# Presentation: 363838

## Unraveling the Stable Boundary Layer Puzzle Using Doppler Lidar and Other Data from CASES-99

**Unraveling the Stable Boundary Layer Puzzle Using Doppler Lidar and Other Data from CASES-99**
**Robert M. Banta**
*Environmental Technology Lab/NOAA, Boulder, Colorado*
*	*

## New Applications for Models 

-   **Air quality**
-   **Emergency response/’homeland ****	****security’**
-   **Fire wx;  wind energy**
**The new applications require different conditions to be well predicted, e.g. light-wind periods for air quality.**
- 	> a lot is being asked of NWP models

## Stable Boundary Layer

**Stable Boundary Layer**
*Occupies ~**1⁄2 of diurnal cycle*
*Affects:*
-    **accuracy of the model run itself**
-     **predicted transport by nocturnal flow ****	****(AQ,ER)**
-     **point fcsting – downscaling for local fcsts**

## Slide 4

## Stable Boundary Layer

**Stable Boundary Layer**
*Occupies ~**1⁄2 of diurnal cycle*
*Affects:*
-    **accuracy of the model run itself**
-     **predicted transport by nocturnal flow **
**	****(AQ, ER)**
-     **point fcsting – downscaling for local fcsts**

## Types of Boundary Layer 

-   **Unstable, convective BL  =  CBL**
** ****mixed, sfc meas representative of ****	****aloft, can model**
-   **Moderately stable BL  =  mSBL**
** ****stronger winds, ~continuous turbc**
** ****relationships between fluxes and ****	****gradients well behaved**
** ****can model ok**
**  ****Very stable BL  =  vSBL****	*****(-Mahrt)***

## Very stable BL (why ugly)

-  Light wind, strong stability *(v. cold sfc)*
-  Turbulence - patchy, sporadic, 	intermittent...  and thus nonstationary
-  Traditional anls techniques don’t apply
-  Relationships between fluxes and profiles:     	v. complex
-  Lack of mixing → lots of small-scale stuff
-  Control by ‘features’; turbc can be imported
-  Hard to model, or represent in models

## Issues 

-   **Surface – important source / sink**
** ****source: water vapor, heat (day)**
** ****removal: moment., heat (night), chem spp. (O****3****, e.g.)**
**  ****Need to get sfc-atmos ‘communication’ right**
-   **Stability suppresses mixing, turbc *****(unlike day)***
-   **Magnitude of mixing  ****←  shear**
**  ****Sources of shear**
** ****mixing to sfc; but suppressed in strong stability**
** ****LLJ**
**  ****LLJ  ****→  shear  →  turbc  →  mixing**

## Slide 9

## Topographic Contour map, CASES site, 

**Topographic Contour map, CASES site, **
**southeastern Kansas**

## Slide 11

## Slide 12

## Slide 13

## Key LLJ Measurements - 

-   **peak speed**
-   **height**
**	**
-   **direction, any directional shear**
-   **structure of waves / turbc below max**
-  - ***is effective mixing taking place? ***
**         *****(DD? cf. chem)***
-   	 - ***over how deep a layer?*****	**
**  ****stability **

**Key LLJ Measurements -**** **
**      *****characteristics of jet max***

- Zmax

- Umax

- U

- Z

- }

- ∆U/∆Z

## Slide 15

## 200 m

- 0

- 1

- 2

- 0

## Slide 17

## Slide 18

## Slide 19

## Slide 20

## Slide 21

## Slide 22

## Richardson Numbers

- Gradient Ri
- 		Ri = (g/θ)(dθ/dz) / (du/dz)2
- ‘Jet’ or Bulk RiJ
- 		RiJ = (g/θ)(dθ/dz) / (UX/ZX)2

## Slide 24

## Slide 25

## Slide 26

## Slide 27

## Slide 28

## Slide 29

## Good news  ↔  Bad news

**   ****Good News****:  turbc, mixing related to gross ****	****LLJ properties; bulk shear, stability**
**     ****Bad News****:  vSBL – still get some mixing, but ****	****don’t know impact or how to handle**
**     ****Possibilities – I :**
**	****-****  mixing small, doesn’t matter (any way of ****	****	****	****handling OK)**
**	****-****  mixing small, matters (need to get ****	****	****	****magnitude, location right or simulation compromised)**
**Kicker****:  numerical stability = requires exceedance ****	****of min value!**

##  - wave packets (shear instability):  IOP2 CASES

** ****-**** ****wave packets (shear instability):  IOP2 CASES**
**   ****  ****density currents: mini fronts, solitons**
**     ****drainage-flow effects:  **
**	****at night, all topography is complex (****↔ day)**
**     ****Arctic - ****compressed Ekman layer,**** **
**	****K****H ****/ K****M**** = f (stability)      (A.Grachev)**
**     ****transient “misc. mesoscale disturb.” (L.Mahrt)**
**Possibilities II :**
**     ****tractable**
**     ****intractable, and unimportant**
**     ****intractable, but important !**

## Slide 32

##    wave packets (shear instability):  IOP2 CASES

**   ****wave packets (shear instability):  IOP2 CASES**
**   **-** ****density currents: mini fronts, solitons**
**     ****drainage-flow effects:  **
**	****at night, all topography is complex (****↔ day)**
**     ****Arctic – compressed Ekman layer, **
**	****K****H**** / K****M**** = f (stability)      (A.Grachev)**
**     ****transient “misc. mesoscale disturb.” (L.Mahrt)**
**Possibilities II :**
**     ****tractable**
**     ****intractable, and unimportant**
**     ****intractable, but important !**

## Slide 34

## Slide 35

## Slide 36

##    wave packets (shear instability):  IOP2 CASES

**   ****wave packets (shear instability):  IOP2 CASES**
**   **** **** ****density currents: mini fronts, solitons**
**     ****drainage-flow effects:  **
**	****at night, all topography is complex (****↔ day)**
**  ** **-** **Arctic – compressed Ekman layer, **
**	****K****H**** / K****M**** = f (stability)      (A.Grachev)**
**     ****transient “misc. mesoscale disturb.” (L.Mahrt)**
**Possibilities II :**
**     ****tractable**
**     ****intractable, and unimportant**
**     ****intractable, but important !**

## Arctic:  Evolving Ekman-type spirals during the polar day observed during JD 142 (22 May, 1998) for five hours from 12.00 to 16.00 UTC (4:00–8:00 a.m. local time, see the legend). Markers indicate ends of wind vectors at levels 1 to 5 (1.9, 2.7 4.7, 8.6, and 17.7 m). (A. Grachev et al. BLM, 2004). 

## Arctic: Schematic diagram of the SBL scaling regimes as functions of the stability and height. Here   2 m (level 1). Dividing lines between the scaling regions are sketched (A. Grachev et al. BLM, 2004). 

##    wave packets (shear instability):  IOP2 CASES

**   ****wave packets (shear instability):  IOP2 CASES**
**     ****density currents: mini fronts, solitons**
**     ****drainage-flow effects:  **
**	****at night, all topography is complex (****↔ day)**
**     ****Arctic - ****compressed Ekman layer,**** **
**	****K****H**** / K****M**** = f (stability)      (A.Grachev)**
**     ****transient “misc. mesoscale disturb.” (L.Mahrt)**
**Possibilities II :**
**     ****tractable – accurate estimates of sfc fluxes psbl**
**     ****intractable, and unimportant**
**     ****intractable, but important !**
- Last case – still ***critical*** to assess / bracket
- uncertainty in predictions

## What to do...?  Why am I here ?

**   ****Continue with analysis of CASES-99 data; test generality of LLJ findings**
**     ****assess model capabilities to reproduce observed features (e.g., LLJ), profiles, and to represent mixing-related processes**

## Some Plans:  More specifically

**Some Plans:  More specifically**
-      **test with** ***CASES, Nashville, Lamar CO *****datasets**
***   ******  *****Model comparison: hgt / spd / dir of LLJ**
***  ******Values of TKE in subjet layer (Bao)***
***  ******Usefulness of 2-eq’n (TKE- ******l******) turbc model (Bao)***
* *
-      **CASES analysis**
*** ******mSBL: what is it like?  upside down?  (L.Mahrt)***
*** ******slightly more stable:  still get upside down ?( “ )***
***  ******how does sfc-atmos communication work? ( “ )***
***  ******which ‘features’ have  large/small roles in vert transport, profile control?***
-      **Larger scale:  ****V****geo****, ****V****ageo****, rad cooling (J. Sun)****	****- influence on LLJ structure. properties**

## TKE Equation

**TKE Equation**

**Two-Equation Model**

**One-Equation Model**

**one-equation model: ********v**

**two-equation model: ********v**

**one-equation model: 2 x ******

**two-equation model: 2 x ******

## Some Plans:  More specifically

**Some Plans:  More specifically**
-      **test with** ***CASES, Nashville, Lamar CO *****datasets**
***   ******  *****Model comparison: hgt / spd / dir of LLJ**
***  ******Values of TKE in subjet layer***
***  ******Usefulness of 2-eq’n (TKE- ******l******) turbc model (Bao)***
* *
-      **CASES analysis**
*** ******mSBL: what is it like?  upside down?  (L.Mahrt)***
*** ******slightly more stable:  still get upside down ?( “ )***
***  ******how does sfc-atmos communication work? ( “ )***
***  ******which ‘features’ have  large/small roles in vert transport, profile control?***
-      **Larger scale****:  ****V****geo****, ****V****ageo****, rad cooling (J. Sun)****	****- influence on LLJ structure. properties**

## Conclusions

** ****Define problem as I see it; offer ****	****suggestions...**
** ****Connection established – LLJ and lower ****	****atmos. turbc**
** ****vSBL: marked by proliferation of small-****	****scale features of unknown importance ****	****and impact = messy, not understood**
** ****Collaboration: understand and assess **
** ****Possibility: major contributor may be ****	****complex terrain effects**

## Some References

**Banta, R.M., R.K. Newsom, J.K. Lundquist, Y.L. Pichugina, R.L. Coulter, and L. Mahrt,   2002:  Nocturnal low-level jet characteristics over Kansas during CASES-99.  *****Boundary-Layer Meteor.*****, 105, 221-252.**
**Banta, R.M., Y.L. Pichugina, and R.K. Newsom, 2003:  Relationship between low-level jet properties and turbulence kinetic energy in the nocturnal stable boundary layer.  *****J. Atmos. Sci.*****, 60, 2549-2555.**
**Newsom, R.K., and R.M. Banta, 2003: Shear-flow instability in the stable nocturnal boundary layer as observed by Doppler lidar during CASES-99.  *****J. Atmos. Sci.*****, 30, 16-33.**
**Sun, J., D. Lenschow, S. Burns, R. Banta, R. Newsom, R. Coulter, S. Frasier, T. Ince, C. Nappo, B. Balsley, M. Jensen, L. Mahrt, D. Miller, and B. Skelly, 2003:  Intermittent turbulence in stable boundary layers and the processes that generate it.  *****Boundary-Layer Meteor.*****, 106, in press.**
**Sun, J., Sean P. Burns, Donald H. Lenschow, R. Banta, R. Newsom, R. Coulter, S. Frasier, T. Ince, C. Nappo,  J. Cuxart, W. Blumen, X. Lee, and X.-Z. Hu, 2002:  Intermittent turbulence associated with a density current passage in the stable boundary layer.  *****Boundary-Layer Meteor.*****, 105, 199-219.**
**Poulos, G., W. Blumen, D.C. Fritts, J.K. Lundquist, J. Sun, S.P. Burns, C. Nappo, R, Banta, R. Newsom, J. Cuxart, E. Terradellas, B. Balsley, and M. Jensen, 2002:  CASES-99: A comprehensive investigation of the stable nocturnal boundary layer.  *****Bull. Amer. Meteor. Soc.*****, 83, 555-581.**
**Darby, L.S., R. M. Banta, W.A. Brewer, W.D. Neff, R.D. Marchbanks, B.J. McCarty, C. J. Senff, A.B. White, W.M. Angevine, E.J. Williams, 2002:  Vertical variations in O3 concentrations before and after a gust front passage.  *****J. Geophys. Res.*****, 107, D13, 10.1029/2001JD000996.**
**Grund, C.J., R.M. Banta, J.L. George, J.N. Howell, M.J. Post, R.A. Richter, and A.M. Weickmann, 2001: High-resolution Doppler lidar for boundary-layer and cloud research.  *****J. Atmos. Ocean. Technol.*****, 18, 376-393.**

## Research Activities Concerning

**Planetary Boundary Layer Processes**

-   Evaluation of parameterizations of vertical           	turbulent mixing within and above PBL 	(i.e., TKE and turbulent diffusivities)
-   Diagnosis of PBL height
-   Validation of the energy balance in the   	*coupled* ABL and land- surface processes.
-   Assimilation of PBL observations into 3-D 	models for air-quality related research 	and predictive applications

**one-equation model: ********MC**

**one-equation model: *****l***

**one-equation model: ********H**

**one-equation model: ********M**

**two-equation model: ********M**

**two-equation model: ********H**

**two-equation model: *****l***