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GTS Bulletin: ISAH02 HKLP - Observational data (Binary coded) - BUFR (details are described in the abstract)

The ISAH02 TTAAii Data Designators decode as: T1 (I): Observational data (Binary coded) - BUFR T1T2 (IS): Surface/sea level T1T2A1 (ISA): Routinely scheduled observations for distribution from automatic (fixed or mobile) land stations (e.g. 0000, 0100, … or 0220, 0240, 0300, …, or 0715, 0745, ... UTC) A2 (H): 90°E - 0° tropical belt(The bulletin collects reports from stations: HKLP;) (Remarks from Volume-C: XXX)

Model Output Statistics for HEL (12135)

DWD’s fully automatic MOSMIX product optimizes and interprets the forecast calculations of the NWP models ICON (DWD) and IFS (ECMWF), combines these and calculates statistically optimized weather forecasts in terms of point forecasts (PFCs). Thus, statistically corrected, updated forecasts for the next ten days are calculated for about 5400 locations around the world. Most forecasting locations are spread over Germany and Europe. MOSMIX forecasts (PFCs) include nearly all common meteorological parameters measured by weather stations. For further information please refer to: [in German: https://www.dwd.de/DE/leistungen/met_verfahren_mosmix/met_verfahren_mosmix.html ] [in English: https://www.dwd.de/EN/ourservices/met_application_mosmix/met_application_mosmix.html ]

Algal information along a transect at the island of Helgoland in 2005

A sublittoral transect (P3) in the North of Helgoland that had been investigated ~40 years earlier by Lüning (1970) was traversed again. Scuba dives were carried out between 13.07.2005 and 25.08.2005. For each sampling point, time, date and coordinates were given as well as the depth in m mean low water spring tide. 0.25 m² frames were used to obtain the species composition, total fresh mass and total dry mass. In addition, 1 m² frames were used to record the kelp community by counting the individuals and measuring kelp stipe length, kelp blade area, kelp blade fresh mass, kelp age and fresh mass of epiphytes on the kelp stipes. Equal Location IDs represent the same frame.

Net primary production of Laminaria hyperborea along the vertical depth profile based on different diffuse attenuation coefficients

Over the whole water column, daily diffuse attenuation coefficient (Kd in 1/m) values are based on in situ photosynthetically active radiation (PAR) measurements performed in different depths (1.2, 2.9, 4.4, 6.6 m) during summer 2014. PAR for the algae collection depths is calculated based on daily Kd values. Daily net primary production (NPP in g C/m² seafloor/day) for each sampling depth is calculated with in situ vertical profiles based on daily Kd, leaf area index (Pehlke and Bartsch, 2008) and a photosynthetic quotient (PQ) of 1.18 (Miller III et al. 2009). For comparative purposes, daily NPP values were also calculated using the measured maximum and minimum daily Kd and the mean Kd, which were derived from all daily Kd over the entire sampling period.

Measurements of bending properties of kelp, Laminaria hyperborea, Heligoland, Germany

The flexural rigidity and bending modulus of kelp, Laminaria hyperborea, collected at the MarGate area (https://www.awi.de/en/science/special-groups/scientific-diving/margate.html) north of Heligoland, Germany (latitude: 54° 11.700'N, longitude: 7° 52.600'E) was determined from measurements performed at the Alfred Wegener Institute (AWI) Helmholtz Centre for Polar and Marine Research. Scientific divers from the Biological Institute Helgoland, AWI, collected nine kelps (Laminaria hyperborea) from the MarGate area on 21.06.2022. The collected kelps were transported into the laboratory in boxes filled with seawater from the site and stored in laboratory sinks filled with running aerated seawater from the North Sea during the experiments. The measurements were carried out on 23.06.2022, 25.06.2022, and 27.06.2022. They consisted of cutting strips 20 cm in length (L) and 2.5 cm in width (b) from the blades close to the stipe of each kelp. The cut-out strips were towel-dried, and their thickness (t, mm) and weight in grams were measured. The weight in grams was converted to weight per unit area (w, N/m²) to compute the flexural rigidity per unit width (J, Nm). A standard ruler with precision for the nearest millimeter was used to measure the length (L), width (b), and cantilever length (l) of strips. The thickness (t) of the strip was measured with a caliper gauge that measured to the nearest 0.01 millimeter. The weight of the strip was measured by a weighing scale (Sartorius, LE323S), which had a precision of 0.001 grams. The cut-out strips from each kelp form the nine samples tested for the bending properties. Each sample is used to repeat the cantilever test four times, i.e., both sides' ends, as Henry (2014) recommended to improve the accuracy. An apparatus consisting of two planes, one angled at 45° (θ = 45°) and the other parallel to the horizontal, was used for the test. The device was clamped onto a table on the horizontal plane. The experimental protocol consists of laying each strip onto the apparatus with the strip's edge coinciding with the apparatus's angled edge. After that, the strip is slowly moved forward with a ruler, with the ruler's zero coinciding with the strip's edge. This is done until the tip of the strip touches the inclined plane. The horizontal projection of the length of the hanging strip is equal to the distance between the ruler's tip and the apparatus's angle, termed the cantilever length (l). The flexural rigidity per unit width (J, Nm) and the bending modulus (Eb, N/m²) are then calculated with the second moment of area (I, m⁴) as in Henry (2014).

Local adaptation of microscopic stages of North Atlantic Laminaria digitata to high and low temperatures along latitudes: survival, reproduction and growth

To assess the thermal adaptation of microscopic stages of the kelp Laminaria digitata along latitudes, we conducted laboratory experiments on samples from six locations in the NE Atlantic (Spitsbergen (SPT), Tromsø (TRM), Bodø (BOD; all Norway), Helgoland (HLG; Germany), Roscoff (ROS) and Quiberon (QUI; both France)), spanning the species' entire distribution range. In experiment 1, we exposed gametophytes to (sub-) lethal high priming temperatures (20-25°C) for two weeks, followed by two weeks of recovery at 15°C, to observe gametophyte survival and sporophyte formation. In experiment 2, samples were subjected to (sub-) optimal low temperatures (0-15°C) for 21 days, to assess gametophyte survival, sporophyte formation and growth. During the experiments, samples were kept in 15 µmol photons/m²/s white light under a 16:8h light:dark cycle. Prior to the experiments, cultures were stored at 15°C in iron-free ½ Provasoli enriched seawater in 3-4 µmol photons/m²/s red light.

Dataset for estimating the photosynthetic oxygen production of Laminaria hyperborea off the island of Helgoland in summer 2014

The impact of variable underwater photosynthetically active radiation (PAR) and photosynthetic parameters on photosynthetic oxygen production of Laminaria hyperborea off the island of Helgoland (North Sea, Germany) was investigated throughout summer 2014. L. hyperborea was sampled along a depth gradient (0.5, 2, 4, 6 m) and discs from three different blade regions (5, 25 and 50 cm above the stipe-blade transition zone) were set into photosynthesis versus irradiance (PI) curves. After cutting and before the oxygen incubation, maximum quantum yield (Fv/Fm) were measured as a health indicator. PI-curve parameters were normalized to either fresh mass or disc area. Additionally, chlorophyll a content was measured in each disc and normalized to the same two parameters as PI parameters. In situ PAR was measured in different depths (1.2, 2.9, 4.4, 6.6 m) to gain daily diffuse vertical attenuation coefficient (Kd). PAR along the vertical depth profile was calculated and together with PI-curve parameters oxygen production was calculated along the vertical depth profile. Leaf area index (Pehlke and Bartsch, 2008) was used to extrapolate oxygen production rates to seafloor and a photosynthetic quotient (PQ) of 1.18 (Miller III et al., 2009) to convert rates into carbon fixation rates. This net primary production (NPP) was given along the vertical depth profile based on different Kd values (daily Kd, mean Kd, minimum Kd, maximum Kd).

Frequency of algae along a transect at the island of Helgoland in 2005

A sublittoral transect (P3) in the North of Helgoland that had been investigated ~40 years earlier by Lüning (1970) was traversed again. Scuba dives were carried out between 24.06.2005 and 19.08.2005. For each sampling point, time, date and coordinates were given as well as the corrected depth in m mean low water spring tide. Along the transect, substrate and topography were recorded. Relative frequency and cover of 32 species grown attached to the seafloor and cover of 12 epiphytic species were obtained.

Occurrence and cover of algae along a transect at the island of Helgoland in 2005

A sublittoral transect (P3) in the North of Helgoland that had been investigated ~40 years earlier by Lüning (1970) was traversed again. Scuba dives were carried out between 21.04.2005 and 23.06.2005. At different sampling points (Location ID: P1-P44; start with P1 every new day) along the transect, substrate and topography was recorded and every 5m occurrence and the cover was obtained of the dominant brown algae Fucus serratus, Sargassum muticum, Laminaria digitata, L. hyperborea and Saccharina latissima. The occurrence was measured qualitatively as present/absence (1/0) and the cover was estimated semi-quantitative according to the Kautsky scale as 0 for not present to 100 as 100% cover (Kautsky, 1995). Furthermore, the transect was split into different zones (1-7) depending on the algal vegetation according to the master thesis of C. Gehling (2006). For each sampling point, time, date and coordinates were given as well as the corrected depth in m mean low water spring tide.

Depth distribution and biomass of sublittoral seaweeds at the island of Helgoland in 2005

In 2005, the species composition and spatial distribution of the seaweed community were investigated in the frame of diving surveys along a sublittoral transect in the North of Helgoland that had been investigated ~40 years earlier by Lüning (1970). The cover of dominant brown seaweeds, Fucus serratus, Sargassum muticum, Laminaria digitata, L. hyperborea and Saccharina latissima, was semi-quantitatively assessed to define vegetation zones. Within each zone, all macroalgal species were estimated quantitatively in 3 to 6 random 1 m² quadrats. Additionally, a replicated biomass survey was performed at 6 depths (0.5, 2, 4, 6, 8 and 10 m below mean low water spring tide). The survey investigated the occurrence, cover and relative frequency of the algae community and information about fresh mass and dry mass were obtained. For kelps also stipe length, blade area, blade fresh mass, age and fresh mass of epiphytes was recorded.

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