AIR_SEA: Introduction to the AIR_SEA TOOLBOX

0001 % AIR_SEA: Introduction to the AIR_SEA TOOLBOX 0002 0003 % AIR_SEA TOOLBOX (version 2.0: 8/9/99) 0004 % 0005 % 1) Introduction: Welcome to the AIR_SEA toolbox, a collection of MATLAB 0006 % programs (m-files) which can be used to compute surface wind stress and 0007 % heat flux components from buoy and shipboard atmospheric and near-surface 0008 % oceanographic time series measurements. All m-files include a header 0009 % which describes the mfile's function, input and output variables, and 0010 % key references when important. They have been written for use with 0011 % MATLAB 5. 0012 % 0013 % 2) Conventions: While not required for many m-files, it is generally 0014 % assumed that the input time series of measured variables are hourly 0015 % averaged column or row vectors and the other input variables are scalars, 0016 % all expressed in MKS units. Two time conventions are used: a) decimal 0017 % Julian yearday where 0000 UT Jan 1 equals 0.0, and b) calender yearday 0018 % where Jan 1 equals 1. The choice of which convention is used is 0019 % internally consistent between m-files. 0020 % 0021 % 3) Programs used to compute heat flux components: 0022 % 0023 % Shortwave flux: 0024 % 0025 % SWHF: computes net sw flux into ocean and albedo. Uses 0026 % SORADNA1 and ALBEDO to compute solar altitude, no-sky 0027 % insolation and albedo. 0028 % 0029 % SORADNA1: computes no-sky insolation and solar altitude at 0030 % a given time and location. 0031 % 0032 % ALBEDO: computes ocean albedo following Payne (1972). 0033 % 0034 % Longwave flux: 0035 % 0036 % LWHF: computes net lw flux into ocean when downward 0037 % lw radiation is measured, using Dickey et al (1994). 0038 % 0039 % BLWHF: computes net lw flux into the ocean when downward 0040 % lw radiation is NOT measured. Uses SATVAP. Requires 0041 % as input a cloudiness correction factor from CLOUDCOR. 0042 % 0043 % CLOUDCOR: cloudiness correction factor used in bulk formulae, 0044 % based on estimated Cloud Fraction, which is either observed 0045 % directly or estimated, using, e.g., REEDCF. 0046 % 0047 % REEDCF: computes daily average Cloud Fraction using formula of 0048 % Reed (1977), who relates daily average cloudiness to the observed 0049 % reduction in solar insolation from clear-sky values. 0050 % 0051 % Sensible and latent fluxes: 0052 % 0053 % HFBULKTC: uses a simplified version of Fairall et al (1996) 0054 % TOGA/COARE code to compute sensible and latent heat 0055 % fluxes into ocean. Present version includes a) Rogers' 0056 % weighting factor for unstable conditions, b) the effects 0057 % of gustiness, c) a constant marine boundary layer height, 0058 % d) a limit of zr/L <=3.0 to ensure that the code converges 0059 % to nonzero stress and heat flux values for strongly stable 0060 % conditions, e) cool-skin effect, and f) Webb correction for 0061 % latent heat flux. NOTE: both cool-skin and Webb correction 0062 % are optional, and user must decide if they want these used, 0063 % e.g., in SLHFTC. Warm layer effects are not included in this 0064 % version. Uses VISCAIR and QSAT to compute air viscosity 0065 % and saturation specific humidity, CDNTC the neutral drag 0066 % coefficient, and PSIUTC and PSITTC to adjust the different 0067 % transfer coefficients to the measurement heights for a 0068 % given stability. Also returns related variables. 0069 % 0070 % SLHFTC: includes ocean surface current and HFBULKTC to comput 0071 % sensible and latent heat fluxes into ocean. 0072 % 0073 % RAIN_FLUX: computes heat flux and momentum flux due to rain. 0074 % 0075 % 4) Programs relating wind speed, height, and surface stress. 0076 % 0077 % Neutral conditions: 0078 % 0079 % CDNLP: computes neutral Cd, 10m wind following Large and Pond (1981). 0080 % CDNTC: computes neutral Cd, 10m wind following Smith (1988). 0081 % CDNVE: computes neutral Cd, 10m wind following Vera (1983). 0082 % 0083 % STRESSLP: computes the neutral wind stress using Large and Pond. 0084 % STRESSTC: computes the neutral wind stress following Smith. 0085 % STRESSVE: computes the neutral wind stress using Vera. 0086 % 0087 % SPSHFTLP: computes winds at another height using Large&Pond drag. 0088 % SPSHFTTC: computes winds at another height using Smith drag. 0089 % SPSHFTVE: computes winds at another height using Vera drag. 0090 % 0091 % Non-neutral conditions: 0092 % 0093 % HFBULKTC: uses simplified version of Fairall et al (1996) 0094 % TOGA/COARE code to compute surface wind stress amplitude, 0095 % (Uses Monin-Obukov similarity theory with surface rougness using 0096 % Charnock approach, like Smith (1988)). 0097 % 0098 % SLHFTC: includes ocean surface current and HFBULKTC to 0099 % compute surface wind stress vector as well as scalar parameters. 0100 % 0101 % 5) Programs used to estimate wave effects on the measured wind speed: 0102 % 0103 % WAVEDIST: estimate true wind speed at 10-m height. 0104 % WAVEDIS1: estimate true wind speed at measurement height. 0105 % WAVEDIS2: plots wave effects at measurement height vs. wave height. 0106 % OMEGALMC: estimates wave effect on wind log profile. 0107 % CDNVE: computes neutral drag coefficient following Vera (1983). 0108 % 0109 % See WDNOTES for additional information. 0110 % 0111 % 6) Other useful programs: 0112 % 0113 % AS_CONSTS: contains various constants used in the toolbox. 0114 % 0115 % DAVEALB: computes daily mean albedo. 0116 % SUNRISE: computes GMT time of sunrise and sunset (uses SORADNA1). 0117 % 0118 % GREG2: converts decimal yearday into Julian calendar day. 0119 % JULIANMD: converts Gregorian calendar dates to decimal Julian day 0120 % for days beginning at midnight UT 0121 % YEARDAY: converts calender month and day into yearday. 0122 % 0123 % DELQ: air-sea specific humidity difference. 0124 % EP: net precipitation and evaporation accumulation. 0125 % QSAT: saturation specific humidity. 0126 % RELHUMID: relative humidity from wet/dry bulb thermometers. 0127 % RHADJ: adjusts RH for values above 100. 0128 % SATVAP: saturation vapour pressure. 0129 % VAPOR: heat of evaporation. 0130 % VISCAIR: viscosity of air at a given temperature. 0131 % COOL_SKIN: computes cool-skin parameters. 0132 % T_HFBULKTC: tests HFBULKTC with COARE data. 0133 % 0134 % 7) See CONTENTS for listing of all m-files in this toolbox. 0135 % 0136 % 8) History: 0137 % 0138 % Version 1.0: 0139 % 0140 % The initial assembly of this toolbox was a collaborative effort 0141 % by Bob Beardsley (WHOI), Ed Dever (SIO), Steve Lentz (WHOI), Jim 0142 % Edson (WHOI), and Dick Payne (WHOI), with additional input from 0143 % Steve Anderson (WHOI), Jay Austin (WHOI), Chris Fairall (NOAA), 0144 % Carl Friehe (UCI), Bill Large (NCAR), Dave Rogers (SIO), Rich 0145 % Signell (USGS), and Bob Weller (WHOI). Their input was very useful. 0146 % 0147 % Version 1.1: 0148 % 0149 % Rich Pawlowicz (UBC) then converted the original version 1.0 0150 % (written for MATLAB 4) into a much improved version 1.1 (optimized 0151 % for MATLAB 5) which included major coding improvements, the addition 0152 % of some new m-files, and some corrections of existing m-files. 0153 % 0154 % Version 1.2: 0155 % 0156 % Ayal Anis (U. Dalhousie) then modified HFBULKTC to include the 0157 % Fairall et al (1996) cool-skin effect and Webb correction to the 0158 % latent heat flux, plus added files to test the code with COARE 0159 % data. Ayal and R. Onken (NATO) also contributed several other files. 0160 % 0161 % Version 2.0: 0162 % 0163 % Bob Beardsley has added several m-files and made simple changes 0164 % to the various m-files to standardize the format and documentation. 0165 % 0166 % 9) Comments, Suggestions, and Improvements 0167 % 0168 % Please contact Bob Beardsley at rbeardsley@whoi.edu with questions 0169 % and comments, especially concerning bugs (and their possible fixes), 0170 % ideas for additional m-files, plus any m-files which you want to 0171 % contribute to this toolbox. Your help in improving this toolbox will 0172 % be greatly appreciated. 0173 % 0174 % As new or/or improved m-files are developed for this toolbox, they 0175 % will be added to the AIR_SEA toolbox folder located at the SEA-MAT 0176 % Web site (crusty.usgs.gov/sea-mat/). SEA-MAT is a collection of 0177 % MATLAB mfiles for the display and analysis of oceanographic data. 0178 % 0179 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0180

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