Satellite microwave assessment of Northern Hemisphere lake ice phenology from 2002 to 2015
A new automated method enabling consistent satellite assessment of seasonal lake ice phenology at 5 km resolution was developed for all lake pixels (water coverage ≥ 90 %) in the Northern Hemisphere using 36.5 GHz H-polarized brightness temperature (<i>T</i><sub>b</sub>) ob...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-01-01
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| Series: | The Cryosphere |
| Online Access: | http://www.the-cryosphere.net/11/47/2017/tc-11-47-2017.pdf |
| Summary: | A new automated method enabling consistent satellite assessment of seasonal
lake ice phenology at 5 km resolution was developed for all lake pixels
(water coverage ≥ 90 %) in the Northern Hemisphere using 36.5 GHz
H-polarized brightness temperature (<i>T</i><sub>b</sub>) observations from the
Advanced Microwave Scanning Radiometer for EOS and Advanced Microwave
Scanning Radiometer 2 (AMSR-E/2) sensors. The lake phenology metrics include
seasonal timing and duration of annual ice cover. A moving <i>t</i> test (MTT)
algorithm allows for automated lake ice retrievals with daily temporal
fidelity and 5 km resolution gridding. The resulting ice phenology record
shows strong agreement with available ground-based observations from the
Global Lake and River Ice Phenology Database (95.4 % temporal agreement)
and favorable correlations (<i>R</i>) with alternative ice phenology records from
the Interactive Multisensor Snow and Ice Mapping System (<i>R</i> = 0.84 for water
clear of ice (WCI) dates; <i>R</i> = 0.41 for complete freeze over (CFO) dates)
and Canadian Ice Service (<i>R</i> = 0.86 for WCI dates; <i>R</i> = 0.69 for CFO
dates). Analysis of the resulting 12-year (2002–2015) AMSR-E/2 ice record
indicates increasingly shorter ice cover duration for 43 out of 71
(60.6 %) Northern Hemisphere lakes examined, with significant
(<i>p</i> < 0.05) regional trends toward earlier ice melting for only five
lakes. Higher-latitude lakes reveal more widespread and larger trends toward
shorter ice cover duration than lower-latitude lakes, consistent with
enhanced polar warming. This study documents a new satellite-based approach
for rapid assessment and regional monitoring of seasonal ice cover changes
over large lakes, with resulting accuracy suitable for global change studies. |
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| ISSN: | 1994-0416 1994-0424 |