Kansas Real-Time Water Quality

USGS station:	Go to NWISWeb
Constituent:
Time period:
Model Form:

Model Form #3

NO3 = 0.532 + 0.00037 SC + 0.0265 sin(2π D) + 0.538 cos(2π D)

where:

NO3 is computed diss. nitrate, in milligrams per liter as nitrogen
SC is specific conductance at 25 degrees Celsius, in microsiemens per centimeter
D is day of year, in the range of integers 1 through 365

Model Archive Summary

The model archive summary for computed diss. nitrate can be viewed in pdf form here.

Model Calibration

Basic Data

Number of measurements:	109
Mean squared error:	0.08684809
Multiple R²:	0.58
Bias correction (smearing) factor:	1

Explanatory Variables

Variable	Value	Standard error
Intercept	0.532	0.0876
SC	0.00037	0.0000857
sin(2π D)	0.0265	0.03955
cos(2π D)	0.538	0.05703

Correlation Matrix

A correlation matrix is not available for this model. Therefore, the prediction interval was calculated by assuming that there is no correlation between the explanatory variables.

Notes

Model derived using Tobit regression estimation (absolute maximum likelihood estimation) approach. Regression models were updated in Kramer and others (2021) and the newest version of the model was applied beginning January 1, 2017. Computations using the previous version of the model (Stone and others, 2012) ended in 2016. More information detailing models, period of application, and computed concentrations can be found in Kramer and others (2021).