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<!DOCTYPE html>
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<link rel="stylesheet" type="text/css" href="sst_review_style.css">
<title>Other relevant errors</title>
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<p></p>
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<p><a href="3.2.3.html">Previous - Summary of Individual Observational Errors</a> <a href="index.html">Index</a> <a href="3.3.html">Next - Pervasive Systematic Errors and Biases</a></p>
<h1>Errors in variables other than SST</h1>
<p>
Uncertainties in marine reports in variables other than SST can also be important. For example, even if the measured SST
is "correct", a mis-reported location will cause an apparent error in the SST. Locations and times of reports may
be incorrect for a number of reasons.
</p><p>
Location errors - imprecise locations, locations provided to limited resolution. In some cases, latitude and longitude
are given in ICOADS to a lower resolution than can be coded e.g. 0.1 degree or even 0.5 degrees. This naturally
introduces errors, potentially significant, into the geolocation of marine reports. In areas where SST gradients
are high, this can lead to significant errors in the estimated SST and any other derived values such as anomalies.
</p><p>
In early reports, position was estimated by dead reckoning between more accurate, but less frequent positional fixes.
This can be seen in some early reports as periodic "jumps" in ship location from the accumulated error in the dead
reckoned position to the more certain position. Dai et al. [2019] analysed a year of data (1885) for a subset of ships
and found uncertainties in latitude and longitude of 0.20deg and 0.29deg respectively. This translated to an
uncertainty in the measured SST of around 0.1K to more than 1K in regions of high SST variability.
</p><p>
Time errors - measurements made at a time other than that reported. lag in recording of temperature e.g using a previously
recorded temperature to fill out the log. where through hull sensors used, there can be a lag owing to the thermal
inertia of the hull.
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