% 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.

%

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