Knowledge Resource Center for Ecological Environment in Arid Area
| 祁连山老虎沟12号冰川能量-物质平衡模拟研究 | |
| 其他题名 | Modelling of surface energy-mass balance on the Laohugou Glacier No.12 in the Qilian Mountains, China |
| 孙维君 | |
| 出版年 | 2012 |
| 学位类型 | 博士 |
| 导师 | 任贾文 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 冰川表面能量平衡模型揭示了冰川消融的物理过程，建立了冰川消融与气候变化之间的联系。为了探讨干旱区高海拔冰川对气候变化的响应，利用老虎沟高山站海拔4200m、12号冰川消融区4550m和积累区海拔5040m自动气象站观测资料，分析了老虎沟流域的气候变化特征；确定了积累区和消融区冰川表面反照率，动量、热量和水汽粗糙度，动量拖曳系数、热量输送系数和水汽输送系数等地表特征参数及其变化规律；运用整体空气动力学法和涡动相关法计算并对比分析了感热和潜热通量的差异；结合能量平衡模型，分析了能量各分量变化特征，并估算了积累区和消融区消融期冰川表面能量收支状况；最后利用冰川表面雪深资料和花杆实测资料验证了能量平衡模型模拟的物质平衡，揭示了影响冰川消融的主导因素；通过变换模型中的参数变量，开展了气候敏感性试验，探讨了冰川对气候变化的响应过程，获得以下研究结果：\n（1）老虎沟地区气温具有年较差大，日较差小的气候特征；12号冰川温跃值随着气温升高而增大，6～8月平均温跃值为1.59℃；12号冰川表面气温垂直递减率随着气温升高而减小，年平均值为0.62℃；降水主要集中在5～9月份，占全年降水量的约72%；在6～8月出现典型的山谷风环流，但冰川风要强于谷风，在其他月份，冰川风占主导；总辐射超太阳常数现象主要发生在4～9月份，出现的时间集中在13︰00前后；海拔4200m和4550m总辐射月总量平均值分别为504.8 MJ m-2和540.8 MJ m-2，太阳能资源十分丰富。\n（2）12号冰川积累区和消融区空气动力学粗糙度Zom月平均值分别介于0.6～ 2.4 mm和1.3～7.8 mm之间，热传输附加阻尼kB-1并不是常数，在消融期（6～9月）要大于其他月份的；大气层结稳定时，动量拖曳系数CD和热量输送系数CH月平均值都介于0.0008 ~ 0.0013之间，大气层结不稳定时，海拔5040 m和4550 m CD和CH介于0.0021~ 0.0022间，因此运用整体空气动力学法计算冰川表面湍流通量中应选择合适的CD和CH值；Yang02方案和Andreas87方案在积累区计算的感热H和潜热LE相关性非常好，相关系数分别为0.99和0.94，绝对值误差分别为1.8和1.4 W m-2；Yang02方案和涡动相关法在消融区计算的H和LE也有较好的相关性，相关系数分别为0.89和0.86，Yang02方案计算的H低估了2.6 W m-2，LE被低估了0.7 W m-2。\n（3）冰川积累区消融期（1 Jun.-3 Sep. 2011），净短波辐射是冰川表面主要热量来源（93.5 W m-2/92%），其次是感热通量（8.6 W m-2/8%）；在能量支出项中，冰雪消融耗热和净长波辐射非常接近，分别占45%和43%，潜热通量所占比重最小（-11.9 W m-2/12%）；消融区消融期（1 Jun. – 30 Sept. 2011），净短波辐射也是冰川表面主要热量来源（126 W m-2/95%），其次是感热通量（6.5 W m-2/5%）；在能量支出项中，冰雪消融耗热占主导（52%），基本是净长波辐射（37%）和潜热通量（11%）之和；随着海拔的升高，在冰川表面能量收入项中，净辐射所占比重下降，在能量支出项中，冰雪消融耗热所占比重下降。\n（4）能量平衡模型能很好的模拟冰川物质平衡变化，积累区消融期物质平衡模拟值为-381 mm w.e.，比实测值偏大31 mm w.e.；消融区消融期（Jun.1- Sep.30,2011）物质平衡模拟值为-1703 mm w.e.，比实测值偏大90 mm w.e.。积累区和消融区在观测期间日蒸发/升华速率分别为0.3和0.4 mm w.e.。\n（5）在积累区和消融区，正积温和冰川表面反照率控制着冰川消融变化，沉降到冰川表面的粉尘降低了反照率，增强了冰川消融；消融区消融期(1 Jun.- 30 Sep.2011)粉尘使净短波辐射日平均值强迫增加了5.5～13.3 W m-2，消融量强迫增加了152.7～492.1 mm w.e.，与实际值相比增大了约8.6%～34.2%。\n（6）气候变化敏感性试验表明，与相对湿度、风速和降水变化相比较，物质平衡对气温变化最敏感；整体空气动力学法计算湍流通量过程中，稳定度修正是很必要的，否则会导致物质平衡高估约16.9%；空气动力学粗糙度的增加会使感热和潜热同时增大，由于两者可相互抵消，引起物质平衡的变化非常小；在辐射各分量变化中，物质平衡对净短波变化最敏感；物质平衡对反照率 变化非常敏感，当积累区 降低0.1时物质平衡增大90%，当消融区 变化0.1时，物质平衡变化36%。 |
| 英文摘要 | The energy balance of glacial surface can describe physical melting processes. The relationship between glacier ablation and climate change is established using surface energy balance model. In order to investigate the response of high-altitude glaciers in arid region to climate change, with the automatic weather station (AWS) meteorological data from the high-altitude station (4200 m a.s.l.), and ablation zone (4550 m a.s.l.) and accumulation zone (5040 m a.s.l.) of the Glacier No.12 in the Laohugou Valley, climate change characteristics of the Laohugou Valley were analyzed; albedo, roughness lengths for momentum, temperature and humidity, and transmission coefficients for momentum, temperature and humidity on the glacial surface of ablation and accumulation zones were obtained, which characteristics were analyzed. Contrastive analysis of sensible flux and latent flux were done respectively using the bulk aerodynamic approach and the eddy covariance method. Combined with surface energy balance model, the characteristics of components of energy balance were analyzed, and the glacial surface energy budget of the ablation and accumulation zones were estimated during the ablation period. The simulated mass balance was validated by the measured deduced from the sonic ranging sensors and the stakes data, and the main influenced factors on glacier ablation were revealed. Climate sensitivity test were carried out using changing parameter values and meteorological variables in the model, and discussed how the Glacier No.12 respond to climate change. The results were obtained as follow: \n(1) The Laohugou Valley was characterized by the climate with great annual range and little daily range of air temperature. Temperature jump of the Laohugou Glacier No.12 increased with air temperature rise and mean value from June to August was 1.59℃. Air temperature lapse rate decreased with air temperature rise, and annual mean value was 0.62℃. Precipitation occurred mainly from May to September, which accounted for 72% of annual precipitation. Mountain and valley breezes occurred from June to September, whereas glacier wind was stronger than valley wind, and glacier wind prevailed in other months. The phenomenon that down shortwave radiation was larger than solar constant mainly occurred around 13﹕00 from April to September. Solar energy resources are enormous with monthly mean values of global radiation amount 504.8 MJ m-2 and 540.8 MJ m-2 at the 4200 m a.s.l. and the 4550m a.s.l. respectively. \n(2) Monthly means of aerodynamic roughness length varied between 0.6 and 2.4 mm in the accumulation zone, and between 1.3 and 7.8 mm in the ablation zone. The resistance parameters for heat transfer kB-1 in the ablation period (from June to September) were not constant and larger than those in other months. When atmospheric condition is stable, monthly mean values of both momentum drag coefficient CD and heat transmission coefficient CH varied between 0.0008 and 0.0013. When atmospheric condition is unstable, both CD and CH varied between 0.0021 and 0.0022, therefore it is necessary to select appropriate CD and CH to calculate glacial surface heat fluxes with bulk aerodynamic method. The differences of sensible heat flux H and latent flux LE in the accumulation zone, calculated by Yang02 and Andreas87 approaches, were little with good correlation coefficients 0.99 and 0.94 respectively, and absolute value errors of 1.8 and 1.4 W m-2 respectively. The differences of sensible heat flux H and latent flux LE in the ablation zone, calculated by Yang02 and eddy covariance approaches, were little with good correlation coefficients 0.89 and 0.86 respectively. H and LE calculated by Yang02 method, were underestimated by 2.6 and 0.7 W m-2 respectively.\n(3) In the accumulation zone during ablation period (1 Jun.-3 Sep.2011), Net shortwave radiation was the primary source of the surface energy balance (93.5 W m-2/92%), followed by sensible heat flux (8.6 W m-2/8%). In the output of surface energy, melting energy was almost as large as net longwave radiation, accounting for 45% and 43% respectively, and latent heat flux was the least one (-11.9 W m-2/12%). In the ablation zone during ablation period (1 Jun. – 30 Sept. 2011), Net shortwave radiation was also the primary source of the surface energy balance (126 W m-2/95%), followed by sensible heat flux (6.5 W m-2/5%). Melting energy was the main output of surface energy (52%), and was almost as large as the sum of latent heat flux (37%) and subsurface heat flux (11%). As elevation rise, the proportion of net radiation decreased in the input of surface energy, and the proportion of melting energy also decreased. \n(4) Mass balance on the glacial surface can be simulated by surface energy balance model. Simulated mass balance was - 381 mm w.e. in the accumulation zone during ablation period, larger than the measured by 31 mm w.e. Simulated mass balance was -1703 mm w.e. in the ablation zone during ablation period, larger than the measured by 90 mm w.e. Daily rate of evaporation/ sublimation were 0.3 and 0.4 mm w.e. respectively in the accumulation and ablation zones.\n(5) In the accumulation and ablation zones, daily accumulated positive temperature and albedo govern the glacial surface ablation. Albedo decreased by the dust on the glacial surface, and glacial surface ablation increased. In the ablation zone during ablation period (1 Jun.- 30 Sep.2011), the glacial surface dust forced daily mean of net radiation increase by 5.5～13.3 W m-2, and glacial ablation increase by 152.7～492.1 mm w.e., which was larger than the measured by 8.6%～34.2%. \n(6) Climate change sensitivity test showed that mass balance was the most sensitive to air temperature compared with relative humidity, wind speed and precipitation. In the turbulence fluxes calculated by bulk aerodynamic method without stability correction, mass balance were overestimated by 16.9%, and it was therefore necessary to implement a stability correction. Sensible and latent heat fluxes increased together as aerodynamic roughness length rise, however which caused the change of mass balance very little because H and LE can cancel out each other. In the components of radiation, mass balance was the most sensitive to net shortwave radiation. Because mass balance was very sensitive to albedo, mass balance increased by 90% when albedo decreased by 0.1 in the accumulation zone, and mass balance varied by 36% when albedo changed by 0.1 in the ablation zone. |
| 中文关键词 | 老虎沟12号冰川 ; 地表特征参数 ; 能量-物质平衡模拟 ; 消融因素 ; 敏感性试验 |
| 英文关键词 | Laohugou Glacier No.12， land surface parameters，energy-mass balance simulation， ablation factors ，sensitivity test |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287107 |
| 推荐引用方式 GB/T 7714 | 孙维君. 祁连山老虎沟12号冰川能量-物质平衡模拟研究[D]. 中国科学院大学,2012. |
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