SWE and soil moisture parameters are recorded in Standard Hydrometeorological Exchange Format (SHEF), as used by the US National Weather Service to distribute forecasted and point data for use in hydrologic operations. SHEF messages are presented in tab-delimited ASCII format. An example file structure is given below. The first 14 rows are header information (rows 12-13 are column headers). General comments are included after the data (between rows marked ‘.END' and ‘NNNN').

SRUS43 KMSR 191627
RRMASP
.BR GAMMA 020219 /SAIRF/SWIRF
:TO ------ Service Hydrologist (Please give HARDCOPY to SH)
:FROM ---- Tom Carroll, (952) 361-6610 ext 225, Minneapolis , Minnesota
:Visit our web page at www.nohrsc.noaa.gov
:SUBJECT - AIRBORNE SNOW WATER EQUIVALENT DATA 020219162753
:-----------------------------------------------------------------------
: Total No. of flight lines sent = 7
:-----------------------------------------------------------------------
:Line Survey %SC SWE SWE %SM Est Fall %SM Pilot
:No. Date (in) (35%) (M) Typ Date (F) Remarks
:=======================================================================
CO102 DY020219 / 100 / 3.1 : 2.2, 20 SE 0 , 20 LARGE SNOW DRIFTS
CO125 DY020219 / 100 / 3.2 : 2.3, 20 SE 0 , 20 MTN OBSCUR.
CO126 DY020219 / 100 / 2.3 : 1.4, 20 SE 0 , 20 DUSTING OF NEW SNOW
EX101 DY020219 / 100 / 3.0 : 1.9, 16 GM 10922 , 16 OLDER SNOW
EX102 DY020219 / 100 / 4.7 : 4.4, 28 GM 10922 , 28 SAGE BRUSH THROUGH S
EX120 DY020219 / 100 / 3.7 : 3.1, 24 GM 10922 , 24 MTN OBSCUR.
EX121 DY020219 / 100 / 3.7 : 2.9, 21 GM 10922 , 21 SOME SNOW IN TREES
.END
There was new snow on most lines. All lakes and most rivers were frozen.
NNNN

SHEF Message Key
  Line No.       Flight line number
  Survey Date    Survey Date
  %SC            Visual estimate of percent snow cover over flight line made by pilots
  SWE(in)        SWE, in inches, made using the %SM(M) soil moisture estimate
  SWE(35%)       SWE, in inches, made using an assumed 35% soil moisture
  %SM(M)         Percent soil moisture used in SWE calculation
  Est type       Type of estimate for %SM(M):
        AM       Airborne soil moisture measurement
        AI       Interpolated from airborne measurements
        GM       Ground-based soil moisture measurement
        GI       Interpolated from ground measurements
        SE       Subjective estimate
  Fall date      Survey date for fall soil moisture survey
  %SM(F)         Percent soil moisture measured/estimated in the fall
Pilot Remarks    Pilot remarks for flight line.

Summaries of flight line locations (mid-points of each flight line) are presented in comma-separated value (.csv) format.

Geographic attributes are formatted as ESRI shapefiles (*.shp, *.shx and *.dbf) and layer files (*.lyr).

SWE and soil moisture parameters for groups of flight lines collected during the same day are in files named wYYMMDDa.atw where YY is year, MM is month, and DD is day.

The latitude, longitude and elevation of the mid-points of all 129 flight lines are available in the file named Flight_lines.csv.

Geographic attributes are in ArcView shape files named co_####.dbf, co_####.shp, and co_####.shx where #### represents either cities (cities), highways (hways), lakes (lk), major rivers (maj_rivers), minor_rivers (minor rivers), or flight lines (flines).

Terrain elevation data are in the ArcView layer file named elevations_west32.tif.lyr.

Flight lines were flown throughout Fraser, North Park, and Rabbit Ears MSAs, which are all within the CLPX Small Regional Study Area (SRSA - 41.0°N, 39.5°N; 105.0°E,107.5°E).

Flight lines are of variable length and variable direction. Mid-points of each flight line (latitude, longitude, and elevation) are available in the file Flight_lines.csv. The number of flight lines flown and the dates of data collection are:

BG1: 20–22 September 2001
BG2: 17 September 2002
IOP1: 19-23 February 2002
IOP3: 19-21 February 2003
IOP4: 25-31 March 2003

Spatial Coverage Maps

Overview Map

Fraser MSA flight lines

North Park MSA flight lines

Rabbit Ears MSA flight lines

This data set presents snow water equivalent (SWE) derived from gamma radiation measurements, and snow cover (extent) and soil moisture.

For each over-snow flight line collected during the IOPs, parameters are:

• Visual estimates of percent snow cover of flight line made by pilots (%SC)
• SWE (inches) – made using measured estimates of percent soil moisture from background surveys [SWE (in)]
• SWE (inches) – made using an assumed 35 percent soil moisture [SWE(35%)]
• Percent soil moisture used in SWE calculations [%SM(M)]