Transitional Stratocumulus Events

Table 4 lists case dates for transitional events.

Table 4 Case dates selected for LASSO-ENA for its transitional stratocumulus events.

Case

Date

Description

1

2016-05-08

  • Multi-day transitional event with precipitating closed and open cell behaviors

  • Modest winds from the north throughout the event

  • 5-day air mass back-trajectories originating from Greenland

2

2016-05-09

  • Multi-day transitional event with precipitating closed and open cell behaviors

  • Modest winds from the north throughout the event

  • 5-day air mass back-trajectories originating from Greenland

3

2016-10-22

  • Widespread open cell cumulus with small gaps between individual cells

  • Modest winds from the northerly direction throughout the event

  • 5-day air mass back-trajectories originating from Alaska

4

2016-10-31

  • Widespread closed stratocumulus with pockets of open cells to northeast of the domain

  • Modest low-level northerly winds

  • 5-day air mass back-trajectories originating from Quebec, Greenland

5

2017-03-17

  • Multi-day transition to widespread closed cell precipitating clouds over ENA main site

  • Persistent high clouds that built throughout the event

  • 5-day air mass back-trajectories originating from Quebec

6

2017-03-18

  • Multi-day transition to widespread closed cell precipitating clouds over ENA main site

  • Persistent high clouds that built throughout the event

  • 5-day air mass back-trajectories originating from Quebec

7

2017-08-26

  • Daytime development of closed cell conditions over the ENA main site.

  • Light winds from a northerly direction

  • 5-day air mass back-trajectories originating from Nova Scotia

8

2017-11-01

  • Post-frontal open cell cumulus event that transitioned to closed cell behaviors

  • Light northerly winds throughout the event

  • 5-day air mass back-trajectories originating from the North Atlantic, Greenland

9

2018-02-07

  • Stratocumulus with relatively solid deck over the ENA site

  • Light winds from the northeast

  • ACE-ENA campaign day with G-1 aircraft operations

  • 5-day air mass back-trajectories that originated over US central plains

10

2018-05-02

  • Closed stratocumulus deck confined to a narrow band over the Azores

  • Deck gradually thinned, while low-level winds shift easterly

  • 5-day air mass back-trajectories originating from the northwestern US and Canada

11

2018-05-12

  • Extended closed stratocumulus event over the ENA site

  • Regional cloud coverage was less contiguous, but common throughout the domain

  • 5-day air mass back-trajectories originating from western Canada

12

2018-06-27

  • A complex multi-layer cloud event that transitioned into a single layer deck

  • Light westerly winds becoming northerly as the event evolved

  • 5-day air mass back-trajectories originating over the western Atlantic

13

2018-06-30

  • Transitional, multi-day event from closed to open cell cumulus conditions

  • Light northeasterly winds observed throughout the event

  • 5-day air mass back-trajectories originating from the upper Hudson Bay

14

2018-07-01

  • Continuous ENA stratocumulus coverage with broken regional cloud coverage

  • Light low-level winds from the north

  • 5-day air mass back-trajectories that originated from Nova Scotia, Quebec

15

2018-07-30

  • Multi-day closed cell stratocumulus event over the ENA site

  • Broken regional cloud coverage with thin stratocumulus cloud decks

  • 5-day air mass back-trajectories originating over the western Atlantic

16

2018-08-06

  • Multi-day closed stratocumulus event with asymmetric cloud coverage

  • Light low-level winds from the east that shifted westerly

  • 5-day air mass back-trajectories originating from the western Atlantic

17

2018-08-07

  • Multi-day closed stratocumulus event with asymmetric cloud coverage

  • Light low-level winds from the east that shifted westerly

  • 5-day air mass back-trajectories originating from the western Atlantic

18

2019-03-28

  • Closed cell stratocumulus deck with a mixture of precipitating conditions

  • Closed cell conditions formed over a relative narrow (200 km) band

  • 5-day air mass back-trajectories originating from Iceland, the UK

19

2019-03-31

  • Transitional closed to open cell cumulus event

  • Light northerly winds

  • 5-day air mass back-trajectories originating over the northern Atlantic

20

2019-04-04

  • Open cell event with minimal gaps between individual cells

  • Light northerly winds throughout the event

  • 5-day air mass back-trajectories originating from Alaska

21

2019-09-07

  • Continuous stratocumulus deck that gradually thinned, broke

  • Winds from the east

  • 5-day air mass back-trajectories originating from Nova Scotia