Browsing by Subject "Temperature"

Now showing 1 - 5 of 5

A scanning eye-safe rotational Raman lidar in the ultraviolet for measurements of tropospheric temperature fields
(2009) Radlach, Marcus; Wulfmeyer, Volker
Within the frame of the virtual Institute COSI-TRACKS the first scanning rotational Raman lidar has been developed and deployed successfully in two large field campaigns. This has allowed new investigations of the convective boundary layer and contributed to studies on the initiation of convection during the PRINCE campaign (PRediction, Identification and trackiNg of Convective cElls) in July 2006 and the COPS experiment (Convective and Orographically-induced Precipitation Study) from June to August 2007. The University of Hohenheim rotational Raman lidar was deployed in both these campaigns on Hornisgrinde (48.61 °N, 8.20 °E, 1161 m above sea level), the highest peak in the Northern Black Forest in southwest Germany. The lidar provides measurements of atmospheric temperature fields in the troposphere with high spatial and temporal resolution at day and night. Daytime scanning temperature measurements within a range of 3 km using a temporal resolution of 169 s and a moving average of 300 m in range show statistical temperature uncertainties of less than 1 K while pointing at 21 directions. Temperature uncertainties of less than 1 K are achieved during nighttime up to a range of 8 km using a temporal resolution of 3 minutes and a range resolution of 300 m. The lidar resolves also turbulence in the convective boundary layer, e.g., at 470 m height with a temporal resolution of 10 s and statistical uncertainties of only 0.41 K. In addition to temperature, also the particle backscatter coefficient and the particle extinction coefficient are measured independently. The instrument operates with a primary wavelength of 355 nm. This has instrumental advantages compared to 532 nm but also yields eye-safety beyond a range of 500 m which facilitates the deployment. Highly efficient spectral separation of the atmospheric backscatter signals is performed by a polychromator with narrow-band interference filters in a sequential setup. The spectral characteristics of these filters were optimized with respect to high measurement performance in the daytime planetary boundary layer and the lower free troposphere. Pioneering measurements of the 2-dimensional temperature distribution in the lower troposphere in the vicinity of a mountain ridge are presented.
Convective-scale data assimilation of thermodynamic lidar data into the weather research and forecasting model
(2022) Thundathil, Rohith Muraleedharan; Wulfmeyer, Volker
This thesis studies the impact of assimilating temperature and humidity profiles from ground-based lidar systems and demonstrates its value for future short-range forecast. Thermodynamic profile obtained from the temperature Raman lidar and the water-vapour differential absorption lidar of the University of Hohenheim during the High Definition of Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) project Observation Prototype Experiment (HOPE) are assimilated into the Weather Research and Forecasting model Data Assimilation (WRFDA) system by means of a new forward operator. The impact study assimilating the high-resolution thermodynamic lidar data was conducted using variational and ensemble-based data assimilation methods. The first part of the thesis describes the development of the thermodynamic lidar operator and its implementation through a deterministic DA impact study. The operator facilitates the direct assimilation of water vapour mixing ratio (WVMR), a prognostic variable in the WRF model, without conversion to relative humidity. Undesirable cross sensitivities to temperature are avoided here so that the complete information content of the observation with respect to the water vapour is provided. The assimilation experiments were performed with the three-dimensional variational (3DVAR) DA system with a rapid update cycle (RUC) with hourly frequency over ten hours. The DA experiments with the new operator outperformed the previously used relative humidity operator, and the overall humidity and temperature analyses improved. The simultaneous assimilation of temperature and WVMR resulted in a degradation of the temperature analysis compared to the improvement observed in the sole temperature assimilation experiment. The static background error covariance matrix (B) in the 3DVAR was identified as the reason behind this behaviour. The correlation between the temperature and WVMR variables in the background error covariance matrix of the 3DVAR, which is static and not flow-dependent, limited the improvement in temperature. The second part of the thesis provides a solution for overcoming the static B matrix issue. A hybrid, ensemble-based approach was applied using the Ensemble Transform Kalman Filter (ETKF) and the 3DVAR to add flow dependency to the B matrix. The hybrid experiment resulted in a 50% lower temperature and water vapour root mean square error (RMSE) than the 3DVAR experiment. Comparisons against independent radiosonde observations showed a reduction of RMSE by 26% for water vapour and 38% for temperature. The planetary boundary layer (PBL) height of the analyses also showed an improvement compared to the available ceilometer. The impact of assimilating a single lidar vertical profile spreads over a 100 km radius, which is promising for future assimilation of water vapour and temperature data from operational lidar networks for short-range weather forecasting. A forecast improvement was observed for 7 hours lead time compared with the ceilometer derived planetary boundary layer height observations and 4 hours with Global Navigation Satellite System (GNSS) derived integrated water vapour observations. With the help of sophisticated DA systems and a robust network of lidar systems, the thesis throws light on the future of short-range operational forecasting.
Do biotic and abiotic factors influence the prevalence of a common parasite of the invasive alien ladybird Harmonia axyridis?
(2022) Haelewaters, Danny; Hiller, Thomas; Ceryngier, Piotr; Eschen, René; Gorczak, Michał; Houston, Makenna L.; Kisło, Kamil; Knapp, Michal; Landeka, Nediljko; Pfliegler, Walter P.; Zach, Peter; Aime, M. Catherine; Nedvěd, Oldřich
Hesperomyces virescens (Ascomycota, Laboulbeniales), a fungal ectoparasite, is thus far reported on Harmonia axyridis from five continents: North and South America, Europe, Africa, and Asia. While it is known that He. virescens can cause mortality of Ha. axyridis under laboratory conditions, the role of biotic and abiotic factors in influencing the distribution of He. virescens in the field is unknown. We collected and screened 3,568 adult Ha. axyridis from 23 locations in seven countries in Central Europe between October and November 2018 to test the effect of selected host characters and climate and landscape variables on the infection probability with He. virescens. Mean parasite prevalence of He. virescens on Ha. axyridis was 17.9%, ranging among samples from 0 to 46.4%. Host sex, climate, and landscape composition did not have any significant effect on the infection probability of He. virescens on Ha. axyridis. Two color forms, f. conspicua and f. spectabilis, had a significantly lower parasite prevalence compared to the common Ha. axyridis f. novemdecimsignata.
Effect of reactive and non-reactive additive treatment on the recovery of phosphorus from biogas digestate
(2023) Uppuluri, Naga Sai Tejaswi; Dinkler, Konstantin; Ran, Xueling; Guo, Jianbin; Müller, Joachim; Oechsner, Hans
The annual phosphate (PO43−) utilization has increased, leading to a depletion of existing sources of phosphorus (P). To overcome this, digestate as a source to recover P is being investigated. Due to the abundance of nutrients, the digestate from an agricultural biogas plant is used as fertilizer for crops. The separation of solids and liquids from the digestate by a screw press is the simplest form of concentrating, therefore, recovering PO43−. This is the most commonly employed method in existing biogas plants. However, the separation is not very efficient as only 20–30% of P is recovered in the solid phase. The goal of this study is to increase the separation efficiency and recover more P into the solid phase, in order to improve the transportability. For this, separation trials at a laboratory scale were performed for five experimental groups, with biochar and straw flour as non-reactive additives and kieserite as a reactive additive. In addition, untreated digestate was studied as a control. The control and the treatment with biochar and straw flour were carried out at 25 °C, while the treatment with kieserite was performed at 25 °C and 50 °C. The separation trails were performed at treatment times of 0 h, 1 h, 2 h, 8 h, and 20 h. The results showed that the treatment with additives had a beneficial effect on the recovery of P. It was noted that kieserite treatment at 25 °C and 50 °C bound about 61% of the total P present in the digestate to the solid phase. A sequential extraction was performed to study the effect of additives on the recovery of different P species. The results concluded that, compared to biochar and straw flour, kieserite was efficient in recovering the non-labile fractions (NaOH-P and HCl-P) of P, which act as slow-release fertilizers. This study shows that the use of additives, especially kieserite, has a positive influence on recovering P from digestate, and further research to optimize the recovery process would be beneficial.
Temperaturgesteuerte Zellzahlregelung für Bioreaktoren
(2021) Loges, Karin Martina; Hitzmann, Bernd
Biopharmaceutical cell culture processes are multi-stage processes. Starting with low cell numbers and small culture volumes, the upstream process takes place step by step in a reactor cascade with increasing volume. To achieve constant product quality and high reproducibility, each reactor must be seeded with a defined initial cell concentration and all cultures must show very similar growth rates. However, batch to batch variations of growth rates can occur in biological systems and disrupt the reproducibility of the inoculation with defined cell concentrations. In order to control the growth rate and thus increase the reproducibility from batch to batch, a self-adapting cell number controller was developed. This controller can be rapidly introduced in a typical industrial (biopharma) environment. At the beginning of the process, the user specifies the desired seed cell concentration and the point in time at which this cell concentration should be reached. In the following, the cell number controller automatically regulates the growth rate of the cells during the process and leads it to the specified process end parameters. The regulation of the cell growth rate is achieved with adjustment of the process temperature. In the development phase of the cell number controller, a converted reactor system was adjusted and qualified. The temperature dependency of the biomass probe was examined. After that, the dependence of the cell growth rate on the temperature was analysed, described in the form of a mathematical model and implemented in a control algorithm. The required temperature is calculated with the aid of a numerical optimization process, using the previously derived mathematical model of the temperature-dependent growth rate, the online measured values and the specifications of the user. In order to achieve greater flexibility within the upstream process and to be able to react to disruptions in the process flow, it is also possible to dynamically adjust the target parameter, set by the user at the beginning, during the running process. To optimize the controller, it was analysed how the mathematical algorithm can be adapted to different cell clones and which tests are absolutely necessary to determine the cell specific, temperature-dependent growth rate. In this context, a self-learning algorithm was implemented so that it is now possible to use the controller without preliminary tests and to ensure constant control quality in the event of possible changes in the cell growth of a cell clone. During this research project, the functionality of the cell number controller, such as the changes in the process end parameters during the ongoing process and the iterative-adaptive optimization of the mathematical algorithm on different cell clones, could be verified experimentally. The biological reactions of the cells to the temperature changes within the cell number-controlled precultures and within the subsequent production stage were also analysed. Furthermore, a possible influence on the quantity and quality of the products was examined. All examined biological reactions of the cells during the cell count regulation showed a reversible behaviour, which are normalized in the following process steps at 37 °C within two days. In addition, no negative influence of the cell-number-controlled preculture on product quality and quantity could be determined. In summary, a functionally adaptable cell number controller was developed and tested with two different CHO cell clones for a possible influence on cell metabolism, apoptosis, product quantity and Quality.