In contrast to in-situ temperature sensors, remote sensing technologies e. However, the temporal resolution of satellite data is limited comparing to in-situ measurements. Numerical models and all source of observations have large uncertainty coming from different sources such as errors of approximation and truncation, uncertain model inputs, error in measuring devices and etc. Data assimilation DA is able to sequentially update the model state variables by considering the uncertainty in model and observations and estimate the model states and outputs more accurately.
ITC MSc theses
Data Assimilation has been proposed for multiple water resources studies that require rapid employment of incoming observations to update and improve accuracy of operational prediction models. The usefulness of DA approaches in assimilating water temperature observations from different types of monitoring technologies e. Assimilating of water temperature measurements from satellites can introduce biases in the updated numerical model of water bodies because the physical region represented by these measurements do not directly correspond with the numerical model's representation of the water column.
The main research objective of this study is to efficiently assimilate multi-sensor water temperature data into the hydrodynamic model of water bodies in order to improve the model accuracy.
Results showed that the proposed adjustment approach used in this study for four-dimensional analysis of a reservoir provides reasonably accurate surface layer and water column temperature forecasts, in spite of the use of a fairly small ensemble. Assimilation of adjusted remote sensing data using ensemble Kalman Filter technique improved the overall root mean square difference between modeled surface layer temperatures and the adjusted remotely sensed skin temperature observations from 5. In addition, the overall error in the water column temperature predictions when compared with in-situ observations also decreased from 1.
The shape of segregation : the role of urban form in immigrant assimilation
In contrast, doing data assimilation without the proposed temperature adjustment would have increased this error to 1. The most effective parameters to calculate water temperature were investigated and perturbed among the acceptable range to create the ensembles. Results show that water temperature is more sensitive to inflow temperature, air temperature, solar radiation, wind speed, flow rate, and wet bulb temperature respectively.
Results also show in contrast to in-situ data assimilation, remote sensing data assimilation was able to effectively improve the spatial error of the model.
Assimilation of in-situ observation improved the model efficiency at observation site. However, the model error increased by time and after less than two days, the model predictions of updated model were the same as base model before data assimilation.
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Hence, a maximum acceptable error between model and measurements was defined based on the application of model. Remote sensing data were assimilated into the model as they become available to improve the model accuracy for the entire river. In-situ data were also assimilated into the model when the error between model and observations exceeds the maximum error.
In addition, the average spatial error reduced from 2. Istok, Jonathan D. Miller, Robert N.
Global climate reconstruction across time and space using data assimilation
Relationships Parents: This work has no parents. Although, the satellite instruments are delivering an unprecedented wealth of observations of a number of stratospheric trace gases with global coverage, they are scattered and have a limited resolution in space or time. Combining these measurements and applying advanced data assimilation techniques to compare benefits from satellite and air borne data, and to analyse the chemical composition of the tropopause and lower stratosphere, was the issue of this work.
For this purpose, a model grid refinement and full revision of the chemical mechanism were performed. The resolution of the horizontal grid points was increased from about km to km, resulting in 23 grid points per model level.
Spatial assimilation thesis
The vertical resolution was increased with twelve additional layers, especially in the UTLS region. Hence, the vertical separation between grid levels is now less than 1 km below 22 km altitude.
The chemistry module was extended and revised to better represent chemical processes in the UTLS region. In total, a number of photolysis, gas phase, and heterogeneous reactions of 51 stratospheric trace gases is considered by the chemistry module now.
A comprehensive set of case studies has been conducted in order to test and evaluate the extended system. Retrievals of various stratospheric trace gases derived from measurements of the Earth Observing System Microwave Limb Sounder, as well as retrievals of aircraft measurements have been assimilated.
The analyses show a perfect performance with respect to the assimilated ozone observations.