Diurnal variations of circulation and precipitation in the vicinity of the Tibetan Plateau in early summer

2008 ◽  
Vol 32 (1) ◽  
pp. 55-73 ◽  
Author(s):  
K. C. Chow ◽  
Johnny C. L. Chan
Keyword(s):  
Tibetan Plateau ◽  
Early Summer ◽  
Diurnal Variations ◽  
The Tibetan Plateau

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.

Diurnal Variations of Warm-Season Precipitation East of the Tibetan Plateau over China

2011 ◽  
Vol 139 (9) ◽  
pp. 2790-2810 ◽  
Author(s):  
Xinghua Bao ◽  
Fuqing Zhang ◽  
Jianhua Sun
Keyword(s):  
Tibetan Plateau ◽  
Warm Season ◽  
Propagation Speed ◽  
Western Pacific Subtropical High ◽  
Diurnal Variations ◽  
The Tibetan Plateau ◽  
Diurnal Cycles ◽  
Thermally Driven ◽  
The Difference ◽  
Precipitation Cycle

This study explores the diurnal variations of the warm-season precipitation to the east of the Tibetan Plateau over China using the high-resolution NOAA/Climate Prediction Center morphing technique (CMORPH) precipitation data and the Global Forecast System (GFS) gridded analyses during mid-May to mid-August of 2003–09. Complementary to the past studies using satellite or surface observations, it is found that there are strong diurnal variations in the summertime precipitation over the focus domain to the east of the Tibetan Plateau. These diurnal precipitation cycles are strongly associated with several thermally driven regional mountain–plains solenoids due to the differential heating between the Tibetan Plateau, the highlands, the plains, and the ocean. The diurnal cycles differ substantially from region to region and during the three different month-long periods: the pre-mei-yu period (15 May–15 June), the mei-yu period (15 June–15 July), and the post-mei-yu period (15 July–15 August). In particular, there is a substantial difference in the propagation speed and eastward extent of the peak phase of the dominant diurnal precipitation cycle that is originated from the Tibetan Plateau. This diurnal peak has a faster (slower) eastward propagation speed, the more (less) coherent propagation duration, and thus covers the longest (shortest) distance to the east during the pre-mei-yu (post-mei-yu) period than that during the mei-yu period. The differences in the mean midlatitude westerly flow and in the positioning and strength of the western Pacific subtropical high during different periods are the key factors in explaining the difference in the propagation speed and the eastward extent of this dominant diurnal precipitation cycle.

scholarly journals Moisture and Temperature Covariability over the Southeastern Tibetan Plateau during the Past Nine Centuries

2020 ◽  
Vol 33 (15) ◽  
pp. 6583-6598
Author(s):  
Jianglin Wang ◽  
Bao Yang ◽  
Fredrik Charpentier Ljungqvist
Keyword(s):  
Tibetan Plateau ◽  
Climate Model ◽  
Severity Index ◽  
Early Summer ◽  
Convective Precipitation ◽  
Drought Severity ◽  
The Tibetan Plateau ◽  
Low Frequencies ◽  
The Past ◽  
Spatial Coverage

AbstractAccurate projections of moisture variability across the Tibetan Plateau (TP) are crucial for managing regional water resources, ecosystems, and agriculture in densely populated downstream regions. Our understanding of how moisture conditions respond to increasing temperatures over the TP is still limited, due to the short length of instrumental data and the limited spatial coverage of high-resolution paleoclimate proxy records in this region. This study presents a new, early-summer (May–June) self-calibrating Palmer drought severity index (scPDSI) reconstruction for the southeastern TP (SETP) covering 1135–2010 CE using 14 tree-ring records based on 1669 individual width sample series. The new reconstruction reveals that the SETP experienced the longest period of pluvial conditions in 1154–75 CE, and the longest droughts during the periods 1262–80 and 1958–76 CE. The scPDSI reconstruction shows stable and significant in-phase relationships with temperature at both high and low frequencies throughout the past 900 years. This supports the hypothesis that climatic warming may increase moisture by enhancing moisture recycling and convective precipitation over the SETP; it is also consistent with climate model projections of wetter conditions by the late twenty-first century in response to global warming.

scholarly journals Regionalization of seasonal precipitation over the Tibetan Plateau and associated large-scale atmospheric systems

2020 ◽  
pp. 1-45
Author(s):  
Hui-Wen Lai ◽  
Hans W. Chen ◽  
Julia Kukulies ◽  
Tinghai Ou ◽  
Deliang Chen
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Large Scale ◽  
Late Summer ◽  
Early Summer ◽  
The Tibetan Plateau ◽  
Summer Peak ◽  
Precipitation Seasonality ◽  
Winter Peak

AbstractPrecipitation over the Tibetan Plateau (TP) has major societal impacts in South and East Asia, but its spatiotemporal variations are not well understood mainly because of the sparsely distributed in-situ observation sites. With help of the Global Precipitation Measurement satellite product IMERG and ERA5 reanalysis, distinct precipitation seasonality features over the TP were objectively classified using a self-organizing map algorithm fed with ten-day averaged precipitation from 2000 to 2019. The classification reveals three main precipitation regimes with distinct seasonality of precipitation: winter peak, centered at the western plateau; early summer peak, found on the eastern plateau; and late summer peak, mainly located on the southwestern plateau. On a year-to-year basis, the winter peak regime is relatively robust, while the early summer and late summer peak regimes tend to shift mainly between the central and northern TP, but are robust in the eastern and southwestern TP. A composite analysis shows that the winter peak regime experiences larger amounts of precipitation in winter and early spring when the westerly jet is anomalously strong to the north of the TP. Precipitation variations in the late summer peak regime are associated with intensity changes in the South Asian High and Indian summer monsoon. The precipitation in the early summer peak regime is correlated with the Indian summer monsoon together with anticyclonic circulation over the western North Pacific. The results provide a basic understanding of precipitation seasonality variations over the TP and associated large-scale conditions.

scholarly journals Future Climate in the Tibetan Plateau from a Statistical Regional Climate Model

2013 ◽  
Vol 26 (24) ◽  
pp. 10125-10138 ◽  
Author(s):  
Xiuhua Zhu ◽  
Weiqiang Wang ◽  
Klaus Fraedrich
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Early Summer ◽  
Maximum Temperature ◽  
Boreal Summer ◽  
The Tibetan Plateau ◽  
Temperature Trends ◽  
Precipitation Increase

Abstract The authors use a statistical regional climate model [Statistical Regional Model (STAR)] to project the Tibetan Plateau (TP) climate for the period 2015–50. Reanalysis datasets covering 1958–2001 are used as a substitute of observations and resampled by STAR to optimally fit prescribed linear temperature trends derived from the Max Planck Institute Earth System Model (MPI-ESM) simulations for phase 5 of the Coupled Model Intercomparison Project (CMIP5) under the representative concentration pathway 2.6 (RCP2.6) and RCP4.5 scenarios. To assess the related uncertainty, temperature trends from carefully selected best/worst ensemble members are considered. In addition, an extra projection is forced by observed temperature trends in 1958–2001. The following results are obtained: (i) Spatial average temperature will increase by 0.6°–0.9°C; the increase exceeds 1°C in all months except in boreal summer, thus indicating a reduced annual cycle; and daily minimum temperature rises faster than daily maximum temperature, resulting in a narrowing of the diurnal range of near-surface temperature. (ii) Precipitation increase mainly occurs in early summer and autumn possibly because of an earlier onset and later withdrawal of the Asian summer monsoon. (iii) Both frost and ice days decrease by 1–2 days in spring, early summer, and autumn, and the decrease of frost days on the annual course is inversely related to the precipitation increase. (iv) Degree-days increase all over the TP with peak amplitude in the Qaidam Basin and the southern TP periphery, which will result in distinct melting of the local seasonal frozen ground, and the annual temperature range will decrease with stronger amplitude in south TP.

Improved Simulation of the East Asian Summer Monsoon Rainfall with Satellite-Derived Snow Water Equivalent Data*

2009 ◽  
Vol 137 (6) ◽  
pp. 1790-1804 ◽  
Author(s):  
Kazuyoshi Souma ◽  
Yuqing Wang
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Snow Water Equivalent ◽  
Asian Summer Monsoon ◽  
Lower Troposphere ◽  
Seasonal Prediction ◽  
Summer Monsoon Rainfall ◽  
Early Summer ◽  
Shortwave Radiation ◽  
The Tibetan Plateau

Abstract The effect of Eurasian spring snow amount on the summer monsoon rainfall over East Asia has been studied both observationally and numerically. The results indicate that the Eurasian spring snow amount could be important for seasonal prediction of East Asian summer monsoon (EASM) rainfall. Therefore, accurately initializing snow could be critical to improving seasonal prediction of EASM rainfall by numerical models. An attempt has been made in this study to initialize snow in a regional climate model using snow water equivalent (SWE) data derived from a microwave imager. Results from an ensemble seasonal prediction experiment for the 2005 EASM show that the satellite-derived SWE data can be effectively used to initialize a dynamical seasonal prediction model, which leads to improved seasonal prediction of EASM rainfall. Possible effects of snow anomalies over the Tibetan Plateau on EASM rainfall were also studied through a comparative ensemble simulation in which snow was initialized by spinning up the same model from the previous winter. It is found that the anomalous snow amount over the Tibetan Plateau could lead to cooling of the surface and lower troposphere not only over the Tibetan Plateau but also in the surrounding areas because of the reduced net surface shortwave radiation associated with the high snow albedo. This would result in positive anomalies in geopotential height and weaken the cyclonic monsoon circulation in the lower troposphere in East Asia, causing a rainfall increase in South China but a reduction in the Yangtze River Valley in early summer (May–June). The difference in rainfall in midsummer (July–August) was not significant when compared with that in early summer. The surface heat budget indicates that the reduced net surface shortwave radiation is largely balanced by the reduced surface sensible heat flux.

The remote effect of the Tibetan Plateau on downstream flow in early summer

2011 ◽  
Vol 116 (D19) ◽  
Author(s):  
Yafei Wang ◽  
Xiangde Xu ◽  
Anthony R. Lupo ◽  
Pingyun Li ◽  
Zhicong Yin
Keyword(s):  
Tibetan Plateau ◽  
Early Summer ◽  
The Tibetan Plateau ◽  
Downstream Flow

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.

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