Research

我一直想对茶叶中复杂的化学成分充满兴趣。实验室有同事需要测量生物气溶胶样品(如孢子、真菌等),借助这次协助其调试维护质谱仪器的机会,开展了一项课外探索:使用高分辨率质谱方法,探索不同类型茶叶在分子层面是否具有可辨识的特征。

本次尝试使用非靶向直接注入分析,结合Orbitrap与TOF两台质谱,评估我构建的分析流程在实际复杂样品中的表现。

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Xarray provides pandas-level convenience for working with ultidimensional data. Xarray has two fundamental data structure: a DataArray, which holds a single multi-dimensional variable and its coordinates;
a Dataset, which holds multiple variables that potentially share the same coordinates.

Moreover, a DataArray has four attributes:

  • values: a numpy.ndarray holding the array’s values (矩阵数值,例如地表温度具体数值)
  • dims: dimension names for each axis (e.g., (‘x’, ‘y’, ‘z’)) (维度名称,如经度、纬度、垂直分层、时间等)
  • coords: a dict-like container of arrays (coordinates) that label each * point (e.g., 1-dimensional arrays of numbers, datetime objects or strings) (各维度坐标体系,如时间序列)
  • attrs: an OrderedDict to hold arbitrary metadata (attributes) (对各属性的描述)

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部分互联网资料仅提供在线预览,无法直接下载。若预览系统设计欠佳,或限于网速内容加载过慢,都会对阅读体验造成严重影响。在此分别以国家自然基金研究报告和学位论文为例,介绍两种不同的下载合成方法,供有需要的老师同学们参考。欢迎大家提出宝贵意见。

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When you’ve got the all the files from WRF simulations, you might want to merge them without the spin-up frames (to reach a balanced state with the boundary conditions, i.e., 12 hours for a 5-day simulation). Meanwhile, the variables/grids which are not focused on can be ignore. Therefore, a general workflow in pythonic way is presented. I will also rewritten this function as my first Python Package. Please note the updates on my website.

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I’m writing today about downloading, handling, and plotting satellite derived air pollution maps with cartopy and fiona using Python. One key task in this post is to clip a raster-like (2-d array) dataset with a polygon in pure Python environment (i.e., no need for ArcGIS or QGIS GUI-based software).

The satellite sensor can offer critical supplementary data of several atmospheric species, e.g., SO2, NO2, PM2.5. Comparaing to ground-based monitoring which might be sparse in some areas (e.g., Africa, South America, oceans), the satellite observation offers a full picture for better understanding the spatiotemporal patterns of some air pollutants.

Below is an excerpt of a NO2 column maps within Chengyu urabn agglomeration in China.

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In this post, I present some simple programs written in Python for post-processing the flexpart-wrf output.

It mainly contains several aspects, data merging, data processing and data visualization. I will also show some tips tp creat self-defined colormaps for nice plots.

PS: All th codes are also uploaded in my GitHub respority PyFlex

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以前处理WRF等气象模型的输出文件,总是下载到本地电脑做后处理分析。由于计算量不断增加,模拟生成的文件往往会很大。因而,我考虑直接在服务器中处理数据。本来是很容易的事情,却因为课题组服务器的系统版本较旧,在安装有关工具时耗去了不少时间。在此记录我的探索过程。

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FLEXPART is a Lagrangian particle dispersion model (LPDM) developed by Norwegian Institute of Air Research, Norway. It allows researchers to simulate the long-range transportation, diffusion, dry/wet deposition processes of atmospheric spcecies from their sources. It also can be utilized for backward calculation based on the observation of receptor to anaysis source-receptor relationships.

This model is coded following the Fortran 95 standard, and can be freely download from the page here. Flexpart 8.x/9.x is easy for compilation following the offical reference. I noticed that netCDF-format output (which would make the post-processing easier compared to the original binary output files) has been merged in the newer veision. Therefore, I tried to compile FLEXPART 10.0 beta version in the Linux system, while lots of issues appeared. My installing steps are listed as follows

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