% AIR_SEA: Introduction to the AIR_SEA TOOLBOX
% AIR_SEA TOOLBOX (version 2.0: 8/9/99)
%
% 1) Introduction: Welcome to the AIR_SEA toolbox, a collection of MATLAB
% programs (m-files) which can be used to compute surface wind stress and
% heat flux components from buoy and shipboard atmospheric and near-surface
% oceanographic time series measurements. All m-files include a header
% which describes the mfile's function, input and output variables, and
% key references when important. They have been written for use with
% MATLAB 5.
%
% 2) Conventions: While not required for many m-files, it is generally
% assumed that the input time series of measured variables are hourly
% averaged column or row vectors and the other input variables are scalars,
% all expressed in MKS units. Two time conventions are used: a) decimal
% Julian yearday where 0000 UT Jan 1 equals 0.0, and b) calender yearday
% where Jan 1 equals 1. The choice of which convention is used is
% internally consistent between m-files.
%
% 3) Programs used to compute heat flux components:
%
% Shortwave flux:
%
% SWHF: computes net sw flux into ocean and albedo. Uses
% SORADNA1 and ALBEDO to compute solar altitude, no-sky
% insolation and albedo.
%
% SORADNA1: computes no-sky insolation and solar altitude at
% a given time and location.
%
% ALBEDO: computes ocean albedo following Payne (1972).
%
% Longwave flux:
%
% LWHF: computes net lw flux into ocean when downward
% lw radiation is measured, using Dickey et al (1994).
%
% BLWHF: computes net lw flux into the ocean when downward
% lw radiation is NOT measured. Uses SATVAP. Requires
% as input a cloudiness correction factor from CLOUDCOR.
%
% CLOUDCOR: cloudiness correction factor used in bulk formulae,
% based on estimated Cloud Fraction, which is either observed
% directly or estimated, using, e.g., REEDCF.
%
% REEDCF: computes daily average Cloud Fraction using formula of
% Reed (1977), who relates daily average cloudiness to the observed
% reduction in solar insolation from clear-sky values.
%
% Sensible and latent fluxes:
%
% HFBULKTC: uses a simplified version of Fairall et al (1996)
% TOGA/COARE code to compute sensible and latent heat
% fluxes into ocean. Present version includes a) Rogers'
% weighting factor for unstable conditions, b) the effects
% of gustiness, c) a constant marine boundary layer height,
% d) a limit of zr/L <=3.0 to ensure that the code converges
% to nonzero stress and heat flux values for strongly stable
% conditions, e) cool-skin effect, and f) Webb correction for
% latent heat flux. NOTE: both cool-skin and Webb correction
% are optional, and user must decide if they want these used,
% e.g., in SLHFTC. Warm layer effects are not included in this
% version. Uses VISCAIR and QSAT to compute air viscosity
% and saturation specific humidity, CDNTC the neutral drag
% coefficient, and PSIUTC and PSITTC to adjust the different
% transfer coefficients to the measurement heights for a
% given stability. Also returns related variables.
%
% SLHFTC: includes ocean surface current and HFBULKTC to comput
% sensible and latent heat fluxes into ocean.
%
% RAIN_FLUX: computes heat flux and momentum flux due to rain.
%
% 4) Programs relating wind speed, height, and surface stress.
%
% Neutral conditions:
%
% CDNLP: computes neutral Cd, 10m wind following Large and Pond (1981).
% CDNTC: computes neutral Cd, 10m wind following Smith (1988).
% CDNVE: computes neutral Cd, 10m wind following Vera (1983).
%
% STRESSLP: computes the neutral wind stress using Large and Pond.
% STRESSTC: computes the neutral wind stress following Smith.
% STRESSVE: computes the neutral wind stress using Vera.
%
% SPSHFTLP: computes winds at another height using Large&Pond drag.
% SPSHFTTC: computes winds at another height using Smith drag.
% SPSHFTVE: computes winds at another height using Vera drag.
%
% Non-neutral conditions:
%
% HFBULKTC: uses simplified version of Fairall et al (1996)
% TOGA/COARE code to compute surface wind stress amplitude,
% (Uses Monin-Obukov similarity theory with surface rougness using
% Charnock approach, like Smith (1988)).
%
% SLHFTC: includes ocean surface current and HFBULKTC to
% compute surface wind stress vector as well as scalar parameters.
%
% 5) Programs used to estimate wave effects on the measured wind speed:
%
% WAVEDIST: estimate true wind speed at 10-m height.
% WAVEDIS1: estimate true wind speed at measurement height.
% WAVEDIS2: plots wave effects at measurement height vs. wave height.
% OMEGALMC: estimates wave effect on wind log profile.
% CDNVE: computes neutral drag coefficient following Vera (1983).
%
% See WDNOTES for additional information.
%
% 6) Other useful programs:
%
% AS_CONSTS: contains various constants used in the toolbox.
%
% DAVEALB: computes daily mean albedo.
% SUNRISE: computes GMT time of sunrise and sunset (uses SORADNA1).
%
% GREG2: converts decimal yearday into Julian calendar day.
% JULIANMD: converts Gregorian calendar dates to decimal Julian day
% for days beginning at midnight UT
% YEARDAY: converts calender month and day into yearday.
%
% DELQ: air-sea specific humidity difference.
% EP: net precipitation and evaporation accumulation.
% QSAT: saturation specific humidity.
% RELHUMID: relative humidity from wet/dry bulb thermometers.
% RHADJ: adjusts RH for values above 100.
% SATVAP: saturation vapour pressure.
% VAPOR: heat of evaporation.
% VISCAIR: viscosity of air at a given temperature.
% COOL_SKIN: computes cool-skin parameters.
% T_HFBULKTC: tests HFBULKTC with COARE data.
%
% 7) See CONTENTS for listing of all m-files in this toolbox.
%
% 8) History:
%
% Version 1.0:
%
% The initial assembly of this toolbox was a collaborative effort
% by Bob Beardsley (WHOI), Ed Dever (SIO), Steve Lentz (WHOI), Jim
% Edson (WHOI), and Dick Payne (WHOI), with additional input from
% Steve Anderson (WHOI), Jay Austin (WHOI), Chris Fairall (NOAA),
% Carl Friehe (UCI), Bill Large (NCAR), Dave Rogers (SIO), Rich
% Signell (USGS), and Bob Weller (WHOI). Their input was very useful.
%
% Version 1.1:
%
% Rich Pawlowicz (UBC) then converted the original version 1.0
% (written for MATLAB 4) into a much improved version 1.1 (optimized
% for MATLAB 5) which included major coding improvements, the addition
% of some new m-files, and some corrections of existing m-files.
%
% Version 1.2:
%
% Ayal Anis (U. Dalhousie) then modified HFBULKTC to include the
% Fairall et al (1996) cool-skin effect and Webb correction to the
% latent heat flux, plus added files to test the code with COARE
% data. Ayal and R. Onken (NATO) also contributed several other files.
%
% Version 2.0:
%
% Bob Beardsley has added several m-files and made simple changes
% to the various m-files to standardize the format and documentation.
%
% 9) Comments, Suggestions, and Improvements
%
% Please contact Bob Beardsley at rbeardsley@whoi.edu with questions
% and comments, especially concerning bugs (and their possible fixes),
% ideas for additional m-files, plus any m-files which you want to
% contribute to this toolbox. Your help in improving this toolbox will
% be greatly appreciated.
%
% As new or/or improved m-files are developed for this toolbox, they
% will be added to the AIR_SEA toolbox folder located at the SEA-MAT
% Web site (crusty.usgs.gov/sea-mat/). SEA-MAT is a collection of
% MATLAB mfiles for the display and analysis of oceanographic data.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%