scholarly journals High-Resolution WRF Simulation of Extreme Heat Events in Eastern China: Large Sensitivity to Land Surface Schemes

2021 ◽  
Vol 9 ◽  
Author(s):  
Wenjian Hua ◽  
Xuan Dong ◽  
Qingyuan Liu ◽  
Liming Zhou ◽  
Haishan Chen ◽  
...  
Keyword(s):  
High Resolution ◽  
Land Surface ◽  
Eastern China ◽  
Extreme Heat ◽  
Surface Processes ◽  
Energy Fluxes ◽  
Land Surface Processes ◽  
Extreme Heat Events ◽  
The Relationship ◽  
Heat Events

Regional climate models with high-resolution simulation are particularly useful for providing a detailed representation of land surface processes, and for studying the relationship between land surface processes and heat events. However, large differences and uncertainties exist among different land surface schemes (LSSs). This study comprehensively assesses the sensitivity to different LSSs based on two extreme heat events in eastern China using the Weather Research and Forecasting (WRF) model. Among the five LSSs (i.e., 5TD, CLM4, Noah, Noah-MP and RUC), Noah is closest to observations in reproducing the temperatures and energy fluxes for both two heat events. The modeled warm biases result mainly from the underestimation of evapotranspirative cooling. Our results show that how each LSS partitions the evapotranspiration (ET) and sensible heat largely determines the relationship between the temperature and turbulent fluxes. Although the simulated two extreme heat events manifest similar biases in the temperatures and energy fluxes, the land surface responses (ET and soil moisture) are different.

scholarly journals Interdecadal Variations of Persistent Extreme Heat Events in Eastern China Under Global Warming

2021 ◽  
Author(s):  
Naihui Zang ◽  
Junhu Zhao ◽  
Pengcheng Yan ◽  
Han Zhang ◽  
Shankai Tang ◽  
...  
Keyword(s):  
Global Warming ◽  
21St Century ◽  
South China ◽  
North China ◽  
Eastern China ◽  
Extreme Heat ◽  
Maximum Temperature ◽  
Extreme Heat Events ◽  
June July ◽  
Heat Events

Abstract Persistent extreme heat events (PEHEs) exert a more negative impact on society, including agriculture, plant phenology, power production and human health, compared to general EHEs. The temporal and spatial characteristics of summer PEHEs in eastern China were analysed based on a daily maximum temperature dataset from 759 stations over the period of 1961–2018. The results show the following: Persistent distributions of PEHEs show that they are characterized by an exponential decay with a drop in the decay rate. In terms of spatial distribution, there is an apparent regional difference in the duration of PEHEs. North China is dominated by multi-frequency and short-duration EHEs, while South China is the opposite. PEHEs in North China and the Huanghuai region mainly occur in June-July but mostly in July and August in South China. Strongly responding to global warming, the frequency and duration of PEHEs in North China have increased since the 1990s. However, the frequency of PEHEs in North China and the Huanghuai region has shown opposite trends in June-July since the beginning of the 21st century. Affected by the atmospheric circulations, the regional differences in PEHE frequency are also apparent. Since the beginning of the 21st century, the PEHEs in North China and the Huanghuai area have shown an increasing trend in August. The short-term PEHEs in the middle and lower reaches of the Yangtze River and South China increased rapidly in the 2000s, while long-term PEHEs increased in the 2010s. This study implies that attention should be paid to not only the frequency of EH days but also to the persistence of EHE which is a key characteristic of damaging EH.

Study of Land Surface feedback in catalysing the intensity and duration of Heatwave over Indian subcontinent

2020 ◽  
Author(s):  
Shashi Gaurav Kumar ◽  
Ajanta Goswami
Keyword(s):  
Heat Flux ◽  
Soil Moisture ◽  
Solar Radiation ◽  
Land Surface ◽  
Indian Subcontinent ◽  
Extreme Heat ◽  
Clear Sky ◽  
Extreme Heat Events ◽  
Drying Up ◽  
Heat Events

<p>Extreme heat events are rising in nature over the Indian subcontinent under the stressed environmental conditions. Unprecedented event of extreme heat is threatening our socio-economic and ecosystem. April marks the start of summer with a clear sky; agricultural harvesting exposes the large land surface to solar heating, so the drying up of the surface causing loss of soil moisture and vegetations. Temperature anomalies become high during May and June, signifying possible role play local land-surface-atmosphere feedbacks involving dried soils in driving the heat extreme. Thus, the study of extreme heat and surface feedback process is conducted using a combination of ERA5 reanalysis data, GLDAS Noah Land Surface Model data, satellite-based observations (TRMM and MODIS), and in-situ India Metrological Department datasets. To address the bias present in datasets, we make use of IMD Datasets for bias correction. We use 2m air temperature to define the extreme heat events as per the IMD definition for the heatwave from 2001 to 2019. Parameters like surface net solar and thermal radiation and (also, clear sky) heat flux, total precipitation, land surface temperature, land use type and vegetation cover, soil moisture used to study the details of land surface conditions during the heatwave events. The examination of the above datasets in space-time provided the general view of heatwaves and suggest that late April and early May with clear sky increased net solar radiation started drying up the surface. Late May and early June with a clear sky and positive net solar radiation anomaly with positive heat flux anomaly and lack of soil moisture and rainfall developed local forcing on air temperature that catalyzed the heatwave events in terms of intensity and duration. The above conclusion is supported by the satellite-derived land surface temperature and heat flux. The results obtained establish the link between the local surface feedback and extreme heat events during the summer over the Indian subcontinent and can enhance in a dry environment with the large agricultural field with no standing crop barren land or land with dead or no shrubs over India leaving northern Himalayan part.</p>

Sensitivity of high-resolution Arctic regional climate model projections to different implementations of land surface processes

2011 ◽  
Vol 111 (2) ◽  
pp. 197-214 ◽  
Author(s):  
Heidrun Matthes ◽  
Annette Rinke ◽  
Paul A. Miller ◽  
Peter Kuhry ◽  
Klaus Dethloff ◽  
...  
Keyword(s):  
High Resolution ◽  
Regional Climate Model ◽  
Land Surface ◽  
Climate Model ◽  
Regional Climate ◽  
Surface Processes ◽  
Land Surface Processes

scholarly journals Interdecadal variations of persistent extreme heat events in eastern China under global warming

2021 ◽  
Author(s):  
Naihui Zang ◽  
Junhu Zhao ◽  
Pengcheng Yan ◽  
Han Zhang ◽  
Shankai Tang ◽  
...  
Keyword(s):  
Global Warming ◽  
Eastern China ◽  
Extreme Heat ◽  
Extreme Heat Events ◽  
Heat Events

scholarly journals Development of a Submonthly Temperature Product to Monitor Near-Real-Time Climate Conditions and Assess Long-Term Heat Events in the United States

2019 ◽  
Vol 58 (12) ◽  
pp. 2653-2674 ◽  
Author(s):  
Jared Rennie ◽  
Jesse E. Bell ◽  
Kenneth E. Kunkel ◽  
Stephanie Herring ◽  
Heidi Cullen ◽  
...  
Keyword(s):  
United States ◽  
Land Surface ◽  
Minimum Temperature ◽  
Regional Analysis ◽  
The United States ◽  
Extreme Heat ◽  
Climate Conditions ◽  
Extreme Heat Events ◽  
Heat Event ◽  
Heat Events

AbstractLand surface air temperature products have been essential for monitoring the evolution of the climate system. Before a temperature dataset is included in such analyses, it is important that nonclimatic influences be removed or changed so that the dataset is considered to be homogenous. These inhomogeneities include changes in station location, instrumentation, and observing practices. Many homogenized products exist on the monthly time scale, but few daily and weekly products exist. Recently, a submonthly homogenized dataset has been developed using data and software from NOAA’s National Centers for Environmental Information. Homogeneous daily data are useful for identification and attribution of extreme heat events. Projections of increasing temperatures are expected to result in corresponding increases in the frequency, duration, and intensity of such events. It is also established that heat events can have significant public health impacts, including increases in mortality and morbidity. The method to identify extreme heat events using daily homogeneous temperature data is described and used to develop a climatology of heat event onset, length, and severity. This climatology encompasses nearly 3000 extreme maximum and minimum temperature events across the United States since 1901. A sizeable number of events occurred during the Dust Bowl period of the 1930s; however, trend analysis shows an increase in heat event number and length since 1951. Overnight extreme minimum temperature events are increasing more than daytime maximum temperatures, and regional analysis shows that events are becoming much more prevalent in the western and southeastern parts of the United States.

scholarly journals A subbasin-based framework to represent land surface processes in an Earth System Model

2013 ◽  
Vol 6 (2) ◽  
pp. 2699-2730 ◽  
Author(s):  
H.-Y. Li ◽  
M. Huang ◽  
T. Tesfa ◽  
Y. Ke ◽  
Y. Sun ◽  
...  
Keyword(s):  
High Resolution ◽  
Land Surface ◽  
System Model ◽  
Surface Processes ◽  
Earth System ◽  
Land Surface Models ◽  
Land Surface Processes ◽  
Surface Models ◽  
Earth System Models ◽  
Grid Based

Abstract. Realistically representing spatial heterogeneity and lateral land surface processes within and between modeling units in earth system models is important because of their implications to surface energy and water exchanges. The traditional approach of using regular grids as computational units in land surface models and earth system models may lead to inadequate representation of subgrid heterogeneity and lateral movements of water, energy and carbon fluxes, especially when the grid resolution increases. Here a new subbasin-based framework is introduced in the Community Land Model (CLM), which is the land component of the Community Earth System Model (CESM). Local processes are represented assuming each subbasin as a grid cell on a pseudo grid matrix with no significant modifications to the existing CLM modeling structure. Lateral routing of water within and between subbasins is simulated with the subbasin version of a recently-developed physically based routing model, Model for Scale Adaptive River Routing (MOSART). As an illustration, this new framework is implemented in the topographically diverse region of the US Pacific Northwest. The modeling units (subbasins) are delineated from high-resolution Digital Elevation Models (DEMs) while atmospheric forcing and surface parameters are remapped from the corresponding high resolution datasets. The impacts of this representation on simulating hydrologic processes are explored by comparing it with the default (grid-based) CLM representation. In addition, the effects of DEM resolution on parameterizing topography and the subsequent effects on runoff processes are investigated. Limited model evaluation and comparison showed that small difference between the averaged forcing can lead to more significant difference in the simulated runoff and streamflow because of nonlinear lateral processes. Topographic indices derived from high resolution DEMs may not improve the overall water balance, but affect the partitioning between surface and subsurface runoff. More systematic analyses are needed to determine the relative merits of the subbasin representation compared to the commonly used grid-based representation, especially when land surface models are approaching higher resolutions.

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