Snow density and ground permittivity retrieved from L-band radiometry: Application to experimental data

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Abstract. The objective of the Nordic Snow Radar Experiment (NoSREx) campaign was to provide a continuous time series of active and passive microwave observations of snow cover at a representative location of the Arctic boreal forest area, covering a whole winter season. The activity was a part of Phase A studies for the ESA Earth Explorer 7 candidate mission CoReH2O (Cold Regions Hydrology Highresolution Observatory).The NoSREx campaign, conducted at the Finnish Meteorological Institute Arctic Research Centre (FMI-ARC) in Sodankylä, Finland, hosted a frequency scanning scatterometer operating at frequencies from X-to Ku-band. The radar observations were complemented by a microwave dualpolarization radiometer system operating from X-to Wbands. In situ measurements consisted of manual snow pit measurements at the main test site as well as extensive automated measurements on snow, ground and meteorological parameters.This study provides a summary of the obtained data, detailing measurement protocols for each microwave instrument and in situ reference data. A first analysis of the microwave signatures against snow parameters is given, also comparing observed radar backscattering and microwave emission to predictions of an active/passive forward model.All data, including the raw data observations, are available for research purposes through the European Space Agency and the Finnish Meteorological Institute. A consolidated dataset of observations, comprising the key microwave and in situ observations, is provided through the ESA campaign data portal to enable easy access to the data.

Section: Measurement Locationmentioning

confidence: 99%

Nordic Snow Radar Experiment

Lemmetyinen

Kontu

Pulliainen

et al. 2016

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“…Snow pit data were used in the development and validation of a new method to measure SWE by differential interferometry (Leinss et al, 2015) and a new ground-snow radiative transfer model at L-band . They were also applied in the monitoring of soil processes (Rautiainen et al, 2012), in the retrieval of snow density and ground permittivity from L-band radiometry (Lemmetyinen et al, 2016a) and in the study of seasonally and spatially varying snow cover brightness temperature . Cheng et al (2014) applied lake ice measurements to validate buoy-based measurements of lake snow and ice thicknesses.…”

Section: Leppänen Et Al: Sodankylä Manual Snow Survey Programmentioning

confidence: 99%

Sodankylä manual snow survey program

Leppänen

Kontu

Hannula

et al. 2016

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Abstract. The manual snow survey program of the Arctic Research Centre of the Finnish Meteorological Institute (FMI-ARC) consists of numerous observations of natural seasonal taiga snowpack in Sodankylä, northern Finland. The easily accessible measurement areas represent the typical forest and soil types in the boreal forest zone. Systematic snow measurements began in 1909 with snow depth (HS) and snow water equivalent (SWE). In 2006 the manual snow survey program expanded to cover snow macro-and microstructure from regular snow pits at several sites using both traditional and novel measurement techniques. Present-day snow pit measurements include observations of HS, SWE, temperature, density, stratigraphy, grain size, specific surface area (SSA) and liquid water content (LWC). Regular snow pit measurements are performed weekly during the snow season. Extensive time series of manual snow measurements are important for the monitoring of temporal and spatial changes in seasonal snowpack. This snow survey program is an excellent base for the future research of snow properties.

“…6 left) with ambient and warm targets and 1.5 K (Fig. 6 right) with sky measurements from both the Kernen and Kenaston sites (T Bsky ≈ 5 K from Lemmetyinen et al, 2016;Pellarin et al, 2016;Le Vine et al, 2005). The biases are lower than 0.3 K. For black body targets, only one point gives errors higher than 3 K. This single occurrence is likely associated with an error in recording the black body physical temperature during the stabilitycheck.…”

Section: Radiometer Calibration Results and Instrument Stability Evalmentioning

confidence: 94%

“…A three-point calibration procedure using the sky, ambient, and heated warm targets was developed to account for the radiometer's calibration nonlinearity and improve the accuracy over the full range of measured T B . The reference sky T B at L-band was considered to be ≈ 5 K for both polarizations based on previously published data from both measured and modelled sources (Pellarin et al, 2016;Lemmetyinen et al, 2016;Le Vine et al, 2005;Delahaye et al, 2002).…”

Section: Calibration Measurement Procedure/post-processingmentioning

confidence: 99%

“…The NASA Aquarius instrument on board the Argentine SAC-D spacecraft acquired L-band observations between September 2012 to July 2015 (Lagerloef et al, 2013), and the NASA Soil Moisture Active Passive (SMAP) satellite was launched in January 2015 (Entekhabi et al, 2015). In addition to monitoring soil moisture and sea surface salinity, these missions also provide useful measurements for cryospheric applications including monitoring the freeze-thaw state of the land surface (Rautiainen et al, , 2014Roy et al, 2015), estimating snow density and ground permittivity (Schwank et al, 2015;Lemmetyinen et al, 2016), and retrieving the thickness of thin sea ice (Kaleschke et al, 2016(Kaleschke et al, , 2012.…”

Section: Introductionmentioning

confidence: 99%

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Radio-frequency interference mitigating hyperspectral L-band radiometer

Toose

Roy

Solheim³

et al. 2017

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Abstract. Radio-frequency interference (RFI) can significantly contaminate the measured radiometric signal of current spaceborne L-band passive microwave radiometers. These spaceborne radiometers operate within the protected passive remote sensing and radio-astronomy frequency allocation of 1400-1427 MHz but nonetheless are still subjected to frequent RFI intrusions. We present a unique surfacebased and airborne hyperspectral 385 channel, dual polarization, L-band Fourier transform, RFI-detecting radiometer designed with a frequency range from 1400 through ≈ 1550 MHz. The extended frequency range was intended to increase the likelihood of detecting adjacent RFI-free channels to increase the signal, and therefore the thermal resolution, of the radiometer instrument. The external instrument calibration uses three targets (sky, ambient, and warm), and validation from independent stability measurements shows a mean absolute error (MAE) of 1.0 K for ambient and warm targets and 1.5 K for sky. A simple but effective RFI removal method which exploits the large number of frequency channels is also described. This method separates the desired thermal emission from RFI intrusions and was evaluated with synthetic microwave spectra generated using a Monte Carlo approach and validated with surface-based and airborne experimental measurements.