| dc.date.accessioned |
2016-03-21T08:09:03Z |
und |
| dc.date.accessioned |
2017-10-24T12:04:03Z |
|
| dc.date.available |
2016-03-21T08:09:03Z |
und |
| dc.date.available |
2017-10-24T12:04:03Z |
|
| dc.date.issued |
2016-03-21T08:09:03Z |
|
| dc.identifier.uri |
http://radr.hulib.helsinki.fi/handle/10138.1/5377 |
und |
| dc.identifier.uri |
http://hdl.handle.net/10138.1/5377 |
|
| dc.title |
Precipitation estimation in urban areas by employing a dense-network of weather radars |
en |
| ethesis.department.URI |
http://data.hulib.helsinki.fi/id/3acb09b1-e6a2-4faa-b677-1a1b03285b66 |
|
| ethesis.department |
Institutionen för fysik |
sv |
| ethesis.department |
Department of Physics |
en |
| ethesis.department |
Fysiikan laitos |
fi |
| ethesis.faculty |
Matematisk-naturvetenskapliga fakulteten |
sv |
| ethesis.faculty |
Matemaattis-luonnontieteellinen tiedekunta |
fi |
| ethesis.faculty |
Faculty of Science |
en |
| ethesis.faculty.URI |
http://data.hulib.helsinki.fi/id/8d59209f-6614-4edd-9744-1ebdaf1d13ca |
|
| ethesis.university.URI |
http://data.hulib.helsinki.fi/id/50ae46d8-7ba9-4821-877c-c994c78b0d97 |
|
| ethesis.university |
Helsingfors universitet |
sv |
| ethesis.university |
University of Helsinki |
en |
| ethesis.university |
Helsingin yliopisto |
fi |
| dct.creator |
Hickman, Brandon |
|
| dct.issued |
2016 |
|
| dct.language.ISO639-2 |
eng |
|
| dct.abstract |
The aim of this thesis is the development of the highest quality quantitative precipitation estimate (QPE) for the Helsinki urban area through the creation of a quality controlled multi-radar composite. Weather radars suffer from a number of errors, and these are typically compounded when located near urban areas. Through the use of radar calibration, and several quality control methods, the three Helsinki area's radars (Kerava, Kumpula, Vantaa) were composited and a blended QPE was created.
The three C-band dual-polarimetric weather radars were calibrated through the self-consistency theory which relates Z, Zdr, to Kdp. The calibration was conducted over several summer days in 2014 for each radar, and all were found to be under-calibrated by about 2 dB. The influence of rain on top of the radome was also examined and found that wet radome attenuation can produce several dB offset in calibration.
Composites of Z and Kdp used weights were created to correct for non-hydrometeor class, beam blockage, attenuation of the beam, radome attenuation, range, and ground clutter. Noise in Kdp from light rain is reduced through utilizing the self-consistency theory. Composited reflectivity created significant improvements by filling data gaps, reducing errors, as well as providing additional observations for each echo. However minor errors, such as multi-trip echoes and speckle proceeded to the composite.
The blended QPE was created from the composite data to obtain the benefits of R(Kdp) in heavy rain and hail, while R(Z) was used in cases of light rain. Rain rate algorithms developed for the Helsinki climate were implemented to calculate the rain intensity for the selected precipitation type, which were determined through a series of threshold values obtained from literature. R(Kdp) allows better estimation in for heavy rain and hail because of being closer related to the hydrometers diameter as well as being immune to a number of errors present in Z.
The QPE created in this project provides improved precipitation intensity due to the use of multiple corrected radars. This data can be used for improved urban run-off modeling, emergency warnings and weather forecasting. However the method presented here is only applicable for liquid/mixed liquid and hail precipitation because of the impact of frozen hydrometeor on the dual-polarimetric parameters. Additional quality control methods and different precipitation estimates would be required for winter time precipitation. |
en |
| dct.language |
en |
|
| ethesis.language.URI |
http://data.hulib.helsinki.fi/id/languages/eng |
|
| ethesis.language |
English |
en |
| ethesis.language |
englanti |
fi |
| ethesis.language |
engelska |
sv |
| ethesis.thesistype |
pro gradu-avhandlingar |
sv |
| ethesis.thesistype |
pro gradu -tutkielmat |
fi |
| ethesis.thesistype |
master's thesis |
en |
| ethesis.thesistype.URI |
http://data.hulib.helsinki.fi/id/thesistypes/mastersthesis |
|
| ethesis.degreeprogram |
Atmosphere-Biosphere Studies |
en |
| dct.identifier.urn |
URN:NBN:fi-fe2017112251840 |
|
| dc.type.dcmitype |
Text |
|
