26 research outputs found
Arctic Mission Benefit Analysis: impact of sea ice thickness, freeboard, and snow depth products on sea ice forecast performance
Assimilation of remote-sensing products of sea ice thickness (SIT) into sea
ice–ocean models has been shown to improve the quality of sea ice forecasts.
Key open questions are whether assimilation of lower-level data products such
as radar freeboard (RFB) can further improve model performance and what
performance gains can be achieved through joint assimilation of these data
products in combination with a snow depth product. The Arctic Mission Benefit
Analysis system was developed to address this type of question. Using the
quantitative network design (QND) approach, the system can evaluate, in a
mathematically rigorous fashion, the observational constraints imposed by
individual and groups of data products. We demonstrate the approach by
presenting assessments of the observation impact (added value) of different
Earth observation (EO) products in terms of the uncertainty reduction in a
4-week forecast of sea ice volume (SIV) and snow volume (SNV) for three
regions along the Northern Sea Route in May 2015 using a coupled model of the
sea ice–ocean system, specifically the Max Planck Institute Ocean
Model. We assess seven satellite products: three real products and four
hypothetical products. The real products are monthly SIT, sea ice freeboard
(SIFB), and RFB, all derived from CryoSat-2 by the Alfred Wegener Institute.
These are complemented by two hypothetical monthly laser freeboard (LFB)
products with low and high accuracy, as well as two hypothetical monthly snow
depth products with low and high accuracy.On the basis of the per-pixel uncertainty ranges provided with the CryoSat-2
SIT, SIFB, and RFB products, the SIT and RFB achieve a much better
performance for SIV than the SIFB product. For SNV, the performance of SIT is
only low, the performance of SIFB is higher and the performance of RFB is yet
higher. A hypothetical LFB product with low accuracy (20 cm
uncertainty) falls between SIFB and RFB in performance for both SIV and SNV.
A reduction in the uncertainty of the LFB product to 2 cm yields a
significant increase in performance.Combining either of the SIT or freeboard products with a hypothetical
snow depth product achieves a significant performance increase.
The uncertainty in the snow product matters: a higher-accuracy product
achieves an extra performance gain.
Providing spatial and temporal uncertainty correlations with the
EO products would be beneficial not only for QND assessments,
but also for assimilation of the products.</p
Arctic sea ice at 1.5 and 2 °c
This is the author accepted manuscript. The final version is available from Springer Nature via the DOI in this recordIn the Paris Agreement, nations committed to a more ambitious climate policy target, aiming to limit global warming to 1.5 °C rather than 2 °C above pre-industrial levels. Climate models now show that achieving the 1.5 °C goal would make a big difference for Arctic sea ice
Rigorous assessment of mission impact on sea ice forecast quality
We present the prototype of a a flexible modelling system for Arctic Mission Benefit Analysis (ArcMBA) that evaluates in a mathematically rigorous fashion the observational constraints imposed by individual and groups of E0 data products in using the quantitative network design (QND) approach. The assessment of the observation impact (added value) is performed in terms of the uncertainty reduction in a four-week forecast of sea ice and snow volumes (SIV and SNV) for three regions along the Northern Sea Route (NSR) by a coupled model of the sea ice-ocean system, which is extended by observation operators that link the simulated variables to equivalents of sea ice thickness (SIT), sea ice freeboard (SWB), radar freeboard (RFB), laser freeboard (LIB), and snow depth (SND) products