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ozonesonde ozone partial pressure calc #237

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LukePrior merged 1 commit into from
Feb 5, 2022
Merged

ozonesonde ozone partial pressure calc #237

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85 changes: 47 additions & 38 deletions js/xdata.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,43 @@
* Authors: Mark Jessop & Luke Prior
*/

function parseOzonesonde(xdata) {
// Pump Efficiency Correction Parameters for ECC-6A Ozone Sensor, with 3.0cm^3 volume.
// We are using these as a nominal correction value for pump efficiency vs pressure
//
OIF411_Cef_Pressure = [ 0, 2, 3, 5, 10, 20, 30, 50, 100, 200, 300, 500, 1000, 1100];
OIF411_Cef = [ 1.171, 1.171, 1.131, 1.092, 1.055, 1.032, 1.022, 1.015, 1.011, 1.008, 1.006, 1.004, 1, 1];

function lerp(x, y, a){
// Helper function for linear interpolation between two points
return x * (1 - a) + y * a
}

function get_oif411_Cef(pressure){
// Get the Pump efficiency correction value for a given pressure.

// Off-scale use bottom-end value
if (pressure <= OIF411_Cef_Pressure[0]){
return OIF411_Cef[0];
}

// Off-scale top, use top-end value
if (pressure >= OIF411_Cef_Pressure[OIF411_Cef_Pressure.length-1]){
return OIF411_Cef[OIF411_Cef.length-1];
}


// Within the correction range, perform linear interpolation.
for(i= 1; i<OIF411_Cef_Pressure.length; i++){
if (pressure < OIF411_Cef_Pressure[i]) {
return lerp(OIF411_Cef[i-1], OIF411_Cef[i], ( (pressure-OIF411_Cef_Pressure[i-1]) / (OIF411_Cef_Pressure[i]-OIF411_Cef_Pressure[i-1])) );
}
}

// Otherwise, bomb out and return 1.0
return 1.0;
}

function parseOzonesonde(xdata, pressure) {
// Attempt to parse an XDATA string from an ECC Ozonesonde
// Returns an object with parameters to be added to the sondes telemetry.
//
Expand All @@ -29,7 +65,7 @@ function parseOzonesonde(xdata) {
_output['ozonesonde_instrument_number'] = parseInt(xdata.substr(2,2),16);

// Cell Current
_cell_current = parseInt(xdata.substr(4,4),16)*0.001; // micro-Amps
_cell_current = parseInt(xdata.substr(4,4),16)*0.001; // uA
_output['ozonesonde_cell_current'] = Math.round(_cell_current * 1000) / 1000; // 3 DP

// Pump Temperature
Expand All @@ -48,44 +84,17 @@ function parseOzonesonde(xdata) {
_battery_voltage = parseInt(xdata.substr(14,2),16)*0.1; // Volts
_output['ozondesonde_battery_voltage'] = Math.round(_battery_voltage * 10) / 10; // 1 DP

return _output
}

// Pump Efficiency Correction Parameters for ECC-6A Ozone Sensor, with 3.0cm^3 volume.
// We are using these as a nominal correction value for pump efficiency vs pressure
//
OIF411_Cef_Pressure = [ 0, 2, 3, 5, 10, 20, 30, 50, 100, 200, 300, 500, 1000, 1100];
OIF411_Cef = [ 1.171, 1.171, 1.131, 1.092, 1.055, 1.032, 1.022, 1.015, 1.011, 1.008, 1.006, 1.004, 1, 1];

function lerp(x, y, a){
// Helper function for linear interpolation between two points
return x * (1 - a) + y * a
}

// Now attempt to calculate the O3 partial pressure (copy OIF411 calculations)

function get_oif411_Cef(pressure){
// Get the Pump efficiency correction value for a given pressure.

// Off-scale use bottom-end value
if (pressure <= OIF411_Cef_Pressure[0]){
return OIF411_Cef[0];
}

// Off-scale top, use top-end value
if (pressure >= OIF411_Cef_Pressure[OIF411_Cef_Pressure.length-1]){
return OIF411_Cef[OIF411_Cef.length-1];
}

// Calibration values
Ibg = 0.0; // The BOM appear to use a Ozone background current value of 0 uA
Cef = get_oif411_Cef(pressure); // Calculate the pump efficiency correction.
FlowRate = 28.5; // Use a 'nominal' value for Flow Rate (seconds per 100mL).

// Within the correction range, perform linear interpolation.
for(i= 1; i<OIF411_Cef_Pressure.length; i++){
if (pressure < OIF411_Cef_Pressure[i]) {
return lerp(OIF411_Cef[i-1], OIF411_Cef[i], ( (pressure-OIF411_Cef_Pressure[i-1]) / (OIF411_Cef_Pressure[i]-OIF411_Cef_Pressure[i-1])) );
}
}
_O3_partial_pressure = (4.30851e-4)*(_output['ozonesonde_cell_current'] - Ibg)*(_output['ozonesonde_pump_temperature']+273.15)*FlowRate*Cef; // mPa
_output['ozondesonde_O3_partial_pressure'] = Math.round(_O3_partial_pressure * 1000) / 1000; // 3 DP

// Otherwise, bomb out and return 1.0
return 1.0;
return _output
}

function parseOIF411(xdata, pressure){
Expand Down Expand Up @@ -615,7 +624,7 @@ function parseXDATA(data, pressure, temperature){
if (_instrument === '01') {
if (_current_xdata.length = 16) {
// Ozonesonde
_xdata_temp = parseOzonesonde(_current_xdata);
_xdata_temp = parseOzonesonde(_current_xdata, pressure);
_output = Object.assign(_output,_xdata_temp);
if (!_instruments.includes("Ozonesonde")) _instruments.push('Ozonesonde');
}
Expand Down