eprintid: 67024
rev_number: 36
eprint_status: archive
userid: 608
dir: disk0/00/06/70/24
datestamp: 2010-10-16 22:17:32
lastmod: 2021-10-16 22:50:37
status_changed: 2010-10-16 22:17:32
type: article
metadata_visibility: show
item_issues_count: 0
creators_name: Mackay, NG
creators_name: Chandler, RE
creators_name: Onof, C
creators_name: Wheater, HS
title: Disaggregation of spatial rainfall fields for hydrological modelling
ispublished: pub
divisions: UCL
divisions: B04
divisions: C06
divisions: F61
keywords: rainfall, disaggregation, General Circulation Model, Bayesian analysis, CLIMATE, COVERAGE, GCMS
note: © Author(s) 2001. This work is licensed under a Creative Commons License.
abstract: Meteorological models generate fields of precipitation and other climatological variables as spatial averages at the scale of the grid used for numerical solution. The grid-scale can be large, particularly for GCMs, and disaggregation is required, for example to generate appropriate spatial-temporal properties of rainfall for coupling with surface-boundary conditions or more general hydrological applications. A method is presented here which considers the generation of the wet areas and the simulation of rainfall intensities separately. For the first task, a nearest-neighbour Markov scheme, based upon a Bayesian technique used in image processing, is implemented so as to preserve the structural features of the observed rainfall. Essentially. the large-scale field and the previously disaggregated field are used as evidence in an iterative procedure which aims at selecting a realisation according to the joint posterior probability distribution. In the second task the morphological characteristics of the field of rainfall intensities are reproduced through a random sampling of intensities according to a beta distribution and their allocation to pixels chosen so that the higher intensities are more likely to be further from the dry areas. The components of the scheme are assessed for Arkansas-Red River basin radar rainfall (hourly averages) by disaggregating from 40 km x 40 km to 8 km x 8 km. The wet/dry scheme provides a good reproduction both of the number of correctly classified pixels and the coverage, while the intensity scheme generates fields with an adequate variance within the grid-squares. so that this scheme provides the hydrologist with a useful tool for the downscaling of meteorological model outputs.
date: 2001-06
publisher: EUROPEAN GEOPHYSICAL SOCIETY
official_url: http://www.hydrol-earth-syst-sci.net/5/165/2001/hess-5-165-2001.html
vfaculties: VMPS
oa_status: green
language: eng
primo: open
primo_central: open_green
article_type_text: Proceedings Paper
verified: verified_batch
elements_source: Web of Science
elements_id: 19272
doi: 10.5194/hess-5-165-2001
language_elements: EN
lyricists_name: Chandler, Richard
lyricists_id: RCHAN25
full_text_status: public
publication: HYDROLOGY AND EARTH SYSTEM SCIENCES
volume: 5
number: 2
pagerange: 165 - 173
event_location: THE HAGUE, NETHERLANDS
issn: 1027-5606
citation:        Mackay, NG;    Chandler, RE;    Onof, C;    Wheater, HS;      (2001)    Disaggregation of spatial rainfall fields for hydrological modelling.                   HYDROLOGY AND EARTH SYSTEM SCIENCES , 5  (2)   165 - 173.    10.5194/hess-5-165-2001 <https://doi.org/10.5194/hess-5-165-2001>.       Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/67024/1/hess-5-165-2001.pdf