phenology

phenology.py

import matplotlib.pyplot as plt
import numpy as np
from phenology import *

data2011 = np.loadtxt('/Users/User/data2011.txt')
# Define variables
doy = data2011[:,0]
temp = data2011[:,1]

tbase = 10.
tmax = 40.
# Calculate AGDD
agdd  = calculate_gdd( temp, tbase=tbase, tmax=tmax )
# First subplot is Hainich (DE)
fig = plt.figure()
plt.plot(doy, temp, '-r')
plt.plot(doy, agdd, 'g')
plt.xlabel("DoY")
plt.show()

You already have temperature so just use the calculate_gdd function from phenology library to calculate gdd and then plot it with your data.