You may have heard of global warming, which claims that temperature is rising steadily each year. Since pressure is another thermodynamic variable, we may expect pressure also to follow a trend. The complete code for this recipe is in the annual.py file in this book's code bundle:
import numpy as np
import matplotlib.pyplot as plt
data = np.load('cbk12.npy')
# Multiply to get hPa values
avgs = .1 * data[:,1]
highs = .1 * data[:,2]
lows = .1 * data[:,3]
# Filter out 0 values
avgs = np.ma.array(avgs, mask = avgs == 0)
lows = np.ma.array(lows, mask = lows == 0)
highs = np.ma.array(highs, mask = highs == 0)
# Get years
years = data[:,0]/10000
# Initialize annual stats arrays
y_range = np.arange(1901, 2014)
nyears = len(y_range)
y_avgs = np.zeros(nyears)
y_highs = np.zeros(nyears)
y_lows = np.zeros(nyears)
# Compute stats
for year in y_range:
indices = np.where(year == years)
y_avgs[year - 1901] = np.mean(avgs[indices])
y_highs[year...