Spatial downscaling of radar-derived rainfall field by two-dimensional wavelet transform
Downscaling of rainfall fields, either as images or products of global circulation models, have been the motive of many hydrologists and hydro-meteorologists. The main concern in downscaling is to transform high-resolution properties of the rainfall field to lower resolution without introducing erro...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IWA Publishing
2020-06-01
|
| Series: | Hydrology Research |
| Subjects: | |
| Online Access: | http://hr.iwaponline.com/content/51/3/456 |
| _version_ | 1818270748103409664 |
|---|---|
| author | Vahid Nourani Armin Farshbaf S. Adarsh |
| author_facet | Vahid Nourani Armin Farshbaf S. Adarsh |
| author_sort | Vahid Nourani |
| collection | DOAJ |
| description | Downscaling of rainfall fields, either as images or products of global circulation models, have been the motive of many hydrologists and hydro-meteorologists. The main concern in downscaling is to transform high-resolution properties of the rainfall field to lower resolution without introducing erroneous information. In this paper, rainfall fields obtained from Next Generation Weather Surveillance Radar (NEXRAD) Level III were examined in the wavelet domain which revealed sparsity for wavelet coefficients. The proposed methodology in this work employs a concept named Standardized Rainfall Fluctuation (SRF) to overcome the sparsity of rainfall fields in wavelet domain which also exhibited scaling behaviors in a range of scales. SRFs utilizes such scaling behaviors where upscaled versions of the rainfall fields are downscaled to their actual size, using a two-dimensional discrete wavelet transform, to examine the reproduction of the rainfall fields. Furthermore, model modifications were employed to enhance the accuracy. These modifications include removing the negative values while conserving the mean and applying a non-overlapping kernel to restore high-gradient clusters of rainfall fields. The calculated correlation coefficient, statistical moments, determination coefficient and spatial pattern display a good agreement between the outputs of the downscaling method and the observed rainfall fields. |
| first_indexed | 2024-12-12T21:15:12Z |
| format | Article |
| id | doaj.art-cc1a8b7fc97e4443a751c06c49541d39 |
| institution | Directory Open Access Journal |
| issn | 1998-9563 2224-7955 |
| language | English |
| last_indexed | 2024-12-12T21:15:12Z |
| publishDate | 2020-06-01 |
| publisher | IWA Publishing |
| record_format | Article |
| series | Hydrology Research |
| spelling | doaj.art-cc1a8b7fc97e4443a751c06c49541d392022-12-22T00:11:47ZengIWA PublishingHydrology Research1998-95632224-79552020-06-0151345646910.2166/nh.2020.165165Spatial downscaling of radar-derived rainfall field by two-dimensional wavelet transformVahid Nourani0Armin Farshbaf1S. Adarsh2 Center of Excellence in Hydroinformatics, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran Center of Excellence in Hydroinformatics, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran Department of Civil Engineering, TKM College of Engineering, Kollam, India Downscaling of rainfall fields, either as images or products of global circulation models, have been the motive of many hydrologists and hydro-meteorologists. The main concern in downscaling is to transform high-resolution properties of the rainfall field to lower resolution without introducing erroneous information. In this paper, rainfall fields obtained from Next Generation Weather Surveillance Radar (NEXRAD) Level III were examined in the wavelet domain which revealed sparsity for wavelet coefficients. The proposed methodology in this work employs a concept named Standardized Rainfall Fluctuation (SRF) to overcome the sparsity of rainfall fields in wavelet domain which also exhibited scaling behaviors in a range of scales. SRFs utilizes such scaling behaviors where upscaled versions of the rainfall fields are downscaled to their actual size, using a two-dimensional discrete wavelet transform, to examine the reproduction of the rainfall fields. Furthermore, model modifications were employed to enhance the accuracy. These modifications include removing the negative values while conserving the mean and applying a non-overlapping kernel to restore high-gradient clusters of rainfall fields. The calculated correlation coefficient, statistical moments, determination coefficient and spatial pattern display a good agreement between the outputs of the downscaling method and the observed rainfall fields.http://hr.iwaponline.com/content/51/3/456scaling behaviorspatial downscalingwavelet transformweather surveillance radar |
| spellingShingle | Vahid Nourani Armin Farshbaf S. Adarsh Spatial downscaling of radar-derived rainfall field by two-dimensional wavelet transform Hydrology Research scaling behavior spatial downscaling wavelet transform weather surveillance radar |
| title | Spatial downscaling of radar-derived rainfall field by two-dimensional wavelet transform |
| title_full | Spatial downscaling of radar-derived rainfall field by two-dimensional wavelet transform |
| title_fullStr | Spatial downscaling of radar-derived rainfall field by two-dimensional wavelet transform |
| title_full_unstemmed | Spatial downscaling of radar-derived rainfall field by two-dimensional wavelet transform |
| title_short | Spatial downscaling of radar-derived rainfall field by two-dimensional wavelet transform |
| title_sort | spatial downscaling of radar derived rainfall field by two dimensional wavelet transform |
| topic | scaling behavior spatial downscaling wavelet transform weather surveillance radar |
| url | http://hr.iwaponline.com/content/51/3/456 |
| work_keys_str_mv | AT vahidnourani spatialdownscalingofradarderivedrainfallfieldbytwodimensionalwavelettransform AT arminfarshbaf spatialdownscalingofradarderivedrainfallfieldbytwodimensionalwavelettransform AT sadarsh spatialdownscalingofradarderivedrainfallfieldbytwodimensionalwavelettransform |