The Effect of Grid Spacing and Domain Size on the Quality of Ensemble Regional Climate Downscaling over South Asia during the Northeasterly Monsoon

Jian-Hua Qian; Zubair, Lareef
July 2010
Monthly Weather Review;Jul2010, Vol. 138 Issue 7, p2780
Academic Journal
The performance of an ensemble-based dynamical regional climate downscaling system is evaluated over southern Asia in a northeasterly monsoon season for different choices in grid spacing and domain size. A seven-member ensemble of the ECHAM4.5 global climate model at a resolution of about 300-km grid size was used to drive the RegCM3 regional climate model with grid sizes of 100, 50, 25, and 20 km, respectively. The performance is reported in detail over Sri Lanka. Two sets of regional model runs were undertaken to assess the effect of grid spacing and model domain size on the downscaling performance. The RegCM3 simulation with 100-km grid size significantly underestimates the height of the central mountain range in Sri Lanka, in a manner that is too coarse to capture orographic influences on the rainfall. However, the RegCM3 simulations with grid sizes from 20 to 50 km capture mesoscale features that arise from uplift condensation on the windward side of the monsoon winds due to the topography. These simulations also capture the orographic influences on the month-to-month rainfall over Sri Lanka that were absent in the ECHAM4.5. While the “small domain” runs [where only the forcings for the region immediately around Sri Lanka (4°–11°N, 76°–85°E) are used] are computationally more efficient, the results are overly controlled by the lateral boundary driving of the ECHAM4.5 so they inherit large uncertainty from the seven ECHAM4.5 realizations used for the RegCM3 ensemble runs. The “large domain” simulation used a domain comprising both land and ocean (approximately 4°S–22°N, 65°–96°E). The large-domain group of simulations produced reasonable spatial distribution of precipitation over the region. Moreover, the ensemble spread was considerably reduced in the large-domain high-resolution runs. Therefore, fine enough grid resolution (25 km or less) and sufficiently large domain size are both needed to simulate the essential features of precipitation in this tropical and monsoonal region.


Related Articles

  • Century-scale events in monsoonal climate over the past 24,000 years. Sirocko, F.; Sarnthein, M. // Nature;7/22/1993, Vol. 364 Issue 6435, p322 

    Presents evidence from a high-resolution record of oxygen isotopes and carbonate spanning the past 24,000 calendar years that the response of the southwest monsoon over the Arabian Sea to long-term, gradual insolation changes occurred in several distinct events of less than 300 years duration. ...

  • Climatic change at high elevation sites: An overview. Beniston, M.; Diaz, H.F. // Climatic Change;Jul/Aug97, Vol. 36 Issue 3/4, p233 

    Provides an overview of climatic changes that have been observed from 1896 to 1996 at certain high-elevation sites. Documentation of climate-sensitive environmental indicators; Measurement of natural variability of climate in mountains; Characterization of present and past climatological...

  • MARIA NEDEALCOV: "AGROCLIMATIC RESOURCES IN THE CONTEXT OF CLIMATE CHANGE" - Institute of Ecology and Geography, Academy of Sciences of Moldova, Chisinau, 2012, 306p. Donisă, Ioan // Present Environment & Sustainable Development;2013, Vol. 7 Issue 1, p317 

    The article presents an overview of the content of the study "Agroclimatic Resources in the Context of Climate Change," by Maria Nedealcov of the Institute of Ecology and Geography, Academy of Sciences of Modova in Chisinau.

  • Difficulties in Correctly Modelling the East Asian Winter Monsoon.  // CO2 Science;5/7/2014, Vol. 17 Issue 19, p5 

    The article presents a study led by researcher Hainan Gong and others on the weather condition of the East Asian Winter Monsoon using coordinated climate change experiments. The authors report in "The climatology and inter-annual variability of the East Asian Winter Monsoon in CMIP5 models"...

  • THE CONTRIBUTION OF HUMAN-INDUCED CLIMATE CHANGE TO THE DROUGHT OF 2014 IN THE SOUTHERN LEVANT REGION. BERGAOUI, K.; MITCHELL, D.; ZAABOUL, R.; MCDONNELL, R.; OTTO, F.; ALLEN, M. // Bulletin of the American Meteorological Society;Dec2015 Supplement Explaining Extreme Events, pS66 

    The article examines the role of anthropogenic climate change on the 2014 drought in the southern Levant region. Topics covered include extremes in long dry periods and low rainfall, intrusion of low-level continental polar air, expansion of the subtropical high over the Mediterranean Basin and...

  • Characterization of risk/exposure to climate extremes for the Brazilian Northeast-case study: Rio Grande do Norte. Silva, Bruce; Lucio, Paulo // Theoretical & Applied Climatology;Oct2015, Vol. 122 Issue 1/2, p59 

    Climate change would increase the risk of floods or droughts. So far, only a few studies have projected changes in extremes on a regional or local scale. None of these studies relied on multiple climate proxies. Only some studies have started to estimate the exposure to flooding or drought as a...

  • Pakistan monsoon floods: climate change or geological rundown? Riaz, Mohammad // Journal of Himalayan Earth Science;2010, Vol. 43, p72 

    This article describes a study which examined whether the July-August 2010 floods in Pakistan were caused by regular geological processes or by climate change. Researchers analyzed some of the flood-laden sand beds near Sukkur and Bahawalpur which would help develop a time-series of flooding...

  • Millennial-Scale Climate Variability During the Holocene.  // CO2 Science;7/30/2014, Vol. 17 Issue 31, p1 

    The article discusses a study on millennial-scale climate variability during the Holocene. It references several studies including "Holocene Periodicity in North Atlantic Climate and Deep-Ocean Flow South of Iceland," published in an issue of "Nature," "Coherent High- and Low-Latitude Climate...

  • A social and ecological imperative for ecosystem-based adaptation to climate change in the Pacific Islands. Hills, T.; Carruthers, T.; Chape, S.; Donohoe, P. // Sustainability Science;Jul2013, Vol. 8 Issue 3, p455 

    Climate change is predicted to have a range of impacts on Pacific Island ecosystems and the services they provide for current and future development. There are a number of characteristics that can make adaptation approaches that utilise the benefits of ecosystems a compelling and viable...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics