# Presentation: 788887

## The new hurricane-land coupled system and its test for landfalling tropical cyclones 

- Weixing  Shen
- In collaboration with
- R. Tuleya, K. Mitchell, N. Surgi, and S. Lord

**Notes:**
 1. The LSM used in the new system is the Noah;   
 2. The new system was tested for the previous season for landfalling....  In terms of verification and better understanding..

## Objectives

**Extending and improving the capabilities of the current operational hurricane model during hurricane landfall by replacing the present slab land surface model with the comprehensive Noah land surface model.**
**2. Investigating the significance of land surface interface exchanges on hurricanes during landfall.**
**3.  Verification.**

**Notes:**
       1. What kind info and the sources.             
       2. Coupling with a comprehensive LSM enables us do more. * The diff that not only the physics diff. The data the & the data also count
       3. The significance and the verification are still ongoing studies 

**The quasi-operational hurricane-land coupled system**

**Global fixed data**

- GFS analysis

- Eta analysis
- (Edas/Noah)

- Initial land
- conditions

- Initial atmospheric
- conditions

- GFDL hurricane
- model

- Radiation fluxes
- Precipitation
- Vs,Tair,Ps & rh

- Skin temperature
- Sensible heat
- Evaporation

- Noah LSM

- Soil moisture
- Runoffs

**Notes:**
   1. In this diagram, I highlighted the places where the coupling project touches  2. The land and hurri are connected by an interface similar...
   3. Much of the engineering work was actually dealing with the exchanges in the situation of movable meshes and multi-processors.

## 75x75   r=1/2

-  11 x11
-   r =1/6

-  o

-  o

-  o

-  o

-   o

**Notes:**
 1. Now, here gives the  domain info with a vegetation background
 2. For the land outside of the Edas domian but in the hurri one,...
  To give you a sense what is like the land surface condition changes with the lsm change, here is an example of soil moisture

## Soil moisture

**Fixed wetness in the slab**

**Soil**** ****moisture**

- Lili (2002,10/02 12Z)

**0h**

**42h**

**9-day**

- Kyle (10/11 12Z)

**(**

**(**

**(**

**)**

**)**

**)**

## Roughness

**Roughness**

-      6

**Notes:**
Here is the roughness Noah vs the slab. The upper one is the znot corresponding to vegetable types used in the new system. 
So let me start with the test for the previous season cases 

## The year of 2003

-                                     Landfall time          Landfall by model
**Bill:**
-       06/30, 00Z               06/30, 17Z               06/30, 23Z
-       06/30, 12Z
**Claudette:**
-       07/14, 12Z               07/15, 19Z               07/15,18Z
-       07/15, 12Z
**Isabel:**
-       09/17, 12Z               09/18,  18Z              09/19,00Z
-       09/18, 06Z
-       09/18, 12Z

- 7

**Notes:**

Let me start with the Claudette case.

## Track prediction

**Track prediction**

**Notes:**
   The diff between the operational run by green and the slab run by red is ..... 
   2. The black dots are for the observed positions every 6h. I could get more but by the time we run.....

## Intensity

**Intensity**

**Notes:**
    1. The upper is for ................
    2. Little but not much. This is true for majority of the cases but occasionally.....
   Now, let’s look at the precipitation

## 10

**Notes:**
 1.  First, I would like to point out that the gfdl hurri model somehow produces sporadic .... in the environment
 2.  Now, if we look at the rainfall along the storm track........
  So, we further examined the difference by calculating storm-induced maxi and total  precip for every six hours.... 

## (   

- )

- 6h

-  r=300 km

**Area of precipitation accumulation**

## 12

**Notes:**

Now, let’s see another case

## 13

**Notes:**
 This is a day accumulation for Isabel. On the left side.........

## Rainfall Verification 

- LSM better

- LSM better
-          worse

- 14

**Notes:**

Now, let me show the very different case.

## 15

**Notes:**

 Since we don’t have many landfall cases for the last season,...

## Slide 16

**Notes:**

For consistence,  the version of the 2003 hurricane model is used. The land...... 

## Slide 17

##  ***: No data

-  ***: No data
-  Red: Better
- Blue: worse

## Slide 19

**Notes:**
For the Vs, occasionally, there are some difference mainly due to the roughness diff, while the roughness impact on Ps is more insignificant 

## Precipitation change (percentage) relative to the slab

- Areal total

-  Red: Increase
- Blue: Decrease

**Notes:**
       1.Here the value shows the percentage change relative to the rainfall by using the slab LSM. 
            red means increase, blue means reduction.
       2. There are large variabilities  from time to time and case to case but ovearll the    

##                      Change of maximum local precipitation 

-                      **Change of maximum local precipitation **

## 6h accumulation

- mm

**Edouard (2002, 9/15 12Z********18Z)**

## http://www.nhc.noaa.gov/tracks/2002atl.gif

## Future Work  

**Verification of precipitation**
**Detailed case analysis**
**Hurricane-land-ocean coupled system**
**Other issues during landfall**

## Main conclusion

**The difference with the Noah LSM is generally small **
**in tropical cyclone track and intensity although the  **
**impact can occasionally be significant. However, the precipitation difference is much more pronounced, implying the relative importance of land surface coupling in predicting inland rainfall and flooding.**