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Commit 2d0e1984 authored by David Schäfer's avatar David Schäfer
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Update SoilMoisture.md

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docs/funcs/SoilMoisture.md
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......@@ -88,7 +88,7 @@ soilMoisture_constant(window="12h", thresh=0.0005,
| window | [offset string](docs/ParameterDescriptions.md#offset-strings) | | Minimum duration during which values need to identical to become plateau candidates. See condition (1) |
| thresh | float | `0.0005` | Maximum variance of a group of values to still consider them constant. See condition (2) |
| precipitation_window | [offset string](docs/ParameterDescriptions.md#offset-strings) | `"12h"` | See condition (3) and (4) |
| tolerance | flaot | `0.95` | Tolerance factor, see condition (5) |
| tolerance | float | `0.95` | Tolerance factor, see condition (5) |
| deriv_min | float | `0.0025` | See condition (3) |
| deriv_max | float | `0` | See condition (4) |
| max_missing | integer | `None` | Maximum number of missing values allowed in `window`, by default this condition is ignored |
......@@ -102,11 +102,11 @@ This function flags plateaus/series of constant values in soil moisture data.
The function represents a stricter version of
[constant_varianceBased](docs/funcs/ConstantDetection.md#constants_variancebased).
The additional constraints (3)-(5), are designed to match the special cases of constant
values in soil moisture meassurements and basically for preceeding precipitation events
values in soil moisture measurements and basically for preceding precipitation events
(conditions (3) and (4)) and certain plateau level (condition (5)).
Any set of consecutive values
$`x_k,..., x_{k+n}`$, of a timeseries $`x`$ is flagged, if:
$`x_k,..., x_{k+n}`$, of a time series $`x`$ is flagged, if:
1. $`n > `$`window`
2. $`\sigma(x_k, x_{k+1},..., x_{k+n}) < `$`thresh`
......@@ -133,17 +133,17 @@ soilMoisture_byFrost(soil_temp_variable, window="1h", frost_thresh=0)
| parameter | data type | default value | description |
|--------------------|---------------------------------------------------------------|---------------|---------------------------------------------------------------|
| soil_temp_variable | string | | Name of the soil temperature variable given in the dataset |
| soil_temp_variable | string | | Name of the soil temperature variable in the dataset |
| window | [offset string](docs/ParameterDescriptions.md#offset-strings) | `"1h"` | Window around a value checked for frost events |
| frost_thresh | float | `0` | Soil temperature below `frost_thresh` are considered as frost |
This function flags soil moisture values if the soil temperature
(given in `soil_temp_variable`) drops below `frost_thresh`
within a periode of +/- `window`.
within a period of +/- `window`.
This Function is an implementation of the soil temperature based flagging
as presented in [1] and all default parameter values are taken from this
presented in [1] and all default parameter values are taken from this
publication.
[1] Dorigo, W. et al: Global Automated Quality Control of In Situ Soil Moisture Data
......@@ -154,47 +154,52 @@ publication.
## soilMoisture_byPrecipitation
```
soilMoisture_byPrecipitation(prec_reference, sensor_meas_depth=0,
sensor_accuracy=0, soil_porosity=0,
std_factor=2, std_factor_range="24h"
ignore_missing=False)
soilMoisture_byPrecipitation(prec_variable, sensor_depth=0,
raise_window=None,
sensor_accuracy=0, soil_porosity=0,
std_factor=2, std_window="24h"
ignore_missing=False)
```
| parameter | data type | default value | description |
| ------ | ------ | ------ | ---- |
| prec_reference | string | | A string, denoting the fields name in data, that holds the data series of precipitation values, the to-be-flagged values shall be checked against. |
| sensor_meas_depth | integer | `0` | Depth of the soil moisture sensor in meter.|
| sensor_accuracy | integer | `0` | Soil moisture sensor accuracy in $`\frac{m^3}{m^{-3}}`$ |
| soil_porosity | integer | `0` | Porosoty of the soil, surrounding the soil moisture sensor |
| std_factor | integer | `2` | See condition (2) |
| std_factor_range | string | `"24h"` | See condition (2) |
| ignore_missing | bool | `False` | If True, the variance of condition (2), will also be calculated if there is a value missing in the time window. Selcting Flase (default) results in values that succeed a time window containing a missing value never being flagged (test not applicable rule) |
| parameter | data type | default value | description |
|-----------------|---------------------------------------------------------------|---------------|---------------------------------------------------------------------------|
| prec_variable | string | | Name of the precipitation variable in the dataset |
| raise_window | [offset string](docs/ParameterDescriptions.md#offset-strings) | `None` | Duration during which a rise has to occur |
| sensor_depth | float | `0` | Depth of the soil moisture sensor in meter |
| sensor_accuracy | float | `0` | Soil moisture sensor accuracy in $`\frac{m^3}{m^{-3}}`$ |
| soil_porosity | float | `0` | Porosity of the soil surrounding the soil moisture sensor |
| std_factor | integer | `2` | See condition (2) |
| std_window | [offset string](docs/ParameterDescriptions.md#offset-strings) | `"1h"` | See condition (2) |
| ignore_missing | bool | `False` | Whether to check values even if there is invalid data within `std_window` |
Function flags Soil moisture measurements by flagging moisture rises that do not follow up a sufficient
precipitation event. If measurement depth, sensor accuracy of the soil moisture sensor and the porosity of the
surrounding soil is passed to the function, an inferior level of precipitation, that has to preceed a significant
moisture raise within 24 hours, can be estimated. If those values are not delivered, this inferior bound is set
to zero. In that case, any non zero precipitation count will justify any soil moisture raise.
This function flags rises in soil moisture data if there are no sufficiently large
precipitation events in the preceding 24 hours.
Thus, a data point $`x_k`$ with sampling rate $`f`$ is flagged an invalid soil moisture raise, if:
A data point $`x_k`$ of a time series $`x`$ with sampling rate $`f`$
is flagged, if:
1. The value to be flagged has to signify a rise. This means, for the quotient $`s = `$ (`raise_reference` / $`f`$):
* $`x_k > x_{k-s}`$
2. The rise must be sufficient. Meassured in terms of the standart deviation
$`V`$, of the values in the preceeding `std_factor_range` - window.
This means, with $`h = `$`std_factor_range` / $`f`$:
* $`x_k - x_{k-s} >`$ `std_factor` $`\times V(x_{t-h},...,x_k{k})`$
3. Depending on some sensor specifications, there can be calculated a bound $`>0`$, the rainfall has to exceed to justify the eventual soil moisture raise.
For the series of the precipitation meassurements $`y`$, and the quotient $`j = `$ "24h" / $`f`$, this means:
* $` y_{k-j} + y_{k-j+1} + ... + y_{k} < `$ `sensor_meas_depth` $`\times`$ `sensor_accuracy` $`\times`$ `soil_porosity`
1. $`x_k`$ represents a rise in soil moisture, i.e. for
$`s = `$ (`raise_window` / $`f`$):
$`x_k > x_{k-s}`$
This Function is an implementation of the precipitation based Soil Moisture
flagging, as presented in:
2. The rise is sufficiently large and exceeds a threshold based on the
standard deviation $`\sigma`$ of the values in the preceding `std_window`,
i.e. the following condition is fulfilled for $`h = `$ `std_window` / $`f`$:
Dorigo, W. et al: Global Automated Quality Control of In Situ Soil Moisture Data
from the international Soil Moisture Network. 2013. Vadoze Zone J.
doi:10.2136/vzj2012.0097.
$`x_k - x_{k-s} >`$ `std_factor` $`\cdot \sigma(x_{t-h},...,x_{k})`$
All parameters default to the values, suggested in this publication.
3. The total amount of precipitation within the last 24 hours does not exceed
a certain threshold, i.e. with $`j = `$ "24h" / $`f`$ the following
condition is fulfilled:
$` y_{k-j} + y_{k-j+1} + ... + y_{k} \le `$ `sensor_depth` $`\cdot`$ `sensor_accuracy` $`\cdot`$ `soil_porosity`
This Function is an implementation of the precipitation based flagging
presented in [1] and all default parameter values are taken from this
publication.
[1] Dorigo, W. et al: Global Automated Quality Control of In Situ Soil Moisture Data
from the international Soil Moisture Network. 2013. Vadoze Zone J.
doi:10.2136/vzj2012.0097.
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