Influences of Lake Malawi on the spatial and diurnal variability of local precipitation

Koseki, Shunya; Mooney, Priscilla A.

doi:10.5194/hess-23-2795-2019

Cited by 6 publications

(5 citation statements)

References 55 publications

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“…Figures 6 and 7 show shifts in precipitation and temperature maxima which are associated with a very different characteristic time for the heat fluxes, suggesting that in the simulations with a lake system the valley-lake breeze commences later than it does when no lake is present. Additionally, lake breeze plus mountain-valley breeze modify the convergence zones, where moisture fluxes with background water vapor favor precipitation to the southwest [14,15,46].…”

Section: Discussionmentioning

confidence: 99%

Impacts of the Desiccated Lake System on Precipitation in the Basin of Mexico City

et al. 2019

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Mexico City constitutes one of the largest concentrations of population on the planet and is settled in a valley that, before the 16th century, had a lake system. The lakes were desiccated artificially, and currently, only small lakes remain. The impact of the lake system desiccation on precipitation was studied by performing numerical experiments: with the ancient lake system and without it. The experiments were carried out with the Weather Research and Forecasting (WRF) model coupled with a lake model for two months, using identical initial and boundary conditions, where only the system and lake physics were changed. The mean daily accumulated precipitation reduced when the system was removed. Additionally, the hourly distribution of rainfall changed from a relatively small diurnal variability when there was a lake system to a larger variability with a peak in the afternoon when the system was removed. Extreme precipitation events became more intense in the simulations with lakes. When the lakes were removed, the diurnal temperature range increased, and the boundary layer height became more variable, with a higher daily maximum. The results presented here show that the WRF-Lake model leads to opposite results compared to those with a non-coupled lake.

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Section: Discussionmentioning

confidence: 99%

Impacts of the Desiccated Lake System on Precipitation in the Basin of Mexico City

et al. 2019

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“…The ECOCLIMAP-II lake cover scheme provides binary information on the presence (or lack thereof) of a lake in the pixel. No other information is provided, and thus lake cover information is completed with the Global Lake DataBase (GLDB, Kourzeneva et al, 2012;Choulga et al, 2014), which has gridded in situ and estimated lake mean depth at 1 km resolution globally. This global database has been developed to gather lake information and retrieve mean depth information for numerical weather prediction.…”

Section: Isba-ctrip Systemmentioning

confidence: 99%

Parametrization of a lake water dynamics model MLake in the ISBA-CTRIP land surface system (SURFEX v8.1)

et al. 2021

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Abstract. Lakes are of fundamental importance in the Earth system as they support essential environmental and economic services, such as freshwater supply. Streamflow variability and temporal evolution are impacted by the presence of lakes in the river network; therefore, any change in the lake state can induce a modification of the regional hydrological regime. Despite the importance of the impact of lakes on hydrological fluxes and the water balance, a representation of the mass budget is generally not included in climate models and global-scale hydrological modeling platforms. The goal of this study is to introduce a new lake mass module, MLake (Mass-Lake model), into the river-routing model CTRIP to resolve the specific mass balance of open-water bodies. Based on the inherent CTRIP parameters, the development of the non-calibrated MLake model was introduced to examine the influence of such hydrological buffer areas on global-scale river-routing performance. In the current study, an offline evaluation was performed for four river networks using a set of state-of-the-art quality atmospheric forcings and a combination of in situ and satellite measurements for river discharge and lake level observations. The results reveal a general improvement in CTRIP-simulated discharge and its variability, while also generating realistic lake level variations. MLake produces more realistic streamflows both in terms of daily and seasonal correlation. Excluding the specific case of Lake Victoria having low performances, the mean skill score of Kling–Gupta efficiency (KGE) is 0.41 while the normalized information contribution (NIC) shows a mean improvement of 0.56 (ranging from 0.15 to 0.94). Streamflow results are spatially scale-dependent, with better scores associated with larger lakes and increased sensitivity to the width of the lake outlet. Regarding lake level variations, results indicate a good agreement between observations and simulations with a mean correlation of 0.56 (ranging from 0.07 to 0.92) which is linked to the capability of the model to retrieve seasonal variations. Discrepancies in the results are mainly explained by the anthropization of the selected lakes, which introduces high-frequency variations in both streamflows and lake levels that degraded the scores. Anthropization effects are prevalent in most of the lakes studied, but they are predominant for Lake Victoria and are the main cause for relatively low statistical scores for the Nile River However, results on the Angara and the Neva rivers also depend on the inherent gap of ISBA-CTRIP process representation, which relies on further development such as the partitioned energy budget between the snow and the canopy over a boreal zone. The study is a first step towards a global coupled land system that will help to qualitatively assess the evolution of future global water resources, leading to improvements in flood risk and drought forecasting.

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“…Unlike the Great Lakes, low‐latitude lakes have relatively higher temperatures than surrounding land and tend to increase precipitation in summer rainy season (Dutra et al., 2010). Because of the intense evaporation from water bodies (Gat & Matsui, 1991; Nicholson & Yin, 2002), tropical lakes lead to significant precipitation increases over the lake and adjacent areas due to continuous enhancements of water vapor mixing ratio, especially during nighttime (Diallo et al., 2018; Koseki & Mooney, 2019). In addition, the warm (cold) lake surface during nighttime (daytime) excites a large number of thunderstorms over Lake Victoria (surrounding land; Thiery et al., 2016).…”

Section: Introductionmentioning

confidence: 99%

Effects of Lake Nam Co and Surrounding Terrain on Extreme Precipitation Over Nam Co Basin, Tibetan Plateau: A Case Study

Zhao

Huang

et al. 2022

JGR Atmospheres

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Thousands of lakes and complex topography on Tibetan Plateau (TP) have important impacts on the local weather and climate, especially extreme weather events. In this study, the Weather Research and Forecasting model was adopted to quantify the impacts of Lake Nam Co (LNC) and surrounding topography on the extreme snowfall event over Nam Co basin on 24 October 2006 based on numerical experiments. The accumulated precipitation of 12 hr in this event is characterized by a maximum precipitation center with an intensity exceeding 20 mm over eastern LNC and downwind regions. Results show that the precipitation regionally averaged over eastern LNC and downstream regions can be reduced by 53%, 26%, and 68% when LNC, surrounding terrain, and both of them are absent, respectively, suggesting that LNC plays a dominant role in the formation of this event while the surrounding mountains further amplify the lake effect precipitation/snow over the downwind of LNC. Mechanism analysis indicates that the low‐level convective instability and water vapor convergence induced by LNC are essential for the formation of this extreme snowfall event, while the wind deflection and topographic lifting further strengthen the precipitation over the downwind of LNC and shift the snow belt distribution. This study is not only important to deepen the understanding of the complex interactions between the lake and orography and their combined influences on regional extreme precipitation, but also helpful for further improving the refined forecasting of the extreme precipitation induced by the lake and surrounding terrain in other regions over TP.

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Influences of Lake Malawi on the spatial and diurnal variability of local precipitation

Cited by 6 publications

References 55 publications

Impacts of the Desiccated Lake System on Precipitation in the Basin of Mexico City

Impacts of the Desiccated Lake System on Precipitation in the Basin of Mexico City

Parametrization of a lake water dynamics model MLake in the ISBA-CTRIP land surface system (SURFEX v8.1)

Effects of Lake Nam Co and Surrounding Terrain on Extreme Precipitation Over Nam Co Basin, Tibetan Plateau: A Case Study

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