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Comparative Altitude Determination of Overshooting Tops in Severe Thunderstorms Rachel Goldberg* and Dr

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Comparative Altitude Determination of Overshooting Tops in Severe Thunderstorms Rachel Goldberg* and Dr A23D-0200 Comparative Altitude Determination of Overshooting Tops in Severe Thunderstorms Rachel Goldberg* and Dr. Nathan Magee The College of New Jersey Introduction Methods, Data, and Results Discussion & Future Work ⚡Our Goal: To determine and compare the cloud top heights of Methods Data and Results What We Found: deep convective clouds and overshooting tops using multiple ⚡We found that Bufkit has the greatest variability with radar methods. Overshooting tops form in cumulonimbus where strong close behind. This means that although radar and CloudSat updrafts penetrate the tropopause. Applications include ⚡Catalogued occurrences of deep convection from 1/1/11 to Our Data: are almost identical in regard to mean altitude, the cloud optimization of aviation rerouting decisions around severe 7/1/11 using data from: tops fluctuate more for radar than CloudSat. This is convection and improved forecasting of tornadogenesis. - CALIPSO 40 probably due to radar having elevation scans that have 35 Figure 4: Virginia, gaps in between. 30 4/9/11 ⚡ As expected, our data demonstrates that CALIPSO The light blue 25 detects cloud tops at higher altitude due to sensitivity to represents the 20 small particles on cloud edges. detected clouds 15 ⚡Modeling data often agrees well with other methods, but and the black 10 Cloud Top Height (kft) Height Top Cloud as can be seen by the high standard deviation, it is also represents 5 subject to completely incorrect forecasts. attenuated 0 signals. Therefore, Radar Bufkit CALIPSO CloudSat (124 samples) (118 samples) (119 samples) (62 samples) the black signifies thick clouds. Figure 9: The average of cloud top heights determined by four http://www- methods are listed in kilofeet. calipso.larc.nasa. gov/ Above we can see that radar and CloudSat have the closest - CloudSat mean height, while Bufkit and CALIPSO have the most different. CALIPSO has the highest mean height and the model output has the lowest. Figure 1: Above is a diagram of a cumulonimbus cloud that has an overshooting top. http://wx.db.erau.edu/faculty/ Number of Average Standard Correlation Samples Deviation Coefficient ⚡NASA Satellite Use: Radar - 122 2.1 12.0 0.510 Bufkit Radar - 119 9.9 10.2 0.396 CALIPSO Figure 5: Virginia 4/9/11 Figure 11: An overshooting top as seen by a passing plane. Radar - 62 6.4 4.6 0.696 In this case, the orange represents where the greatest reflectivity is. In http://pl.wikipedia.org/ CloudSat other words, the orange is where the largest water droplets are Bufkit - located. In the most intense cumulonimbus, the reflectivity is red. 113 9.2 9.4 0.383 The Implications: CALIPSO http://www.cloudsat.cira.colostate.edu/ For Aviation: Bufkit- 61 6.5 7.5 0.564 ⚡Continuing our research could benefit aviation safety and - Aqua MODIS CloudSat efficiency. Using our results, air traffic control could optimize CALIPSO 57 5.4 5.2 0.444 procedures for determining when a pilot should deviate - CloudSat from a flight path. Figure 6: Kentucky and Virginia, 4/9/11 ⚡Real-time aviation decisions often rely primarily on radar The portions that look Table 2: The averages and standard deviations of the absolute echo-tops, but we find that ~5 kft of convection is typically “fluffy” are overshooting value of the differences between all of the methods. The units found above that height. Figure 2: Diagram of the five current satellites in the A-Train, a tops. are still in terms of kilofeet. suite of polar-orbiting satellites at 690 km altitude. http://ge.ssec.wisc.edu/m For Tornadogenesis: http://earthobservatory.nasa.gov odis-today/\ The average difference between two methods is smallest for ⚡Researchers have linked a decrease in the heights of radar and Bufkit. The average that has the largest difference is overshooting tops, that typically appear several minutes The three satellites we used to compare cloud top heights were between the radar and CALIPSO. Radar and CALIPSO likely prior to a tornado touchdown, to tornadogenesis. CALIPSO, CloudSat, and Aqua. CALIPSO uses lidar, which is a have the largest difference because radar has gaps between ⚡ Our research can allow us to examine the instances in visible light based instrument that detects small particles at cloud elevation scans and can get through opaque clouds, while which overshooting tops preceded tornadoes and analyze boundaries. CloudSat uses radar, which is a radio wave based -North American Mesoscale - NEXRAD Radar CALIPSO is in space and can detect small particles in high their evolution with time and maximum altitude. It is possible instrument (94 GHz) that detects clouds containing larger modeling data altitude clouds. The correlation coefficients indicate that that this analysis could lead to insights into timing and particles. Aqua has an instrument MODIS that provides a between thirty-eight and seventy percent of the data can be intensity of tornadoes. Because tornadic cloud intercepts horizontal view of the clouds at 250 m resolution. explained by one another. by the A-Train are rare, this would require expanding our study to previous seasons. ⚡ Radar Use: Our Sighting: Figure 10: *Corresponding Author Address: New Jersey, Rachel Goldberg, [email protected] 7/16/11 Acknowledgements CALIPSO lidar We would like to thank NASA for funding our project. Funded by NASA grant #NNX11AI27G profile in Google Earth with MODIS Figure 7: North Carolina, 4/9/11 Figure 8: North Carolina, 4/9/11 References image Adler, R.F., D.D. Fenn, 1981: Satellite-Observed Cloud-Top Height Changes in Tornadic Thunderstorms. J. Appl. Figure 3: A VCP 21 radar that has 14 elevation scans with the Modeling data estimates the The light blue represents cloud Meteor., 20, 1369–1375. simultaneous with Bedka, A., et al, 2009: Objective Satellite-Based Detection of Overshooting Tops Using Infrared Window Channel greatest angle scan at 19.5 cloud top heights based on the tops of maximum 15 kft, dark blue Brightness Temperature Gradients, J. Appl. Meteor. Climatol., 49, 181-202 visual sighting of Chmielewski, V., et al, 2011: Assessing Impulses and Decay of Overshooting Tops Relative to Supercell Collapse degrees.http://www.srh.noaa.gov/jetstream temperature and dew point with of maximum 30 kft, and green using Lightning and Phased Array Radar Data, 91st American Meteorological Society Annual Meeting small cumulus. Kahn, B.H., et al, 2007: Cloud Type Comparisons of AIRS, CloudSat, and CALIPSO Cloud Height and Amount, Atmos. Chem. up to six hours lead time. The maximum 47 kft. The image was Direct sighting Phys., 8, 1231-1248 maximum here is 37 kft. The image generated by the NOAA Weather Maddox, R.A., et al, 1999: “Echo Height Measurements with the WSR-88D: Use of Data from One Versus Two Radars, Wea. By using simultaneous Doppler radar data, we were able to gave 3.06 km Forecasting, 20, 455-460 was generated by BUFKIT using and Climate toolkit using data Rhoda, D.A, et al, 2002, “Aircraft Encounters with Thunderstorms in Enroute vs. Terminal Airspace Above measure the maximum precipitation altitude of all satellite cloud top height; Memphis, Tennessee”, Tenth Conference on Aviation, Range, and Aerospace Meteorology, Portland, OR, data archived by Iowa State archived at the National Climatic Amer. Meteo. Soc. overpasses of deep convection. lidar data gave Stephens, G.L., et al, 2002: The CloudSat Mission and the A-Train: A New Dimension of Space-Based Observations of Clouds University. Data Center. and Precipitation, Amer. Meteor. Soc., 1771-1790 3.03 km height. Weisz, E., et al, 2007: Comparison of AIRS, MODIS, CloudSat and CALIPSO Cloud Top Height Retrievals, Geophys. Res. Lett., 34 .
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