Academic Journal
How to reduce sampling errors in spaceborne cloud radar-based snowfall estimates.
| Τίτλος: | How to reduce sampling errors in spaceborne cloud radar-based snowfall estimates. |
|---|---|
| Συγγραφείς: | Scarsi, Filippo Emilio1,2 (AUTHOR) filippo.scarsi@polito.it, Battaglia, Alessandro2,3 (AUTHOR), Maahn, Maximilian4 (AUTHOR), Lhermitte, Stef5,6 (AUTHOR) |
| Πηγή: | Cryosphere. 2025, Vol. 19 Issue 10, p4875-4892. 18p. |
| Θεματικοί όροι: | *Space-based radar, *Sampling errors, *Doppler radar, *Ice sheets, *Meteorological precipitation, *Ice crystals, *Climate change |
| Γεωγραφικοί όροι: | Antarctica |
| Εταιρία/Οντότητα: | United States. National Aeronautics & Space Administration |
| Περίληψη: | Snowfall is an important climate change indicator affecting surface albedo, glaciers, sea ice, freshwater storage, cloud lifetime, and ecosystems. Precise snowfall measurements at high latitudes are particularly important for the estimation of the mass balance of ice sheets; however, the snowfall is difficult to quantify with in situ measurements in those locations. In this context, spaceborne radar and radiometer atmospheric missions can help in the assessment of snowfall at high latitudes. The decommissioned NASA CloudSat mission provided invaluable information about global snowfall climatology from 2006 to 2023. The CloudSat-based estimates of global snowfall are considered the reference for global snowfall estimates, but these data suffer from poor sampling and the inability to see shallow or retrieve heavy precipitation, which limits their use, for example, as input to surface mass balance models of the major ice sheets. WIVERN (WInd VElocity Radar Nephoscope), one of the ESA Earth Explorer 11 selected missions, is equipped with a conical scanning 94 GHz Doppler radar and a passive 94 GHz radiometer, with the main objective of measuring global in-cloud horizontal winds, but also quantifying cloud ice water content and precipitation rate. Its conically scanning system, with a 42° incidence angle, is expected to reduce the radar blind zone near the surface (especially over the ocean) and allows the mission to have a swath width of 800 km and 70 times more sampled points than a fixed-looking instrument. The proposed radar measurements tackle the current uncertainties in snowfall estimates, highly improving the sampling frequency and accuracy of snowfall measurements. The uncertainty in snowfall measurements arises from various factors, including the diurnal cycle, uncertainty in the Z – S relationship, and the sampling error. This study quantifies each of these contributors individually and demonstrates the improved sampling capabilities of the WIVERN conically scanning geometry for some specific regions (Antarctica, Greenland) by computing the sampling error at different spatial and temporal scales via simulations of WIVERN vs. CloudSat orbits and scanning geometry, based on the snowfall rates produced by ERA5 reanalysis. Results show that a WIVERN-like conically scanning system significantly reduces the uncertainty in polar snowfall estimates if compared to a CloudSat-like near-nadir fixed viewing geometry. While CloudSat generates acceptable errors at the annual zonal scales, WIVERN can produce estimates within the climatological variability for latitude–longitude domain larger than 0.5° × 0.5° already at the monthly timescale, making it a valuable product for regional climate model evaluation and as an input to surface mass balance models of the major ice sheets and glaciers. [ABSTRACT FROM AUTHOR] |
| Βάση Δεδομένων: | Academic Search Index |
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| Items | – Name: Title Label: Title Group: Ti Data: How to reduce sampling errors in spaceborne cloud radar-based snowfall estimates. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Scarsi%2C+Filippo Emilio%22">Scarsi, Filippo Emilio</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<i> filippo.scarsi@polito.it</i><br /><searchLink fieldCode="AR" term="%22Battaglia%2C+Alessandro%22">Battaglia, Alessandro</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Maahn%2C+Maximilian%22">Maahn, Maximilian</searchLink><relatesTo>4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Lhermitte%2C+Stef%22">Lhermitte, Stef</searchLink><relatesTo>5,6</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Cryosphere%22">Cryosphere</searchLink>. 2025, Vol. 19 Issue 10, p4875-4892. 18p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Space-based+radar%22">Space-based radar</searchLink><br />*<searchLink fieldCode="DE" term="%22Sampling+errors%22">Sampling errors</searchLink><br />*<searchLink fieldCode="DE" term="%22Doppler+radar%22">Doppler radar</searchLink><br />*<searchLink fieldCode="DE" term="%22Ice+sheets%22">Ice sheets</searchLink><br />*<searchLink fieldCode="DE" term="%22Meteorological+precipitation%22">Meteorological precipitation</searchLink><br />*<searchLink fieldCode="DE" term="%22Ice+crystals%22">Ice crystals</searchLink><br />*<searchLink fieldCode="DE" term="%22Climate+change%22">Climate change</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Antarctica%22">Antarctica</searchLink> – Name: SubjectCompany Label: Company/Entity Group: Su Data: <searchLink fieldCode="DE" term="%22United+States%2E+National+Aeronautics+%26+Space+Administration%22">United States. National Aeronautics & Space Administration</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Snowfall is an important climate change indicator affecting surface albedo, glaciers, sea ice, freshwater storage, cloud lifetime, and ecosystems. Precise snowfall measurements at high latitudes are particularly important for the estimation of the mass balance of ice sheets; however, the snowfall is difficult to quantify with in situ measurements in those locations. In this context, spaceborne radar and radiometer atmospheric missions can help in the assessment of snowfall at high latitudes. The decommissioned NASA CloudSat mission provided invaluable information about global snowfall climatology from 2006 to 2023. The CloudSat-based estimates of global snowfall are considered the reference for global snowfall estimates, but these data suffer from poor sampling and the inability to see shallow or retrieve heavy precipitation, which limits their use, for example, as input to surface mass balance models of the major ice sheets. WIVERN (WInd VElocity Radar Nephoscope), one of the ESA Earth Explorer 11 selected missions, is equipped with a conical scanning 94 GHz Doppler radar and a passive 94 GHz radiometer, with the main objective of measuring global in-cloud horizontal winds, but also quantifying cloud ice water content and precipitation rate. Its conically scanning system, with a 42° incidence angle, is expected to reduce the radar blind zone near the surface (especially over the ocean) and allows the mission to have a swath width of 800 km and 70 times more sampled points than a fixed-looking instrument. The proposed radar measurements tackle the current uncertainties in snowfall estimates, highly improving the sampling frequency and accuracy of snowfall measurements. The uncertainty in snowfall measurements arises from various factors, including the diurnal cycle, uncertainty in the Z – S relationship, and the sampling error. This study quantifies each of these contributors individually and demonstrates the improved sampling capabilities of the WIVERN conically scanning geometry for some specific regions (Antarctica, Greenland) by computing the sampling error at different spatial and temporal scales via simulations of WIVERN vs. CloudSat orbits and scanning geometry, based on the snowfall rates produced by ERA5 reanalysis. Results show that a WIVERN-like conically scanning system significantly reduces the uncertainty in polar snowfall estimates if compared to a CloudSat-like near-nadir fixed viewing geometry. While CloudSat generates acceptable errors at the annual zonal scales, WIVERN can produce estimates within the climatological variability for latitude–longitude domain larger than 0.5° × 0.5° already at the monthly timescale, making it a valuable product for regional climate model evaluation and as an input to surface mass balance models of the major ice sheets and glaciers. [ABSTRACT FROM AUTHOR] |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.5194/tc-19-4875-2025 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 18 StartPage: 4875 Subjects: – SubjectFull: Antarctica Type: general – SubjectFull: United States. National Aeronautics & Space Administration Type: general – SubjectFull: Space-based radar Type: general – SubjectFull: Sampling errors Type: general – SubjectFull: Doppler radar Type: general – SubjectFull: Ice sheets Type: general – SubjectFull: Meteorological precipitation Type: general – SubjectFull: Ice crystals Type: general – SubjectFull: Climate change Type: general Titles: – TitleFull: How to reduce sampling errors in spaceborne cloud radar-based snowfall estimates. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Scarsi, Filippo Emilio – PersonEntity: Name: NameFull: Battaglia, Alessandro – PersonEntity: Name: NameFull: Maahn, Maximilian – PersonEntity: Name: NameFull: Lhermitte, Stef IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 10 Text: 2025 Type: published Y: 2025 Identifiers: – Type: issn-print Value: 19940416 Numbering: – Type: volume Value: 19 – Type: issue Value: 10 Titles: – TitleFull: Cryosphere Type: main |
| ResultId | 1 |