OriginLab Technical Support

3/9/2022

7/5/2022

180

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NetCDF_Dat...is.opx

1.01

Perform analysis on NetCDF data.

**PURPOSE**

This app can be used to perform analysis on NetCDF data including **Sen's Slope**, **Mann-Kendall Test** along the time direction, **Linear Fit** and **Correlation Coefficient** between two NetCDF data.

**INSTALLATION**

Download the file *NetCDF_Data_Analysis.opx*, and then drag-and-drop onto the Origin workspace. An icon will appear in the **Apps Gallery** window.

NOTE: This tool requires OriginPro.

**OPERATION**

- Make an MBook for NetCDF data active. Click on the
**NetCDF Data Analysis**icon in the**Apps Gallery**window. A dialog with six buttons will appear.- Click the first
**Sen's Slope**button.**Sen's slope**result will be calculated in a new MBook. - Click the second
**Mann-Kendall Test**button. Three matrices will be created in the new MBook including Mann-Kendall Test's statistic, P-value and significant flag (1 represents significant for alpha=0.05). - Click the third
**Linear Fit for Two NetCDF Files**button. It will use the active MSheet as the first NetCDF data, and pop up a dialog to choose the second NetCDF data, the second data can be a NetCDF data in another MSheet or data in a column with the same size as that of time for the first NetCDF data. Two matrices will be created in the new MBook including the intercepts and slopes. - Click the 4th
**Correlation between Two NetCDF Data**button. It will use the active MSheet as the first NetCDF data, and pop up a dialog to choose the second data. In the dialog, choose**Lag for 1st Data**or**2nd Data**, and set a value in**Lags**edit box to specify the lag between two data in the calculation of correlation. Two matrices for the correlation and significance of the correlation will be created in the new MBook. In the**Show Correlations**dropdown list, three options are available:**Output All**,**Set Missing for Insignificance Correlations**and**Output Significance Flag**. When the last two options are chosen,**Significance Level**edit box is available. For the 2nd option, correlations whose significance levels are greater than the specified value will be set missing values. For the 3rd option, the significance matrix will be replaced with 0(insignificance) or 1 (significance). Note that If the NetCDF data is large, it may be slow to read data in MBook. Progress is shown in the status bar. And when it is finished, a message box will open.

- Click the first
- Click the 5th
**OK**button. The dialog for buttons will be closed. The MBook for the result will be activated.

**SAMPLE OPJU FILE**

This app provides a sample OPJU file. Right click on the **NetCDF Data Analysis** icon in the **Apps Gallery** window, and choose **Show Samples Folder** from the short-cut menu. A folder will open. Drag-and-drop the project file *NetCDFDASample.opju* from the folder onto Origin. The **Notes** window in the project shows detailed steps. Note: If you wish to save the OPJU after changing, it is recommended that you save to a different folder location (e.g. **User Files Folder**).

**ALGORITHM**

- Sen's Slope

\(Sen's Slope=Median\{\frac{x_j-x_i}{j-i},\ i< j\}\) - Mann-Kendall Test

Statistic: \(S=\displaystyle \sum_{i=1}^{n-1} \displaystyle \sum_{j=i+1}^{n} sign(x_j - x_i)\)

Variance: \(var=\frac{1}{18}[n(n-1)(2n+5)-\displaystyle \sum_t f_t(f_t-1)(2f_t+5)]\)

where*n*is size along the time direction, and*t*is the set of tied ranks, and*f*is number of times for the tied rank._{t}

Normal distribution*z*for*n*>10: \(z=\begin{cases} \frac{S-1}{\sqrt{var}} , & S>0 \\ 0 , & S=0 \\ \frac{S+1}{\sqrt{var}} , & S<0 \end{cases}\) - Linear Fit

Perform linear fit along time direction for two NetCDF data. - Correlation

Calculate correlation coefficients along time direction between two NetCDF data.

7/5/2022 v1.01 Fixed error message for split MSheet.

07/20/2022 | Andrew | This is nice! |