Modeling the Effects of Lakes in the Tibetan Plateau on Diurnal Variations of Regional Climate and Their Seasonality

2020 ◽  
Vol 21 (11) ◽  
pp. 2523-2536
Author(s):  
Lingjing Zhu ◽  
Jiming Jin ◽  
Yimin Liu
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate ◽  
Wrf Model ◽  
Surface Air Temperature ◽  
Diurnal Variations ◽  
The Tibetan Plateau ◽  
Near Surface ◽  
Local Climate ◽  
Lake Model ◽  
Physically Based

AbstractIn this study, we investigated the effects of lakes in the Tibetan Plateau (TP) on diurnal variations of local climate and their seasonal changes by using the Weather Research and Forecasting (WRF) Model coupled with a one-dimensional physically based lake model. We conducted WRF simulations for the TP over 2000–10, and the model showed excellent performance in simulating near-surface air temperature, precipitation, lake surface temperature, and lake-region precipitation when compared to observations. We carried out additional WRF simulations where all the TP lakes were replaced with the nearest land-use types. The differences between these two sets of simulations were analyzed to quantify the effects of the TP lakes on the local climate. Our results indicate that the strongest lake-induced cooling occurred during the spring daytime, while the most significant warming occurred during the fall nighttime. The cooling and warming effects of the lakes further inhibited precipitation during summer afternoons and evenings and motivated it during fall early mornings, respectively. This study lays a solid foundation for further exploration of the role of TP lakes in climate systems at different time scales.

scholarly journals Convection-Permitting Regional Climate Simulations Over Tibetan Plateau: Re-Initialization Versus Spectral Nudging

2021 ◽  
Author(s):  
Mengnan Ma ◽  
Pinhong Hui ◽  
Dongqing Liu ◽  
Peifeng Zhou ◽  
Jianping Tang
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate ◽  
Wrf Model ◽  
Surface Air Temperature ◽  
Moisture Flux ◽  
Early Morning ◽  
Climate Simulation ◽  
Cold Bias ◽  
The Tibetan Plateau ◽  
Spectral Nudging

Abstract Two regional climate simulation experiments (spectral nudging and re-initialization) at convection-permitting scale are conducted using the WRF model over the Tibetan Plateau (TP). The surface air temperature (T2m) and the precipitation in summer during 2016–2018 are evaluated against the in-situ station observations and the Global Satellite Mapping of Precipitation (GSMaP) dataset. The results show that both experiments can successfully capture the spatial distribution and the daily variation of T2m and precipitation, with reasonable cold bias for temperature, dry bias for precipitation when compared with the station observations. In addition, the diurnal cycle of precipitation is investigated, indicating that both experiments tend to simulate the afternoon precipitation in advance and postpone the night precipitation. The precipitation bias is reduced by using the spectral nudging technique, especially at night and early morning. Possible causes for the differences between the two experiments are also analyzed. The daytime surface net radiation contributes a lot to the cold biases in the re-initialization experiment, and the stronger low-level moisture flux convergence leads to the wet biases. These results can provide valuable guidance for further fine-scale simulation studies over the TP.

Recent Trends in Land Surface Temperature on the Tibetan Plateau

2006 ◽  
Vol 19 (12) ◽  
pp. 2995-3003 ◽  
Author(s):  
Yuichiro Oku ◽  
Hirohiko Ishikawa ◽  
Shigenori Haginoya ◽  
Yaoming Ma
Keyword(s):  
Tibetan Plateau ◽  
Surface Temperature ◽  
Air Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Precipitation Amount ◽  
Surface Air Temperature ◽  
The Tibetan Plateau ◽  
Near Surface ◽  
Diurnal Range

Abstract The diurnal, seasonal, and interannual variations in land surface temperature (LST) on the Tibetan Plateau from 1996 to 2002 are analyzed using the hourly LST dataset obtained by Japanese Geostationary Meteorological Satellite 5 (GMS-5) observations. Comparing LST retrieved from GMS-5 with independent precipitation amount data demonstrates the consistent and complementary relationship between them. The results indicate an increase in the LST over this period. The daily minimum has risen faster than the daily maximum, resulting in a narrowing of the diurnal range of LST. This is in agreement with the observed trends in both global and plateau near-surface air temperature. Since the near-surface air temperature is mainly controlled by LST, this result ensures a warming trend in near-surface air temperature.

scholarly journals Holocene vegetation and biomass changes on the Tibetan Plateau – a model-pollen data comparison

2011 ◽  
Vol 7 (2) ◽  
pp. 1073-1111
Author(s):  
A. Dallmeyer ◽  
M. Claussen ◽  
U. Herzschuh ◽  
N. Fischer
Keyword(s):  
Tibetan Plateau ◽  
Land Cover ◽  
Land Cover Change ◽  
Vegetation Change ◽  
Climatic Factors ◽  
Surface Air Temperature ◽  
Total Biomass ◽  
The Tibetan Plateau ◽  
Near Surface ◽  
Vegetation Shift

Abstract. Results of a transient numerical experiment, performed in a coupled atmosphere-ocean-vegetation model with orbital forcing alone, are compared to pollen-based vegetation reconstructions from four representative sites on the Tibetan Plateau, covering the last 6000 years. Causes of the vegetation change and consequences for the biomass storage are analysed. In general, simulated and reconstructed vegetation trends at each site are in good agreement. Both methods reveal a general retreat of the biomass-rich vegetation that is particularly manifested in a strong decrease of forests. However, model and reconstructions differ with regard to the climatic factors causing this vegetation change. The reconstructions primarily identify decreasing summer monsoon precipitation as the responsible mechanism for the vegetation shift. In the model, the land cover change originates from differences in near-surface air temperature arising out of orbitally-induced insolation changes. According to the model results, the averaged forest fraction on the Plateau is shrinking by almost one-third from mid-Holocene (41.4%) to present-day (28.3%). Shrubs, whose fraction is quadrupled at present-day (12.3%), replace most of this forest. Gras fraction increases from 38.9% during the mid-Holocene to 42.3% at present-day. This land cover change results in a decrease of living biomass by 0.62 kgC m−2. Total biomass on the Tibetan Plateau decreases by 1.9 kgC m−2, i.e. approx. 6.64 PgC are released due to the natural land cover change.

scholarly journals Analysis On The Regional Features of Future Warming Using High-Resolution Downscaled Multi-Model Climate Scenarios In China

2021 ◽  
Author(s):  
Lei Zhang ◽  
Yinlong Xu ◽  
Chunchun Meng ◽  
Yuncheng Zhao ◽  
Changgui Wang
Keyword(s):  
Heat Stress ◽  
High Resolution ◽  
Tibetan Plateau ◽  
Air Temperature ◽  
South China ◽  
Surface Air Temperature ◽  
Northern China ◽  
The Tibetan Plateau ◽  
Near Surface ◽  
Future Warming

Abstract The frequency and magnitude of global warming events varies greatly across different regions and countries. The climatic diversity for China and future warming features are projected across twelve climatic zones based on the ensemble of the five well-performing high resolution downscaled climate models for each zone. There are warming patterns for the mean near surface air temperature (Tm), maximum near surface air temperature (Tmax), minimum near surface air temperature (Tmin) as well as heat stress and frost events. Under RCP4.5 and RCP8.5 scenarios, the three indices (i.e., Tm, Tmax and Tmin) countrywide are likely to increase at respective rates of 0.30-0.31 and 0.64-0.67 oC per decade. The extent of freezing-event extent (FE) are projected to decrease at a rate of -1912 and -4442 day·km2 per decade while the extent of heat-stress event (HE) increase at 1116 and 3557 day·km2 per decade. A higher increment in temperatures as well as a decreasing trend in the diurnal temperature range (DTR) and frost days and FE are present on the Tibetan Plateau and northern China including Xinjiang, Northeast China, the eastern part of northwest China, Inner Mongolia and North China. These trends are opposite to those projected for southern China including Huanghuai, Jianghuai, Jianghan, the south Yangzi River, South China and Southwestern China. The warming occur faster in the current colder zones (northern China and the Tibetan Plateau) while heat stress is more intense and severe in Jianghuai, Jianghan, the south Yangzi River, South China and Xinjiang. These potential changes indicate that adaption and mitigation strategies are necessary in response to future warming.

scholarly journals On the freeze–thaw cycles of shallow soil and connections with environmental factors over the Tibetan Plateau

2021 ◽  
Author(s):  
Ning Li ◽  
Lan Cuo ◽  
Yongxin Zhang
Keyword(s):  
Tibetan Plateau ◽  
Soil Temperature ◽  
Coniferous Forest ◽  
Soil Layer ◽  
Surface Air Temperature ◽  
The Tibetan Plateau ◽  
Near Surface ◽  
Freeze Thaw ◽  
Shallow Soil ◽  
Thaw Cycle

Abstract Changes in the freeze–thaw cycles of shallow soil have important consequences for surface and subsurface hydrology, land–atmosphere energy and moisture interaction, carbon exchange, and ecosystem diversity and productivity. This work examines the shallow soil freeze–thaw cycle on the Tibetan Plateau (TP) using in–situ soil temperature observations in 0–20 cm soil layer during July 1982 – June 2017. The domain and layer averaged beginning frozen day is November 18 and delays by 2.2 days per decade; the ending frozen day is March 9 and advances by 3.2 days per decade; the number of frozen days is 109 and shortens by 5.2 days per decade. Altitude and latitude combined could explain the spatial patterns of annual mean freeze–thaw status well. Stations located near 0–ºC contour line experienced dramatic changes in freeze–thaw cycles as seen from subtropical mountain coniferous forest in the southern TP. Soil completely freezes from surface to 20–cm depth in 15 days while completely thaws in 10 days on average. Near–surface soil displays more pronounced changes than deeper soil. Surface air temperature strongly influences the shallow soil freeze – thaw status but snow exerts limited effects. Different thresholds in freeze–thaw status definition lead to differences in the shallow soil freeze–thaw status and multiple–consecutive–day approach appears to be more robust and reliable. Gridded soil temperature products could resolve the spatial pattern of the observed shallow soil freeze–thaw status to some extent but further improvement is needed.

scholarly journals Measurement Report: Determination of aerosol vertical features on different time-scales over East Asia based on CATS aerosol products

2020 ◽  
Author(s):  
Yueming Cheng ◽  
Tie Dai ◽  
Jiming Li ◽  
Guangyu Shi
Keyword(s):  
Seasonal Variation ◽  
Tibetan Plateau ◽  
East Asia ◽  
North China ◽  
Surface Wind ◽  
Diurnal Variations ◽  
Dust Particles ◽  
The Tibetan Plateau ◽  
Anthropogenic Aerosols ◽  
Near Surface

Abstract. The Cloud-Aerosol Transport System (CATS) lidar, on board the International Space Station (ISS), provides a new opportunity for studying aerosol vertical distributions, especially the diurnal variations from space observations. In this study, we investigate the seasonal variations and diurnal cycles of the vertical aerosol extinction coefficients (AECs) over East Asia by taking advantage of 32 months of the continuous and uniform aerosol measurements from the CATS lidar. Over the Tibetan Plateau, a belt of AECs approximately 6 km between 30° N and 38° N persistently exists in all seasons with an obviously seasonal variation. In summer, the aerosols at 6 km are identified as a mixture of both anthropogenic aerosols transported from India and coarse dust particles from Asian dust sources. In addition, the high AECs up to 8 km in summer over the Tibetan Plateau are caused by smoke aerosols from thermal dynamic processes. In fall and winter, the north slope of the plateau is continuously influenced by both dust aerosols and polluted aerosols transported upslope from the cities located in northwestern Asia at lower elevations. The diurnal variation of AECs in North China is mainly related to the diurnal variations of the transported dust and local polluted aerosols. Below 2 km, the AEC profiles in North China at 06:00 local Time (LT) and 12:00 LT are significantly higher than those at 00:00 LT and 18:00 LT, reaching the maximum at midday. The aerosol vertical profiles over the Tarim desert region in summer have obvious diurnal variations with the AECs at 12:00 LT and 18:00 LT being significantly higher than those at 00:00 LT and 06:00 LT, which are induced by the strongly diurnal variations in near-surface wind speeds. In addition, the peak of the AEC profiles has a significant seasonal variation, which is mainly determined by the boundary layer height.

scholarly journals Creating New Near-Surface Air Temperature Datasets to Understand Elevation-Dependent Warming in the Tibetan Plateau

2020 ◽  
Vol 12 (11) ◽  
pp. 1722
Author(s):  
Mingxi Zhang ◽  
Bin Wang ◽  
James Cleverly ◽  
De Li Liu ◽  
Puyu Feng ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Air Temperature ◽  
Land Surface ◽  
Vegetation Indices ◽  
Surface Air Temperature ◽  
The Tibetan Plateau ◽  
Global Studies ◽  
Near Surface ◽  
Automated Mapping ◽  
Land Surface Temperatures

The Tibetan Plateau has been undergoing accelerated warming over recent decades, and is considered an indicator for broader global warming phenomena. However, our understanding of warming rates with elevation in complex mountain regions is incomplete. The most serious concern is the lack of high-quality near-surface air temperature (Tair) datasets in these areas. To address this knowledge gap, we developed an automated mapping framework for the estimation of seamless daily minimum and maximum Land Surface Temperatures (LSTs) for the Tibetan Plateau from the existing MODIS LST products for a long period of time (i.e., 2002–present). Specific machine learning methods were developed and linked with target-oriented validation and then applied to convert LST to Tair. Spatial variables in retrieving Tair, such as solar radiation and vegetation indices, were used in estimation of Tair, whereas MODIS LST products were mainly focused on temporal variation in surface air temperature. We validated our process using independent Tair products, revealing more reliable estimates on Tair; the R2 and RMSE at monthly scales generally fell in the range of 0.9–0.95 and 1–2 °C. Using these continuous and consistent Tair datasets, we found temperature increases in the elevation range between 2000–3000 m and 4000–5000 m, whereas the elevation interval at 6000–7000 m exhibits a cooling trend. The developed datasets, findings and methodology contribute to global studies on accelerated warming.

scholarly journals Double-Nested Dynamical Downscaling Experiments over the Tibetan Plateau and Their Projection of Climate Change under Two RCP Scenarios

2013 ◽  
Vol 70 (4) ◽  
pp. 1278-1290 ◽  
Author(s):  
Zhenming Ji ◽  
Shichang Kang
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Climate Model ◽  
Dynamical Downscaling ◽  
Regional Climate ◽  
Surface Air Temperature ◽  
Horizontal Resolution ◽  
The Tibetan Plateau ◽  
Rcp Scenarios ◽  
Temperature And Precipitation

Abstract A high-resolution regional climate model is used to simulate climate change over the Tibetan Plateau (TP). The model is driven at the grid spacing of 10 km by nesting the outputs of 50-km-resolution simulations. The results show that the models can capture the spatial and temporal distributions of the surface air temperature over the TP. The so-called double-nested method has a higher horizontal resolution and represents more spatial details. For example, the temperature simulations from the double-nested method reflect the observations better compared to the 50-km-resolution models. This is mainly due to the fact that topographical effects of complex terrains are detected better at higher resolution. Although both models can represent the basic patterns of precipitation, the simulated results are not as good as those of temperature. In the future, significant warming seems to develop over the TP under two representative concentration pathway (RCP) scenarios. Greater increases occur in December–February (DJF) compared with June–August (JJA). The increasing temperature trend is more pronounced over the Gangdese Mountains and over the Himalayas than in the central TP. The projection of precipitation shows the main increases in DJF. In JJA, it predicts decreases or slight changes in the southern TP. The comparison between RCP8.5 and RCP4.5 scenarios shows a similar spatial distributions of temperature and precipitation, whereas the respective values of RCP8.5 are enhanced compared with those under RCP4.5.

Sign in / Sign up

Export Citation Format

Share Document