The convective‐to‐total precipitation ratio and the “drizzling” bias in climate models

2021 ◽  
Author(s):  
Di Chen ◽  
Aiguo Dai ◽  
Alex Hall
Keyword(s):  
Climate Models ◽  
Total Precipitation ◽  
Precipitation Ratio

scholarly journals Precipitation Characteristics in Eighteen Coupled Climate Models

2006 ◽  
Vol 19 (18) ◽  
pp. 4605-4630 ◽  
Author(s):  
Aiguo Dai
Keyword(s):  
Climate Models ◽  
Global Climate Model ◽  
Precipitation Amount ◽  
Total Precipitation ◽  
Coupled Models ◽  
Central Pacific ◽  
Coupled Climate Models ◽  
Low Latitudes ◽  
Stratiform Precipitation ◽  
Precipitation Ratio

Abstract Monthly and 3-hourly precipitation data from twentieth-century climate simulations by the newest generation of 18 coupled climate system models are analyzed and compared with available observations. The characteristics examined include the mean spatial patterns, intraseasonal-to-interannual and ENSO-related variability, convective versus stratiform precipitation ratio, precipitation frequency and intensity for different precipitation categories, and diurnal cycle. Although most models reproduce the observed broad patterns of precipitation amount and year-to-year variability, models without flux corrections still show an unrealistic double-ITCZ pattern over the tropical Pacific, whereas the flux-corrected models, especially the Meteorological Research Institute (MRI) Coupled Global Climate Model (CGCM; version 2.3.2a), produce realistic rainfall patterns at low latitudes. As in previous generations of coupled models, the rainfall double ITCZs are related to westward expansion of the cold tongue of sea surface temperature (SST) that is observed only over the equatorial eastern Pacific but extends to the central Pacific in the models. The partitioning of the total variance of precipitation among intraseasonal, seasonal, and longer time scales is generally reproduced by the models, except over the western Pacific where the models fail to capture the large intraseasonal variations. Most models produce too much convective (over 95% of total precipitation) and too little stratiform precipitation over most of the low latitudes, in contrast to 45%–65% in convective form in the Tropical Rainfall Measuring Mission (TRMM) satellite observations. The biases in the convective versus stratiform precipitation ratio are linked to the unrealistically strong coupling of tropical convection to local SST, which results in a positive correlation between the standard deviation of Niño-3.4 SST and the local convective-to-total precipitation ratio among the models. The models reproduce the percentage of the contribution (to total precipitation) and frequency for moderate precipitation (10–20 mm day−1), but underestimate the contribution and frequency for heavy (>20 mm day−1) and overestimate them for light (<10 mm day−1) precipitation. The newest generation of coupled models still rains too frequently, mostly within the 1–10 mm day−1 category. Precipitation intensity over the storm tracks around the eastern coasts of Asia and North America is comparable to that in the ITCZ (10–12 mm day−1) in the TRMM data, but it is much weaker in the models. The diurnal analysis suggests that warm-season convection still starts too early in these new models and occurs too frequently at reduced intensity in some of the models. The results show that considerable improvements in precipitation simulations are still desirable for the latest generation of the world’s coupled climate models.

scholarly journals Historical Spatial and Temporal Climate Trends in Southern Ontario, Canada

2017 ◽  
Vol 56 (10) ◽  
pp. 2767-2787 ◽  
Author(s):  
Hussein Wazneh ◽  
M. Altaf Arain ◽  
Paulin Coulibaly
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Climate Indices ◽  
Total Precipitation ◽  
Southern Ontario ◽  
Temperature And Precipitation ◽  
Annual Total ◽  
Precipitation Indices ◽  
Temperature Indices

AbstractSpatial and temporal trends in historical temperature and precipitation extreme events were evaluated for southern Ontario, Canada. A number of climate indices were computed using observed and regional and global climate datasets for the area of study over the 1951–2013 period. A decrease in the frequency of cold temperature extremes and an increase in the frequency of warm temperature extremes was observed in the region. Overall, the numbers of extremely cold days decreased and hot nights increased. Nighttime warming was greater than daytime warming. The annual total precipitation and the frequency of extreme precipitation also increased. Spatially, for the precipitation indices, no significant trends were observed for annual total precipitation and extremely wet days in the southwest and the central part of Ontario. For temperature indices, cool days and warm night have significant trends in more than 90% of the study area. In general, the spatial variability of precipitation indices is much higher than that of temperature indices. In terms of comparisons between observed and simulated data, results showed large differences for both temperature and precipitation indices. For this region, the regional climate model was able to reproduce historical observed trends in climate indices very well as compared with global climate models. The statistical bias-correction method generally improved the ability of the global climate models to accurately simulate observed trends in climate indices.

scholarly journals Effect of Model Resolution on Intense and Extreme Precipitationinthe Mediterranean Region

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 699
Author(s):  
Dario Conte ◽  
Silvio Gualdi ◽  
Piero Lionello
Keyword(s):  
Climate Change ◽  
Mediterranean Region ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Model ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Global Climate Models ◽  
Total Precipitation ◽  
Model Resolution

This study explores the role of model resolution on the simulation of precipitation and on the estimate of its future change in the Mediterranean region. It compares the results of two regional climate models (RCMs, with two different horizontal grid resolutions, 0.44 and 0.11 degs, covering the whole Mediterranean region) and of the global climate model (GCM, 0.75 degs) that has provided the boundary conditions for them. The regional climate models include an interactive oceanic component with a resolution of 1/16 degs. The period 1960–2100 and the representative concentration pathways RCP4.5 and RCP8.5 are considered. The results show that, in the present climate, increasing resolution increases total precipitation and its extremes over steep orography, while it has the opposite effect over flat areas and the sea. Considering climate change, in all simulations, total precipitation will decrease over most of the considered domain except at the northern boundary, where it will increase. Extreme precipitation will increase over most of the northern Mediterranean region and decrease over the sea and some southern areas. Further, the overall probability of precipitation (frequency of wet days) significantly decreases over most of the region, but wet days will be characterized with precipitation intensity higher than the present. Our analysis shows that: (1) these projected changes are robust with respect to the considered range of model resolution; (2) increasing the resolution (within the considered resolution range) decreases the magnitude of these climate change effects. However, it is likely that resolution plays a less important role than other factors, such as the different physics of regional and global climate models. It remains to be investigated whether further increasing the resolution (and reaching the scale explicitly permitting convection) would change this conclusion.

scholarly journals Climate at the Equilibrium Line of Glaciers

1992 ◽  
Vol 38 (130) ◽  
pp. 397-411 ◽  
Author(s):  
Atsumu Ohmura ◽  
Peter Kasser ◽  
Martin Funk
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Equilibrium Line ◽  
Total Precipitation ◽  
Net Radiation ◽  
Specific Mass ◽  
Free Atmosphere ◽  
Long Wave ◽  
Annual Total ◽  
Meteorological Observations

AbstractThe relationships between temperature, precipitation and radiation on glacier equilibrium lines are investigated, using 70 glaciers for which the mass balance and meteorological observations have been carried out for sufficiently long periods. It is found that the characteristic climate at glacier equilibrium lines can be described using the summer 3 months’ temperature in a free atmosphere, annual total precipitation, and the sum of global and long-wave net radiation. All of these are measured at or very near the equilibrium-line altitudes. Then, it is shown how the shift of the equilibriumline will occur as a result of a climatic change. Finally, the effect of the shift of the equilibrium line on the annualmean specific mass balance is analytically derived and compared with observations. The present results make it possible to identify the altitudes in climate models where glacierization should begin, and to evaluate the mass-balance changes as a result of possible future changes in the climate.

scholarly journals Snow conditions in northern Europe: the dynamics of interannual variability versus projected long-term change

2021 ◽  
Vol 15 (4) ◽  
pp. 1677-1696
Author(s):  
Jouni Räisänen
Keyword(s):  
Interannual Variability ◽  
Climate Models ◽  
Snow Water Equivalent ◽  
Regional Climate ◽  
Northern Europe ◽  
Total Precipitation ◽  
Winter Climate ◽  
Mild Winter ◽  
Term Change

Abstract. Simulations by the EURO-CORDEX (European branch of the Coordinated Regional Climate Downscaling Experiment) regional climate models indicate a widespread future decrease in snow water equivalent (SWE) in northern Europe. This concurs with the negative interannual correlation between SWE and winter temperature in the southern parts of the domain but not with the positive correlation observed further north and over the Scandinavian mountains. To better understand these similarities and differences, interannual variations and projected future changes in SWE are attributed to anomalies or changes in three factors: total precipitation, the snowfall fraction of precipitation and the fraction of accumulated snowfall that remains on the ground (the snow-on-ground fraction). In areas with relatively mild winter climate, the latter two terms govern both the long-term change and interannual variability, resulting in less snow with higher temperatures. In colder areas, however, interannual SWE variability is dominated by variations in total precipitation. Since total precipitation is positively correlated with temperature, more snow tends to accumulate in milder winters. Still, even in these areas, SWE is projected to decrease in the future due to the reduced snowfall and snow-on-ground fractions in response to higher temperatures. Although winter total precipitation is projected to increase, its increase is smaller than would be expected from the interannual covariation of temperature and precipitation and is therefore insufficient to compensate the lower snowfall and snow-on-ground fractions. Furthermore, interannual SWE variability in northern Europe in the simulated warmer future climate is increasingly governed by variations in the snowfall and snow-on-ground fractions and less by variations in total precipitation.

scholarly journals Frequency of extreme precipitation increases extensively with event rareness under global warming

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
G. Myhre ◽  
K. Alterskjær ◽  
C. W. Stjern ◽  
Ø. Hodnebrog ◽  
L. Marelle ◽  
...  
Keyword(s):  
Global Warming ◽  
Extreme Precipitation ◽  
Climate Models ◽  
Climate Model ◽  
Total Precipitation ◽  
Extreme Precipitation Events ◽  
Intensity Changes ◽  
Climate Model Simulations ◽  
Event Based ◽  
Precipitation Events

Abstract The intensity of the heaviest extreme precipitation events is known to increase with global warming. How often such events occur in a warmer world is however less well established, and the combined effect of changes in frequency and intensity on the total amount of rain falling as extreme precipitation is much less explored, in spite of potentially large societal impacts. Here, we employ observations and climate model simulations to document strong increases in the frequencies of extreme precipitation events occurring on decadal timescales. Based on observations we find that the total precipitation from these intense events almost doubles per degree of warming, mainly due to changes in frequency, while the intensity changes are relatively weak, in accordance to previous studies. This shift towards stronger total precipitation from extreme events is seen in observations and climate models, and increases with the strength – and hence the rareness – of the event. Based on these results, we project that if historical trends continue, the most intense precipitation events observed today are likely to almost double in occurrence for each degree of further global warming. Changes to extreme precipitation of this magnitude are dramatically stronger than the more widely communicated changes to global mean precipitation.

scholarly journals Changes in extreme Integrated water Vapor Transport on the U.S. west coast in NA-CORDEX, and relationship to mountain and inland precipitation

2021 ◽  
Author(s):  
Mimi Hughes ◽  
Dustin Swales ◽  
James D. Scott ◽  
Michael Alexander ◽  
Kelly Mahoney ◽  
...  
Keyword(s):  
Water Vapor ◽  
Sierra Nevada ◽  
Great Basin ◽  
Climate Models ◽  
High Elevation ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Total Precipitation ◽  
Cool Season ◽  
The U.S

Abstract Western U.S. (WUS) rainfall and snowpack vary greatly on interannual and decadal timescales. This combined with their importance to water resources makes future projections of these variables highly societally relevant. Previous studies have shown that precipitation events in the WUS are influenced by the timing, positioning, and duration of extreme integrated water vapor transport (IVT) events (e.g., atmospheric rivers) along the coast. We investigate end-of-21st-century projections of WUS precipitation and IVT in a collection of regional climate models (RCMs) from the North American Coordinated Regional Downscaling Experiment (NA-CORDEX). Several of the NA-CORDEX RCMs project a decrease in cool season precipitation at high elevation (e.g., across the Sierra Nevada) with a corresponding increase in the Great Basin of the U.S. We explore the causes of this terrain-related precipitation change in a subset of the NA-CORDEX RCMs through an examination of IVT-events. Projected changes in frequency and duration of IVT-events depend on the event's extremity: By the end of the century extreme IVT-events increase in frequency whereas moderate IVT-events decrease in frequency. Furthermore, in the future, total precipitation across the WUS generally increases during extreme IVT-events, whereas total precipitation from moderate IVT-events decreases across higher elevations. Thus, we argue that the mean cool season precipitation decreases at high elevations and increases in the Great Basin are largely determined by changes in moderate IVT-events which are projected to be less frequent and bring less high-elevation precipitation.

scholarly journals Future precipitation changes over the eastern Adriatic and Dinaric Alps areas in the latest EURO-CORDEX ensemble

2021 ◽  
Author(s):  
Sarah Ivušić ◽  
Ivan Güttler ◽  
Kristian Horvath
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Extreme Precipitation ◽  
Climate Models ◽  
Future Climate Change ◽  
Climate Change Signal ◽  
Historical Period ◽  
Climate Projections ◽  
Intensity Increase ◽  
Total Precipitation

<p>The topographically complex coastal-mountainous region of the eastern Adriatic and Dinaric Alps is one of the rainiest areas in the Mediterranean and particularly vulnerable to climate change. The aim is to estimate the future climate change of precipitation over this region over which research on this subject is still limited. We use the climate projections from the latest EURO-CORDEX ensemble at 0.11° resolution. The ensemble is comprised of 14 regional climate models (RCMs) driven by eight CMIP5 global climate models (GCMs), a total of 68 members. The climate change signal is examined for the far future period (2071-2100) with respect to the historical period (1971-2000) for one greenhouse gases concentration scenario, particularly for RCP8.5. Total precipitation shows a considerable reduction in summer months, while in winter it is projected to increase in the northern part of the region and to decrease in southern parts, displaying the known south-north gradients. Accordingly, the number of rainy days is projected to decrease by the end of the century, especially during summer over the entire region and in winter over the southern parts. However, the precipitation intensity increase can be expected by the end of the century, especially during the winter months, while in the summer there is no clear consensus between different models. Also, an increase in extreme precipitation is projected during the winter months, while during summer months a similar south-north gradient is shown as for total precipitation. A more detailed analysis for multiple future periods and greenhouse gases concentration scenarios, with an emphasis on extreme precipitation, is planned.</p>

scholarly journals Climate at the Equilibrium Line of Glaciers

1992 ◽  
Vol 38 (130) ◽  
pp. 397-411 ◽  
Author(s):  
Atsumu Ohmura ◽  
Peter Kasser ◽  
Martin Funk
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Equilibrium Line ◽  
Total Precipitation ◽  
Net Radiation ◽  
Specific Mass ◽  
Free Atmosphere ◽  
Long Wave ◽  
Annual Total ◽  
Meteorological Observations

AbstractThe relationships between temperature, precipitation and radiation on glacier equilibrium lines are investigated, using 70 glaciers for which the mass balance and meteorological observations have been carried out for sufficiently long periods. It is found that the characteristic climate at glacier equilibrium lines can be described using the summer 3 months’ temperature in a free atmosphere, annual total precipitation, and the sum of global and long-wave net radiation. All of these are measured at or very near the equilibrium-line altitudes. Then, it is shown how the shift of the equilibriumline will occur as a result of a climatic change. Finally, the effect of the shift of the equilibrium line on the annualmean specific mass balance is analytically derived and compared with observations. The present results make it possible to identify the altitudes in climate models where glacierization should begin, and to evaluate the mass-balance changes as a result of possible future changes in the climate.

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