Soil moisture data

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Ground measurements of soil moisture available from NVE

Unit: saturation ratio [%] (0,100). Note that the loggers are not calibrated, so absolute values are uncertain.

Observations of snow, soil moisture and soil temperature were provided for validation by the Norwegian Water Resources and Energy Directorate (NVE); Figure \ref{fig:stations}. In total, 12 stations measuring snow water equivalent were chosen, based on data availability for 2014 (blue circles in Figure \ref{fig:stations}a), in addition to four stations measuring soil moisture and soil temperature (brown crosses in Figure \ref{fig:stations}a). Air temperature was also provided by the Norwegian Water Resources and Energy Directorate for the stations measuring soil temperature and soil moisture (Abrahamsvoll, Kise, Groset and Ås), but due to a bias in the temperature at Groset and Ås, we used data from the Norwegian Meteorological Institute -- through Eklima -- at Møsstrond (close to Groset) and Ås. Soil temperature is measured in nine segments in the vertical, 15 cm apart. % at -15, -30, -45, -60, -75, -90, -105 Soil moisture is measured with Time Domain Reflectometry (TDR) in six segments in the vertical for all stations, at -10 cm, -20 cm, -30 cm, -40 cm, -60 cm and -100 cm.

Specifics about the four stations used in Nilsen-Paper IV is found here: [1]


Modelled soil moisture deficit fra SeNorge

Unit: soil moisture deficit [mm], ranging from 0 (wet) to -15 (dry).

A gridded dataset of daily %air temperature, precipitation, snow water equivalent (SWE), runoff and soil moisture deficit meteorological and hydrological variables is available for Norway at 1$\times$1 km horizontal resolution, namely the SeNorge dataset \citep{Beldring-2003, Tveito-2006}. Gridded air temperature and precipitation in SeNorge are interpolated from observations, produced by the Norwegian Meteorological Institute \citep{Tveito-2006}, whereas hydrological variables are modelled using the Gridded Water Balance model (GWB) by NVE %the Norwegian Water Resources and Energy Directorate \citep{Bergstrom95, Beldring-2003}. %Hydrological variables such as evapotranspiration and soil moisture deficit are modelled with the gridded (1$\times$1 km) water balance model (GWB) by the Norwegian Water Resources and Energy Directorate, forced with temperature and precipitation. %soil moisture deficit [in mm] for spatial correlation analyses. %snow water equivalent fields to validate snow simulations in WRF.


%Interpolation with Optimal kriging. %is performed after subtracting a reference level of the variable, which is created by regressing physical characteristics such as latitude, altitude, distance from the coast etc. After interpolation, the reference level is added back to obtain the original physical characteristics. Monthly lapse rates are used to adjust temperature and precipitation to the terrain. Precipitation measurements are corrected for undercatch before gridding. GWB is a conceptual hydrological model calibrated against runoff data. %Thus, the soil depth or root depth is not explicitly represented (til diskusjon). %% %HBV is forced by the interpolated temperature and precipitation to obtain for instance snow water equivalent, runoff and soil moisture \citep{Saloranta2012}. %% Each grid cell may be divided into four land cover classes, of which lake and glacier make up two of the four, while the other twho are various boreal vegetation types (open land, %bog, %(?), Det lå ikke inne i parameterlista %% forest, alpine, heather, bedrock). %% The land cover classes are based on 1:50 000 maps by the Norwegian Mapping Authority, and tree line information from the Norwegian Institute of Bioeconomy Research \citep{Beldring-2003}. % Og rapport 2008-04 og pers comm. Nasjonalatlas for Norge. Tregrensa ble brukt til å justere. % We used air temperature, evapotranspiration (in mm) and soil moisture deficit (in mm) from this dataset to assess the coupling strength in WRF--Noah-MP. Note that SeNorge provides soil moisture \emph{deficit}, in contrast to soil moisture stations and WRF--Noah-MP that use volumetric water content. Soil moisture deficit is a measure of how much water might be retained in the soil before runoff takes place, defined as %the actual water content minus the field capacity the amount of depleted water between the field capacity and the actual water content \citep{Colleuille-2007-IAH}. % Hvordan beregnes det?

%\emph{Flytt til thesis: Evapotranspiration is modelled as a weighted average of the four land cover classes in one grid cell, including actual evapotration and interception (over vegetation), lake evaporation (over lakes), and there is no evapotranspiration over glaciers and snow} \citep{Salthun-1996, Beldring-2003}. \emph{The actual evaporation is limited by soil moisture below a certain threshold (depending on the land cover class), and follows the potential evapotranspiration above the threshold. Potential evapotranspiration is a function of temperature and monthly correction factors for each season, being highest in June and lowest in Nove+D47mber--March} \citep{Engeland-2004}. \emph{Bucket model er en måte å beregne riktig avrenning på. Få med interception og lake evap i methods.} \remove{Skal dette avsnittet være her eller i diskusjonen? Evapotranspiration in SeNorge has been validated against observations in Norway and Sweden by \citet{Engeland-2004}, who found that GWB overestimates evapotranspiration in early summer, because of the seasonal parameterization of evapotranspiration. The observations showed the highest evapotranspiration in August, not in June. Soil moisture in SeNorge has been validated against station observations, and a column soil model, COUP %at Groset by %\citet{Colleuille-Gillebo-2002} \citet{Colleuille-2007-IAH}. %using two different models (GWB and COUP). Soil moisture deficits were overestimated in summer because of too high evapotranspiration, and were underestimated in winter. The groundwater simulations agreed well with observations at two stations (Abrahamsvoll, depicted in Fig 1, and Fana at the western coast) %(for 15. September 2005) \citep{Colleuille-2007-IAH}.}  % Fig3 i IHA-artikkelen viser 15. september 2005; grw og smd, og passer rimelig bra ved alle grunnvannsstasjonene (det er et tjuetalls). Smd er ikke sammenligna med obs. Fig 5 viser tidsserier ved Fana og Abrahamsvoll, men det gjelder jo for en lengre periode. Sletta derfor parentesen. Fana: Jan 2001--dec 2005; Abrah: jan 1981--des 1985.


Modelled soil moisture -- SMOIS -- from WRF

Unit: volumetric water content [%] (0,n), where n is the porosity.

WRF has 2 m fixed soil depth, with the following layers

______________  0 cm
|  Layer 1    |        thickness of layer 1 = 10 cm 
| midpt 5 cm  |        observations from -10 cm correspond to this layer
|_____________| 10 cm
|  Layer 2    |
|             |        thickness of layer 2 = 30 cm
| midpt 25 cm |        observations from -30 cm correspond to this layer 
|             |
|_____________| 40 cm
|  Layer 3    |
|             |        thickness of layer 3 = 60 cm
|             |        observations from -60 cm correspond to this layer
| midpt 70 cm |
|             |
|             |
|_____________| 100 cm
|  Layer 4    |
|             |        thickness of layer 4 = 100 cm
|             |        observations from -100 cm correspond to this layer
|             |
| midpt 150 cm|
|             |
|             |
|             |
|             |
|             |
|             |
|_____________| 200 cm

Satellite measurements

Soil moisture measurements are available through NASA's Earth Observatory

https://earthdata.nasa.gov/data/standards-and-references/earth-D74data-science-disciplines/land/soil-moisture