Changeset 2715 in lmdz_wrf for trunk

Timestamp:

Sep 30, 2019, 5:57:34 AM (5 years ago)

Author:

lfita

Message:

Adding:

• `snr_K08': Function to compute the signal-to-noise-ratio after Kendon et al., 2008
• `gamma_TS_S99': Function to compute a gamma factor from which construct an equivalent T-student distribution from a given numbers of freedom and apair of sigma values after von Storch, H. and Zwiers, F. W. (1999)

File:

• trunk/tools/generic_tools.py (modified) (3 diffs)

trunk/tools/generic_tools.py

@@ -130 +130 @@
 # fromanydate_CFYmd: Function to transform from any string format of date to Y-m-d used in 
 #   CF-conventions
+# gamma_TS_S99: Function to compute a gamma factor from which construct an equivalent 
+#    T-student distribution from a given numbers of freedom and apair of sigma values
+#    after von Storch, H. and Zwiers, F. W. (1999)
 # gen_impose_gregorian: Function to impose gregorian calendar to a series of times with a 
 #   non-standard calendar independently from datetime (imposes yr > 1900)
@@ -226 +229 @@
 # sign: Function to provide the sign of a number
 # singleline_printing_class: Function to print all the values of a given class in a single line to be parseavel
+# snr_K08: Function to compute the signal-to-noise-ratio after Kendon et al., 2008
 # stagger_unstagger: Function to de-stagger a variable
 # stats_Slist: Function to provide extremes from a string as a list separated by a given character
@@ -17183 +17187 @@
     return factor, vals2
 
+def snr_K08(signal,sigx,sigy):
+    """ Function to compute the signal-to-noise-ratio after Kendon et al., 2008, J. 
+        Climate, 21(17):4280–4297
+      signal: signal to find the noise ratio
+      sigx, sigy: 2 standard deviation to compute the noise
+    """
+    fname = 'snr_K08'
+
+    snr = signal/(np.sqrt(sigx**2+sigy**2)/2.)
+
+    return snr
+
+def gamma_TS_S99(counts, sigx, sigy):
+    """ Function to compute a gamma factor from which construct an equivalent 
+      T-student distribution from a given numbers of freedom and apair of sigma values
+        after von Storch, H. and Zwiers, F. W. (1999). Statistical analysis in 
+          climate research. Cambridge University Press, page 484.
+      counts: number of degrees of freedom
+      sigx, sigy: pair of standard deviation
+    """
+    fname = 'gamma_TS_S99'
+
+    gamma = (counts-1)*( (1+(sigy/sigx)**2)**2/(1+(sigy/sigx)**4) )
+
+    return gamma
+
 #quit()