A synthetic report of recent climatic changes and their impacts on energy and water budgets over the Tibetan Plateau (TP) Kun Yang, Jun Qin, Wenjun Tang Institute of Tibetan Plateau Research (ITP) Chinese Academy of Sciences “Third Pole Environment” 3rd Workshop, Iceland, 30 Aug – 1 Sep, 2011

Outline Observed climatic changes Dependence of temperature and wind speed trends on elevation Solar radiation trend across China and TP Thermal response to climatic change Hydrological response to climatic change Potential collaboration in Glacier studies

Climatology of Precipitation in TP Wet in SE-TP, Dry in NW-TP

Climate change during Tibetan Plateau has been experiencing a rapid warming and wetting while wind speed and sunshine duration are declining in recent decades. (Yang et al., 2011 climatic change)

Altitudinal dependence of recent rapid warming over the Tibetan Plateau 1. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, China 2. Department of Geography, University of Maryland, USA Jun Qin 1, Kun Yang 1, Shunlin Liang 2, Xiaofeng Guo 1 (Qin et al., 2009 Climatic Change)

Validate MODIS observed LST trend Station warming rate MODIS warming rate (Qin et al., 2009 Climatic Change)

Warming rate derived from MODIS data ? 4800m increases with the altitude below 4800 m, keeps stable above 4800 m, declines above 6200 m (Qin et al., 2009 Climatic Change)

Wind speed trend in China and TP Surface wind speed variability increases with elevation 1960 ‐ ‐ ‐ 2009

Upper-air wind speed changed similarly! 500 hPa800 hPa 1960 ‐ ‐ ‐ hPa800 hPa

Differential geopotential heights (North, Middle, South) on 500hPa (from radiosonde) PGF change well corresponds to wind speed change

A number of studies indicate there was a dimming (solar radiation decreasing) in the world since 1960s, but a transition from dimming to brightening at the beginning of 1990s. (Wild et al., 2005 Science) Similar results were reported for China Solar radiation trend across China (Tang et al., 2011 ACP)

Trends at all CMA stations from 1961 to 1989 Diming from 1990 to 2006 No brightening trend (Tang et al., 2011 ACP)

Regional mean trend AuthorsNumber of Stations Trend slopes (W m -2 year -1 ) Che et al. (2005) Liang et al. (2005) Shi et al. (2008) Present -Model Present –ANN Present- Model Linear fitting dynamic harmonic regression (Tang et al., 2011 ACP) The magnitude of solar radiation trend was over-estimated

Is the difference due to station representativeness? Time series of sunshine duration (hour/year) during 1961 ~ (Tang et al., 2011 ACP) all CMA routine stations all radiation stations

How to explain the trend? Due to pollutants? TP is less polluted area, but the decreasing magnitude over TP is even larger than the average over China (-0.2 Wm -2 /a) (Tang et al., 2011 ACP)

Thermal Response to Climate Change over the Tibetan Plateau Method: combine Surface obs., Satellite and LSM (Yang et al., 2011 J. Clim)

Westerly Monsoon Heat source

Thermal anomaly  Monsoon variability

Latent heat release Sensible heat Rn_toa Rn_sfc Air Surface Atmospheric heating Heat source =H + lP +  R where  R=Rn_toa – Rn_sfc

Spatial distribution of the total heat source (Yang et al., 2011 J. Clim) This spatial pattern is contrast to the one presented in most of previous studies

Heat source trends H Rc TH H: decrease, the magnitude is ~ 1/2-1/3 of conventional estimate RC: decrease, the magnitude is ~ 1/2 of conventional estimate TH: decrease, the magnitude is ~ 1/2 of conventional estimate (Yang et al., 2011 J. Clim)

Heat source trend over China

Modeled hydrological cycle response to climate change Runoff anomaly ~ Discharge anomaly

Hydrological cycle response to climate change P E RoffSM (Yang et al., 2011 climatic change)

Physical picture of climate change over TP Global warming More warming in North than in South Weaken upper-air PGF Reduce wind speed Weaken Bowen-ratio Less heat transfer from Plateau Enhance local warming Enhance OLR Heat source decrease More evaporation Less discharge from Plateau Less sensible heat Enhance radiative cooling Weaken monsoon

Parlang No.4 Glacier 11.7km2 in area 8 km long Glacier experiments in TP

 May 20 to September 9, 2009  Southeast Tibetan Plateau  Palong-Zangbu No. 4 glacier  ablation zone  (29  15N, 96  55E) / 4800 m ASL  eddy-covariance (EC) system (CSAT3; LI-7500) / 10 Hz  CNR1 radiometers  HMP45C temp. & R.H. sensor  mass balance stakes (N=9) (05-20) (06-21) (08-02) The first turbulence station on a Tibetan glacier

LE (W m -2 ) H (W m-2) Diurnal variations of the turbulent fluxes (Guo et al., 2011 BLM) Turbulent heat fluxes are not so strong

Parameterizing sensible heat flux (Guo et al., 2011 BLM)

Parameterizing latent heat flux (Guo et al., 2011 BLM)

Ablation and energy budget (Yang W et al., 2011 JGR) Accumulated melt Components contributing to melt Ablation is rapid, and net radiation is the major contributor

A global survey: Rnet/Emelt The ratios for Tibetan glaciers are higher than for other regions Tibet Others

Welcome cooperative work in  Climatic change  Glacier melting modeling  Glacier change Thank you for your attention!