scholarly journals The impact of two land‐surface schemes on the characteristics of summer precipitation over East Asia from the RegCM4 simulations

2014 ◽  
Vol 34 (15) ◽  
pp. 3986-3997 ◽  
Author(s):  
Suchul Kang ◽  
Eun‐Soon Im ◽  
Joong‐Bae Ahn
Keyword(s):  
East Asia ◽  
Land Surface ◽  
Summer Precipitation ◽  
The Impact

Irrigation in JULES Land-Only Simulations over South and East Asia

2021 ◽  
Author(s):  
Markus Todt ◽  
Pier Luigi Vidale ◽  
Patrick C. McGuire ◽  
Omar V. Müller
Keyword(s):  
Soil Moisture ◽  
East Asia ◽  
Land Surface ◽  
River Flow ◽  
Heat Fluxes ◽  
Global Climate Models ◽  
Irrigated Agriculture ◽  
Irrigation Season ◽  
Irrigation Scheme ◽  
The Impact

<p>Capturing soil moisture-atmosphere feedbacks in a weather or climate model requires realistic simulation of various land surface processes. However, irrigation and other water management methods are still missing in most global climate models today, despite irrigated agriculture being the dominant land use in parts of Asia. In this study, we test the irrigation scheme available in the land model JULES (Joint UK Land Environment Simulator) by running land-only simulations over South and East Asia driven by WFDEI (WATCH Forcing Data ERA-Interim) forcing data. Irrigation in JULES is applied on a daily basis by replenishing soil moisture in the upper soil layers to field capacity, and we use a version of the irrigation scheme that extracts water for irrigation from groundwater and rivers, which physically limits the amount of irrigation that can be applied. We prescribe irrigation for C3 grasses in order to simulate the effects of agriculture, albeit retaining the simpler, widely used 5-PFT (plant functional type) configuration in JULES. Irrigation generally increases soil moisture and evapotranspiration, which results in increasing latent heat fluxes and decreasing sensible heat fluxes. Comparison with combined observational/machine-learning products for turbulent fluxes shows that while irrigation can reduce biases, other biases in JULES, unrelated to irrigation, are larger than improvements due to the inclusion of irrigation. Irrigation also affects water fluxes within the soil, e.g. runoff and drainage into the groundwater level, as well as soil moisture outside of the irrigation season. We find that the irrigation scheme, at least in the uncoupled land-atmosphere setting, can rapidly deplete groundwater to the point that river flow becomes the main source of irrigation (over the North China Plain and the Indus region) and can have the counterintuitive effect of decreasing annual average soil moisture (over the Ganges plain). Subsequently, we will explore the impact of irrigation on regional climate by conducting coupled land-atmosphere simulations.</p>

scholarly journals The impact of clouds, land use and snow cover on climate in the Canadian Prairies

2016 ◽  
Vol 13 ◽  
pp. 37-42 ◽  
Author(s):  
Alan K. Betts ◽  
Raymond L. Desjardins ◽  
Devon E. Worth
Keyword(s):  
Land Use ◽  
Snow Cover ◽  
Air Temperature ◽  
Land Surface ◽  
Agricultural Land ◽  
Summer Precipitation ◽  
Climate Data ◽  
Canadian Prairies ◽  
Cloud Forcing ◽  
The Impact

Abstract. This study uses 55 years of hourly observations of air temperature, relative humidity, daily precipitation, snow cover and cloud cover from 15 climate stations across the Canadian Prairies to analyze biosphere-atmosphere interactions. We will provide examples of the coupling between climate, snow cover, clouds, and land use. Snow cover acts as a fast climate switch. With the first snow fall, air temperature falls by 10 °C, and a similar increase in temperature occurs with snow melt. Climatologically, days with snow cover are 10 °C cooler than days with no snow cover in Alberta. However the interannual variability has a larger range, so that for every 10 % decrease in days with snow cover, the mean October to April climate is warmer by 1.4 to 1.5 °C. Snow cover also transforms the coupling between clouds and the diurnal cycle of air temperature from a boundary layer regime dominated by shortwave cloud forcing in the warm season to one dominated by longwave cloud forcing with snow cover. Changing agricultural land use in the past thirty years, specifically the reduction of summer fallowing, has cooled and moistened the growing season climate and increased summer precipitation. These hourly climate data provide a solid observational basis for understanding land surface coupling, which can be used to improve the representation of clouds and land-surface processes in atmospheric models.

scholarly journals Improvement in the Prediction of Summer Precipitation in the North China−Hetao Region Using the Tropospheric Temperature Over the Tibetan Plateau in Spring

2021 ◽  
Vol 9 ◽  
Author(s):  
Dan Chen ◽  
Sulan Nan ◽  
Ge Liu ◽  
Changyan Zhou ◽  
Renrui Shi ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
East Asia ◽  
North China ◽  
Summer Precipitation ◽  
Asia Pacific ◽  
The Tibetan Plateau ◽  
Tropospheric Temperature ◽  
The North ◽  
The Impact ◽  
The Relationship

We investigated the relationship between the spring tropospheric temperature over the Tibetan Plateau (TPT) and summer precipitation in eastern China on an interannual timescale using the monthly mean ERA-Interim reanalysis dataset, the HadISST dataset and the daily mean precipitation dataset for China. We found that there is a significant positive correlation between the spring TPT and summer precipitation in the North China−Hetao region. The relationship is manifested in the context of the East Asia–Pacific pattern teleconnection. In the high spring TPT index years, the geopotential height anomalies over East Asia and the western North Pacific present a negative phase of the East Asia–Pacific pattern teleconnection in the subsequent summer. This circulation pattern is beneficial for the water vapor transport from the western Pacific to inland, which further transport to the North China−Hetao region from the Yangtze River–Yellow rivers region. Anomalous upward motion occurs in the North China–Hetao region, which increases precipitation. The East Asian subtropical westerly jet shifts further north and the South Asian high weakens and shrinks westward. These conditions all favor an increase in precipitation over the North China–Hetao region. The spring TPT plays an important part in the prediction of summer precipitation in the North China−Hetao region. The improvement in the use of the spring TPT to predict summer precipitation in the North China–Hetao region is examined by comparing the prediction equations with and without the prediction factor of the spring TPT on the basis of the sea surface temperatures in key regions. After considering the impact of the spring TPT, the explanatory variance of the prediction equation for precipitation in the North China–Hetao region increases by 17.3%.

Diverse Regional Sensitivity of Summer Precipitation in East Asia to Ice Volume, CO2 and Astronomical Forcing

2021 ◽  
Author(s):  
Anqi Lyu ◽  
Qiuzhen Yin ◽  
Michel Crucifix ◽  
Youbin Sun
Keyword(s):  
East Asia ◽  
Asian Summer Monsoon ◽  
Ice Sheets ◽  
Summer Precipitation ◽  
Relative Role ◽  
The South ◽  
Ice Volume ◽  
The North ◽  
Astronomical Forcing ◽  
The Impact

<p>The East Asian summer monsoon (EASM) is an important component of the climate system and it influences about one-third of the world’s population. Numerous paleoclimate records and climate simulations have been used to study its long-term evolution and response to different forcings. The strong regional dependence of the EASM variation questions the relative role of ice sheets and insolation on the EASM precipitation in different sub-regions in East Asia. A Gaussian emulator, which was generated and calibrated by interpolating the outputs of 61 snapshot simulations performed with the model HadCM3, is used to quantitatively assess how astronomical forcing, CO<sub>2</sub> and northern hemisphere ice sheets affect the variation of the summer precipitation over the last 800 ky. Our results show that in the north of 25°N of the EASM domain, the variation of the summer precipitation is dominated by precession and insolation. This leads to strong 23-ky cycles in the summer precipitation. However, in the southern part (south of 25°N), the impact of ice volume becomes more important, leading to strong 100-ky cycles. Ice sheets influence the summer precipitation in the south mainly through its control on the location of the Intertropical Convergence Zone (ITCZ) which is very sensitive to ice volume. ITCZ is shifted significantly to the south under large ice sheets conditions. Therefore, the region under control of the ITCZ is more sensitive to the influence of ice volume than other regions. Our results also show that obliquity and CO<sub>2</sub> have relatively small effect on the summer precipitation as compared to precession and ice sheets.</p>

scholarly journals A 10 km North American Precipitation and Land Surface Reanalysis Based on the GEM Atmospheric Model

2021 ◽  
Author(s):  
Nicolas Gasset ◽  
Vincent Fortin ◽  
Milena Dimitrijevic ◽  
Marco Carrera ◽  
Bernard Bilodeau ◽  
...  
Keyword(s):  
North American ◽  
Land Surface ◽  
Lower Troposphere ◽  
Summer Precipitation ◽  
Atmospheric Model ◽  
Dew Point ◽  
Land Data Assimilation ◽  
Precipitation Analysis ◽  
Land Data Assimilation System ◽  
The Impact

Abstract. Environment and Climate Change Canada has initiated the production of a 1980–2018, 10 km, North American precipitation and surface reanalysis. ERA-Interim is used to initialize the Global Deterministic Reforecast System (GDRS) at a 39 km resolution. Its output is then dynamically downscaled to 10 km by the Regional Deterministic Reforecast System (RDRS). Coupled with the RDRS, the Canadian Land Data Assimilation System (CaLDAS) and Precipitation Analysis (CaPA) are used to produce surface and precipitation analyses. All systems used are close to operational model versions and configurations. In this study, a 7-year sample of the reanalysis (2011–2017) is evaluated. Verification results show that the skill of the RDRS is stable over time, and equivalent to that of the current operational system. The impact of the coupling between RDRS and CaLDAS is explored using an early version of the reanalysis system which was run at 15 km resolution for the period 2010–2014, with and without the use of CaLDAS. Significant improvements are observed with CaLDAS in the lower troposphere and surface layer, especially for the 850 hPa dew point and absolute temperatures in summer. Precipitation is further improved through an offline precipitation analysis which allows the assimilation of additional observations of 24-h precipitation totals. The final dataset should be of particular interest for hydrological applications focusing on trans-boundary and northern watersheds, where existing products often show discontinuities at the border and assimilate very few – if any – precipitation observations.

scholarly journals The Continental-Scale Soil-Moisture Precipitation Feedback in Europe with Parameterized and Explicit Convection

2021 ◽  
pp. 1-56
Author(s):  
David Leutwyler ◽  
Adel Imamovic ◽  
Christoph Schär
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Climate Model ◽  
Regional Climate ◽  
Summer Precipitation ◽  
Positive Sign ◽  
Precipitation Frequency ◽  
Continental Scale ◽  
The Impact ◽  
Precipitation Events

AbstractSoil moisture atmosphere interactions are key elements of the regional climate system. There is a well-founded hope that a more accurate representation of the soil moisture-precipitation feedback would improve the simulation of summer precipitation on daily to seasonal, to climate time scales. However, uncertainties have persistently remained as the simulated feedback is strongly sensitive to the model representation of deep convection. Here we assess the feedback representation using a GPU-accelerated version of the regional climate model COSMO. We simulate and compare the impact of continental-scale springtime soil-moisture anomalies on summer precipitation at convection-resolving (2.2 km) and convection-parameterizing resolution (12 km). We conduct re-analysis-driven simulations of 10 summer seasons (1999-2008) in continental Europe. While both simulations qualitatively agree on a positive sign of soil moisture-induced precipitation, they strongly differ in precipitation frequency: When convection is parameterized, wetter soil predominantly leads to more frequent precipitation events, and when convection is treated explicitly, they primarily become more intense. The results indicate that the sensitivity to soil moisture is stronger with parameterized convection, suggesting that the land surface-atmosphere coupling may be overestimated. In addition, the feedback’s sensitivity in complex terrain is assessed for soil perturbations of different horizontal scales. The convection-resolving simulations confirm a negative feedback for sub-continental soil moisture anomalies, which manifests itself in a local decrease of wet-hour frequency. However, the intensity feedback reinforces precipitation events at the same time (positive feedback). The two processes are represented differently in simulations with explicit and parameterized convection, explaining much of the difference between the two simulations.

Impact of land use land cover change on East Asia

2020 ◽  
Author(s):  
Ui-Yong Byun ◽  
Eun-Chul Chang
Keyword(s):  
Land Use ◽  
Land Cover ◽  
East Asia ◽  
Land Cover Change ◽  
Land Surface ◽  
Temporal Change ◽  
Weather Prediction ◽  
Regional Climate ◽  
Land Use Land Cover ◽  
The Impact

<p>  Many socioeconomic changes have occurred in East Asia in recent decades. Due to the economic structural change and economic growth, a large population has been concentrated in the cities, resulting in rapid urban expansion. Besides, the surrounding agricultural land for food resources has also expanded, and deforestation has also been active at the same time. These land use/land cover change (LULCC) significantly alter the energy properties of the land surface. Although land surface characteristics that have vigorous variability over time, it is common in a numerical model to treat the information as a static condition. In a numerical weather prediction model aiming at short-term forecasting, the ground characteristics without temporal change are valid; however, in the numerical climate model integrated over several decades, consideration of such variability is essential.<br>   In this study, we examine the impact of LULCC using the GRIMs (Global/Regional Integrated Model system), which covered regional climate simulation. Temporal change LULC over East Asia, especially cropland and urban, is constructed based on Land Use Harmonization data. Through the comparison of sensitivity experiments considered the LULCC overtime or not, it is confirmed that land surface effect on regional climate change over East Asia. </p>

Impacts of Anomalous Midlatitude Cyclone Activity over East Asia during Summer on the Decadal Mode of East Asian Summer Monsoon and Its Possible Mechanism

2017 ◽  
Vol 30 (2) ◽  
pp. 739-753 ◽  
Author(s):  
Haishan Chen ◽  
Fangda Teng ◽  
Wanxin Zhang ◽  
Hong Liao
Keyword(s):  
East Asia ◽  
Summer Monsoon ◽  
Land Surface ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Cyclone Activity ◽  
Asian Summer ◽  
The Impact ◽  
Decadal Mode

By using an objective identification and tracking algorithm of the cyclone, the statistics of midlatitude cyclone activity in East Asia during summer for the period 1979–2013 were analyzed. The impact of the midlatitude summer cyclone anomalies in East Asia on the decadal mode of East Asian summer monsoon (EASM) was investigated and possible mechanisms were proposed. The possible reasons for the anomalous cyclone activity from the perspective of land surface thermal forcing were also explored. Results indicate that the midlatitude summer cyclone activity over East Asia exhibits decadal changes in the period of 1979–2013 and is significantly weakened after early 1990s. Further analysis indicates that there is a close relationship between the midlatitude summer cyclone activity over East Asia and the decadal variation of EASM; when the midlatitude summer cyclone activity over East Asia is strong (weak), EASM tends to be intensified (weakened), and the weak cyclone activity after 1993 generally coincides with the decadal weakening of EASM. Moreover, there is a close linkage between the weakening of cyclonic activity after the early 1990s and the nonuniform surface warming of the Eurasian continent. Significant warming to the west of Mongolia tends to weaken the north–south temperature gradient and the atmospheric baroclinicity to its south and eventually can lead to weakening of the midlatitude cyclone activity over East Asia.

scholarly journals A 10 km North American precipitation and land-surface reanalysis based on the GEM atmospheric model

2021 ◽  
Vol 25 (9) ◽  
pp. 4917-4945
Author(s):  
Nicolas Gasset ◽  
Vincent Fortin ◽  
Milena Dimitrijevic ◽  
Marco Carrera ◽  
Bernard Bilodeau ◽  
...  
Keyword(s):  
North American ◽  
Land Surface ◽  
Lower Troposphere ◽  
Summer Precipitation ◽  
Atmospheric Model ◽  
Dew Point ◽  
Land Data Assimilation ◽  
Precipitation Analysis ◽  
Land Data Assimilation System ◽  
The Impact

Abstract. Environment and Climate Change Canada has initiated the production of a 1980–2018, 10 km, North American precipitation and surface reanalysis. ERA-Interim is used to initialize the Global Deterministic Reforecast System (GDRS) at a 39 km resolution. Its output is then dynamically downscaled to 10 km by the Regional Deterministic Reforecast System (RDRS). Coupled with the RDRS, the Canadian Land Data Assimilation System (CaLDAS) and Precipitation Analysis (CaPA) are used to produce surface and precipitation analyses. All systems used are close to operational model versions and configurations. In this study, a 7-year sample of the reanalysis (2011–2017) is evaluated. Verification results show that the skill of the RDRS is stable over time and equivalent to that of the current operational system. The impact of the coupling between RDRS and CaLDAS is explored using an early version of the reanalysis system which was run at 15 km resolution for the period 2010–2014, with and without the use of CaLDAS. Significant improvements are observed with CaLDAS in the lower troposphere and surface layer, especially for the 850 hPa dew point and absolute temperatures in summer. Precipitation is further improved through an offline precipitation analysis which allows the assimilation of additional observations of 24 h precipitation totals. The final dataset should be of particular interest for hydrological applications focusing on transboundary and northern watersheds, where existing products often show discontinuities at the border and assimilate very few – if any – precipitation observations.

Impact of LULC Changes on LST in Rajshahi District of Bangladesh: A Remote Sensing Approach

2020 ◽  
Vol 3 (1) ◽  
pp. 11-23 ◽  
Author(s):  
Abdulla Al Kafy ◽  
Abdullah Al-Faisal ◽  
Mohammad Mahmudul Hasan ◽  
Md. Soumik Sikdar ◽  
Mohammad Hasib Hasan Khan ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Surface Temperature ◽  
Land Surface ◽  
Agricultural Land ◽  
Global Climate ◽  
Urban Expansion ◽  
Water Bodies ◽  
Landsat 8 ◽  
Lulc Changes ◽  
The Impact

Urbanization has been contributing more in global climate warming, with more than 50% of the population living in cities. Rapid population growth and change in land use / land cover (LULC) are closely linked. The transformation of LULC due to rapid urban expansion significantly affects the functions of biodiversity and ecosystems, as well as local and regional climates. Improper planning and uncontrolled management of LULC changes profoundly contribute to the rise of urban land surface temperature (LST). This study evaluates the impact of LULC changes on LST for 1997, 2007 and 2017 in the Rajshahi district (Bangladesh) using multi-temporal and multi-spectral Landsat 8 OLI and Landsat 5 TM satellite data sets. The analysis of LULC changes exposed a remarkable increase in the built-up areas and a significant decrease in the vegetation and agricultural land. The built-up area was increased almost double in last 20 years in the study area. The distribution of changes in LST shows that built-up areas recorded the highest temperature followed by bare land, vegetation and agricultural land and water bodies. The LULC-LST profiles also revealed the highest temperature in built-up areas and the lowest temperature in water bodies. In the last 20 years, LST was increased about 13ºC. The study demonstrates decrease in vegetation cover and increase in non-evaporating surfaces with significantly increases the surface temperature in the study area. Remote-sensing techniques were found one of the suitable techniques for rapid analysis of urban expansions and to identify the impact of urbanization on LST.

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