The following pages and posts are tagged with
| Title | Type | Excerpt |
|---|---|---|
| Geopotential Altitude | Page | Calculate altitude by integrating the hypsometric equation. |
| Ambient Point | Page | Determine the time where a dropsonde data series reaches ambient equilibration with the free atmosphere. |
| AVAPS RH Time Constant | Page | Calculate the AVAPS RS-80 relative humidity time constant. |
| AVAPS Tdry Time Constant | Page | Description Calculates time constants at each point through the entire profile for the temperature sensor on dropsondes using the pressure, temperature, and fall rate at that point. The fall rate used can be either the theoretical fall rate or the observed fall rate. Formula \(TC(pres,... |
| B-Spline | Page | Routine for fitting a b-spline, which provides smoothing and derivatives. |
| Buddy Check | Page | Description This test uses the data points on either side of an observation to check for consistency, and is useful for detecting and removing wild points. Since the neighboring points may be separated from the observation by varying time deltas, the thresholds for the buddy check are... |
| Create Surface Observation | Page | Extrapolate surface conditions based on last observation received. |
| Detrend | Page | Description Formula Source |
| Dropsonde Fall Rate | Page | Description Calculates the theoretical fall rate of a dropsonde at any point in the sounding. Formula Dropsonde fall rate \(v\) is calculated from pressure \(p\) (mb), temperature \(t\) (C), sonde mass \(m\) (g), parachute area \(a\) (cm2), and parachute coefficient of drag \(C_d\): \(v = \sqrt{\frac{2\times... |
| Dynamic Adjustment | Page | Description The temperature is adjusted for the time lag related to the sensor time constant. The time constant is a function of the sonde ascent rate and the density. An empirically determined relation for the sensor time constant, as a function of pressure and ascent rate, is... |
| Dynamic Wind Adjustment | Page | Description Adjust a wind component for the fall of a sonde (dropsonde only). The wind component series is first smoothed, and then a time tendency is computed for each data point. The observation is then adjusted according to the formula, using the previously calculated vertical velocity. <h2... |
| Fast fall check | Page | Description For each data point, the hydrostatically computed vertical velocity is compared to the theoretical fall rate. If the hydrostatic value is more than three times the theoretical value or the two values are of opposite sign, the point is discarded. If the hydrostatic value... |
| Filter Check | Page | Description A copy of the data series is low pass filtered at a given wavelength. Data points are removed if they differ from the filtered series by greater than a specified deviation. Source |
| GDL Significant Levels | Page | Description Algorithm for calculating additional levels between mandatory significant levels, so that the thermodynamic or winds profile can be reproduced from the minimum number of points. Levels are identified at points of greatest departure from linearity (GDL) throughout the sounding, recursively. Aspen includes user-settable thresholds for GDL... |
| Levels Calculation Overview | Page | Calculation Standard and significant levels for encoding in BUFR and TEMP messages are calculated in this order: Surface thermodynamic and winds Missing temperature Highest thermodynamic 110mb thermodynamic Inversions Station base pressure 110mb winds Highest wind Extrapolated altitudes for mandatory levels not covered by sounding GDL thermodynamic... |
| Limit Check | Page | Description Absolute bounds checks are used to discard measurements falling outside of hard limits. The limits are set at: Parameter Minimum Maximum P 1 mb 1200 mb T -100 °C 50 °C RH 0 % 120... |
| Offset | Page | Description Fixed offsets can be added to the pressure, temperature, and RH measurements. Algorithm Skip the first point if it is flight-level or surface data. Add the specified offset to all other values in the data series. Source Editsonde |
| Outlier | Page | Description A least-squares linear fit to the data series is calculated. Data points that are greater than a specified multiple of the standard deviation from the linear fit are removed from the data set. Source Editsonde |
| Position | Page | Description Aspen can either use the reported GPS position info from the sonde or integrate the poisiton using the horizontal winds. Aspen reports the observed position by default, but can be configured to integrate the sonde location from the initial launch position. If a time gap of... |
| Post-Splash Data Check | Page | Evaluate data at the end of the sounding for possible data transmitted after sonde hit surface. |
| Radiosonde RH Time Constant | Page | Description Formula Source |
| Radiosonde Tdry Time Constant | Page | Description Formula Source |
| Satellite Check | Page | Description GPS-derived winds may not be reliable if an insufficient number of satellites are used in their computation. If the number of satellites falls below the specified minimum, the associated wind observations are discarded. Source Editsonde |
| Scalar Adjustment | Page | Description If a surface pressure is specified on the main tab, it is proportionally applied to the pressure profile as a function of time. Thus the bottom pressure value becomes the specified pressure, and the launch pressure is unchanged, with a proportional adjustment applied between these points.... |
| Smooth | Page | Description Bspline smoothing is applied to pressure, temperature, RH, and winds series. The smoothing wavelength used in the Bspline for each series can be set with configuration parameters. Formula A Bspline curve is generated on the series using the given smoothing wavelength. Values in the... |
| Time Constant | Page | Description Formula Source |
| Time Dependent Tdry Bias Correction | Page | Description Formula Source |
| Trend | Page | Description Formula Source |
| Tropopause | Page | Description Formula Source |
| Vertical Velocity | Page | Description The pressure series is first smoothed using the final pressure-smoothing wavelength. The time tendency of the pressure is then computed at each data point. The time-differentiated hydrostatic equation is then used to compute the vertical velocity. This is done twice, the first time to be able... |
| Vertical Velocity Check | Page | Description The GPS-measured fall velocity is a good discriminator for the quality of the GPS-derived horizontal wind. This check compares the GPS vertical velocity with both the hydrostatically derived vertical velocity and the theoretical fall velocity. Differences are calculated at each point between the GPS... |
| Vertical Wind Speed | Page | Description Calculate a profile of the vertical wind speed (W), by taking the difference between the observed fall rate and the theoretical sonde fall rate. The theoretical rate is dependent upon the pressure and temperature. W is computed for points which have a dz value, and have... |
| Wind Error Check | Page | Description GPS-derived winds may not be reliable if the wind speed error value is too high. Acceptable values of wind speed error depend on the height of the sonde. The base threshold is acceptable for data between 10km and 100m in altitude. Above 10km the GPS must... |
| WL150 | Page | Calculate the mean wind in the lowest 150m layer of a dropsonde sounding. |
| Geopotential height encoding | Page | Description Geopotential height for standard levels is encoded in only 3 digits in TEMP messages. To enable this, height is recorded in decameters above the 700 hPa level and the thousands digit is left off, as it can be determined from the standard atmosphere. Formula ... |