ICON The Far Ultra Violet Imaging Spectrograph Dayside Images

FUV Dayside Images

https://doi.org/10.48322/w3qs-ed95

2024-05-02 00:00:00Z

The FUV instrument takes 2D images of the Earth’s horizon in the Far ultraviolet. The imager is pointing approximately 90 degrees to the spacecraft motion, similar to looking out of the side window of a car as it drives down the road. Onboard electronics read the image 8 times per second and perform Time Delay Integration (TDI) to remove the motion-blur from the images. A turret is used to steer the field of view of the instrument left to right to ensure it always looks along the magnetic meridian (towards the magnetic pole).

  This describes the data product for ICON FUV Daytime O/N2 (DP 2.4). The ratio of oxygen to nitrogen in the thermosphere is obtained from the two channels of ICON FUV instrument data in, through an inversion process described in https://doi.org/10.1007/s11214-018-0477-6.  The L2 FUV Daytime files are produced from the L1 FUV files.

National Aeronautics and Space Administration; Dr. Andrew W. Stephan; Dr. Thomas Immel

Online

Open

NetCDF

Please acknowledge Dr. Farzad Kamalabadi and Dr. Thomas Immel. Please acknowledge the Data Providers and CDAWeb when using these Data.

Online

Open

NetCDF

None

Please acknowledge Dr. Farzad Kamalabadi and Dr. Thomas Immel. Please acknowledge the Data Providers and CDAWeb when using these Data.

PT12S

Epoch Time

Epoch

Sample time, midpoint of exposure. Number of msec since Jan 1, 1970.

PT12S

ms

0

6000000000000

-999

Disk Short Wave Emission

ICON_L24_1356_Emission

Short wave disk column emisison rate.

PT12S

Rayleighs

-100.000000

10000000000

-999

Ap Index

ICON_L24_Ap

Value of Ap used in the forward model, as a function of time. These data are from http://www-app3.gfz-potsdam.de/kp_index/. These are the tabulated Kp values from GFZ German Research Centre for Geosciences at the Helmholtz Centre Potsdam.

PT12S

0

400

-999

Line of Sight Zenith Angle

ICON_L24_Disk_LOS_Zen_Angle

Line of sight zenith angle corresponding to disk retrieval.

PT12S

degrees

0

180

-999

Retrieved Disk Geodetic Latitude

ICON_L24_Disk_Latitude

Geodetic latitude (WGS84) corresponding to disk retrieval.

PT12S

degrees

-90

90

-999

Retrieved Disk Geodetic Longitude

ICON_L24_Disk_Longitude

Geodetic longitude (WGS84) corresponding to disk retrieval.

PT12S

degrees

-90

90

-999

Magnetic Latitude on Disk

ICON_L24_Disk_Magnetic_Latitude

Quasi-Dipole Magnetic Latitude at 150 km at Disk Retrieval location, in degrees.

PT12S

degrees

-90

90

-999

Magnetic Longitude on Disk

ICON_L25_Magnetic_Longitude

Quasi-Dipole Magnetic Longitude at 150 km at Disk Retrieval location, in degrees.

PT12S

degrees

0

360

-999

Retrieved disk column O/N2

ICON_L24_Disk_ON2

Retrieved column O/N2 ratio on the disk.

PT12S

Dimensionless

0

200

-999

Retrieved Qeuv on the Disk

ICON_L24_Disk_QEUV

Diagnostic Effective solar EUV energy flux, mmW/m2 - multiply by model 4 * model 7 to obtain solar flux required for dayglow fit on the disk.

PT12S

mW/m2

0

100000002004087734272

-999

Quality Flags

ICON_L24_Disk_Retrieval_Flags

Disk retrieval quality flag, where 0 = nominal retrieval, 1 = Disk short/long wave ratio out of model range, 2 = Disk O/N2 value out of expected range, 3 = Disk P/N2 uncertainty out of expected range.

PT12S

0

10

-999

Retrieved Disk Solar Zenith Angle

ICON_L24_Disk_SZA

Solar zenith angle corresponding to disk retrieval.

PT12S

degrees

0

180

-999

Retrieved Disk Column O/N2 Uncertainty

ICON_L24_Disk_Sigma_ON2

Uncertainty in retrieved column O/N2 ratio on the disk, based on spread in reported uncertainty in input data.

PT12S

Dimensionless

0

200

-999

F10.7 Used in Retreival

ICON_L24_F107

Unscaled value of F10.7 used as an input to the inversion process, as a function of time. These data are from ftp://ftp.seismo.nrcan.gc.ca/spaceweather/solar_flux/fluxtable.txt. These are the solar radio flux values tabulated from the Space Weather Canada which is a part of Natural Resources Canada.

PT12S

sfu

0

500

-999

Initial Duess Disk Column O/N2

ICON_L24_Initial_Disk_ON2

Initial guess of column O/N2 ratio on the disk.

PT12S

Dimensionless

0

200

-999

Data Collection Mode

ICON_L24_Instrument_Mode_Flag

Data collection mode of FUV instrument
1 = Dayside science
2 = Nightside science
3 = Calibration
4 = Nadir
5 = Conjugate
6 = Stars
7 = Ram
8 = Off Target
9 = Engineering
13 = Unknown.

PT12S

0

127

127

Disk Long Wave Emission

ICON_L24_LBH_Emission

Long wave disk column emisison rate.

PT12S

Rayleighs

-100

10000000000

-999

Quality Flag of Profiles

ICON_L24_Level_1_Quality_Flag

QUALITY_FLAG is an indicator of data quality =
0 = No errors or quality conditions, LVLH
1 = No errors or quality conditions, R-LVLH
2 = Lunar calibration
3 = Insufficient high voltage
4 = Nadir calibration
5 = Zero wind calibration
6 = Bad pointing
7 = S/C attitude slew
8 = Conjugate observation
9 = Stellar calibration
10 = Unreliable background subtracted
17 = unspecified error condition.

PT12S

N/A

0

127

127

Limb Retrieval Flags

ICON_L24_Limb_Retrieval_Flags

Limb retrieval quality flag, where 0 = no limb inversion, 1 = retrieval nominal, 2 = number of iterations in retrieval algorithm reaches 10 without convergence, 3 = one or more inversion model parameters hits a priori upper or lower limit, 4 = altitude of peak intensity too close to boundary, 5 = standard deviation of one or more variables exceeds expected limit, 6 = Chi-squared value is outside of expected range - either too large or too small, 7 = one or more uncertainties is outside of expected range.

PT12S

integer

0

10

-999

Local Time on the Disk

ICON_L24_Local_Solar_Time_Disk

Local solar time of the retrieval on the disk, in hours.

PT12S

hours

0

24

-999

Covariance Matrix of the Model Parameters

ICON_L24_Model_Covariance

Covariance matrix of the model parameters found by the algorithm, as a function of time.

PT12S

unitless scalars

-1000

1000

-999

Lower Limits of the Model Parameters

ICON_L24_Model_Lower_Limit

Diagnostic Lower limits of the model parameters used by the algorithm, as a function of time.

PT12S

unitless

-1000

1000

-999

Upper Limits of the Model Parameters

ICON_L24_Model_Upper_Limit

Diagnostic Upper limits of the model parameters used by the algorithm, as a function of time.

PT12S

unitless

-1000

1000

-999

Altitude of the ICON spacecraft

ICON_L24_Observatory_Altitude

Geodetic altitude (WGS84) of the spacecraft at the time corresponding to the middle of each FUV image, in kilometers.

PT12S

km

0

1000

-999

ICON Spacecraft WGS84 Latitude

ICON_L24_Observatory_Latitude

Geodetic latitude (WGS84) of the spacecraft at the time corresponding to the middle of each FUV image, in degrees.

PT12S

degrees

-90

90

-999

ICON Spacecraft WGS84 Longitude

ICON_L24_Observatory_Longitude

Geodetic longitude (WGS84) of the spacecraft at the time corresponding to the middle of each FUV image, in degrees.

PT12S

degrees

0

360

-999

Initial Guess Disk Short Wave Emission

ICON_L24_Predicted_1356_Disk_Emission

Initial guess short wave disk column emisison rate.

PT12S

Rayleighs

-100

10000000000

-999

Initial Guess Disk Short Wave Emission

ICON_L24_Predicted_LBH_Disk_Emission

Initial guess short wave disk column emisison rate.

PT12S

Rayleighs

-100

10000000000

-999

UTC Time String

ICON_L24_UTC_Time

UTC time corresponding to the retrieved parameters, in string format, as a function of time, in the format: 2017-05-27/00:00:01.435.

PT12S

Bad

Whole Day Retrieval Flags

ICON_L24_Whole_Day_Retrieval_Flag

Single flag set for whole day, where 0 = nominal data set, 1 = whole day skipped because no solar zenith angles were within range.

PT12S

integer

0

1

-999