# Presentation: 502351

## Upper Air Data

## Layers of the Atmosphere

- AIR TEMP NORMALLY  DECREASES FROM THE EARTH’S SURFACE UP TO AN ALTITUDE OF ABOUT 11 km (7 mi.)
- THE RATE IN WHICH AIR TEMPERATURE DECREASES WITH HEIGHT IS CALLED THE TEMPERATURE **LAPSE RATE.**

***Layers of the Atmosphere***

## Weather Balloons

** ****An instrument called a radiosonde is carried aloft by a hydrogen or helium filled balloon. Height, temperature, pressure, winds, and humidity of the balloon is continuously monitored. The data is transmitted back to computers on the ground. **
**When the balloon bursts, the instrument floats earthward via a parachute****. **

***Weather Balloons***

## Rocketsondes

**Taken by the National Aeronautical and Space Administration and the Department of Defense at various locations to get readings where balloons can not reach, between 100,000 and 200,000 feet. **
**These rocketsondes are carried aloft by rockets and then dropped to measure the meteorological variables.**
**Coding is different than that for balloon data and is not covered in this brief.**

## Mandatory Levels

- There are twelve levels at which data ***must*** be reported in each report, provided the radiosonde and balloon make it that far!
- They are:
- 	**pressure****	****approximate**
**	****level(mb)****	****height(m, MSL)**
- 	surface	     0 (AGL)
- 	1000		   100
- 	925		   800
- 	850		  1500
- 	700		  3000
- 	500		  5500
- 	400		  7500
- 	300		  9000
- 	250		10,500
- 	200		12,000
- 	150		14,000
- 	100		16,000
- 	trop		(variable)

## Mandatory Levels

**TTAA** YYGGiD IIiii 99PoPoPo TTTDD dddff 00hhh TTTDD dddff 92hhh TTTDD dddff PmPmhhh TTTDD dddff ... 10hhh TTTDD dddff  88PTPTPT TTTDD dddff 77PvPvPv 4vbvbvava 51515
**YY**: YY - 50 = day of month; >50 indicates winds in knots.
**GG**: 00 or 12Z
**IIiii**: Station Identifier
**99P****o****P****o****P****o** : Surface Pressure
**TTTDD**: Surface Temp and Dewpoint Depression
**dddff**: 10 meter winds (degrees and knots)
**00hhh**: 1000 mb height
**TTTDD**: 1000 mb Temp and Dewpont Depression
**P****m****P****m**: Next sequential mandatory level

## Significant Levels

***Significant Levels***

- Temperature and/or moisture profile indicating a substantial variation from the U. S. Standard Atmosphere (e.g. tropospheric lapse rate of 6.5 C/km).
- Lapse rate of temperature or dew point is changing significantly.
- Surface and the tropopause.
- All groups are coded similarly to the Mandatory Level group.

## Significant Levels

**TTBB** YYGG0 IIiii 00PPP TTTDD 11PPP TTTDD 22PPP TTTDD ... 99PPP TTTDD 11PPP TTTDD 22PPP TTTDD ... until done, then 31313 0hhmm 8hhmm
**00PPP**: Station Pressure.
**11PPP**: 1st Significant Level
**22PPP**: 2nd Significant Level.
**11PPP**: 10th Significant Level.
**31313**: Indicates supplemental data included.
**0hhmm**: Scheduled time of balloon release.
**8hhmm**: Actual time of balloon release.

## Upper Winds

*Upper Winds*

- All reports are either *fixed regional levels* or *significant wind levels*, and the units are in feet above ground.

## Upper Winds

**PPBB** YYGGa4 IIiii 9tuuu dddff dddff dddff 9tuuu dddff dddff dddff 9tuuu dddff dddff
- Reports winds up to 100 mb.
**9tuuu**:
- t: Tens digit of following number groups (i.e. if t=1, then multiply heights by _1_000).
- uuu: Represents the height of the following number groups (i.e. if uuu=012, then the following groups represent the winds for _0_, _1_000 and _2_000 feet.
**dddff:** Wind direction and speed.
- If ddd ends in 1 or 6 then add 100 to ff.

## The IIiii Structure

**II:** block number is allocated to the services within each Region by regional agreement.
- Region III: South America ........................ 80-88
- Region IV: North and Central America .........70-79
**iii:** Station numbers, corresponding to a common block number (II) except 89 are usually distributed so that the zone covered by a block number is divided into horizontal strips; e.g. one of several degrees of latitude. Where possible, station numbers within each strip increase from west to east and the first figure of the 3-figure station number increases from north to south.

## Data Uses

**Data Uses**

**Primary input into the large scale atmospheric models from which most forecasts are based. **
**Aid in the forecasting of thunderstorms, cloud cover, temperature, and other elements. **
**Input for Skew-T Diagrams**

## IREPS

**HEIGHT  IN  FEET**

**RANGE  IN  NAUTICAL  MILES**

**E2  AIRCRAFT  POSITIONED  AT  17K  FT**

## WIND  EFFECT  ON  TLAM

**WIND**

**TLAM  ****COURSE**

**TLAM****HEADING**

## GUIDANCE SYSTEM

## GUIDANCE SYSTEM

- _GUIDANCE SYSTEM_

## Where to Find Soundings

- Florida State University
- www.met.fsu.edu/weather/
- 199th Weather Flight
- www.dod.hawaii.gov/199wf/index.html#weather
- Research Applications Program
- www.rap.ucar.edu/weather.html
- Graphical Interface
- CMW
- NODDS