Greenhouse gases observing satellite GOSAT  "IBUKI"

Glossaries

A
Term Description
Aerosol A microscopic liquid or solid particle floating in the atmosphere.
Along-track direction Flight direction of the satellite on the spacecraft fixed coordinates.
Apodization It represents a convolution procedure using a pseudo weighting function (apodizing function) as a function of the optical path difference when the interferogram is Fourier-transformed into the spectrum. The interferogram is multiplied by the apodizing function before the Fourier transform. In the case of no apodization, the instrumental line shape function is the sinc function. Generally, the apodization makes the full width at half maximum of a instrumental line shape function larger, although unphysical oscillation of the sinc function is suppressed.
Atmospheric transport model A numerical model to estimate the distribution of an atmospheric constituent of interest (e.g., CO2, CH4) and its variation under certain condition. In case of CO2 (or CH4), the model simulates the variation of its concentration based on the existing flux data, with meteorological data (air temperature, wind parameters, etc.) and chemical reactions in the atmosphere taken into consideration.
B
Term Description
(Light) Band pass filter An optical filter which passes only light with a certain wavelength range and rejects (attenuates) light with wave numbers outside that range.
Beam splitter An optical device which splits a light flux into two. A part of the light injected into the beam splitter reflects back and the other part penetrates. A beam splitter which splits polarization components is called a polarized beam splitter.
C
Term Description
Calibration stage GOSAT L1 data products will undergo the following three calibration steps before released and distributed to users.
  1. (i) Initial check : Visual check on the result of processing of certain observation data, in order to confirm calibration results of the sensor characteristics.
  2. (ii) Calibration analysis : Check the preliminarily checked products after the initial sensor calibration activity.
  3. (iii) Confirmation after the release : Check to be performed after releasing the products to limited users, to see if any problem with the products is reported or not after a certain period of time.
The products are categorized into four stages in the process of these calibration steps, namely U (Unchecked), P (Preliminarily checked), Ca (Calibrated), and C (Confirmed). These stages are termed the "calibration stages".
Carbon emission inventory Information on the human-induced emission of carbon dioxide etc. for areas obtained based on the investigation.
Carbon flux estimation model A model to estimate the emission and absorption of carbons for a region (a certain scale which the entire globe is divided into), based on the distributions of CO2, etc. in the atmosphere obtained by GOSAT or otherwise together with meteorological data.
Check stage GOSAT L4 data products will undergo the following three check steps before released and distributed to users.
  1. (i) Initial check : Visual check on the result of the product generated by the carbon balance analysis calculated from the L2 products and data of the ground-based observation stations.
  2. (ii) Check analysis : Check the preliminarily checked products by the expert users for a certain period of time.
  3. (iii) Confirmation after the distribution : Check to be performed after releasing the products to limited users, to see if any problem with the products is reported or not after a certain period of time.
The products are categorized into four stages in the process of these check steps, namely U (Unchecked), P (Preliminarily checked), Ch (Checked), and C (Confirmed). These stages are termed the "check stages".
Co-I (Co-Investigator) An investigator who carries out the research on a theme selected in the RA and is approved and registered as Co-I (Co-Investigators) by the Three Parties.
Corner cube A trihedral made up of three planer reflectors which are perpendicular to each other. The light injected into the trihedral bounces on each of the three planes and will always return to the incident direction.
Cross-track direction The direction perpendicular to the flight direction of the satellite on the satellite fixed coordinates.
D
Term Description
Dichroic filter An optical filter which passes only light with specific wave number band and reflects the other.
E
Term Description
Evaluation stage GOSAT L3 products will undergo the following two evaluation steps before released and distributed to users.
  1. (i) Initial check : Visual check of L3 products processed from certain L2 products, in order to evaluate the results.
  2. (ii) Confirmation after the release : Check to be performed after releasing the products to limited users, to see if any problem with the products is reported or not after a certain period of time.
The products are categorized into three stages in the process of these validation steps, namely U (Unchecked), E (Evaluated), and C (Confirmed). These stages are termed the "evaluation stages".
F
Term Description
Fourier Transform Spectrometer (FTS) An observing instrument which observes the incident interfering signal (interferogram) acquired with the interferometer, and Fourier-transforms the signal into radiance spectra. In the GOSAT Project, the spectrometer is applied to measure the absorption or radiance spectra of CO2, CH4, etc.
Frame A frame is the unit for CAI products, defined by dividing one revolution length of GOSAT�fs trajectory mapped on the ground surface into 60. A frame of CAI data is the minimum unit to archive CAI L1B, CAI L1B+, and most of CAI L2 products.
Full-width at half maximum (FWHM) An indicator of the spread (width) of a chevron-shaped function, such as instrument function. It is defined as the difference in the wavelengths or wave numbers at the two points where the value of the unimodal function marks a half of its maximum.
G
Term Description
Gain The signal amplification factor used for amplifying signals to an appropriate signal processing level (voltage), set up by using commands for every brightness (light intensity) of observation targets. For GOSAT, there are three gain setting levels each for FTS and CAI: L (Low), M (Middle), and H (High).
Gaseous column amount(column abundance) The total amount of gas present in the vertical air column per unit area. (Number of molecules per unit area).
Gaseous concentration profile Vertical distribution of gaseous concentrations (Number of molecules per unit area or volumetric ratio of the target species per unit area)
Geometric correction A process of correcting the positional information in observation data, such as band-to-band registration, correction of the latitude and longitudes of observation points based on elevation information, etc.
I
Term Description
Instrument function calibration Calibration performed with consideration given to the wavelength dependence of the sensitivity.
Interferogram Patterns of interferometric light obtained as a result of the following steps: i) split incident light into two beams using the beam splitter, ii) change one of the path lengths of the two split beams, and iii) let the two beams of light interfere with each other again.
Inverse model A method (model) to estimate the sources and sinks and the emission and absorption of atmospheric constituents of interest, such as CO2, using observation data such as the GOSAT data, with the combined use of atmospheric transport models and statistical techniques.
L
Term Description
Land ecosystem model A model which expresses the exchange processes of heat, water, carbon, etc. (e.g., photosynthesis, respiration) between the land vegetation ecosystem, comprised of forest, pasture, etc., and the atmosphere.
M
Term Description
Maneuver An activity to control the attitude, speed, etc., consequently orbit, of the spacecraft, by thrusting its control engine, etc. It is performed in order to maintain or change the spacecraft to the expected attitude or orbit.
O
Term Description
Observation in lattice point Regular observation of FTS on the fixed ground points (lattice points). In all the five pointing modes (depending on the number of points per scan, 1, 3, 5, 7, or 9), the sensor observes the same footprint every recurrence after three days.
Observation request A request for specific data acquisition for a specific purpose, such as an observation over a calibration/validation site, which is not covered by GOSAT�fs routine observation (in lattice point).
Original data GOSAT data products provided by JAXA or NIES. This should be distinguished from the data obtained as a result of the research carried out by RA Investigators.
P
Term Description
PI (Principal Investigator) The abbreviation of the Principal Investigator, who represents the group of investigators who engage in the research activities on the research theme adopted in the RA and serves as the contact person to the Three Parties on all matters relating to the joint research agreement.
Polarization Light of which the electric or magnetic field oscillates in a specific direction.
Product Digital information or its electronic file, containing the processed results of GOSAT observation data, prepared in the predetermined format for distribution to users. Product is also said as data product.
Product distribution request A request made by an RA investigator for provision of data products necessary for implementing the research on the selected theme.
R
Term Description
Radiometric calibration Conducting correct engineering conversion of integer numbers (digital numbers, DN) to radiance values, by using various kinds of observation data and conversion formula.
RA Investigator An investigator who carries out the research on a theme selected in the RA and is registered as PI (Principal Investigators) or Co-I (Co-Investigators) by the Three Parties.
RA Selection and Evaluation Committee (The Committee) A committee which selects research proposals submitted in response to the RA and provides the Three Parties with advice in the process of selecting research themes. The committee also evaluates the research progress as well as results reported by the RA Investigators and advises the Three Parties of the evaluation results.
Rectangle A rectangle (60 deg. x 30 deg. (lat. x lon.)) is the unit to archive CAI L3 normalized-difference vegetation index (NDVI) product. The globe is divided into 36 rectangles, separating from 25 degree west by 60 degree in longitudinal eastward direction, and from 90 degree north by 30 degree in latitudinal southward direction.
Region A region is the unit defined for L4A data product. The globe is divided into 64 sub-continental regions and a net source and sink of greenhouse gases is estimated per each region. L4A data product shows the monthly estimated net source and sink of greenhouse gases for 64 regions in a global map.
S
Term Description
Scan The unit of acquisition of one interferogram by FTS.
Scene (i) FTS scene
FTS scene of L1 data product is defiened to have a span covered by the observation performed in a time 1/60 of the one-revolution period; the start of the first scene corresponds to the ascending node passing time. A scene of FTS data is the unit to achive FTS L1 data products.

(ii)CAI scene
A CAI scene is defined to have a span covered by the observation performed in one-revolution; the start of the scene corresponds to the ascending node. A scene of CAI data is the unit to archive CAI L1A products. TANSO-CAI usually acquires data during the daytime area on the ground ; accordingly, a CAI scene has a strech of data for the continuous daytime area (nighttime area are not included).
Science Team An organization established for the purpose of providing the GOSAT Project with scientific advice.
Specific point observation Observation over specific ground points other than the lattice points observed in the routine observation, such as calibration/validation sites, observation points along a natural gas pipeline, etc.
Spectral resolution The minimum difference in wavelength, in case of the wavelength resolution, or wave number, in case of the wave number resolution, that the spectrometer can determine.
Sunglint Specular reflection of the sunlight on the water surface, in general. In this phenomenon, the specular reflection point is on the same plane as the sun and the sensor, and the reflection angle is the same as the incidence angle. However, as the intensity of the reflected light reaching the sensor is the strongest in the vicinity of such a reflection point, FTS observes the vicinity of specular reflection points for its water-surface observation.
Sun-synchronous sub-recurrent orbit An orbit combining a sun-synchronous orbit and a sub-recurrent orbit, having the characteristics of the two. In the former orbit, the orbital plane of the satellite rotates once while the earth revolves the sun once (one revolution). In the latter orbit, the satellite returns to almost the same orbit at a certain interval (recurrence). GOSAT returns to almost the same footprint after 44 orbits in three days. The descending node time (local solar time) is adjusted to around 13 o�fclock, and the local time at the nadir point of the satellite is almost the same time at medium and low latitudes.
V
Term Description
Validation stage GOSAT L2 and L3 products will undergo the following three validation stages before released and distributed to users.
  1. (i) Initial check : Visual check on the result of processing of certain observation data, in order to confirm the validity of calibration of the sensor characteristics and data processing algorithms.
  2. (ii) Validation analysis : Comparison of GOSAT observation data with validation data, in order to evaluate the reliability of the products.
  3. (iii) Confirmation after the release : Check to be performed after releasing the products to limited users, to see if any problem with the products is reported after a certain period of time.
The products are categorized into four stages in the process of these validation steps, namely U (Unchecked), P (Preliminarily checked), V (Validated), and C (Confirmed). These stages are termed the "validation stages".

Glossary                /                Abbreviation                 /                User Category

Glossary                /                Abbreviation                 /                User Category

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