Tropical cyclone cloud‐top height and vertical temperature structure detection using GPS radio occultation measurements

Abstract

[1] The accurate determination of tropical cyclone (TC) cloud-top height and its vertical thermal structure using the GPS radio occultation (RO) technique is demonstrated in this study. Cloud-top heights are determined by using the bending angle anomaly and the temperature anomaly profiles during the TC events, and the results are compared to near-coincident cloud-top heights determined by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements. Based on 34 closely located RO-CALIOP pairs during 2006 to 2009, TC cloud-top heights from RO are highly correlated with CALIOP (r = 0.84), with a mean RO-CALIOP cloud-top height difference of approximately 500 m and a root-mean-square difference near 1 km. GPS RO data also allow analysis of the TC thermal structure, showing warm anomalies in the middle troposphere and cold anomalies in the upper levels, with a strong inversion near cloud top. We further investigate the thermal structure of the TCs from collocated radiosondes, and identify 246 RO-radiosonde pairs from 2001 to 2009. Radiosonde data confirm the thermal structure identified in GPS RO, with a strong inversion near the inferred cloud top. The mean difference between RO-derived inversion heights and those from radiosonde temperature profiles is approximately 500 m. Results show that, while cloud-top height detected from nadir-viewing satellites can be easily biased by a few kilometers, the biases of RO-derived cloud-top height are within~500 m.Citation: Biondi, R., S.-P. Ho, W. Randel, S. Syndergaard, and T. Neubert (2013), Tropical cyclone cloud-top height and vertical temperature structure detection using GPS radio occultation measurements,

Effect of tropical cyclones on the tropical tropopause parameters observed using COSMIC GPS RO data

“…These multiple tropopauses are similar to double tropopauses observed by Corti et al (2008), Biondi et al (2011), andDavis et al (2014). The cause for these multiple tropopauses might be either due to clouds (Biondi et al, 2013), wave activity, cirrus deck or ozone (Mehta et al, 2011), which demands separate investigation. We also calculated the tropopause parameters with respect to 100, 200, 300, 400, and 500 km distance away from the TC centre, respectively.…”

“…Here we considered a ±1 h time window of co-located RO profiles with respect to IMD cyclone best track data for obtaining the thermal structure over the TC period. Note that this is a better time window resolution than the earlier reported 3 h time window by Biondi et al (2013) for describing the thermal structure during the cyclone period. In general, no significant difference is evident in the temperature structure within 500 km from the TC centre below 14 km.…”

“…However, the availability of Global Positioning System (GPS) radio occultation (RO) measurements with high vertical resolution, high accuracy and all-weather capability has made it possible to study the tropopause characteristics over the globe including over oceans. Several studies showed that the GPS RO measurements are well suited for studying severe storms (Pommereau and Held, 2007;Corti et al, 2008;Romps and Kuang, 2009;Biondi et al, 2013).…”

“…Studies include the thermal and dynamical structure of UTLS during TC (Koteswaram, 1967), horizontal and vertical structure of temperature in the cyclone (Waco, 1970), temperature and ozone variations in a hurricane (Penn, 1965), troposphere-stratosphere transport and dehydration in cyclones (Danielsen, 1993), UTLS structure during TCs using AIRS and MLS measurements (Ray and Rosenlof, 2007), RO bending angle anomalies during tropical cyclones (Biondi et al, 2011), thermal structure of intense convective clouds derived from GPS RO (Biondi et al, 2012), estimating the TC cloud top height and vertical temperature structure using GPS RO measurements (Biondi et al, 2013), and observations of temperature in the UTLS of tropical weather disturbances (Davis et al, 2014). Note that the above list is only indicative, not exhaustive.…”

Cloud vertical structure over a tropical station obtained using long-term high-resolution radiosonde measurements

“…Finally, cloud top height can also be retrieved by applying geometrical methods to stereo observations (Moroney et al, 2002;Seiz et al, 2007;Wu et al, 2009). Global Navigation Satellite System (GNSS) radio occultation (RO) profiles were used to detect convective cloud top heights (Biondi et al, 2013). Recently, Biondi et al (2017) used GNSS RO profiles to detect the top altitude of volcanic clouds and analysed their impact on the thermal structure of UTLS.…”