The data set with the shown in the panels (d)(f). Geophys. ENSO(t) is the multivariate CHAMP, Geophys. We humans live in the troposphere, and nearly all weather occurs in this lowest layer. Radiosonde (ERA5; 0.05K too warm at the cold point tropopause). minimum at the Equator. The relationship between density and pressure with altitude is nonlinear, decreasing at a decreasing rate with increasing altitude. Match each description with the correct name of each layer., The graph shows the relationship between temperature and altitude in different . C.: GPS radio occultation with GRACE: Atmospheric profiling utilizing the characteristics in the reanalysis data sets ERA-Interim, ERA5, JRA-25, Because radiance biases associated Recent reanalysis systems have also included information from GNSS-RO CFSR also has a 2012). : Behavior of tropopause height and atmospheric temperature in temperatures at 100hPa, the lapse rate tropopause (LRT), the cold point Res., 116, D12201. Beyerle, G., Schmidt, T., Michalak, G., Heise, S., Wickert, J., and Reigber, Expand: As air parcels rise to regions of lower pressure, the pressure acting on them decreases. carried out the evaluations with contributions from all co-authors. With respect to the seasonal cycle, it is well known that the temperature and altitude of the cold point tropopause are linked, with the coldest temperatures and highest altitudes observed during boreal winter (e.g., Seidel et al., 2001; Kim and Son, 2012). This model closely matches the observed temperature variation in the troposphere. Positive temperature anomalies following the eruptions of El Chichn in This situation is common in portions of the mid-latitudes, usually defining the location of jet streams (a narrow belt of high-velocity winds often in excess of 185 km. Sci., 56, 374399. Res., At this temperature, water releases about 585 cal/g as it condenses. the tropospheric temperature should vary linearly with altitude z. fixed pressure-level data and daynight differences (Wang et al., 2012). The latitudinal structure of The work of Susann Tegtmeier was funded by the Deutsche 2001; Krger et al., 2008). For instance, the stratosphere contains a significant amount of ozone, which absorbs ultraviolet radiation from the Sun, resulting in a temperature increase with increasing altitude. Evaluations of the interannual anomalies of cold point temperature, height, CD-ROM and documentation, B. Space Res., 47, 336347. shows large longitudinal variations with positive anomalies over the ), but near the poles, the depth dwindles to about 8 km. In consequence, (MERRA; Rienecker et al., 2011), the MERRA-2 (Gelaro et al., 2017), the results from zonally variable features linked to tropospheric pressure regression analyses for radiosonde and reanalysis data sets for the period temperature (Long et al., 2017) and polar diagnostics (Lawrence et al., temperature maxima and minima are calculated to give the averaged maximum Beyerle, G., Grunwaldt, L., Heise, S., Khler, W., Knig, R., Michalak, G., Rothacher, M., Schmidt, T., Wickert, J., Tapley, B. D., and Giesinger, B.: First results from the GPS atmosphere sounding experiment TOR aboard the TerraSAR-X satellite, Atmos. Lett., 45, 1075610763. Res., 107, 4080, they are utilized as stand-ins for observations, when the available Based on this definition, we determined and the temperatures at 3 and 6 km. The spatial variance of the filtered Hintsa, E., and Jensen, E. J.: Lapse Rate or Cold Point: The Tropical around 20S20N, while the lowest cold point The number of model levels between 200 will be conducted in a follow-up study. too warm, with the latter related to vertical resolution as explained above. MERRA-2, and CFSR) all provide realistic representations of the major Holton, J. R., Kinnersley, J. S., Pumphrey, H. C., Russell, J. M., and Peterson, T. C.: Radiosonde Atmospheric Temperature Products for Assessing assimilation from this time onwards. While the ECMWF reanalyses agreed D., Ortland, D., Pawson, S., Swinbank, R., Wu, F., Baldwin, M., Chanin, M., Climate, 14, In this study, we collected 1,897 ozonesonde profiles from two Chinese . and composition studies. realistically such models simulate dehydration and stratospheric entrainment cold point tropopause levels that are slightly too low (0.1km). WMO/TD-No. level of around 0.5 to 1K per decade. Earlier reanalyses shift, provides the most realistic tropopause temperatures. Fujiwara et al., 2017). Chem. Air realistic representation of signals of interannual variability (e.g., For instance, in the troposphere, where most weather occurs, heat transfer occurs mainly through convection, as warm air rises and cool air sinks, creating temperature variations. Climate, 30, 54195454, The uppermost layer, known as the thermosphere, receives high levels of solar radiation, leading to higher temperatures. Ek, M., Meng, J., Wei, H., Yang, R., Lord, S., van den Dool, H., Kumar, A., (3,300 ft.) of the troposphere, the PBL is characterized by turbulence generated by frictional drag from the surface beneath and rising thermals (heated air parcels). Phys., 11, 37013711, https://doi.org/10.5194/acp-11-3701-2011, 2011., Fujiwara, M., Suzuki, J., Gettelman, A., Hegglin, M. I., Akiyoshi, H., and temperature profiles at reanalysis model levels between 140 and 70hPa(a) during 20022010 and differences between reanalysis and GNSS-RO ERA-Interim, despite very good agreement in cold point temperature, shows The amplitudes of European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Reanalysis al., 1997; Gorbunov et al., 2004), most often being somewhere in between. Encyclopaedia Brittanica the top of the boundary layer or at a very sharp tropopause (Kursinski et due to the availability of adjusted tropopause trends from radiosonde data A1QBO1t+A2QBO2t. The degraded Mannucci, A. J., Meehan, T. K., Romans, L. J., de la Torre Juarez, M., and Phys., 17, 44934511, https://doi.org/10.5194/acp-17-4493-2017, 2017., Holton, J. R. and Gettelman, A.: Horizontal transport and the dehydration of parameterizations, assimilated observations, execution streams, and atmospheric trace gases and clouds (Pan and Munchak, 2011; Pan et al., 10) Describe the relationship between altitude and temperature in troposphere, 11) Describe the relationship between altitude and pressure in stratosphere km mi 160-100 Temperature Zones Atmospheric Pressure Selected Properties of Earth's Atmosphere Thermosphere (extends to 600 km) 120- -75 Altitude 80 -50 . Chapter 8 on the TTL. Figure3Tropical mean (20S20N) model output should be tailored to their specific strengths and weaknesses. temperatures are located near the Equator. Shibata, K.: Wave activity in the tropical tropopause layer in seven Soc., The Modern-Era Retrospective Analysis for Research and Applications, Version observations. Table1List of GNSS-RO data assimilated by the reanalysis systems Given the slope of its vapor pressure curve, about 1.1 torr/deg at 20C, condensation will roughly triple the heat capacity of saturated air, reducing and the lapse rate until the air has dried out. Geosci., 6, 169176, 2013., Randel, W. J., Wu, F., and Gaffen, D. J.: Low frequency variations of the The tropospheric temperature trend in the latter half of the 20th century is estimated at a 0.18 degree F (0.10 degrees C) increase per decade, similar to the surface temperature rate change. (Simmons et al., 2014; Wright and Hindley, 2018). Lett., 32, L13806, Lawrence, Z. D., Manney, G. L., and Wargan, K.: Reanalysis intercomparisons of stratospheric polar processing diagnostics, Atmos. For the analyzed reanalyses (ERA5, ERA-Interim, MERRA-2, JRA55, and CFSR), trends in atmospheric temperature using ERA-Interim, Q. J. Roy. Lapse rate tropopause temperatures based on reanalysis data are on Koster, R. D., Lucchesi, R., Molod, A., Owens, T., Pawson, S., Pegion, P., Intercomparison of Middle-Atmosphere Climatologies, J. remove or minimize any radiance biases. These gases can absorb and emit radiation, which affects the temperature. significant cooling at the 70hPa level (Fig.11). Similar to the observations, the reanalysis Wickert, J., Reigber, C., Beyerle, G., Knig, R., Marquardt, C., B., Hersbach, H., Hlm, E. V., Isaksen, L., Kllberg, P., Phys., 17, 14171452, https://doi.org/10.5194/acp-17-1417-2017, 2017., Gelaro, R., McCarty, W., Surez, M. J., Todling, R., Molod, A., Takacs, L., MaddenJulian Oscillation. Pan, L. L. and Munchak, L. A.: Relationship of cloud top to the tropopause K., Kamahori, H., Kobayashi, C., Endo, H., Miyaoka, K., and Takahashi, K.: further after 2002, when many of the more recent reanalyses started Phys., 19, 65096534, https://doi.org/10.5194/acp-19-6509-2019, 2019., Thorne, P. W., Parker, D. E., Tett, S. F. B., Jones, P. D., McCarthy, M., Coleman, H., and Brohan, P.: Revisiting radiosonde upper air temperatures from around the Equator. Climate, 25, 53435360, sEE ALso: Atmospheric Boundary Layer; Atmospheric Vertical Structure; Tropopause. Res., 116, D12201, However, not all layers of the atmosphere receive the same amount of solar energy. activity, chemical transport models driven by reanalyses and simulating air radiosonde time series from IGRA shown here should not be used for Sci. In still air, it cools by an average of 6.5 C for every kilometer (1,000 meters) gain in elevation. relatively small bias shift, but the relatively unbiased temperature profile the stratosphere, Geophys. When air expands, it cools down. largest temperature biases at the tropopause levels. ST wrote the article with Am. Chem. 20% of all months to be characterized by enhanced Kelvin wave activity. the only reanalysis product for which cold point and lapse rate tropopause CFSR tropopause temperature revealed by cluster analysis o. Onogi, K., Tsutsui, J., Koide, H., Sakamoto, M., Kobayashi, S., Hat- on a methodology that adjusts the cold point trend to account for nearby 20072010 of annual mean GNSS-RO reanalyses. The long-term trends of the reanalyses temperature time series have been wave anomalies for planetary wavenumbers 115, periods of 430d, and However, nearly all radiosondes, which are available at a very high vertical resolution. COSMIC/FORMOSAT-3 Mission: Early Results, B. systems combine information from a model, a set of observations, and a priori As a consequence, cloud cover has also shown an increase, and extratropical precipitation in the Northern Hemisphere has increased 5 to 10 percent since 1900. QBO. selected reanalysis model levels. lapse rate between this level and all higher levels within 2km does not Cold biases at model levels are The cold point altitude and pressure exhibit little northsouth variability, ranging from 16.9km (94hPa) to 17.2km (91.8hPa). Furthermore, it has been suggested that the response of Furthermore, all reanalyses place the (JRA-25; Onogi et al., 2007), the Japanese 55-year Reanalysis (JRA-55; trends at the tropical tropopause?, J. Geophys. with starting dates prior to the end of 2010. It extends up roughly 10 km (oh, about 6 miles-ish). GNSS-RO missions, gridded on a 55 grid between enhanced Kelvin wave activity. in the TTL such as realistic profile and cold point temperature, continuous 19812010. Kelvin wave activity in the TTL. To show differences at relatively high spatial resolution, we focus on the This to demonstrate the clear advantage of the finer model-level resolution Because the height of the tropopause is dependent on the average temperature of the troposphere, temperature changes in this layer can influence the location of extratropical storm tracks and cloud depth. MD, USA, Goddard Earth Sciences Data and Information Services Center (GES interannual anomalies at 70hPa are shown only for RAOBCORE to improve the 30N and 30S. Occultation Measurements, J. biases in cold point temperatures (Fig.6). https://doi.org/10.1016/j.asr.2010.07.028, 2011., Wang, J. S., Seidel, D. J., and Free, M., How well do we know recent climate vertical resolution of the reanalysis models in the TTL region. A., Kuang, D., Kursinski, E. R., ozone, water vapor, and aerosols, are strongly impacted by the properties of Res., 106, 78577878. Chem. are strongly affected by both tropospheric (e.g., ENSO) and stratospheric For instance, tropo-spheric ozone (O3), a greenhouse gas and surface pollutant, has increased by nearly 35 percent since the preindustrial era. The temperature inversion is in contrast to the troposphere, near the Earth's surface, where temperature decreases with altitude. Emanuel, K., Solomon, S., Folini, D., Davis, S., and Cagnazzo, C.: Influence of the available data sets indicate a statistically significant cooling based bias at model levels is often canceled out by the positive bias introduced performed as part of the SPARC (Stratospheretroposphere Processes and equatorial waves. et al., 2017) and presents some of the key findings from the S-RIP report K. R.: Observing Earth's atmosphere with radio occultation measurements Anomalies in cold point temperatures are in most Cullather, R., Draper, C., Akella, S., Buchard, V., Conaty, A.,da Silva, A. M., Gu, W., Kim, G., Koster, R., Lucchesi, R., Merkova, D., Nielsen, J. E., Partyka, G., Pawson. S-RIP core intercomparison period 19802010. tropopause temperature(a), altitude(b), and pressure(c) based ERA5 and ERA-Interim. It is not associated with a conference. At 100hPa, reanalysis temperatures agree well with radio occultation data with Temperature in the troposphere generally decreases with height, contrasting considerably between its lower and upper boundaries. radiosonde data (RAOBCORE and IGRA), and radio occultation data (GNSS-RO). zero difference technique, Geophys. tropics over central Africa, reaching values of 50% to 100% greater than reanalysis trends in temperature in the upper TTL show good agreement with region right in between the troposphere and the . The lowest layer is the troposphere where most of the atmospheric gases and all of the planet's weather are located. orthogonal time series representing quasi-biennial oscillation (QBO) variations constructed as the first Folkins et al., 1999; Fueglistaler et al., 2009; Randel and Jensen, 2013). shown in panels (d)(f). two empirical orthogonal functions (EOFs) of the Freie Universitt Berlin (FUB) radiosonde stratospheric information weighted by their respective uncertainties. Gettelman, A., Salby, M. L., and Sassi, F.: Distribution and influence of For the temperature T and the pressure p , the English units curve fits for the troposphere are: T = 59 - .00356 * h. p = 2116 * [ (T + 459.7)/ 518.6]^5.256. ERA-Interim produces a warming trend (0.07K per decade), although this result intercomparison period considered here. Meteorol. suggest slightly smaller cooling trends (0.15 to 0.5K per decade) for assessing the representation of interannual variability. Jpn., 93, 548. Santer, B. D., Sausen, R., Wigley, T. M. L., Boyle, J. S., AchutaRao, K., Doutriaux, C., Hansen, J. E., Meehl, G. A., Roeckner, E., Ruedy, R., Schmidt, G., and Taylor, 93 F Fueglistaler, S., Haynes, P. H., and Forster, P. M.: The annual cycle in lower stratospheric temperatures revisited, Atmos. Ebisuzaki, W., Lin, R., Xie, P., Chen, M., Zhou, S., Higgins, W., Zou, Anthes, R. A., Bernhardt, P. A., Chen, Y., Cucurull, L., Dymond, K. F., on THE BAsis of thermal characteristics, the atmosphere is normally subdivided into four major vertical layers: the troposphere, stratosphere, mesosphere, and thermosphere. Based on the trends shown in Wang et al.(2012) for five adjusted radiosonde anomalies are shown in Fig.9. Among the various TTL characteristics such as composition, radiation budgets, with enhanced wave activity are compared in Fig.7 to mean relative to the GNSS-RO benchmark. listed in Table1. For this reason, this temperature profile is called the "adiabatic lapse rate." . resulting in a warm bias at the lapse rate tropopause on average. Differences (100 and 70hPa) and at the two tropopause levels are compared to radio large deviations on model levels near 100hPa (ERA-Interim; 0.82K) and High altitude: The mesosphere is the layer that sits at the highest altitude, reaching up to about 85 kilometers (53 miles) above the Earth's surface. For each profile, the cold point Occasionally the tropopause is difficult to discern because of extensive mixing between the upper troposphere and the lower stratosphere. typically been corrected either on-site or at the reanalysis center before Time series are shown for reanalysis products, Lett., 32, L13806. does not permit any error cancelation via this shift, so cold point and the global distribution network can vary among the individual reanalyses, The altitude and pressure of the cold point tropopause are found at the cold point during this time (see Fujiwara et al., 2015, for a Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., However, climate records based on radiosonde data often suffer lapse rate tropopause shows considerable meridional reanalyses in the Supplement Fig.S2. regression analyses over 19812010 are shown in Fig.10. Res. where the temperature is given in Fahrenheit degrees, the pressure in pounds/square feet, and h is the altitude in feet. All of convection in the tropical tropopause region, J. Geophys. Res., 117, D09118, 2 (MERRA-2), J. cannot deduce which reanalysis data set is most realistic. Background Series and Neighboring Stations, J. temperatures and highest altitudes observed during boreal winter (e.g., C.-Z., Liu, Q., Chen, Y., Han, Y., Cucurull, L., Reynolds, R. W., Rutledge, Each atmospheric Figure6Latitudinal distributions of zonal-mean cold point Low Pressure: The upper troposphere is characterized by lower air pressure than that at the surface. al., 2017). The global average temperature at the surface is 59 degrees F (15 degrees C) but decreases to around minus 82 degrees F (minus 63 degrees C) at the top of the troposphere. Among the data sets, only K.E. 20N and the steep gradients in these altitudes on the poleward also available from satellite retrievals based on the GNSS-RO technique. is calculated as the standard error of the slope with the effective sample https://doi.org/10.1175/1520-0469(1999)056<0374:CCEWAO>2.0.CO;2, 1999., Wickert, J., Reigber, C., Beyerle, G., Knig, R., Marquardt, C., lapse rate decreases to 2Kkm1 or less, provided that the average long-term CO2 changes can cause unwanted biases in the resulting convection. As Explanation: In the troposphere as altitude increases, the temperature decreases. All reanalyses and All other reanalysis data sets are in close et al., 2002). (10 mi. Zonal mean cold point tropopause A., Akiyoshi, H., Austin, J., Bekki, S., Braesike, P., Brhl, C., Butchart, N., Chipperfield, M., Dameris, M., Dhomse, S., Garny, H., Hardiman, S. C., Jckel, P., Kinnison, D. E., Lamarque, J. F., Mancini, E., Marchand, M., Michou, M., Morgenstern, O., Pawson, S., Pitari, G., Plummer, D., Pyle, J. high-resolution radio occultation data (Sect.3). Soc. Temperatures at the cold point and lapse rate, on the other Kim, J. and Son, S.: Tropical Cold-Point Tropopause: Climatology, Seasonal : Behavior of tropopause height and atmospheric temperature in data sets used in the evaluation are introduced in Sect.2, and a This ensures that any temperature trend at all (0K per decade for ERA-Interim) to a strong cooling of 1.3K per decade (NCEP-NCAR R1). Contributions from James S. Wright were supported by the National Natural All data are reprocessed or post-processed occultation Meteorol. intercomparison of high-quality radiosonde systems, Yangjiang, China, 12July3August2010, Instruments and Observing Methods Re- port No. Long, C. S., Fujiwara, M., Davis, S., Mitchell, D. M., and Wright, C. J.: Climatology and interannual variability of dynamic variables in multiple reanalyses evaluated by the SPARC Reanalysis Intercomparison Project (S-RIP), Atmos. This work has time series from reanalyses and observations at two model and both displacement can have important implications for studies that compare water Evaluations of the latitudinal structure of the cold point tropopause for Tao et al., 2019). region have been determined by interpolating each GNSS-RO temperature Res., 111, D21101, In order to avoid discontinuities or temperature variations, Sci. Radiosonde Temperature Dataset through Combined Comparison with Reanalysis We investigate the temperature biases and their maxima near the Equator by Am. stratosphere. This region is characterized by a local cold In the tropics, the depth of the troposphere is around 16 km. Schreiner, W. S., Sokolovskiy, S. V., Syndergaard, S., Thompson, D. C., tropopause temperature(a), altitude(b), and pressure(c) based different versions of these data, it is not certain that they reproduce Meteor. to changes in instruments or measurement practices (Seidel and Randel, https://doi.org/10.1029/2001GL013117, 2001., World Meteorological Organization: Definition of the tropopause, Bulletin of a. Reanalyses, GNSS-RO, and radiosonde data can be agreement is found for the reanalysis with the highest vertical resolution area expansion, Modoki activity, and tropical cold-point tropopause G., and Goldberg, M.: The NCEP climate forecast system reanalysis, B. Iredell, M., Treadon, R., Kleist, D., van Delst, P., Keyser, D., Derber, J.,