Interplanetary Coronal Mass Ejection (ICME) Speed Forecasting - Geomagnetic Storms

A big potential threat and a dangerous event that might happen in your lifetime. Geomagnetic storms! On September 1st, 1859, the largest solar storm on record hit the earth. You may have already heard about the so-called Carrington event that happen back in 1859. The Carrington event was such a powerful solar storm that sat the telegraph papers on fire! The Coronal Mass Ejection (CME) starts on the surface of the sun where the intense magnetic field makes an arc shape of materials that have a high tendency to snap (well-known coronal mass ejection).

Problem Statment

A similar solar storm like the one in 1859, if happens today most likely wipes out the whole data on all computers due to the fact they are mostly not electromagnetic pulse protected. Intense solar storms ionize the earth's atmosphere which affects any magnetic communication such as cell phone, internet, etc. Such an event has the potential to cause a very large blackout entire planet The goal of this project is to forecast the solar storm's speed 18 days into the future using classical and modern tools (i.e. using 60 timestamps history). The ICME speed (V ICME km/s) record of the last 30 years is seen in the following figure (Image by author).

Data Collection and Preparation

The data was scraped from Near-Earth Interplanetary Coronal Mass Ejections Since January 1996 webpage here. I searched for the coronal mass ejection data set online and found the near-earth webpage which had the data from 1996 to 2020 (almost 550 rows). The data was a long table on one page with multiple headers, and I needed to use some python libraries that are used commonly in web scraping (i.e. beautiful soap).

• The data webpage HTML source file was downloaded and saved at the data folder and later was extracted in csv format. The first rows of raw data are seen below.

Exploratory Data Analysis

It is clear that the events reported by Huttunen et al have reported some outliers in the overall data set. It is seen that the Huttunen et al group have reported some very high ICME speeds. This observation opens room for investigating the whole data reported by their team to discover the reason behind these outliers. is there any difference between the measurement tools used by their team?

It is observed that the majority of ICME speed falls between 400 to 500 km/s and magnetic activity of -50nT to -60 nT (5th subplot). Note that, the Dst < -100 nT are considered severe solar storms (Zhang et al. 2007). Although there is some high ICME speed recorded above 450 km/s, however, the data shows both low and high magnetic index disturbance which makes it inconclusive. At the top-right side of the plot, a severe solar storm is seen with an ICME speed of around 800 km/s and Dst index of -99.

Statistical Analysis Results

Average solar wind speed is higher when Bidirectional suprathermal Electron strahls happen compare to when it does not.

• I rejected the null hypothesis with ttest_ind from stat library with a very small p-value, therefore the chance of getting type 1 error (false positive) is pretty low.

The average solar wind speed when Bidirectional suprathermal Electron strahls happen is not changed compared to when intense solar energetic particle event is happening.

• The observed difference in ICME speed is just due to noise. In another word, Although the data shows that when the intense solar energetic particle event is happening the solar wind speed is higher on average compared to when Bidirectional suprathermal Electron strahls is happening, the results However are not statistically significant. Upon checking out the number of data points with SEP, I found that I do have just 4 rows of data which is not enough to come up with a solid conclusion about the average ICME speed when an intense solar energetic particle event is going on.

Solar wind speed is higher on average when the forward fast shock happens.

• At least I don't have any evidence against it.

There is a significant correlation between solar wind speed and the mean magnetic field.

• I observed that those cases with the higher mean magnetic fields have generally had higher solar wind speeds and the correlation is statistically significant. The trend is ascending with a slope of 0.2 and it is significant statistically.

Solar Speed Forecasting

Solar Speed Forecasting 18 days into the future. I took two main approaches as follows to forecast the ICME speed.

• Time Series Univariate approach (also I took the supervised approach, applying ML algorithms including XGBoost, sequential, LR)
• Time Series Multivariate approach

Univariate approach: The ICME time series data timestamps were not evenly spaced. The data were resampled, considering the mean of timestamps (18 days) into the account. The classical forecasting methods including the autoregressive (AR) and autoregressive integrated moving average (ARIMA) were applied to univariate ICME speed data. I choose the ARIMA model which combines three methods including autoregressive, moving average, and integration. Two LSTM architecture models (Keras) were applied to time series data. In another part (03_04) of this work, the XGBoost, Linear regression, Sequential model using Keras and TensorFlow (data normalized using min-max scaler) were applied for supervised forecasting of univariate ICME speed data.

Multivariate approach: I made new data set using the pandas library and the shift method was used along with 60 lags. The goal is to use 60 lags (timestamps) to forecast the future timestamps (18 days into the future). In addition, I applied the LSTM model (Keras) model. The Sequential model using the TensorFlow library was applied considering two lags for ICME speed forecasting. The split fraction of 0.8 improved the model overall estimation MAE (no overfitting observed).

Results

ARIMA 5,1,0

ARIMA 5,1,0 Forecasting 18 days into the future (univar).

DNN supervised 18 days into the future (multivariate).

The DNN does not encounter overfitting however applying small networks is not helpful. Applying split fraction 0.8 results in improved MAE values. 2 lags (2*18 days) data was used for prediction next timestamps.

Supervised Sub-Project

I used the scrapped data and applied following steps to estimate the solar wind speed. This is a simple supervised ML project.

Steps are as follow:

1. Scraping data
2. Data cleansing
3. Remove missing values
4. Checking out data for duplicates
5. Check out columns unique values percentage
6. Checking out the Data distribution
7. Automatic Outlier Detection using Local Outlier Factor (LOF)
8. MiniMax transformer and features selection base on variance

9. MinMax & PowerTransformer on training data (avoiding data leakage)
10. MinMaxScaler, PowerTransformer & HuberRegressor on training data (avoiding data leakage)
11. Fit and Predict with whole pipeline (pipeline steps are: MinMaxScaler, PowerTransformer & HuberRegressor) achieved mean_absolute_error = 50.25320648218336

12. Categorical features selection
13. Applying OrdinalEncoder
14. Using categorical features and LinearRegression achieved MAE = 63

More development were done here. Several LSTM and RNN networks were used.