Influence of Open Water Bodies on the Modeling of Summertime Convection over the Canadian Prairies

2017 ◽  
Vol 18 (6) ◽  
pp. 1583-1594
Author(s):  
Deepti Joshi ◽  
Marco Carrera ◽  
Stephane Bélair ◽  
Sylvie Leroyer
Keyword(s):  
Convective Available Potential Energy ◽  
Open Water ◽  
Water Bodies ◽  
Convective Precipitation ◽  
Precipitation Event ◽  
Canadian Prairies ◽  
Water Fraction ◽  
Weather Patterns ◽  
Global Environmental ◽  
Land Water

Abstract There are numerous water features on the Canadian landscapes that are not monitored. Specifically, there are water bodies over the prairies and Canadian shield regions of North America that are ephemeral in nature and could have a significant influence on convective storm generation and local weather patterns through turbulent exchanges of sensible and latent heat between the land and the atmosphere. In this study a series of numerical experiments is performed with Environment and Climate Change Canada’s Global Environmental Multiscale (GEM) model at 2.5-km grid spacing to examine the sensitivity of the atmospheric boundary layer and the resulting precipitation to the presence of open water bodies. Operationally, the land–water fraction in GEM is specified by means of static geophysical databases that do not change with time. Uncertainty is introduced in this study into this land–water fraction and the sensitivity of the resulting precipitation is quantified for a convective precipitation event occurring over the Canadian Prairies in the summer of 2014. The results indicate that with an increase in open water bodies, accumulated precipitation, peak precipitation amounts, and intensities decrease. Moreover, shifts are seen in times of peak for both precipitation amounts and intensities, in the order of increasing wetness. Additionally, with an increase in open water bodies, convective available potential energy decreases and convective inhibition increases, indicating suppression of forcing for convective precipitation.

Constructing Mediterranean wetland open water dynamics using a new 18-year MODIS-derived surface water fraction dataset

2020 ◽  
Author(s):  
Linlin Li ◽  
Anton Vrieling ◽  
Andrew Skidmore ◽  
Tiejun Wang
Keyword(s):  
Time Series ◽  
Surface Water ◽  
Temporal Dynamics ◽  
Open Water ◽  
Water Area ◽  
Water Bodies ◽  
Water Dynamics ◽  
Water Fraction ◽  
Wide Range

<p>Wetlands are among the most biodiverse ecosystems in the world, due largely to their dynamic hydrology. Frequent observations by satellite sensors such as the Moderate Resolution Imaging Spectrometer (MODIS) allow for monitoring the seasonal, inter-annual and long-term dynamics of surface water extent. However, existing MODIS-based studies have only demonstrated this for large water bodies despite the ecological importance of smaller-sized wetland systems. In this paper, we constructed the temporal dynamics of surface water extent for 340 individual water bodies in the Mediterranean region between 2000 and 2017, using a previously developed 8-day 500 m MODIS surface water fraction (SWF) dataset. These water bodies has a wide range of size, specifically 0.01 km<sup>2</sup> and larger. We then compared the water extent time series derived from MODIS SWF with those derived from a Landsat-based dataset. Results showed that MODIS- and Landsat-derived water extent time series showed a high correlation (r = 0.81) for more dynamic water bodies. Our MODIS SWF dataset can also effectively monitor the variability of very small water bodies (<1 km<sup>2</sup>) when comparing with Landsat data as long as the temporal variability in their surface water area was high. We conclude that MODIS SWF is a useful product to help understand hydrological dynamics for both small and larger-sized water bodies, and to monitor their seasonal, intermittent, inter-annual and long-term changes.</p>

scholarly journals Assimilation of space-based passive microwave soil moisture retrievals and the correction for a dynamic open water fraction

2012 ◽  
Vol 9 (1) ◽  
pp. 1013-1039 ◽  
Author(s):  
B. T. Gouweleeuw ◽  
A. I. J. M. van Dijk ◽  
J. P. Guerschman ◽  
P. Dyce ◽  
R. A. M. de Jeu ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Surface Soil ◽  
Low Frequency ◽  
Open Water ◽  
Water Bodies ◽  
Surface Soil Moisture ◽  
Near Surface ◽  
Small Areas ◽  
Water Fraction ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. The large observation footprint of low-frequency satellite microwave emissions complicates the interpretation of near-surface soil moisture retrievals. While the effect of sub-footprint lateral heterogeneity is relatively limited under unsaturated conditions, open water bodies, if not accounted for, cause a strong positive bias in the satellite-derived soil moisture retrieval. This bias is generally assumed static and associated with large, continental lakes and coastal areas. Temporal changes in the extent of smaller water bodies as small as a few percent of the sensor footprint size, however, can cause significant and dynamic biases. We analysed the influence of such small open water bodies near-surface soil moisture retrieval data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) for three areas in Oklahoma, USA. Differences between on-ground observations, model estimates and AMSR-E retrievals were compared to dynamic estimates of open water fraction, one retrieved from a global daily record based on higher frequency AMSR-E data and another derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). The comparisons demonstrates that seasonally varying biases of up to 30 vol.% soil water content can be attributed to the presence of relatively small areas (<5%) of open water in or near the sensor footprint. These errors need to be addressed, either through elimination or accurate characterization, if the soil moisture retrievals are to be used effectively in a data assimilation scheme.

scholarly journals Space-based passive microwave soil moisture retrievals and the correction for a dynamic open water fraction

2012 ◽  
Vol 16 (6) ◽  
pp. 1635-1645 ◽  
Author(s):  
B. T. Gouweleeuw ◽  
A. I. J. M. van Dijk ◽  
J. P. Guerschman ◽  
P. Dyce ◽  
M. Owe
Keyword(s):  
Soil Moisture ◽  
Surface Soil ◽  
Open Water ◽  
Water Bodies ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Vegetation Density ◽  
Surface Soil Moisture ◽  
Near Surface ◽  
Water Fraction

Abstract. The large observation footprint of low-frequency satellite microwave emissions complicates the interpretation of near-surface soil moisture retrievals. While the effect of sub-footprint lateral heterogeneity is relatively limited under unsaturated conditions, open water bodies (if not accounted for) cause a strong positive bias in the satellite-derived soil moisture retrieval. This bias is generally assumed static and associated with large, continental lakes and coastal areas. Temporal changes in the extent of smaller water bodies as small as a few percent of the sensor footprint size, however, can cause significant and dynamic biases. We analysed the influence of such small open water bodies on near-surface soil moisture products derived from actual (non-synthetic) data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) for three areas in Oklahoma, USA. Differences between on-ground observations, model estimates and AMSR-E retrievals were related to dynamic estimates of open water fraction, one retrieved from a global daily record based on higher frequency AMSR-E data, a second derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) and a third through inversion of the radiative transfer model, used to retrieve soil moisture. The comparison demonstrates the presence of relatively small areas (<0.05) of open water in or near the sensor footprint, possibly in combination with increased, below-critical vegetation density conditions (optical density <0.8), which contribute to seasonally varying biases in excess of 0.2 (m3 m−3) soil water content. These errors need to be addressed, either through elimination or accurate characterisation, if the soil moisture retrievals are to be used effectively in a data assimilation scheme.

scholarly journals Global climatology and trends in convective environments from ERA5 and rawinsonde data

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mateusz Taszarek ◽  
John T. Allen ◽  
Mattia Marchio ◽  
Harold E. Brooks
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Convective Available Potential Energy ◽  
Global Climate Models ◽  
Convective Precipitation ◽  
The Past ◽  
The Tropics ◽  
Rawinsonde Data

AbstractGlobally, thunderstorms are responsible for a significant fraction of rainfall, and in the mid-latitudes often produce extreme weather, including large hail, tornadoes and damaging winds. Despite this importance, how the global frequency of thunderstorms and their accompanying hazards has changed over the past 4 decades remains unclear. Large-scale diagnostics applied to global climate models have suggested that the frequency of thunderstorms and their intensity is likely to increase in the future. Here, we show that according to ERA5 convective available potential energy (CAPE) and convective precipitation (CP) have decreased over the tropics and subtropics with simultaneous increases in 0–6 km wind shear (BS06). Conversely, rawinsonde observations paint a different picture across the mid-latitudes with increasing CAPE and significant decreases to BS06. Differing trends and disagreement between ERA5 and rawinsondes observed over some regions suggest that results should be interpreted with caution, especially for CAPE and CP across tropics where uncertainty is the highest and reliable long-term rawinsonde observations are missing.

scholarly journals A Unified Convection Scheme (UNICON). Part I: Formulation

2014 ◽  
Vol 71 (11) ◽  
pp. 3902-3930 ◽  
Author(s):  
Sungsu Park
Keyword(s):  
Deep Convection ◽  
Convective Available Potential Energy ◽  
Horizontal Resolution ◽  
Vertical Transport ◽  
Convective Precipitation ◽  
Cold Pool ◽  
Quasi Equilibrium ◽  
Convection Scheme ◽  
Time Step ◽  
Turbulent Eddies

Abstract The author develops a unified convection scheme (UNICON) that parameterizes relative (i.e., with respect to the grid-mean vertical flow) subgrid vertical transport by nonlocal asymmetric turbulent eddies. UNICON is a process-based model of subgrid convective plumes and mesoscale organized flow without relying on any quasi-equilibrium assumptions such as convective available potential energy (CAPE) or convective inhibition (CIN) closures. In combination with a relative subgrid vertical transport scheme by local symmetric turbulent eddies and a grid-scale advection scheme, UNICON simulates vertical transport of water species and conservative scalars without double counting at any horizontal resolution. UNICON simulates all dry–moist, forced–free, and shallow–deep convection within a single framework in a seamless, consistent, and unified way. It diagnoses the vertical profiles of the macrophysics (fractional area, plume radius, and number density) as well as the microphysics (production and evaporation rates of convective precipitation) and the dynamics (mass flux and vertical velocity) of multiple convective updraft and downdraft plumes. UNICON also prognoses subgrid cold pool and mesoscale organized flow within the planetary boundary layer (PBL) that is forced by evaporation of convective precipitation and accompanying convective downdrafts but damped by surface flux and entrainment at the PBL top. The combined subgrid parameterization of diagnostic convective updraft and downdraft plumes, prognostic subgrid mesoscale organized flow, and the feedback among them remedies the weakness of conventional quasi-steady diagnostic plume models—the lack of plume memory across the time step—allowing UNICON to successfully simulate various transitional phenomena associated with convection (e.g., the diurnal cycle of precipitation and the Madden–Julian oscillation).

scholarly journals Stochastorm: A stochastic rainfall simulator for convective storms

2020 ◽  
Author(s):  
Catherine Wilcox ◽  
Claire Aly ◽  
Théo Vischel ◽  
Gérémy Panthou ◽  
Juliette Blanchet ◽  
...  
Keyword(s):  
Impact Analysis ◽  
Extreme Values ◽  
Rain Gauge ◽  
Convective Precipitation ◽  
Precipitation Event ◽  
Storm Event ◽  
Spatial And Temporal Scales ◽  
Convective Storms ◽  
Distribution Parameters ◽  
Temporal Disaggregation

AbstractStochastic rainfall generators aim to reproduce the main statistical features of rainfall at small spatial and temporal scales. The simulated synthetic rainfall series are recognized as suitable for use with impact analysis in water, agricultural, and ecological management. Convection-driven precipitation, dominant in certain regions of the world such as the intertropical belt regions, presents properties that require specific consideration when modeling: (i) strong rainfall intermittency, (ii) high variability of intensities within storms, (iii) strong spatiotemporal correlation of intensities, and (iv) marked seasonality of storm properties. In this article, improvements for an existing statistico-dynamic rainfall generator that models convective storms are presented. Notable novelties include (i) the ability to model precipitation event timing, (ii) an improved temporal disaggregation scheme representing the rainfall distribution at sub-event scales, and (iii) using covariates to reflect seasonal changes in precipitation occurrence and marginal distribution parameters. Extreme values are explicitly considered in the distribution of storm event intensities. The simulator is calibrated and validated using 28 years of five-minute precipitation data from the 30 rain gauge AMMA-CATCH network in the Sahelian region of southwest Niger. Both large propagative systems and smaller local convective precipitation are generated. Results show that simulator improvements coherently represent the local climatology. The simulator can generate scenarios for impact studies with accurate representation of convective precipitation characteristics.

scholarly journals Ist Wasserbau auch eine Frage der Ästhetik? | Is hydraulic engineering a question of aesthetics?

2008 ◽  
Vol 159 (7) ◽  
pp. 205-208
Author(s):  
Gianni Paravicini
Keyword(s):  
Open Water ◽  
Hydraulic Engineering ◽  
Water Bodies ◽  
Ecological Value ◽  
The Aesthetic ◽  
Bodies Of Water

There is much extended literature about classic technical hydraulic engineering and about the revitalization of bodies of water. This article deals with a third component, which has received little attention by the engineers. The author pleads for more aesthetic in hydraulic engineering, in particular in populated areas where many people use the open water bodies for recreation. It is shown that more aesthetic in hydrologic engineering often also leads to an increased ecological value. With hydraulic constructions in the canton of Lueerne, possible creative elements for the aesthetic and ecological revaluation of the course of creeks are discussed.

Change in thunderstorm activity in a projected warmer future climate over Bangladesh

2021 ◽  
Author(s):  
Shahana Akter Esha ◽  
Nasreen Jahan
Keyword(s):  
Climate Model ◽  
Convective Available Potential Energy ◽  
Thunderstorm Activity ◽  
Future Climate ◽  
Convective Precipitation ◽  
Severe Thunderstorms ◽  
Wide Range ◽  
The Future ◽  
Rcp 8.5 ◽  
Increasing Risk

&lt;p&gt;Thunderstorms can have a wide range of impacts on modern societies and their assets. Severe thunderstorms associated with thunder squall, hail, tornado, and lightning cause extensive damage and losses to lives, especially in the densely populated sub-tropical countries like Bangladesh. In this study the future changes in thunderstorm conducive environments, in terms convective available potential energy (CAPE), have been assessed under the RCP 8.5 scenario for the selected major cities of Bangladesh. Results show an increase in CAPE for all the selected cities and in the range of 44%&amp;#8211;106%. Later, a statistical thunderstorm frequency prediction model has been developed based on CAPE and convective precipitation and the probable scenario of thunderstorm frequency in the 21st century under future climate has been projected. The simulations were carried out for three different time slices (Early, Mid and Late 21&lt;sup&gt;st&lt;/sup&gt; century) with CMCC-CM (Centro Euro-Mediterraneo per Cambiamenti Climatici Climate Model) model data. The future projection of thunderstorm shows an increase in thunderstorm frequency for all the season in a warmer future climate. But pre-monsoon and monsoon are found to be the most thunderstorm frequent season. Given the substantial damage from severe thunderstorms in the current climate, such increases imply an increasing risk of thunderstorm-related damage in this disaster-prone region of the world.&lt;/p&gt;

A multi-temporal remote sensing approach for monitoring changes in spatial extent of freshwater lake of Deepor Beel Ramsar Site, a major wetland of Assam

2011 ◽  
Vol 5 ◽  
pp. 40-47 ◽  
Author(s):  
Jyotishman Deka ◽  
Om Prakash Tripathi ◽  
Mohammad Latif Khan
Keyword(s):  
Open Water ◽  
Management Plan ◽  
Rate Of Change ◽  
Freshwater Lake ◽  
Landsat Tm ◽  
Water Bodies ◽  
Food Storage ◽  
Data Mapping ◽  
Wetland Ecosystem ◽  
Rapid Urbanization

Sustainability of wetland ecosystem is necessary for various important functions such as food storage, water quality continuation and providing habitat for different species of flora and fauna. Hence, an inventory of wetlands of any region is a pre-requisite for their conservation and management. This study has been carried out to delineate the change in freshwater lake of ‘Deepor Beel’ wetland of Assam, India, using LANDSAT TM data. Field observation shows that the ecosystem is facing both natural as well as anthropogenic threats. Rapid urbanization, Illegal settlements, industries, invasive species (Eichhornia crassipes) are the major cause of this wetland decline. It has been found that massive decline occurred between the period 1991 to 2001 i.e., 1.891 sq.km which was at the rate of -0.171 per year where as the decline between the period 2001 to 2010 was found to be 1.013 sq. km which was at a rate of -0.101. The total area of open water bodies has decreased by 2.904 sq. km from 1991 to 2010 i.e. 59.19%. Thus the overall rate of change in the water bodies from 1991 to 2010 to other land use categories was found to be -0.145. Hence the study reveals the potentiality of Landsat TM data mapping the change in the wetland ecosystem. It is further hoped that the study will have high utility in preparing management plan for conservation of this ecosystem. Keywords: Wetland; Landsat TM; Thresholding; density sliceDOI: http://dx.doi.org/10.3126/jowe.v5i0.4696 J Wet Eco 2011 (5): 40-47

scholarly journals Spatial and Temporal Dynamics of Urban Wetlands in an Indian Megacity over the Past 50 Years

2020 ◽  
Vol 12 (4) ◽  
pp. 662 ◽  
Author(s):  
Katja Brinkmann ◽  
Ellen Hoffmann ◽  
Andreas Buerkert
Keyword(s):  
Land Cover ◽  
Urban Areas ◽  
Temporal Dynamics ◽  
Open Water ◽  
Water Bodies ◽  
Annual Rainfall ◽  
Urban Wetlands ◽  
Landsat Images ◽  
Urban District ◽  
Wetland Area

Asian megacities have attracted much scientific attention in the context of global urbanization, but few quantitative studies analyze wetland transformation in the rural–urban interface. With its rampant growth and transformation from a tree-lined “Garden City” to a busy megalopolis with often-blocked highways and large built-up areas, Bengaluru (Karnataka, S-India) is a good example for assessing how urbanization has led to the acute degradation of wetlands. We therefore investigated long-term land cover and wetland changes from 1965 to 2018 based on an object-based classification of multi-temporal Corona and Landsat images. To quantify and compare the dynamics of open water surfaces and vegetation, we defined the potential wetland areas (PWA) along the rural–urban gradient and linked our analyses to an index describing the degree of urbanization (survey stratification index (SSI)). During the five decades studied, built-up areas in the Bengaluru Urban district increased ten-fold, with the highest growth rate from 2014 to 2018 (+ 8% annual change). Patches of lake wetlands were highly dynamic in space and time, partly reflecting highly variable annual rainfall patterns ranging from 501 mm in 1965 to 1374 mm in 2005 and monsoon-driven alterations in the hydrologic regime. While water bodies and flooded areas shrunk from 64 km2 in 1965 to 55 km2 in 2018, in 1965, the total rural wetland area with an SSI > 0.5 was twice as high as in 2018. The rural–urban land cover pattern within potential wetland areas changed drastically during this period. This is reflected, for example, by a four-fold increase in the wetland area with an SSI of 0.3, as compared to a decline by 43% in wetland area with an SSI of 0.8. While, in urban areas, wetlands were mostly lost to construction, in areas with a rural character, open water bodies were mainly transformed into green space. The detected changes in urban wetlands were likely accompanied by ecological regime changes, triggering deteriorations in ecosystem services (ESS) which merit further research.

Sign in / Sign up

Export Citation Format

Share Document