Adjustments to LOBO data

It is occassionally necessary to correct data observed with LOBO sensors for obvious problems, such as sensor drift.

These corrections are documented here.

LOBO L02 nitrate concentrations from Oct. 6, 2006 to June 17, 2008. The ISUS sensor was deployed on Oct. 6, 2006 and it was recovered and recalibrated on June 17, 2008. After recalibration, nitrate concentrations computed from the in situ data dropped by 12 micromolar. Comparisons with laboratory measurements also suggest the data latter in the record were too high. The nitrate data were, therefore, adjusted with a linear drift correction of 7 uM/y (12 uM/1.7 y) that was applied beginning on Oct. 6, 2006. The adjusted data were loaded into LOBOViz on June 19, 2008. LOBO M2 nitrate concentrations from 4/11/2008 to June 23, 2008. The calibration file for the ISUS deployed on M2, when the mooring was redeployed on 4/11, has been revised. All data have been recalculated with the new calibration file. LOBO M2 nitrate concentrations from 4/1/2010 to6/27/2011. The ISUS nitrate data drifted continuously to negative values, reaching values near -20 uM on 5/23/2011. The data were reprocessed using the algorithm in Sakamoto et al. (2009) and this eliminated the drift.

Comments to johnson@mbari.org