estimate. (3B43)

Relative Error (3B42)
Adjusted GPCP (Global Precipitation Climatology Project) relative error estimate.


Snowfall rate
Snowfall Rate is a measure of the intensity of snowfall. It is measured by calculating how much snow falls to the earth surface per unit area per unit of time. The units are kilograms per square meter per second (kg/m2/s).
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LAND



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, expressed 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.
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Snow depth
The actual depth of snow on the ground, measured in units of length (inches or centimeters).
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Snow mass
The mass of snow, in kilograms, on a square meter of land surface. This is a more direct measure of the amount of water contained in snow than snow depth or snow occurrence frequency.
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Fractional snow-covered area
The standard MODIS snow product is a daily fractional snow map, generated from the daily 500 meter resolution MODIS snow product (acquired using the 500-meter resolution bands) by collecting the observations and calculating the fraction of snow observations (pixels) mapped into a 0.25 degree grid cell. Each 0.25 degree grid cell will have about 80 pixels, each providing a percentage of snow cover. Average fractional snow cover is calculated by summing the 0-100% snow values; the 0% fraction snow class is included in the sum, then dividing by the count of observations included in the sum.  Fractional snow cover is more quantitative than snow occurrence frequency, which only indicates whether or not snow was present.
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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.

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Enhanced Vegetation Index (EVI)
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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