Microwave satellite data to quantify effects of global climate change on arctic rivers

Water Resources Research

et al. 2023

The timing of ice freeze‐up and break‐up in the Arctic may be responding to climate change. Passive microwave remote sensing is a powerful technique for monitoring this timing. We processed low‐frequency microwave time series from the European Space Agency Soil Moisture and Ocean Salinity (SMOS) mission for a set of 31 satellite gauging reaches (SGRs) above 65°N between 2010 and 2020 to determine timing of freeze‐up and break‐up and annual river ice durations. We found indication of progressive ice cover reduction over more than half of the monitored river reaches, with possibly the fastest rate occurring over northeast Russia. Some rivers in high‐latitude North America experienced a slight increase in ice cover. Across the data set, we observed an average 2.2 days shift toward later ice freeze‐up in autumn and an average 0.6 days shift toward earlier ice break‐up in spring, resulting in an average decrease of 3.4 days in ice duration between 2010 and 2020. River reaches with the longest duration of ice cover appeared to have experienced the fastest rate of decrease. A possible reduction of the time lag between air temperature rise or fall and corresponding river ice break‐up and freeze‐up was also observed. Yet results on variability are carefuly interpreted given the short length of the time series (2010–2020) and the low statistical confidence rates calculated for the decadal tendency. Still outcomes are consistent with increases in global and Arctic surface air temperature. Following these time series over the next decade using passive microwave satellite sensors can monitor ice cover duration in the Arctic and will further determine temporal and regional trends.

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Section: Study Areamentioning

confidence: 99%

Section: Tablementioning

confidence: 99%

Section: Satellite Gauging Reaches From Passive Microwave Datamentioning

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Section: Introductionmentioning

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Ice Freeze‐Up and Break‐Up in Arctic Rivers Observed With Satellite L‐Band Passive Microwave Data From 2010 to 2020

Podkowa

Water Resources Research

et al. 2023

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“…Orbital sensors at various spatial resolutions and repeat intervals can be used to observe changes in a (Bjerklie et al, 2003(Bjerklie et al, , 2005Smith, 1997;Smith et al, 1996). To realistically address both global (Milliman et al, 2008) and regional (Hirpa et al, 2013) measurement needs; however, the following are required: (a) sensing with high PMR fits these requirements and, at Ka-band, has been shown to be an efficient technique to monitor rivers using a (Brakenridge et al, 2012;Brakenridge et al, 2007;Brakenridge et al, 2021;Z. Kugler et al, 2010;Z.…”

Section: Choice Of Satellite Sensorsmentioning

confidence: 99%

Passive Microwave Radiometry at Different Frequency Bands for River Discharge Retrievals

Brakenridge

Earth and Space Science

2023

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The present era of climate change and expanding population requires major improvements in sustained observation of global river discharge. Floods and droughts are affecting food supplies, and suspected long‐term trends require appropriate data for evaluation. Orbital remote sensing can address this observational need. Here we use satellite Ka‐ (36.5 GHz) and L‐band (1–2 GHz) passive microwave radiometry (PMR) to monitor river discharge changes and determine what size rivers can be measured and the frequencies and polarization configurations that yield the most robust results. Selected satellite gauging reaches (SGRs) can be measured at near‐daily intervals from 1998 to present (Ka‐band) and 2010 to present (L‐band). The SGRs are 10–36 km in length; the dynamic proportion of water surface area within each varies with river discharge. Due to contrasting dielectric properties, water and land emit different intensities of microwave radiation; thus emission from a mixed water/land pixel decreases as the proportion of water within the pixel increases. Depending on the river and floodplain morphology, water flow area can be a robust indicator of discharge and the microwave sensors can retrieve daily discharge to ±20%. Instead of spatial resolution, it is the sensor measurement precision, geolocation accuracy, and channel and floodplain morphology that most strongly affect accuracy. Calibration of flow area signals to discharge can be performed using nearby ground stations (even if now discontinued) or by comparison to hydrologic modeling.

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Merged AMSR-E/AMSR-2 and GPM Passive Microwave Radiometry for Measuring River Floods, Runoff, and Ice Cover

Brakenridge

Earth Observation for Flood Applications

2021