The Pre-Alpine observatory is the southernmost of the four German TERENO observatories and is operated since 2008 by the Karlsruhe Institute of Technology (KIT) at its Campus Alpin, Institute of Meteorology and Climate Research (IMK-IFU), Garmisch-Partenkirchen (Germany). The TERENO Pre-Alpine Observatory covers parts of the Bavarian Alps (Ammergau Mountains) and their foreland and comprises various measuring sites (including ICOS sites) spanning an elevation from 1600 to 600 m a.s.l. located in the Ammer (709 km²) and Rott (56 km²) catchments. Main land use is forest and grasslands the latter spanning from intensive dairy farming in the forelands to alpine grassing systems in higher elevation. The highest point is at 2185 m a.s.l. in the Ammergau Alps and the outflow is at 533 m a.s.l. Due to the complex topography, the catchment is characterised by large north-south differentiations in soils, land-use and climate. Long-term mean annual precipitation in the northern part is around 1100 mm/a while the southern part with the summits of the Ammer Alps receives more than 2000 mm/a. Maximum precipitation is in summer. The mean annual temperature is around 7-8 °C in the alpine forelands and approx 4-5 °C in the southern mountainous part of the catchment. Its area includes the Hohenpeissenberg and thereby benefits from the long-term hydrometeorological observations of the DWD observatory (since 1781).

Overview of the Pre-Alpine Observatory

TERENO Pre-Alpine observations have been used in conjunction with physically based process models to examine the impacts of land cover–management and climate change on ecosystem-atmosphere cycling of energy (e.g., large-eddy simulation model PALM), water (e.g., WaSiM and GEOtop), as well as C and N (e.g., LandscapeDNDC).

The TERENO Pre-Alpine Observatory is regionally well integrated because it complements networks of the German Weather Service and the Bavarian Environmental Agency. TERENO pre-alpine research is conducted in close cooperation with farmers and other stakeholders (Bavarian State Research Centre for Agriculture) who are interested in climate adapted management strategies.

Reference:

Kiese, R., Fersch B., Baessler C., Brosy C., Butterbach-Bahl K., Chwala C., Dannenmann M.,  Fu J., Gasche R., Grote R., Jahn C., Klatt J., Kunstmann H., Mauder M., Rödiger T., Smiatek G., Soltani M., Steinbrecher R., Völksch I., Werhahn J., Wolf B., Zeeman M., Schmid H.P. (2018). The TERENO-preAlpine Observatory: integrating meteorological, hydrological and biogeochemical measurements and modelling. Vadose Zone Journal. 10.2136/vzj2018.03.0060.

Micrometeorological Instrumentation

EC Station Fendt (Foto: Alexander Krämer WWL)

Eddy-covariance measurements are conducted at the three main grassland sites Graswnag (DE-Gwg), Rottenbuch (DE-RbW) and Fendt (DE-Fen) as well as at a wetland site Schechenfilz (DE-SfN) and forest site Lackenberg (DE-Lkb). In addition to the EC measurement setup (CSAT-3, Campbell Scientific; LI-7500 LI-COR Biosciences), the grassland sites are equipped to observe the full energy balance, including a four-component net radiometer (CNR 4, Kipp & Zonen), self-calibrating soil heat flux plates (HFP01-SC, Hukseflux), soil temperature and soil moisture sensors (T107 and CS616, Campbell Scientific), and basic meteorological instrumentation for measuring mean wind speed and direction, air temperature, relative humidity, air pressure, and precipitation (HMP45 and WXT520, Vaisala). A ceilometer (CL51, Vaisala) is deployed at each of the three sites to determine the height of the atmospheric boundary layer. The TERENO sites  DE-Fen (C1), DE-Gwg (C3), DE SfN (C3) are part of ICOS, a pan-European research infrastructure that provides harmonized and high-precision scientific data on C cycling and GHG budget and perturbations.

Contact: This email address is being protected from spambots. You need JavaScript enabled to view it..

Lysimeter Network

Lysimeter GHG Measuring System Fendt (Foto: Rainer Gasche KIT/IMK-IFU)Lysimeter are installed at the three main grassland sites DE-Gwg, DE-RbW, and DE-Fen. The underlying idea is based on the “space for time” concept which anticipates climatic change over time by a translocation of intact soil–plant mesocosms in space. The main research focus of the lysimeter study in the TERENO Pre-Alpine Observatory is of the impact of climate and management changes on the components of grassland water, C and N cycling and budgets, biosphere–atmosphere–hydrosphere matter exchange (i.e., GHG emissions and leaching), as well as yields and biodiversity. To that end, a total of 36 intact grassland soil cores (area, 1 m2; depth, 1.4 m) were excavated and transferred to lysimeters at DE-Gwg (n = 18), DE-RbW (n = 12), and DE-Fen (n = 6). Six DE-Gwg lysimeters each were transferred to DE-RbW and DE-Fen, and the remaining six were left in DE-Gwg as control . Accordingly, six lysimeters each from DE-RbW were transferred to DE-Fen or remained at DE-RbW. This led to operation of 18 lysimeters at DE-Fen, 12 at DE-RbW, and six at DE-Gwg. Six lysimeters were arranged in a hexagonal structure around one service unit. At each lysimeter station, half of the lysimeters were subject to intensive management and the other half to extensive management following local farmers’ practices.

For each single lysimeter, rates of water balance components (i.e., precipitation, actual evapotranspiration, and seepage water are derived from precision weighing of lysimeters and water tanks. In all lysimeters, volumetric water content and soil temperature are measured at depths of 10, 30, 50, and 140 cm. Soil water is regularly collected by suction cups at the same depths and analyzed for NH₄, NO₃, dissolved organic N, and dissolved organic C. Soil GHG exchange of CO₂, N₂O, and CH₄ is measured by the static chamber approach at DE-Fen, DE-RbW and DE-Gwg by robotic systems that move on rails sequentially from lysimeter to lysimeter and lower a rubber-sealed static dark chamber on top of a collar at each location.

Contact: This email address is being protected from spambots. You need JavaScript enabled to view it., This email address is being protected from spambots. You need JavaScript enabled to view it.

Soil Moisture Network

Since June 2015, spatially distributed measurements of soil moisture, temperature, and matrix potential have been performed at DE-Fen with the wireless underground sensor network SoilNet with 55 measurement profiles distributed over a total area of about 300 by 300 m, with 20 profiles being distributed along a regular 70x70-m grid and 35 profiles being randomly scattered to provide adequate spatial coverage and to facilitate geostatistical analysis of the data. Measurements are performed at depths of 5, 20, and 50 cm in a temporal resolution of 15 min. In addition to soil water potential (MPS-6, Decagon Devices) and water content (SMT100, Truebner GmbH), both sensors record soil temperature.

Contact: This email address is being protected from spambots. You need JavaScript enabled to view it.; This email address is being protected from spambots. You need JavaScript enabled to view it.

Cosmic-Ray Neutron Sensors

From the neutron sensor measurements, soil moisture and snow water variations can be observed within a multihectar footprint size. In TERENO Pre-Alpine, a network of four stationary sensors is operated at DE-Fen, Ach, DE-Gwg, and Esterberg. The site elevations follow a gradient from 600 to 1270 m asl. Each site is equipped with a bare and a moderated CRS-2000B sensor (Hydroinnova Inc.) and an additional measurement device for air pressure (onboard the datalogger), temperature, and humidity (CS215, Campbell). The recording interval for all variables is 10 min and data are transferred by cellular telemetry. The DE-Fen device is situated in the center of soil moisture network.

Contact: This email address is being protected from spambots. You need JavaScript enabled to view it.

Rainfall Observation Using Commercial Microwave Link Networks

Due to the high spatiotemporal variability of precipitation, its accurate estimation is challenging. In particular, in mountainous terrain, rain gauges and weather radars are limited in providing reliable observations. A promising new technique that helps improve rainfall estimation is the use of attenuation data from commercial microwave link (CML) networks, which are used to provide a large part of the backhaul of the cell phone network.To accompany the research on spatially distributed rainfall estimation via CMLs, we have developed a dedicated microwave transmission device to study the relationship between precipitation and microwave propagation in more detail. The system operates two frequencies (22.235 and 34.8 GHz) and two polarizations in parallel, providing the option to analyze differential measurements, which provide more insight into the precipitation drop size distribution and error sources like antenna wetting. Together with two disdrometers, the system is installed at the DE-Fen site.

Contact: This email address is being protected from spambots. You need JavaScript enabled to view it..

Remote Sensing by X-Band Radar

X-Band Radar Geigersau (Foto: KIT/IMK-IFU)Since June 2009, a single polarization X-band rainfall radar (Selex ES GmbH) is operated a 16-m mast at the Geigersau site (955 m asl). Its 90-cm antenna detects the backscatter signals of precipitation at 3° elevation in high temporal and spatial resolution of 12 scans min−1 and 2° by 100-m azimuthal sectors, respectively. Corrected X-band radar rainfall data, with its high spatial-temporal resolution, can improve the skill of hydrological modeling for the Ammer catchment with respect tothe lower resolution RADOLAN data.

Contact: This email address is being protected from spambots. You need JavaScript enabled to view it.

SUSALPS (www.susalps.de)

The aim of the SUSALPS project is to improve our knowledge on the effects of current and future climate and management on ecosystem functions performed by grasslands under given  socio-economic conditions. Based on this improved knowledge, sustainable management options for grasslands in the alps and the foothills of the alps will be developed in close cooperation with stakeholders. SUSALPS is a BMBF funded BonaRes Project jointly conducted by KIT, TUM, HMGU, University Bayreuth and LfL.

ScaleX (https://www.imk-ifu.kit.edu/scalex.php)

The TERENO Pre- Alpine Observatory integrates meteorological, hydrological, and biogeochemical measurements and activities from the atmospheric boundary layer through the atmosphere-ecosystem interface down to the aquifer. In brief, interdisciplinary research in the TERENO Pre-Alpine Observatory spans the variability and interaction of interlinked water, energy and nutrient cycles, including ecosystem C and N dynamics, and associated exchange processes with the atmosphere (greenhouse gases) and hydrosphere (N leaching) and biodiversity. Mountain areas are characterized by steep topographically induced climate gradients, enabling study designs spanning different climatic zones along short distances. In the Ammer catchment region of the observatory, temperature lapse rates are around 0.6°C per 100 m in summer and 0.45°C per 100 m in winter.

The key hydrological objectives comprise (i) improved quantification of the spatiotemporal variability of precipitation in complex terrain, (ii) investigation of soil moisture response to precipitation, and (iii) quantification of the variability, interaction, and closure of the regional interlinked water and energy cycles.

The key micrometeorological objectives are related to the biosphere–atmosphere exchange of heat, water, and CO₂, with particular focus on (i) improving our understanding of atmospheric exchange processes in complex terrain, (ii) investigation of the energy balance closure problem, and (iii) the response of net ecosystem exchange to transient climatic events.

The key biogeochemical objectives include characterization and quantification of ecosystem C and N storage, turnover, and associated biosphere–atmosphere–hydrosphere matter exchange with a particular focus on (i) GHG emissions (CO₂, CH₄, and N₂O), (ii) nutrient export by seepage water, and (iii) vegetation and microbial productivity and diversity affecting ecosystem C and N transformations and losses.