1. NetCDF (.nc) data introduction
Table of contents
1. NetCDF (.nc) data introduction
2. Data download of temperature and precipitation
NetCDF (network Common Data Form), the network common data format, is a file format used to store multidimensional scientific data (variables) such as temperature, humidity, air pressure, wind speed, and wind direction. In ArcGIS, you can display all of the above variables with a single dimension, such as time, by creating a layer or table view from a NetCDF file. Originally intended to be used to store data in meteorological sciences, it has now become the file format generated by many data acquisition software.
Data in a NetCDF file is stored in arrays. For example, the temperature of an area over time, or the temperature over time and altitude, is stored as a series of two-dimensional arrays.
Figure 1 is from the official account: GIS thinking
2. Data download of temperature and precipitation
Apply for an account through the National Earth System Science Data Center to download. National Earth System Science Data Center Data Details
Figure 2 1km resolution precipitation dataset interface
But this website can only download five data per day, and you need to apply every time. Although the application is very troublesome, it is very troublesome. As your most caring lamb, you must directly arrange a network disk link! ! Who made the lamb so cute and considerate!
Link: https://pan.baidu.com/s/1snH7JciIRlEbgg3M8O_mJA
Extraction code: 0946
Link: https://pan.baidu.com/s/1LZjtPYcoJZy56B8IQJGwjg
Extraction code: 0946 (you can leave a message to me if the joining link is invalid~)
3. Data processing process
1. For data import, first of all, you must put your files under a full English path ! ! ! ! Then under the toolbox [Multidimensional Tools] - [Create NetCDF], the specific operations are as follows:
2. Open [Properties] - [NetCDF], you can see the average temperature data of different months corresponding to different time latitudes of nc data. and has no spatial reference.
So how to extract the TIFF data images of each month through the model builder? We can do this with the help of ModelBuilder.
3.1 Drag the [NetCDF raster layer tool] into the editor interface and add the 2020 temperature year data. Then insert the iterator-for loop to automatically read and process the temperature data of different months.
3.2 There are twelve months in 2020, so the start value is 1, the end value is 36, and the increment value is 1 (month). After confirming, connect the for loop with NetCDF through the tool.
3.3 Then click [NetCDF raster layer tool], select "time" for "Dimensions", and enter "%value%" for the value. Be sure to type on the keyboard! !
3.4 [Data Management Tools] - [Raster] - [Raster Dataset] - [Copy Raster] and drag it into the editor. Note that the name must be % and %, and the format should be "TIFF".
3.5 [Data Management Tools] - [Projection and Transformation] - [Define Projection], the coordinate system can be selected according to the needs. If output is not required for copying and defining rasters, they can be processed as shown in the figure.
3.6 Finally, according to [spatial analyst tool] - [extract analysis] - [extract by mask], I extracted the area of Shanxi Province. Take a look at the final build results.
3.7 After running, you can see in the directory that all the data has been processed, and the final result is as shown.
References: ArcGIS processing multidimensional scientific data with NetCDF (.nc)
Summary of nc data processing methods, there is always one suitable for you!