Merge pull request #60 from nsidc/update-for-25km-ss

Update for 25km ss

CHANGELOG.md

@@ -1,3 +1,9 @@
+# v0.4.0
+
+* Updates to support comparisons with CDR v4 code. The CDR v4 code was also
+  based on code originally authored by Goddard, but had some minior differences.
+
+
 # v0.3.2
 
 * Update `pm_tb_data` dependency to v0.4.0

README.md

@@ -16,6 +16,18 @@ For more informaton about Bootstrap and NASA Team algorithms, see [Descriptions
 of and Differences between the NASA Team and Bootstrap
 Algorithms](https://nsidc.org/data/user-resources/help-center/descriptions-and-differences-between-nasa-team-and-bootstrap)
 
+There is a long history to this project! Comments may indicate references to
+"CDR v4" or "Goddard". In short:
+
+* NASA Goddard Space Flight Center (GSFC) originally developed the algorithms
+* NSIDC developed `pmalgos` (currently private repo) in the late ~1990s from the
+  code Goddard developed.
+* More recently, NSIDC developed `cdralgos` (private repo) based on `pmalgos`
+  _and_ newly updated code from Goddard (Goddard contnued to develop and run
+  their own code)
+* Now, this iteration, which seeks to replicate the sea ice concentration
+  algorithms in Python, and in a modular fashion.
+
 
 ## Level of Support
 

pm_icecon/_types.py

@@ -12,3 +12,8 @@
     "00",  # SMMR
     "a2l1c",
 ]
+
+LandSpilloverMethods = Literal[
+    "BT_NT",  # Use both the BT and NT spillover methods, as per CDRv4
+    "NT2",  # Use only the NT2 land spillover method
+]