scholarly journals Modeling the Hydroclimatology of Kuwait: The Role of Subcloud Evaporation in Semiarid Climates

2008 ◽  
Vol 21 (12) ◽  
pp. 2976-2989 ◽  
Author(s):  
Marc P. Marcella ◽  
Elfatih A. B. Eltahir
Keyword(s):  
Boundary Conditions ◽  
Interannual Variability ◽  
Large Scale ◽  
Climate Model ◽  
Regional Climate ◽  
Critical Role ◽  
Rain Gauge ◽  
Annual Rainfall ◽  
Semiarid Region

Abstract A new subcloud layer evaporation scheme is incorporated into Regional Climate Model, version 3 (RegCM3), to better simulate the rainfall distribution over a semiarid region around Kuwait. The new scheme represents subcloud layer evaporation of convective as well as large-scale rainfall. Model results are compared to observations from rain gauge data networks and satellites. The simulations show significant response to the incorporation of subcloud layer evaporation as a reduction by as much as 20% in annual rainfall occurs over the region. As a result, the new model simulations of annual rainfall are within 15% of observations. In addition, results indicate that the interannual variability of rainfall simulated by RegCM3 is sensitive to the specification of boundary conditions. For example, forcing RegCM3’s lateral boundary conditions with the 40-yr ECMWF Re-Analysis (ERA-40) data, instead of NCEP–NCAR’s Reanalysis Project 2 (NNRP2), reduces interannual variability by over 25%. Moreover, with subcloud layer evaporation incorporated and ERA-40 boundary conditions implemented, the model’s bias and root-mean-square error are significantly reduced. Therefore, the model’s ability to reproduce observed annual rainfall and the year-to-year variation of rainfall is greatly improved. Thus, these results elucidate the critical role of this natural process in simulating the hydroclimatology of semiarid climates. Last, a large discrepancy between observation datasets over the region is observed. It is believed that the inherent characteristics that are used to construct these datasets explain the differences observed in the annual and interannual variability of Kuwait’s rainfall.

scholarly journals Observations and  Modelling of Precipitation  in the Southern Alps of  New Zealand

2021 ◽  
Author(s):  
◽  
Stephen John Stuart
Keyword(s):  
New Zealand ◽  
Climate Model ◽  
Regional Climate ◽  
Rain Gauge ◽  
Southern Alps ◽  
Annual Rainfall ◽  
Mean Annual Precipitation ◽  
Mountain Range ◽  
Mountainous Regions ◽  
Orographic Rainfall

<p>Precipitation in the central Southern Alps affects glaciation, river flows and key economic activities, yet there is still uncertainty about its spatial distribution and primary influences. Long-term and future patterns of New Zealand precipitation can be estimated by the HadRM3P regional climate model (RCM) - developed by the United Kingdom Met Office - but orographic rainfall in the steep and rugged topography of the Southern Alps is difficult to simulate accurately at the 30-km resolution of the RCM. To quantify empirical relationships, observations of surface rainfall were gathered from rain gauges covering a broad region of the South Island. In four transects of the Hokitika, Franz Josef and Haast regions, the mean annual precipitation maxima of objectively interpolated profiles are consistently located 7-11 km southeast of the New Zealand Alpine Fault. The magnitude and shape of the rainfall profile across the Southern Alps are strongly influenced by the 850-hPa wind direction to the north of the mountain range, as determined by comparing rain-gauge observations to wind vectors from NCEP/NCAR Reanalysis 1. The observed profile of orographically enhanced rainfall was incorporated into a trivariate spline in order to interpolate precipitation simulated by the RCM. This downscaling method significantly improved the RCM's estimates of mean annual rainfall at stations in the Southern Alps region from 1971 to 2000, and RCM projections of future rainfall in mountainous regions may be similarly refined via this technique. The improved understanding of the observed rainfall distribution in the Southern Alps, as gained from this analysis, has a range of other hydrological applications and is already being used in 'downstream' modelling of glaciers.</p>

scholarly journals Observations and  Modelling of Precipitation  in the Southern Alps of  New Zealand

2021 ◽  
Author(s):  
◽  
Stephen John Stuart
Keyword(s):  
New Zealand ◽  
Climate Model ◽  
Regional Climate ◽  
Rain Gauge ◽  
Southern Alps ◽  
Annual Rainfall ◽  
Mean Annual Precipitation ◽  
Mountain Range ◽  
Mountainous Regions ◽  
Orographic Rainfall

<p>Precipitation in the central Southern Alps affects glaciation, river flows and key economic activities, yet there is still uncertainty about its spatial distribution and primary influences. Long-term and future patterns of New Zealand precipitation can be estimated by the HadRM3P regional climate model (RCM) - developed by the United Kingdom Met Office - but orographic rainfall in the steep and rugged topography of the Southern Alps is difficult to simulate accurately at the 30-km resolution of the RCM. To quantify empirical relationships, observations of surface rainfall were gathered from rain gauges covering a broad region of the South Island. In four transects of the Hokitika, Franz Josef and Haast regions, the mean annual precipitation maxima of objectively interpolated profiles are consistently located 7-11 km southeast of the New Zealand Alpine Fault. The magnitude and shape of the rainfall profile across the Southern Alps are strongly influenced by the 850-hPa wind direction to the north of the mountain range, as determined by comparing rain-gauge observations to wind vectors from NCEP/NCAR Reanalysis 1. The observed profile of orographically enhanced rainfall was incorporated into a trivariate spline in order to interpolate precipitation simulated by the RCM. This downscaling method significantly improved the RCM's estimates of mean annual rainfall at stations in the Southern Alps region from 1971 to 2000, and RCM projections of future rainfall in mountainous regions may be similarly refined via this technique. The improved understanding of the observed rainfall distribution in the Southern Alps, as gained from this analysis, has a range of other hydrological applications and is already being used in 'downstream' modelling of glaciers.</p>

scholarly journals On understanding the role of South Asian High on the Onset and Withdrawal of the Indian Monsoon

2021 ◽  
Author(s):  
Nishtha Agrawal ◽  
Vivek Pandey
Keyword(s):  
South Asian ◽  
Large Scale ◽  
Climate Model ◽  
Indian Monsoon ◽  
Regional Climate ◽  
Reanalysis Data ◽  
Hadley Cell ◽  
South Asian High ◽  
Annual Variability

Abstract The Indian monsoon is always considered to be a large-scale process that has a profound impact on the agriculture and economic conditions of India. The present study addresses the role of South Asian High (SAH) and subtropical westerly jet (STJ) on the onset and withdrawal of Indian monsoon. For this purpose, we have utilized the output of the Regional Climate Model (RegCM v4.6) and reanalysis ERA5 pressure level data for 24 years (1982–2005) of study. We begin our analysis with the evaluation of Tibetan Plateau (TP) heating and its connection with different atmospheric factors during the seasonal transition of monsoon is perused. We have further tried to decipher the link between SAH and inter-annual variability of monsoon. Our analysis shows the efficiency of the model in simulating inter-annual variability of monsoon onset and withdrawal features. The days of onset and withdrawal simulated by the model have a similar mid-latitude connection as that obtained from the reanalysis data. The vertical structure of the Hadley cell and the horizontal position of SAH have been produced realistically during the transition of the monsoon. We found that the change in meridional position of STJ has a significant impact on phase-shifting of arrival and departure of monsoon. This repositioning of STJ in a meridional direction is strongly correlated to the upper-level high developed over the eastern periphery of the western pacific which is an important component of monsoon flow over the Bay of Bengal. Thus the zonal position of SAH is observed to have direct implications on the onset and withdrawal dates of India.

scholarly journals A Dynamical Downscaling Case Study for Typhoons in Southeast Asia Using a Regional Climate Model

2008 ◽  
Vol 136 (5) ◽  
pp. 1806-1815 ◽  
Author(s):  
Frauke Feser ◽  
Hans von Storch
Keyword(s):  
Boundary Conditions ◽  
Southeast Asia ◽  
Regional Climate Model ◽  
Large Scale ◽  
Climate Model ◽  
Regional Climate ◽  
Lateral Boundary ◽  
Spectral Nudging ◽  
Lateral Boundary Conditions ◽  
Initial Starting

Abstract This study explores the possibility of reconstructing the weather of Southeast Asia for the last decades using an atmospheric regional climate model, the Climate version of the Lokal-Modell (CLM). For this purpose global National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalyses data were dynamically downscaled to 50 km and in a double-nesting approach to 18-km grid distance. To prevent the regional model from deviating significantly from the reanalyses with respect to large-scale circulation and large-scale weather phenomena, a spectral nudging technique was used. The performance of this technique in dealing with Southeast Asian typhoons is now examined by considering an ensemble of one simulated typhoon case. This analysis is new insofar as it deals with simulations done in the climate mode (so that any skill of reproducing the typhoon is not related to details of initial conditions), is done in ensemble mode (the same development is described by several simulations), and is done with a spectral nudging constraint (so that the observed large-scale state is enforced in the model domain). This case indicates that tropical storms that are coarsely described by the reanalyses are correctly identified and tracked; considerably deeper core pressure and higher wind speeds are simulated compared to the driving reanalyses. When the regional atmospheric model is run without spectral nudging, significant intraensemble variability occurs; also additional, nonobserved typhoons form. Thus, the insufficiency of lateral boundary conditions alone for determining the details of the dynamic developments in the interior becomes very clear. The same lateral boundary conditions are consistent with different developments in the interior. Several sensitivity experiments were performed concerning varied grid distances, different initial starting dates of the simulations, and changed spectral nudging parameters.

The effect of climate change on urban drainage: an evaluation based on regional climate model simulations

2006 ◽  
Vol 54 (6-7) ◽  
pp. 9-15 ◽  
Author(s):  
M. Grum ◽  
A.T. Jørgensen ◽  
R.M. Johansen ◽  
J.J. Linde
Keyword(s):  
Climate Change ◽  
Extreme Precipitation ◽  
Climate Model ◽  
Regional Climate ◽  
Rain Gauge ◽  
Urban Drainage ◽  
Extreme Precipitation Events ◽  
Rainfall Extremes ◽  
The Future ◽  
Precipitation Events

That we are in a period of extraordinary rates of climate change is today evident. These climate changes are likely to impact local weather conditions with direct impacts on precipitation patterns and urban drainage. In recent years several studies have focused on revealing the nature, extent and consequences of climate change on urban drainage and urban runoff pollution issues. This study uses predictions from a regional climate model to look at the effects of climate change on extreme precipitation events. Results are presented in terms of point rainfall extremes. The analysis involves three steps: Firstly, hourly rainfall intensities from 16 point rain gauges are averaged to create a rain gauge equivalent intensity for a 25 × 25 km square corresponding to one grid cell in the climate model. Secondly, the differences between present and future in the climate model is used to project the hourly extreme statistics of the rain gauge surface into the future. Thirdly, the future extremes of the square surface area are downscaled to give point rainfall extremes of the future. The results and conclusions rely heavily on the regional model's suitability in describing extremes at time-scales relevant to urban drainage. However, in spite of these uncertainties, and others raised in the discussion, the tendency is clear: extreme precipitation events effecting urban drainage and causing flooding will become more frequent as a result of climate change.

Hydrological evaluation of high-resolution precipitation estimates from the WRF model in the Third Pole river basins

2021 ◽  
Author(s):  
He Sun ◽  
Fengge Su ◽  
Zhihua He ◽  
Tinghai Ou ◽  
Deliang Chen ◽  
...  
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Hydrological Modeling ◽  
Climate Model ◽  
Regional Climate ◽  
Wrf Model ◽  
Infiltration Capacity ◽  
Flood Prediction ◽  
Daily Streamflow ◽  
Precipitation Estimates

AbstractIn this study, two sets of precipitation estimates based on the regional Weather Research and Forecasting model (WRF) –the high Asia refined analysis (HAR) and outputs with a 9 km resolution from WRF (WRF-9km) are evaluated at both basin and point scales, and their potential hydrological utilities are investigated by driving the Variable Infiltration Capacity (VIC) large-scale land surface hydrological model in seven Third Pole (TP) basins. The regional climate model (RCM) tends to overestimate the gauge-based estimates by 20–95% in annual means among the selected basins. Relative to the gauge observations, the RCM precipitation estimates can accurately detect daily precipitation events of varying intensities (with absolute bias < 3 mm). The WRF-9km exhibits a high potential for hydrological application in the monsoon-dominated basins in the southeastern TP (with NSE of 0.7–0.9 and bias of -11% to 3%), while the HAR performs well in the upper Indus (UI) and upper Brahmaputra (UB) basins (with NSE of 0.6 and bias of -15% to -9%). Both the RCM precipitation estimates can accurately capture the magnitudes of low and moderate daily streamflow, but show limited capabilities in flood prediction in most of the TP basins. This study provides a comprehensive evaluation of the strength and limitation of RCMs precipitation in hydrological modeling in the TP with complex terrains and sparse gauge observations.

Sign in / Sign up

Export Citation Format

Share Document