NASA’s Contributions to the 2021 Aeolus Field Campaign: CPEX-AW

2021 ◽  
Author(s):  
Gail Skofronick-Jackson ◽  
Aaron Piña ◽  
Shuyi Chen
Keyword(s):  
High Altitude ◽  
Integrated Circuit ◽  
Satellite System ◽  
African Easterly Waves ◽  
Field Campaign ◽  
Easterly Waves ◽  
Weather Forecasts ◽  
Wind Lidar ◽  
Simulated Field ◽  
The Tropics

<p>In 2020, a joint NASA-ESA campaign focusing on the tropics was planned to take place in Cabo Verde. This campaign, now delayed to 2021, was designed to engage the broader scientific atmospheric dynamics community and to assist in calibrating and validating the recently launched ESA Aeolus wind lidar satellite system. This campaign is an opportunity to join the U.S. and European airborne wind lidar system teams addressing the Aeolus calibration and validation. Nominally, the NASA contribution is a follow-on to the Convective Processes Experiment (CPEX) field campaign which took place in 2017 (https://cpex.jpl.nasa.gov/). The 2021 field campaign will add an aerosol (A) and winds (W) component—CPEX-AW—and will provide opportunities to study the dynamics and microphysics related to the Saharan air layer, African easterly waves and jets, the marine atmospheric boundary layer, and convection that not only advance our understanding of tropical dynamics but also improve weather forecasts. The NASA component of the field campaign plans to begin intensive operations in early July 2021 and will continue until mid-August. Approximately 150 flight hours are planned on NASA’s DC-8 aircraft. Planned instruments are the Doppler Aerosol WiNd Lidar (DAWN), the High Altitude Lidar Observatory (HALO), the APR-3 radar (Ku, Ka, and W bands), the High Altitude Monolithic Microwave integrated Circuit (MMIC) Sounding Radiometer (HAMSR), and dropsondes. During Summer 2020, NASA’s team hosted a dry run of a simulated field campaign which included virtual flights. In this talk, we will discuss the plans for NASAs contributions to the 2021 Aeolus Field Campaign and present preliminary findings from using Aeolus data and CPEX-AW dry-run virtual flights.</p>

scholarly journals A Characterization of African Easterly Waves on 2.5–6-Day and 6–9-Day Time Scales

2013 ◽  
Vol 26 (18) ◽  
pp. 6750-6774 ◽  
Author(s):  
Man-Li C. Wu ◽  
Oreste Reale ◽  
Siegfried D. Schubert
Keyword(s):  
Time Scales ◽  
Ensemble Empirical Mode Decomposition ◽  
African Easterly Waves ◽  
Pressure System ◽  
Easterly Waves ◽  
African Easterly Jet ◽  
The North ◽  
Easterly Wave ◽  
Mode Decomposition ◽  
The Tropics

Abstract This study shows that the African easterly wave (AEW) activity over the African monsoon region and the northern tropical Atlantic can be divided in two distinct temporal bands with time scales of 2.5–6 and 6–9 days. The results are based on a two-dimensional ensemble empirical mode decomposition (2D-EEMD) of the Modern-Era Retrospective Analysis for Research and Applications (MERRA). The novel result of this investigation is that the 6–9-day waves appear to be located predominantly to the north of the African easterly jet (AEJ), originate at the jet level, and are different in scale and structure from the well-known low-level 2.5–6-day waves that develop baroclinically on the poleward flank of the AEJ. Moreover, they appear to interact with midlatitude eastward-propagating disturbances, with the strongest interaction taking place at the latitudes where the core of the Atlantic high pressure system is located. Composite analyses applied to the mode decomposition indicate that the interaction of the 6–9-day waves with midlatitude systems is characterized by enhanced southerly (northerly) flow from (toward) the tropics. This finding agrees with independent studies focused on European floods, which have noted enhanced moist transport from the ITCZ toward the Mediterranean region on time scales of about a week as important precursors of extreme precipitation.

scholarly journals A Recurrence Analysis of Multiple African Easterly Waves during Summer 2006

2020 ◽  
Author(s):  
Tiffany Reyes ◽  
Bo-Wen Shen
Keyword(s):  
Large Scale ◽  
Mesoscale Model ◽  
Recurrence Plot ◽  
Temporal Variations ◽  
Local Analysis ◽  
Lead Times ◽  
African Easterly Waves ◽  
Easterly Waves ◽  
Weather Forecasts

Accurate detection of large-scale atmospheric tropical waves, such as African easterly waves (AEWs), may help extend lead times for predicting tropical cyclone (TC) genesis. Since observed AEWs have comparable but slightly different periods showing spatial and temporal variations, local analysis of frequencies and amplitudes of AEWs is crucial for revealing the role of AEWs in the modulation of TC genesis. To achieve this goal, we investigate the recurrence plot (RP) method. A recurrence is defined when the trajectory of a state returns to the neighborhood of a previously visited state. To verify implementation of the RP method in Python and its capability for revealing a transition between different types of solutions, we apply the RP to analyze several idealized solutions, including periodic, quasiperiodic, chaotic and limit cycle solutions, and various types of solutions within the three- and five-dimensional Lorenz models. We then extend the RP analysis to two datasets from the European Centre for Medium-Range Weather Forecasts global reanalysis and global mesoscale model data in order to reveal the recurrence of multiple AEWs during summer 2006. Our results indicate that the RP analysis effectively displays the major features of time-varying oscillations and the growing or decaying amplitudes of multiple AEWs.

The waterscape at high altitudes

2017 ◽  
Author(s):  
Dean Jacobsen ◽  
Olivier Dangles
Keyword(s):  
High Altitude ◽  
Regional Climate ◽  
Water Source ◽  
Aquatic Systems ◽  
Running Waters ◽  
High Altitudes ◽  
Different Types ◽  
Geological Origin ◽  
Broad Variety ◽  
The Tropics

Chapter 2 presents the amazing variety of running waters, lakes, ponds, and wetlands found at high altitudes. These waterbodies are not equally distributed among the world’s high altitude places, but tend to be concentrated in certain areas, primarily determined by regional climate and topography. Thus, a large proportion of the world’s truly high altitude aquatic systems are found at lower latitudes, mostly in the tropics. The chapter presents general patterns in the geographical distribution of high altitude waters, and gives examples of some of the most extreme systems. High altitude aquatic systems and habitats cover a broad variety in dynamics and physical appearance. These differences may be related to, for example, water source (glacier-fed, rain-fed, or groundwater-fed streams), geological origin (e.g. glacial, volcanic, or tectonic lakes), or catchment slope and altitude (different types of peatland wetlands). This is exemplified and richly illustrated through numerous photos.

scholarly journals Trains of African Easterly Waves and Their Relationship to Tropical Cyclone Genesis in the Eastern Atlantic

2017 ◽  
Vol 145 (2) ◽  
pp. 599-616 ◽  
Author(s):  
Abdou L. Dieng ◽  
Saidou M. Sall ◽  
Laurence Eymard ◽  
Marion Leduc-Leballeur ◽  
Alban Lazar
Keyword(s):  
West African ◽  
Dynamical Structure ◽  
African Easterly Waves ◽  
The South ◽  
The West ◽  
Easterly Waves ◽  
West African Coast ◽  
African Coast ◽  
Tropical Depressions ◽  
The Relationship

In this study, the relationship between trains of African easterly waves (AEWs) and downstream tropical cyclogenesis is studied. Based on 19 summer seasons (July–September from 1990 to 2008) of ERA-Interim reanalysis fields and brightness temperature from the Cloud User Archive, the signature of AEW troughs and embedded convection are tracked from the West African coast to the central Atlantic. The tracked systems are separated into four groups: (i) systems originating from the north zone of the midtropospheric African easterly jet (AEJ), (ii) those coming from the south part of AEJ, (iii) systems that are associated with a downstream trough located around 2000 km westward (termed DUO systems), and (iv) those that are not associated with such a close downstream trough (termed SOLO systems). By monitoring the embedded 700-hPa-filtered relative vorticity and 850-hPa wind convergence anomaly associated with these families along their trajectories, it is shown that the DUO generally have stronger dynamical structure and statistically have a longer lifetime than the SOLO ones. It is suggested that the differences between them may be due to the presence of the previous intense downstream trough in DUO cases, enhancing the low-level convergence behind them. Moreover, a study of the relationship between system trajectories and tropical depressions occurring between the West African coast and 40°W showed that 90% of tropical depressions are identifiable from the West African coast in tracked systems, mostly in the DUO cases originating from the south zone of the AEJ.

scholarly journals How Can Existing Ground-Based Profiling Instruments Improve European Weather Forecasts?

2019 ◽  
Vol 100 (4) ◽  
pp. 605-619 ◽  
Author(s):  
A. J. Illingworth ◽  
D. Cimini ◽  
A. Haefele ◽  
M. Haeffelin ◽  
M. Hervo ◽  
...  
Keyword(s):  
Real Time ◽  
Traffic Control ◽  
Positive Impact ◽  
Weather Forecast ◽  
Weather Conditions ◽  
Time Data ◽  
Weather Forecasts ◽  
Forecast Models ◽  
Wind Lidar ◽  
Microwave Radiometers

Abstract To realize the promise of improved predictions of hazardous weather such as flash floods, wind storms, fog, and poor air quality from high-resolution mesoscale models, the forecast models must be initialized with an accurate representation of the current state of the atmosphere, but the lowest few kilometers are hardly accessible by satellite, especially in dynamically active conditions. We report on recent European developments in the exploitation of existing ground-based profiling instruments so that they are networked and able to send data in real time to forecast centers. The three classes of instruments are i) automatic lidars and ceilometers providing backscatter profiles of clouds, aerosols, dust, fog, and volcanic ash, the last two being especially important for air traffic control; ii) Doppler wind lidars deriving profiles of wind, turbulence, wind shear, wind gusts, and low-level jets; and iii) microwave radiometers estimating profiles of temperature and humidity in nearly all weather conditions. The project includes collaboration from 22 European countries and 15 European national weather services, which involves the implementation of common operating procedures, instrument calibrations, data formats, and retrieval algorithms. Currently, data from 265 ceilometers in 19 countries are being distributed in near–real time to national weather forecast centers; this should soon rise to many hundreds. One wind lidar is currently delivering real time data rising to 5 by the end of 2019, and the plan is to incorporate radiometers in 2020. Initial data assimilation tests indicate a positive impact of the new data.

scholarly journals Characteristics of African Easterly Waves

2003 ◽  
Vol 53 ◽  
pp. 91-108
Author(s):  
Robert W. Burpee
Keyword(s):  
African Easterly Waves ◽  
Easterly Waves

Abstract No Abstract available.

Statistical Characterization of Zonal and Meridional Ocean Wind Stress

2005 ◽  
Vol 22 (9) ◽  
pp. 1353-1372 ◽  
Author(s):  
Sarah T. Gille
Keyword(s):  
Wind Stress ◽  
Frequency Spectra ◽  
Low Frequencies ◽  
Statistical Characterization ◽  
Weather Forecasts ◽  
The Pacific ◽  
Meridional Winds ◽  
Wind Events ◽  
Environmental Prediction ◽  
The Tropics

Abstract Four years of ocean vector wind data are used to evaluate statistics of wind stress over the ocean. Raw swath wind stresses derived from the Quick Scatterometer (QuikSCAT) are compared with five different global gridded wind products, including products based on scatterometer observations, meteorological analysis winds from the European Centre for Medium-Range Weather Forecasts, and reanalysis winds from the National Centers for Environmental Prediction. Buoy winds from a limited number of sites in the Pacific Ocean are also considered. Probability density functions (PDFs) computed for latitudinal bands show that mean wind stresses for the six global products are largely in agreement, while variances differ substantially, by a factor of 2 or more, with swath wind stresses indicating highest variances for meridional winds and for zonal winds outside the Tropics. Higher moments of the PDFs also differ. Kurtoses are large for all wind products, implying that PDFs are not Gaussian. None of the available gridded products fully captures the range of extreme wind events seen in the raw swath data. Frequency spectra for the five gridded products agree with frequency spectra from swath data at low frequencies, but spectral slopes differ at higher frequencies, particularly for frequencies greater than 100 cycles per year (cpy), which are poorly resolved by a single scatterometer. In the frequency range between 10 and 90 cpy that is resolved by the scatterometer, spectra derived from swath data are flatter than spectra from gridded products and are judged to be flatter than ω−2/3 at all latitudes.

scholarly journals Validation of the Aura High Resolution Dynamics Limb Sounder geopotential heights

2014 ◽  
Vol 7 (2) ◽  
pp. 1001-1025
Author(s):  
L. L. Smith ◽  
J. C. Gille
Keyword(s):  
High Resolution ◽  
System Model ◽  
Weather Forecasts ◽  
Atmospheric Research ◽  
Earth Observing System ◽  
Medium Range ◽  
High Bias ◽  
Environmental Prediction ◽  
The Tropics ◽  
Data Screening

Abstract. Global satellite observations from the EOS Aura spacecraft's High Resolution Dynamics Limb Sounder (HIRDLS) of temperature and geopotential height (GPH) are discussed. The accuracy, resolution and precision of the HIRDLS version 7 algorithms are assessed and data screening recommendations are made. Comparisons with GPH from observations, reanalyses and models including European Center for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, Goddard Earth Observing System Model (GEOS) version 5, and EOS Aura Microwave Limb Sounder (MLS) illustrate the HIRDLS GPH have a precision ranging from 2 m to 30 m and an accuracy of ±100 m. Comparisons indicate HIRDLS GPH may have a slight low bias in the tropics and a slight high bias at high latitudes. Geostrophic winds computed with HIRDLS GPH qualitatively agree with winds from other data sources including ERA-Interim, NCEP and GEOS-5.

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