Add figure captions and references to the clouds extension

For #20

clouds/clouds/cesm_cldhgh_ann.py

@@ -7,7 +7,12 @@ from netCDF4 import Dataset
 from livvkit.util import elements as el
 
 
-describe = """CESM_cldhgh_ANN plot."""
+describe = """
+Climatological annual average of high cloud cover over Greenland 
+for CESM (left), ISCCP (middle; Rossow and Schiffer, 1999), and CLOUDSAT (right; 
+Kay and Gettelman, 2009).  The black solid lines denote the 0, 1000, 2000, and 
+3000 meter Greenland ice sheet elevation contours as seen by CESM.
+"""
 
 
 def make_plot(config, out_path='.'):

clouds/clouds/cesm_cldlow_ann.py

@@ -7,7 +7,12 @@ from netCDF4 import Dataset
 from livvkit.util import elements as el
 
 
-describe = """CESM_cldlow_ANN plot."""
+describe = """
+Climatological annual average of low cloud cover over Greenland 
+for CESM (left), ISCCP (middle; Rossow and Schiffer, 1999), and CLOUDSAT (right; 
+Kay and Gettelman, 2009).  The black solid lines denote the 0, 1000, 2000, and 
+3000 meter Greenland ice sheet elevation contours as seen by CESM.
+"""
 
 
 def make_plot(config, out_path='.'):

clouds/clouds/cesm_cldtot_ann.py

@@ -7,7 +7,12 @@ from netCDF4 import Dataset
 from livvkit.util import elements as el
 
 
-describe = """CESM_cldtot_ANN plot."""
+describe = """
+Climatological annual average of cloud cover over Greenland 
+for CESM (left), ISCCP (middle; Rossow and Schiffer, 1999), and CLOUDSAT (right; 
+Kay and Gettelman, 2009).  The black solid lines denote the 0, 1000, 2000, and 
+3000 meter Greenland ice sheet elevation contours as seen by CESM.
+"""
 
 
 def make_plot(config, out_path='.'):

clouds/clouds/yearly_cycle_cldhgh.py

@@ -7,7 +7,11 @@ from netCDF4 import Dataset
 from livvkit.util import elements as el
 
 
-describe = """yearly_cycle_cldhgh plot."""
+describe = """
+Climatological monthly average of total high cloud cover over Greenland 
+for CESM (red), ISCCP (green; Rossow and Schiffer, 1999), and CLOUDSAT (cyan; 
+Kay and Gettelman, 2009).
+"""
 
 
 def make_plot(config, out_path='.'):

clouds/clouds/yearly_cycle_cldlow.py

@@ -7,7 +7,11 @@ from netCDF4 import Dataset
 from livvkit.util import elements as el
 
 
-describe = """yearly_cycle_cldlow plot."""
+describe = """
+Climatological monthly average of total low cloud cover over Greenland 
+for CESM (red), ISCCP (green; Rossow and Schiffer, 1999), and CLOUDSAT (cyan; 
+Kay and Gettelman, 2009).
+"""
 
 
 def make_plot(config, out_path='.'):

clouds/clouds/yearly_cycle_cldtot.py

@@ -7,7 +7,11 @@ from netCDF4 import Dataset
 from livvkit.util import elements as el
 
 
-describe = """yearly_cycle_cldtot plot."""
+describe = """
+Climatological monthly average of total cloud cover over Greenland 
+for CESM (red), ISCCP (green; Rossow and Schiffer, 1999), and CLOUDSAT (cyan; 
+Kay and Gettelman, 2009).
+"""
 
 
 def make_plot(config, out_path='.'):

clouds/clouds_cesm.bib

@@ -9,3 +9,24 @@
     PAGES = {854--869},
     YEAR = {2017},
 }
+
+@Article{isccp99,
+    AUTHOR = {R. B. Rossow and R.A. Schiffer},
+    title = {Advances in understanding clouds from ISCCP},
+    YEAR = {1999},
+    JOURNAL = {Bulletin of the American Meteorological Society},
+    VOLUME = {80},
+    DOI = {10.1175/1520-0477(1999)080<2261:AIUCFI>2.0.CO;2},
+    PAGES  = {2261--2287}
+}
+
+@article {kg09,
+    AUTHOR = {Kay, Jennifer E. and Gettelman, Andrew},
+    TITLE = {Cloud influence on and response to seasonal Arctic sea ice loss},
+    JOURNAL = {Journal of Geophysical Research: Atmospheres},
+    VOLUME = {114},
+    NUMBER = {D18},
+    DOI = {10.1029/2009JD011773},
+    YEAR = {2009},
+    NOTE = {D18204},
+}
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