1c: Jule G. Charney

His theoretical contributions include seminal papers on the instability mechanisms that give rise to baroclinic waves and tropical cyclones, the central role of deep cumulus convection in the tropical general circulation, and geostrophic turbulence. Promoted research on the general circulation through his leadership in the Global Atmospheric Research Program.

Photo provided by Nora Charney.

1d: Edward N Lorenz

Best known for his work on the limits to deterministic predictability, but us but also a pioneer in general circulation research. His elegant (1955) formalism in which he introduced the concept of available potential energy is widely used in diagnostics of the mechanical energy cycle. His (1967) monograph helped shape the field and give it direction.

Photo provided by Dennis L. Hartmann.

1.2a: Verner Suomi

World leader in the development of satellite imagery and remote sensing of the state atmosphere. Inventor and tireless promoter of satellite-based instrumentation and visionary in recognizing that it would soon become the backbone of the global observing system.

1.2b: Anthony Hollingsworth

Led the effort to advance the state of the art of data assimilation at the European Centre for Medium Range Forecasts (ECMWF).

Photo provided by the ECMWF Archive.

1.2c

Timeline for the development of global observing and data assimilation systems that provide the basis for the reanalysis products used in many of the figures shown in this text.

1.3a: The "window channel" between water vapor absorption bands, an indicator of cloud-top "brightness temperature".

The scale in the color bar has been designed to be highly informative, yet relatively straightforward to interpret. It is used in the videos provided by NOAA/CIMSS in the Animations Library.

---

The image for Hurricane Larry in the left panel is typical of deep cumulus convection with cloud tops below the tropical cold point tropopause, which are rendered in warm colors and decks of middle clouds in greens and blues. Low clouds are rendered in light gray such that they resemble their counterparts in visible imagery. The deepest clouds, which reach the vicinity of the cold point, where brightness temperatures are below -70°C, are rendered in a second grayscale, topped off with pink (below -80°C) and yellow (below -90°C).

The image in the right panel shows the cloud produced by the Tonga eruption, which reached the stratopause level. Its top spans a wider range of colors, with brightness temperatures as low as -75°C. It is a bit more challenging to interpret because the brightness temperature of the cloud when its top was in the upper stratosphere, was comparable to that of typical middle cloud decks.

1.3b: The "water vapor" channels correspond to absorption bands for which the level of unit optical depth (in clear air) is in the troposphere.

The image shown here is based on one of several channels used in the water vapor imagery provided by NOAA/CIMSS. It corresponds to the strongest band. whose level of unit optical depth is in the upper troposphere. The other channels correspond to weaker bands with lower levels of unit optical depth. The water vapor imagery also shows the signature of high clouds, mainly deep convective clouds in the tropics and in the summer hemisphere, which exhibit the lowest radiances in this channel.

In the color palette for this band, the lowest radiances, which correspond to cloud tops, are rendered in green and white. The blues, fading into yellows are indicative of progressively d higher equivalent temperatures of the air molecules emitting the radiation. Animations 12.5.2-1 and 15.2-1 were created using this color palette.

1.3-4

“Sandwich imagery”(bottom layer) created by colorizing high resolution visible imagery (HRV, middle layer) usung a color table based on IR window imagery (top panel).

Provided by Martin Cetvak.

1.4-1a

Definitions of zonal and time means, eddies and transients.

1.4-1b

Partitioning of variance and covariance statistics into contributions from time and zonal means, standing eddies, etc.

1.4-1c

Display formats.

1.4-2a

The zonally-varying jet streams; the Northern Hemisphere wintertime stationary wave ridges and troughs, features introduced in Fig. 1.4 of the text.

1.4-2b

Trade wind and westerly belts, subtropical highs, subpolar lows, features introduced in Fig. 1.12 of the text. The subtropical There are five subtropical anticyclones, all of which are year-round features. Seasonal variations in their configurations can be viewed in Animation 1.4-2. In the winter hemisphere, they correspond to the maxima in a zonally symmetric ring of high pressure, whereas in the summer hemisphere, the zonally symmetric component is less pronounced and the zonal asymmetries stand out more clearly.

1.4-2c

Indo-Pacific warm pool and eastern Pacific and Atlantic equatorial cold tongues, features introduced in Fig. 1.9 of the text.

1.4-2d

The Pacific and Atlantic intertropical convergence zones (ITCZs), the South Pacific convergence zone (SPCZ). the equatorial dry zones, and the extratropical storm tracks, features introduced in Fig. 1.14 of the text.

1.4-2e

The Pacific ITCZ, a snapshot, from Wikipedia.

1.4-2f

The Pacific ITCZ, the SPCZ, and the equatorial dry zones, are features introduced in Fig. 1.15 of the text.

1.4-2g

The rain belts of the summer monsoons, features introduced in Fig. 1.15 of the text.

1.4-2h

The zonally averaged Northern and Southern Hemisphere tropospheric jet streams, surface westerly wind belts, and stratospheric polar night jet streams, features introduced in Fig. 1.19 of the text.

1.4-2i

The annual mean Brewer-Dobson circulation, introduced in Fig. 1.29 of the text shown together with the Hadley circulations.

1.4-2j

The seasonal (DJF and JJA) mean Brewer-Dobson circulation is shown together with the Hadley circulation.

1.5a

Left panel; wavenumber-frequency spectrum of atmospheric motions with Rossby waves, gravity waves, and acoustic waves dominant at successively higher wavenumber and frequency (smaller wavelength and shorter period) ranges. The Navier Stokes Equations are capable of representing all three kinds of waves, the primitive equations gravity and Rossby waves and the quasi-geostrophic equations only Rossby waves.

The three systems of equations are summarized in the right panel: the dependent variables (top row), the prognostic equations in black and the diagnostic equations in red.

1.6a: Norman Phillips

Norman Phillips is credited with the development of the first general circulation model, in 1956) -- a 2-layer, hemispheric quasigeostrophic model that was capable of simulating the troposphere jet stream, the Hadley and Ferrel cells, the tradewinds, and extratropical westerlies.

1.6b: Joseph Smagorinsky

As director of the NOAA laboratory (later named the Geophysical Fluid Dynamics Laboratory (GFDL) he assembled and led the team of scientists that developed the first generation of multi-level, global general circulation models based on the primitive equations and demonstrated their utility in atmospheric research.

1.6c: Syukuro Manabe

Hired by Smagorinsky in 1959. Played a key role in the early model development. His contributions include the development of the convective parameterization schemes called “convective adjustment” based on the concept of a radiative-convective equilibrium and the identification of important feedbacks that mediate the sensitivity of the climate system to anthropogenic and other forcings.

1.6d: Manabe and Smagorinsky pictured together

1.6e: Kikuro Miyakoda

An early contributor to the model development effort at GFDL, and later directed much of the GFDL research on data assimilation and extending the range of deterministic predictability.

2.2

In the top panel air parcels are shown ascending moist adiabatically in the updrafts of deep convective clouds (BC) and descending much more slowly in clear air (CA), while undergoing radiative cooling. While residing in the boundary layer (AB) they take up sensible heat and water vapor from the ocean surface. Represented as a sequence of reversible processes BC-CA-AB on thermodynamic charts, this cycle assumes the form of a heat engine. These schematics are most directly applicable to the Hadley cell in tropical overturning circulation in general, but they also offer some insight into the overturning circulations in baroclinic waves at extratropical latitudes.

2.6.1a

Charney and Eady modes: alternative representations of the fastest growing linear modes of baroclinic instability.

Provided by Ian James.

2.6.1b

Two species of finite amplitude baroclinic waves that develop from the linear, modal structure shown in the previous figure, pictured as they are nearing their peak amplitudes, referred to as Life Cycles 1 and 2. The colored shading represents surface temperature (darker shades warmer) and the contours represent SLP. The maps are images from the corresponding videos in the Animations Library.

Provided by John Methven.

2.9a: Lithograph of the Krakatos Eruption, 1883.

From Wikipedia.

2.9b

Horace Lamb discovered the wave that bears his name, a hybrid gravity and acoustic wave. G.I.Taylor provided convincing evidence that the most rapidly propagating waves emanating from the Krakatoa were Lamb waves.

3.0a: Victor P. Starr

Student of Rossby's at the University of Chicago. Championed the idea of using global balance requirements to diagnose the processes that maintain the general circulation through his course in the Department of Meteorology at MIT and the training of students.

3.0b: Overview of Part II

3.1a

Basic definitions of angular momentum per unit mass and atmospheric angular momentum (AAM); 20-year-long AAM time series showing seasonal variations and higher frequency fluctuations.

Provided by Ying.

3.1b

60-year long LOD time series with low frequency signature of mantle convection superimposed upon higher frequency variations in AAM.

From Wikipedia.

3.1c

Orographically induced gravity waves arrayed parallel to the ranges of the Appalachian mountain ranges in the eastern US.

3.1d

Magnified segments of Fig. 21.10 in the text showing the strong imprint of orography upon the climatological mean 500 hPa height field in the ERA5 reanalysis.

3.1e

Principals in the Palmen/Starr debate

3.1-1a: North Island

October 6th, 2014

3.1-1b: South Island

October 16th, 2014

4.2a

Pole-to-pole meridional profile of zonally averaged evaporation minus precipitation, as in Fig. 4.8 of the text, shown together with the divergence of the zonally averaged, meridional water vapor transport, as in Fig. 4.10 of the text.

4.2b

Satellite sensed distributions of evaporation and precipitation and an estimate of the divergence of the water vapor transport based on the surface wind field derived from satellite altimetry and the column water vapor.

Provided by Timothy Liu.

4.2c

Global climatology of ocean color based on NASA SeaWIFS data highlighting the five prominent tropical zones of low productivity, indicated by the deep blue patches, the nutrient-rich equatorial and coastal upwelling zones, and the zones beneath the subpolar lows, where ''Ekman pumping'' brings nutrients up to the surface.

Provided by the NASA/GSFC SeaWIFS Project. To view the time-dependent field of ocean color, see Animations 1.4-9 and 1.4-10.

4.2d

Global climatology of gross primary productivity over the continents based on the Normalized Differential Vegetation Index (NDVI). Zoom in on this high resolution image to view regional features.

Provided by NASA. To view the time-dependent, NDVI-based field of gross primary productivity see Animation 4.1-7.

4.2e

World ocean salinity climatology, as in Fig. 4.12 of the text but with higher resolution.

Provided by NASA. See also Animation 4.2-3.

4.2f: The cryosphere: the fractal distribution of Arctic pack ice in summer.

The spaces of open water between the pieces of ice are referred to as leads. Fractional coverage is a macroscale measure of the area covered by video, as opposed to leads. During early winter ice forms over the leads and thickens as the season progresses.

Provided by NASA/SVS. See also Animations 4.2.4a and 4.2.4b.

4.2g: The cryosphere: Antarctic pack ice shown together with the much more massive continental ice sheet.

Provided by NASA/SVS.

5.4a: Top-of-atmosphere net radiation

Top-of-atmosphere net radiation, as in the top panel of Fig. 5.5 in the text, but for DJF and JJA. The large imbalances are related to the storage of heat in the upper layer of the ocean in the summer hemisphere and the extraction of it in the winter hemisphere. Averaged over the year, these large imbalances cancel, leaving the weaker, equatorially symmetric pattern shown in Fig, 5.5.

5.4b: MODIS imagery showing mainly low clouds on a winter day with cold westerly surface winds.

The elongated east-west bands are cloud streets, aligned with the low-level wind shear. They are the upward branches of shallow convective cells, which produce strong upward fluxes of sensible heat where the cold, relatively dry air passes over the relatively warm surfaces of the lakes, The clouds form some distance downstream of the windward shore, and they thicken as they move downstream across the lake. Under some conditions these clouds can produce large snowfalls over the hills just inland of the downstream shores of the lakes. Gravity waves transverse to the flow are discernible over Georgian Bay, to the northeast of Lake Huron.

Image provided by the NASA Earth Observatory.

5.4c: MODIS imagery showing mainly low clouds on a winter day with cold westerly surface winds.

As in the previous image, but over the US eastern seaboard with low level flow from the north northwest. In this case, the clouds are organized in the form of cellular convection, which breaks out ~100 km downstream of the coast except in Chesapeake Bay and near the mouth of the Delaware River. Gravity waves transverse to the flow are discernible upstream, over the Appalachians.

Image provided by the NASA Earth Observatory.

5.4d : MODIS imagery showing mainly low clouds on a winter day with cold westerly surface winds.

As in the previous two images but over the Black Sea. This field of clouds is more richly textured, with cloud streets and gravity waves intersecting one another more or less at right angles.

Image provided by the NASA Earth Observatory.

6.7a

A set of orthogonal functions in a spherical domain that can be used to partition atmospheric fields based on horizontal scale, expressed in terms of two-dimensional wavenumber. In these figures, which are adapted from Wikipedia, m is the zonal wavenumber, the index of a set of trigonometric functions on latitude circles and l is the meridional wavenumber, the index of a set of Legendre polynomials on meridians. (Note that the conventions for the symbols are different in the text.) The two dimensional wavenumber is given by k = m + l. If atmospheric fields are partitioned into long and short wavelengths in terms of zonal wavenumber, the long waves tend to be zonally elongated and the short waves meridionally elongated, but if the partitioning is performed in terms of two-dimensional wavenumber, there is no inherent bias (Blackmon 1976). These patterns can be viewed rotating around latitude circles in Animation 6.7.

7.0a

Arnt Eliassen's paper on the dynamics of the geostrophically balanced zonally symmetric flow (Palmé 1951) laid the groundwork for the formalism described in Chapter 7, and the Eliassen-Palm flux, introduced in Chapter 8, derives from his and his student, Erik Palm's theoretical study of the transport of energy mountain waves.

7.0b

Francis Bretherton and his former students dominated the field of wave-mean flow interaction in the atmosphere and ocean and the dynamics of finite amplitude baroclinic waves from the late 1960s.into the 1990s, a period that saw many important advances in our theoretical understanding.

7.0c

Michael Edgeworth McIntyre (right), a student of Bretherton's and his student, David Andrews (left) played a central role in formulating and articulating the meaning of the transformed Eulerian mean equations for predicting the evolution of a zonally symmetric vortex and the associated mean meridional circulations. Their formalism has been widely used in studies of stratospheric dynamics.

9.0a

G. W. B. Dobson (right) invented the ozone spectrophotometer (1924). He was among the first to recognize the warmth of the stratopause level relative to the layer below and to attribute it to the heating due to the absorption of UV radiation by ozone. Recognized that the variability of UV radiation in association with the sunspot cycle has implied actions for atmospheric phenomena.

Alan Brewer (left) developed instrumentation for monitoring water vapor and ozone concentrations in the upper atmosphere. He recognized that the relative humidity of air throughout most of the stratosphere is remarkably low, and postulated that the air must have been dried while ascending through the tropical cold point tropopause.

9.0b

Taroh Matsuno derived the solutions to the shallow water wave equations for planetary waves on an equatorial beta plane. He was also the first to represent the essential dynamical processes that give rise to stratospheric sudden warmings in a numerical model. The photo at right, provided by the UCLA Department of Atmospheric and Oceanic Sciences, shows the young Matsuno at Tokyo University with colleagues Michio Yanai and Isamu Hirota.

9.0c: Richard J Reed

Co-discoverer of the QBO and the first to document its structure and behavior based on a short record of rawinsonde data at a few equatorial stations. He also contributed to our understanding of convectively coupled waves in the tropics.

9.0d

Richard S Lindzen and James R Holton proposed a mechanism for the QBO based on the interactions between vertically propagating gravity waves and the background zonal flow, which has withstood the test of time. Among Lindzen's other notable contributions are his theoretical analyses of atmospheric tides and vertically propagating planetary waves on beta-planes. Holton played a leading role in explaining how dynamical processes mediate the distributions of ozone, water vapor and other trace substances in the lower stratosphere.

9.2.1a

9.2.1b

9.2.1c

12.1a

Left panel: The NH winter 5-day mean 500 hPa height field (Z500) regressed onto the cosine coefficient of the second harmonic of Z500 on the 50°N latitude circle. By construction, it exhibits a prominent k = 2 pattern centered on 50°N, but it also projects upon the PNA pattern.

In the corresponding pattern for 5 days layer, shown in the right panel, the atmosphere's memory of the wavenumber 2 pattern is fading, while the memory of the PNA pattern persists.

13.1a: Correlation coefficient between Z1000 and Z500 at individual grid points based on 5-day mean data.

The high correlations over the oceans are indicative of perturbations with an equivalent barotropic structure, whereas the low correlations over the major mountain ranges are indicative of a more baroclinic structure with strong associated temperature perturbations.

From Hsu and Wallace (1985).

13.1b

Left panel: one-point correlation map for SLP for a grid point in the Yukon. The pattern is reminiscent of EOT6 of SLP in Fig. 13.26 of the text but shifted eastward by about 20 degrees of longitude.

Right panel: the corresponding Z500 field correlated with the same SLP time series. Note the low correlations in the vicinity of the reference grid point, consistent with the previous figure, and the relationship between the SLP and Z500 patterns. Over the ocean sector they are remarkably similar, indicative of an equivalent barotropic structure, whereas over the Rockies, they are entirely different owing to the highly baroclinic character of the pattern.

13.1c: Imprint of the Northern Hemisphere annular mode (NAM) upon the biosphere.

Correlation maps for the variables indicated by the titles with a reference time series that reflects the drawdown of CO2 each year during the Northern Hemisphere growing season, constructed from CO2 measurements provided by the NOAA/ESRL/GML. Winters with above-normal values of the NAM index tend to be abnormally warm over most of the area of the boreal forests, resulting in a more vigorous growing season, with a higher than normal CO2 drawdown. For further specifics, see (Russell and Wallace 2004). Nearly 20 years have passed since the publication of that paper. It would be interesting to see whether the relationship has held up.

14.0a

Left: Herbert Riehl, a graduate of "the Chicago School", became one of the world's most prominent tropical meteorologists. His interests were global and encompassed the jet stream, which was discovered during his early career, and the Hadley cell. He documented the properties of easterly waves.

He and his student, Joanne Starr Malkus Simpson (right) wrote an influential paper on penetrative convection, which is still widely referenced. Simpson played a leading role in promoting and implementing NASA's Tropical Rainfall Measurement Mission (TRMM), which provided the dataset used in many of the figures in this book. She was the first woman to achieve prominence in general circulation research.

14.0b: Adrian Gill

Adrian Gill, best known in the general circulation community for his theoretical solutions of the planetary weave response to a tropical heat source, shown in Animation 15.3c.

14.0c: Gilbert T Walker

Gilbert T Walker was a British Mathematician who spent much of his career in India, working on monsoon prediction. Based on a multivariate analysis, which bears some resemblance to EOF analysis, he discovered the atmosphere's most prominent pattern of interannual variability, which he referred to as the Southern Oscillation. He also discovered the North Atlantic Oscillation (NAO) and an analogous pattern in the Pacific sector that he referred to as the North Pacific Oscillation (NPO).

14.0d

Jacob Bjerknes's analysis of extratropical cyclones and their associated fronts, performed early in his career, has proven to be one of the foundations of synoptic meteorology. Decades later he turned his attention to atmosphere-ocean interactions, first in the extratropics and later in the tropics. He was the first to recognize and clearly articulate the strong relationship between Walker's Southern Oscillation, which encompasses the entire Pacific basin, and the episodic warmings along the coast of South America, referred to as El Nino, and to deduce the nature of the positive feedback that is responsible for the strong coupling between the atmosphere-and ocean.

14.0e

Left: Eugene M. Rasmusson, best known for his compositing analysis of El Niño events, which revealed many of their salient features. He was instrumental in the development of gridded analyses of SST dating back to the late 19th century.

Right: Klaus Wyrtki, a physical oceanographer, whose analysis of sea level records elucidated the role of the ocean in El Nino.

14.0f

Paul R. Julian (left) and Roland A. Madden, credited with the discovery of the Madden Julian oscillation. Pictured with other members of their research group at NCAR, (left to right) are Dennis Shea, Chester Newton and Harry van Loon. Madden was also the first to identify the external modes discussed in Section 21.3 of the text in analyses of station data.

This photo, provided by Dennis Shea, was taken in the early 1970s.

14.3a

The five subtropical subsidence zones in annual mean fields. Colored shading indicates the 850 hPa vertical velocity; arrows indicate 1000 hPa winds, and the contours indicate 1000 hPa height. Excerpted from Fig. 14.6 of the text.

14.3b: Manifestations of the SSZs in various annual mean fields.

(Top left) lower tropospheric diabatic heating (mainly radiative cooling) rate, as in Fig. 1.16 of the text.

(Top right) SST — the departure from the zonal mean on each latitude circle, as in Fig. 1.8; (middle left) 850 hPa vertical velocity and 1000 geopotential height and wind, as in Fig. 14.6; (middle right) low cloud fraction, as in Fig. 14.1; (bottom left) 850 hPa wind and horizontal temperature advection, as in Fig. 14.7; and (bottom right) 1000 hPa wind and divergence, as in Fig. 14.8.

14.3c

Sea surface temperature (colored shading), surface winds (arrows), and clouds (gray shading). The undulations in the equatorial front are tropical instability waves. Based on NASA QUIKSCAT, TMI, and MODIS imagery.

Provided by Robert Wood.

14.3d

Annual mean near-surface currents, showing the South Equatorial Current (SEC) and the North Equatorial Countercurrent (NECC). Adapted from Fig. S.14.10 of the Solutions Manual.

14.3e

(Top) Annual mean near-surface streamlines and current speed (shaded) from drifter data. (Bottom) Annual mean 1000 hPa winds and divergence fields. Orange (blue) denotes divergence (convergence). The middle panel shows the top and bottom panels superimposed.

Top panel provided by Gregory Johnson, NOAA/PMEL. The bottom panel is repeated from Fig. 14.8 in the text.

14.3f

Annual mean fields derived from simulations with a fully coupled atmosphere-ocean model run with present day forcing and continental geometry for a forward and backward-rotating Earth, as indicated. (Left panels) SST; (right panels) precipitation and surface wind. From the experiment described in (Mikolajewicz et al. 2018) and discussed in the solution of Exercise 11.11.

Provided by Uwe Mikolajewicz.

16.1a

(Top panels) 150 and 850 hPa streamfunctions regressed on monthly mean rain rate averaged over grid boxes 40 degrees of longitude in width and extending from 5° to 15°N: a composite of patterns computed at 10 degrees of longitude intervals around the latitude circle, with each one shifted in longitude so that it is centered on the Date Line. Based on data for JJA only. The corresponding nondivergent wind directions are indicated by arrowheads.

(Bottom panels) the boxes over which rain rate is averaged extend from 5° to 15°S and are based on DJF data only.

Provided by Angel Adames.

16.1b

Shows compensation between the eddy forcing G and the Coriolis force associated with the Hadley cell, which straddles the equator at the times of the solstices.

17.1a: Chronology of El Nino events based on SST indices

Provided by Xianyao Chen.

17.1b

Comparison between EOF1 of global, monthly mean SST - the departure from the global mean at each grid point -- and the regression pattern based on the cold tongue index (CTI) cold tongue index.

Provided by Xianyao Chen.

17.1c: Nonlinearity of the ENSO rain rate signature

(Left) Patterns of rain rate anomalies associated with El Niño vs. La Nina.

(Right) The same patterns superimposed upon the pattern of annual climatological mean rain rate. During El Niño, heavy rainfall intrudes into the western end of the dry zone, whereas during La Nina, the dry zone intrudes into the belt of heavy rain rate just to the west of it. Rain rate anomaly patterns from Hoerling et al. (1997).

17.1d

(Top and middle) monthly fields of SST and column water vapor W regressed upon Niño 3.4. (Bottom ) climatological annual mean column water vapor Wc. In accordance with the Clausius Clapeyron equation, the saturation vapor pressure at the ocean surface at each grid point increases at a rate of ~7% /°C. If we assume that the logarithmic rates of change of saturation vapor pressure at sea level and column water vapor are roughly comparable, the ENSO-related δW/W should be roughly proportional to the product of the ENSO-related δSST (top panel) and Wc (bottom panel).

In the field of the product Wc x δSST, the maximum is shifted westward and the band of high values along the equator is widened meridionally relative to the SST signature, in agreement with the observed pattern shown in the middle panel. See also Fig. 17.12 of the text and 17.12 in the Exercises for the use of instructors.

17.1e: Time-longitude sections: averages from 2°N to 2°S.

80°W corresponds to the coast of South America. Tick marks refer to the beginning of months. (Left) zonal wind based on scatterometer data, and (right) sea level based on satellite altimetry. The sea level data exhibits the distinctive signature of equatorially trapped Kelvin waves forced by zonal wind anomalies in the central and western Pacific, which propagate eastward with a phase speed of about 3 m/s. Downwelling waves give rise to positive height anomalies and vice versa. The zonal wind pattern is more chaotic and more subject to sampling variability,

During this particular interval westward propagating Rossby waves dominate, but there are intervals when westward propagating Kevin waves are more prominent, A notable feature in this section is the two-week-long period of westerly anomalies in the eastern part of the basin during March 2023, which forced a downwelling Kelvin wave with elevated sera levels along the South American coast. Tropical instability waves are evident in both panels.

Provided by Qihua Peng.

17.1f: Survey of global impacts of ENSO.

Anomalies typically observed during El Niño events.

Provided by NOAA.

17.1g

(Top) 12-month running mean time rate of change of CO2 concentration Mauna Loa. Applying the averaging operator removes the strong seasonality associated with the summer drawdown due to photosynthesis in the boreal forests.

(Bottom) Niño 3.4 smoothed with a 5 month running mean filter. Evidently, CO2 is being injected into the atmosphere at a faster rate during El Niño than during La Niña. The excess is attributable to the increased incidence of tropical forest fires, in response to the deficit in rainfall in the tropical continents during El Niño The fluctuations in the apparent CO2 source lag those in Niño 3.4 by about 3 months. See also (Keeling et al. 2017).

20.2a

Photograph taken nside the eye of Hurricane Katrina over the Gulf of Mexico August 29 2005, when it was a Category 5 storm. The outward slope of the eyewall cloud with increasing height is clearly discernible.

Provided by NOAA hurricane reconnaissance aircraft.

21.5a

Mechanical energy spectra in ERA-I and ERA5 plotted on a log–log scale, partitioned into Rossby waves and inertio-gravity waves by projecting data onto the theoretically-derived normal modes. The analogous spectrum for ERA-I only appears as Fig. 21.11 of the text. Note that the crossover point, beyond which IG waves have more mechanical energy than Rossby waves occurs at a lower wavenumber in ERA5 than in ERA-I.

The ERA5 spectrum is from Stephan and Mariaccia (2021).