Heard Island glacier fluctuations and climatic change

This report describes and presents all the data gathered on Brown Glacier during the 2000 field season. The goal of the study (ASAC project 1158) was to characterize one of the Heard Island glaciers that has a relatively simple geometry and is easy to work on. A land terminating glacier was chosen because of the larger expected response to climate change. The plan was to collect data on the dynamic characteristics, mass balance, sub-glacial topography and recent fluctuations of a Heard Island glacier. The data will ultimately be used to construct and validate a numerical model of the glacier. The model will be used to simulate the possible cause of the glacier fluctuations, and help to derive a climate-proxy record for this remote and sensitive area.The study of the morphology, dynamics and mass balance of the Brown Glacier on the northeastern side of Heard Island was undertaken between mid-October and late November 2000. An ANARE field party, operating from a small field camp near the foot of the glacier, comprised three glaciologists (M.T., A.R. and D.T.) until early November, with two staying for the full period (M.T. and D.T.). This group was independent of two other ANARE field camps located at Atlas Cove and Spit Bay.The following field measurements were successfully completed:A differential GPS survey of the surface elevation along the centre-line of the glacier (from 1 100 m elevation to the snout below 200 m) and across five transverse sections,A differential GPS survey of the location of the present snout of the glacier, and the 1947 lateral moraines,Bathymetric measurements of the lagoon formed by retreat of the glacier since the 1950's,Detailed ice thickness measurements (with a portable radio echo-sounder) across a transverse profile of the glacier at 500 m elevation, and spot thickness measurements across three other profiles,Surface ice velocity measurements along the centre-line of the glacier (10 locations) and along two transverse sections at 500 m and 400 m elevation (five and four locations respectively). Most of these sites were measured over two epochs, and time varying velocity measurements were made for nearly four weeks at one site,Surface mass balance measurements during November at the location of all velocity measurements. Other members of the ANARE party made additional measurements in mid-January,Temperature and density measurements, and snow sampling from a pit and a crevasse,Detailed meteorological measurements from a temporary automatic weather station (AWS) on the glacier surface (at 500 m elevation) during November, and ongoing satellite-relayed meteorological measurements from a larger AWS on rock adjoining the Brown Glacier (~550 m elevation). The glacier surface measurements included half-hourly surface height measurements with an acoustic ranger to record short time scale changes in surface mass budget.Data Files available:DEM Folder contentsdem.ascHeard DEM in ASCII format, obtained from the AADallprof.datall kinematic GPS profilesbrownarea.datHeard DEM cropped to the Brown Glacier areabrownpoints.datPoints surveyed with static GPS methodsdem.datHeard DEM without headernewdem.datBrown Glacier area DEM corrected with GPS profilesoldglacier.dat1947 Glacier outlineoutline.datGlacier outline, digitized from newdem.dat*.mvarious Matlab programs to adjust the DEMcreatedem.mMatlab program used for final DEM adjustmentdem.mMatlab program to display and crop the Heard DEMdrawdem.mMatlab program to display a map (with various options)icelost.mMatlab program to calculate volume changedem.prjProjection parameters for Heard Island DEM*.profkinematic GPS profiles in ASCII formatGlacier velocities folder contentsdaily.*ASCII and Excel file of daily velocities measured at BG35GPSpoints.*ASCII and Excel file of index points surveyed with static GPSindex.mMatlab program to display velocitiesindexpoints.txtFile with velocity data used in index.mIsotope Analysis folder contentsDel018.xlsExcel file containing Oxygen isotope data from BG35 and crevassekinematic profiles folder contents*.txtall the kinematic GPS profiles in ASCII formatLagoon bathymetry folder contentslagoon.mMatlab program to reduce bathymetry data in bathy.txtlagoon.figMatlab figure showing the bathymetry databathy.txtASCII data file for use in lagoon.mshore.txtASCII data file for the surveyed shore linebathymetry.xlsExcel file with bathymetry dataMatlab folder contentsareasize.mprogram to calculate the area enclosed in a polygonchkload.mprogram to load a file with additional optionscircle.mfunction to draw a circle (used in index.m)RES folder contentsbg**.datRES raw data (format is specified in RES.m help)bg**bottom.datDigitized bed from RES returnsbg**.resprocessed RES files (format specified in RES.m help)RES.mMatlab program to reduce RES datadrwelip.mfitline.mMatlab programs used by RES.mWeather folder contentsrock_aws.xlsoriginal weather data files from the rock AWSglacier_aws.xlsoriginal weather data files from the glacier AWSsnow_surface.xlssnow surface height measurements from the bamboo poles at theindex sites (longitudinal and transverse).

本报告描述并呈现了2000年野外季期间针对布朗冰川（Brown Glacier）收集的全部数据集。本研究（ASAC项目1158）的目标是表征赫德岛（Heard Island）上一座几何形态相对简单、易于开展研究的冰川。研究选择陆地终止型冰川（land terminating glacier），因其预期对气候变化的响应更为显著。本次研究计划收集该赫德岛冰川的动力学特征、物质平衡（mass balance）、冰下地形以及近期波动情况相关数据，最终将用于构建并验证该冰川的数值模型，以模拟冰川波动的潜在成因，并为这片偏远且生态敏感的区域推导气候代用记录。

2000年10月中旬至11月下旬，针对赫德岛东北部的布朗冰川的形态、动力学与物质平衡开展了研究。由三名冰川学家（M.T.、A.R.、D.T.）组成的澳大利亚国家南极研究探险队（Australian National Antarctic Research Expeditions, ANARE）野外工作组，在冰川脚下附近的小型野外营地开展工作，11月初前共有三名成员，其中两人（M.T.和D.T.）全程参与了野外工作。该工作组独立于另外两处位于阿特拉斯湾（Atlas Cove）和斯皮特湾（Spit Bay）的ANARE野外营地。

本次野外工作顺利完成了以下测量任务：
1. 沿冰川中心线（海拔1100米至海拔200米以下的冰舌）及5条横向剖面开展表面高程差分GPS（differential GPS）测量；
2. 对冰川当前冰舌位置以及1947年侧碛（lateral moraines）的位置开展差分GPS测量；
3. 对自20世纪50年代以来冰川退缩形成的潟湖开展测深（bathymetric）测量；
4. 在海拔500米处的冰川横向剖面上开展详细冰厚测量（使用便携式无线电回声测深仪），并在另外3条剖面上开展单点冰厚测量；
5. 沿冰川中心线（10个测点）以及海拔500米、400米处的两条横向剖面（分别对应5个和4个测点）开展表面冰流速测量。多数测点进行了两期测量，其中一个测点开展了近四周的时变流速监测；
6. 11月期间在所有流速测点开展表面物质平衡测量。另有ANARE工作组其他成员于1月中旬开展了补充测量；
7. 开展温度与密度测量，并从冰坑和裂缝中采集雪样；
8. 11月期间在冰川表面海拔500米处搭建临时自动气象站（Automatic Weather Station, AWS）开展详细气象观测，同时通过卫星中继获取毗邻布朗冰川的岩石区域（海拔约550米）内大型自动气象站的持续气象数据。冰川表面观测还包括使用声学测距仪每半小时记录一次表面高程，以监测表面物质收支的短时尺度变化。

### 可用数据文件
#### DEM文件夹内容
- dem.asc：澳大利亚南极数据中心（Australian Antarctic Data Centre, AAD）提供的赫德岛数字高程模型（Digital Elevation Model, DEM），格式为ASCII
- allprof.dat：全部动态GPS剖面数据
- brownarea.dat：裁剪至布朗冰川区域的赫德岛DEM
- brownpoints.dat：采用静态GPS方法测量的测点数据
- dem.dat：无头部信息的赫德岛DEM
- newdem.dat：结合GPS剖面数据修正后的布朗冰川区域DEM
- oldglacier.dat：1947年冰川轮廓数据
- outline.dat：从newdem.dat数字化得到的冰川轮廓
- *.m：用于调整DEM的各类Matlab程序
- createdem.m：用于最终DEM调整的Matlab程序
- dem.m：用于显示和裁剪赫德岛DEM的Matlab程序
- drawdem.m：用于绘制地图（支持多种选项）的Matlab程序
- icelost.m：用于计算冰体体积变化的Matlab程序
- dem.prj：赫德岛DEM的投影参数文件
- *.prof：格式为ASCII的动态GPS剖面数据

#### 冰川流速文件夹内容
- daily.*：在BG35测点获取的每日流速数据的ASCII与Excel文件
- GPSpoints.*：采用静态GPS方法测量的索引测点数据的ASCII与Excel文件
- index.m：用于显示流速数据的Matlab程序
- indexpoints.txt：index.m中使用的流速数据文件

#### 同位素分析文件夹内容
- Del018.xls：包含BG35测点与裂缝处氧同位素数据的Excel文件

#### 动态GPS剖面文件夹内容
- *.txt：格式为ASCII的全部动态GPS剖面数据

#### 潟湖测深文件夹内容
- lagoon.m：用于处理bathy.txt中测深数据的Matlab程序
- lagoon.fig：展示测深数据的Matlab图形文件
- bathy.txt：供lagoon.m使用的ASCII格式测深数据文件
- shore.txt：经测量得到的岸线ASCII数据文件
- bathymetry.xls：包含测深数据的Excel文件

#### Matlab工具文件夹内容
- areasize.m：用于计算多边形包围区域面积的程序
- chkload.m：用于以附加选项加载文件的程序
- circle.m：用于绘制圆形的函数（在index.m中使用）

#### RES文件夹内容
- bg**.dat：RES原始数据（格式详见RES.m帮助文档）
- bg**bottom.dat：从RES回波数据数字化得到的冰下基岩数据
- bg**.res：经过处理的RES文件（格式详见RES.m帮助文档）
- RES.m：用于处理RES数据的Matlab程序
- drwelip.m、fitline.m：RES.m使用的Matlab程序

#### 气象文件夹内容
- rock_aws.xls：来自岩石区域自动气象站的原始气象数据文件
- glacier_aws.xls：来自冰川表面自动气象站的原始气象数据文件
- snow_surface.xls：来自测点处竹杆的雪面高程测量数据（包括纵向与横向剖面）