Weather radar system and method for estimating vertically integrated liquid content
09612328 ยท 2017-04-04
Assignee
Inventors
Cpc classification
B64D45/00
PERFORMING OPERATIONS; TRANSPORTING
Y02A90/10
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
B64D43/00
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A hazard warning system includes a processing system. The processing system determines a vertically integrated liquid (VIL) parameter. The processing system receives radar reflectivity data associated with an aircraft radar antenna and determines the VIL parameter by determining a first reflectivity value at a first altitude and a second reflectivity value at a second altitude using the radar reflectivity data. The processing system determines the VIL parameter using a base storm altitude and a top storm altitude.
Claims
1. An aircraft hazard warning system, comprising: a processing system configured to determine a vertically integrated liquid (VIL) parameter, the processing system configured to receive radar reflectivity data associated with an aircraft radar antenna and determine the VIL parameter by determining a first reflectivity value at a first altitude and a second reflectivity value at a second altitude in response to the radar reflectivity data, the processing system being configured to determine if the VIL parameter is above a threshold and cause a display to provide a VIL region indicative of the VIL parameter being above the threshold, wherein the VIL region allows at least one weather region indicative of rainfall rates associated with the same location as the VIL region to be viewable.
2. The aircraft hazard warning system of claim 1, wherein a VIL warning is provided on an electronic display if the VIL parameter is above the threshold.
3. The aircraft hazard warning system of claim 1, wherein the VIL region is provided as a speckled region, a striped region, a bright region, a region with outlined contours, or a region with varying color saturation or brightness.
4. The aircraft hazard warning system of claim 1, wherein the first altitude is a freezing altitude.
5. The aircraft hazard warning system of claim 1, wherein the first and second reflectivity values are determined from a weather model based upon at least one reflectivity sample from the radar reflectivity data.
6. The aircraft hazard warning system of claim 1, wherein the processing system determines a predictive VIL parameter based upon historical VIL parameter data.
7. The aircraft hazard warning system of claim 1, wherein the VIL parameter is compared to a received VIL value from an off-aircraft source.
8. The aircraft hazard warning system of claim 1, wherein the VIL parameter is provided to a ground station or other aircraft.
9. The aircraft hazard warning system of claim 1, wherein the processing system is configured to determine the VIL parameter by using the first and second reflectivity values at two elevation angles.
10. An aircraft hazard warning system, comprising: a processing system for determining a vertically integrated liquid (VIL) parameter, the processing system configured to determine an altitude value based on received temperature data, wherein the processing system is configured to determine the VIL parameter based on the determined altitude value, wherein the processing system is configured to use the VIL parameter to detect lightning, a convective cell, turbulence, hail, or ice.
11. The aircraft hazard warning system of claim 10, wherein the processing system uses a different equation for the VIL parameter for tropical/continental, and tropical/oceanic, and mid-continent environments.
12. The aircraft hazard warning system of claim 10, wherein the VIL parameter is used in inferential weather detection.
13. The aircraft hazard warning system of claim 10, wherein the altitude value includes values indicative of: a base storm altitude, a top storm altitude, a freezing level altitude, and a predefined temperature level altitude.
14. The aircraft hazard warning system of claim 13, wherein the predefined temperature level altitude is 40 Celsius.
15. The aircraft hazard warning system of claim 10, wherein the temperature data includes at least one of a local atmospheric temperature value, a local temperature variation with time value, a local temperature variation with altitude value, and a remotely determined temperature value.
16. A method of determining a vertically integrated liquid (VIL) parameter on an aircraft using an electronic processor, the method comprising: receiving radar reflectivity data and determining a first reflectivity value at a first altitude and a second reflectivity value at a second altitude using the electronic processor; providing the VIL parameter in response to the first reflectivity value and the second reflectivity value; and storing a rate of change over time of the VIL parameter.
17. The method of claim 16, wherein the first altitude is a freezing level altitude and the second altitude is a predefined temperature altitude.
18. The method of claim 17, wherein the rate of change is used to predict a predicted VIL parameter.
19. The method of claim 16, further comprising performing additional vertical sweeps to obtain more accurate VIL parameters in a limited region or performing additional horizontal sweeps to improve interpolation.
20. The method of claim 16, further comprising determining the VIL parameter by using the first and second reflectivity values at two elevation angles.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Exemplary embodiments will become more fully understood from the following detailed description, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like elements, and:
(2)
(3)
(4)
(5)
(6)
(7)
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
(8) Before describing in detail the particular improved system and method, it should be observed that the invention includes, but is not limited to a novel structural combination of conventional data/signal processing components and communications circuits, and not in the particular detailed configurations thereof. Accordingly, the structure, methods, functions, control and arrangement of conventional components software, and circuits have, for the most part, been illustrated in the drawings by readily understandable block representations and schematic diagrams, in order not to obscure the disclosure with structural details which will be readily apparent to those skilled in the art, having the benefit of the description herein. Further, the invention is not limited to the particular embodiments depicted in the exemplary diagrams, but should be construed in accordance with the language in the claims.
(9) With reference to
(10) The current regulatory environment as defined by governmental regulatory agencies supports display of basic radar sensor information as red, yellow, and green for radar reflectivity calibrated to rainfall rate and magenta as turbulence. However, reflectivity measurements do not necessarily show the severity of weather. Applicants believe that the VIL content parameter may be a better indicator of a potential threat of a weather system (e.g., a cell, storm, etc.). Advantageously, weather system 10 detects VIL content using data available at the flight deck in one embodiment. An indication that does not interfere with the current regulatory environment, such as a speckled region (e.g., red, yellow, etc.), can be displayed as a VIL warning or hazard area on one or more of displays 18 in one embodiment.
(11) The regulatory agencies do not currently provide guidance for changing the definition of the radar display based on VIL content hazards, although there is an FAA precedent for replacing reflectivity-based hazard colors with VIL-based colors. For example, the Corridor Integrated Weather System maps reflectivity and VIL to a common hazard scale. See, Robinson, M., Evans, J. E., Crowe, B. A., En Route Weather Depiction Benefits of the NEXRAD Vertically Integrated Liquid Water Product Utilized by the Corridor Integrated Weather System, 10th Conference on Aviation, Range, and Aerospace Meteorology (ARAM), Portland, Oreg., Amer. Meteor. Soc., 2002. The radar display format may be selected to display radar colors consistent with or complementary to turbulence and rainfall rate as currently defined by regulatory authorities or as defined in the future by such authorities in one embodiment. A hazard assessment indication based on VIL content parameters can be provided in a manner that does not interfere with display of standard weather data in one embodiment.
(12) Referring to
(13) Radio 23 can receive parameters or data from sources outside of the aircraft. For example, NEXRAD data can be received by radio 23 and used by processor 14 for hazard detection. In addition, VIL content, temperature (e.g., temperature at various altitudes) and altitude can be received via radio 23 from the National Weather Service (NWS) or other source. Displays 18 can be head up displays (HUDs), head down displays (HDD), primary flight displays, weather radar displays, etc.
(14) Processor 14 is generally configured to process data received from sensor inputs 12 to determine a hazard threat level, receive input from user input 16, and provide at least one hazard indication on display 18. Processor 14 includes a VIL detector 28 in one embodiment. Processor 14 can generate a velocity parameter 32 or other Doppler data, a spectral width parameter 34, a reflectivity parameter 36, and a range parameter 38 based on return data from sensor inputs 12, data or commands from user input 16, or data or instructions from memory 20. Although Doppler data, the velocity parameter, and the spectral width parameter are mentioned above, detector 28 does not require Doppler data and spectral width data to determine the VIL parameter. Memory 20 can include a database of weather models. The weather models can include reflectivity profiles with respect to altitudes referenced to temperature for particular, times of years, times of day, locations, types of storm cells. According to various exemplary embodiments, processor 14 can be any hardware and/or software processor or processing architecture capable of executing instructions and operating on data related to hazard detection. According to various exemplary embodiments, memory 20 can be any volatile or non-volatile memory capable of storing data and/or instructions related to hazard warning system 10.
(15) VIL detector 28 is configured to provide a VIL content parameter and/or a VIL warning in one embodiment. In one embodiment, VIL detector 28 uses vertical sweeps on weather cells to assess the VIL content parameter. VIL detector 28 can use the combination of reflectivity at altitudes associated with certain temperatures to determine the VIL content parameter in one embodiment. The reflectivity at altitudes associated with certain temperatures can be directly sampled via antenna 22 in one embodiment or can be derived using two or more sensed reflectivity values and a stored weather model in memory 20 in another embodiment. Processor 14 can access memory 20 and select a particular reflectivity profile in a weather model stored in memory 20 by comparing sampled reflectivity levels at altitudes sensed via antenna 22 to the reflectivity profiles associated with the weather model. The processor 14 selects reflectivity values at particular altitudes from the selected particular weather profile to calculate the VIL parameter in one embodiment.
(16) Temperature data can be provided by temperature sensor 26, input 16, or radio 23 and can include a local atmospheric temperature, local temperature variations with time, local temperature variations with altitude, a remotely determined temperature, and/or remotely determined temperature gradients in either range or altitude. The altitude associated with such temperature can be calculated or received by system 10. In one embodiment, a temperature available from the NWS twice a day is used. Detector 28 can receive data inputs derived from one or more of spectral width parameter 34, reflectivity parameter 36, and/or range parameter 38 to assess and locate convective cells. Detector 28 can receive a convective cell location and storm top height and base height (sometimes referred to as ceiling height) determined from detection algorithms used by processor 14. For example, processor 15 can use a routine for identifying storm tops and convective cells by analyzing lightning data, reflectivity data, spectral parameters, etc. In one embodiment, storm top altitude and storm base or ceiling altitude can be received from NWS by radio 23.
(17) Advantageously, VIL detector 28 can utilize existing sensors associated with sensor inputs 12 aboard aircraft 11 to obtain a VIL content estimate or parameter. In one embodiment, airborne radar sweeps are made in less than 10 seconds to obtain reflectivity measurements or radar return data at two or more altitudes. In one embodiment, three or more vertical samples are taken.
(18) The reflectivity measurements are used to calculate the VIL content parameter via an equation or algorithm in one embodiment. The VIL content parameter can be estimated several times per minute if warranted by weather condition. In one embodiment, the VIL parameter can be based upon a weather model for a particular region, a particular time of year, and/or a particular time of day. The weather model can contain reflectivity levels with respect to atmospheric temperatures. Interpolation and extrapolation can be used to determine reflectivity levels at unobserved points to fill the vertical column of reflectivity levels. In one embodiment, these reflectivity values are compared to a weather model stored in memory 20. System 10 performs a best fit match to the weather models or curves to complete a reflectivity profile from the surface of the earth to an altitude. Reflectivity points between the surface of the earth and the altitude can be taken from the reflectivity model for the VIL calculation. For example, system 10 can advantageously be used in an aircraft 11 flying at 12,000 feet. A first scan provided at 12,000 feet can be performed and a second scan directed to a point at 25,000 feet can be performed. With reflectivity values at these two points, a reflectivity profile associated with the model can be chosen based upon location, time of day, time of year and the sampled reflectivity points. In one embodiment, the weather models may be associated with different types of air masses or different types of cell types in that region. For example, a model may be available for a squall line type cell or a stratus or stratiform cell in a particular region.
(19) In one embodiment, VIL content detector 28 operates according to an algorithm. According to one embodiment, the algorithm is based upon the following values: A.sub.Freezing= The altitude of the freezing level; A.sub.40= The altitude of the 40 C. level; A.sub.Base= The altitude of the storm base (potentially available from a NEXRAD system. This value may be set to the reported or estimated ceiling in the vicinity of the storm in one embodiment); A.sub.Top= The altitude of the storm top (potentially available from the NEXRAD system. In the absence of measured data, this value could be set to the tropopause height in one embodiment); R.sub.Freezing= The radar reflectivity in dBZ at the freezing level; R.sub.40= The radar reflectivity in dBZ at the level 40 C. level; M.sub.Freezing= The rain mass per unit volume at the freezing level; M.sub.40= The rain mass per unit volume at the 40 C. level; and M*= The rain mass per unit area, i.e., the vertically integrated liquid water value.
(20) The R.sub.Freezing and R.sub.40 values can be determined from the appropriate weather model (location, time of year, weather type, time of day, etc.) and reflectivity measurements via radar antenna 22 or can be sampled via radar antenna 22.
(21) VIL detector 28 can calculate M* according to one embodiment using one of the two following equations:
(22)
(23)
(24) If any of the four altitude values are unknown, estimations based on the location and ambient conditions can be made in one embodiment. Applying this algorithm to sample data from the Zipser and Lutz vertical reflectivity v. altitude data (the mid-continent (MC) median curve of
(25) In one embodiment, a special case can arise if A.sub.Top<A.sub.40 (i.e., the top of the storm cell does not rise to the 40 C. altitude). In this case, if system 10 has sufficient access to radar, a new scan can be made at a lower altitude, (e.g., the 30 C. level, 20 C. level, 10 C. level, etc.) and the altitude and reflectivity values in the formula adjusted accordingly. The adjustment to Equation 1 and 2 can be made by substituting A.sub.newvalue for A.sub.40 and M.sub.newvalue for M.sub.40 in one embodiment. If it is not feasible to execute a new scan, M.sub.40 may be set to 0 with A.sub.40 set to the altitude of the failed scan or to A.sub.40. Applicants believe that this process may underestimate the VIL content value, but this underestimation may not be significant if the storm top is at a low altitude.
(26) The same approach associated with Equations 1 and 2 can be applied over land in tropical regions as well as temperate regions in certain embodiments. Oceanic storm systems can behave somewhat differently, with the reflectivity values dropping rapidly above the freezing level. Equation 1 can be modified with respect to the transition region. In one embodiment, the more rapid drop in reflectivity with altitude is accommodated by using equation 2 above. The arithmetic mean of M.sub.Freezing and M.sub.40 in equation 1 is replaced with geometric mean of the same two values in equation 2.
(27) Applying this algorithm to the tropical oceanic curve of sample data from the Zipser and Lutz reflectivity v. altitude data results in an estimated VIL content of 0.002750, 7.61% lower than the 0.002976 value calculated using the actual reflectivity at each sample. Applicants believe that this amount of error may not be significant because oceanic storms are most commonly stratiform and consequently of less danger to aviation.
(28) In the tropical oceanic curve, the case of zero reflectivity at the 40 C. level can be addressed by performing a scan at a lower level that does have measurable reflectivity. If this approach is not taken, substitution of zero for M.sub.40 can be used, but applicants believe that this may be unsatisfactory in certain situations as this would set both of the last two terms of equation 2 to zero. In one embodiment, M.sub.40 is set to a small value, 2 or 3 orders of magnitude less than M.sub.Freezing.
(29) The advantage of this method is that new VIL content values may be obtained in the amount of time needed to scan the area in front of aircraft 11 a small number of times (2 to 3), typically 10 to 15 seconds in one embodiment. With aircraft 11 moving at 10 nautical miles per minute, an airborne VIL content estimate computed every 10 to 30 seconds gives the flight crew the opportunity to react in a timely manner to hazards in the range of 20 to 30 nautical miles in front of the aircraft. Using the ground based NWS, VIL content estimates that are 5 to 15 minutes old, which limits the crew to knowledge of hazards that may be only a few nautical miles away by the time they receive the alert. In this way, use of the airborne VIL content estimate can enhance flight safety and reduce passenger discomfort due to air turbulence in weather hazard regions.
(30) With reference to
(31) Various weather radar procedures can be utilized to determine storm tops and storm bases (ceilings). Alternatively, A.sub.Base and A.sub.Top values can be provided from information sources external to aircraft 11 such as a NEXRAD system. Similarly, A.sub.Freezing value and A.sub.40 values can be determined from the weather radar system or a source external to aircraft 11. Such values can be received before or during flight.
(32) At a step 220, detector 28 of processor 14 causes a radar scan to be performed to determine a reflectivity value R.sub.Freezing at an altitude of A.sub.Freezing and a reflectivity value at an altitude A.sub.40. Alternatively, the R.sub.Freezing value and R.sub.40 value can be determined from a weather model using two reflectivity values at two vertical locations along an azimuth scan. Alternatively, processor 14 can use data from scans already performed and use that data to determine the R.sub.Freezing and R.sub.40 values at a step 240 in one embodiment. In one embodiment, processor 14 uses a weather radar hazard scan that includes an azimuth scan at a tilt angle associated with A.sub.Freezing and a tilt angle associated with A.sub.40.
(33) At a step 230, processor 14 determines an MFreezing value, an M40 value, and an M* value (the VIL content parameter) from the MFreezing value, the M40 value (e.g., using Equations 1 or 2 in one embodiment). In one embodiment, the M40 value and MFreezing value are determined using the following equation.
M.sub.Freezing=3.4410.sup.6(10.sup.R.sup.
M.sub.40=3.4410.sup.6(10.sup.R.sup.
(34) At a step 240, a hazard warning can be provided on display 18 if the VIL content parameter is above a threshold. Alternatively, processor 14 can use a VIL content value in various other detection algorithms utilized by system 10.
(35) With reference to
(36) With reference to
(37) With reference to
(38) In some embodiments, system 10 (e.g., the radar or avionics equipment) may receive uplink or off-aircraft information regarding detected and/or forecast regions with VIL potential. System 10 may be used to qualify or confirm the assessment by adjusting radar parameters when scanning the detected regions (e.g., gain, etc.), increasing the dwell time in those regions, performing additional scans in those regions, etc. For example, an additional vertical sweep or sweeps can be performed in a limited region to get more accurate VIL information in the limited region. In another example, an additional horizontal sweep or sweeps can be performed in a limited region to improve interpolation. The off-aircraft assessment may be used to increase the confidence in the VIL assessment and be used to display a VIL hazard warning in that region. In some embodiments, the uplink or remote information (e.g., from ground, other aircraft, satellite, etc.) may include an observation or forecast of one or more of weather information of interest, including icing potential, convective level, size, maturity, reflectivity, winds, temperature, etc. The VIL threat assessment and information originating on aircraft 11 for the VIL assessment may also be down linked or sent to a ground station or off-aircraft system, so that the off-aircraft system can aggregate multiple aircraft observations for the development of a global VIL map or global VIL forecast that can then be uplinked to other aircraft in the vicinity or using the airspace in the future.
(39) Processor 14 can store historical trends of the VIL parameter in one embodiment. Processor 14 can provide a predictive VIL parameter based upon the historical trends in one embodiment. Processor 14 can track a rate of change over time and use a linear prediction of the VIL parameter based upon time, the rate of change and a historical value in one embodiment. Processor 14 can provide an inferred threat based upon the predictive VIL parameter and display such a predictive threat. The predictive threat can be determined when the predictive VIL parameter is above a threshold. In one embodiment, at least some of the values for the historical trends of the VIL parameter can be provided by off aircraft sources, such as, the NWS or other aircraft.
(40) According to various exemplary embodiments, methods 200, 300 and 400 of
(41) While the detailed drawings, specific examples, detailed algorithms and particular configurations given describe preferred and exemplary embodiments, they serve the purpose of illustration only. The inventions disclosed are not limited to the specific forms and equations shown. For example, the methods may be performed in any of a variety of sequence of steps or according to any of a variety of mathematical formulas. The hardware and software configurations shown and described may differ depending on the chosen performance characteristics and physical characteristics of the weather radar and processing devices. For example, the type of system components and their interconnections may differ. The systems and methods depicted and described are not limited to the precise details and conditions disclosed. The flow charts show preferred exemplary operations only. The specific data types and operations are shown in a non-limiting fashion. Furthermore, other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the invention as expressed in the appended claims.
(42) Some embodiments within the scope of the present disclosure may include program products comprising machine-readable storage media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable storage media can be any available media which can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable storage media can include RAM, ROM, EPROM, EEPROM, CD ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable storage media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machine to perform a certain function or group of functions. Machine or computer-readable storage media, as referenced herein, do not include transitory media (i.e., signals in space).