A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to Greenland
Surface melt and mass loss of the Greenland Ice Sheet may play crucial roles in global climate change due to their positive feedbacks and large fresh-water storage. With few other regular meteorological observations available in this extreme environment, measurements from automatic weather stations...
Published in: | The Cryosphere |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2016
|
Subjects: | |
Online Access: | https://doi.org/10.5194/tc-10-727-2016 https://doaj.org/article/b61c1d6183a3489999ec1354106296d8 |
id |
ftdoajarticles:oai:doaj.org/article:b61c1d6183a3489999ec1354106296d8 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:b61c1d6183a3489999ec1354106296d8 2023-05-15T16:21:23+02:00 A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to Greenland W. Wang C. S. Zender D. van As P. C. J. P. Smeets M. R. van den Broeke 2016-03-01T00:00:00Z https://doi.org/10.5194/tc-10-727-2016 https://doaj.org/article/b61c1d6183a3489999ec1354106296d8 EN eng Copernicus Publications http://www.the-cryosphere.net/10/727/2016/tc-10-727-2016.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-10-727-2016 https://doaj.org/article/b61c1d6183a3489999ec1354106296d8 The Cryosphere, Vol 10, Iss 2, Pp 727-741 (2016) Environmental sciences GE1-350 Geology QE1-996.5 article 2016 ftdoajarticles https://doi.org/10.5194/tc-10-727-2016 2022-12-31T05:50:54Z Surface melt and mass loss of the Greenland Ice Sheet may play crucial roles in global climate change due to their positive feedbacks and large fresh-water storage. With few other regular meteorological observations available in this extreme environment, measurements from automatic weather stations (AWS) are the primary data source for studying surface energy budgets, and for validating satellite observations and model simulations. Station tilt, due to irregular surface melt, compaction and glacier dynamics, causes considerable biases in the AWS shortwave radiation measurements. In this study, we identify tilt-induced biases in the climatology of surface shortwave radiative flux and albedo, and retrospectively correct these by iterative application of solar geometric principles. We found, over all the AWS from the Greenland Climate Network (GC-Net), the Kangerlussuaq transect (K-transect) and the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) networks, insolation on fewer than 40 % of clear days peaks within ±0.5 h of solar noon time, with the largest shift exceeding 3 h due to tilt. Hourly absolute biases in the magnitude of surface insolation can reach up to 200 W m −2 , with respect to the well-understood clear-day insolation. We estimate the tilt angles and their directions based on the solar geometric relationship between the simulated insolation at a horizontal surface and the observed insolation by these tilted AWS under clear-sky conditions. Our adjustment reduces the root mean square error (RMSE) against references from both satellite observation and reanalysis by 16 W m −2 (24 %), and raises the correlation coefficients with them to above 0.95. Averaged over the whole Greenland Ice Sheet in the melt season, the adjustment in insolation to compensate station tilt is ∼ 11 W m −2 , enough to melt 0.24 m of snow water equivalent. The adjusted diurnal cycles of albedo are smoother, with consistent semi-smiling patterns. The seasonal cycles and inter-annual variabilities of albedo agree better ... Article in Journal/Newspaper glacier Greenland Ice Sheet Kangerlussuaq The Cryosphere Directory of Open Access Journals: DOAJ Articles Greenland Kangerlussuaq ENVELOPE(-55.633,-55.633,72.633,72.633) The Cryosphere 10 2 727 741 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 W. Wang C. S. Zender D. van As P. C. J. P. Smeets M. R. van den Broeke A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to Greenland |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Surface melt and mass loss of the Greenland Ice Sheet may play crucial roles in global climate change due to their positive feedbacks and large fresh-water storage. With few other regular meteorological observations available in this extreme environment, measurements from automatic weather stations (AWS) are the primary data source for studying surface energy budgets, and for validating satellite observations and model simulations. Station tilt, due to irregular surface melt, compaction and glacier dynamics, causes considerable biases in the AWS shortwave radiation measurements. In this study, we identify tilt-induced biases in the climatology of surface shortwave radiative flux and albedo, and retrospectively correct these by iterative application of solar geometric principles. We found, over all the AWS from the Greenland Climate Network (GC-Net), the Kangerlussuaq transect (K-transect) and the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) networks, insolation on fewer than 40 % of clear days peaks within ±0.5 h of solar noon time, with the largest shift exceeding 3 h due to tilt. Hourly absolute biases in the magnitude of surface insolation can reach up to 200 W m −2 , with respect to the well-understood clear-day insolation. We estimate the tilt angles and their directions based on the solar geometric relationship between the simulated insolation at a horizontal surface and the observed insolation by these tilted AWS under clear-sky conditions. Our adjustment reduces the root mean square error (RMSE) against references from both satellite observation and reanalysis by 16 W m −2 (24 %), and raises the correlation coefficients with them to above 0.95. Averaged over the whole Greenland Ice Sheet in the melt season, the adjustment in insolation to compensate station tilt is ∼ 11 W m −2 , enough to melt 0.24 m of snow water equivalent. The adjusted diurnal cycles of albedo are smoother, with consistent semi-smiling patterns. The seasonal cycles and inter-annual variabilities of albedo agree better ... |
format |
Article in Journal/Newspaper |
author |
W. Wang C. S. Zender D. van As P. C. J. P. Smeets M. R. van den Broeke |
author_facet |
W. Wang C. S. Zender D. van As P. C. J. P. Smeets M. R. van den Broeke |
author_sort |
W. Wang |
title |
A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to Greenland |
title_short |
A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to Greenland |
title_full |
A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to Greenland |
title_fullStr |
A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to Greenland |
title_full_unstemmed |
A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to Greenland |
title_sort |
retrospective, iterative, geometry-based (rigb) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: application to greenland |
publisher |
Copernicus Publications |
publishDate |
2016 |
url |
https://doi.org/10.5194/tc-10-727-2016 https://doaj.org/article/b61c1d6183a3489999ec1354106296d8 |
long_lat |
ENVELOPE(-55.633,-55.633,72.633,72.633) |
geographic |
Greenland Kangerlussuaq |
geographic_facet |
Greenland Kangerlussuaq |
genre |
glacier Greenland Ice Sheet Kangerlussuaq The Cryosphere |
genre_facet |
glacier Greenland Ice Sheet Kangerlussuaq The Cryosphere |
op_source |
The Cryosphere, Vol 10, Iss 2, Pp 727-741 (2016) |
op_relation |
http://www.the-cryosphere.net/10/727/2016/tc-10-727-2016.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-10-727-2016 https://doaj.org/article/b61c1d6183a3489999ec1354106296d8 |
op_doi |
https://doi.org/10.5194/tc-10-727-2016 |
container_title |
The Cryosphere |
container_volume |
10 |
container_issue |
2 |
container_start_page |
727 |
op_container_end_page |
741 |
_version_ |
1766009389281443840 |