XBT, ARGO Float and Ship-Based CTD Profiles Intercompared under Strict Space-Time Conditions in the Mediterranean Sea: Assessment of Metrological Comparability
Abstract
:1. Introduction
2. Materials and Methods
2.1. XBT vs. Argo Pairing
- ΔLatitude: ±0.10°;
- ΔLongitude: ±0.15°;
- Δtime: ±7 days and ±1 day (nominal intervals);
- Δdepth: ±1 m.
2.1.1. XBT vs. Argo Pairing: Dataset Obtained in the Large Time Window (±7 days)
2.1.2. XBT vs. Argo Pairing: Dataset Obtained in the Strict Time Window (±1 day)
2.2. Argo vs. Ship-Based CTD Pairing
- Year: from 2000 to 2018 (all months and days);
- Longitude range: from 6°W to 36°E;
- Latitude range: from 30°N to 44.5°N;
- Measured variables: t, SP;
- Dataset: CTD, PFL (Argo Profiling Floats).
- no. 5664 CTD casts;
- no. 55,174 Argo casts.
- ΔLatitude: ±0.10°;
- ΔLongitude: ±0.15°;
- Δdepth (for each t and SP values in the matched profiles): ±1 m;
- Δtime: ±1 day.
- Longitude range: from 3.097°E to 32.720°E;
- Latitude range: from 33.563°N to 43.533°N;
- Time period: from the 2nd of April 2006 to the 6th of June 2018;
- no. of profiles matched (Argo vs. CTD): 360;
- no. of Argo individual profiles: 96;
- no. of (ship-based) CTD individual profiles: 135 (for each profile, the CTD type is declared as “unknown” in the WOD database);
- no. of Argo floats involved: 47 (whose subdivision into models is reported in Table 1).
3. Results
3.1. XBT vs. Argo Comparison
3.1.1. XBT vs. Argo Comparison: Results Obtained in the Large Time Window (±7 Days)
3.1.2. XBT vs. Argo Comparison: Results Obtained in the Strict Time Window (±1 Day)
3.1.3. XBT vs. Argo Comparison: A Further Statistical Analysis
3.2. Argo vs. Ship-Based CTD Comparison
- no. of matches with not-adjusted Argo profiles: 199 (with a total number n of matched points equal to 40,571 for both t and SP values);
- no. of matches with adjusted Argo profiles: 161 (with a total number n of matched points equal to 10,455 for both t and SP values).
3.2.1. Argo vs. Ship-Based CTD Comparison: A Further Statistical Analysis
4. Discussion
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Argo Model | # PFL | Argo Model | # PFL |
---|---|---|---|
APEX | 1 | PROVOR | 7 |
ARVOR | 5 | PROVOR CTS2 | 2 |
ARVOR A3 | 1 | PROVOR CTS31-DO | 2 |
ARVOR DO | 2 | PROVOR CTS3-DO | 3 |
ARVOR-I | 2 | PROVOR-II | 1 |
ARVOR-N | 3 | PROVOR-III | 18 |
T-4 & T-6 | T5 | T10 | Deep Blue | |
---|---|---|---|---|
# matched points | 1301 | 2481 | 131 | 11,827 |
Max Δt (°C) | 4.29 | 8.10 | 1.20 | 8.01 |
Min Δt (°C) | −1.09 | −1.65 | −0.60 | −2.31 |
Mean Δt (°C) | 0.11 | 0.13 | 0.33 | 0.10 |
SD (°C) | 0.36 | 0.59 | 0.31 | 0.46 |
Median Δt (°C) | 0.07 | 0.02 | 0.25 | 0.06 |
T-4 & T-6 | T5 | T10 | Deep Blue | |
---|---|---|---|---|
# matched points | 475 | 961 | 100 | 4502 |
Max Δt (°C) | 4.29 | 8.10 | 1.20 | 8.01 |
Min Δt (°C) | −1.09 | −1.65 | −0.60 | −2.31 |
Mean Δt (°C) | 0.21 | 0.31 | 0.36 | 0.19 |
SD (°C) | 0.57 | 0.91 | 0.35 | 0.72 |
Median Δt (°C) | 0.01 | 0.11 | 0.45 | 0.07 |
T-4 & T-6 | T5 | T10 | Deep Blue | |
---|---|---|---|---|
# matched points | 826 | 1520 | 31 | 7325 |
Max Δt (°C) | 0.48 | 0.57 | 0.42 | 0.93 |
Min Δt (°C) | −0.62 | −0.26 | 0.09 | −0.65 |
Mean Δt (°C) | 0.05 | 0.01 | 0.23 | 0.05 |
SD (°C) | 0.12 | 0.12 | 0.08 | 0.12 |
Median Δt (°C) | 0.06 | −0.01 | 0.22 | 0.05 |
T-4 & T-6 | T5 | Deep Blue | |
---|---|---|---|
# matched points | 322 | 475 | 1804 |
Max Δt (°C) | 4.29 | 4.68 | 6.33 |
Min Δt (°C) | −0.43 | −0.84 | −1.55 |
Mean Δt (°C) | 0.12 | 0.09 | 0.13 |
SD (°C) | 0.44 | 0.40 | 0.41 |
Median Δt (°C) | 0.07 | 0.01 | 0.07 |
T-4 & T-6 | T5 | Deep Blue | |
---|---|---|---|
# matched points | 128 | 143 | 635 |
Max Δt (°C) | 4.29 | 4.68 | 6.33 |
Min Δt (°C) | −0.37 | −0.84 | −1.55 |
Mean Δt (°C) | 0.18 | 0.27 | 0.24 |
SD (°C) | 0.68 | 0.69 | 0.67 |
Median Δt (°C) | 0.05 | 0.06 | 0.10 |
Quantity | T-4 & T-6 | T5 | Deep Blue |
---|---|---|---|
# matched points | 194 | 332 | 1169 |
Max Δt (°C) | 0.48 | 0.37 | 0.32 |
Min Δt (°C) | −0.43 | −0.16 | −0.49 |
Mean Δt (°C) | 0.07 | 0.01 | 0.06 |
SD (°C) | 0.11 | 0.10 | 0.10 |
Median Δt (°C) | 0.08 | −0.01 | 0.07 |
Argo Data | Slope b | t-Test |
---|---|---|
not-adj_temp | (−0.6 ± 1.4)E−05 °C/day | NO drift |
yes-adj_temp | (6.2 ± 1.0)E−05 °C/day | YES drift |
not-adj_sal | (21 ± 9)E−06 PSU/day | YES drift |
yes-adj_sal | (29 ± 2)E−06 PSU/day | YES drift |
Inter Comparison | Bias on Water Column | Bias for d > 100 m | ||
---|---|---|---|---|
t / °C | Sp / PSU | t / °C | Sp / PSU | |
XBT vs. Argo | 0.12 ± 0.41 | 0.05 ± 0.10 | ||
Argo vs. CTD | −0.02 ± 0.20 | −0.013 ± 0.041 | −0.02 ± 0.08 | −0.011 ± 0.026 |
Argoadj vs. CTD | 0.00 ± 0.23 | −0.009 ± 0.038 | −0.01 ± 0.06 | −0.009 ± 0.021 |
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Bordone, A.; Pennecchi, F.; Raiteri, G.; Repetti, L.; Reseghetti, F. XBT, ARGO Float and Ship-Based CTD Profiles Intercompared under Strict Space-Time Conditions in the Mediterranean Sea: Assessment of Metrological Comparability. J. Mar. Sci. Eng. 2020, 8, 313. https://doi.org/10.3390/jmse8050313
Bordone A, Pennecchi F, Raiteri G, Repetti L, Reseghetti F. XBT, ARGO Float and Ship-Based CTD Profiles Intercompared under Strict Space-Time Conditions in the Mediterranean Sea: Assessment of Metrological Comparability. Journal of Marine Science and Engineering. 2020; 8(5):313. https://doi.org/10.3390/jmse8050313
Chicago/Turabian StyleBordone, Andrea, Francesca Pennecchi, Giancarlo Raiteri, Luca Repetti, and Franco Reseghetti. 2020. "XBT, ARGO Float and Ship-Based CTD Profiles Intercompared under Strict Space-Time Conditions in the Mediterranean Sea: Assessment of Metrological Comparability" Journal of Marine Science and Engineering 8, no. 5: 313. https://doi.org/10.3390/jmse8050313