Download presentation
Presentation is loading. Please wait.
Published byEverett Marsh Modified over 8 years ago
1
SPM Workshop “Best Practice“, Bruxelles, Feb 23 & 24, 2016 Many-years Observation of Suspended Sediment Concentrations in the German Wadden Sea Rolf Riethmüller and Götz Flöser, Institute of Coastal Research, Helmholtz-Zentrum Geesthacht, Germany
2
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de 2
3
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de 24 samples collector Seapoint Setting Locations positioned at the edge of the gullies (3 m water depth at low water) limited power supply; limited data transmission little need of land-based infrastructure flexibility in choice of operation area operation period March-November (ice-free season) The pile The underwater unit The pole The underwater unit
4
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Data flow: ongoing monitoring and delayed mode quality measures 4 Underwater Unit Data Logger Telemetrie Meteorology GPRS HZG Computer Centre (near) real-time monitoring 10 min median delayed mode processing 10 min median, 2Hz, HADCP profiles HSHS Turbidity East current Water level Maintenance HSHS Turbidity East current Water level Maintenance
5
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Maintenance: cleansing / repairing equipment 5 time schedule: spring/autumn:2 times per month summer:3 to 4 times per month Activities: cleansing repair/exchange equipment take 1 sample after maintenance recover 12 autosampler samples (sometimes) tidal phase: ≈ low (high) water (not always possible) HSHS Turbidity East current Water level
6
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Water sampling methods 6 PumpingSuction sampler Autosampler (pumping, rem. contr.) Vol. 1 dm 3 filling time 1 min Vol. 1 dm 3 filling time 30 sec Vol. 1.25 dm 3 filling time 30 sec well controlledPotential errors: correct timing sampling distance to sensor too early sampling incorrect minutes (e.g. MESZ/UTC) training of hired personell (field & lab work) Potential errors: first bottle filled with stuff from tube bottle swapping training of hired personel (field & lab work)
7
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Relate turbidity to sample SPMC Fit: SPMC Turbi = -16.8+1.95Turbidity Fit: SPMC Turbi =- 0.73+1.44Turbidity (exclud. Autosampler) Hoernum DybJade Bay Turbidity [FTU] SPMC sample [g m -3 ] Turbidity [FTU] Sqrt squared % differences =30% Sqrt squared % differences =23% Ship camp. Maintenance Auto sampler (exclud. Autosampler)
8
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de 8 The need for turbidity sensor intercalibration Use Ship CTD as reference: Scale factor: 0.7 without scale factor with scale factor
9
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Biofouling 1.Increase in Amplitude 2.Max/Min shift in tidal phase 3.No effect in ADV (acoust.) backscatter Maintenancec
10
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de No detectable biofouling effect in ADV (acoust.) backscatter BUT: high variability between optical and acoustical backscatter Turbidity ADV Bsc Biofouling
11
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Approach: select only tidal phases after slack waters and after maintenance: most particles with high settling velocities removed from water column well defined set of fine particles remain in the water column log10(SPMC Turb /g m -3 ) ADV BSC [counts] log10(SPMC Turb /g m -3 ) ADV BSC [counts] Biofouling SPMC
12
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Approach: select only tidal phases after slack waters and after maintenance: Ratio of R = SPMC Turb /SPMC ADV @ slack water will not vary to much Any significant excess over R indicates bio-fouling Biofouling SPMC Turb /SPMC ADV @ slack water Maintenance All Slack R >1 Biofouling – manually flagged Maintenance Turbidity HSHS
13
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Result So far, periods with bio-fouling can be identified by comparison of optical with acoustical backscatter flagged data have to be discarded from further analysis “filling” of data gaps using acoustical backscatter instead seems unlikely so far. Biofouling All “Clean “
14
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Recommendations Main critical points: Pre-operation: Intercalibration of operated sensors (~yearly) Operation: Biofouling – insufficient cleansing due to bad weather; scientifically sub-optimal location of observing system; Post-operation: Thorough delayed mode processing often done to late to identify significant problems in due time Uncertainty estimations bias, random errors of different steps: better term is „degree of consistency“: Samples and turbidity measurements ~30%; samples alone 5 % (SPMC > 50 g m-3) to 30 % (SPMC < 5 g m-3) overall error: yet not determinded; optical turbidity: good guess for random: 30%; bias ????? acoustical Bsc: ???? representativeness / „scale of confidence“: Some campaigns made, but not yet analysed Recommendations for good practice (3 max.): sufficient resources for maintenance, repair and surveys of setting sufficient resources for real-time monitoring and prompt delayed mode processing regular lab calibration and field (water sample) calbration 14
15
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de 15 Fit: SPMC pred =-0.73+1.44Turbidity SPMC sample [g m -3 ] Turbidity [FTU] SPMC Turb [g m -3 ] SPMC ADV [g m -3 ]
16
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de 16 std=46% mean=30%
17
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de 17 std=33% mean=23%
18
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de 18 Recommendations: fast delayed mode processing sampling and concommitant campaings regular (inter)calibration of sensors anti-fouling measures 2 independent parallel measurements
19
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de 19
20
SPM workshop, Bruxelles, Feb 24/25, 2016Rolf Riethmüller rolf.riethmueller@hzg.de Remote sensing: validation of MERIS SPMC-data ESA-algorithm
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.