Characteristic Parameters Of Near Surface Layer Of The Traverse Route From Zhongshan Station To Dome-A, East Antarcitca

Data from Zhongshan station (eddy covariance measurements, gradient measurements andconventional ground-based meteorological observations) and three automatic weather stationsunder the cooperation between Chinese and Australian deployed along the traverse route fromZhongshan station (ZS) to Dome-A, East Antarctica, are used to analyze the impacts of snowaccumulation on the AWS observations under the Antarctic ice sheet, and corrected the AWSobserved data; discussed the surface climatology along the traverse route from Zhongshan toDome-A; compared seven common schemes of the turbulent fluxes parameterization anddiscussed their applicability over the underlaying surface of the Antarctic ice sheet; andstudied the seasonal variation of surface turbulent parameters. The results showed that:1. The analyses of the impacts of snow accumulation on the AWS observations show that:the impact on air/firn temperature from accumulation is decreasing with the height/depth fromthe surface and the impact is very small on 10m-depth snow temperature. The annual meantemperature differences (TD) between corrected and observed are about 1℃for 1m-level airtemperature and 0.1m-depth snow temperature. Air temperature TD is increasing withelevation from the coastal zone to the interior plateau because it is closely related to the localtemperature inversion. The averaged air temperature TD is almost positive except in summerwithout inversion at times. The magnitude of it is mainly determined by accumulation and theintensity of local surface inversion. Averaged firn temperature TD is negative in summer andpositive in winter.2. The climatological results of the traverse route from ZS to Dome-A show that: air/snowtemperature, accumulation and specific humidity decrease with increasing elevation anddistance from the coast. Annual mean air temperature and specific humidity decreases from-9.2℃and 1.154 g/kg at ZS to-51.2℃and 0.044 g/kg at Dome A. Accumulation declinesfrom 0.199 at LGB69 to 0.032 m w.e./a at Dome A. The mean surface wind speeds and winddirection consistency increase rapidly from the coast to the escarpment region, followed byrapid reductions towards the interior plateau with the strongest winds occurring at sites withthe greatest surface slopes. It depicts that the katabatic wind is strongest at LGB69 and it is notcoming into being at Dome A. Temperature and pressure all shows a distinct semiannualoscillation with a main minimum in spring and a secondary minimum in autumn. The strength and amplitude of temperature SAO signal increase rapidly from the coast to the interiorplateau. The pressure SAO signal performs weak at the strongest katabatic wind zone andstrong at the coast and the interior plateau, with the obvious three-wave structure for its annualoscillation.3. The studies of the turbulent fluxes parameterization show that: Both Businger (1971)scheme and Dyer-Hicks (1970) scheme are not suitable for calculating the turbulent fluxesunder the underlaying surface of the Antarctic ice sheet. By comparing the seven commonturbulent fluxes parameterization schemes, we find that COARE and Holtslag-Beljaars (1991)schemes are the best when simulated sensible heat flux under the convection conditions andPleim (2006) scheme is an optimal scheme for the stable stratification. Louis (1982) and Uno(1995) schemes, which employ bulk Richardson number Ri_B as stability factor, perform betterfor simulating the turbulent fluxes over Antarctic ice sheet than those of usingζas stabilityfactor, such as Businger (1971), Dyer-Hicks (1970), COARE and Holtslag-Beljaars (1991).The effects of Pleim (2006), using Ri_B to calculateζfor stability factor, fall in between this twomethods. In conclusion, Louis (1982) scheme is optimum for simulating the turbulent fluxeson the Antarctic ice sheet.4. The analyses of temporal and spatial features of turbulent parameters along the traverseroute from Zhongshan to Dome-A show that: H and LE have obvious annual variation. Inwinter, the near-surface air transports the energy mainly in the form of sensible heat flux to thesnow/ice surface to make up for the surface radiative heat loss. It shows the typical feature ofthe Antarctic surface energy balance (SEB) in winter. LE is more significant for SEB only inthe coastal areas, and its value is considerable small with the daily mean during winter <1W/m~2 in interior plateau. In summer, the surface transfers the energy to atmosphere not onlyin the form of latent heat, H is also very important, especially in the noon when theatmospheric stratification is in unstable condition. It is particularly in the inland plateau, thedaily mean of H can reach up to 10 W/m~2 in summer. Under the neutral stratificationconditions, the surface roughness length, dray coefficient and friction velocity are largest inthe strong katabatic zone and then rapid decrease to the coast and inland plateau, with theminimum value at Dome-A. This feature is consistent with the characteristic of wind variationand directly related to wind speed.