Validation of Atmospheric Infrared Sounder temperature and moisture profiles over tropical oceans and their impact on numerical simulations of tropical cyclones

2010 ◽  
Vol 115 (D24) ◽  
Author(s):  
Zhaoxia Pu ◽  
Lei Zhang
Keyword(s):  
Numerical Simulations ◽  
Tropical Cyclones ◽  
Atmospheric Infrared Sounder ◽  
Tropical Oceans ◽  
Moisture Profiles

scholarly journals Impact of Atmospheric Infrared Sounder Data on the Numerical Simulation of a Historical Mumbai Rain Event

2008 ◽  
Vol 23 (5) ◽  
pp. 891-913 ◽  
Author(s):  
Randhir Singh ◽  
P. K. Pal ◽  
C. M. Kishtawal ◽  
P. C. Joshi
Keyword(s):  
Numerical Experiments ◽  
Mesoscale Model ◽  
Heavy Rain ◽  
Heavy Rainfall Event ◽  
Rain Event ◽  
Intense Rainfall ◽  
Atmospheric Infrared Sounder ◽  
Rainfall Analysis ◽  
Moisture Profiles ◽  
The Impact

Abstract In this paper, the three-dimensional variational data assimilation scheme (3DVAR) in the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (Penn State–NCAR) Mesoscale Model (MM5) is used to study the impact of assimilating Atmospheric Infrared Sounder (AIRS) retrieved temperature and moisture profiles on board Aqua, a satellite that is part of NASA’s Earth Observing System. A record-breaking heavy rain event that occurred over Mumbai, India, on 26 July 2005 with 24-h rainfall exceeding 94 cm was used for the simulation. By analyzing the data from the NCEP–NCAR reanalysis, possible causes of this heavy rainfall event were investigated. The temporal evolution of meteorological fields clearly indicates the formation of midtropospheric mesoscale vortices over Mumbai that exactly coincides with the duration of the intense rainfall. Analysis also indicated the midlevel dryness with higher temperature and moisture in the lower levels. This midlevel dryness with high temperature and moisture in the lower levels increases the conditional instability, which was conducive for the development of very severe local thunderstorms. The midtropospheric mesoscale vortices existed over Mumbai together with lower-level instability and the active monsoon conditions over the west coast resulted in intense rainfall, on the order of 94 cm in 24 h. Numerical experiments were conducted, with two nested domains (45- and 15-km grid spacing). The assimilation of the AIRS-retrieved temperature and moisture profiles produced significant impacts on the location and intensity of the simulated rainfall. It is seen from the numerical experiments that the assimilation of AIRS data could produce the structure of mesoscale vortices, and lower-level thermodynamics and convergence much more realistically compared with the control simulation. The spatial distribution of the rainfall from the simulation using AIRS data was more realistic than that without AIRS data. To make the quantitative comparison of the predicted rainfall with the observed one, the equitable threat score and bias were calculated for different threshold values of rainfall. Inclusion of AIRS data significantly improved the precipitation as indicated by the equitable threat scores and biases for almost all of the threshold rainfall categories.

scholarly journals Genesis and maintenance of "Mediterranean hurricanes"

2005 ◽  
Vol 2 ◽  
pp. 217-220 ◽  
Author(s):  
K. Emanuel
Keyword(s):  
Numerical Simulations ◽  
Mediterranean Sea ◽  
Tropical Cyclones ◽  
Satellite Images ◽  
Baroclinic Instability ◽  
Small Areas ◽  
Warm Core ◽  
Surface Enthalpy ◽  
The Mediterranean ◽  
Cyclonic Storms

Abstract. Cyclonic storms that closely resemble tropical cyclones in satellite images occasionally form over the Mediterranean Sea. Synoptic and mesoscale analyses of such storms show small, warm-core structure and surface winds sometimes exceeding 25ms-1 over small areas. These analyses, together with numerical simulations, reveal that in their mature stages, such storms intensify and are maintained by a feedback between surface enthalpy fluxes and wind, and as such are isomorphic with tropical cyclones. In this paper, I demonstrate that a cold, upper low over the Mediterranean can produce strong cyclogenesis in an axisymmetric model, thereby showing that baroclinic instability is not necessary during the mature stages of Mediterranean hurricanes.

scholarly journals Impacts of Radiation and Cold Pools on the Intensity and Vortex Tilt of Weak Tropical Cyclones Interacting with Vertical Wind Shear

2020 ◽  
Vol 77 (2) ◽  
pp. 669-689 ◽  
Author(s):  
Rosimar Rios-Berrios
Keyword(s):  
Numerical Simulations ◽  
Tropical Cyclones ◽  
Structural Changes ◽  
Prediction Models ◽  
Weather Prediction ◽  
Vertical Wind Shear ◽  
Unexpected Finding ◽  
Cold Pools ◽  
Tropical Depressions ◽  
Microphysical Processes

Abstract Idealized numerical simulations of weak tropical cyclones (e.g., tropical depressions and tropical storms) in sheared environments indicate that vortex tilt reduction and convective symmetrization are key structural changes that can precede intensification. Through a series of ensembles of idealized numerical simulations, this study demonstrates that including radiation in the simulations affects the timing and variability of those structural changes. The underlying reason for those effects is a background thermodynamic profile with reduced energy available to fuel strong downdrafts; such a profile leads to weaker lower-tropospheric ventilation, greater azimuthal coverage of clouds and precipitation, and smaller vortex tilt with radiation. Consequently, the simulations with radiation allow for earlier intensification at stronger shear magnitudes than without radiation. An unexpected finding from this work is a reduction of both vortex tilt and intensity variability with radiation in environments with 5 m s−1 deep-layer shear. This reduction stems from reduced variability in nonlinear feedbacks between lower-tropospheric ventilation, cold pools, convection, and vortex tilt. Sensitivity experiments confirm the relationship between those processes and suggest that microphysical processes (e.g., rain evaporation) are major sources of uncertainty in the representation of weak, sheared tropical cyclones in numerical weather prediction models.

scholarly journals Tropical Cyclone–Induced Upper-Ocean Mixing and Climate: Application to Equable Climates

2008 ◽  
Vol 21 (4) ◽  
pp. 638-654 ◽  
Author(s):  
Robert L. Korty ◽  
Kerry A. Emanuel ◽  
Jeffery R. Scott
Keyword(s):  
Carbon Dioxide ◽  
Heat Flux ◽  
Surface Water ◽  
Tropical Cyclone ◽  
Dynamic Response ◽  
Tropical Cyclones ◽  
Climate Changes ◽  
Tropical Oceans ◽  
Warm Surface Water ◽  
Upper Ocean Mixing

Abstract Tropical cyclones instigate an isolated blast of vigorous mixing in the upper tropical oceans, stirring warm surface water with cooler water in the thermocline. Previous work suggests that the frequency, intensity, and lifetime of these storms may be functions of the climate state, implying that transient tropical mixing could have been stronger during warmer equable climates with higher concentrations of carbon dioxide. Stronger mixing of the tropical oceans can force the oceans’ meridional heat flux to increase, cooling tropical latitudes while warming higher ones. This response differs significantly from previous modeling studies of equable climates that used static mixing; coupling mixing to climate changes the dynamic response. A parameterization of mixing from tropical cyclones is developed, and including it leads to a cooling of tropical oceans and a warming of subtropical waters compared with control cases with fixed mixing. The mixing penetration depth regulates the magnitude of the response.

scholarly journals Evaluating the Absolute Calibration Accuracy and Stability of AIRS Using the CMC SST

2020 ◽  
Vol 12 (17) ◽  
pp. 2743
Author(s):  
Hartmut H. Aumann ◽  
Steven E. Broberg ◽  
Evan M. Manning ◽  
Thomas S. Pagano ◽  
Robert C. Wilson
Keyword(s):  
Time Series ◽  
Standard Deviation ◽  
Absolute Calibration ◽  
Atmospheric Infrared Sounder ◽  
Clear Sky ◽  
Tropical Oceans ◽  
Atmospheric Window ◽  
Surface Skin Temperature ◽  
Calibration Accuracy ◽  
The Difference

We compare the daily mean and standard deviation of the difference between the sea surface skin temperature (SST) derived from clear sky Atmospheric InfraRed Sounder (AIRS) data from seven atmospheric window channels between 2002 and 2020 and collocated Canadian Meteorological Centre (CMC) SST data from the tropical oceans. After correcting the mean difference for cloud contamination and diurnal effects, the remaining bias relative to the CMC SST, is reasonably consistent with estimates of the AIRS absolute accuracy based on the uncertainty of the pre-launch calibration. The time series of the bias produces trends well below the 10 mK/yr level required for climate change evaluations. The trends are in the 2 mK/yr range for the five window channels between 790 and 1231 cm−1, and +5 mK/yr for the shortwave channels. Between 2002 and 2020, the time series of the standard deviation of the difference between the AIRS SST and the CMC SST dropped fairly steadily to below 0.4 K in several AIRS window channels, a level previously only seen in gridded SST products relative to the Argo buoys.

scholarly journals A Latent Heat Retrieval and Its Effects on the Intensity and Structure Change of Hurricane Guillermo (1997). Part II: Numerical Simulations

2012 ◽  
Vol 69 (11) ◽  
pp. 3128-3146 ◽  
Author(s):  
Stephen R. Guimond ◽  
Jon M. Reisner
Keyword(s):  
Numerical Simulations ◽  
Tropical Cyclones ◽  
Latent Heat ◽  
Inner Core ◽  
Doppler Radar ◽  
Model Parameters ◽  
Saturation State ◽  
Wind Structure ◽  
Tangential Wind ◽  
Airborne Doppler Radar

Abstract In Part I of this study, a new algorithm for retrieving the latent heat field in tropical cyclones from airborne Doppler radar was presented and fields from rapidly intensifying Hurricane Guillermo (1997) were shown. In Part II, the usefulness and relative accuracy of the retrievals is assessed by inserting the heating into realistic numerical simulations at 2-km resolution and comparing the generated wind structure to the radar analyses of Guillermo. Results show that using the latent heat retrievals as forcing produces very low intensity and structure errors (in terms of tangential wind speed errors and explained wind variance) and significantly improves simulations relative to a predictive run that is highly calibrated to the latent heat retrievals by using an ensemble Kalman filter procedure to estimate values of key model parameters. Releasing all the heating/cooling in the latent heat retrieval results in a simulation with a large positive bias in Guillermo’s intensity that motivates the need to determine the saturation state in the hurricane inner-core retrieval through a procedure similar to that described in Part I of this study. The heating retrievals accomplish high-quality structure statistics by forcing asymmetries in the wind field with the generally correct amplitude, placement, and timing. In contrast, the latent heating fields generated in the predictive simulation contain a significant bias toward large values and are concentrated in bands (rather than discrete cells) stretched around the vortex. The Doppler radar–based latent heat retrievals presented in this series of papers should prove useful for convection initialization and data assimilation to reduce errors in numerical simulations of tropical cyclones.

scholarly journals Reduced tropical cyclone densities and ocean effects due to anthropogenic greenhouse warming

2020 ◽  
Vol 6 (51) ◽  
pp. eabd5109
Author(s):  
Jung-Eun Chu ◽  
Sun-Seon Lee ◽  
Axel Timmermann ◽  
Christian Wengel ◽  
Malte F. Stuecker ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
Cold Water ◽  
Relevant Information ◽  
Forced Response ◽  
System Model ◽  
Greenhouse Warming ◽  
Earth System ◽  
Tropical Oceans ◽  
Ocean Models ◽  
Hadley Cells

Tropical cyclones (TCs) are extreme storms that form over warm tropical oceans. Along their tracks, TCs mix up cold water, which can further affect their intensity. Because of the adoption of lower-resolution ocean models, previous modeling studies on the TC response to greenhouse warming underestimated such oceanic feedbacks. To address the robustness of TC projections in the presence of mesoscale air-sea interactions and complex coastal topography, we conduct greenhouse warming experiments using an ultrahigh-resolution Earth System Model. We find that a projected weakening of the rising branches of the summer Hadley cells suppresses future TC genesis and TC-generated ocean cooling. The forced response is similar to recent observational trends, indicating a possible emergence of the anthropogenic signal beyond natural variability levels. In the greenhouse warming simulations, landfalling TCs intensify, both in terms of wind speed and associated rainfall. Our modeling results provide relevant information for climate change adaptation efforts.

scholarly journals Secondary Eyewall Formation in Tropical Cyclones by Outflow–Jet Interaction

2017 ◽  
Vol 74 (6) ◽  
pp. 1941-1958 ◽  
Author(s):  
Yi Dai ◽  
Sharanya J. Majumdar ◽  
David S. Nolan
Keyword(s):  
Wind Speed ◽  
Numerical Simulations ◽  
Tropical Cyclones ◽  
Deep Convection ◽  
Stratiform Cloud ◽  
Jet Interaction ◽  
Secondary Eyewall Formation ◽  
Stratiform Region ◽  
Upper Level ◽  
Convective Cells

Abstract This study uses idealized numerical simulations to show that the interaction between tropical cyclones and a midlatitude jet can result in secondary eyewall formation. It is argued that the eddy activity by the outflow–jet interaction can enhance the upper-level outflow, thereby creating an asymmetric stratiform region outside of the primary eyewall. Numerous long-lasting deep convective cells are able to form in the stratiform cloud, creating forcing necessary for the secondary eyewall. The low-level inflow and the TC’s primary circulation advect the deep convective cells inward and cyclonically. The secondary eyewall forms after the deep convection has surrounded the TC. In contrast, numerical simulations without the jet do not show secondary eyewall formation. For moderately strong jets of wind speed 15–30 m s−1, there is little sensitivity to the jet strength. There is sensitivity to the distance between the jet and the TC, with secondary eyewall formation evident when their separation is 15° latitude but not when the separation exceeds 20°.

Sign in / Sign up

Export Citation Format

Share Document