Satellite-Based Air Quality Mapping in Target Regions 卫星数据绘制特定区域的空气污染地图

11月 25 2018 Research 7 分钟 read (About 1016 words)

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, PM_2.5. 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.

Plotting topography map with hillshade 绘制带阴影高光的地形图

11月 9 2018 Tech 3 分钟 read (About 389 words)

Hillshade is the representation of the earth’s surface under the radiation of sun. A terrain raster data can be better visualized by adding the information of hillshades. This blog will introduce some procrdures to overlay the hillshade with terrain for a nice picture.

Post processing of FLEXPART-WRF output

11月 6 2018 Research 7 分钟 read (About 1062 words)

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

在低版本Linux安装科学计算库的曲折之路

9月 4 2018 Research 11 分钟 read (About 1665 words)

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。

FLEXPART installation notes

8月 10 2018 Research 9 分钟 read (About 1318 words)

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

Useful python scripts for daily uses

7月 22 2018 Tech 44 分钟 read (About 6557 words)

Welcome to my collection of Python scripts and code snippets for everyday use. This document contains a variety of scripts and code snippets that can be used to automate repetitive tasks, process data, and perform various other operations. Whether you are a beginner or an experienced Python programmer, this collection of scripts and code snippets will provide you with useful tools and shortcuts for your everyday work.

In this document, you will find code snippets and scripts for tasks such as:

Data processing
File manipulation
Web scraping
Automating tasks
And more!

This document is organized into sections for easy navigation, so you can quickly find the script or code snippet that you need. Many of them were collected from stackoverflow.

On 2022.03.31, I re-organize all the scripts into Python 3.x version and post again.
On 2023.02.12, I edited the whole content with help from ChatGPT

中国空气质量历史数据整理(HDF5格式)

4月 4 2018 Research 9 分钟 read (About 1353 words)

全国空气质量历史数据是大气环境研究的重要基础资料，而我国官方平台仅提供实时监测信息，而且还只支持IE浏览器(╮(╯_╰)╭)。

我曾尝试采用爬虫工具获取并存储逐时信息，但限于权限，未能在实验室服务器上连续长时间运行。互联网上直接提供数据或API端口的网站有很多，如环境云，PM25.in, 青悦开放环境数据中心等。其中，beijingair最具分享精神,提供了2013年至今的详尽历史数据，且完全免费。

由衷感谢@王_晓磊的出色工作和无私分享，极大地推动了我国环境数据的公开与透明。其数据格式为每日一份csv文件存储当日所有站点/城市的逐时信息。在长时间尺度的数据分析时，需逐一阅读各原始文件。此处，我考虑将全年数据文件整合为多维度数据存储格式(HDF5)文件，便于调用和处理。

利用Python获取地理信息并可视化

11月 6 2017 Tech 10 分钟 read (About 1480 words)

网络中有丰富的地理信息数据资源，此处介绍我采用Python工具实现地形地貌、行政区划、城市交通路网等数据获取及可视化的部分实例，供大家参考学习。

MODIS卫星火点数据的简易处理与可视化分析

6月 22 2017 Research 8 分钟 read (About 1176 words)

提要：此文介绍利用Python语言处理NASA MODIS火点数据（Global Monthly Fire Location Product，MCD14ML），可实现的基本功能包括:（1）特定时期的火点信息提取;（2）特定区域内的火点信息提取;（3）火点密度空间分布的计算与可视化表达

[WRF-Chem学习笔记②]仅含沙尘源的模拟练习

9月 5 2016 Research 3 分钟 read (About 378 words)

本文是我学习官网练习的记录，其模拟区域为北非，中东以及欧洲部分地区，无嵌套设置。共分为5个练习，分别为:

初始场添加沙尘排放源的模拟

采用GOCART全球气溶胶排放清单的模拟

加入生物源排放的化学模拟(MEGAN引入)

加入气溶胶直接/间接辐射效应的模拟

WRF-Chem数值预报实验

下文记录Exercise 1的流程和注意事项

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