Meteorologie Consult (Germany)

<strong class="journal-contentHeaderColor">Abstract.</strong> We present an updated version of the BROOK90 hydrological model (B90), which integrates a closed energy and water balance on subdaily time scales. This updated version refines the time-discrete, physically based representations of soil evaporation, interception and transpiration, while also improving the simulation of snowmelt processes on vegetated surfaces. Additionally, the model includes the capability to simulate the sensible heat flux, thereby providing a comprehensive description of the energy balance in conjunction with the water balance for vegetated surfaces. The model was validated using ICOS eddy-covariance measurements from a mature spruce forest at the Anchor Station Tharandt (DE-Tha) in Germany. The subdaily B90 model demonstrates a good agreement with observed 30-minute latent and sensible heat fluxes for dry surfaces, while its performance is less accurate for wet surfaces. Notably, this new version of B90 does not require recalibration; parameter sets from earlier versions remain applicable. The model is well-suited for sampling intervals from 8 hours to 1 minute, depending on the availability and resolution of the input forcing data. It can be effectively used for various purposes, such as validating flux measurements, gap-filling latent and sensible heat flux data, and performing plausibility checks. However, its primary application is in the study of subdaily water balance dynamics, including processes like dew formation, interception, and fog deposition, which are typically not captured in many other daily-scaled water balance models.

Abstract. We present an updated version of the BROOK90 hydrological model (B90), which integrates a closed energy and water balance on subdaily time scales. This updated version refines the time-discrete, physically based representations of soil evaporation, interception and transpiration, while also improving the simulation of snowmelt processes on vegetated surfaces. Additionally, the model includes the capability to simulate the sensible heat flux, thereby providing a comprehensive description of the energy balance in conjunction with the water balance for vegetated surfaces. The model was validated using ICOS eddy-covariance measurements from a mature spruce forest at the Anchor Station Tharandt (DE-Tha) in Germany. The subdaily B90 model demonstrates a good agreement with observed 30-minute latent and sensible heat fluxes for dry surfaces, while its performance is less accurate for wet surfaces. Notably, this new version of B90 does not require recalibration; parameter sets from earlier versions remain applicable. The model is well-suited for sampling intervals from 8 hours to 1 minute, depending on the availability and resolution of the input forcing data. It can be effectively used for various purposes, such as validating flux measurements, gap-filling latent and sensible heat flux data, and performing plausibility checks. However, its primary application is in the study of subdaily water balance dynamics, including processes like dew formation, interception, and fog deposition, which are typically not captured in many other daily-scaled water balance models.

Abstract Water distribution networks are critical infrastructures that should ensure the reliable supply of high quality potable water to its users. Numerical models of these networks are generally governed by many parameters for which the exact value is not known. This may be due to a lack of precise knowledge like for consumer demand or due to a lack of accessibility as for the pipe roughness. For network managers, the effect of these uncertainties on the network state is important information that supports them in the decision-making process. This effect is generally evaluated by propagating the uncertainties using the mathematical model. In the past, perturbation, fuzzy and stochastic collocation methods have been used for uncertainty propagation. However, these methods are limited either in the accuracy of the results or the computational effort of the necessary calculations. This paper uses an alternative spectral approach that uses the polynomial chaos expansion and has the potential to give results of comparable accuracy to the Monte Carlo sampling through the definition of a stochastic model. This approach is applied to the hydraulic model of two real networks in order to evaluate the influence of uncertain demands on the water age.

The characterization of a charged-coupled device (CCD) spectrograph developed at the Laboratory of Atmospheric Physics, Thessaloniki is presented. The absolute sensitivity of the instrument for direct irradiance and sky radiance measurements was determined, respectively, with an uncertainty of 4.4% and 6.6% in the UV-B, and 3% and 6% in the UV-A, visible and near-infrared (NIR) wavelength ranges. The overall uncertainty associated with the direct irradiance and the sky radiance measurements is, respectively, of the order of 5% and 7% in the UV-B, increasing to 10% for low signals [e.g., at solar zenith angles (SZAs) larger than 70 degrees ], and 4% and 6% in the UV-A, visible, and NIR. Direct solar spectral irradiance measurements from an independently calibrated spectroradiometer (Bentham DTM 300) were compared with the corresponding CCD measurements. Their agreement in the wavelength range of 310-500nm is within 0.5% +/- 1.1% (for SZA between 20 degrees and 70 degrees ). Aerosol optical depth (AOD) derived by the two instruments using direct Sun spectra and by a collocated Cimel sunphotometer [Aerosol Robotic network (AERONET)] agree to within 0.02 +/- 0.02 in the range of 315-870 nm. Significant correlation coefficients with a maximum of 0.99 in the range of 340-360 nm and a minimum of 0.90 at 870 nm were found between synchronous AOD measurements with the Bentham and the Cimel instruments.

With the mutual consent to use WSDL (Web Service Description Language) to describe web service interfaces and SOAP as the basic communication protocol, the cornerstone for web service-oriented architecture (WSOA) has been established. Considering the momentum observable by the growing number of specifications in the web service domain for the indispensable cross-cutting concern of identity management (IdM) it is still an open issue how a WSOA-aware IdM architecture is built and how it is linked with WSOA's main elements, the web services providing functional core concerns. In this paper we present an access control model for WSOA and a blueprint of a WSOA- aware authorization verification service which is part of the IdM architecture. We show the integration of this service with WSOA consisting of both basic and composite web services. Our solution has been tested and evaluated in an implementation case study.

Abstract A new spectroradiometer for spectral measurements of ultraviolet (UV) atmospheric radiation (290–400 nm) using a charge coupled device (CCD) as a detector is introduced. The instrument development is motivated by the need for measurements with (a) high accuracy in the UV-B spectral range (290–315 nm) for photochemistry applications and (b) high temporal resolution in quickly changing atmospheric conditions such as partial cloud cover. The new CCD instrument is mainly intended for airborne use. It allows fast data collection (&amp;lt;300 ms time resolution for each spectrum) with improved sensitivity in the UV spectral range. The instrumental setup and its characterization in terms of stray light, dark current, noise, and detection limits are described and compared to a spectroradiometer with a photodiode array (PDA) detector. The new CCD spectroradiometer has a one order of magnitude greater sensitivity than the PDA-based spectroradiometer. However, the stray light of the CCD instrument is wavelength dependent, which requires a more complicated data evaluation procedure than the PDA instrument. Comparison with other UV spectroradiometers (a PDA spectroradiometer and two ground-based double monochromators) shows the advantages of the CCD system for UV-B measurements of actinic flux densities and photolysis frequencies of ozone and nitrogen dioxide, and the improved performance compared to PDA spectroradiometers.

Abstract. In September 2002, the first INSPECTRO campaign to study the influence of clouds on the spectral actinic flux in the lower troposphere was carried out in East Anglia, England. Measurements of the actinic flux, the irradiance and aerosol and cloud properties were made from four ground stations and by aircraft. The radiation measurements were modelled using the uvspec model and ancillary data. For cloudless conditions, the measurements of the actinic flux were reproduced by 1-D radiative transfer modelling within the measurement and model uncertainties of about ±10%. For overcast days, the ground-based and aircraft radiation measurements and the cloud microphysical property measurements are consistent within the framework of 1-D radiative transfer and within experimental uncertainties. Furthermore, the actinic flux is increased by between 60-100% above the cloud when compared to a cloudless sky, with the largest increase for the optically thickest cloud. Correspondingly, the below cloud actinic flux is decreased by about 55-65%. Just below the cloud top, the downwelling actinic flux has a maximum that is seen in both the measurements and the model results. For broken clouds the traditional cloud fraction approximation is not able to simultaneously reproduce the measured above-cloud enhancement and below-cloud reduction in the actinic flux.

The vast majority of radiation measurements, including UV, refer to the radiation incident on a flat horizontal plate. However, this may not be the most appropriate way to specify radiation for bodies affected by UV, since they are rarely flat or horizontal. In particular the target molecules involved in atmospheric chemistry are approximately spherical and the actinic flux would be a better measure of the incident radiation. The ADMIRA project is addressing the issue of converting spectral UV irradiances to spectral actinic fluxes that can then be weighted with any required cross-section or action spectrum to give photolysis rates or biologically effective radiation incident on a sphere. The success with which this conversion can be made will depend on the prevailing atmospheric conditions and the knowledge of such at the time the irradiance measurements were made. Several different approaches to the conversion are being assessed, together with their associated uncertainties. These range from the simple empirical method to more complex radiative-transfer model based algorithms. Here we report on a coordinated campaign of simultaneous irradiance and actinic flux measurements supported by a wide range of ancillary measurements and their application to a simple empirical approach to converting irradiances to actinic fluxes.