Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach
The surface energy budget (SEB) of polar regions is key to understanding the polar amplification of global climate change and its worldwide consequences. However, despite a growing network of ground-based automatic weather stations that measure the radiative components of the SEB, extensive areas re...
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ftcopernicus:oai:publications.copernicus.org:tc51110 2023-05-15T13:54:27+02:00 Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach Tricht, Kristof Lhermitte, Stef Gorodetskaya, Irina V. Lipzig, Nicole P. M. 2018-09-27 application/pdf https://doi.org/10.5194/tc-10-2379-2016 https://tc.copernicus.org/articles/10/2379/2016/ eng eng doi:10.5194/tc-10-2379-2016 https://tc.copernicus.org/articles/10/2379/2016/ eISSN: 1994-0424 Text 2018 ftcopernicus https://doi.org/10.5194/tc-10-2379-2016 2020-07-20T16:23:58Z The surface energy budget (SEB) of polar regions is key to understanding the polar amplification of global climate change and its worldwide consequences. However, despite a growing network of ground-based automatic weather stations that measure the radiative components of the SEB, extensive areas remain where no ground-based observations are available. Satellite remote sensing has emerged as a potential solution to retrieve components of the SEB over remote areas, with radar and lidar aboard the CloudSat and CALIPSO satellites among the first to enable estimates of surface radiative long-wave (LW) and short-wave (SW) fluxes based on active cloud observations. However, due to the small swath footprints, combined with a return cycle of 16 days, questions arise as to how CloudSat and CALIPSO observations should be optimally sampled in order to retrieve representative fluxes for a given location. Here we present a smart sampling approach to retrieve downwelling surface radiative fluxes from CloudSat and CALIPSO observations for any given land-based point-of-interest (POI) in polar regions. The method comprises a spatial correction that allows the distance between the satellite footprint and the POI to be increased in order to raise the satellite sampling frequency. Sampling frequency is enhanced on average from only two unique satellite overpasses each month for limited-distance sampling < 10 km from the POI, to 35 satellite overpasses for the smart sampling approach. This reduces the root-mean-square errors on monthly mean flux estimates compared to ground-based measurements from 23 to 10 W m −2 (LW) and from 43 to 14 W m −2 (SW). The added value of the smart sampling approach is shown to be largest on finer temporal resolutions, where limited-distance sampling suffers from severely limited sampling frequencies. Finally, the methodology is illustrated for Pine Island Glacier (Antarctica) and the Greenland northern interior. Although few ground-based observations are available for these remote areas, important climatic changes have been recently reported. Using the smart sampling approach, 5-day moving average time series of downwelling LW and SW fluxes are demonstrated. We conclude that the smart sampling approach may help to reduce the observational gaps that remain in polar regions to further refine the quantification of the polar SEB. Text Antarc* Antarctica glacier Greenland Pine Island Pine Island Glacier Copernicus Publications: E-Journals Greenland Pine Island Glacier ENVELOPE(-101.000,-101.000,-75.000,-75.000) The Cryosphere 10 5 2379 2397 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
The surface energy budget (SEB) of polar regions is key to understanding the polar amplification of global climate change and its worldwide consequences. However, despite a growing network of ground-based automatic weather stations that measure the radiative components of the SEB, extensive areas remain where no ground-based observations are available. Satellite remote sensing has emerged as a potential solution to retrieve components of the SEB over remote areas, with radar and lidar aboard the CloudSat and CALIPSO satellites among the first to enable estimates of surface radiative long-wave (LW) and short-wave (SW) fluxes based on active cloud observations. However, due to the small swath footprints, combined with a return cycle of 16 days, questions arise as to how CloudSat and CALIPSO observations should be optimally sampled in order to retrieve representative fluxes for a given location. Here we present a smart sampling approach to retrieve downwelling surface radiative fluxes from CloudSat and CALIPSO observations for any given land-based point-of-interest (POI) in polar regions. The method comprises a spatial correction that allows the distance between the satellite footprint and the POI to be increased in order to raise the satellite sampling frequency. Sampling frequency is enhanced on average from only two unique satellite overpasses each month for limited-distance sampling < 10 km from the POI, to 35 satellite overpasses for the smart sampling approach. This reduces the root-mean-square errors on monthly mean flux estimates compared to ground-based measurements from 23 to 10 W m −2 (LW) and from 43 to 14 W m −2 (SW). The added value of the smart sampling approach is shown to be largest on finer temporal resolutions, where limited-distance sampling suffers from severely limited sampling frequencies. Finally, the methodology is illustrated for Pine Island Glacier (Antarctica) and the Greenland northern interior. Although few ground-based observations are available for these remote areas, important climatic changes have been recently reported. Using the smart sampling approach, 5-day moving average time series of downwelling LW and SW fluxes are demonstrated. We conclude that the smart sampling approach may help to reduce the observational gaps that remain in polar regions to further refine the quantification of the polar SEB. |
format |
Text |
author |
Tricht, Kristof Lhermitte, Stef Gorodetskaya, Irina V. Lipzig, Nicole P. M. |
spellingShingle |
Tricht, Kristof Lhermitte, Stef Gorodetskaya, Irina V. Lipzig, Nicole P. M. Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach |
author_facet |
Tricht, Kristof Lhermitte, Stef Gorodetskaya, Irina V. Lipzig, Nicole P. M. |
author_sort |
Tricht, Kristof |
title |
Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach |
title_short |
Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach |
title_full |
Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach |
title_fullStr |
Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach |
title_full_unstemmed |
Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach |
title_sort |
improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach |
publishDate |
2018 |
url |
https://doi.org/10.5194/tc-10-2379-2016 https://tc.copernicus.org/articles/10/2379/2016/ |
long_lat |
ENVELOPE(-101.000,-101.000,-75.000,-75.000) |
geographic |
Greenland Pine Island Glacier |
geographic_facet |
Greenland Pine Island Glacier |
genre |
Antarc* Antarctica glacier Greenland Pine Island Pine Island Glacier |
genre_facet |
Antarc* Antarctica glacier Greenland Pine Island Pine Island Glacier |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-10-2379-2016 https://tc.copernicus.org/articles/10/2379/2016/ |
op_doi |
https://doi.org/10.5194/tc-10-2379-2016 |
container_title |
The Cryosphere |
container_volume |
10 |
container_issue |
5 |
container_start_page |
2379 |
op_container_end_page |
2397 |
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1766260333676068864 |