1 / 17

Arctic SST Algorithms

Arctic SST Algorithms. Validation of 6 operational SST products in Arctic High latitude algorithm developments (CCI round robin ) Validation of CCI products Conclusions /Challenges F uture work. Arctic conditions. Arctic Ocean is a challenging region for SST:

anakin
Download Presentation

Arctic SST Algorithms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Arctic SST Algorithms • Validation of 6 operational SST products in Arctic • High latitudealgorithmdevelopments (CCI roundrobin) • Validation of CCI products • Conclusions/Challenges • Future work

  2. Arctic conditions • Arctic Ocean is a challenging region for SST: • Persistent cloudiness • Sea Ice • Complex atmosphere • Few in situ data • Extended periods with twilight, day and night only • -> These issues make SST retrievals challenging

  3. Validation of operational products

  4. In situ coverage • Majority of validationresults from Nordic Seas and Barentssea • I.e. Validationresults NOT representative of innerArctic • In situcoverage from Høyer et al, 2012

  5. Validation results • 6 operational products • Solar elevation angles with AATSR, Metop-A and AMSR-E

  6. High latitude algorithms within CCI

  7. Regional vs global coefficients, Arctic Ocean • Daytime : NLSST • Nighttime: SST_3.7 • Sensors: NOAA 17, 18, 19 and Metop-A (2006-2010) • Results from independent test data set. • NOAA-19 has much fewer match-ups than others. • Largest improvements for daytime algorithms • Reduced regional bias in most cases compared to global algorithms

  8. Atmospheric temperature effects • Arctic Ocean • Much more temperature inversions in Arctic compared to Southern Ocean. • Tinv = (Tair_900 – Tair_surf) correlated with SST error • Southern Ocean

  9. Atmospheric profiles • High variability in Arctic associated with anomalous atmospheric profiles, not the case in the Southern Ocean • Both for negative and positive outliers Good (blue) : < -+0.5*RMS Bad (red) : > -+2*RMS Tair_900 - Tair_surf

  10. CCI product validation for high latitudes

  11. High latitude validation results • L2 and L3U products validated • Arctic > 60 deg N • Southern Ocean < 50 deg S • Limited data available for several sensors Spatial coverage, AVHRR-12 + 17 Number of Match-ups

  12. Overall results • Satellite – in situ • Median and stddev • Generally small biases • Significant negative bias for AVHRR 18 • Larger stddev in Arctic than Southern Ocean Timeline of match-ups

  13. Solar zenith angle dependency • AATSR dependence upon water vapour and solar zenith angle • Cold summer bias for AVHRRs

  14. TCWV dependency • AATSR dependence upon water vapour and solar zenith angle • Cold summer bias for AVHRRs

  15. Summary/Challenges • SST products (AATSR, AVHRRs and AMSR-E) have in general larger errors in the Arctic, compared to Global and Southern Ocean performance • Biases generally depend upon Solar Zenith angle and TCWV • AVHRR biases found in operational products as well as ESA CCI products • Regional AVHRR coefficients can improve biases, largest improvements in daytime algorithms. • Limited in ”reference” situ observations in inner Arctic • Arctic NWP profiles with ”large SST errors” are more humid and warmer than profiles from ”low SST errors”

  16. Future work • Continue the validation and errorcharacterisation of Arctic SST products. • Write up the paper on CCI highlatitudealgorithms • Collect in situ data set for highArcticvalidation • Look for alternative SST products: • Develop MW OE Sea Ice and SST processor for AMSR-E and AMSR2 • Develop and validateMetop-A SST + IST product

  17. High latitude DMI-ISAR deployments • 7 week deployed at ODEN icebreaker • Autonomous deployment July-November 2013 • Planned • Activ circumpolar expedition (2014, 2015) • RAL line, Denmark-Greenland

More Related