Evaluation of Modeled Precipitation in Oceanic Extratropical Cyclones Using IMERG

ABSTRACT Using a high-spatial- and high-temporal-resolution precipitation dataset, Integrated Multi-satellite Retrievals for GPM (IMERG), extratropical cyclone precipitation is evaluated in two reanalyses and two climate models. Based on cyclone-centered composites, all four models overestimate precipitation in the western subsiding and dry side of the cyclones, and underestimate the precipitation in the eastern ascending and moist side. By decomposing the composites into frequency of occurrence and intensity (mean precipitation rate when precipitating), the analysis reveals a tendency for all four models to overestimate frequency and underestimate intensity, with the former issue dominating in the western half and the latter in the eastern half of the cyclones. Differences in frequency are strongly dependent on cyclone environmental moisture, while the differences in intensity are strongly impacted by the strength of ascent within the cyclone. There are some uncertainties associated with the observations: IMERG might underreport frozen precipitation and possibly exaggerate rates in vigorously ascending regions. Nevertheless, the analysis suggests that all models produce extratropical cyclone precipitation too often and too lightly. These biases have consequences when evaluating the changes in precipitation characteristics with changes in cyclone properties: the models disagree on the magnitude of the change in precipitation intensity with a change in environmental moisture and in precipitation frequency with a change in cyclone strength. This complicates accurate predictions of precipitation changes in a changing climate.

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Projected future daily characteristics of African precipitation based on global (CMIP5, CMIP6) and regional (CORDEX, CORDEX-CORE) climate models

Climate Dynamics ◽

10.1007/s00382-021-05859-w ◽

2021 ◽

Author(s):

Alessandro Dosio ◽

Martin W. Jury ◽

Mansour Almazroui ◽

Moetasim Ashfaq ◽

Ismaila Diallo ◽

...

Keyword(s):

East Africa ◽

Southern Africa ◽

Climate Models ◽

Precipitation Intensity ◽

Regional Models ◽

The West ◽

Precipitation Frequency ◽

Global Models ◽

Dry Spells ◽

Precipitation Characteristics

AbstractWe provide an assessment of future daily characteristics of African precipitation by explicitly comparing the results of large ensembles of global (CMIP5, CMIP6) and regional (CORDEX, CORE) climate models, specifically highlighting the similarities and inconsistencies between them. Results for seasonal mean precipitation are not always consistent amongst ensembles: in particular, global models tend to project a wetter future compared to regional models, especially over the Eastern Sahel, Central and East Africa. However, results for other precipitation characteristics are more consistent. In general, all ensembles project an increase in maximum precipitation intensity during the wet season over all regions and emission scenarios (except the West Sahel for CORE) and a decrease in precipitation frequency (under the Representative Concentration Pathways RCP8.5) especially over the West Sahel, the Atlas region, southern central Africa, East Africa and southern Africa. Depending on the season, the length of dry spells is projected to increase consistently by all ensembles and for most (if not all) models over southern Africa, the Ethiopian highlands and the Atlas region. Discrepancies exist between global and regional models on the projected change in precipitation characteristics over specific regions and seasons. For instance, over the Eastern Sahel in July–August most global models show an increase in precipitation frequency but regional models project a robust decrease. Global and regional models also project an opposite sign in the change of the length of dry spells. CORE results show a marked drying over the regions affected by the West Africa monsoon throughout the year, accompanied by a decrease in mean precipitation intensity between May and July that is not present in the other ensembles. This enhanced drying may be related to specific physical mechanisms that are better resolved by the higher resolution models and highlights the importance of a process-based evaluation of the mechanisms controlling precipitation over the region.

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Changes in the Risk of Extratropical Cyclones in Eastern Australia

Journal of Climate ◽

10.1175/jcli-d-12-00192.1 ◽

2013 ◽

Vol 26 (4) ◽

pp. 1403-1417 ◽

Cited By ~ 22

Author(s):

Andrew J. Dowdy ◽

Graham A. Mills ◽

Bertrand Timbal ◽

Yang Wang

Keyword(s):

Large Scale ◽

Climate Models ◽

East Coast ◽

Global Climate ◽

Absolute Risk ◽

Extreme Rainfall ◽

Global Climate Models ◽

Extratropical Cyclone ◽

Extratropical Cyclones ◽

Eastern Australia

Abstract The east coast of Australia is a region of the world where a particular type of extratropical cyclone, known locally as an east coast low, frequently occurs with severe consequences such as extreme rainfall, winds, and waves. The likelihood of formation of these storms is examined using an upper-tropospheric diagnostic applied to three reanalyses and three global climate models (GCMs). Strong similarities exist among the results derived from the individual reanalyses in terms of their seasonal variability (e.g., winter maxima and summer minima) and interannual variability. Results from reanalyses indicate that the threshold value used in the diagnostic method is dependent on the spatial resolution. Results obtained when applying the diagnostic to two of the three GCMs are similar to expectations given their spatial resolutions, and produce seasonal cycles similar to those from the reanalyses. Applying the methodology to simulations from these two GCMs for both current and future climate in response to increases in greenhouse gases indicates a reduction in extratropical cyclone occurrence of about 30% from the late twentieth century to the late twenty-first century for eastern Australia. In addition to the absolute risk of formation of these extratropical cyclones, spatial climatologies of occurrence are examined for the broader region surrounding eastern Australia. The influence of large-scale modes of atmospheric and oceanic variability on the occurrence of these storms in this region is also discussed.

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Daily precipitation characteristics of RegCM4 and WRF in China and their interannual variations

Climate Research ◽

10.3354/cr01621 ◽

2020 ◽

Vol 82 ◽

pp. 97-115

Author(s):

X Kong ◽

A Wang ◽

X Bi ◽

J Wei

Keyword(s):

Extreme Precipitation ◽

Climate Models ◽

Daily Precipitation ◽

Regional Climate ◽

Precipitation Amount ◽

Extreme Rainfall ◽

Horizontal Resolution ◽

Interannual Variations ◽

Precipitation Frequency ◽

Precipitation Characteristics

To evaluate and clarify the daily precipitation characteristics (i.e. amount, frequency and intensity) of the regional climate models (RCMs) in China, long-term simulations were carried out using RegCM4.5 and Weather Research and Forecasting model (WRF), which were nested within the European Centre for Medium-Range Weather Forecasts (ECMWF)’s 20th century reanalysis (ERA-20C) between 1901 and 2010. The 2 RCMs were initially run at a resolution of 50 km. Analyses mainly compared the model-simulated climatic means and interannual variations of precipitation characteristics with those of dense and high-quality station observations (STN) from 1961-2010. Both models satisfactorily reproduced the seasonal mean precipitation amount, but they overestimated its frequency and underestimated its intensity. Extreme rainfall frequency was also underestimated by both RCMs. In winter (DJF), the interannual variabilities in dry days, light precipitation and moderate precipitation were well represented by both models. However, they poorly reproduced the counterparts of extreme precipitation in winter. In summer (JJA), the 2 RCMs performed well in simulating the interannual variability of extreme precipitation. Comparably, RegCM outperformed WRF in reproducing the spatial patterns of precipitation amount, interannual variations in extreme precipitation and rain events. By contrast, WRF better represented precipitation frequency in different sub-regions overall. Moreover, when the horizontal resolution of RegCM was increased from 50 to 25 km, there was a slight improvement in the representation of precipitation amount and intensity. Our results show that RCMs perform well in reproducing actual climatic means and interannual variations of daily precipitation characteristics in China, and that high-resolution RCM simulations can produce improved results for precipitation amount and intensity.

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The Role of Plant CO2 Physiological Forcing in Shaping Future Daily-Scale Precipitation

Journal of Climate ◽

10.1175/jcli-d-16-0603.1 ◽

2017 ◽

Vol 30 (7) ◽

pp. 2319-2340 ◽

Cited By ~ 29

Author(s):

Christopher B. Skinner ◽

Christopher J. Poulsen ◽

Robin Chadwick ◽

Noah S. Diffenbaugh ◽

Richard P. Fiorella

Keyword(s):

Boundary Layer ◽

Radiative Forcing ◽

Climate Models ◽

Regional Scale ◽

Heat Fluxes ◽

Annual Number ◽

Climate System Model ◽

Precipitation Characteristics ◽

Daily Scale ◽

Precipitation Changes

Continued anthropogenic CO2 emissions are expected to drive widespread changes in precipitation characteristics. Nonetheless, projections of precipitation change vary considerably at the regional scale between climate models. Here, it is shown that the response of plant physiology to elevated CO2, or CO2 physiological forcing drives widespread hydrologic changes distinct from those associated with CO2 radiative forcing and has a role in shaping regional-scale differences in projected daily-scale precipitation changes. In a suite of simulations with the Community Climate System Model, version 4 (CCSM4), reduced stomatal conductance from projected physiological forcing drives large decreases in transpiration and changes the distribution of daily-scale precipitation within and adjacent to regions of dense vegetation and climatologically high transpiration. When atmospheric conditions are marginally favorable for precipitation, reduced transpiration dries the boundary layer and increases the likelihood of dry day occurrence. In CCSM4, the annual number of dry days increases by upward of 15 days yr−1 over tropical land and the continental midlatitudes. Decreases in transpiration from physiological forcing also increase the number of heavy precipitation events by up to 8 days yr−1 in many tropical forest regions. Despite reductions in the land surface contribution to atmospheric moisture, diminished surface latent heat fluxes warm the forest boundary layer and increase moisture convergence from nearby oceans, enhancing instability. The results suggest that consideration of the radiative impacts of CO2 alone cannot account for projected regional-scale differences in daily precipitation changes, and that CO2 physiological forcing may contribute to differences in projected precipitation characteristics among climate models.

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Variations of future precipitations in Poyang Lake Watershed under the global warming using a spatiotemporally distributed downscaling model

10.5194/hess-2018-286 ◽

2018 ◽

Author(s):

Ling Zhang ◽

Xiaoling Chen ◽

Jianzhong Lu ◽

Dong Liang

Keyword(s):

General Circulation ◽

Climate Models ◽

Poyang Lake ◽

Dry Season ◽

Global Climate Models ◽

Wet Season ◽

Temporal And Spatial Distribution ◽

Precipitation Frequency ◽

Change Rate ◽

Precipitation Changes

Abstract. Traditional statistic downscaling methods are processed on independent stations, which ignores spatial correlations and spatiotemporal heterogeneity. In this study, a spatiotemporally distributed downscaling model (STDDM) was developed. The method interpolated observations and GCMs (Global Climate Models) simulations to continual finer grids; then created relationship, respectively for each grid at each time. We applied the STDDM in precipitation downscaling of Poyang Lake Watershed using MRI-CGCM3 (Meteorological Research Institute Coupled Ocean-Atmosphere General Circulation Model3), with an acceptant uncertainty of ≤ 4.9 %, and created future precipitation changes from 1998 to 2100 (1998–2012 in the historical and 2013–2100 in RCP8.5 scenario). The precipitation changes showed increasing heterogeneities in temporal and spatial distribution under the future climate warming. In the temporal pattern, the wet season precipitation increased with change rate (CR) = 7.33 mm/10a (11.66 mm/K) while the dry season precipitations decreased with CR = −0.92 mm/10a (−4.31 mm/K). The extreme precipitation frequency and intensity were enhanced with CR = 0.49 days/10a and 7.2 mm•day-1/10a respectively. In the spatial pattern, precipitations in wet or dry season showed an uneven change rate over the watershed, and the wet or dry area exhibited a wetter or drier condition in the wet or dry season. Analysis with temperature increases showed precipitation changes appeared significantly (p

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Productivity of Ospreys, Pandion haliaetus, Affected by Water Levels Near Loon Lake, Saskatchewan, 1975-2002

The Canadian Field-Naturalist ◽

10.22621/cfn.v124i3.1077 ◽

2010 ◽

Vol 124 (3) ◽

pp. 219

Author(s):

C. Stuart Houston ◽

Frank Scott ◽

Rob B. Tether

Keyword(s):

Breeding Success ◽

Water Levels ◽

Lake Levels ◽

The West ◽

Canadian Data ◽

Human Use ◽

The Town ◽

Western Half ◽

Eastern Half

Between 1975 and 2002, diminished breeding success of Ospreys was associated with drought and falling lake levels in the western half of our study area near the town of Loon Lake, west-central Saskatchewan. Only 46% of nest attempts were successful in the west compared to 72% in the east, producing 0.88 young per accessible nest in the west and 1.42 in the east. Breeding success was greater in the eastern half, where water levels were stable, in spite of increased human use of the resort lakes there. Our unique long-term Canadian data base results support Ogden's 1977 prediction that Osprey productivity may decrease when water levels drop and fish populations are reduced.

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VARDA (VArved sediments DAtabase) – providing and connecting proxy data from annually laminated lake sediments

10.5194/essd-2020-55 ◽

2020 ◽

Author(s):

Arne Ramisch ◽

Alexander Brauser ◽

Mario Dorn ◽

Cecile Blanchet ◽

Brian Brademann ◽

...

Keyword(s):

High Resolution ◽

Lake Sediments ◽

Climate Models ◽

Detailed Comparison ◽

High Temporal Resolution ◽

Proxy Data ◽

Varved Sediments ◽

Proxy Records ◽

Data Compilation ◽

Varved Lake Sediments

Abstract. Varved lake sediments provide long climatic records with high temporal resolution and low associated age uncertainty. Robust and detailed comparison of well-dated and annually laminated sediment records is crucial for reconstructing abrupt and regionally time-transgressive changes as well as validation of spatial and temporal trajectories of past climatic changes. The VARved sediments DAtabase (VARDA) presented here is the first data compilation for varve chronologies and associated palaeoclimatic proxy records. The current version 1.0 allows detailed comparison of published varve records from 95 lakes. VARDA is freely accessible and was created to assess outputs from climate models with high-resolution terrestrial palaeoclimatic proxies. VARDA additionally provides a technical environment that enables to explore the database of varved lake sediments using a connected data-model and can generate a state-of-the-art graphic representation of multi-site comparison. This allows to reassess existing chronologies and tephra events to synchronize and compare even distant varved lake records. Furthermore, the present version of VARDA permits to explore varve thickness data. In this paper, we report in detail on the data mining and compilation strategies for the identification of varved lakes and assimilation of high-resolution chronologies as well as the technical infrastructure of the database. Additional paleoclimate proxy data will be provided in forthcoming updates. The VARDA graph-database and user interface can be accessed online at https://varve.gfz-potsdam.de, all datasets of version 1.0 are available at http://doi.org/10.5880/GFZ.4.3.2019.003 (Ramisch et al., 2019).

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Effects of soil rewetting and thawing on soil gas fluxes: a review of current literature and suggestions for future research

Biogeosciences Discussions ◽

10.5194/bgd-8-9847-2011 ◽

2011 ◽

Vol 8 (5) ◽

pp. 9847-9899 ◽

Cited By ~ 9

Author(s):

D.-G. Kim ◽

R. Vargas ◽

B. Bond-Lamberty ◽

M. R. Turetsky

Keyword(s):

Climate Models ◽

Gas Production ◽

Global Climate Models ◽

Soil Gas ◽

Future Research ◽

High Temporal Resolution ◽

Short Term ◽

Frozen Soils ◽

Gas Fluxes ◽

The Impact

Abstract. The rewetting of dry soils and the thawing of frozen soils are short-term, transitional phenomena in terms of hydrology and the thermodynamics of soil systems. The impact of these short-term phenomena on larger scale ecosystem fluxes has only recently been fully appreciated, and a growing number of studies show that these events affect various biogeochemical processes including fluxes of soil gases such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ammonia (NH3) and nitric oxide (NO). Global climate models predict that future climatic change is likely to alter the frequency and intensity of drying-rewetting events and thawing of frozen soils, highlighting the importance of understanding how rewetting and thawing will influence soil gas fluxes. Here we summarize findings in a new database based on 338 studies conducted from 1956 to 2010, and highlight open research questions. The database revealed conflicting results following rewetting and thawing in various terrestrial ecosystems, ranging from large increases in gas fluxes to non-significant changes. An analysis of published field studies (n = 142) showed that after rewetting or thawing, CO2, CH4, N2O, NO and NH3 fluxes increase from pre-event fluxes following a power function, with no significant differenced among gases. We discuss possible mechanisms and controls that regulate flux responses, and note that a high temporal resolution of flux measurements is critical to capture rapid changes in gas fluxes after these soil perturbations. Finally, we propose that future studies should investigate the interactions between biological (i.e. microbial community and gas production) and physical (i.e. flux, diffusion, dissolution) changes in soil gas fluxes, and explore synergistic experimental and modelling approaches.

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Divergent responses of biomass accumulation and its allocation to the altered precipitation regimes among different degraded grasslands in China

10.21203/rs.3.rs-243440/v1 ◽

2021 ◽

Author(s):

Tianxue Yang ◽

Junda Chen ◽

Xiaoyue Zhong ◽

Xuechen Yang ◽

Gui Wang ◽

...

Keyword(s):

Climate Models ◽

Plant Biomass ◽

Inorganic Nitrogen ◽

Precipitation Amount ◽

Soil Layer ◽

Ecosystem Functions ◽

Precipitation Frequency ◽

Positive Effects ◽

Altered Precipitation ◽

Precipitation Regimes

Abstract Purpose Climate models predict shifts in precipitation patterns characterized by increased precipitation amount and decreased frequency for semi-arid grasslands in northeast China. However, under these novel climatic conditions, potential differences in plant biomass and its allocation among different degraded grasslands remain unclear.Methods We conducted a mesocosm experiment to test the effects of higher precipitation amount (increased by 50% from the long-term mean) and lower frequency (decreased by 50%) on plant biomass and allocation in the lightly degraded (LDG), moderately degraded (MDG), and severely degraded grasslands (SDG).Results Lower precipitation frequency promoted belowground biomass (BGB), while reducing aboveground biomass (AGB) allocation through enhancing soil water variability. Higher precipitation amount enhanced AGB in LDG and MDG, but not in SDG due to less soil inorganic nitrogen. Lower precipitation frequency weakened the positive effects of higher precipitation amount on biomass. Under altered precipitation, adjustment of AGB vs. BGB allocation was the primary biomass allocation strategy in LDG and SDG. However, to maintain water acquirement, plants in MDG preferred to adjust root vertical distribution, and allocated more roots to the deep soil layer where had a relatively stable water source. This strategy was driven by the changes in plant community composition of the dominant species in MDG.Conclusions The findings of this research emphasized the importance of considering the degradation level of grasslands when predicting the responses of the ecosystem functions to the projected changes in precipitation regime. These findings are critical for making feasible decisions for the sustainable management of degraded grasslands.

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Farmers and the Market in Antebellum America: A View from the Georgia Upcountry

The Journal of Economic History ◽

10.1017/s0022050700049032 ◽

1987 ◽

Vol 47 (3) ◽

pp. 627-647 ◽

Cited By ~ 7

Author(s):

David F. Weiman

Keyword(s):

Local Development ◽

Household Wealth ◽

Capital Gains ◽

Farm Households ◽

Market Development ◽

Antebellum America ◽

Market Production ◽

Lower South ◽

Western Half ◽

Eastern Half

The Upcountry of the Lower South was located on the periphery of the antebellum cotton economy, but some of its subregions were integrated into the market system in the 1850s. An analysis of sample counties in the Georgia Upcountry demonstrates that the spread of market production into the western half of the region depended on local development which created opportunities for diversified market production and increased household wealth through capital gains on improvements. The absence of market development in the eastern half of the region, in contrast, limited the wealth of farm households, reinforcing their economic isolation.

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