rvn_rvt_met cleanup & addition to rvn_utilities

[aviolinist]

NEW USER NOTES

Once these are approved, we can supply more details in the documentation.

user-supplied data frame should have following column names:

"lat" - latitude
"lon" - longitude
"elev" - elevation of met station (masl)
"date" - in YYYY-MM-DD format

supported data types, each in its own named column: WEATHERCAN columns:

"total_snow"  -  mm/d
"max_temp"  -  C
"min_temp"  -  C
"total_precip"  - mm/d

RAVEN columns (based on table C.2 in manual - # not implemented yet):

#"PRECIP_DAILY_AVE" - mm/d
#"PRECIP_5DAY" - mm/d
"SNOW_FRAC" - [0..1]
"SNOWFALL" - mm/d
"RAINFALL" - mm/d
#"RECHARGE" - mm/d

"TEMP_AVE" - C
#"TEMP_DAILY_AVE" - C
"TEMP_MIN" OR "TEMP_DAILY_MIN" - C
"TEMP_MAX" OR "TEMP_DAILY_MAX" - C
#"TEMP_MONTH_MAX" - C
#"TEMP_MONTH_MIN" - C
#"TEMP_MONTH_AVE" - C
#"TEMP_AVE_UNC" - C
#"TEMP_MAX_UNC" - C
#"TEMP_MIN_UNC" - C
#"AIR_DENS" - kg/m3
#"AIR_PRES" - kPa
"REL_HUMIDITY" - [0..1]

"ET_RADIA" - MJ/m2/d
"SHORTWAVE" OR "SW_RADIA" - MJ/m2/d
#"SW_RADIA_NET" - MJ/m2/d
#"LW_RADIA_NET" - MJ/m2/d
"LW_INCOMING" - MJ/m2/d
#"CLOUD_COVER" - [0..1]

"WIND_VEL" - m/s
"PET" - mm/d
"OW_PET" - mm/d
#"PET_MONTH_AVE" - mm/d
"POTENTIAL_MELT" - mm/d
#"SUBDAILY_CORR" - [-]

ADDITIONAL NOTES

• timeseries should be evenly spaced (Irregular intervals is not supported for met data)
• total snowfall from weathercan is given in cm, but convention is mm (unit conversion previously built in but now commented out - "incompatible with data density assumption"?) ... perhaps we should leave this for the user to pre-process?

OUTSTANDING TASKS

• Monthly data format support to come later (e.g., PET, LAI, etc.)
• documentation tentatively updated - needs review: can "TOTAL_PRECIP", "RAINFALL", and "SNOWFALL" all be written into the same rvt? If not, we need to throw an error message.

PATCH NOTES

Function now supports writing generic met data with 1 or more parameters - Fixes #63

• removed forcing_set feature to support generic writing of more parameter combinations (was this also a control to avoid writing "TOTAL_PRECIP", "RAINFALL", and "SNOWFALL" in the same file? If so, we need to implement a new error message to catch this)

.rvt writing mechanics now decoupled from rvn_rvt_write:

• standalone source code now writes in :Data format when only 1 parameter is supplied and :MultiData format when more than 1 parameter is supplied.

Added two mapping lists in rvn_utilities:

• rvn_weathercan_mapping (sets EC data column names to standard Raven convention)
• rvn_met_data_mapping (supplies aliases with matching Raven units)

Function now ignores extra columns of data for unsupported met data types (e.g., QC flags)

Constrained unique identifier for multiple weather stations to only "station_name" (previously included "station_id", which may not exist for non-EC datasets)

Minor adjustments to improve display and specifics of error messages:

• added "RavenR::rvn_ts_infill" as suggestion for fixing irregular time series gaps
• specifically identifies instance of supply hourly data from weathercan (looks for "time" column in data frame)
• warning message when skipping columns (unsupported data types)