Earthdata Forum

GES DISC would like to request new science keywords to support new Radio Occultation products.

New science keywords:

EARTH SCIENCE > ATMOSPHERE > RADIO OCCULTATION PROFILES > EXCESS PHASE
EARTH SCIENCE > ATMOSPHERE > RADIO OCCULTATION PROFILES > BENDING ANGLE
EARTH SCIENCE > ATMOSPHERE > RADIO OCCULTATION PROFILES > REFRACTIVITY

Please let me know if you need more information. Thanks!

Thank you for your keyword request. Can you please provide a definition and reference URL for the keywords?

@laurenhb Please see my comment above. Thank You.

Since Radio occultation is tied to a remote sensing technique, have you considered whether these keywords are more appropriate under our 'SPECTRAL/ENGINEERING' keywords? See https://gcmd.earthdata.nasa.gov/KeywordViewer/scheme/all/83150c54-5da8-4ee8-9579-19b95a8dc10c?gtm_keyword=SPECTRAL/ENGINEERING.

@tstevens

Apologies for the delay. The existing keywords that you provided are not well suited for these datasets. Below, I provided more details for the three new science keywords that my team is requesting:


EARTH SCIENCE > ATMOSPHERE > RADIO OCCULTATION PROFILES > EXCESS PHASE

Excess phase quantifies the optical path of a temporally coherent signal as it transects the Earth’s limb less the optical path that would have been obtained by a straight-line vacuum path. Excess phase is induced by refraction of a GNSS signal by the Earth’s atmosphere and ionosphere in GNSS radio occultation. It has the dimension of distance, specifically the temporal refractive delay of a signal multiplied by the speed of light in a vacuum. Its associated independent coordinate is the time of signal reception by a low-Earth orbiting GNSS receiver.

More information:
https://descanso.jpl.nasa.gov/monograph/series6/Chapter_1.pdf
http://tao.cgu.org.tw/index.php/articles/archive/space-science/item/350



EEARTH SCIENCE > ATMOSPHERE > RADIO OCCULTATION PROFILES > BENDING ANGLE

Bending angle quantifies the angle through which a geometric optical ray is bent as it transects the Earth’s atmosphere in limb sounding geometry. It is an intermediate quantity in the processing of GNSS radio occultation measurements. It has the dimension of an angle (radians, degrees, etc.), and its associated independent coordinate is the impact parameter with respect to a local center of curvature of the Earth’s mean sea-level ellipsoid.

More information:
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2001JD900050
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/97JD01569
https://user.eumetsat.int/s3/eup-strapi-media/C3_S_D311b_T2_1_2_D2_2_3_4_5_Radio_Occultation_Level_1b_Bending_Angle_Profiles_FCDR_Product_User_Guide_v1_1_380f7fb7d6.pdf



EARTH SCIENCE > ATMOSPHERE > RADIO OCCULTATION PROFILES > REFRACTIVITY

Refractivity 𝑁 is the index of refraction 𝑛 less unity in parts per million, or 𝑁 = (𝑛 − 1) × 10^6. In GNSS radio occultation, it is retrieved using the Abel transform as applied to profiles of bending angle vs. impact parameter. Its dimension is unitless but typically designated as “N-units”, and its associated independent coordinate is altitude above the mean sea-level geoid.

More information: https://journals.ametsoc.org/view/journals/atot/23/12/jtech1996_1.xml

Thanks,

Lauren

@laurenhb

The new science keywords have been added; please review:

EARTH SCIENCE > ATMOSPHERE > RADIO OCCULTATION PROFILES > EXCESS PHASE: https://cmr.earthdata.nasa.gov/kms/concept/547dd45b-91a6-4511-bdef-157be65d9b6a?format=rdf&version=draft

EARTH SCIENCE > ATMOSPHERE > RADIO OCCULTATION PROFILES > BENDING ANGLE: https://cmr.earthdata.nasa.gov/kms/concept/8fd7f9f6-9b95-4ba4-9df1-7b876b779a86?format=rdf&version=draft

EARTH SCIENCE > ATMOSPHERE > RADIO OCCULTATION PROFILES > REFRACTIVITY: https://cmr.earthdata.nasa.gov/kms/concept/f4ec49af-b1c5-431c-968c-56890da96020?format=rdf&version=draft